A revision of the Afrotropical genus Prytanomyia Özdikmen , 2006 ( Asilidae , Laphriinae )

The monotypic Afrotropical genus Prytanomyia Özdikmen, 2006 is revised. Laphystia kochi Lindner, 1973 is found to belong to Prytanomyia and is identical to Prytanomyia albida (Oldroyd, 1974), type of the genus. As a consequence L. kochi is newly combined with Prytanomyia, and P. albida is placed in the synonymy of P. kochi. The species inhabits arid environments, is restricted to the Namib desert from southern Angola to southern Namibia, and is found on vegetated sand mounds and dunes and in dry riverbeds. The highly reduced pulvilli, characteristic of this species, are believed to be an adaptation to living and perching on sandy surfaces.


Introduction
During preliminary research on the Afrotropical asilid genus Laphyctis Loew, 1879, to which previously described Afrotropical Laphystia Loew, 1847 species have been assigned (Londt 1988), and identifying newly collected material of Prytanomyia Özdikmen,

Materials and methods
Terminology follows that proposed by McAlpine (1981), Cumming and Wood (in press), Stuckenberg (1999), Wootton and Ennos (1989, wing venation) as well as that used by the senior author in more recent publications.Specimens available for study are housed in the following institutions: personal collection of Fritz Geller-Grimm, Frankfurt, Germany (COGG), Illinois Natural History Survey, Urbana-Champaign, IL, U.S.A. (INHS); The Natural History Museum, London, U.K. (BMNH); Kwa-Zulu-Natal Museum, Pietermaritzburg, South Africa (NMSA); Staatliches Museum für Naturkunde, Stuttgart, Germany (SMNS); National Museum of Natural History, Washington, DC, U.S.A. (USNM).When possible, label data is cited as it appears on labels; inverted commas indicate separate labels while lines of data may be separated by a slash (/).While more recently collected specimens are often provided with detailed information relating to locality and habitat, it has been necessary to attempt to establish precise geographic coordinates for older or relatively poorly documented material in order to gain a better appreciation of distribution.Google Earth and the Internet have been used to accomplish this.Information not appearing on labels is provided in square brackets.A wing was removed, placed in alcohol and flattened between glass microscope slides for photography before being reunited with the specimen.Terminalia were excised and macerated in hot Potassium Hydroxide (KOH) before being drawn with the aid of a drawing tube.The terminalia were then stored in a micro-vial containing a mixture of ethanol and glycerine and attached to the specimen's pin.The majority of photographs of pinned specimens are available in digital format at Morphbank (Collection ID #860905).The distribution map is available in digital format at SimpleMappr and Google Earth.
Thorax: Dark red-brown, uniformly strongly silver pruinose, white setose.Pronotum dark red-brown, silver pruinose, white setose.Mesonotum dark red-brown, entirely silver pruinose, uniformly fine white setose.Dorsocentral setae poorly developed and mostly evident postsuturally.Lateral macrosetae white, 3 npl, 2-3 spal, 2-3 pal.Scutellum dark red-brown, fine silver pruinose (weakly anteriorly and along posterior margin), c. 20 fine, white, erect apical scutellar macrosetae.Pleura dark  Abdomen: Dark red-brown to black, white setose, silver pruinose.Tergites (♂ with 6 well-developed and clearly evident, others reduced and hidden from view underneath T6; ♀ with 8 visible tergites) dark red-brown to black, white setose, especially laterally, silver pruinose posterolaterally, apruinose anteromedially.T1-6 with white discal macrosetae (progressively diminishing in number from T1 to T6).Sternites red-brown with brown-yellow posterior margins, fine white setose, fine dull silver pruinose.♂ terminalia (Figs 12-14): Genital bulb rotated c. 15-45° clockwise or anticlockwise.T7-8 and S7-8 reduced and poorly defined.Epandrium large, in dorsal view almost twice as long as broad and widely bilobed in distal quarter (Fig. 12) and with minor projections either side of base of proctiger.Proctiger short, fairly broad, projecting only slightly beyond distal epandrial margin in dorsal view.Hypandrium in ventral view subcircular (Fig. 14),  poorly defined, almost transparent, margins difficult to appreciate; in lateral view bent at an almost right angle proximally such that it is clearly separated from the gonocoxites (Fig. 12).Gonocoxites well developed, clearly bilobed, broader than epandrium in lateral view (Fig. 12) and more than half as long as epandrium.Gonostyli laterally compressed, subdivided into two lobes, a narrow dorsal lobe with darkly sclerotized ventrally hooked terminal point, and a broad S-shaped ventral lobe with dorsally hooked distal end.Aedeagus with long, gently sinuous distal shaft reaching level of proctiger, tip rounded (details difficult to see).♀ terminalia (Fig. 15): Relatively broad and somewhat dorsoventrally flattened.Segments 1-6 well developed, segments 7-8 reduced, but clearly evident.Subgenital plate moderately well-developed, broader than long, with undulating, distal margin displaying two pairs of lobes separated by a depressed area.Proctiger with dorsal lamellae wider than ventral lamellae.Note: On dissection the abdomen was found to contain a few semi-spherical eggs with a diameter of c. 0.5 mm (Fig. 16).
Notes on original descriptions.Laphystia kochi: Lindner (1973) studied only three female specimens, one from Gobabeb, and two from Swakopmund (localities well represented by material in the NMSA and USNM).Both were collected in February, as was the NMSA and USNM material.His description, in German, is detailed and agrees in all important ways with that presented above.Interestingly Lindner fails to mention the poorly developed pulvilli although these are evident in his photograph of one of the specimens.Lindner did not designate a holotype and so his specimens must be regarded as syntypes.Lindner named the species for Dr Charles Koch, founder of the Gobabeb Research Station in Namibia, where he collected a specimen.
Prytania albida: Oldroyd's (1974) description is good and there is no doubt that the material available from several museums agrees fully with his types.The type locality is Swakopmund from which many specimens have subsequently been collected.
Type material.Lindner (1973) listed his material of Laphystia kochi as '1♀ Gobabeb, SWA, 2-8.II.1970;2♀ Swakopmund, 29-30.II.1970', but the two specimens from Swakopmund are labelled as having been collected on different days as shown below.As Lindner failed to designate a holotype and in order to preserve stability we hereby designate one of the three female specimens as Lectotype   The majority of collecting records are for February (179) with a few records (15) for late January.Eight specimens were collected in mid-to late November (at Gobabeb and south of Walvis Bay) and a single specimen was collected in early December (at Gobabeb).Although the number of specimens included in this study is high (203), most were collected over very limited periods of time as well as only during a few collecting events, and so the species may be active for far longer than presently appreciated.Material bearing information relating to the known habitat of P. kochi strongly suggests that these flies are associated with vegetated sand mounds and dunes or sandy, dry, riverbeds .The highly reduced pulvilli support this contention and it is predicted that these flies rest almost entirely on sandy surfaces much like other species with poorly developed pulvilli, or entirely lacking these structures (see discussion in Londt and Copeland 2017).
Virtually nothing is known of the biology of Prytanomyia and only three prey records are available.Three female specimens are pinned together with their tiny prey -Diptera (2), Hymenoptera (1).Of the 201 recorded specimens, 69 (34%) are males and 132 (66%) females, suggesting a possible imbalance in sexual representation.Prytanomyia is a distinctive member of the Laphriinae and can be easily placed within this taxon even though it has not been included in the most recent phylogeny of Asilidae by Dikow (2009).It is not immediately recognized as a member of this clade though, in part due to the highly reduced pulvilli, which is quite a unique feature

Figure 17 .
Figure 17.Map of southern Africa with elevational relief and distribution of Prytanomyia kochi.Type locality with square symbol (SimpleMappr 7675).
Oldroyd, 1974sly recorded material.Types and other specimens of Prytania albidaOldroyd, 1974, in the BMNH, are as follows: