Scatophila Becker, 1896

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 : 24

Scatophila Becker, 1896

Figs 19, 22

Scatophila Becker 1896: 237 (feminine). Type species: Ephydra caviceps Stenhammar 1844 , original designation. – Zatwarnicki 1987: 277–298 [checklist]. – Zatwarnicki and Mathis 1994: 351– 370 [classification, phylogeny]. – Mathis and Zatwarnicki 1995: 281–287 [world catalog].

Centromeromyia Frey 1954: 40 (feminine). Type species: Centromeromyia eremita Frey 1954 , original designation. –Zatwarnicki 1991: 329 [synonymy].

Diagnosis. Scatophila is distinguished from other genera of Scatellini mainly by the costal vein short, extended only to vein R 4+5. Other diagnostic characters, include: 1 fronto-orbital seta (some Neotropical species with 2); and crossvein r-m distinctly distal to subcostal break.

Description. Minute to moderately small shore flies, body length 0.80–2.00 mm.

Head: Frons dull usually with distinct, subshiny to shiny frontal vitta; generally, 1 fronto-orbital seta (some Neotropical species with 2). Antenna short, dark colored; pedicel setae typical; basal flagellomere round; arista almost bare, without long dorsal branches. Face projected, sometimes central portion membranous and distinctly incised or oral margin with a protruding, narrow, sometimes spine-like projection (sexual dimorphism is frequently evident in the conformation of the face); facial setae conspicuous, lateral facial setae ventrally curved, usually indistinctly from medial facial setae, inserted mostly in the middle and ventral portions of face, 4–8 setae on the oral margin. Eye nearly round. Genal seta generally present; genal height small to high. Maxillary palpus elongate, mostly dark, as an exception yellow.

Thorax ( Figs 19, 22 ): Mesonotum microtomentose, appearing with a multicolored pattern of bands and/or spots in many species; postsutural dorsocentral setae 2; acrostichal setae in 2 rows extending to scutellum, equal in length; scutellum flat, disc bare, bearing 2 posterior setae laterally, basal scutellar setae smaller than apical setae; pleurae generally gray, lighter than mesonotum; stem of halter short, head oval, white. Legs typical, usually without distinct setae (ventral row of spinulae on mid tibiae of males of some species); color of tarsi variable; tarsal claws conspicuously curved and puvilli present below each claw. Wing faintly to conspicuously infuscate with white spots distributed over most of wing, but exceptionally within cell r1; costa short, extended to vein R 4+5; crossvein r-m distinctly distal to subcostal break; wings reduced in a few species. Legs typical, usually without distinct setae (ventral row of spinulae on mid tibiae of males of some species); color of tarsi variable; tarsal claws conspicuously curved and puvilli present below each claw.

Abdomen: Tergites gray microtomentose, sometimes with lighter posterior margins, or entirely shining black; male sternite 5 present, sternite 6 absent. Male terminalia: epandrium a closed plate; cerci completely round, rarely separated anteriorly; ventral margin of epandrium straight or slightly convex to incised medially forming two lateral lobate process; gonites Y-shaped, sharply terminated, sometimes bearing setae on dorsal margin of anterior portion; hypandrium, when present, as an inverted V-shaped structure bounded with the gonites or as a more or less sinuous band; phallapodeme dorsoventrally flattened, broad on margin connected to dorsal aedeagal opening, usually with two lateral projections, rod-like, lacking a keel; aedeagus shoe-shaped in lateral view, in most species bearing narrow, un- or paired sinuous ventral process that originates from ventral side of distal aedeagal margin; ejaculatory apodeme lacking. Female Terminalia: sternite 8 divided, as 2 lateral, subquadrate sclerites, bearing a long seta on posterior margin; female cerci without prominent setae. Operculum of female ventral receptacle helmet-like, somewhat round, covering extended process.

Distribution. Widespread: Afrotropical (Saharo-Arabian), Australiasian/Oceanian, Nearctic, Neotropical (especially Andean), Oriental, Palearctic Regions.

Remarks. Scatophila comprises 50 species and is the second most speciose taxon in the tribe. The genus mostly occurs in the Nearctic and Palearctic Regions ( Mathis and Zatwarnicki 1995). Like many other taxa in the tribe, congeners of Scatophila feed on algae and bacteria ( Deonier 1974). The immature stages are known for two species: Scatophila unicornis and Scatophila iowana ( Bolwig 1940, Deonier 1974). Zatwarnicki and Mathis (1994) presented a phylogeny of the genus and proposed nine species groups. Two species have reduced wings: Scatophila gorodkovi ( Krivosheina and Ozerov 2016) and Scatophila stenoptera ( Papp 1979) . In all of the phylogenetic analyses, the species of Scatophila were recovered as a cluster, and the node giving rise to this cluster is the sister group of Limnellia . These two clades in turn are related to Philotelma .

Figures

Figures 10–23. Head, wing and legs characters: (10) Limnellia sp., head anterior; (11) Scatella (Scatella) sp., head anteri- or; (12) Scatella (Parascatella) sp., head anterior; (13) Hyadina sp., head lateral; (14) Scatella (Parascatella) pilifera, head anterior; (15) Scatella (Scatella) stagnalis, mouth parts; (16) Philotelma sp., head lateral; (17) Physemops nemorosus, head anterior; (18)Ephydra riparia, mouth parts; (19) Scatophila caviceps, wing; (20) Scatella (Scatella) stagnalis, wing; 21, Dagus rostratus, wing; (22) Scatophila mesogramma, male, mid femur posteroventral; (23) Scatella (Scatella) stagnalis, male, fore femur anteroventral.