Research Article |
Corresponding author: Bradley J. Sinclair ( bradley.sinclair@inspection.gc.ca ) Academic editor: Torsten Dikow
© 2019 Bradley J. Sinclair.
This is an open access article distributed under the terms of the CC0 Public Domain Dedication.
Citation:
Sinclair BJ (2019) Revision of the southern African genus Stuckenbergomyia Smith, 1971 (Diptera, Empidoidea) and proposal of a new subfamily. African Invertebrates 60(1): 133-145. https://doi.org/10.3897/afrinvertebr.60.35556
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The genus Stuckenbergomyia Smith is revised with the description of a new species from Namibia (S. namibiensis sp. nov.) and an undescribed species based on females from Western Cape Province of South Africa. The genus is fully illustrated and its phylogenetic relationships within the Hybotidae are discussed with the proposal of a new subfamily, Stuckenbergomyiinae subfam. nov.
Mozambique, Namibia, South Africa, Brandberg, new species, new subfamily
The genus Stuckenbergomyia Smith, 1971 is an odd genus of the family Hybotidae (Diptera, Empidoidea), characterised by a short spur vein arising from or near cell cua (anterior cubital). The genus is endemic to southern Africa, recorded from Mozambique, South Africa, Zimbabwe and now Namibia. Originally assigned to the Ocydromiinae, the genus is currently placed as incertae sedis in the Hybotidae (
Aside from two species of Ocydromia Meigen, 1820 (Ocydromiinae) recorded from East Africa and South Africa, Stuckenbergomyia is the only other Afrotropical genus of Hybotidae not assigned to the subfamilies Tachydromiinae and Hybotinae (
This study is based on material loaned from or deposited in the following institutions: Canadian National Collection of Insects, Ottawa, Canada (
Terminology used for adult structures follows those of
Stuckenbergia Smith, 1969: 125 [preoccupied by Stuckenbergia Tchernychev, 1898: 24 (fossil Porifera)]. Type species: Stuckenbergia tumbinensis Smith (original designation).
Stuckenbergomyia
Smith, 1971: 699. Replacement name for Stuckenbergia Tchernychev. Other references:
The genus (as in Figs
Head
: Holoptic with enlarged facets on upper two-thirds or dichoptic (facets not enlarged); eyes bare (ommatrichia absent). Face nearly completely membranous, U-shaped to base of antennal sockets. Ocellar triangle elevated in holoptic species; pair of ocellar setae very short, indistinguishable from other setae on triangle. Antenna inserted at middle of eye height; scape and pedicel subequal in length; scape bare, pedicel with circlet of subapical setulae; postpedicel elongate, tapered, 2–3× length of scape and pedicel combined; two-articled stylus, with short, apical peg-like receptor. Proboscis (as in Fig.
Thorax : Moderately to strongly arched. Acrostichals biserial or 4-serial; dorsocentral setae uniserial and better developed posteriorly; numerous postpronotal and notopleural setae; 1 postalar seta; 2 or more pairs of marginal scutellar setae. Prosternum separate; laterotergite bare.
Legs
: Lacking modified setae and processes; base of fore tibia with posteroventral gland (Fig.
Wing
(Length 2.5–3.2 mm) (as in Fig.
Abdomen : Sclerites well developed, bearing scattered slender setae; tergite 8 slender medially, strap-like, symmetrical. Segment 8 rotated nearly 45° to right.
Male terminalia : Symmetrical, rotated 45° to right; held apically, upright or arched anteriorly over abdomen. Cercus thinly sclerotised, weakly pigmented, clothed in slender setae; hypoproct broad with fine setae on posterior margin. Epandrial lamellae narrowly joined; surstylus undifferentiated, subapical or broadly articulated. Hypandrium trough-shaped, without apical lobes; postgonite sickle-shaped, slender, closely associated with phallus; ventral apodeme broad, plate-like. Ejaculatory apodeme elongate, narrow. Phallus mostly membranous, with expanded apex.
Similar to male, dichoptic, eye facets not enlarged. Apex of abdomen somewhat truncate with segment 8 partially retracted into segment 7. Female terminalia (based on S. namibiensis) (Figs
Described species of Stuckenbergomyia are recorded from Mozambique, Namibia and South Africa. An undescribed female (in Natural History Museum, London), representing an additional species, is recorded from Zimbabwe (Fig.
Stuckenbergomyia can be identified by using the key to genera in
Specimens have only been collected by Malaise traps, yellow pans and light traps and there are no direct observations on habits. Adult mouthpart morphology (i.e. angle of proboscis; absence of epipharyngeal blades) and the observation of pollen grains in the dissected male and female abdomens of S. namibiensis, provides evidence that Stuckenbergomyia visits flowers and feeds on pollen.
The specific epithet refers to the country of origin, Namibia.
This species is characterised by the pair of dark vittae between acrostichals and dorsocentrals; broad wings, yellow legs and 5–7 pairs of long scutellar setae; male terminalia: nearly symmetrical, held at apex of abdomen, surstyli not clearly differentiated.
Head : Holoptic with enlarged facets on upper two-thirds. Antenna with scape and pedicel paler than dark brown postpedicel; postpedicel length less than 4× basal width; stylus cylindrical, shorter than basal width of postpedicel; apical mechanoreceptor one-third length of stylus.
Thorax : Mostly brown with grey pruinescence. Scutum with pair of dark vittae between acrostichals and dorsocentral rows (viewed anteriorly); anterior margin of postpronotal lobe shiny, lacking pruinescence. Acrostichals 4-serial anteriorly, biserial anterior to prescutellar depression; dorsocentral setae biserial and short anteriorly, longer and uniserial at prescutellar depression; postpronotal setae numerous, short and pale; numerous pale presutural and postsutural supra-alar setae; 3–4 short pale notopleural setae; 1 pale postalar seta; 5–7 pairs of pale scutellar setae, slightly longer than length of scutellum. Proepisternum with a few short, pale setae.
Legs : Yellow, including at least apical half of coxae; apical tarsomeres increasingly darker.
Wing (2.5–3 mm): Broad, anal lobe nearly right-angled; alula well-developed. Costal margin at humeral crossvein expanded, costal cell broad; costa gradually reduced beyond R4+5; spur vein arising between cells bm and cua or from cell cua. Halter knob pale.
Abdomen : Dark brown, concolorous with thorax; setae pale; sternites paler than tergites; tergite 8 narrow medially, expanded laterally, bearing pair of setae.
Male terminalia
(Figs
Similar to male, except dichoptic; frons broad with thick grey pruinescence; abdomen truncate apically (Fig.
Stuckenbergomyia namibiensis sp. nov., male and female terminalia. 3 Male, lateral view 4 Male, dorsal view 5 Phallus, dorsal view 6 Female, lateral view 7 Spermatheca, dorsal view. Abbreviations: ej apod – ejaculatory apodeme, epand – epandrium, epiprct – epiproct, hypd – hypandrium, hyprct – hypoproct, pgt – postgonite, ph – phallus, tg – tergite, v apod – ventral apodeme. Scale bars: 0.1 mm.
NAMIBIA: Brandberg, Mason Shelter, 21°04'42"S 14°35'33"E (Fig.
Holotype ♂, labelled: “Namibia: BRANDBERG / Mason Shelter / 21°04'42"S 14°35'33"E / 05–14.iii.2002, 1750 m [elev.] / A.H. Kirk-Spriggs / light trap sample”; “HOLOTYPE / Stuckenbergomyia / namibiensis / Sinclair [red label]” (
Paratypes: NAMIBIA: 1♂, 1♀, same data as holotype (
This species was not included in the original list of Empidoidea from the Brandberg Massif (
Stuckenbergia secunda Smith, 1969: 128. Type locality: Pietermaritzburg, KwaZulu-Natal, South Africa.
Stuckenbergomyia secunda: Smith, 1980: 436 (catalogue).
This species is characterised by the faint brown vittae beneath acrostichals and dorsocentrals; broad wings and 4 pairs of long scutellar setae; male terminalia: symmetrical, held at apex of abdomen, surstyli broadly articulated lobes.
Head : Holoptic with enlarged facets on upper two-thirds. Antenna dark brown; postpedicel length ca. 4× basal width; stylus cylindrical, about as long as basal width of postpedicel; apical mechanoreceptor one-third length of stylus.
Thorax : Mostly dark greyish pruinescence. Scutum with brownish vittae below acrostichals and dorsocentral rows (viewed anteriorly); anterior margin of postpronotal lobe shiny, lacking pruinescence. Acrostichals 4-serial anteriorly, biserial anterior to prescutellar depression; dorsocentral setae biserial and short anteriorly, longer, darker and uniserial at prescutellar depression; postpronotal setae numerous, long and pale; numerous pale presutural and postsutural supra-alar setae; 4 pale notopleural setae; 1 pale postalar seta; 4 pairs of pale scutellar setae, longer than length of scutellum. Proepisternum with several long, pale setae.
Legs
: Mostly brown, with apex of femora and base of tibiae yellowish (Fig.
Wing
(2.7–3 mm) (Fig.
Abdomen : Slightly paler than thorax; setae pale; sternites paler than tergites; tergite 8 narrow medially, expanded laterally, bearing pair of setae.
Male terminalia
(Figs
Stuckenbergomyia secunda (Smith). 8 Holotype labels (upper label is reverse side of second label) 9 Holotype habitus, lateral view 10 Male habitus, Louwsberg specimen 11 Wing 12 Male foreleg, arrow pointing to fore tibial gland, posterior view. Abbreviations: cua – anterior cubital cell, CuA+CuP – anterior branch of cubital vein + posterior branch of cubital vein, dm – discal medial cell, M1 – first branch of media, M2 – second branch of media, M4 – fourth branch of media, Sc – subcostal vein. Scale bars: 1.0 mm (8–11); 0.5 (12).
Unknown.
SOUTH AFRICA, Pietermaritzburg [29°36'S, 30°22'E] (Fig.
Holotype ♂, labelled (Fig.
SOUTH AFRICA: 2♂ [
Stuckenbergia tumbinensis Smith, 1969: 126. Type locality: Tumbine Mountains, Mozambique.
Stuckenbergomyia tumbinensis: Smith, 1980: 436 (catalogue).
This species is characterised by the biserial acrostichals and uniserial dorsocentral setae; narrow wings with undeveloped alula and 2 pairs of long scutellar setae; male terminalia: very large, symmetrical, held erect over right side of abdomen.
Head : Dichoptic with facets not enlarged. Antenna with scape and pedicel paler than dark brown postpedicel; postpedicel length slightly longer than 4× basal width; stylus cylindrical, about as long as basal width of postpedicel; apical mechanoreceptor one-half length of stylus.
Thorax : Mostly dark with thin greyish pruinescence. Scutum with narrow brownish vittae between acrostichals and dorsocentral rows (viewed posteriorly). Acrostichals biserial; dorsocentral setae uniserial, longer, darker posteriorly; postpronotal setae numerous, long and pale; numerous pale presutural and postsutural supra-alar setae; 3 pale notopleural setae; 1 pale postalar seta; 2 pairs of pale scutellar setae, longer than length of scutellum. Proepisternum with several long, pale setae.
Legs
: Yellowish-brown; femora darkened about middle; tibia and tarsi darker; basal half of tarsomere 1 yellowish (Fig.
Wing (3–3.2 mm): Narrow, anal lobe obtuse, not sharply angled; alula undeveloped. Costal margin at humeral crossvein not expanded; costa gradually reduced beyond M1; spur vein arising from between cells bm and cua. Halter knob pale.
Abdomen : Dark brown, concolorous with thorax; setae pale; tergite 8 narrow medially, expanded laterally, bearing 3 setae.
Male terminalia
(Figs
Stuckenbergomyia species, male terminalia. 13 S. secunda (Smith), lateral view 14 S. secunda, dorsal view 15 S. tumbinensis (Smith), epandrium and proctiger, dorsal view 16 S. tumbinensis, phallus, dorsal view. Abbreviations: ej apod – ejaculatory apodeme, hypd – hypandrium, hyprct – hypoproct, pgt – postgonite, sur – surstylus, v apod – ventral apodeme. Scale bars: 0.1 mm.
Unknown.
Mozambique: Zambezia Province, Milange, Tumbine Mountain [16°2'36"S, 36°47'41"E] (Fig.
Holotype ♂, labelled (Fig.
Paratypes: MOZAMBIQUE: 2♂, same data as holotype,
Stuckenbergomyia species. 17 S. tumbinensis (Smith), holotype habitus, lateral view 18 Holotype labels 19 S. secunda (Smith), mouthparts, arrow pointing to palpifer. Abbreviations: hyphar – hypopharynx, lbl – labellum, lbr – labrum, premnt – prementum. Scale bars: 1.0 mm (17); 0.5 mm (19).
This species is characterised by a narrow pair of vittae between acrostichals and dorsocentrals and broader brown vittae along supra-alars; broad wings and 7 pairs of whitish scutellar setae.
Head : Dichoptic without enlarged facets. Frons parallel-sided with dense grey pruinescence; brownish stripe medially; ocellar triangle blacking. Antenna with scape and pedicel paler than dark brown postpedicel; postpedicel length less than 4× basal width; stylus cylindrical, shorter than basal width of postpedicel; apical mechanoreceptor one-third length of stylus.
Thorax
: Dense grey pruinescence. Scutum with pair of narrow dark brown vittae between acrostichals and dorsocentral rows (viewed anteriorly) (Fig.
Legs
: Brown, apex of femora, base of tibiae and proximal half of tarsomere 1 yellowish; apical tarsomeres increasingly darker (Fig.
Wing (2.6–3 mm): Broad, anal lobe nearly right-angled; alula well-developed. Costal margin at humeral crossvein expanded, costal cell broad; costa gradually reduced beyond M1; spur vein arising from cell bm. Halter knob pale.
Abdomen : Brown with thin grey pruinescence; setae pale. Female terminalia (undissected): Cercus short, truncate; hypoproct paler than cercus.
Unknown.
Formal naming of this species should await association of male specimens.
1 | Alula undeveloped; acrostichals biserial; scutellum with two pairs of setae; males dichoptic | S. tumbinensis |
– | Alula developed (Fig. |
2 |
2 | Scutum with 3 broad, brown faint stripes beneath acrostichals and dorsocentrals; scutellum with four pairs of setae, much longer than length of scutellum; legs brown with pale “knees” | S. secunda |
– | Scutum with pair of dark vittae between rows of acrostichals and dorsocentral setae (Fig. |
3 |
3 | Legs yellow (Fig. |
S. namibiensis sp. nov. |
– | Legs yellowish-brown (Fig. |
Stuckenbergomyia species A (females only) |
The subfamily assignment of Stuckenbergomyia has been problematic since the recognition of this enigmatic genus.
In all studied genera of Hybotidae, the spermatheca is stated to be either absent (i.e. not readily observed) or is membranous and unpigmented (
I am indebted to the following curators and their respective institutions for the loan of specimens: Ashley Kirk-Spriggs (