Hydrochasma rictum, 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 : 21-23

6. Hydrochasma rictum sp. n. Figs 31-35

Diagnosis.

This species is distinguished from other congeners by the following combination of characters: Small to moderately small shore flies, body length 1.55-2.00 mm. Head: Antenna mostly dark gray; parafacial silvery white, concolorous with facial coloration; gena-to-eye ratio 0.27-0.30. Thorax: Wing with costal vein ratio 0.62-0.65; M vein ratio 0.57-0.60. Forefemur with comb-like row of distinct, short, stout setulae along apical half of posteroventral margin; hindtibia bearing a short seta, length subequal to width at same level. Abdomen: Tergites broadly dark gray medially, lacking wedge-shaped, gray to silvery gray areas laterally; tergite 5 of male mostly gray but with vague, slate gray medial stripe. Male terminalia (Figs 31-34): Combined structures generally moderately elongate, in posterior view height less than twice width (1.85 ×), generally setulose on cerci, setulae sparse or minute ventrally; epandrium with dorsal arch above cerci not interrupted, narrowly connected, in posterior view (Fig. 31) with basal 1/2 somewhat ovate, apical 1/2 moderately narrowed, extended as 2 separate, moderately narrow, almost parallel sided processes with a deep, narrow gap between processes, lateral margins sinuous, each process narrowly rounded apically, in lateral view (Fig. 32) generally narrowly triangular on ventral 2/3, tapered, straight, widest just ventrad of cercus, apical third tapered, straight, apex narrowly rounded, bearing minute setulae; aedeagus in lateral view (Fig. 34) simple, straight, tubular, in ventral view (Fig. 33) mostly parallel sided on basal 2/3-3/4, apical 1/4 tapered to bluntly rounded apex; phallapodeme in lateral view (Fig. 34) oriented perpendicular to aedeagus, robustly elongate, keel evident as an extension on portion toward hypandrium, portion toward aedeagal base tapered, in ventral view (Fig. 33) pedunculate with double T with arms short and thin, perpendicular; gonite apparently lacking; hypandrium in lateral view (Fig. 34) elongate, comparatively narrow, deeply hook-like, anterior margin narrowly rounded, extension narrow, parallel sided, elongate, in ventral view (Fig. 33) more or less rectangular, with deeply incised posterolateral, short, narrow projections, posterior extensions robust, slightly flared posterolaterally, with deep pocket between, forming a U-shaped posterior margin.

Type material.

The holotype male of Hydrochasma rictum is labeled "HONDURAS. Cortés:San Pedro Sula (8 km S) 15°25.7'N, 88°01.4'W [,] 25-26 September1995[,] Dianne & W.N.Mathis/USNM ENT 00138958 [plastic bar code label]/HOLOTYPE ♂ Hydrochasma rictum Mathis & Zatwarnicki, USNM [red]." The holotype is double mounted (minuten in a block of plastic), is in good condition (abdomen and hindlegs removed, abdomen dissected, parts in an attached microvial), and is deposited in the USNM. A female paratype bears the same label data as the holotype.

Type locality.

Honduras. Cortés: San Pedro Sula (8 km S; 15°25.7'N, 88°01.4'W).

Other specimens examined.

Neotropical. COSTA RICA. Guanacaste: Playa Puerto Soley (11°02.5'N, 85°40.1'W; beach), 16 Jun 2003, D. and W. N. Mathis (1♂, 1♀; USNM). Limón: R. V. S. Gandoca-Manzanillo, desembocadura de Laguna Gandoca (09°35.4'N, 82°35.8'W), 18 May 2004, D. Briceño (1♂; INBIO).

Distribution

(Fig. 35). Neotropical: Costa Rica (Guanacaste, Limon), Honduras ( Cortés).

Etymology.

The species epithet, rictum, is of Latin derivation and means open mouth, referring to the large, open mouth of this species.

Remarks.

Structures of the male terminalia of this species are similar to those of Hydrochasma digitatum but are distinguished from that species in having more robustly developed ventral epandrial processes that are moderately angulate laterally in posterior view. Moreover, the hypandrium of this species in ventral view is much more robustly developed with a broad, bluntly rounded anterior margin.