Oligochaetosella, Papp, László, 2014

Papp, László, 2014, New genera of Afrotropical limosinine sphaerocerids (Diptera: Sphaeroceridae), Zootaxa 3764 (2), pp. 101-130 : 116-117

Oligochaetosella gen. n.

( Figs 62–74 )

Type species: Oligochaetosella inconspicua sp. nov., by present designation.

Gender: feminine.

Etymology. The generic name of this new genus is a diminutive form of the Latin name ‘oligochaetosus’ (with a few setae only).

Diagnosis. Minute flies with body not strongly sclerotised and not granulose. Both male and female genitalia are peculiar: its male sternite 5 broad and asymmetrical, the sternite 6 and 7 (forming part of synsternite) is extremely weak, the epandrium–cercus complex is open ventrally, cercal part subtriangular in caudal view, surstylus has a large apical and also a large caudal spine, hypandrium extremely weak, not to mention characteristics of the body. Female sternite 7 fused with sternite 8, this complex is nearly perpendicular to body axis. This new genus keys out to couplet 63 in Papp’s (2008) key for the Old World Limosininae . There it comes to a conflict: its vein R4+5 distinctly bent up to costa and the medial seta of scape as long as pedicel (cf. Australimosina L.Papp ).

Description. Head. Facial plate normal, antenna not in a hollow. No inner orbitals. Medial seta on scape almost as long as pedicel. First flagellomere not conical but with a round dorsal apex. First flagellomere with long cilia, which are longer apically, and so first flagellomere seems conical in lower magnification.

Thorax. Mesonotum with 1 pair of posterior dorsocentral setae only. Scutellum concolorous with the brown mesonotum. No additional scutellar setae. Anepisternum bare.

Legs. No preapical or mid ventral seta on mid tibia. Anteroventral and posteroventral setae on mid basitarsus are strong, but no longer seta among them. Hind tibia without longer setae.

Wing membrane unicolorous and without macrotrichia. First costal section with a pair of long setae sub-basally (though shorter than in Rudolfina ). Costal vein continued thinly but distinctly beyond apex of R4+5. Vein R4+5 strongly bent up to costa.

Male sternite 5 broad ( Fig. 62 ), medio-caudal part with a subquadrate field of fine short hairs in three slightly overlapping rows. Sternite 5 with sparse long setae, medially subcaudally numerous setae, which are perpendicular to sternal plane ( Fig. 63 ). Synsternite ( Fig. 64 ) with a very thin sternite 6 part and a large long sternite 8 part. Ratios in the male genitalia are unusual: surstylus and cercus very large compared to epandrium ( Fig. 68 ). Hypandrium short, medial part less strongly sclerotised ( Fig. 67 ). Epandrial complex broadly open ventrally. Cercus emerging ventrally with a number of medium-long setae. Subepandrial sclerite ( Fig. 65 ) narrow and high. Surstylus ( Figs 65– 66 ) higher than long, ventrally with a large blunt black tooth, posterobasally with a larger and thicker thorn and more caudally with a thinner thorn; surstylus outer lateral surface with numerous medium-long setae. Basiphallus large without epiphallus, distiphallus ( Figs 67–68 ) large bulbous, apically with a transverse large process, no peculiar dorsal structure. Phallapodeme long rod-like ( Fig. 67 ). Postgonite ( Figs 67–69 ) very broad-based, apical half slightly curved to the sagittal axis; apical part almost straight with a simple apex.

Female preabdominal sternites broad, e.g. tergite 3 0.40 mm, sternite 3 0.28 mm. Female postabdomen very short, not telescopic. Tergite 7 and sternite 7 though not fused, form a short ring (0.04–0.045 mm long, 0.18–0.20 mm broad). Tergite 6 and sternite 6 similar both in form and size but membrane between them broader. Tergite 8 in 2 lateral parts with some short setae and without medial process. Sternite 7 fused with sternite 8 ( Fig. 71 ), this complex is nearly perpendicular to body axis ( Fig. 70 ); sternite 7 part of the complex mostly covered by short hairs and with 2 pairs of longer setae, sternite 8 part bare with 2 pairs of minute setae. Epiproct ( Fig. 73 ) incised apically with a pair of fine setae. Hypoproct ( Fig. 72 ) all covered by short hairs. Cercus ( Fig. 73 ) extremely short subcylindrical with fine setulae only and with 3 pairs of short apical-subapical setae. Spermathecae ( Fig. 74 ) longer than broad, not strongly sclerotised (so they may collapse in glycerol), without any structures on surface. Sclerotised part of duct medium long on the unpaired one with a distal bulb, ducts shorter in paired ones with a medial (i.e. not distal) bulb.

Figures

FIGURES 62 – 67. Oligochaetosella inconspicua sp. n., male postabdomen and genitalia. 62 = sternite 5, ventral view, 63 = medio-caudal part of sternite 5 in higher magnification, 64 = synsternite, ventral view, 65 = subepandrial sclerite, cerci and right surstylus, caudal view, 66 = surstylus, broadest (sublateral-subcaudal) view, 67 = phallus, phallapodeme and postgonite, left lateral view. (BPh: basiphallus, C: cercus, DPh: distiphallus, HA: hypandrium, iS 8: inner surface of sternite 8, PG: postgonite, sscl: subepandrial sclerite). Scale bars: Figs 62, 64 = 0.2 mm, Figs 63, 65 – 67 = 0.1 mm.

FIGURES 68 – 74. Oligochaetosella inconspicua sp. n., male and female postabdomen and genitalia. 68 – 69 = male paratype: 68 = male genitalia, caudal view, 69 = postgonite, lateral view. 70 – 74 = female paratype. 70 = tergite 8 with contours of epiproct, cercus, hypoproct and sternite 7 + 8 complex, lateral view, 71 = sternite 7 fused with sternite 8, broadest (i. e. subcaudal) view, 72 = hypoproct, ventral view, 73 = epiproct and cerci, subdorsal (epiproct broadest) view, 74 = spermathecae in glycerol. (C: cercus, EP: epandrium, hy: hypoproct, PG: postgonite, S 7 + 8: sternite 7 fused with sternite 8, sscl: subepandrial sclerite, T 8: tergite 8). Scale bar: Figs 68 – 74 = 0.1 mm.