Hydrochasma denticum, 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 : 34-37

11. Hydrochasma denticum sp. n. Figs 62-69, 71

Diagnosis.

This species is distinguished from congeners by the following combination of characters: Small shore flies, body length 1.15-1.70 mm. Head: Antenna mostly dark gray; parafacial silvery white, concolorous with facial coloration (Figs 62-64); gena-to-eye ratio 0.0.19-0.21. Thorax: Wing with costal vein ratio 0.68-0.71; M vein ratio 0.54-0.56. Forecoxa whitish gray, yellowish at apices; forefemur lacking a distinctive, comb-like row of stout setulae along anteroventral surface; tibiae mostly gray. Abdomen: Tergites 2-3with wedge-shaped silvery-gray areas on slate black dorsum (Fig. 71); tergite 5 of male mostly gray with blackish posterior margin. Male terminalia (Figs 65-68): Combined structures generally moderately elongate, in posterior view height 2.25 × width, generally sparsely setulose dorsally, setulae sparse or lacking ventrally; epandrium lacking dorsal arch above cerci, in posterior view (Fig. 65) with apical 1/2-2/3 abruptly narrowed, parallel sided, apical process not wider than apical 1/2, apex with very narrow apicomedial cleft, in lateral view (Fig. 66) very elongate, narrow with basal 3/4 straight, apical 1/3 becoming slightly wider, slightly expanded, apex narrowly rounded, with paired subapical tooth-like structures on each process; aedeagus in lateral view (Fig. 68) very elongate and very narrow, mostly parallel sided, apical 1/8 expanded anteriorly and to a less degree posteriorly, apex irregularly rounded, in ventral view (Fig. 67) very narrow and elongate, apical 1/8 bulbously expanded, apex broadly V-shaped; phallapodeme in lateral view (Fig. 68) very narrow and elongate, rod-like, hypandrial end with narrowly pointed keel, aedeagal end very shallowly curved, in ventral view (Fig. 67) elongate, narrow, truncate, slightly and gradually expanded at aedeagal end, hypandrial end with 2 narrow crossbars; gonite in lateral view (Fig. 68) as a very shallowly curved, rod-like process, about equal in length to phallapodeme, in ventral view (Fig. 67) shallowly curved to straight, tapered at both apices; hypandrium in lateral view (Fig. 68) narrowly developed, anterior half narrowly angled, gradually expanded toward midlength, thereafter narrowed to parallel-sided, elongate extension, in ventral view (Fig. 67) moderately deeply and thickly V-shaped, with base of V rectangular, robustly developed, extended lateral arms thick, elongate, each narrowly cleft apically, bifurcate.

Type material.

The holotype male of Hydrochasma denticum is labeled "ECUADOR. Prt. Or[e][l]lana: RioTiputini(0°38.2'S, 76°8.9'W), 12-26 Aug 1999, W.N.Mathis, A. Baptista, M. Kotrba/USNM ENT 00117964 [plastic bar code label]/HOLOTYPE ♂ Hydrochasma denticum 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. Seventeen paratypes (15♂, 2♀; USNM) bear the same label data as the holotype.

Type locality.

Ecuador. Orellana: Río Tiputini (0°38.2'S, 76°8.9'W).

Other specimens examined.

Neotropical. BOLIVIA. El Beni: Cavinas (12°31'S, 66°49'W), Jan 1922, W. M. Mann (2♀; USNM); Huachi (14°13.8'S, 63°32.1'W), 21 Sep, W. M. Mann (13♂, 1♀; ANSP, USNM). La Paz: Guanay (15°29.8'S, 67°52.7'W), 460 m), 13 Mar 2001, W. N. Mathis (2♂; USNM).

HONDURAS. Cortés: San Pedro Sula (8 km S; 15°25.7'N, 88°01.4'W), 25-26 Sep 1995, D. and W. N. Mathis (1♂; USNM).

PERU. Madre de Dios: Río Manu, Pakitza (11°56.6'S, 71°16.9'W; 250 m), 9 Sep 1988, W. N. Mathis (10♂, 15♀; USNM).

Distribution

(Fig. 69). Neotropical: Bolivia (El Beni, La Paz), Ecuador (Orellana), Honduras ( Cortés), Peru (Madre de Dios).

Etymology.

The species epithet, denticum, is of Latin derivation and means tooth, referring to the tooth-like subapical structures toward the apex of the extended epandrium.

Remarks.

As implied by its species’ name, denticum, this species is distinguished from congeners by the paired, tooth-like structures located subapically on each of the ventral epandrial processes. In addition, the hypandrium in ventral view is V-shaped with robust, posterior arms that in turn are bifurcate apically.