Stylogaster kakamegensis, Stuke, 2012

Stuke, Jens-Hermann, 2012, A revision of Afrotropical species of Stylogaster Macquart (Diptera: Conopidae), with descriptions of twenty-one new species and an identification key, African Invertebrates 53 (1), pp. 267-267 : 304-307

Stylogaster kakamegensis sp. n.

Figs 115–124

Etymology: The species is named after the locus typicus, Kakamega Forest in western Kenya and the surrounding area of highly endangered tropical rainforest.

Diagnosis: Stylogaster kakamegensis sp. n. belongs to a group of species occurring in central and East Africa, that lack additional outstanding setulae on the mid femur and have a mainly black mesoscutum ( Fig. 115 ), partly brown tergites and tergite 6 almost completely brown. There are two additional species in this group, viz. S. kenyensis sp. n. and S. nitens . The former species can be separated on the basis of the pale yellow-brown margin of the mesoscutum ( Fig. 125 ) and the elongated pedicellus, being longer than the basal flagellomere ( Fig. 126 ). The later species can by separated by the structure of the ♂ terminalia, as illustrated by Stuckenberg (1963: 270, figs 10, 13, as parva ) and Smith (1967: 57, fig. 40), having no teeth at the distal margin of the surstylus, a different form of the surstylus and black setae at the base of the phallus sheath of the hypandrium.

Description (based on holotype):

Male.

Overall length ca 6.5 mm.

Head: 1.2 mm high. Eye dark brown, with a few scattered inconspicuous ommatrichia. Facets on the inner side slightly enlarged. Ocelli yellow­brown. Ocellar tubercle blackish brown, paired ocellar setae could be located. Ocellar triangle occupies virtually entire frons and reaches as far as antennae ( Fig. 117 ). Ocellar triangle dark brown. Frons lateral to ocellar triangle dark brown with a single fronto-orbital seta discernible. Scapus and pedicellus orange­brown, basal flagellomere brown.Arista dark brown, 3 segments evident. Arista situated dorsally at apex of basal flagellomere ( Fig. 116 ). Scapus without conspicuous setulae. Pedicellus with black setulae. Shape of antenna as illustrated in Fig. 116 . One damaged vertical seta. Face pale yellow with silver pruinosity. Occiput black and only slightly pruinose; with row of regularly-arranged small black setulae dorsally, and with very few white setulae ventrally. Some long white setulae on mouth opening. Proboscis pale brown basally, becoming blackish brown distally, except for yellow-brown distal division of labellum. Labrum ca 1.7 mm, labellum approximately same length.

Thorax: Yellow-brown; the mesoscutum (with exception of postpronotum and postalar callus), scutellum and mediotergite black.All undamaged setae black. Two notopleural setae, 1 damaged supra-alar seta, 2 postalar setae, 1 praescutellar dorsocentral seta, 1 apical scutellar seta, no seta on anepimeron and 1 seta above fore coxa on propleuron. All setae on left side damaged, except praescutellar dorsocentral seta and apical scutellar seta. Black semi-adpressed setulae on mesoscutum.

Wing: Length 4.6 mm. Generally clothed in microtrichia, except for base of sc, base of r 1 and very narrowly at base of r 2+3, br, bm, very narrowly at base of dm and cup. Hind margin of wing with black or brown setulae. Venation as in Fig. 118 . Haltere uniformly yellow-brown basally, knob brown, with areas of sensillae at base.

Legs: Fore and mid legs yellow­brown. Hind leg darker, with brown dorsal surface of hind femur and brown hind tarsi. Legs mainly with black or brown setulae and black setae, only fore tibia additionally with pale yellow setulae. Fore and mid coxae each with 1 distinct black seta. Hind coxa distally on anterior surface with strong brown setulae, without outstanding lateral seta. Hind trochanter without teeth or dense setulae. Mid femur posteriorly on basal half with row of regularly-arranged pale brown setulae. Hind tibia with 2 short black spines on anterior surface. Claws brown basally, distally black. Pulvilli pale brown. Empodia short, pale brown.

Abdomen: Mainly orange-brown, tergites 1–2 entirely brown, tergites 3–4 with brown posterior margins and brown fascia medially, tergite 5 with broad brown fascia medially and tergite 6 brown with except for lateral margins. Tergites with semi-adpressed black setulae. Tergite 1 with long black setulae laterally, tergite 2 on anterior margin with 3 black lateral setae on either side. Terminalia as illustrated in Figs 119–124 . Cercus short, rounded distally ( Fig. 123 ). Dorsal margin slightly concave. Cercus with lappet ventrally that bears conspicuous, strong, short setulae. Surstylus with 1 short black tooth on distal margin ( Fig. 119 ). A small field with long, erect, setulae on inner surface ( Fig. 121 ). Phallus sheath as illustrated in Fig. 122 .

Female. Unknown.

Holotype: ♂ KENYA: (1) “ Kakamega / forest, / 5200 feet ”; (2) “Kenya: / 18 xii.1970 / A.E. Stubbs / B.M. 1972–211”; (3) “ Holotypus / Stylogaster / kakamegensis ♂ / des. Stuke, 2011” ( BMNH). Right fore and mid tarsi and some setae damaged, right arista missing. Abdomen dissected, macerated and deposited in glycerine in a microvial pinned beneath specimen, holotype otherwise in reasonable condition.

Distribution: Known only known from Kakamega Forest in western Kenya.

Bionomics: Sampled from the Kenyan last remnant of the ancient Pan-African forest.

Figures

Figs115–118.Stylogaster kakamegensis sp.n.(♂ holotype):(115) thorax,dorsal view; (116) antenna, lateral view; (117) frons; (118) wing. Not to scale.

Figs 119–124. Terminalia (♂) of Stylogaster kakamegensis sp. n. (♂ holotype): (119) surstylus, lateral view; (120) same, dorsolateral view; (121) same, ventral view; (122) phallus sheath of hypandrium, lateral view; (123) cercus, lateral view; (124) sperm pump and ejaculatory apodeme.Abbreviations: bp – basiphallus; ce – cercus; ep – epandrium; hys – phallus sheath of hypandrium; su – surstylus. Not to scale.

Figs 125–128. Stylogaster kenyensis sp. n. (♂ holotype): (125) thorax, dorsal view; (126) antenna, lateral view; (127) frons; (128) wing. Not to scale.