The genus can be delineated by the very small to minute proboscis, the costal vein terminating at the point where R₁ joins the wing margin, the small body size of the majority of species, and the restricted distribution in the Namib Desert.

Known only from five disjunct localities in the northern and central Namib Desert in Namibia (Figs 56–57) to which the genus is endemic. A rarely collected genus known only from 18 specimens in museum collections from nine collecting events between 1951–2018 (Table 1). The genus is not known to occur in any currently recognized biodiversity hotspot. Adult flies are either active in early summer or mid-autumn to early winter (Table 2). Nothing is known of the biology.

The species is distinguished from congeners by the overall brown colouration, the greatly expanded metathoracic femora, the apubescent abdominal tergites 3–8 in females, and the restricted distribution in the northern Namib Desert.

Female. Head: black, facial gibbosity brown, in general grey to light brown pubescent, white setose, regular, cylindrical setae; width distinctly greater than thorax (at postpronotal lobe), interocular distance on vertex same as at ventral eye margin; vertex between compound eyes ± horizontally straight, medially only slightly below dorsal eye margin, vertex light brown pubescent, white setose; ocellar triangle apubescent; facial gibbosity distinct, well-developed and discernible in lateral view, mystax covering entire facial gibbosity, white; parafacial area approximately as wide as ¾ width of central gibbosity (at same level); frons not elevated, light brown pubescent, white setose; occiput grey pubescent, yellowish to light brown setose, median occipital sclerite yellowish macrosetose; pocl macrosetae absent; postgena sparsely grey pubescent, long, sparsely white setose; clypeus comprised of single sclerite, entirely sclerotized medially, flat to protruding (convex) ventrally, ventrally expanded, anterior to proboscis (almost covering it), laterally connected to face by sclerotized cuticle; proboscis very short, vestigial, knob-like, brown; labellum indiscernible, length indiscernible, sclerotization indiscernible; maxillary palpus cylindrical, brown, longer than proboscis.

Antenna : brown; scape white setose dorsally, asetose ventrally; pedicel white setose dorsally and ventrally; postpedicel indiscernible (broken).

Thorax : dark brown, predominantly light brown pubescent; scutum uniformly black, surface microrugose (slightly rugose ‘imitating’ pubescence), predominantly light brown pubescent, broad sublateral stripes (interrupted by transverse suture) and narrow paramedian stripes merging postsuturally and not reaching posterior margin apubescent, scutal setation comprised of long white to yellow setae in pubescent areas; dc setae presuturally white, postsuturally absent, acr setae absent, lateral scutal setae white, npl setae 0, spal setae 0, pal setae 0; proepisternum apubescent medially, grey pubescent laterally, long yellowish macrosetose; proepimeron grey pubescent, asetose, antepronotum antero-medially smooth (without any indentation); lateral postpronotum short yellowish setose; postpronotal lobe yellow, white pubescent, short yellowish setose; scutellum light brown pubescent, discal scutellar setae absent, apical scutellar setae absent; mesopostnotum light brown pubescent, asetose; anatergite light brown pubescent, asetose; katatergite light brown pubescent, long white setose, elevated and smoothly convex; anepisternum light brown pubescent, anteriorly asetose, posteriorly asetose, otherwise asetose; katepisternum light brown pubescent, asetose; anepimeron light brown pubescent, single long yellowish seta dorso-medially; katepimeron light brown pubescent, asetose; meron light brown pubescent, asetose; metakatepisternum large; metanepisternum light brown pubescent, asetose; metepimeron brown (same color as T1), light brown pubescent, short white setose, ± flat, infra-halter sclerite absent.

Legs : light brown to brown, setation comprised of white setae, yellow macrosetae; pro coxa sparsely grey pubescent, long yellowish macrosetose; mes coxa sparsely grey pubescent, long yellowish macrosetose; met coxa laterally unsclerotized (membrane between coxa and metakatepisternum clearly visible), sparsely grey pubescent, long yellowish macrosetose; met trochanter sparsely setose medially; pro + mes femur brown, met femur brown, distinctly clubbed for nearly entire length, macrosetose with thickened spine-like macrosetae on protuberances in 1 antero-ventral and 1 postero-ventral rows, 2–3 macrosetae distally in anterior row, postero-ventrally long white, appressed setose; pro tibia straight; mes tibia straight; met tibia laterally arched, met tibia cylindrical with distinct ventral keel terminating into distinct spur, macroseta at tip of spur, almost reaching tip of 1^st tarsomere, postero-laterally short white, appressed setose; pro + mes tarsomere 1 approximately as long as individual tarsomeres 2, 3, or 4, met tarsomere 1 as long as individual tarsomeres 2, 3, or 4; pulvillus reduced, ½ length of well-developed claw; setiform empodium absent.

Wing : length = 9.9 mm; slightly brown stained throughout, veins brown, microtrichia absent; cells r₁, r₄, m₃, + cua closed, r₅ open; C terminating at junction with R₁; Sc long, terminating in C proximal to r-m; R₄ terminates in R₁; R₅ terminates in R₁; auxiliary vein (R₃) at base of R₄ absent; R₄ and R₅ widest apart medially; r-m distinct, R₄₊₅ and M₁ apart, connected by crossvein; M₁ straight at r-m (not curving anteriorly), M₁ (or M₁+M₂) terminates in C; base of M₃+M₄ present, M₃+M₄ not terminating together in C (not reaching wing margin), M₄ and CuA split proximally to m-cu (cell m₃ narrow proximally); CuP straight, cell cup wide, CuP and wing margin further apart proximally than distally; alula entirely reduced (nearly straight wing margin); halter light brown, pubescent, dorsally asetose, ventrally yellow setose.

Abdomen : brown, setation comprised of scattered short white setae, T2–4 parallel-sided and not constricted waist-like, T surface entirely smooth; T1–6 dark brown with light yellow posterior margin narrowest medially, T7 dark brown; T1–2 sparsely grey pubescent, T3–7 apubescent; T1–7 short white setose; S1–7 brown; S apubescent; S1–7 sparsely short white setose; bullae on T2 oval, small, yellow, surface entirely smooth, T2 surface anterior to bullae smooth.

♀ abdomen and genitalia: densely arranged anteriorly directed setae present on T7–8 and S7–8; T8 anterior apodeme indiscernible (not dissected), auxiliary spiracle indiscernible (not dissected); T9 formed by wide, rectangular sclerite with median protuberance; T9+10 entirely fused (sclerites indistinguishable), T10 divided into 2 heavily sclerotized acanthophorite plates; 6 acanthophorite spines per plate.

Male. Head: black, facial gibbosity yellow, in general densely grey pubescent, white setose, regular, cylindrical setae; width distinctly greater than thorax (at postpronotal lobe), interocular distance on vertex same as at ventral eye margin; vertex between compound eyes ± horizontally straight, medially only slightly below dorsal eye margin, vertex grey pubescent, white setose; ocellar triangle apubescent; facial gibbosity distinct, well-developed and discernible in lateral view, mystax covering entire facial gibbosity, white; parafacial area approximately as wide as ¾ width of central gibbosity (at same level); frons not elevated, grey pubescent, white setose; occiput grey pubescent, white setose, median occipital sclerite yellowish macrosetose; pocl macrosetae absent; postgena sparsely grey pubescent, long, sparsely white setose; clypeus comprised of single sclerite, entirely sclerotized medially, flat to protruding (convex) ventrally, ventrally expanded, anterior to proboscis (almost covering it), laterally connected to face by sclerotized cuticle; proboscis very short, vestigial, knob-like, brown; labellum indiscernible, length indiscernible, sclerotization indiscernible; maxillary palpus cylindrical, brown, longer than proboscis.

Antenna : brown; scape white setose dorsally, asetose ventrally; pedicel white setose dorsally and ventrally; postpedicel cylindrical in proximal ⅓, symmetrically bulbous in distal 2/3, ≥ 3.0 times as long as combined length of scape and pedicel, asetose; apical seta-like sensory element situated apically in cavity on postpedicel.

Thorax : dark brown, predominantly grey pubescent; scutum uniformly black, surface microrugose (slightly rugose ‘imitating’ pubescence), predominantly grey pubescent, broad sublateral stripes (interrupted by transverse suture) and narrow paramedian stripes merging postsuturally and not reaching posterior margin apubescent, scutal setation comprised of long white to yellow setae in pubescent areas; dc setae presuturally white, postsuturally absent, acr setae absent, lateral scutal setae white, npl setae 0, spal setae 0, pal setae 0; proepisternum apubescent medially, grey pubescent laterally, long yellowish macrosetose; proepimeron grey pubescent, asetose, antepronotum antero-medially smooth (without any indentation); lateral postpronotum short yellowish setose; postpronotal lobe yellow, white pubescent, short yellowish setose; scutellum sparsely grey pubescent, discal scutellar setae absent, apical scutellar setae absent; mesopostnotum grey pubescent, asetose; anatergite grey pubescent, asetose; katatergite grey pubescent, long white setose, elevated and smoothly convex; anepisternum sparsely grey pubescent, anteriorly asetose, posteriorly asetose, otherwise asetose; katepisternum sparsely grey pubescent, few white setae posteriorly; anepimeron sparsely grey pubescent, single long yellowish seta dorso-medially; katepimeron sparsely grey pubescent, white setose; meron sparsely grey pubescent, asetose; metakatepisternum large; metanepisternum grey pubescent, asetose; metepimeron brown (same color as T1), grey pubescent, short white setose, ± flat, infra-halter sclerite absent.

Legs : light brown to brown, setation comprised of white setae, yellow macrosetae; pro coxa sparsely grey pubescent, long white macrosetose; mes coxa sparsely grey pubescent, short white setose; met coxa laterally unsclerotized (membrane between coxa and metakatepisternum clearly visible), sparsely grey pubescent, short white setose; met trochanter sparsely setose medially; pro + mes femur brown, met femur brown, distinctly clubbed for nearly entire length, macrosetose with thickened spine-like macrosetae on protuberances in 1 antero-ventral and 1 postero-ventral rows, 2–3 macrosetae distally in anterior row, postero-ventrally long white, appressed setose; pro tibia straight; mes tibia straight; met tibia laterally arched, met tibia cylindrical with distinct ventral keel terminating into distinct spur, spur almost reaching tip of 1^st tarsomere, postero-laterally short white, appressed setose; pro + mes tarsomere 1 approximately as long as individual tarsomeres 2, 3, or 4, met tarsomere 1 as long as individual tarsomeres 2, 3, or 4; pulvillus well-developed, as long as well-developed claw, and as wide as base of claw; setiform empodium absent.

Wing : length = 5.6–7.6 mm; slightly brown stained throughout, veins brown, microtrichia absent; cells r₁, r₄, m₃, + cua closed, r₅ open; C terminating at junction with R₁; Sc long, terminating in C proximal to r-m; R₄ terminates in R₁; R₅ terminates in R₁; auxiliary vein (R₃) at base of R₄ absent; R₄ and R₅ widest apart medially; r-m distinct, R₄₊₅ and M₁ apart, connected by crossvein; M₁ straight at r-m (not curving anteriorly), M₁ (or M₁+M₂) terminates in C; base of M₃+M₄ present, M₃+M₄ not terminating together in C (not reaching wing margin), M₄ and CuA split proximally to m-cu (cell m₃ narrow proximally); CuP straight, cell cup wide, CuP and wing margin further apart proximally than distally; alula entirely reduced (nearly straight wing margin); halter light brown, pubescent, dorsally asetose, ventrally yellow setose.

Abdomen : brown, setation comprised of scattered short white setae, T2–4 parallel-sided and not constricted waist-like, T surface entirely smooth; T1–7 brown with narrow yellow posterior margin; T sparsely grey pubescent; T1–7 short white setose; S1–7 light brown; S apubescent; S1–7 sparsely short white setose; bullae on T2 oval, small, yellow, surface entirely smooth, T2 surface anterior to bullae smooth.

♂ abdomen and terminalia: T1–7 well-developed, entirely sclerotized, T8 postero-medially weakly sclerotized, with anterior transverse sclerotized bridge connecting lateral sclerites; T7–8 anteriorly with 2 lateral apodemes; T8 auxiliary spiracle present; S6 regular, without any special setation postero-medially; S8 simple plate, entire (undivided) ventro-medially, not fused to T8 dorso-laterally; epandrium formed by 2 sclerites, separated medially and fused anteriorly, distally in dorsal view blunt, evenly rounded; subepandrial sclerite without lateral or median protuberances; hypandrium concave, cup-shaped, entirely sclerotized ventrally, entirely fused with gonocoxite, forming a gonocoxite-hypandrial complex, supra-hypandrial sclerite absent; gonocoxite simple, short, hook-like, without median or lateral protuberance, gonocoxal apodeme absent; 2 functional phallic prongs, short and wide, medio-distally connected, parallel or diverging laterally, distally straight or only diverging slightly laterally; phallic epimere absent; lateral ejaculatory process absent; ejaculatory apodeme formed by single dorso-ventrally oriented plate; ventro-median margin of parameral sheath heavily sclerotized (appearing entirely closed); parameral sheath long, sperm sac entirely covered; sperm sac appearing weakly sclerotized.

Namibia: Kunene: Orupembe (= Anabib), 24 km S (18°23'00"S, 012°13'00"E, -18.38333, 12.21667).

Namibia: Kunene: 1♀ Kaokoveld, Orupembe, 24 km S, 18°21'21"S, 012°28'35"E, 1951-06-09, Swedish South Africa Expedition (MZLU-2143:1, Holotype, MZLU); 2♂ Kaokoveld, Orupembe, 18°09'37"S, 012°33'44"E, 1951-06-07–1951-06-09, Swedish South Africa Expedition (MZLU-2143:2, MZLU-2143:3, Paratypes, MZLU).

Known only from two localities in the northern Namib Desert in Namibia (Fig. 56). A rarely collected species known only from three specimens from two collecting events in 1951 (Table 1). The species is not known to occur in any currently recognized biodiversity hotspot. Adult flies are active in June in early winter (Table 2), which is a time following a moister period and lower temperatures in this part of the Namib Desert (data for Anabib, Namibia, see https://www.worldweatheronline.com/anabib-weather/kunene/na.aspx). Nothing is known of the biology.

The size difference among the three known specimens is quite significant. The ♀ holotype (wing length 9.9 mm) is much larger than the two ♂ paratypes (wing length 5.6–7.7 mm) and represents the largest fly in the genus Eremohaplomydas.

The species is distinguished from congeners by the densely arranged dorso-ventrally flattened setae on legs, the absence of the base of vein M₃+M₄, the overall golden pubescence, and the restricted distribution in the central Namib Desert.

This species is named after the Gobabeb Namib Research Institute (www.gobabeb.org) where it was collected for the first time in November 2018. The specific epithet is to be treated as a noun in apposition.

Female. unknown.

Male. Head: black, facial gibbosity brown, in general golden pubescent, ventrally and posteriorly white pubescent, white setose, laterally compressed setae; width distinctly greater than thorax (at postpronotal lobe), interocular distance on vertex larger than at ventral eye margin; vertex between compound eyes ± horizontally straight, medially only slightly below dorsal eye margin, vertex golden pubescent, white setose; ocellar triangle apubescent; facial gibbosity distinct, well-developed and discernible in lateral view, mystax covering entire facial gibbosity, white; parafacial area approximately as wide as ½ width of central facial gibbosity (at same level); frons not elevated, golden pubescent, white setose; occiput predominantly white pubescent, dorsally golden pubescent, white setose, median occipital sclerite white setose, laterally compressed setae; pocl macrosetae absent; postgena apubescent, long, sparsely white setose; clypeus comprised of inverted U-shaped sclerite, dorsal ½ sclerotized medially to form plate, recessed (concave), ventrally simple, posterior to proboscis, laterally connected to face by sclerotized cuticle; proboscis very short, vestigial, knob-like, yellow; labellum small, as wide as prementum, length indiscernible, sclerotization indiscernible; maxillary palpus laterally compressed (triangular), light brown, slightly longer than proboscis.

Antenna : light brown to brown; scape white setose dorsally, asetose ventrally; pedicel white setose dorsally and ventrally; postpedicel cylindrical in proximal 1/5, symmetrically bulbous in distal 4/5, ≥ 5.0 times as long as combined length of scape and pedicel, asetose; apical seta-like sensory element situated apically in cavity on postpedicel.

Thorax : brown, scutum golden pubescent, pleura white pubescent; scutum uniformly black, surface entirely smooth, golden pubescent, scutal setation comprised of long white setae with distinct rows of long dorsocentral setae and dense lateral scutal setae; dc setae pre- and postsuturally white, acr setae absent, lateral scutal setae white, npl setae 0, spal setae 0, pal setae 0; proepisternum apubescent, long white setose; proepimeron grey pubescent, asetose; antepronotum antero-medially smooth (without any indentation); lateral postpronotum long white setose; postpronotal lobe light brown, golden to light brown pubescent, long white setose; scutellum golden pubescent, discal scutellar setae absent, apical scutellar setae absent; mesopostnotum golden pubescent, asetose; anatergite golden pubescent, asetose; katatergite white pubescent, long white setose, slightly elevated, smoothly convex; anepisternum white pubescent, anteriorly white setose, posteriorly densely long white setose, scattered long white setose centrally; katepisternum dorsally white pubescent, ventrally apubescent, asetose; anepimeron white pubescent, long white setose; katepimeron white pubescent, asetose; meron white pubescent dorsally, sparsely white pubescent ventrally, asetose; metakatepisternum large; metanepisternum white pubescent, asetose; metepimeron yellow (same color as T1), white pubescent, long white setose, ± flat, infra-halter sclerite absent.

Legs : light brown to brown, setation comprised of white laterally compressed setae predominantly covering surface; pro coxa apubescent, sparse white laterally compressed setae; mes coxa apubescent, asetose anteriorly, short white laterally compressed setae posteriorly; met coxa laterally unsclerotized (membrane between coxa and metakatepisternum clearly visible), apubescent, asetose anteriorly, short white laterally compressed setae posteriorly; met trochanter setose medially; pro + mes femur light brown to brown, met femur light brown to brown, distinctly clubbed for nearly entire length, macrosetose, 1 antero-ventral and 1 postero-ventral row of macrosetae, postero-ventrally long white, appressed setose; pro tibia laterally arched; mes tibia laterally arched; met tibia laterally arched, met tibia cylindrical with ventral keel terminating into distinct spur, spur not projecting beyond tip of tibia, postero-laterally long white, appressed setose; pro + mes tarsomere 1 approximately as long as individual tarsomeres 2, 3, or 4, met tarsomere 1 as long as individual tarsomeres 2, 3, or 4; pulvillus well-developed, as long as well-developed claw, and as wide as base of claw; setiform empodium absent.

Wing : length = 4.2–5.7 mm; hyaline throughout, veins light yellow, microtrichia absent; cells r₁, r₄, m₃, + cua closed, r₅ open; C terminating at junction with R₁; Sc long, terminating in C proximal to r-m; R₄ terminates in R₁; R₅ terminates in R₁ and R₄ simultaneously; auxiliary vein (R₃) at base of R₄ absent; R₄ and R₅ widest apart medially; r-m distinct, R₄₊₅ and M₁ apart, connected by crossvein; M₁ curves slightly anteriorly at r-m, M₁ (or M₁+M₂) terminates in C (not reaching wing margin); base of M₃+M₄ absent, M₃+M₄ not terminating together in C (not reaching wing margin), M₄ and CuA split proximally to m-cu (cell m₃ narrow proximally); CuP straight, cell cup wide, CuP and wing margin further apart proximally than distally; alula well-developed; halter light yellow, apubescent, asetose.

Abdomen : light brown to brown, setation comprised of dense long white setae, T2–4 parallel-sided and not constricted waist-like, T surface entirely smooth; T1–4 light brown, T5–7 brown; T entirely golden pubescent; T1–7 long white setose; S1–5 brown with white posterior margin, S6–7 dark brown; S apubescent; S1 asetose, S2–7 long white setose; bullae on T2 oval, brown, surface entirely smooth, T2 surface anterior to bullae smooth.

♂ abdomen and terminalia: T1–8 well-developed; T7–8 anteriorly with 2 lateral apodemes; S6 regular, without any special setation postero-medially; S8 simple plate, entire (undivided) ventro-medially, not fused to T8 dorso-laterally; epandrium formed by single sclerite (fused medially ± entirely), distally in dorsal view pointed postero-laterally; subepandrial sclerite without lateral or median protuberances; hypandrium ± flat, divided ventro-medially by unsclerotized area into 2 sclerotized halves, entirely fused with gonocoxite, forming a gonocoxite-hypandrial complex, supra-hypandrial sclerite absent; gonocoxite simple, short, hook-like, without median or lateral protuberance, gonocoxal apodeme absent; 2 functional phallic prongs, short with broad lateral flange, medio-distally connected, parallel or diverging laterally, distally straight or only diverging slightly laterally; phallic epimere absent; lateral ejaculatory process absent; ejaculatory apodeme formed by single dorso-ventrally oriented plate; ventro-median margin of parameral sheath heavily sclerotized (appearing entirely closed); parameral sheath long, sperm sac entirely covered; sperm sac appearing ± heavily sclerotized.

Namibia: Erongo: Namib-Naukluft National Park, Gobabeb 20 km NW on D1983, Kuiseb riverbed (23°24'56"S, 014°54'43"E, -23.41556, 14.91194).

Namibia: Erongo: 1♂ Namib-Naukluft National Park, Gobabeb 20 km NW on D1983, Kuiseb riverbed, 23°24'56"S, 014°54'43"E, 317 m, 2018-11-24 collected a.m. (9:00–noon), dry, sandy, partly wooded riverbed, resting on sand, Dikow, T. (USNMENT01518262, Holotype, NMNW); 1♂ Namib-Naukluft National Park, Gobabeb 20 km NW on D1983, Kuiseb riverbed, 23°24'56"S, 014°54'43"E, 317 m, 2018-11-24 collected a.m. (9:00–noon), dry, sandy, partly wooded riverbed, resting on sand, Dikow, T. (USNMENT01518263, Paratype, NMNW); 1♂ Namib-Naukluft National Park, Gobabeb 20 km NW on D1983, Kuiseb riverbed, 23°24'56"S, 014°54'43"E, 317 m, 2018-11-24 collected a.m. (9:00–noon), dry, sandy, partly wooded riverbed, resting on sand, Dikow, T. (USNMENT01518261, Paratype, USNM); 1♂ Namib-Naukluft National Park, Gobabeb 20 km NW on D1983, Kuiseb riverbed, 23°24'56"S, 014°54'43"E, 317 m, 2018-11-24 collected a.m. (9:00–noon), dry, sandy, partly wooded riverbed, resting on sand, Dikow, T. (USNMENT01518260, Paratype, USNM); 1♂ Namib-Naukluft National Park, Gobabeb, dunes W of Kuiseb riverbed, 23°33'48"S, 015°01'58"E, 401 m, 2018-11-21 collected a.m. (9:00–noon), small vegetated dunes, resting on sand, Dikow, T. (USNMENT01518012, Paratype, USNM); 1♂ Namib-Naukluft National Park, Gobabeb, small dunes W of Kuiseb River, 23°33'50"S, 015°01'59"E, 398 m, 2018-11-23 collected p.m. (noon–15:00), partly vegetated dune, resting on sand, Dikow, T. (USNMENT01518339, Paratype, USNM).

Known only from two localities in the central Namib Desert in Namibia (Fig. 56). A rarely collected species known only from seven specimens from three collecting events in 2018 (Table 1). The species is not known to occur in any currently recognized biodiversity hotspot. Adult flies are active in November in late spring (Table 2), which is a time at the beginning of a moister period and rising temperatures in this part of the Namib Desert (data for Gobabeb, Namibia, see https://www.worldweatheronline.com/gobabeb-weather/erongo/na.aspx). So far, only males have been collected and they were observed to fly very low above the ground and appeared to inspect the base of single grass plants and dart at high speed across the sand to the next plant. At the Gobabeb locality, the flies were collected flying among Centropodia glauca (Poaceae, Gha Grass, https://www.gbif.org/species/5680035) and at the 20 km N Gobabeb locality the flies darted among Cladoraphis spinosa (Poaceae, Spiny Love Grass, https://www.gbif.org/species/4152290, see habitat photographs with the grasses in the foreground in Figs 1, 2). Both grass species are native and widely distributed in the western parts of southern Africa including the Namib Desert (van Oudtshoorn 2012). The male flies possibly inspected the grasses in search for females resting in the shade although the junior author was not able to observe or collect any females. In general, the flies were very difficult to observe and collect due to their high flight speed, light colouration, and small size.

Wharton (1982) did not collect this species in his seminal year-long study of Mydidae at Gobabeb.

The species is distinguished from congeners by the macrosetose dorso-median occipital setae, the small and slender size (wing length 6.3 mm), and the restricted distribution in the northern Namib Desert.

Greek stoma = mouth, choris = without. The specific epithet refers to the extremely short and minute proboscis in this species.

Female. Head: black, facial gibbosity brown, in general golden pubescent, ventrally and posteriorly white pubescent, white setose, regular, cylindrical setae; width distinctly greater than thorax (at postpronotal lobe), interocular distance on vertex larger than at ventral eye margin; vertex between compound eyes ± horizontally straight, medially only slightly below dorsal eye margin, vertex golden pubescent, light brown; ocellar triangle apubescent; facial gibbosity distinct, well-developed and discernible in lateral view, mystax covering entire facial gibbosity, sparse, white; parafacial area approximately as wide as ½ width of central facial gibbosity (at same level); frons not elevated, golden pubescent, yellow; occiput predominantly grey pubescent, dorsally golden pubescent, yellowish to light brown setose, median occipital sclerite yellowish macrosetose; pocl macrosetae absent; postgena sparsely white pubescent, long, sparsely white setose; clypeus comprised of single sclerite, entirely sclerotized medially, flat to protruding (convex) ventrally, ventrally simple, posterior to proboscis, laterally connected to face by sclerotized cuticle; proboscis very short, vestigial, knob-like, light brown; labellum small, as wide as prementum, length indiscernible, sclerotization indiscernible; maxillary palpus laterally compressed (triangular), light brown, slightly longer than proboscis.

Antenna : brown; scape brown setose dorsally, asetose ventrally; pedicel light brown setose dorsally and ventrally; postpedicel cylindrical in proximal ¼, symmetrically bulbous in distal ¾, ≥ 4.0 times as long as combined length of scape and pedicel, asetose; apical seta-like sensory element situated apically in cavity on postpedicel.

Thorax : light brown, predominantly grey pubescent; scutum black, brown posteriorly, surface entirely smooth, predominantly grey pubescent, broad median and sublateral stripes reaching transverse suture brown pubescent, postsuturally with 2 large sublateral sparsely grey pubescent spots, scutal setation comprised of distinct rows of long dorsocentral setae and lateral scutal setae; dc setae pre- and postsuturally white or yellow, acr setae absent, lateral scutal setae yellow, npl setae 0, spal setae 0, pal setae 0; proepisternum apubescent, long white setose; proepimeron grey pubescent, asetose; antepronotum antero-medially smooth (without any indentation); lateral postpronotum long white setose; postpronotal lobe yellow, white pubescent, long white setose; scutellum grey pubescent, discal scutellar setae absent, apical scutellar setae absent; mesopostnotum grey pubescent, asetose; anatergite grey pubescent, asetose; katatergite grey pubescent, long white setose, slightly elevated, smoothly convex; anepisternum grey pubescent, anteriorly white setose, posteriorly long white setose, scattered white setose antero-ventrally; katepisternum dorsally grey pubescent, ventrally apubescent, single white seta posteriorly; anepimeron grey pubescent, long white setose; katepimeron grey pubescent, asetose; meron grey pubescent dorsally, apubescent ventrally, asetose; metakatepisternum large; metanepisternum grey pubescent, asetose; metepimeron yellow (contrasting color of T1), grey pubescent, long white setose, ± flat, infra-halter sclerite absent.

Legs : light brown to brown, setation comprised of white to yellowish setae, femur with laterally compressed setae; pro coxa sparsely white pubescent, short white macrosetose; mes coxa sparsely white pubescent, short white macrosetose anteriorly, long white laterally compressed setae posteriorly; met coxa laterally unsclerotized (membrane between coxa and metakatepisternum clearly visible), sparsely white pubescent, short white macrosetose anteriorly, long white laterally compressed setae posteriorly; met trochanter sparsely setose medially; pro + mes femur light brown to brown, met femur light brown to brown, evenly clubbed in distal ¾, macrosetose, 1 antero-ventral and 1 postero-ventral row of macrosetae, postero-ventrally long white, appressed setose; pro tibia laterally arched; mes tibia laterally arched; met tibia straight, met tibia cylindrical with distinct ventral keel without terminal spur, 2 long macrosetae originating near tip of keel, postero-laterally regular setose only; pro + mes tarsomere 1 approximately as long as individual tarsomeres 2, 3, or 4, met tarsomere 1 as long as individual tarsomeres 2, 3, or 4; pulvillus well-developed, as long as well-developed claw, and as wide as base of claw; setiform empodium absent.

Wing : length = 6.3 mm; hyaline throughout, veins light brown, microtrichia absent; cells r₁, r₄, m₃, + cua closed, r₅ open; C terminating at junction with R₁; Sc long, terminating in C proximal to r-m; R₄ terminates in R₁; R₅ terminates in R₁ and R₄ simultaneously; auxiliary vein (R₃) at base of R₄ absent; R₄ and R₅ widest apart medially; r-m distinct, R₄₊₅ and M₁ apart, connected by crossvein; M₁ straight at r-m (not curving anteriorly), M₁ (or M₁+M₂) terminates in C (not reaching wing margin); base of M₃+M₄ present, M₃+M₄ not terminating together in C (not reaching wing margin), M₄ and CuA split proximally to m-cu (cell m₃ narrow proximally); CuP straight, cell cup wide, CuP and wing margin further apart proximally than distally; alula well-developed; halter light yellow, apubescent, asetose.

Abdomen : light brown to brown, setation comprised of scattered white setae, T2–4 parallel-sided and not constricted waist-like, T surface entirely smooth; T1 brown with yellowish posterior margin, T2–7 brown medially and laterally with yellowish posterior margins, sub-laterally yellowish, slightly angled longitudinal striping; T1 grey pubescent, T2–3 sparsely grey pubescent narrowly anteriorly and medially, T4–7 apubescent; T1–7 short white setose; S1–7 light brown; S apubescent; S1–7 sparsely short white setose; bullae on T2 oval, small, yellow, surface entirely smooth, T2 surface anterior to bullae smooth.

♀ abdomen and genitalia: densely arranged anteriorly directed setae present on T7–8 and S7–8; T8 anterior apodeme indiscernible (not dissected), auxiliary spiracle indiscernible (not dissected); T9 formed by wide, rectangular sclerite with median protuberance; T9+10 entirely fused (sclerites indistinguishable), T10 divided into 2 heavily sclerotized acanthophorite plates; 5–7 acanthophorite spines per plate.

Male. unknown.

Namibia: Kunene: Kaokoveld, Orupembe, 21 km S (18°19'24"S, 012°29'12"E, -18.32333, 12.48667).

Namibia: Kunene: 1♀ Kaokoveld, Orupembe, 21 km S, 18°19'24"S, 012°29'12"E, 1970-05-01, Brown, H. (AAM-003035, Holotype, SANC).

Known only from a single locality in the Namib Desert in northern Namibia (Fig. 57). A rarely collected species known only from a single female specimen collected in 1970 (Table 1). The species is not known to occur in any currently recognized biodiversity hotspot. Adult flies are active in May in mid-autumn (Table 2), which is a time at the end of a moister period and decreasing temperatures in this part of the Namib Desert (data for Anabib, Namibia, see https://www.worldweatheronline.com/anabib-weather/kunene/na.aspx). Nothing is known of the biology.

The type locality of Eremohaplomydas stomachoris sp. nov. lies geographically very close to that of Eremohaplomydas desertorum. However, the single female specimen of E. stomachoris sp. nov. is morphologically more similar to Eremohaplomydas gobabebensis sp. nov. from the central Namib Desert (more than 600 km further south) than it is to E. desertorum (see also Discussion). Furthermore, E. stomachoris sp. nov. has been collected in early May, at least a month earlier in autumn than E. desertorum (Table 2).

The species is distinguished from congeners by the overall light brown colouration, the reduced alula on the wing, the apubescent abdominal tergites 5–8 in females, and the restricted distribution in the central Namib Desert.

This species is named after Dr Robert Wharton, the only collector of this species, in recognition of his year-long seminal study of the Mydidae (and other taxa) of the central Namib Desert at the Gobabeb Namib Research Institute in 1978–1979 (Wharton 1982). The specific name is to be treated as a noun in apposition.

Female. Head: black, facial gibbosity light brown, in general grey pubescent, white setose, regular, cylindrical setae; width distinctly greater than thorax (at postpronotal lobe), interocular distance on vertex same as at ventral eye margin; vertex between compound eyes ± horizontally straight, medially only slightly below dorsal eye margin, vertex grey pubescent, white setose; ocellar triangle apubescent; facial gibbosity distinct, well-developed and discernible in lateral view, mystax covering entire facial gibbosity, white; parafacial area more than ½ width of central facial gibbosity (at same level); frons not elevated, grey pubescent, white setose; occiput grey pubescent, white setose, median occipital sclerite light brown macrosetose; pocl macrosetae absent; postgena sparsely grey pubescent, long, sparsely white setose; clypeus comprised of single sclerite, entirely sclerotized medially, flat to protruding (convex) ventrally, ventrally expanded, anterior to proboscis (almost covering it), laterally connected to face by sclerotized cuticle; proboscis very short, vestigial, knob-like, brown; labellum indiscernible, length indiscernible, sclerotization indiscernible; maxillary palpus cylindrical, light brown, minute.

Antenna : light brown to brown; scape asetose; pedicel white setose dorsally and ventrally; postpedicel cylindrical in proximal ¼, symmetrically bulbous in distal ¾, ≥ 5.0 times as long as combined length of scape and pedicel, asetose; apical seta-like sensory element situated apically in cavity on postpedicel.

Thorax : dark brown, predominantly grey pubescent; scutum uniformly black, surface microrugose (slightly rugose ‘imitating’ pubescence), predominantly grey pubescent, broad sublateral stripes (interrupted by transverse suture) sparsely grey pubescent, narrow paramedian stripes merging postsuturally and not reaching posterior margin sparsely grey pubescent, scutal setation comprised of long white setae in pubescent areas; dc setae pre- and postsuturally white, acr setae absent, lateral scutal setae white, npl setae 0, spal setae 0, pal setae 0; proepisternum apubescent medially, grey pubescent laterally, long yellowish macrosetose; proepimeron grey pubescent, asetose; antepronotum antero-medially smooth (without any indentation); lateral postpronotum long white setose; postpronotal lobe yellow, grey pubescent, short yellowish setose; scutellum grey pubescent, discal scutellar setae absent, apical scutellar setae absent; mesopostnotum grey pubescent, asetose; anatergite grey pubescent, asetose; katatergite grey pubescent, long white setose, elevated and smoothly convex; anepisternum grey pubescent, anteriorly asetose, posteriorly asetose, otherwise asetose; katepisternum sparsely grey pubescent, asetose; anepimeron sparsely grey pubescent, asetose; katepimeron sparsely grey pubescent, asetose; meron sparsely grey pubescent, asetose; metakatepisternum large; metanepisternum grey pubescent, asetose; metepimeron light brown (same color as T1), grey pubescent, long yellowish setose, ± flat, infra-halter sclerite absent.

Legs : yellow to brown, setation comprised of white setae, yellow macrosetae; pro coxa sparsely grey pubescent, short white macrosetose; mes coxa sparsely grey pubescent, short white setose and macrosetose; met coxa laterally unsclerotized (membrane between coxa and metakatepisternum clearly visible), sparsely grey pubescent, short white setose and macrosetose; met trochanter setose medially; pro + mes femur yellow to light brown, met femur light brown to brown, distinctly clubbed for nearly entire length, macrosetose with thickened spine-like macrosetae on protuberances in 1 antero-ventral and 1 postero-ventral rows, 2–3 macrosetae distally in anterior row, postero-ventrally sparse, short white setose; pro tibia laterally arched; mes tibia laterally arched; met tibia laterally arched, met tibia cylindrical with distinct ventral keel terminating into distinct spur, macroseta at tip of spur, almost reaching tip of 1^st tarsomere, postero-laterally sparse long white, erect setose with setae arranged in distinct row; pro + mes tarsomere 1 as long as tarsomere 2, met tarsomere 1 as long as individual tarsomeres 2, 3, or 4; pulvillus reduced, ½ length of well-developed claw; setiform empodium absent.

Wing : length = 7.0–7.9 mm; hyaline throughout, veins light brown, microtrichia absent; cells r₁, r₄, m₃, + cua closed, r₅ open; C terminating at junction with R₁; Sc long, terminating in C proximal to r-m; R₄ terminates in R₁; R₅ terminates in R₁; auxiliary vein (R₃) at base of R₄ absent; R₄ and R₅ widest apart medially; r-m distinct, R₄₊₅ and M₁ apart, connected by crossvein; M₁ straight at r-m (not curving anteriorly), M₁ (or M₁+M₂) terminates in C (not reaching wing margin), rarely C; base of M₃+M₄ present, M₃+M₄ not terminating together in C (not reaching wing margin), M₄ and CuA split proximally to m-cu (cell m₃ narrow proximally); CuP straight, cell cup wide, CuP and wing margin further apart proximally than distally; alula entirely reduced (nearly straight wing margin); halter light brown, apubescent, dorsally asetose, ventrally yellow setose.

Abdomen : light brown to brown, setation comprised of scattered short white setae, T2–4 parallel-sided and not constricted waist-like, T surface entirely smooth; T1–4 light brown with narrow yellowish posterior margins, T5–7 brown with narrow yellowish posterior margins; T1–4 grey pubescent, T5 sparsely grey pubescent medially, T6–7 apubescent; T1 short white setose, T2–6 sparsely very short white setose, T7 short erect white setose; S1 light brown, S2–3 brown with yellowish posterior margins, S4–7 brown; S apubescent; S1–7 sparsely short white setose; bullae on T2 transversely elongate, yellow, surface entirely smooth, T2 surface anterior to bullae smooth.

♀ abdomen and genitalia: densely arranged anteriorly directed setae present on T7–8 and S7–8; T8 anterior apodeme present, broad and rectangular, auxiliary spiracle present; T9 formed by wide, rectangular sclerite with median protuberance; T9+10 entirely fused (sclerites indistinguishable), T10 divided into 2 heavily sclerotized acanthophorite plates; 6 acanthophorite spines per plate; 2 spermathecae, all equally large, not differentiated from spermathecal ducts, weakly sclerotized; individual spermathecal duct short; S9 (furca) formed by 1 sclerite, inverted U-shaped (joined anteriorly, separated posteriorly), anterior furcal apodeme present, 2 lateral projections forming divided apodeme, lateral furcal apodeme absent, median furcal bridge absent.

Male. Head: black, facial gibbosity brown, in general grey pubescent, white setose, regular, cylindrical setae; width distinctly greater than thorax (at postpronotal lobe), interocular distance on vertex same as at ventral eye margin; vertex between compound eyes ± horizontally straight, medially only slightly below dorsal eye margin, vertex grey pubescent, white setose; ocellar triangle apubescent; facial gibbosity distinct, well-developed and discernible in lateral view, mystax covering entire facial gibbosity, white; parafacial area approximately as wide as ½ width of central facial gibbosity (at same level); frons not elevated, grey pubescent, white setose; occiput grey pubescent, white setose, median occipital sclerite light brown macrosetose; pocl macrosetae absent; postgena sparsely grey pubescent, long, sparsely white setose; clypeus comprised of single sclerite, entirely sclerotized medially, flat to protruding (convex) ventrally, ventrally expanded, anterior to proboscis (almost covering it), laterally connected to face by sclerotized cuticle; proboscis very short, vestigial, knob-like, brown; labellum indiscernible, length indiscernible, sclerotization indiscernible; maxillary palpus cylindrical, light brown, minute.

Antenna : light brown to brown; scape white setose dorsally, asetose ventrally; pedicel white setose dorsally and ventrally; postpedicel cylindrical in proximal ⅓, symmetrically bulbous in distal 2/3, ≥ 3.0 times as long as combined length of scape and pedicel, asetose; apical seta-like sensory element situated apically in cavity on postpedicel.

Thorax : black, predominantly grey pubescent; scutum uniformly black, surface microrugose (slightly rugose ‘imitating’ pubescence), predominantly grey pubescent, broad sublateral stripes (interrupted by transverse suture) and narrow paramedian stripes merging postsuturally and not reaching posterior margin apubescent, scutal setation comprised of long white setae in pubescent areas; dc setae pre- and postsuturally white, acr setae absent, lateral scutal setae white, npl setae 0, spal setae 0, pal setae 0; proepisternum apubescent medially, grey pubescent laterally, long yellowish macrosetose; proepimeron grey pubescent, asetose; antepronotum antero-medially smooth (without any indentation); lateral postpronotum long white setose; postpronotal lobe light brown, grey pubescent, short yellowish setose; scutellum grey pubescent, discal scutellar setae absent, apical scutellar setae absent; mesopostnotum grey pubescent, asetose; anatergite grey pubescent, asetose; katatergite grey pubescent, long white setose, elevated and smoothly convex; anepisternum grey pubescent, anteriorly asetose, posteriorly asetose, otherwise asetose; katepisternum grey pubescent, asetose; anepimeron grey pubescent, single long yellowish seta dorso-medially; katepimeron grey pubescent, asetose; meron grey pubescent, asetose; metakatepisternum large; metanepisternum grey pubescent, asetose; metepimeron brown (same color as T1), grey pubescent, long white setose, ± flat, infra-halter sclerite absent.

Legs : brown, setation comprised of white setae, yellow macrosetae; pro coxa sparsely grey pubescent, short white macrosetose; mes coxa sparsely grey pubescent, short white setose; met coxa laterally unsclerotized (membrane between coxa and metakatepisternum clearly visible), sparsely grey pubescent, short white setose; met trochanter setose medially; pro + mes femur brown, met femur brown, distinctly clubbed for nearly entire length, macrosetose with thickened spine-like macrosetae on protuberances in 1 antero-ventral and 1 postero-ventral rows, 2–3 macrosetae distally in anterior row, postero-ventrally sparse, long white erect setose; pro tibia laterally arched; mes tibia laterally arched; met tibia laterally arched, met tibia cylindrical with distinct ventral keel terminating into distinct spur, macroseta at tip of spur, almost reaching tip of 1^st tarsomere, postero-laterally sparse long white, erect setose with setae arranged in distinct row; pro + mes tarsomere 1 as long as tarsomere 2, met tarsomere 1 as long as individual tarsomeres 2, 3, or 4; pulvillus well-developed, as long as well-developed claw, and as wide as base of claw; setiform empodium absent.

Wing : length = 5.0–7.0 mm; hyaline throughout, veins light brown, microtrichia absent; cells r₁, r₄, m₃, + cua closed, r₅ open; C terminating at junction with R₁; Sc long, terminating in C proximal to r-m; R₄ terminates in R₁; R₅ terminates in R₁; auxiliary vein (R₃) at base of R₄ absent; R₄ and R₅ widest apart medially; r-m distinct, R₄₊₅ and M₁ apart, connected by crossvein; M₁ straight at r-m (not curving anteriorly), M₁ (or M₁+M₂) terminates in C (not reaching wing margin), rarely C; base of M₃+M₄ present, M₃+M₄ not terminating together in C (not reaching wing margin), M₄ and CuA split proximally to m-cu (cell m₃ narrow proximally); CuP straight, cell cup wide, CuP and wing margin further apart proximally than distally; alula entirely reduced (nearly straight wing margin); halter light brown, apubescent, dorsally asetose, ventrally yellow setose.

Abdomen : brown, setation comprised of scattered short white setae, T2–4 parallel-sided and not constricted waist-like, T surface entirely smooth; T1–7 brown with yellow posterior margins, dark brown lateral margins; T entirely grey pubescent; T1–7 short white setose; S1 brown, S2–6 brown with yellow posterior margins, S7 brown; S apubescent; S1–7 short white setose; bullae on T2 oval, small, yellow, surface entirely smooth, T2 surface anterior to bullae smooth.

♂ abdomen and terminalia: T1–7 well-developed, entirely sclerotized, T8 postero-medially weakly sclerotized, with anterior transverse sclerotized bridge connecting lateral sclerites; T7–8 anteriorly with 2 lateral apodemes; T8 auxiliary spiracle present; S6 regular, without any special setation postero-medially; S8 simple plate, entire (undivided) ventro-medially, not fused to T8 dorso-laterally; epandrium formed by 2 sclerites, separated medially and fused anteriorly, distally in dorsal view blunt, evenly rounded; subepandrial sclerite without lateral or median protuberances; hypandrium concave, cup-shaped, entirely sclerotized ventrally, entirely fused with gonocoxite, forming a gonocoxite-hypandrial complex, supra-hypandrial sclerite absent; gonocoxite simple, long, slightly curved dorsally, without median or lateral protuberance, gonocoxal apodeme absent; 2 functional phallic prongs, short and wide, medio-distally connected, parallel or diverging laterally, distally straight or only diverging slightly laterally; phallic epimere absent; lateral ejaculatory process absent; ejaculatory apodeme formed by single dorso-ventrally oriented plate; ventro-median margin of parameral sheath heavily sclerotized (appearing entirely closed); parameral sheath long, sperm sac entirely covered; sperm sac appearing ± heavily sclerotized.

Namibia: Erongo: Gobabeb, 5 km N (23°30'54"S, 015°02'35"E, -23.515, 15.04306).

Namibia: Erongo: 1♂ Gobabeb, 5 km N, 23°30'54"S, 015°02'35"E, 1979-05-08, Wharton, R. (NMSA-DIP-92011, Holotype, NMSA); 1♂ Gobabeb, 5 km N, 23°30'54"S, 015°02'35"E, 1979-05-08, Wharton, R. (NMSA-DIP-52603, Paratype, NMSA); 1♂ Gobabeb, plains, 23°33'20"S, 015°02'40"E, 1979-05-12, Wharton, R. (AAM-007357, Paratype, NMNW); 1♂ Gobabeb, plains, 23°33'20"S, 015°02'40"E, 1979-05-12, Wharton, R. (NMSA-DIP-52577, Paratype, NMSA); 1♀ Gobabeb, plains, 23°33'20"S, 015°02'40"E, 1979-05-12, Wharton, R. (NMSA-DIP-92012, Paratype, NMSA); 1♀ Gobabeb, plains, 23°33'20"S, 015°02'40"E, 1979-05-14, Wharton, R. (NMSA-DIP-52578, Paratype, NMSA); 1♂ Gobabeb, plains, 23°33'20"S, 015°02'40"E, 1979-05-11, Wharton, R. (NMSA-DIP-52599, Paratype, NMSA).

Known only from two nearby localities in the central Namib Desert in Namibia (Fig. 57). A rarely collected species known only from seven specimens from three collecting events in 1979 (Table 1). The species is not known to occur in any currently recognized biodiversity hotspot. Adult flies are active in May in mid-autumn (Table 2), which is after a usually moister period and high temperatures in this part of the Namib Desert (data for Gobabeb, Namibia, see www.worldweatheronline.com/gobabeb-weather-averages/erongo/na.aspx). Wharton (1982, p. 149) stated that he observed an attempted mating by two males with the same female at 13 h 00 on 1979-05-12, which was unsuccessful due to interference (female specimen NMSA-DIP-92012 and male specimens AAM-007357 and NMSA-DIP-52577 (Wharton number 332)). Wharton (1982) furthermore highlighted the fact that E. whartoni sp. nov. might only emerge as an imago following the onset of strong autumn winds.

Wharton (1982) in his seminal year-long study of Mydidae at Gobabeb discovered this species for the first time (identified as Eremohaplomydas sp.) and remains the only collector.

The genus can be delineated by the greatly expanded metathoracic femora, the distinct ventral keel terminating into a spur on the metathoracic tibiae, the presence of setae on the posterior anepisternum, the yellow to light brown colouration, and the absence of M₃+M₄ terminating into the costa.

Known from diverse localities in Botswana, Mozambique, Namibia, and Zimbabwe (Fig. 57). A relatively commonly collected genus with collecting events between 1917 and 1999 (Table 1). The genus occurs in the Eastern Afromontane biodiversity hotspot in eastern-most Zimbabwe (Fig. 57). Adult flies are active in late summer to autumn (Table 2). Nothing is known of the biology.

See above for genus.

Female. Head: brown, facial gibbosity yellow, in general densely white pubescent, white setose, regular, cylindrical setae; width distinctly greater than thorax (at postpronotal lobe), interocular distance on vertex larger than at ventral eye margin; vertex between compound eyes ± horizontally straight, medially only slightly below dorsal eye margin, vertex medially apubescent, laterally white pubescent, white setose; ocellar triangle apubescent; facial gibbosity distinct, well-developed and discernible in lateral view, mystax covering entire facial gibbosity, white; parafacial area approximately as wide as ½ width of central facial gibbosity (at same level); frons not elevated, medially apubescent, laterally white pubescent, medially asetose, latero-ventrally white; occiput grey pubescent, white setose, median occipital sclerite brown macrosetose; pocl macrosetae absent; postgena sparsely grey pubescent, long, sparsely white setose; clypeus comprised of single sclerite, entirely sclerotized medially, recessed (concave), ventrally simple, posterior to proboscis, laterally connected to face by membranous cuticle; proboscis long, reaching fronto–clypeal suture, brown; labellum large, much wider than prementum, as long as prementum, unsclerotized laterally; maxillary palpus laterally compressed, bilobed apically, light brown, approximately ⅓ length of proboscis.

Antenna : brown; scape white setose dorsally, asetose ventrally; pedicel white setose dorsally and ventrally; postpedicel cylindrical in proximal ⅓, symmetrically bulbous in distal 2/3, ≥ 4.0 times as long as combined length of scape and pedicel, asetose; apical seta-like sensory element situated apically in cavity on postpedicel.

Thorax : brown, predominantly grey pubescent; scutum predominantly black, surface microrugose (slightly rugose ‘imitating’ pubescence), grey pubescent except for brown pubescent broad median stripe (not reaching posterior margin) and sublateral stripes (interrupted by transverse suture), scutal setation comprised of short white setae in primarily grey pubescent areas; dc setae presuturally white, postsuturally absent, acr setae absent, lateral scutal setae white, npl setae 0, spal setae 0, pal setae 0; proepisternum apubescent medially, grey pubescent laterally, long white setose; proepimeron grey pubescent, asetose; antepronotum antero-medially smooth (without any indentation); lateral postpronotum long white setose; postpronotal lobe yellow, grey pubescent, long white setose; scutellum grey pubescent, discal scutellar setae absent, apical scutellar setae absent; mesopostnotum grey pubescent, asetose; anatergite grey pubescent, asetose; katatergite apubescent, long white setose, elevated and smoothly convex; anepisternum grey pubescent dorsally, apubescent ventrally, anteriorly asetose, posteriorly short white setose, otherwise asetose; katepisternum apubescent, asetose; anepimeron apubescent, asetose; katepimeron apubescent, asetose; meron grey pubescent dorsally, apubescent ventrally, asetose; metakatepisternum large; metanepisternum grey pubescent, asetose; metepimeron yellow (same color as T1), white pubescent, long white setose, ± flat, infra-halter sclerite absent.

Legs : yellow to brown, setation comprised of white setae and brown macrosetae; pro coxa apubescent, short white setose; mes coxa apubescent, long white setose; met coxa laterally unsclerotized (membrane between coxa and metakatepisternum clearly visible), apubescent, long white setose; met trochanter sparsely setose medially; pro + mes femur yellow anteriorly, posteriorly brown, met femur yellow anteriorly, posteriorly brown, distinctly clubbed for nearly entire length, macrosetose with thickened spine-like macrosetae on protuberance in 2 antero-ventral and 2 postero-ventral rows, postero-ventrally sparse, short white setose; pro tibia straight; mes tibia straight; met tibia laterally arched, met tibia cylindrical with distinct ventral keel terminating into distinct spur, spur almost reaching tip of 1^st tarsomere, postero-laterally short white, appressed setose; pro + mes tarsomere 1 approximately as long as individual tarsomeres 2, 3, or 4, met tarsomere 1 as long as individual tarsomeres 2, 3, or 4; pulvillus well-developed, as long as well-developed claw, and as wide as base of claw; setiform empodium absent.

Wing : length = 7.8–10.4 mm; hyaline throughout, slightly brown stained along veins, veins light brown, microtrichia absent; cells r₁, r₄, m₃, + cua closed, r₅ open; C terminating at junction with M₁ (or M₁+M₂); Sc long, terminating in C proximal to r-m; R₄ terminates in R₁; R₅ terminates in R₁; auxiliary vein (R₃) at base of R₄ absent; R₄ and R₅ widest apart medially; r-m indistinct, R₄₊₅ and M₁ fused, forming an X; M₁ curves slightly anteriorly at r-m, M₁ (or M₁+M₂) terminates in C; base of M₃+M₄ present, M₃+M₄ not terminating together in C (not reaching wing margin), M₄ and CuA split proximally to m-cu (cell m₃ narrow proximally); CuP straight, cell cup wide, CuP and wing margin further apart proximally than distally; alula well-developed; halter light yellow, pubescent, dorsally asetose, ventrally yellow setose.

Abdomen : light brown to brown, setation comprised of scattered short white setae, T2–4 parallel-sided and not constricted waist-like, T surface entirely smooth; T1 yellow, T2–7 brown (sometimes medially light brown) with yellow posterior margins; T apubescent; T1 long white setose, T2–7 sparsely short white setose; S1 yellow, S2–7 light brown to brown with yellow posterior margins; S apubescent; S1 and S7 short white setose, S2–6 asetose; bullae on T2 absent.

♀ abdomen and genitalia: densely arranged anteriorly directed setae present on T7–8 and S8, only few on S7; T8 anterior apodeme present, broad and rectangular, auxiliary spiracle present; T9 formed by wide, rectangular sclerite with median protuberance; T9+10 entirely fused (sclerites indistinguishable), T10 divided into 2 heavily sclerotized acanthophorite plates; 6–8 acanthophorite spines per plate; 2 spermathecae, all equally large, not differentiated from spermathecal ducts, unsclerotized; individual spermathecal duct long; S9 (furca) formed by 1 sclerite, ring-like (joined anteriorly and posteriorly), anterior furcal apodeme present, 2 lateral projections forming divided apodeme, lateral furcal apodeme absent, median furcal bridge absent.

Male. Head: black, facial gibbosity yellow to light brown, in general densely white pubescent, white setose, regular, cylindrical setae; width distinctly greater than thorax (at postpronotal lobe), interocular distance on vertex larger than at ventral eye margin; vertex between compound eyes ± horizontally straight, medially only slightly below dorsal eye margin, vertex medially apubescent, laterally white pubescent, white setose; ocellar triangle apubescent; facial gibbosity distinct, well-developed and discernible in lateral view, mystax covering entire facial gibbosity, white; parafacial area less than ½ width of central facial gibbosity (at same level); frons not elevated, medially apubescent, laterally white pubescent, medially asetose, latero-ventrally white; occiput grey pubescent, white setose, median occipital sclerite brown macrosetose; pocl macrosetae absent; postgena sparsely grey pubescent, long, sparsely white setose; clypeus comprised of single sclerite, entirely sclerotized medially, recessed (concave), ventrally simple, posterior to proboscis, laterally connected to face by membranous cuticle; proboscis long, reaching fronto–clypeal suture, brown; labellum large, much wider than prementum, as long as prementum, unsclerotized laterally; maxillary palpus laterally compressed, bilobed apically, light brown, approximately ⅓ length of proboscis.

Antenna : brown; scape white setose dorsally, asetose ventrally; pedicel white setose dorsally and ventrally; postpedicel cylindrical in proximal ½, symmetrically bulbous in distal ½, ≥ 4.0 times as long as combined length of scape and pedicel, asetose; apical seta-like sensory element situated apically in cavity on postpedicel.

Thorax : dark brown, predominantly grey pubescent; scutum uniformly black, surface microrugose (slightly rugose ‘imitating’ pubescence), grey pubescent except for brown pubescent broad median stripe (not reaching posterior margin) and sublateral stripes (interrupted by transverse suture), scutal setation comprised of short white setae in primarily grey pubescent areas; dc setae presuturally white, postsuturally absent, acr setae absent, lateral scutal setae white, npl setae 0, spal setae 0, pal setae 0; proepisternum apubescent medially, grey pubescent laterally, long white setose; proepimeron grey pubescent, asetose; antepronotum antero-medially smooth (without any indentation); lateral postpronotum long white setose; postpronotal lobe yellow, grey pubescent, long white setose; scutellum grey pubescent, discal scutellar setae absent, apical scutellar setae absent; mesopostnotum grey pubescent, asetose; anatergite grey pubescent, asetose; katatergite apubescent, long white setose, elevated and smoothly convex; anepisternum grey pubescent dorsally, apubescent ventrally, anteriorly asetose, posteriorly short white setose, otherwise asetose; katepisternum apubescent, asetose; anepimeron apubescent, long white setose ventrally; katepimeron apubescent, asetose; meron grey pubescent, median stripe apubescent, asetose; metakatepisternum large; metanepisternum grey pubescent, asetose; metepimeron yellow (same color as T1), white pubescent, long white setose, ± flat, infra-halter sclerite absent.

Legs : yellow to brown, setation comprised of white setae and black macrosetae; pro coxa apubescent, short white setose; mes coxa apubescent, long white setose; met coxa laterally unsclerotized (membrane between coxa and metakatepisternum clearly visible), apubescent, long white setose; met trochanter sparsely setose medially; pro + mes femur yellow anteriorly, posteriorly brown, met femur yellow anteriorly, posteriorly brown, distinctly clubbed for nearly entire length, macrosetose with thickened spine-like macrosetae on protuberance in 2 antero-ventral and 2 postero-ventral rows, postero-ventrally sparse, long white erect setose; pro tibia straight; mes tibia straight; met tibia laterally arched, met tibia cylindrical with distinct ventral keel terminating into distinct spur, spur almost reaching tip of 1^st tarsomere, postero-laterally short white, appressed setose; pro + mes tarsomere 1 approximately as long as individual tarsomeres 2, 3, or 4, met tarsomere 1 as long as individual tarsomeres 2, 3, or 4; pulvillus well-developed, as long as well-developed claw, and as wide as the base of the claw; setiform empodium absent.

Wing : length = 7.1–7.6 mm; hyaline throughout, slightly brown stained along veins, veins brown, microtrichia absent; cells r₁, r₄, m₃, + cua closed, r₅ open; C terminating at junction with M₁ (or M₁+M₂); Sc long, terminating in C proximal to r-m; R₄ terminates in R₁; R₅ terminates in R₁; auxiliary vein (R₃) at base of R₄ absent; R₄ and R₅ widest apart medially; r-m indistinct, R₄₊₅ and M₁ fused, forming an X, rarely distinct, R₄₊₅ and M₁ apart, connected by crossvein; M₁ curves slightly anteriorly at r-m, M₁ (or M₁+M₂) terminates in C; base of M₃+M₄ present, M₃+M₄ not terminating together in C (not reaching wing margin), M₄ and CuA split proximally to m-cu (cell m₃ narrow proximally); CuP straight, cell cup wide, CuP and wing margin further apart proximally than distally; alula well-developed; halter light yellow, pubescent, dorsally asetose, ventrally yellow setose.

Abdomen : yellow to brown, setation comprised of scattered short white setae, T2–4 parallel-sided and not constricted waist-like, T surface entirely smooth; T1–7 yellow to orange, T2–7 antero-laterally brown; T apubescent; T1 and anterior ¼ of T2 long white setose, remaining T2 and T3–T7 sparsely white setose laterally; S1–7 yellow, brown medially; S predominantly apubescent; S1–7 sparsely short white setose; bullae on T2 transversely elongate, long (almost occupying entire lateral aspect of tergite), light brown, surface entirely smooth, T2 surface anterior to bullae smooth.

♂ abdomen and terminalia: T1–7 well-developed, entirely sclerotized, T8 postero-medially weakly sclerotized, with anterior transverse sclerotized bridge connecting lateral sclerites; T7–8 anteriorly with 2 lateral apodemes; T8 auxiliary spiracle present; S6 regular, without any special setation postero-medially; S8 simple plate, entire (undivided) ventro-medially, not fused to T8 dorso-laterally; epandrium formed by 2 sclerites, separated disto-medially and fused antero-medially, distally in dorsal view blunt with short, strong macrosetae at tip; subepandrial sclerite without lateral or median protuberances; hypandrium concave, cup-shaped, entirely sclerotized ventrally, entirely fused with gonocoxite, forming a gonocoxite-hypandrial complex, supra-hypandrial sclerite absent; gonocoxite simple, long, slightly curved dorsally, with median protuberance, gonocoxal apodeme absent; 2 functional phallic prongs, short and wide, medio-distally connected, parallel or diverging laterally, distally straight or only diverging slightly laterally; phallic epimere absent; lateral ejaculatory process absent; ejaculatory apodeme formed by single dorso-ventrally oriented plate; ventro-median margin of parameral sheath heavily sclerotized (appearing entirely closed); parameral sheath long, sperm sac entirely covered; sperm sac appearing ± heavily sclerotized.

Zimbabwe: Bulawayo: Bulawayo (20°09'00"S, 028°35'00"E, -20.15, 28.58333).

Botswana: Central: 1♂ Serowe, Farmers Brigade, 22°09'58"S, 026°43'31"E, 1990-04-00, Malaise trap, Forchhammer, P. (AAM-000809, NMSA); 4♂ Serowe, Farmers Brigade, 22°09'58"S, 026°43'31"E, 1987-04-00, Malaise trap, Forchhammer, P. (USNMENT00832025, USNMENT00832027, USNMENT00832028, USNMENT00891896, USNM); 1♀ Serowe, Farmers Brigade, 22°09'58"S, 026°43'31"E, 1987-04-00, Malaise trap, Forchhammer, P. (USNMENT00832026, USNM); Kgatleng: 2♀ Mochudi, 24°25'00"S, 026°08'00"E, 1982-04-19–1982-04-21, Louw, S. (BMSA(D)00087, BMSA(D)00091, BMSA); 4♂ Mochudi, 24°25'00"S, 026°08'00"E, 1982-04-19–1982-04-21, Louw, S. (BMSA(D)00088, BMSA(D)00089, BMSA(D)00090, BMSA(D)00092, BMSA); Mozambique: Gaza: 1♀ Mapai, 22°51'08"S, 031°58'02"E, 1951-05-00, Zumpt, F. (NMSA-DIP-044922, NMSA); Manica: 2♂ Zambéze amont de Tambara (= Nhacolo) Njanassé, Lac Msica, 16°38'21"S, 034°07'28"E, 1929-00-00, Lesne, P. (AAM-001199, AAM-001200, MNHN); 1♂ Inhacoro (= Nhacolo), 16°42'57"S, 034°15'10"E, 1928-05-00, Lesne, P. (Paratype Heleomydas lesnei, MNHN); Sofala: 1♂ Nova Chupanga, 17°07'32"S, 034°51'34"E, 0000-05-00, Lesne, P. (Holotype Heleomydas lesnei, MNHN); Namibia: Hardap: 2♂ Rehoboth, 9 km S, 23°23'28"S, 017°06'23"E, 1990-03-16, Pulawski, W. (CASENT8380010, CASENT8380011, CAS); 1♂ Rehoboth, 9 km S, 23°23'59"S, 017°04'12"E, 1990-03-16, Schwarz, M. (AAM-000872, Coll. Hauser); Khomas: 2♂ Seeis, 9 km ESE, 20°28'00"S, 017°38'00"E, 1976-03-12, Rozen, J. (AAM-000097, AAM-000098, AMNH); 1♂ Seeis, 22 km ESE, 20°31'00"S, 017°45'00"E, 1976-03-14, Rozen, J. (AAM-000099, AMNH); 1♀ Seeis, 22 km ESE, 20°31'00"S, 017°45'00"E, 1976-03-14, Rozen, J. (AAM-000100, AMNH); 2♀ Windhoek, 26 km N Road 1/6, 22°20'00"S, 017°04'00"E, 1984-03-29, dry stream bed Acacia riparian woodland, Londt, J., Stuckenberg, B. (NMSA-DIP-77046, NMSA-DIP-77050, NMSA); 1♂ Windhoek, 26 km N Road 1/6, 22°20'00"S, 017°04'00"E, 1984-03-29, dry stream bed Acacia riparian woodland, Londt, J., Stuckenberg, B. (NMSA-DIP-77047, NMSA); 1♀ Windhoek, 36 km E Road 6/1, 22°30'00"S, 017°22'00"E, 1984-03-17, dry river bed Acacia savanna / grassland, Londt, J., Stuckenberg, B. (NMSA-DIP-77048, NMSA); 1♂ Windhoek, 36 km E Road 6/1, 22°30'00"S, 017°22'00"E, 1984-03-17, dry river bed Acacia savanna / grassland, Londt, J., Stuckenberg, B. (NMSA-DIP-77049, NMSA); 1♂ Gamsberg, E of pass, 23°20'00"S, 016°20'00"E, 1999-03-12, Gess, F., Gess, S. (AAM-000203, AMGS); Omaheke: 2♀ Witvlei, 22°24'35"S, 018°29'30"E, 1970-03-01, Ross, E. (CASENT8380006, CASENT8380007, CAS); 1♂ Witvlei, 22°24'35"S, 018°29'30"E, 1970-03-01, Ross, E. (CASENT8380008, CASENT8380009, CAS); Otjozondjupa: 1♂ Gross Barmen Resort, 22°06'42"S, 016°44'48"E, 1992-03-19, at night, O’Brian, C., O’Brian, L., Marshall, G. (AAM-009904, CSCA); Zimbabwe: Bulawayo: 1♀ Bulawayo, 20°09'00"S, 028°35'00"E, 1917-05-00, Tucker, R. (SAM-DIP-A007141, Holotype, SAMC); Zimbabwe: 1♂ Worlds View, 18°09'49"S, 032°46'29"E, 1925-04-24, Stevenson, R. (NMSA-DIP-044922, NMSA); 1♂ Bazely Bridge, 19°15'01"S, 032°29'23"E, 1965-04-20, Cookson, D. (NMSA-DIP-031720, NMSA); Matabeleland North: 1♀ Khami Ruins, 20°09'30"S, 028°22'36"E, 1924-04-19, Rhodesia Museum (AAM-000647, NHMUK); 1♂ Khami Ruins, 20°09'30"S, 028°22'36"E, 1924-04-19, Rhodesia Museum (AAM-000648, NHMUK); 1♂ Khami, 20°09'30"S, 028°22'36"E, 1927-04-17, Rhodesia Museum (AAM-009508, NHMW); 1♀ Khami Ruins, 20°09'30"S, 028°22'36"E, 1924-04-19, Rhodesia Museum (NMZ1701, NMBZ); 1♂ Khami, 20°09'30"S, 028°22'36"E, 1927-04-17, Rhodesia Museum (NMZ1707, NMBZ); Matabeleland South: 1♀ Matopos, 20°23'02"S, 028°30'28"E, 1920-05-02, Rhodesia Museum (Holotype Rhopalia flavomarginata, BMNH(E)241675, NHMUK); 1♂ Matopos, 20°23'02"S, 028°30'28"E, 1925-04-22, Stevenson, R. (NMSA-DIP-044921, NMSA); 3♀ 6♂ Matopos Hills, 20°26'39"S, 028°30'58"E, 1932-04-00, Ogilvie, L. (AAM-000652–AAM-000660, NHMUK); 1♂ Matopos Hills, 20°26'39"S, 028°30'58"E, 1932-04-00, Ogilvie, L. (AAM-003022, RBINS); 1?* Balla-Balla (= Mbalabala), 20°26'60"S, 029°02'09"E, no date, along sandy path in Mopane forest (AAM-000072, RBINS); 1♀ Balla-Balla (= Mbalabala), 20°26'60"S, 029°02'09"E, 1933-03-00, Cuthbertson, A. (AAM-001357, RBINS); 1♀ 2♂ Balla-Balla (= Mbalabala), 20°26'60"S, 029°02'09"E, 1933-02-00, Cuthbertson, A. (AAM-000095–AAM-000096, AMNH); 1♀ Ori River, Matopos, 20°33'26"S, 028°30'49"E, 1930-05-01, Stevenson, R. (NMZ1709, NMBZ); 3♂ Beit Bridge, 22°12'51"S, 029°59'29"E, 1932-04-00, Ogilvie, L. (AAM-000071, AAM-000649, AAM-000650, NHMUK); 1♀ Beit Bridge, 22°12'51"S, 029°59'29"E, 1932-04-00, Ogilvie, L. (AAM-008033, NHMUK); 1♀ Beit Bridge, 22°12'51"S, 029°59'29"E, 1932-04-00, Ogilvie, J. (SDEI); Midlands: 1♂ Shangani, De Beer’s Ranch, 19°00'00"S, 028°54'00"E, 1932-05-00, Ogilvie, L. (AAM-000651, NHMUK).

See above for genus.

Dikow (2017) reported that the females of H. crassipes appear to lack bullae on the postero-lateral surface of abdominal tergite 2.

The genus can be delineated by the densely setose head, the distinctly and deeply rugose scutum, and the costal vein terminating where M₁ joins the wing margin.

Known only from three disjunct localities in northern Namibia, north-eastern Botswana, and north-eastern Zimbabwe (Fig. 56). A rarely collected genus known only from four specimens in museum collections, three collecting events between 1930–1986 (Table 1), and one observation on iNaturalist in 2019 (https://www.inaturalist.org/observations/26760859). The genus is not known to occur in any biodiversity hotspot. Adult flies are active in mid to late winter (Table 2), which corresponds to the dry season and lower temperatures. Nothing is known of the biology.

The species is distinguished from congeners by the wide face and vertex (similar width), the entirely apubescent anepimeron, and the sparsely grey pubescent abdominal tergites.

Female. Head: brown, facial gibbosity yellow, in general white pubescent, white setose, regular, cylindrical setae; width distinctly greater than thorax (at postpronotal lobe), interocular distance on vertex larger than at ventral eye margin; vertex between compound eyes ± horizontally straight, medially only slightly below dorsal eye margin, vertex white pubescent, white setose; ocellar triangle apubescent; facial gibbosity distinct, well-developed and discernible in lateral view, mystax covering entire facial gibbosity, white; parafacial area approximately as wide as ¾ width of central gibbosity (at same level); frons not elevated, medially apubescent, laterally white pubescent, white setose; occiput grey pubescent, white setose, median occipital sclerite brown macrosetose; pocl macrosetae absent; postgena sparsely grey pubescent, long, sparsely white setose; clypeus comprised of single sclerite, entirely sclerotized medially, recessed (concave), ventrally simple, posterior to proboscis, laterally connected to face by membranous cuticle; proboscis short, nob-like, occupying approximately ⅓ length of oral cavity, light brown; labellum small, as wide as prementum, as long as prementum, unsclerotized laterally; maxillary palpus laterally compressed (triangular), light brown, approximately ½ length of proboscis.

Antenna : brown; scape white setose dorsally, asetose ventrally; pedicel light brown setose dorsally and ventrally; postpedicel cylindrical in proximal ½, symmetrically bulbous in distal ½, ≥ 2.0 times as long as combined length of scape and pedicel, asetose; apical seta-like sensory element situated apically in cavity on postpedicel.

Thorax : black or light brown to black, predominantly white pubescent; scutum black, light brown stripes medially and laterally, surface macrorugose (distinctly and deeply rugose), predominantly apubescent, paramedian stripes (merging on posterior margin) and lateral margins grey pubescent, scutal setation comprised of long white setae in pubescent areas; dc setae pre- and postsuturally white, acr setae absent, lateral scutal setae white, npl setae 0, spal setae 0, pal setae 0; proepisternum apubescent medially, grey pubescent laterally, long white setose; proepimeron grey pubescent, asetose; antepronotum antero-medially smooth (without any indentation); lateral postpronotum long white setose; postpronotal lobe yellow, white pubescent, long white setose; scutellum grey pubescent, discal scutellar setae absent, apical scutellar setae absent; mesopostnotum grey pubescent, asetose; anatergite grey pubescent, asetose; katatergite apubescent, long white setose, elevated and smoothly convex; anepisternum white pubescent, anteriorly asetose, posteriorly 1–2 white setae postero-ventrally, otherwise asetose; katepisternum white pubescent dorsally, apubescent ventrally, asetose; anepimeron white pubescent, posterior ½ apubescent, asetose; katepimeron white pubescent, asetose; meron white pubescent, median stripe apubescent, asetose; metakatepisternum large; metanepisternum white pubescent, asetose; metepimeron yellow (same color as T1), white pubescent, long white setose, ± flat, infra-halter sclerite absent.

Legs : light brown to brown, setation comprised of white setae and brown macrosetae; pro coxa sparsely grey pubescent, long white setose; mes coxa sparsely grey pubescent, long white setose; met coxa laterally unsclerotized (membrane between coxa and metakatepisternum clearly visible), sparsely grey pubescent, long white setose; met trochanter setose medially; pro + mes femur light brown to brown, met femur light brown to brown, evenly clubbed in distal ¾, macrosetose, 1 antero-ventral and 1 postero-ventral row of macrosetae, postero-ventrally long white, erect setose with setae arranged in distinct row; pro tibia laterally arched; mes tibia laterally arched; met tibia laterally arched, met tibia cylindrical with distinct ventral keel terminating into distinct spur, postero-laterally sparse long white, erect setose with setae arranged in distinct row; pro + mes tarsomere 1 slightly longer than tarsomere 2, met tarsomere 1 slightly longer than tarsomere 2; pulvillus well-developed, as long as well-developed claw, and as wide as the base of the claw; setiform empodium absent.

Wing : length = 7.4 mm; hyaline throughout, veins light brown, microtrichia absent; cells r₁, r₄, m₃, + cua closed, r₅ open; C terminating at junction with M₁ (or M₁+M₂); Sc long, terminating in C proximal to r-m; R₄ terminates in R₁; R₅ terminates in R₁; auxiliary vein (R₃) at base of R₄ absent; R₄ and R₅ widest apart medially; r-m indistinct, R₄₊₅ and M₁ fused, forming an X; M₁ curves slightly anteriorly at r-m, M₁ (or M₁+M₂) terminates in C; base of M₃+M₄ present, M3+M₄ not terminating together in C (not reaching wing margin), M₄ and CuA split proximally to m-cu (cell m₃ narrow proximally); CuP straight, cell cup wide, CuP and wing margin further apart proximally than distally; alula well-developed; halter light brown, pubescent, dorsally asetose, ventrally yellow setose.

Abdomen : brown, setation comprised of scattered short white setae, T2–4 parallel-sided and not constricted waist-like, T surface entirely smooth; T1–3 brown with white posterior margin, T4–7 brown; T apubescent; T1 long white setose, T2–7 short white setose; S1–7 light brown; S apubescent; S1–7 sparsely short yellow setose; bullae on T2 transversely elongate, brown, surface entirely smooth, T2 surface anterior to bullae smooth.

♀ abdomen and genitalia: densely arranged anteriorly directed setae present on T7–8 and S7–8; T8 anterior apodeme indiscernible (not dissected), auxiliary spiracle indiscernible (not dissected); T9 formed by wide, rectangular sclerite with median protuberance; T9+10 entirely fused (sclerites indistinguishable), T10 divided into 2 heavily sclerotized acanthophorite plates; 5 acanthophorite spines per plate.

Male. Head: black, in general grey pubescent, light brown, regular, cylindrical setae; width distinctly greater than thorax (at postpronotal lobe), interocular distance on vertex larger than at ventral eye margin; vertex between compound eyes ± horizontally straight, medially only slightly below dorsal eye margin, vertex grey pubescent, white setose; ocellar triangle apubescent; facial gibbosity distinct, well-developed and discernible in lateral view, mystax covering entire facial gibbosity, light brown, white ventrally; parafacial area approximately as wide as ¾ width of central gibbosity (at same level); frons not elevated, medially apubescent, laterally grey pubescent, dark brown; occiput grey pubescent, white setose, median occipital sclerite brown macrosetose; pocl macrosetae absent; postgena sparsely grey pubescent, long, sparsely light brown setose; clypeus comprised of single sclerite, entirely sclerotized medially, recessed (concave), ventrally simple, posterior to proboscis, laterally connected to face by membranous cuticle; proboscis short, nob-like, occupying approximately ⅓ length of oral cavity, brown; labellum small, as wide as prementum, as long as prementum, unsclerotized laterally; maxillary palpus laterally compressed (triangular), brown, approximately ½ length of proboscis.

Antenna : brown; scape white setose dorsally, asetose ventrally; pedicel light brown setose dorsally and ventrally; postpedicel cylindrical in proximal ½, symmetrically bulbous in distal ½, ≥ 3.0 times as long as combined length of scape and pedicel, asetose; apical seta-like sensory element situated apically in cavity on postpedicel.

Thorax : black or brown, predominantly grey pubescent; scutum uniformly black, surface macrorugose (distinctly and deeply rugose), predominantly apubescent, paramedian stripes (merging on posterior margin) and lateral margins grey pubescent, scutal setation comprised of long white to yellow setae in pubescent areas; dc setae pre- and postsuturally white, acr setae absent, lateral scutal setae white, npl setae 0, spal setae 0, pal setae 0; proepisternum apubescent medially, grey pubescent laterally, long white setose; proepimeron grey pubescent, asetose; antepronotum antero-medially smooth (without any indentation); lateral postpronotum long white setose; postpronotal lobe light brown, grey pubescent, long white setose; scutellum grey pubescent, discal scutellar setae absent, apical scutellar setae absent; mesopostnotum grey pubescent, asetose; anatergite grey pubescent, asetose; katatergite apubescent, long white setose, elevated and smoothly convex; anepisternum sparsely grey pubescent, anteriorly asetose, posteriorly asetose, otherwise asetose; katepisternum dorsally sparsely grey pubescent, asetose; anepimeron apubescent, asetose; katepimeron sparsely grey pubescent, asetose; meron apubescent, asetose; metakatepisternum large; metanepisternum grey pubescent, asetose; metepimeron brown (same color as T1), grey pubescent, long white setose, ± flat, infra-halter sclerite absent.

Legs : brown, setation comprised of white setae and brown macrosetae; pro coxa sparsely grey pubescent, long white setose; mes coxa sparsely grey pubescent, long white setose; met coxa laterally unsclerotized (membrane between coxa and metakatepisternum clearly visible), sparsely grey pubescent, long white setose; met trochanter setose medially; pro + mes femur brown, met femur brown, evenly clubbed in distal ¾, macrosetose, 1 antero-ventral and 1 postero-ventral row of macrosetae, postero-ventrally long white, erect setose with setae arranged in distinct row; pro tibia laterally arched; mes tibia laterally arched; met tibia laterally arched, met tibia cylindrical with distinct ventral keel terminating into distinct spur, postero-laterally sparse long white, erect setose with setae arranged in distinct row; pro + mes tarsomere 1 slightly longer than tarsomere 2, met tarsomere 1 slightly longer than tarsomere 2; pulvillus well-developed, as long as well-developed claw, and as wide as the base of the claw; setiform empodium absent.

Wing : length = 6.0 mm; hyaline throughout, veins light brown, microtrichia absent; cells r₁, r₄, m₃, + cua closed, r₅ open; C terminating at junction with M₁ (or M₁+M₂); Sc long, terminating in C proximal to r-m; R₄ terminates in R₁; R₅ terminates in R₁; auxiliary vein (R₃) at base of R₄ absent; R₄ and R₅ widest apart medially; r-m indistinct, R₄₊₅ and M₁ fused, forming an X; M₁ curves slightly anteriorly at r-m, M₁ (or M₁+M₂) terminates in C; base of M₃+M₄ present, M₃+M₄ not terminating together in C (not reaching wing margin), M₄ and CuA split proximally to m-cu (cell m₃ narrow proximally); CuP straight, cell cup wide, CuP and wing margin further apart proximally than distally; alula well-developed; halter light brown, pubescent, dorsally asetose, ventrally yellow setose.

Abdomen : brown, setation comprised of scattered short white setae, T2–4 parallel-sided and not constricted waist-like, T surface entirely smooth; T1 brown, T2–6 brown with white posterior margin, T7 brown; T sparsely grey pubescent; T1–2 long white setose, T3–7 short white setose; S1–6 light brown, S7 brown; S1–3 apubescent, S4–7 sparsely grey pubescent; S1–7 short white setose; bullae on T2 transversely elongate, light brown, surface entirely smooth, T2 surface anterior to bullae smooth.

♂ abdomen and terminalia: not dissected.

Botswana: Chobe: Kabulabula, Chobe river (17°48'41"S, 024°56'48"E, -17.81139, 24.94667).

Botswana: Chobe: 1♂ Kabulabula, Chobe river, 17°48'41"S, 024°56'48"E, 1930-07-11–1930-07-24, Vernay-Lang Kalahari Expedition (NMSA-DIP-43314, Holotype, NMSA); 1♀ Kabulabula, Chobe river, 17°48'41"S, 024°56'48"E, 1930-07-11–1930-07-24, Vernay-Lang Kalahari Expedition (NMSA-DIP-57787, Paratype, NMSA); Namibia: Ohangwena: 1♂ Oshikango, 17°24'00"S, 015°53'00"E, 1948-07-00, Koch, C. (NMSA-DIP-43304, Holotype Lachnocorynus kochi, NMSA).

Botswana: Ngamiland: 18°57'56"S, 22°56'32"E, 2019-06-10, Taylor, R. (record URL www.inaturalist.org/observations/26760859).

Known only from three localities in northern Botswana and north-central Namibia (Fig. 56). A rarely collected species known only from three specimens and two collecting events in 1930 and 1948 and one observation in 2019 (Table 1). The species is not known to occur in any currently recognized biodiversity hotspot. Adult flies are active in June–July in mid winter (Table 2), which corresponds to the dry season and lower temperatures (data for Kasane, Botswana, see https://worldweather.wmo.int/en/city.html?cityId=1545 and Oshikango, Namibia, see https://www.worldweatheronline.com/oshikango-weather-averages/ohangwena/na.aspx). Nothing is known of the biology.

The male holotype of L. kochi is not well-preserved (Figs 47–49) and it cannot in any meaningful way be distinguished from L. chobeensis. The only differences of the male holotypes pertain to the abdominal colouration (T1 and T7 entirely brown in L. chobeensis and all tergites with yellow posterior margins in L. kochi). The male terminalia were not dissected but are morphologically very similar based on the externally visible structures. These minute differences in colouration cannot be utilized to delineate species and we, therefore, synonymize the two species. Both species were described by Hesse (1969) and he designated L. chobeensis as the type species of the genus. We, therefore, assign L. chobeensis as the senior synonym and this species has also been collected in both the female and male sex during the same collecting event.

The species is distinguished from congeners by the very narrow face (vertex much wider than face), the medially apubescent anepimeron (grey pubescent dorsally and ventrally), the apubescent katepimeron, and the apubescent abdominal tergites.

Greek steno = narrow, cephalos = head. The specific epithet refers to the very narrow ventral face of this species.

Female. unknown.

Male. Head: black, facial gibbosity brown, in general grey pubescent, white and light brown, regular, cylindrical setae; width distinctly greater than thorax (at postpronotal lobe), interocular distance on vertex distinctly larger than at ventral eye margin; vertex between compound eyes slightly depressed (less than 60° angle on median eye margin), vertex predominantly apubescent, only lateral margin grey pubescent, white setose; ocellar triangle apubescent; facial gibbosity distinct, well-developed and discernible in lateral view, mystax covering entire facial gibbosity, light brown, white ventrally; parafacial area approximately as wide as ½ width of central facial gibbosity (at same level); frons not elevated, medially apubescent, laterally grey pubescent, medially asetose, latero-ventrally brown; occiput grey pubescent, white setose, median occipital sclerite light brown macrosetose; pocl macrosetae absent; postgena sparsely grey pubescent, long, sparsely white setose; clypeus comprised of single sclerite, entirely sclerotized medially, recessed (concave), ventrally simple, posterior to proboscis, laterally connected to face by membranous cuticle; proboscis short, nob-like, occupying approximately ⅓ length of oral cavity, light brown; labellum small, as wide as prementum, as long as prementum, unsclerotized laterally; maxillary palpus cylindrical, light brown, longer than ½ length of proboscis.

Antenna : brown; scape asetose; pedicel white setose dorsally and ventrally; postpedicel indiscernible (broken).

Thorax : black, predominantly grey pubescent; scutum uniformly black, surface macrorugose (distinctly and deeply rugose), predominantly apubescent, paramedian stripes (merging on posterior margin) grey to light brown pubescent and lateral margins grey pubescent, scutal setation comprised of long white to yellow setae in pubescent areas; dc setae pre- and postsuturally white or yellow, acr setae absent, lateral scutal setae white, npl setae 0, spal setae 0, pal setae 0; proepisternum apubescent medially, grey pubescent laterally, long white setose; proepimeron grey pubescent, asetose; antepronotum antero-medially smooth (without any indentation); lateral postpronotum long white setose; postpronotal lobe yellow, grey pubescent, long white setose; scutellum sparsely grey pubescent, discal scutellar setae absent, apical scutellar setae absent; mesopostnotum partly grey pubescent, asetose; anatergite grey pubescent, asetose; katatergite apubescent, long white setose, slightly elevated, smoothly convex; anepisternum grey pubescent, anteriorly asetose, posteriorly asetose, otherwise asetose; katepisternum dorsally grey pubescent, ventrally apubescent, asetose; anepimeron dorsally and ventrally grey pubescent, median stripe apubescent, asetose; katepimeron apubescent, asetose; meron grey pubescent, median stripe apubescent or white pubescent, median stripe apubescent, asetose; metakatepisternum large; metanepisternum grey pubescent, asetose; metepimeron brown (same color as T1), sparsely grey pubescent, long white setose, ± flat, infra-halter sclerite absent.

Legs : yellow to brown, setation comprised of white setae and brown macrosetae; pro coxa sparsely grey pubescent, long white setose; mes coxa sparsely grey pubescent, long white setose; met coxa laterally unsclerotized (membrane between coxa and metakatepisternum clearly visible), sparsely grey pubescent, long white setose; met trochanter setose medially; pro + mes femur yellow, met femur brown, evenly clubbed in distal ¾, macrosetose, 1 antero-ventral and 1 postero-ventral row of macrosetae, 2 macrosetae anteriorly distally, postero-ventrally sparse, long white erect setose; pro tibia straight; mes tibia straight; met tibia laterally arched, met tibia cylindrical with distinct ventral keel terminating into distinct spur, postero-laterally short white, appressed setose; pro + mes tarsomere 1 approximately as long as individual tarsomeres 2, 3, or 4, met tarsomere 1 as long as individual tarsomeres 2, 3, or 4; pulvillus well-developed on pro and mes legs, smaller on met legs; setiform empodium absent.

Wing : length = 5.7 mm; hyaline throughout, veins yellow, microtrichia absent; cells r₁, r₄, m_3, + cua closed, r₅ open; C terminating at junction with M₁ (or M₁+M₂); Sc long, terminating in C proximal to r-m; R₄ terminates in R₁; R₅ terminates in R₁; auxiliary vein (R₃) at base of R₄ absent; R₄ and R₅ widest apart medially; r-m distinct, R₄₊₅ and M₁ apart, connected by crossvein; M₁ curves slightly anteriorly at r-m, M₁ (or M₁+M₂) terminates in C; base of M₃+M₄ present, M₃+M₄ not terminating together in C (not reaching wing margin), M₄ and CuA split proximally to m-cu (cell m₃ narrow proximally); CuP straight, cell cup wide, CuP and wing margin further apart proximally than distally; alula well-developed; halter light yellow, pubescent, asetose.

Abdomen : brown, setation comprised of scattered short white setae, T2–4 parallel-sided and not constricted waist-like, T surface entirely smooth; T1–7 dark brown dorsally, brown laterally, posterior margins yellowish; T apubescent; T1–2 long white setose, T3–7 short white setose; S1–5 yellow with white posterior margins, S6–8 light brown; S apubescent; S1 asetose, S2–7 sparsely white setose; bullae on T2 transversely elongate, light brown, surface entirely smooth, T2 surface anterior to bullae smooth.

♂ abdomen and terminalia: T1–7 well-developed, entirely sclerotized, T8 postero-medially weakly sclerotized, with anterior transverse sclerotized bridge connecting lateral sclerites. ♂ terminalia not dissected.

Zimbabwe: Mashonaland East: Kotwa, Chimana Causeway (17°06'00"S, 032°38'00"E, -17.1, 32.63333).

Zimbabwe: Mashonaland East: 1♂ Kotwa, Chimana Causeway, 17°06'00"S, 032°38'00"E, 1986-08-05, Lillig, M., Potel, S. (AAM-003060, Holotype, SNSB-ZSM).

Known only from the type locality in north-eastern Zimbabwe (Fig. 56). A rarely collected species known only from a single specimen and collecting event in 1986 (Table 1). The species is not known to occur in any currently recognized biodiversity hotspot. Adult flies are active in late winter (Table 2), which corresponds to the dry season and lower temperatures (data for Mount Darwin, Zimbabwe, see https://worldweather.wmo.int/en/city.html?cityId=956). Nothing is known of the biology.