Alombus Becker, 1914

Mlynarek, Julia J. & Wheeler, Terry A., 2018, Phylogeny and revised classification of the tribe Elachipterini (Diptera: Chloropidae), Zootaxa 4471 (1), pp. 1-36 : 12-13

Alombus Becker, 1914

( Figs 11–15 ; 56 )

Alombus Becker, 1914: 129 . Type species: Alombus politus Becker, 1914 (monotypy).

Diagnosis. Very small, black Oscinellinae with wings and halteres completely absent, reduced bristling, one long posterior notopleural, very small scutellum, syntergite 1+2 large and sclerotized.

Description. Chloropidae , Oscinellinae . Vertex rounded in lateral view ( Fig. 56 ); frontal triangle shining and bare; frons bare to microtomentose; cephalic chaetotaxy: long peristomal bristles, cruciate short postocellar bristles, cruciate short ocellar bristles, long outer vertical bristles, interfrontal setulae on margin of frontal triangle, orbital bristles reclinate, of equal size; eye sparsely and microscopically pubescent; gena narrow, vibrissal angle rounded, indistinct; face flat, wide, carina absent; first flagellomere round-reniform, higher than wide, arista longer than width of frons, and slender ( Fig. 11 ); proboscis and palpus short, black.

Scutum as wide as long; thoracic chaetotaxy: 0 anterior, 1 posterior notopleural, 0 postsutural supra-alar bristle, 1 dorsocentral bristle; scutellum rounded dorsally, triangular, usually wider than long, inclined at a 45° angle with scutum ( Fig. 12 ); 1 pair long apical scutellar bristles, 0–1 pair lateral scutellar bristles almost indistinguishable. Wing and halteres absent. Legs slender; male femoral organ present as two rows of 3–5 tubercles; small, apical ventral spur on mid tibia; hind tibial spur absent; tibial organ oval, sometimes very narrow, 0.2–0.25 times length of hind tibia.

Abdominal tergites setulose laterally and with sparse setae posteriorly, mostly shining, large; sternites small, with sparse setae; male spiracles 3–5 in membrane near lateral margin of tergite.

Male postabdomen: pregenital sclerites narrow; spiracles 6 and 7 in membrane ventral to lateral margin of dorsal sclerite; epandrium rounded, usually higher than long in lateral view and wider than high in posterior view; surstylus simple, clavate or quadrate; hypandrium closed posteriorly; pregonite fused with postgonite, weakly sclerotized; basiphallus elongate, weakly sclerotized; distiphallus short, membranous; phallapodeme simple; phallic guide sclerotized; cercus small, round, projecting ventrally ( Figs 13–14 ).

Female terminalia not modified, cerci separate, cylindrical, setulose.

Geographic distribution. Species of Alombus are restricted to the Afrotropical region, at high elevations in central Africa.

Remarks. Alombus is a genus of highly modified chloropids, primarily because of the complete loss of wings. However, its monophyly and family placement have never been questioned.

Figures

FIGURES 11–15. Alombus seminitidus. 11. Antenna; 12. Scutellum, dorsal; 13. Male genitalia, posterior; 14. Male genitalia, lateral; 15. Male genitalia, ventral. Abbreviations: cer—cerci; epd—epandrium; hyp—hypandrium; sur—surstylus. Scale bars = 0.1 mm.

FIGURES 56–57. 56. Alombus seminitidus: habitus; 57. Sepsidoscinis maculipennis: habitus. Scale bars = 0.5 mm.