Hydrochasma kaieteur, 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 : 57-59

17. Hydrochasma kaieteur sp. n. Figs 96-100

Diagnosis.

This species is distinguished from other congeners by the following combination of characters: Small shore flies, body length 1.25-1.80 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 0.65-0.67; M vein ratio 0.54-0.58. Forecoxa mostly gray to silvery gray, some yellowish coloration at ventral apex; forefemur lacking row of spine-like setulae along anteroventral surface; tibiae mostly gray; hindtibia lacking a long, spur-like seta ventroapically. Abdomen: Tergites 3-4 with moderately deep, gray to silvery gray wedges at lateral margins; tergite 5 of male mostly to entirely gray, sometimes with posterior margin darkened. Male terminalia (Figs 96-99): Epandrium generally elongate, almost 3 times longer than wide, and setulose, in posterior view (Fig. 96) with dorsal arch attenuate, not connected, dorsal 1/3 somewhat rectangular, ventral 2/3 tapered with lateral margins shallowly sinuous to a pointed ventral margin, ventromedial apex incised, narrowly V-shaped, in lateral view (Fig. 97) very narrowly developed dorsally laterad of cerci, thereafter ventrally becoming slightly wider to midlength, then becoming wider at ventral 1/3, before becoming tapered to pointed ventral margin; cerci short, length less than twice width, in posterior view (Fig. 96) hemispherical with pointed dorsal apex and truncate ventral margin, in lateral view (Fig. 97) almost evenly semicircular; aedeagus in lateral view (Fig. 99) relatively simple, narrowly tubular except for expanded, mostly membranous apex, length 6 –7× width, in ventral view (Fig. 98) tubular; phallapodeme in lateral view (Fig. 99) spatulate with width of keel equal to width of phallapodeme, keel or spatulate end at end toward hypandrium, rest of phallapodeme tapered, curved subapically toward aedeagus, in ventral view (Fig. 98) linear, with slightly and narrowly developed T-shaped extensions; gonite in lateral view (Fig. 99) bar-like, narrowly linear, sinuous, in ventral view (Fig. 98) short, somewhat shallowly zig-zag; hypandrium in lateral view (Fig. 99) robustly bar-like width about equal to aedeagus, in ventral view (Fig. 98) somewhat rectangular with broadly and deeply emarginate posterior margin and with anterior margin as 2 blunted rounded processes and a moderately deep and narrowly incised medial portion.

Type material.

The holotype male of Hydrochasma kaieteur is labeled "GUYANA. Kaieteur Fal[l]s 5°10.5'N, 59°26.9'W [,] 21-24 August 1997[,] Wayne N. Mathis/USNM ENT 00080329 [plastic bar code label]/HOLOTYPE ♂ Hydrochasma kaieteur 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. Thirty paratypes (20♂, 10♀; USNM) bear the same label data as the holotype.

Type locality.

Guyana. Kaieteur Falls (05°10.5'N, 59°26.9'W).

Other specimens examined.

Neotropical. ARGENTINA. Formosa: Ingeniero Juárez (23°54.7'S, 61°51.8'W), 2 Jan 1949, R. Golbach (1♂; USNM).

BRAZIL. Paraná: Antonina (25°28.4'S, 48°40.9'W; beach/mangal), 9 Apr 2010, D. and W. N. Mathis (3♂; DZUP, USNM); Antonina (25°27.1'S, 48°41.1'W; beach; Ponta da Pita), 15 Feb 2010, D. and W. N. Mathis (3♂; DZUP, USNM); Matinhos (N.; 25°47.4'S, 48°31.6'W; 1 m; beach/estuary), 30 Jan-9 Apr 2010, D. and W. N. Mathis (3♂; DZUP, USNM); Morretes (25°28'S, 43°59.1'W), 29 Aug 2000, D. and W. N. Mathis (14♂, 7♀; USNM); Paranaguá (Rio Itiberê; 25°31.4'S, 48°30.3'W; 3 m), 23 Jan 2010, D. and W. N. Mathis (12♂, 2♀; DZUP, USNM); Prainha (5 km S Matinhos; 25°51.2'S, 48°33.6'W; beach), 15 Nov 2010, D. and W. N. Mathis (11♂; DZUP, USNM). Santa Catarina: Barra Velha (26°38'S, 48°40.9'W; beach), 29 Apr 2010, D. and W. N. Mathis (2♂; DZUP, USNM).

GUYANA. Conservation of Ecological Interactions and Biotic Associations (CEIBA; ca. 40 km S Georgetown; 06°29.9'N, 58°13.1'W), 13-21 Apr 1994, 1995, W. N. Mathis (1♀; USNM); Karanambo (Rupununi River; 03°45.1'N, 59°18.6'W; 85m), 1-3 Dec 2010, W. N. Mathis (20♂; USNM); Karanambo, Rupununi River (ox bow; 03°45'N, 59°17.5'W; 85m), 2 Dec 2010, W. N. Mathis (1♂; USNM); Kato, Chiung River (04°39.7'N, 59°50.0'W), 1 May 1995, W. N. Mathis (8♂, 2♀; USNM) Kumo Pond (20 km S Lethem; 03°16.7'N, 59°43.5'W), 30 Apr 1995, W. N. Mathis (2♀; USNM); Kumu River and Falls (25 km SE Lethem in Kanuku Mountains; 03°15.9'N, 59°43.6'W), 28-30 Apr 1995, W. N. Mathis (2♂, 5♀; USNM); Mahaica (3 km E; 06°43.5'N, 57°56.6'W), 14 Apr 1994, W. N. Mathis (1♂, 5♀; USNM); Mahaica (06°42.8'N, 57°55.6'W), 14-22 Apr 1994, 1995, W. N. Mathis (8♂, 14; USNM); Menzies Landing (05°10.1'N, 59°29.5'W), 23 Aug 1997, W. N. Mathis (7♂, 4♀; USNM); Paramakatoi (04°42'N, 59°42.8'W), 24-25 Aug 1997, W. N. Mathis (6♂, 2♀; USNM).

Distribution

(Fig. 100). Neotropical: Argentina (Formosa), Brazil ( Paraná, Santa Catarina), Guyana.

Etymology.

The species epithet, kaieteur, is the name of the world-famous falls in Guyana where this species was collected. The name is a noun in apposition.

Remarks.

This species is distinguished from congeners, especially those of the incisum group, by the shape of structures of the male terminalia, in particular the epandrium in posterior view and the robust, V-shaped hypandrium in ventral view.