Subacuminiseta, Papp, László, 2014

Papp, László, 2014, New genera of Afrotropical limosinine sphaerocerids (Diptera: Sphaeroceridae), Zootaxa 3764 (2), pp. 101-130 : 127-128

Subacuminiseta gen. nov.

( Figs 107–118 )

Type species: Subacuminiseta minor sp. nov., by present designation.

Gender: feminine.

Etymology. The name of the new genus is composed from the Latin ‘sub’ (= under) and the genus name Acuminiseta , a genus where it has some similarity in body characters.

Diagnosis. A very small fly with particularly sparse setae on body and legs. It is characterised by a special set of features: it has no postocellar seta, its costal vein thickened, projecting far beyond apex of R4+5, it has only 1 pair of dorsocentral setae, there is no mid ventral seta on mid tibia, its male mid tibia is without a row of antero-ventral setae; its male genitalia are also unique with basiphallus and distiphallus large thick and strongly fused to each other ( Fig. 113 ), this complex is with 2 very large ventral processes, which I would not name as epiphallus or preepiphallus, its postgonite large with two apices. In female tergite 8 not divided, epiproct very weakly sclerotised with a pair of weak central pair of setae, sternite 8 very small, weakly sclerotised in 2 transverse parts, cercus oblique with several short apical and subapical setae, its spermathecae are subequal pear-shaped. As for its position in Papp’s (2008) key, there is a bias between couplet 29 and 31: arista is very long but not long-haired. It seems better to follow couplet 29; if so, male fore claw normal, and only 2 pairs of long interfrontal setae present. That is, our new genus keys to Paracuminiseta L.Papp , but it differs from Paracuminiseta in the characters described above.

Description. Head. Two pairs of fronto-orbital setae, posterior pair slightly reclinate, ocellar seta and 2 pairs of interfrontal setae strong (at most a 3rd minute ifr on the right side). No inner orbital setae. Both outer and inner vertical setae normal, outer and inner occipitals minute. Neither postocellars nor postoculars developed. No genal seta, 4–5 weak peristomals present. Antenna not in a hollow, facial plate protruding medially. Pedicel of antenna ( Fig. 107 ) actually longer than first flagellomere, its central apical process characteristically long. First flagellomere with a distinct dorsal apical apex, but that apex not sharp. Arista long, shortly ciliate and not apically placed; basal aristomeres comparatively long.

Thorax. Scutellum without additional setae. Only 1 pair of posterior dorsocentral setae. Anepisternum bare.

Legs with short and sparse setae. Mid tibia without ventral preapical or mid ventral seta, ventroapical seta comparatively strong. No posterodorsal seta in basal half of mid tibia.

Wing unicolorous, not even crossvein clouded. Costal vein thickened and much overruns (continued over) apex of R4+5, vein R4+5 bent up in an arch.

Male sternite 5 ( Fig. 108 ) with a large medio-caudal, less sclerotised part, which covered by fine dense hairs. Synsternite ( Fig. 109 ) with a very short narrow sternite 6 part and a large broad sternite 8 part; sternite 8 part with 2 thick marginal setae. Epandrium ( Fig. 110 ) with a large ventro-caudal process, epandrial complex broadly fused caudally, cercus lengthened ventrally with a long seta. Hypandrium comparatively weak, arms rather thin but fused to epandrium and strongly connected to postgonites ( Fig. 115 ); medial part of hypandrium weakly sclerotised and not longer than arms. Subepandrial sclerite ( Fig. 111 ) much broader than high. Surstylus ( Fig. 110 ) shorter than high with a ventral process, which bears an anteriorly directed thorn, surstylus otherwise simple with several setae. Basiphallus and distiphallus large, thick and strongly fused to each other ( Fig. 113 ), similarly to that of the Oriental Pseudoacuminiseta ( Papp 2008: fig. 280). The complex has 2 very large ventral processes, which I would not name as epiphallus or pre-epiphallus. Basiphallus in caudal view with a broad though less sclerotised lobe ( Fig. 114 ). Distiphallus deeply divided in its apical part. Phallapodeme ( Figs 113–114 ) with a basal discus-shaped thickening, similarly to that in some Ceroptera spp. Also postgonite ( Fig. 115 ) peculiar: large with two apices: anterior apical process simple but pointed, posterior process long curved and caudally directed.

Female. Tergite 8 ( Fig. 116 ) not divided, epiproct very weakly sclerotised with a pair of weak central pair of setae. Cercus ( Fig. 116 ) oblique with several short apical and subapical setae. Sternite 8 very small, weakly sclerotised in 2 transverse parts. Epiproct very weakly sclerotised. Hypoproct small ( Fig. 117 ). Spermathecae ( Fig. 118 ) pear-shaped but distal end with a bulb each, sclerotised part of ducts extremely short with another bulb each; not sclerotised part of ducts are very thin.

Figures

FIGURES 107 – 112. Subacuminiseta minor sp. n., antenna, male postabdomen and genitalia. 107 = antenna, lateral view, 108 = sternite 5, ventral view, 109 = synsternite, ventral view, 110 = surstylus in broadest (subanterior-sublateral) view with right half of epandrium, 111 = subepandrial sclerite, inner (anterior) view, 112 = cerci, broadest (subcaudal) view. Scale bars: Fig. 107 = 0.2 mm, Figs 108 – 112 = 0.1 mm.

FIGURES 113 – 118. Subacuminiseta minor sp. n., male and female genitalia. 113 – 115 = holotype male: 113 = phallus and phallapodeme, left lateral view (basiphallus partly embraces distiphallus), 114 = distiphallus and phallapodeme with contour of distiphallus, dorsal view, 115 = right postgonite with right hypandrial arm slightly pushed into the plane of postgonite. 116 – 118 = paratype female: 116 = tergite 8, epiproct (very weakly sclerotised) and cerci, dorsal view, 117 = sternite 8 (!) and hypoproct, 118 = spermathecae. (S 8: sternite 8, T 8: tergite 8). Scale bar: Figs 113 – 118 = 0.1 mm.