Gymnoclasiopa bella (Mathis) Mathis, Wayne N. & Zatwarnicki, Tadeusz, 2012

Mathis, Wayne N. & Zatwarnicki, Tadeusz, 2012, A revision of the New World species of Gymnoclasiopa Hendel (Diptera, Ephydridae), ZooKeys 248, pp. 1-69 : 15-18

Gymnoclasiopa bella (Mathis) comb. n. Figs 17-20

Ditrichophora bella Mathis 1997: 700.

Diagnosis.

This species is distinguished from congeners by the following combination of characters: Small to medium-sized shore flies, body length 1.90-3.10 mm; generally shiny black. Head: Frons of male generally moderately microtomentose to anterior margin, only small, linear patch anterolaterally and at base of setae bare of microtomentum; frons of female with small bare areas anteriorly; 1 proclinate, fronto-orbital seta, inserted just behind and laterad of reclinate seta. Antenna black; apical margin of pedicel and 1st flagellomere invested with whitish gray microtomentum; arista bearing 5 dorsal rays. Face bearing 2 lateral, facial setae, dorsal seta inserted at level of facial prominence, ventral seta inserted toward ventral margin, distance between facial setae about equal to length of basal flagellomere; face black but mostly invested with silvery white microtomentum, only ventral portion of antennal grooves, vertical stripe immediately adjacent to parafacial, and medial stripe that curves laterally ventrally bare, shiny, black; parafacial completely microtomentose, whitish gray; gena moderately short; gena-to-eye ratio 0.10-0.13. Mouthparts, including maxillary palpus, black. Thorax: Mesonotum generally sparsely microtomentose, golden brown, becoming sparser to bare laterally, through supra-alar area, thereafter laterally sparsely microtomentose, male bearing a very distinctive stripe of dense, fine, brown microtomentum extended from postpronotum through most of notopleuron, female shiny black, similar to adjacent areas; prescutellar acrostichal setae weakly developed. Wing hyaline; costal ratio 0.37-0.44; M vein ratio 0.60-0.63; halter stem blackish brown; knob yellowish to whitish yellow. Legs except tarsi black, mostly shiny, femora with some surfaces very sparsely microtomentose; tarsi yellow except apical 2 brown; forefemur unadorned with short, peglike setulae along posteroventral surface. Halter white. Abdomen: Black, generally shiny, especially laterally and ventrally. Male terminalia (Figs 17-19): Epandrium in posterior view (Fig. 17) as a broadly rounded, inverted U, dorsal portion slightly narrower than lateral arms, in lateral view wider ventrally; cercus semilunate in posterior view (Fig. 17); aedeagus in lateral view (Fig. 19) slipper-like, base deeply and unevenly incised, tapered toward apex, apex moderately narrowly rounded, in ventral view (Fig. 18) narrowly thumb-like with basal third tapered, basal margin narrowly truncate, apical 2/3 nearly parallel-sided, apex moderately widely rounded, with thin, wing-like, narrow projections sub-basally; phallapodeme in lateral view (Fig. 19) more or less triangular, in ventral view (Fig. 18) as an inverted T; ejaculatory apodeme in lateral view (Fig. 19) L-shaped; postgonite in lateral view (Fig. 19) acutely narrow basally, thereafter becoming wider than apex narrowed, digitiform, bearing 2-3 setulae along basoposterior margin and 1 setula along margin toward hypandrium; pregonite in lateral view (Fig. 19) moderately elongate, tapered, narrowed toward hypandrium, expanded toward aedeagus, aedeagal end truncate; hypandrium in ventral view (Fig. 18) wide, width nearly twice length, broadly and shallowly rounded along anterior margin with anterolateral, pointed, lateral projections, deeply incised along posterior margin medially, in lateral view (Fig. 19) arched, posterior angle acute, thereafter anteriorly becoming wider, widest before anterior margin.

Type material.

The holotype male of Ditrichophora bella Mathis is labeled "DOMINICAN RP. Monsñ. Nouel: nr. Jima, 670m, 19°01.2'N, 70°28.8'W [,] 10May1995, W.N.Mathis/HOLOTYPE Ditrichophora bella ♂ W.N.Mathis USNM [red; species name and gender handwritten]." The holotype is double mounted (minuten pin in block of plastic), is in excellent condition, and is in the USNM. The allotype and 24 paratypes (14♂, 10♀; USNM) bear the same locality label as the holotype. Other paratypes are as follows: JAMAICA. St. Andrew: Hardwar Gap (18°04.2'N, 76°44'W), 17 May 1996, D. and W. N. Mathis, H. B. Williams (1♂, 1♀; USNM). MEXICO. Chiapas: El Triunfo (49 km S Jaltenango; 1800 m), 14 May 1985, W. N. Mathis (1♂; USNM).

Type locality.

Dominican Republic. Monseñor Nouel: near Jima (19°01.2'N, 70°28.8'W; 670 m).

Distribution

(Fig. 20). Neotropical: Mexico (Chiapas), West Indies (Dominican Republic, Jamaica).

Remarks.

All specimens were collected in montane habitats that are frequently overcast if not enshrouded in a foggy mist. The specimens from the Dominican Republic were mostly collected from a pile of spoiling cabbage that had been discarded along the roadside.

This species is sexually dimorphic with males having a brown stripe of dense but fine microtomentum extended from the postpronotum to the posterior margin of the notopleuron. Females are shiny black throughout this area of the thorax, similar to portions of the mesonotum that are immediately adjacent.

Based on external characters, this species was placed initially in the genus Ditrichophora , but structures of the male terminalia indicate a closer association with Gymnoclasiopa .

This species is distinguished from congeners, especially Gymnoclasiopa chiapas , by the following combination of characters: Postpronotum and most of notopleuron of mal e densely invested with fine, brown microtomentum, contrasted sharply with generally shiny, adjacent mesonotum and anepisternum; prescutellar acrostichal setae weakly developed; frons of male generally sparsely microtomentose to anterior margin; halter white; only 1 proclinate fronto-orbital seta; and pattern of silvery white microtomentum on face (see species description).