Hydrochasma edmistoni, Mathis, Wayne N. & Zatwarnicki, Tadeusz, 2013

Mathis, Wayne N. & Zatwarnicki, Tadeusz, 2013, A revision of the shore-fly genus Hydrochasma Hendel (Diptera, Ephydridae), ZooKeys 363, pp. 1-161 : 87-89

29. Hydrochasma edmistoni sp. n. Figs 162-166

Diagnosis.

This species is distinguished from other congeners by the following combination of characters: Small shore flies, body length 1.55-1.75 mm. Head: Antenna mostly dark gray; parafacial silvery white, concolorous with facial coloration; gena-to-eye ratio 0.16-0.17. Thorax: Wing with costal vein ratio 0.67-0.69; M vein ratio 0.52-0.54. Forecoxa mostly blackish gray to gray. Abdomen: Tergites 1-4 extensively brownish black to blackish gray dorsally, lacking lateral wedges. Male terminalia (Figs 162-165): Combined structures generally moderately elongate, in posterior view height twice width, excluding cerci, generally setulose dorsally, setulae sparse or lacking ventrally; epandrium with dorsal arch above cerci interrupted, not connected, in posterior view (Fig. 162) with basal half rectangular with angles rounded, apical half narrowed, extended as abutting, narrow, almost parallel sided processes until irregularly rounded apex, rounded apex with broad, shallow triangular extension; ventral extensions of epandrium with subapical, shallowly V-shaped structure that bears setulae, in lateral view (Fig. 163) generally moderately deeply arched with curvature more evident medially, apex rounded; cerci moderately short, height nearly twice width, semi-hemispherical (Fig. 162), attached ventrally with epandrium; aedeagus in lateral view (Fig. 165) elongate, about 4 × longer than subapical width, tubular on basal half, mostly parallel sided, expanded on apical half, in ventral view (Fig. 164) almost diamond shaped with longer basal extension being parallel sided, apex rounded; phallapodeme in lateral view (Fig. 165) narrowly elongate, moderately expanded toward anterior margin, keel as a narrow, digitiform process, in ventral view (Fig. 164) an elongate T with arms moderately wide, extended vertical shaft expanded to aedeagal base, this end truncate; gonite in lateral view (Fig. 165) narrowly elongate, bar-like, very shallowly V-shaped, in ventral view (Fig. 164) narrowly elongate, slightly swollen medially; hypandrium in lateral view (Fig. 165) elongate and comparatively narrow, width less than aedeagal base, posterior margin tapered to a slightly recurved point, anterior margin truncate, in ventral view (Fig. 164) deeply V-shaped, with vertex robustly developed and extended arms narrow, elongate anterior margin bluntly rounded.

Type material.

The holotype male of Hydrochasma edmistoni is labeled "DOMINICAN REPUBLIC. Azua: near Pueblo Viejo (18°24.8'N, 70°44.7'W), 19 May 1998, D. and W. N. Mathis/USNM ENT 00087658 [plastic bar code label]/HOLOTYPE ♂ Hydrochasma edmistoni Mathis & Zatwarnicki, USNM [red]." The holotype is double mounted (minuten in a block of plastic), is in excellent condition, and is deposited in the USNM. Paratypes are as follows: DOMINICAN REPUBLIC. La Vega: Río Camu (3.5 km NW La Vega; 19°13.8'N, 70°35.2'W; 100 m), 18 May 1998, D. and W. N. Mathis (1♂; USNM).

Type locality.

Dominican Republic. Azua: near Pueblo Viejo (18°24.8'N, 70°44.7'W).

Other specimens examined.

Neotropical. West Indies. JAMAICA. St. Andrew: Mavis Bank (1.7 km E; 18°02.4'N, 77°39.5'W; 575 m), Yallahs River, 21-22 Apr-1 May 2000, W. N. Mathis (4♂, 1♀; USNM).

Distribution

(Fig. 166). Neotropical: West Indies (Dominican Republic, Jamaica).

Etymology.

The species epithet, edmistoni, is a genitive Latin patronym to honor Father James F. Edmiston, O. F. M., a former colleague in the study of shore flies and a personal friend. Jim passed away on Sunday, May 18, 2008, and is still greatly missed.

Remarks.

Although similar to congeners of the leucoproctum group, this species is readily distinguished from them by the shape of the epandrium, especially the ventral epandrial process that is parallel-sided and has a uniquely shaped apical one-fourth. Subapically, the ventral epandrial process bears a broad and shallowly V-shaped row of tiny setulae. The hypandrium is V-shaped with a moderately well-developed anterior base and a U-shaped, posteromedial, hypandrial emargination. The posterior hypandrial arms are slightly divergent and delicately developed.