Melanochaeta Bezzi, 1906

Mlynarek, Julia J. & Wheeler, Terry A., 2018, Phylogeny and revised classification of the tribe Elachipterini (Diptera: Chloropidae), Zootaxa 4471 (1), pp. 1-36 : 23-24

Melanochaeta Bezzi, 1906

( Figs 44–49 )

Pachychoeta Bezzi, 1895: 72 . Type species: Elachiptera atterima Strobl, 1880 = capreolus (Haliday, 1838) (original designation).

Melanochaeta Bezzi, 1906: 50 (replacement name for Pachychoeta Bezzi 1895 , preocc. Bigot, 1857).

Pachychaetina Hendel, 1907: 98 (unnecessary replacement name for Pachychoeta Bezzi, 1895 )

Lasiochaeta Corti, 1909: 147 . Type species: Elachiptera pubescens Thalhammer, 1898 (monotypy).

Diagnosis. Oscinellinae with round, smooth scutellum, reniform third antennal segment, slender to thick arista with heavy pubescence and two orbital bristles longer than the others.

Description. Chloropidae , Oscinellinae . Vertex rounded in lateral view ( Fig. 44 ); frontal triangle shining, bare to pollinose; frons microtomentose; cephalic chaetotaxy: long peristomal bristles, cruciate postocellar bristles, cruciate short ocellar bristles, long outer vertical bristles, interfrontal bristles long and on margin of frontal triangle, orbital bristles reclinate, 2 longer than others; eye sparsely and microscopically pubescent; gena narrow, vibrissal angle rounded, indistinct; face flat, wide, carina absent; first flagellomere reniform, higher than wide, arista longer than width of frons, slender to flat and wide, heavily pubescent ( Fig. 45 ); proboscis short, palpus short to longer.

Scutum square, as wide as long; thoracic chaetotaxy: 1 anterior, 2 posterior notopleurals (upper posterior sometimes weak), 1 postsutural supra-alar bristle, 1 dorsocentral bristle; scutellum rounded dorsally, round, wider than long ( Fig. 46 ); 1 pair apical scutellar bristles, 1 pair of lateral scutellar bristles; thoracic pleurites bare except for a row of setulae on katepisternum. Wing long, narrow, hyaline, second costal sector equal to third costal sector, distance between crossvein r-m and dm-cu 2–4 times length of dm-cu, anal angle reduced, alula small, much longer than wide; veins pale; halter white. Legs long and slender; male femoral organ present as 1–3 rows of 4–6 tubercles; small, apical ventral spur on mid tibia; hind tibial spur absent; tibial organ oval, sometimes very narrow, 0.2 to 0.25 times length of hind tibia.

Abdominal tergites setulose laterally and with sparse setae posteriorly, mostly microtomentose; sternites slender, 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 ( Fig. 47 ); surstylus simple, narrow, parallel sided ( Fig. 48 ); hypandrium closed posteriorly ( Fig. 49 ); pregonite fused with postgonite, weakly sclerotized; basiphallus elongate, weakly sclerotized; distiphallus short, membranous; phallapodeme simple; phallic guide sclerotized; cercus small, triangular, projecting posteroventrally.

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

Geographic distribution. Melanochaeta is distributed in the Palearctic, Afrotropical, Oriental and Nearctic realms, with highest species richness in the Afrotropical and Palearctic realms.

Remarks. Melanochaeta capreolus was consistently placed within the other Melanochaeta species in our analyses, and not close to the species of Oscinella treated as an outgroup. In the absence of additional supporting evidence (e.g. molecular sequence data), and because their decision was not based on explicit phylogenetic methods, Nartshuk and von Tschirnhaus’s (2012) reassignment of M. capreolus is not supported, for the time being. Therefore Melanochaeta should no be considered a synonym of Oscinella . If, with further evidence using different characters and further analyses, Melanochaeta is more closely related to Oscinella , and then the ICZN ruling (opinion 2336 (case 3576) 2014) will be in effect. Until that time, Melanochaeta is valid and Lasiochaeta is a junior synonym.

Figures

FIGURES 44–49. Melanochaeta species. 44–46. Melanochaeta capreolus. 44. Head, lateral; 45. Antenna; 46. Scutellum, dorsal; 47–49. Melanochaeta atricornis. 47. Male genitalia, posterior; 48. Male genitalia, lateral; 49. Male genitalia, ventral. Abbreviations: cer—cercus; epd—epandrium; hyp—hypandrium; sur—surstylus. Scale bars = 0.1 mm.