Trichardis nigrescens ( Ricardo, 1903 )

Londt, Jason G. H., 2008, A review of Afrotropical Trichardis Hermann, 1906, and the description of the first Oriental representative of the genus (Diptera: Asilidae: Laphriinae), African Invertebrates 49 (2), pp. 171-171 : 193-194

Trichardis nigrescens ( Ricardo, 1903)

Figs 33, 34

Hoplistomera nigrescens: Ricardo 1903: 362 .

Trichardis nigrescens: Hull 1962: 97 ; Oldroyd 1980: 356 (catalogue); Geller-Grimm 2002: 470, pls 3, 17

(entire ơ).

Redescription (based on holotype ^in good condition):

Head: Dark red-brown, extensively silver pruinose except for lower face and frons (including ocellar tubercle), black and white setose.Antenna red-brown, black and pale yellow setose; postpedicel elongate spindle-shaped (L:D=5.3:1). Mystax mainly white with a few black macrosetae along epistomal margin. Ocellar tubercle with 4 yellowish macrosetae. Some black occipital macrosetae. Proboscis and palpi dark red-brown.

Thorax: Dark red-brown, silver pruinose when present, pale whitish setose. Postpronotum dark red-brown with small orange part posteriorly, largely apruinose except for medial part, mesonotum largely apruinose except for lateral and posterior margins, macrosetae black (notopleurals) and whitish, setulae shiny white. Scutellum apruinose except for narrow anterior margin. Anepisternum with slender, weakly developed posterior macroseta, extensively pruinose except for small area anteroventrally. Proepimeron anteriorly pruinose, posteriorly apruinose; katepisternum posteriorly pruinose, anteriorly apruinose. Legs: Femora dark red-brown, other segments orange-brown, pulvilli and empodium of similar length. Hind femur dark red-brown, moderately slender (length to height ratio not measured), ventral tubercles poorly developed. Hind tibia lacking ventrodistal spur. Wing: 5.5× 2.1 mm. Costal vein extends along most of wing margin, weakly along anal cell, absent from alula. Membrane not extensively microtrichose—discal cell largely lacking microtrichiae (a few present), cell r 5 with microtrichiae in distal half only.

Abdomen:Anterior five terga dark red-brown with orange-brown hind margins, posterior terga and hypopygium mustard colour, apruinose except for silver pruinose posterolateral corners, setae whitish. T2 dark red-brown, apruinose except for silver pruinose posterolateral corner.

ơ genitalia: Geller-Grimm (2002: figs 2–4) illustrated a male from Socotra. I here illustrate the genitalia of an already macerated ơ from Homhil ( Figs 33, 34 ). While this is probably the specimen illustrated by Geller-Grimm, I believe that my drawings more accurately depict the genital structures and the subtle differences between nigrescens and abdelkuri , the closely similar species from the nearby island of Abd el Kuri. The following is a description of the Homhil ơ genitalia based on my illustrations. Epandrium in lateral view slightly longer than basal part of gonocoxite (i.e. excluding distal projection of gonocoxite and gonostylus). Proctiger moderately dorsoventrally compressed. Hypandrium greatly reduced and simple. Gonocoxite in ventral view without median projections distally and with mediodistally arranged macrosetae; mediodistal projection fairly slender with slightly upturned distal end. Gonostylus slender with straight distal end.Aedeagal prongs more or less straight and with small terminal tubules. Note:Although this description is similar to that of the genitalia of abdelkuri , the genital differences in these species can easily be detected by comparing the relevant illustrations. The shape of the gonocoxite in ventral view is particularly diagnostic.

Holotype (examined): YEMEN: Socotra I.: ^‘ Type’ [circular, red edged], ‘ Hoplistomera / nigrescens Ric. / 2^’, ‘Sokotra / Hadibu [12°40'N: 53°59'E] Plains. / 11.xii.1898 / W. R. O. Grant. / 1916-75.’ ‘ Holotype / Hoplistomera / nigrescens Ricardo / det. J. E. Chainey, 1984’ [has circular, red edged label stuck to top right corner of holotype label] (BMNH).

Other material examined: YEMEN: Socotra I.: 1 ơ Homhil, 12°34'13"N: 54°18'32"E, 29–30.x.2000, Pohl ( HLMD); 1 ơ 1^Goeeh, 12°32'25"N: 54°10'22"E, 240 m, 23.x.2000, Pohl ( HLMD) .

Recorded specimens not studied (cited from Geller-Grimm (2002)): YEMEN: Socotra I.: 2^Goeeh, 12°32'25"N: 54°10'22"E, 240 m, 23.x.2000, Pohl (NHCY 1^COGG 1^); 1^Firmihin, 12°24'41"N: 54°13'35"E, 34– 25.x.2000, Pohl ( HLMD); 1^Deksam, 12°32.298'N: 53°56.102'E, ca 300 m, 26.x.2000, Pohl ( HLMD); 2 ơ 1^Homhil, 12°32'N: 53°56'E, 9.i.1998, Wranik (CWWR, COGG 1 ơ) .

Distribution and biology: The species has been recorded only from four localities on the island of Socotra. Collections have been made in October, December and January (Table 1). No biological data have been recorded on specimen labels.

Similar species: T. nigrescens is superficially very similar to abdelkuri , but the species can be reliably separated on male genital features. Although I have seen relatively few specimens of both species, all specimens of abdelkuri have mesonotal, anepisternal and ocellar setae yellowish while these setae are mostly but not always black in nigrescens . These two species are somewhat similar to pohli , but easily separated on size and male genital form.

Figures

Figs 29–34. Trichardis species, male genitalia: (29, 30) lateral and ventral of T. malawi sp. n., paratype, Monkey Bay; (31, 32) lateral and ventral of T. mellina sp. n., paratype, Ghinda; (33, 34) lateral and ventral of T. nigrescens (Ricardo, 1903), Homhil. Scale lines = 1 mm.