Thinoscatella Mathis, 1979

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 : 25-26

Thinoscatella Mathis, 1979

Fig. 36

Thinoscatella Mathis 1979a: 20 (as a subgenus of Lamproscatella ; feminine). Type species: Lamproscatella lattini Mathis 1979a , original designation. – Olafsson 1991: 41 [revised status]. – Mathis and Zatwarnicki 1995: 288 [world catalog].

Diagnosis. This genus is similar to Lamproscatella Hendel but may be distinguished by the following combination of characters: small but conspicuous setae towards anterior margin of frontal vitta; posterior fronto-orbital seta inserted closer to medial vertical seta than to anterior fronto-orbital seta; wings hyaline, immaculate.

Description. Small to moderately small shore flies, body length 1.85–2.80 mm; brown to cinereous species.

Head: frons dull usually with distinct, subshiny to shiny frontal vitta; small, conspicuous setae towards anterior margin of frontal vitta; ocelli arranged as an isosceles triangle; lateroclinate fronto-orbital seta 2; posterior fronto-orbital seta inserted closer to medial vertical seta than to anterior fronto-orbital seta. Antenna short, dark; pedicel setae typical; basal flagellomere round, brown; arista macropubescent. Face conspicuously protruding, with an interfoveal, dorsal hump; facial setae conspicuous, 2–3 lateral facial setae curved laterodorsally; long ventroclinate setae along oral margin; Eye nearly round; gena medium (gena to eye ratio 0.38); a row of setulae at the ventral margin of gena, without a distinct genal seta.

Thorax: mesonotum mostly microtomentose, dull colored, unicolorous; pleural areas generally concolorous with mesonotum: 3 pair of dorsocentral bristles (1+2); acrostichal setae in 2 rows extending to scutellum, setae generally subequal to each other, small, prescutellar acrostichal absent; 2 pair of lateral scutellar setae, basal pair shorter than apical pair; Legs mostly concolorous with pleural areas, without distinct setae, color of tarsi brown. Wing immaculate, hyaline; costa relatively long, extended to vein M 1; stem of halter short, head oval, pale yellow.

Abdomen: tergites gray to brown, microtomentose, sometimes slightly darker toward margins; dorsal setae small and scattered. Male Terminalia ( Fig. 36 ): sternite 1 present; sternite 5 present, sternite 6 absent. Epandrium as a plate generally ovoid in posterior view or elongated ellipsoid, with a narrow opening below the cerci; surstyli either lacking or fused indistinguishably with ventral margin of epandrium; ejaculatory apodeme lacking; aedeagus tube-like, slender, sometimes strongly tapered at apex; gonites roughly to distinctly Y-shaped, dorsal arms flattened, without setae; phallapodeme laterally compressed, straight to slightly curved; Female Terminalia: sternite 8 divided, as 2 lateral, lunate sclerites; female cerci without prominent setae. Female ventral receptacle with a helmet-like operculum, small, not covering extended process.

Distribution. Holarctic and Oriental (Tibet) Regions.

Remarks. This genus comprises three species, and we included two, T. lattini (Mathis) and T. quadrisetosa (Becker) , in our taxon sampling. Adults prefer mud-sand beaches ( Mathis 1979a) and are found in considerable numbers on flat, sand-covered beaches with growths of blue-green algae ( Olafsson 1991). Immature stages are unknown.

In our phylogenetic analyses, the node giving rise to the species of Thinoscatella was the sister group to the nodes giving rise to Haloscatella and Lamproscatella .

Figures

Figures 24–47.Abdominal sternites and terminalia: (24)Philotelma sp.,female; (25)Philotelma sp.,male;(26)Ephydra (Ephydra) riparia, female; (27) Scatella (Scatella) stagnalis, female; (28) Scatella (Scatella) tenuicosta, female; 29, Scatella (Scatella) tenuicosta, male; (30) Scatella (Scatella) paludum, male; (31) Lamproscatella sibilans, epandrium and cerci, posterior; (32) Haloscatella arichaeta, epandrium andcerci,posterior;(33)Haloscatella karekare,epandrium and cerci,posterior;(34)Hyadina sp., aedeagus lateral;(35)Parydra aquila, aedeaguslateral;(36)Thinoscatella lattini, internal structures ofmaleterminalia (aedeagus[shaded], phallapodeme, gonite+hypandrium), lateral; (37) Diedrops steineri, aedeagus, lateral; (38)Lamproscatella sibilans, internal structures of maleterminalia (aedeagus [shaded],phallapodeme,gonite+hypandrium),ventral;(39)Lamproscatella sibilans, internal structuresof maleterminalia(aedeagus[shaded],phallapodeme,gonite+hypandrium), lateral;(40)Haloscatella arichaeta epandrium and cerci, lateral; (41) Haloscatella arichaeta, internal structures of male terminalia (aedeagus [shaded], phallapodeme, gonite+hypandrium),lateral;(42)Haloscatellakarekare,internal structures of maleterminalia (aedeagus[shaded],phallapodeme, gonite+hypandrium), ventral; (43) Haloscatella karekare, internal structures of male terminalia (aedeagus [shaded], phallapodeme, gonite+hypandrium), lateral; (44) Paracoenia bisetulosa, ventral receptacle lateral; (45) Notiocoenia paniculate, ventral receptacle lateral; (46)Scatella (Scatella) stagnalis, ventral receptacle lateral; (47)Philotelma defectum, ventral receptacle lateral.