Hydrochasma spinosum, 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 : 26-28

8. Hydrochasma spinosum sp. n. Figs 44-48, 70

Diagnosis.

This species is distinguished from congeners by the following combination of characters: Small to moderately small shore flies, body length 1.50-2.30 mm. Head: Antenna mostly dark gray; parafacial silvery white, concolorous with facial coloration; gena comparatively high, gena-to-eye ratio 0.47-0.50. Thorax: Wing with costal vein ratio 0.73-1.76; M vein ratio 0.42-0.46. Abdomen: Tergites lacking with broad, shallow, wedge-like marking laterally, otherwise tergites 2-4 with wide medial area extensively dark slate gray (Fig. 71); tergite 5 of male light gray to silvery gray anterior margin and thin, medial stripe brownish gray. Male terminalia (Figs 44-47): Combined structures moderately elongate, in posterior view height about twice width; epandrium with dorsal arch above cerci attenuate, not connected, dorsal 2/3 somewhat angulate laterally, gradually expanded to just ventrad of midheight, thereafter narrowed on ventral third, parallel sided, broadly rounded apically, rounded margin of apex with numerous, medially oriented, relatively robust setulae (Fig. 44), other epandrial setulae oriented medially, in lateral view very narrow dorsally (Fig. 45), lateral of cerci, thereafter ventrally nearly straight with slight, anterior angulate expansion at midheight, narrowly rounded apically; cerci short, in lateral view height about twice width (Fig. 45), narrowly semicircular, not attached with epandrium, narrowed ventrally; aedeagus in lateral view (Fig. 47) elongate, with length of sclerotized portion about 10 × width, greatly enlarged ventroapically, membranous portion, shape irregular, in ventral view (Fig. 46) also showing expanded apex, spatulate, basal 2/3 narrowed, essentially parallel sided; phallapodeme in lateral view (Fig. 47) narrow, elongate, nearly straight, keel moderately weakly developed, evident at end toward attachment with hypandrium, in ventral view (Fig. 46) with hypandrial end T-shaped with crossbars forming concavity apically, thereafter toward base of aedeagus very gradually expanded to blunt apex; gonite in lateral view (Fig. 47) narrow, elongate, bar-like, obviously arched toward hypandrial end, in ventral view (Fig. 46) very narrow, shallowly arched; hypandrium in lateral view (Fig. 47) short, length about half that of phallapodeme, narrow, straight, bar-like, in ventral view (Fig. 46) widely U-shaped with very thin, pointed arms.

Type material.

The holotype male of Hydrochasma spinosum is labeled "COSTA RICA. Limón: Westfalia (4 km S; 9°54.5'N, 82°59'W; beach), 27 Jun 2001, Amnon Freidberg/USNM ENT 00189486 [plastic bar code label]/HOLOTYPE ♂ Hydrochasma spinosum 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. Fifteen paratypes (10♂, 5♀; USNM) bear the same label data as the holotype or with W. N. Mathis as the collector.

Type locality.

Costa Rica. Limón: Westfalia (4 km S; 09°54.5'N, 82°59'W; beach).

Other specimens examined.

Neotropical. COSTA RICA. Guanacaste: Bagaces Fortuna Z. P. Miravalles (10°43.1'N, 84°51.3'W; Sendero Cabro Muco; 980 m), 8-31 Jul 2002, J. D. Gutierrez (1♂, 2♀; INBio); Murciélago (10°56.5'N, 85°40.9'W), 1 Apr 1988, J. M. Hill, J. M. Mitchell, W. E. Steiner, J. M. Swearingen (2♂, 2♀; USNM); Nandayure, Estero Caletas (09°59.5'N, 85°15.2'W), 21 Mar-22 Oct 2003, D. Briceño (5♂, 1♀; INBio); Nandayure, Corozalito (10°0.1'N, 85°08.7'W), 23 Oct 2003, D. Briceño (2♀; INBio); Nandayure, Costa de Oro (09°55'N, 85°17'W; 11 m), 20 Oct 2003, D. Briceño (1♂, 1♀; INBio); Nandayure, Río Bejuco (09°50'N, 85°20'W; playa), 21 Oct 2003, D. Briceño (5♂, 1♀; INBio); Playa de Cuajiniquil (10°56.1'N, 85°42.2'W; beach), 16 Jun 2003, D. and W. N. Mathis (1♂; USNM). Limón: Guandoca, Manzanillo (09°36.8'N, 82°40.9'W), 19-25 May 2004, D. Briceño (1♂, 1♀; INBio); Talamanca, Cahuita (09°43.8'N, 82°50.7'W), 9-10 Dec 2001, E. Rojas (1♀; INBio). Puntarenas: Dominical (09°14.8'N, 83°51.4'W; 0-2 m), 11 Jun 2003, D. and W. N. Mathis (8♂, 1♀; USNM); Drake (08°41.4'N, 83°40.1'W; beach), 12 Aug 2001, D. and W.N. Mathis (1♀; USNM); Malpais (09°37.6'N, 85°09.1'W; beach), 21 Jun 2001, D. and W. N. Mathis (1♂, 2♀; USNM); Playa Jacó (09°36.5'N, 84°37.4'W; beach), 13 Jun 2003, D. and W. N. Mathis (5♂; USNM); Pochotal (09°31.4'N, 84°28.4'W; beach), 12-13 Jun 2003, D. and W. N. Mathis (8♂, 3♀; USNM); San Pedrillo (08°37.2'N, 83°44.1'W), 12-14 Aug 2001, D. and W.N. Mathis (3♂, 1♀; USNM).

Distribution

(Fig. 48). Neotropical: Costa Rica (Guanacaste, Limón, Puntarenas).

Etymology.

The species epithet, spinosum, is of Latin derivation and refers to the spinose apical portion of the epandrium.

Remarks.

As implied by its species’ name, spinosum, this species is distinguished from congeners by the numerous spine-like structures on the U-shaped, ventroapical portion of the epandrial process. The angulate, lateral epandrial margins are also distinctive.