Prytanomyia kochi (Lindner, 1973) Lindner, 1973

Londt, Jason G. H. & Dikow, Torsten, 2017, A revision of the Afrotropical genus Prytanomyia Oezdikmen, 2006 (Asilidae, Laphriinae), African Invertebrates 58 (2), pp. 39-52 : 42-49

Prytanomyia kochi (Lindner, 1973) comb. n. Figs 1-2, 3-4, 5-10, 11, 12-16, 17

Laphystia kochi Lindner, 1973: 74 (fig. 1 Entire ♀). http://zoobank.org/F60777CD-C8F2-43E0-9D4C-DAF4EF624495

Laphyctis kochi (Lindner, 1973), Londt 1988: 513.

Prytania albida Oldroyd, 1974: 112 (fig. 105 Entire ♂) syn. n.http://zoobank.org/79557160-03D9-412F-9799-90DD93FF1EEB

Redescription.

Based on all available material. General appearance as in Figs 1-10. Note: Slight sexual dimorphism occurs in the colour of antennae and legs and pubescence of abdominal tergites.

Head: Dark red-brown, colour masked by strong silver pruinescence, shiny white setose. Antennae mostly dark red-brown, scape red-brown in ♂, dark brown-yellow in ♀, pedicel brown-yellow, postpedicel and stylus dark red-brown, fine silver pruinose. Scape strongly white setose ventrally, pedicel weakly white setose. Postpedicel with fairly narrow terminal cup-shaped stylus with oblique opening and enclosing a seta-like sensory element. Segmental length ratios (scape (as 1): pedicel: postpedicel: style) - 1: 0.5: 2.2: 0.5. Eye smoothly oval in lateral view, ommatidia of fairly uniform size over entire surface. Face dark red-brown, colour masked by strong silver pruinescence. Width of one eye: face ratio 1: 1.4 (face clearly wider than eye - Figs 4, 7-8). Face with gently convex profile, projecting weakly at mid height. Mystacal setae numerous (no obvious macrosetae), shiny white, covering most of face although more sparsely dorsally. Frons and vertex dark red-brown, colour masked by shiny silver pruinescence, extensively white setose. Ocellar tubercle weakly protuberant, fine white setose (no obvious macrosetae). Postocular (occipital) region dark red-brown, colour masked by strong silver pruinescence. Occiput with rows of c. 15 white macrosetae dorsally behind each eye and many fine, shiny white setae. Palpi dark red-brown, 2-segmented, weakly fine white setose. Proboscis straight, circular in cross-section, shiny dark red-brown, fine white setose proximally and distally.

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 red-brown, entirely silvery pruinose, white setose. Katatergal macrosetae, numerous, moderately developed, white. Anatergites uniformly strongly silver pruinose, asetose. Postmetacoxal area membranous. Legs: Coxae dark red-brown, silver pruinose, white setose. Femora, tibiae and tarsi fairly uniformly orange, except for dorsal parts of femora and metathoracic tibiae in ♂ which are commonly partly red-brown, shiny white setose. Claws well developed, black with brown-orange basal parts. Empodium white, straight, slightly shorter than claws. Pulvilli pale yellow, poorly developed, about ½ as long as claws. Wings (Fig. 11): length measured from humeral crossvein to tip, breadth at widest level: Males (10) 3.9 × 1.4 - 5.2 × 2.1 mm (mean 4.6 × 1.7 mm), females (10) 4.6 × 1.7 - 6.9 × 2.6 mm (mean 5.4 × 2.1 mm). Females on average slightly bigger than males. Venation: Marginal cells open (notably r1) except for m3 and cua, which are closed and stalked. Vein M3 unusually weakly developed at base (enclosing discal cell d). Veins pale yellow anteroproximally, brown posterodistally, membrane unstained, transparent, lacking microtrichia. Costa (C) apparently terminating at junction of veins CuA and CuP with wing margin. Cell cup and alula with weak bordering microsetae.

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 (Figs 3-4). The other two specimens are considered paralectotypes.

Lectotype. NAMIBIA: 1♀ ' Sovakopmund [misspelling of Swakopmund c. 22°41'18"S, 14°32'02"E, 10m] SWA. / 29- 30.2. 1970 / Lindner leg.' [blue], ' Laphystia / kochi Lind. / Lindner det.' [white], 'Syntype / Laphystia / kochi Lind. / Det. J. Londt.', ‘AAM-007677’ ( SMNS) .

Paralectotypes. NAMIBIA: 1♀ ' Swakopmund / SWA. 31.1.1970 / Lindner leg.' [blue], ' Laphystiella / kochi Lind. / Lindner det.', 'Syntype / Laphystia / kochi Lind. / Det. J. Londt.', ‘AAM-007678’ ( SMNS) ; 1♀ ' Gobabeb [c. 23°33'47"S, 15°02'25"E 395m] SWA. / 2- 9.2.1970 / Lindner leg.' [blue], ' Laphystia / sp nov. / det H. Oldroyd 1970' [white], ' Laphystia / kochi Lind. / Lindner det.', 'Syntype / Laphystia / kochi Lind. / Det. J. Londt.', ‘AAM-007678’ ( SMNS) .

Other previously recorded material. Types and other specimens of Prytania albida Oldroyd, 1974, in the BMNH, are as follows:

Holotype. NAMIBIA: 1♂ ’Holotype’, 'S.W. Africa (25), Swakopmund [c. 22°41'18"S, 14°32'02"E, 10m], 26 –30.i.1972’, ' Southern African Exp. B.M. 1972 –1’, ' Prytania albida Old. det. H. Oldroyd Holotype’, ’NHMUK010292241’ .

Paratypes. ANGOLA: 1♀ 'Angola (A15) R. Giraul [c. 15°04'43"S, 12°17'28"E, 65m] 10 mls. NE. Mocamedes 27 –29.ii.1972’, ' Southern African Exp. B.M. 1972 –1’, ’NHMUK010292263’ ; 3♀ ’Paratype’, ' Angola (A8) 2 mls. S. Mocamedes [= Namibe c. 15°10'02"S, 12°09'32"E, 5m] 24 –25.ii.1972’, ' Southern African Exp. B.M. 1972 –1’, 'Paratype Prytania albida Old. det. J.E. Chainey 1986', ' NHMUK010292251 , NHMUK010292256 , NHMUK010292259 ' ; 2♂ 2♀ ’Paratype’, ' Angola (A10) R. Curoca 7 mls. NE . [c. 15°43'52"S, 11°55'27"E, 10m] P. Alexandre 25 –26.ii.1972’, ' Southern African Exp. B.M. 1972 –1’, 'Paratype Prytania albida Old. det. J.E. Chainey 1986', ' NHMUK010292250 , NHMUK010292253 , NHMUK010292257 , NHMUK010292258 ' ; 2♀ ' Angola (A9) Porto Alexandre [= Tombua c. 15°48'15"S, 11°50'42"E, 10m] 25.ii.1972 ', ' Southern African Exp. B.M. 1972 –1’, ' NHMUK010292261 , NHMUK010292262 ' ; NAMIBIA: 3♂ 7♀ ’Paratype’, 'S.W. Africa (25) Swakopmund [as for holotype] 26 –30.i.1972’, ' Southern African Exp. B.M. 1972 –1’, 'Paratype Prytania albida Old. det. J.E. Chainey 1986', ’NHMUK010292241–, NHMUK010292254 –NHMUK010292255’ ; 1♂ ’Paratype’, 'W. Africa (24) Walvis Bay [c. 22°57'22"S, 14°30'29"E, 10m] 25 –26.i.1972’, ' Southern African Exp. B.M. 1972 –1’, 'Paratype Prytania albida Old. det. J.E. Chainey 1986', ’NHMUK010292252’ ; 1♂ 'S.W. Africa (23) Homeb [c. 23°38'12"S, 15°10'55"E, 435m] 10 mls. ESE Gobabeb 23 –25.i.1972’, ' Southern African Exp. B.M. 1972 –1’, ’NHMUK010292260’ .

Previously unrecorded material examined: NAMIBIA: Erongo: 2♂ 14♀ 'South West Africa 2113Ba / Swakopmund Dist. Ugab / River Mouth [c. 21°11'13"S, 13°37'47"E], 8 m. 7.ii.1974 / ME & BJ Irwin, vegetated / sand mounds nr. coast’ (♂ NMSADIP08395 , NMSADIP71654 ♀ NMSADIP08374 , NMSADIP08389 , NMSADIP71655-66 ) ( NMSA) ; 5♂ 15♀ Namib–Skeleton Coast National Park, off C34 N Cape Cross , 21°43'40"S, 013°58'48"E, 3 m, 2012-02-02, coastal vegetated dunes, perching on sand, Dikow, T. ( USNMENT00832290-1 , USNMENT00832293-5 , 00832297-310 , USNMENT00832312 ) ( USNM) ; 4♂ 3♀ Namib-Skeleton Coast National Park, N Omaruru River mouth , 22°05'19"S, 014°15'09"E, 8 m, 2012-02-02, coastal vegetated dunes, perching on sand, Dikow, T. ( USNMENT00832311 , USNMENT00832313-8 ) ( USNM) ; 1♂ Swakopmund , 22°41'09"S, 014°31'51"E, 1990-02-12, Schwartz, M. ( COGG) ; 28♂ 27♀ 'South West Africa 2214Da / Swakopmund Dist. Swakop / River Mouth [c. 22°41'21"S, 14°31'36"E], 8 m. 9.ii.1974 / ME & BJ Irwin, coastal / and riverbed dunes’ (♂ NMSADIP71667-94 , ♀ NMSADIP08327 , NMSADIP08390 , NMSADIP71695-719 ) ( NMSA) ; 5♂ 7♀ Swakopmund, S side Swakop River mouth, 22°41'33"S, 014°31'37"E, 9 m, 2012-02-03, sandy river bed and vegetated dunes, perching on sand, Dikow, T. ( USNMENT00832319-29 , USNMENT00832334 , USNMENT00832338 ) ( USNM) ; 1♂ 3♀ B2 Swakopmund-Walvis Bay , 22°44'42"S, 014°31'27"E, 6 m, 2012-02-04, coastal vegetated dunes, perching on sand, Dikow, T. ( USNMENT00832331 , USNMENT00832335-6 , USN MENT 00832343 ) ( USNM) ; 6♂ 13♀ 'South West Africa 2214Dc / Swakopmund Dist. 12 km. N. Walvis Bay [c. 22°51'43"S, 14°32'35"E], 3 m. 10.ii.1974 / ME & BJ Irwin, vegetated / mounds and dunes’ (♂ NMSADIP08397 , NMSADIP71720-24 , ♀ NMSADIP08329 , NMSADIP08380 , NMSADIP71725-35 ) ( NMSA) ; 1♀ Walvis Bay , 22°57'22"S, 014°30'29"E, 1990-02-22, Schwartz, M. ( COGG) ; 5♀ Namibia Walvisbaai [= Walvis Bay] , 5 km S (c. 23°01'02"S, 014°27'54"E), 5 m / 22.xi.1996, low dunes, M.E. Irwin ( INHS-713233-5 ) ( INHS) ; 1♂ Gobabeb, Namib Desert Research Station , 23°33'37"S, 015°02'26"E, 1983-11-17, Moore, A. ( USNMENT00802354 , USNM) ; 1♂ 4♀ 'South West Africa 2315Ca / Namib Desert Park, Kuiseb / River at Gobabeb [c. 23°33'47"S, 15°02'25"E]. 400m. / 12.ii.1974, ME & BJ Irwin / Riverine forest and sand’ (♂ NMSADIP71736 , ♀ NMSADIP08388 , NMSADIP71737-9 ) ( NMSA) ; 1♀ Namib-Naukluft Park, Namib Desert Research Station, Kuiseb River , 23°33'45"S, 015°02'38"E, 420 m, 22.xi.1996, M.E. Irwin ( INHS-33542 ) ( INHS) ; 1♂ 'SWA Kuiseb R. [probably as above] / 9.xii.1976 / AB Cunningham’ ( NMSADIP08400 ) ( NMSA) ; 1♀ Namib-Skeleton Coast National Park, Gobabeb, Kuiseb riverbed , 23°33'47"S, 015°02'22"E, 396 m, 2012-02-06, perching on sand, Dikow, T. ( USNMENT00832344 , USNM) ; 5♀ Namib-Skeleton Coast National Park, Homeb , 23°38'34"S, 015°10'55"E, 445 m, 2012-02-06, dune, perching on sand, Dikow, T. ( USNMENT00832332 , USNMENT00832337 , USNMENT00832340 , USNMENT00832342 , USNMENT00832346 ) ( USNM) ; 1♀ Namib-Skeleton Coast National Park, Homeb , Kuiseb riverbed , 23°38'34"S, 015°11'21"E, 430 m, 2012-02-06, perching on sand, Dikow, T. ( USNMENT00832341 ) ( USNM) ; Karas: 6♂ 13♀ 'South West Africa 2615Ca / Lüderitz Dist. Agate / Beach [c. 26°36'23"S, 15°10'37"E], 10 km. N. Lüderitz, 3 m. / ME & BJ Irwin. 18.ii.1974 / on coastal vegetated dunes’ (♂ NMSADIP71740-5 , ♀ NMSADIP08386 , NMSADIP71746-57 ) ( NMSA) .

Distribution, phenology and biology. The distribution of Prytanomyia is illustrated in Fig. 17. With exception of the Gobabeb and Homeb records all can be considered coastal. Gobabeb and Homeb are situated inland on the east side of the Namib desert dunes, but on the banks of the Kuiseb River which eventually runs into the Atlantic ocean at Walvis Bay. At Gobabeb, specimens were caught in the dry Kuiseb riverbed (Fig. 22) by M. Irwin and the junior author (other collecting events lack habitat detail) and this environment is similar to the Swakop and Omaruru river mouths (Figs 19-20) on the coast. The majority of specimens at Homeb though were collected on the large dunes adjacent to the Kuiseb riverbed (Fig. 21, only a single specimen in the dry Kuiseb riverbed), which is quite different from the coastal dunes at river mouths. The small sand mounds (Fig. 18) from which M. Irwin and the junior author collected the species (other coastal collecting events lack habitat detail) are also quite a different habitat from the larger sand deposits or dunes at river mouths. It can be hypothesized that the species will inhabit the Namib dune fields away from the coast that exist between southern Angola and Lüderitz in southern Namibia and of which the internal dunes and intervening valleys have rarely been sampled for insects.

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 (Figs 18-22). 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.