Scatella (Apulvillus) Malloch 1934

Costa, Daniel N. R., Mathis, Wayne N., Marinoni, Luciane & Sepúlveda, Tatiana A., 2024, Phylogeny and taxonomy of the shore-fly tribe Scatellini (Diptera: Ephydridae: Ephydrinae), Zoologia (e 23100) 41, pp. 1-35 : 20-21

Scatella (Apulvillus) Malloch 1934

Apulvillus Malloch 1934: 197 (as a genus; masculine). Type species: Apulvillus bronneci Malloch 1934 , original designation. – Mathis 1980: 26 [revised status]. – Mathis and Zatwarnicki 1995: 262– 263 [world catalog].

Chaetoscatella Malloch 1934: 199 (as a genus; feminine). Type species: Chaetoscatella cheesmanae Malloch 1934 , monotypy. – Wirth 1948: 296 [synonymy].

Diagnosis. Specimens of Scatella (Apulvillus) can be diagnosed by the following characters: ocellar seta short, length is half of fronto-orbital seta; face with medial portion sparsely setulose; face without row of setulae near parafacial. Species of Apulvilus are similar to those of Scatella but may be distinguished by the following characters: presutural dorsocentral seta inconspicuous or absent; row of acrostichal setae not extending to scutellum; thorax setae generally small; wing hyaline, without white spots.

Description. Moderately small to moderately large shore flies, body length 2.90–4.50 mm; blackish brown to brown species.

Head: Frons dull usually with distinct, subshiny to shiny frontal vitta; ocellar seta long or short; lateroclinate fronto-orbital seta 2; medial vertical seta long or short. Antenna short, concolorous; setae of pedicel typical; basal flagellomere round; arista macropubescent. Face conspicuously protruding, with an interfoveal, dorsal hump, medium to high; facial setae small, hair-like; 1–2 lateral facial setae curved laterodorsally; small ventroclinate setae along oral margin. Eye nearly round. Gena medium to moderately high, bearing a genal seta.

Thorax: Mesonotum generally dark brown colored, microtomentose, setae generally small; dorsocentral setae usually 2 (0+2); sutural acrostichal seta long, well developed or small, same length than other acrostichal setae; scutellum flat, disc bare, bearing 2 pairs of marginal setae; basal scutellar setae smaller than apical setae; postsutural supra-alar seta much smaller than postalar seta; legs typical, usually without distinct setae; color of tarsi variable; tarsal claws conspicuously curved and puvilli present below each claw or claws near straight and pulvilli absent; stem of halter short, head oval, white or dark. Wing generally palely to slightly infuscate, without white spots.

Abdomen: Tergites dark brown, microtomentose. Male terminalia: sternites 5 and 6 absent. Epandrium and internal structures typical of Scatella ; ventral projections of epandrium not separated; phallapodeme absent; ejaculatory apodeme present, L shaped, dorsoventrally flattened. Female terminalia: typical of Scatella ; sternite 7 as a rectangular sclerite. Female ventral receptacle tubular shaped, one to five times longer than wide.

Distribution. Oceanian (Hawaii islands, French Polynesia).

Remarks. Scatella (Apulvillus) comprises seven species that are closely related to Scatella (Scatella) and are distinguished by the wing being mostly hyaline without obvious white spots. It is a heterogeneous subgenus with some species lacking pulvilli, and with some setae from the head and mesonotum being reduced. Tenorio (1980) reported that adults are generally found in freshwater streams and described the puparium of Apulvillus mauiensis ( Wirth, 1948) .