Hydrochasma simplicum, 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 : 66-67

22. Hydrochasma simplicum sp. n. Figs 120-123, 131

Diagnosis.

This species is distinguished from congeners by the following combination of characters: Moderately small shore flies, body length 2.15 mm. Head: Antenna mostly dark gray; parafacial silvery white, concolorous with facial coloration; gena-to-eye ratio 0.17. Thorax: Wing with costal vein ratio 0.72-0.78; M vein ratio 0.52-0.54. Forefemur lacking a distinctive, comb-like row of stout setulae along anteroventral surface; tibiae mostly gray. Abdomen: Tergites 3-4 with wedge-shaped silvery-gray areas. Male terminalia (Figs 120-123): Combined structures generally elongate, in posterior view height more than twice width, generally sparsely setulose dorsally, setulae becoming sparse or lacking ventrally; epandrium lacking dorsal arch above cerci, in posterior view (Fig. 120) with basal 1/2-2/3 quadrate, thereafter ventrally narrowed as a taper to apex, apex with medioapical, small, U-shaped notch, in lateral view (Fig. 121) very elongate, moderately narrow with apical 3/4 straight, nearly parallel sided, basal 1/3 wider, somewhat rectangular; aedeagus in lateral view (Fig. 123) tubular, very elongate, narrow, more than 6 times longer than wide, mostly parallel sided, apical portion tapered to broad point, ventral view (Fig. 122) narrow, elongate, apical 1/8 tapered to rounded apex; phallapodeme in lateral view (Fig. 123) irregularly crescent shaped, more elongate and narrow toward base of aedeagus, keel elongate along most of phallapodeme but not extended more than width of phallapodeme, process toward hypandrium short, pointed, in ventral view (Fig. 122) somewhat I-shaped with unequal crossbars; gonite in lateral view (Fig. 123) as a very shallowly curved to sinuous, rod-like process, about equal in length to phallapodeme, in ventral view (Fig. 122) very shallowly curved to straight, slightly tapered at both apices; hypandrium in lateral view (Fig. 123) narrowly developed, parallel sided, length 3/4 that of aedeagus, in ventral view (Fig. 122) length about twice basal width, tapered from posterior to rounded, more narrowed anterior margin, deeply and narrowly notched anteromedially, posterior margin moderately deeply U-shaped, lateral margins slightly flared laterally.

Type material.

The holotype male of Hydrochasma simplicum is labeled "COSTA RICA. Prov. Limón. P[arque]. N[acional]. Barbilla, Sector Casas Negra, Orilla Río Dantas, 300m, 15DEC 2002, E. Rojas, Red de Golpe. L N 219900 598400 #704204/INB0003814812 INBIOCRI COSTA RICA [plastic bar code label]/HOLOTYPE ♂ Hydrochasma simplicum Mathis & Zatwarnicki, USNM [red]." The holotype is double mounted (minuten in a block of plastic), is in good condition (some setae of the head are misoriented or missing; abdomen removed and dissected), and is deposited in INBio. Paratypes are as follows: COSTA RICA. Cartago: Parque Nacional Barbilla, Sendero Principal, Río Dantas (09°58.5'N, 83°26.5'W; 370 m), 8 Jul 2002, E. Rojas (1♂; INBio); Río Pacuare, Sendero el Felino (09°43.6'N, 83°30.8'W; 400 m), 7 Sep 2002, E. León, E. Rojas (1♂; USNM).

Type locality.

Costa Rica. Limón: Parque Nacional Barbilla, Sector Casas Negras, (10°01.2'N, 83°26.2'W; 300 m).

Distribution

(Fig. 131). Neotropical: Costa Rica (Cartago, Limón).

Etymology.

The species epithet, simplicum, is of Latin derivation and means simple, unmixed, or single, referring to the simplistic structures of the male terminalia.

Remarks.

Among congeners, especially those of the incisum group, this species is distinguished by its simplicity, hence its species name. The epandrium, including the ventral epandrial processes, are simple, mostly straight and unadorned, as is the aedeagus, gonite, and hypandrium (Figs 120-123).