Hydrochasma sagittarium, 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 : 103-105

34. Hydrochasma sagittarium sp. n. Figs 191-195

Diagnosis.

This species is distinguished from other congeners by the following combination of characters: Small shore flies, body length 1.35-1.75 mm. Head: Antenna mostly dark gray; parafacial silvery white, concolorous with facial coloration; gena comparatively short, gena-to-eye ratio 0.10-0.11. Thorax: Wing with costal vein ratio 0.67-0.70; M vein ratio 0.49-0.52. Forecoxa mostly yellowish orange; tergites 1-4 blackish gray dorsally. Abdomen: Tergites 1-4 broadly slate black on dorsum with sharply demarked gray lateral margin, without wedges, and gray ventral surface, tergite 5 of male gray with slate-black posterior margin. Male terminalia (Figs 191-194): Epandrium generally elongate and setulose, in posterior view (Fig. 191) with dorsal arch attenuate, not connected, dorsal 2/3-3/4 narrowly diamond shaped, widest just ventrad of cerci, thereafter ventrally tapered to arrow-shaped apex, arrow-shaped apex with length twice width, apex with narrowly incised medially, in lateral view (Fig. 192) narrowly elongate, mostly parallel sided, slightly wider at beginning of arrow-shaped apex, apex narrowly rounded; cerci elongate, length about 3 × width, medial margin shallowly sinuous (Fig. 191), dorsal apex pointed, oriented medially, narrowly hemispherical, in lateral view (Fig. 192) more robust than posterior view, length slightly more than twice width; aedeagus in lateral view (Fig. 194) relatively simple, narrowly tubular, length 11 × width, in ventral view (Fig. 193) also tubular; phallapodeme in lateral view (Fig. 194) linear, conspicuously curved, more so toward hypandrium, extended keel narrow and short, as a slight bump, in ventral view (Fig. 193) narrowly Y-shaped with arms short; gonite in lateral view (Fig. 194) narrowly elongate, bar-like, very shallowly curved, in ventral view (Fig. 193) more robustly developed, with end toward aedeagal base curved medially; hypandrium in lateral view (Fig. 194) with posterior 1/3 narrow, rod-like, anterior 2/3 with width nearly equal to that of aedeagus, in ventral view (Fig. 193) a deeply incised plate, anterior margin broadly rounded, posterior extensions curved slightly laterally.

Type material.

The holotype male of Hydrochasma sagittarium is labeled "TOBAGO. St. John: Parlatuvier (creek; 11°17.9'N, 60°35'W), 14 Jun 1993, W. N. Mathis/USNM ENT 00117966 [plastic bar code label]/HOLOTYPE ♂ Hydrochasma sagittarium 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. Nine paratypes (8♂, 1♀; USNM) bear the same label data as the holotype. Other paratypes are as follows: TRINIDAD and TOBAGO. St. George: Arima (8 km N; 10°41'N, 61°18'W), Verdant Vale, 19 Jun 1993, W. N. Mathis (8♂, 3♀; USNM). St. John: Charlotteville (2 km S; 11°19'N, 60°33'W), 10 Jun 1993, 1994, W. N. Mathis (2♂, 3♀; USNM) Speyside (1 km NW; Doctor River; 11°18'N, 60°32'W), 12-13 Jun 1993, W. N. Mathis (4♂, 5♀; USNM).

Type locality.

Trinidad and Tobago. Tobago: St. John: Parlatuvier (creek; 11°17.9'N, 60°35'W).

Other specimens examined.

Neotropical. BELIZE. Stann Creek: Sittee Point (16°48.6'N, 88°15.5'W), 28 Apr 1987, R. Faitoute, P. S. Spangler (1♂, 3♀; USNM); Twin Cays, West Bay (16°50'N, 88°06'W), 22 May 1988, W. N. Mathis (1♀; USNM); Wee Wee Cay (16°45.9'N, 88°08.6'W), 6-9 Nov 1987, D. and W. N. Mathis (3♀; USNM).

BRAZIL. Amazonas: Manaus, INPA (03°05.9'S, 59°59.1'W; 60 m), 4 May 2010, D. and W. N. Mathis (1♂, 2♀; INPA, USNM); Reserva Ducke (02°55.8'S, 59°58.5'W; 40 m), 5 May 2010, D. and W. N. Mathis (1♀; INPA, USNM). Paraná: Antonina (25°27.1'S, 48°41.1'W; beach; Ponta da Pita), 15 Feb 2010, D. and W. N. Mathis (1♂; USNM); Bocaiúva do Sul (25°16.6'S, 48°58.5'W; 770 m), 16 Feb 2010, D. and W. N. Mathis (1♂; DZUP, USNM); Curitiba, Universidade Federal do Paraná, Reserva Biológica (25°26.9'S, 49°14'W; 915 m), 9-11 Dec 2009, D. and W. N. Mathis (1♂, 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 (2♂; DZUP, USNM).

COSTA RICA. Limón: Parque Nacional Barbilla, Sector Casas Negras, Orilla Río Dantas (09°59.8'N, 83°26.2'W; 300 m), 15 Dec 2002, E. Rojas (1♂; INBio).

ECUADOR. Napo: San Francisco de Borja (0°25.4'S, 77°50.5'W; 1610 m), 17 Jan 1978, W. N. Mathis (1♂; USNM). Pastaza: Río Puyo (01°40'S, 77°55'W), R. Levi-Castillo (9♂, 11♀; USNM).

PERU. Cuzco: Paucartambo, Atalaya ( Río Alto Madre de Dios; 12°53.1'S, 71°21.6'W; 600 m), 4 Sep 1988, W. N. Mathis (3♂, 14♀; USNM).

Distribution

(Fig. 195). Neotropical: Belize (Stann Creek), Brazil (Amazonas, Paraná), Ecuador (Napo, Pastaza), Peru (Cuzco), Trinidad and Tobago.

Etymology.

The species epithet, sagittarium, is of Latin derivation and means arrow, referring to arrow-like apex of the epandrium.

Remarks.

Although similar to several species in the leucoproctum group, this species is distinguished from all others by the distinctly arrowhead-shaped ventral portion of the ventral epandrial process and the deeply V-shaped hypandrium with delicately developed arms. In addition the arched and thinly develop phallapodeme that has a small projection near its midlength is diagnostic.