Hydrochasma parallelum, 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 : 61-62

20. Hydrochasma parallelum sp. n. Figs 105, 111-114

Diagnosis.

This species is distinguished from other congeners by the following combination of characters: Small to moderately small shore flies, body length 1.65-2.30 mm. Head: Antenna mostly dark gray; parafacial silvery white, concolorous with facial coloration; gena-to-eye ratio 0.17-0.18. Thorax: Wing with costal vein ratio 0.77-0.81; M vein ratio 0.47-0.51. Abdomen: Tergites with moderately distinctive, deep, gray to silvery gray wedges along lateral margin of darkened coloration; male tergite 5 gray. Male terminalia (Figs 111-114): Combined structures generally moderately elongate, in posterior view height almost 3 × width, generally moderately setulose dorsally, setulae sparse or lacking ventrally; epandrium lacking dorsal arch above cerci, in posterior view (Fig. 111) with apical 2/3 abruptly narrowed, parallel sided, apical process not wider than extended process, apex with very narrow apicomedial cleft, in lateral view (Fig. 112) elongate, narrow with basal 3/4 straight, apical 1/4 abruptly curved anteriorly, slight expanded, apex rounded; aedeagus in lateral view (Fig. 114) very elongate, narrow, mostly parallel sided, apical 1/8 curved anteriorly, apex pointed, in ventral view (Fig. 113) very narrow, elongate, apical 1/4 slightly expanded, apex narrowly rounded; phallapodeme in lateral view (Fig. 114) narrow, elongate, rod-like, hypandrial end slight expanded with a subapical, small, digitiform process, thereafter tapered to a point toward aedeagal base, in ventral view (Fig. 113) elongate, narrow, truncate at both ends, with a subapical crossbar; gonite in lateral view (Fig. 114) as a very shallow curved, rod-like process, slightly shorter in length than phallapodeme, in ventral view (Fig. 113) shallowly sinuous, tapered at both apices; hypandrium in lateral view (Fig. 114) narrowly developed, anterior half narrowly rectangular, thereafter posteriorly tapered to a point, in ventral view (Fig. 113) moderately deeply V-shaped, with base of V rectangular, robustly developed, extended lateral arms, thin, elongate, slightly oriented laterally, anterior margin truncate.

Type material.

The holotype male of Hydrochasma parallelum is labeled "TRINIDAD. St. Andr[ew].: Low[er]. Manzanilla (16km S, 10°22'N, 61°01'W)[,] 20Jun1993, WNMathis/USNM ENT 00285975 [plastic bar code label]/HOLOTYPE ♂ Hydrochasma parallelum 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. Five paratypes (1♂, 4♀; USNM) bear the same label data as the holotype.

Type locality.

Trinidad and Tobago. Trinidad. St. Andrew: Lower Manzanilla (16 km S; 10°22'N, 61°01'W).

Distribution

(Fig. 105). Neotropical: Trinidad and Tobago.

Etymology.

The species epithet, parallelum, is of Latin derivation and means parallel sided, referring to the parallel sided extensions of the epandrium.

Remarks.

Structures of the male terminalia of this species are similar to those of Hydrochasma dolabrutum but are distinguished from the latter species by having a comparatively more slender extended epandrial process (best seen in posterior view). Moreover, the hypandrium in general is thinner, more slenderly developed, and the anterior margin is truncate rather than being broadly rounded as in Hydrochasma dolabrutum .