Hydrochasma faciale (Williston)

Mathis, Wayne N. & Zatwarnicki, Tadeusz, 2013, A revision of the shore-fly genus Hydrochasma Hendel (Diptera, Ephydridae), ZooKeys 363, pp. 1-161 : 14-19

4. Hydrochasma faciale (Williston) Figs 18-25

Discocerina faciale Williston, 1896: 396 [West Indies. St. Vincent; LT ♂ (designated by Mathis and Edmiston 1991: 825-826), BMNH].

Hydrochasma faciale Wirth, 1968: 8 [generic combination; Neotropical catalog]. Mathis and Edmiston 1991: 825-826 [review of Williston’s St. Vincent species]. Mathis and Zatwarnicki 1995: 182 [world catalog]. Mathis 1997: 36 [review, Belize].

Hydrochasma zernyi Hendel, 1936: 103 [Brazil. Pará: Santarém; ST ♂, NMW]. Cresson 1938: 25 [review]; 1946: 141 [review]. Wirth 1968: 8 [synonymy with Hydrochasma faciale ].

Hydrochasma capax Cresson, 1938: 26; 1942: 113 [list, Arizona and California]; 1946: 141 [review]. Wirth 1965: 738 [Nearctic catalog]; 1968: 8 [synonymy with Hydrochasma faciale ]. Cole 1969: 398 [list, Western North America].

Diagnosis.

This species is distinguished from congeners by the following combination of characters: Small to moderately small shore flies, body length 1.40-2.50 mm. Head: Head subglobose, very broad ventrally, oral opening comparatively large; antennal coloration variable, entirely yellow to nearly evenly divided between yellowish and dark gray, dorsal and anterior surfaces of pedicel and basal flagellomere extensively dark gray; parafacial silvery white, concolorous with face (Figs 18-20); gena-to-eye ratio 0.25-0.28. Thorax: Mesonotum yellowish to golden brown; pleural area gray. Wing with costal vein ratio 0.71-0.75; M vein ratio 0.54-0.56. Forefemur bearing a distinctive, comb-like row of stout setulae along anteroventral surface; tibiae mostly gray; hindtibia bearing a large, spur-like seta ventroapically. Abdomen: Tergites broadly brown medially, lacking wedge-shaped, gray to silvery gray areas laterally; tergite 5 of male brown, concolorous with tergites 2-4. Male terminalia (Figs 21-24): Combined structures generally slightly elongate, in posterior view height about 1.5 × width, generally setulose, especially dorsally but also along ventral margins; epandrium with dorsal arch above cerci attenuated, not connected, in posterior view (Fig. 21) with cercal cavity forming a U, with arms of U robustly developed, ventral portion with each lateral half robustly developed, tapered to ventral apex, apex pointed, deeply and narrowly incised medially, medial incision 3 × longer than wide, widest at apex, in lateral view (Fig. 22) with ventral portion robust, apex obtusely pointed; cerci moderately long, height more than twice width, widely semi-hemispherical (Fig. 21), pointed dorsally, not attached lateroventrally or ventrally with epandrium; aedeagus in lateral view (Fig. 24) elongate, almost 4 × longer than width, tubular, shallowly curved, apex rounded, in ventral view (Fig. 23) mostly tapered from base to pointed apex, apical third more abruptly tapered; phallapodeme in lateral view (Fig. 24) triangular with extended keel skewed and pointed on portion toward attachment with hypandrium, in ventral view (Fig. 23) an elongate, moderately robust T with double crosses, arms of cross short; gonite in lateral view (Fig. 24) narrow, moderately elongate, bar-like, very shallowly curved, in ventral view (Fig. 23) shallowly curved; hypandrium in lateral view (Fig. 24) moderately elongate, sack-like, moderately wide, tapered to point posteriorly, anterior margin broadly rounded, in ventral view (Fig. 23) very broadly and robustly U-shaped, with tiny, pointed lateral extensions from base laterally.

Type material.

The lectotype male of Discocerina faciale Williston (designated by Mathis and Edmiston 1991: 825) is labeled "Co-type [circular label with a yellow border]/Windward side St. Vincent, W.I. H. H. Smith./W.Indies. 1907-66./ Discocerina facialis Will. [handwritten, two red submarginal borders]/LECTOTYPE Discocerina facialis Will. ♂ By W. N.Mathis [handwritten except for “LECTOTYPE” and “By”, black sub-border]." The lectotype is double mounted (pin in rectangular piece of cardboard), is in poor condition (right foreleg, mid legs missing), and is deposited in the BMNH. There is also one female paralectotype (BMNH). Williston, in the original description, noted "Five specimens. St. Vincent." The other syntypes (1♂, 2♀; BMNH) are apparently representatives of Hydrochasma incisum (no silvery triangular patches on dorsum of abdomen).

The lectotype male of Hydrochasma zernyi Hendel, here designated to preserve stability and make more universal the use of this name, is labeled "Unt. Amazonas [Brazil. Pará] Santarem 18. VIII 27. [18 Aug 1927] Zerny ["18. VIII" handwritten]/Hydrochas-ma Zernyi H. [handwritten]/Type [red]/LECTOTYPE ♂ Hydrochasma zernyi Hendel By Mathis & Zatwarnicki [handwritten except for “LECTOTYPE” and “By”; black sub-border]." The lectotype is double mounted (minuten in a rectangular block of foam plastic), is in good condition, and is deposited in NMW. There are also four (3♂, 1♀) paralectotypes in the NMW that bear the same locality label.

The holotype female of Hydrochasma capax Cresson is labeled "Gualan Guatemala 2-15 [handwritten] [19]05/1096/TYPE Hecamedoides CAPAX E.T. Cresson, Jr. [species name handwritten]." The holotype is double mounted (paper triangle), is in good condition (mid- and hindlegs on right side missing), and is deposited in the ANSP (6533).

Type locality.

West Indies. St. Vincent (13°10'N, 61°14'W).

Other specimens examined.

Nearctic. UNITED STATES. ARIZONA. Pima: near Kits Peak, Baboquivari Mountains (32°00N, 111°36'W), 7-8 Aug 1916 (1♀; ANSP).

CALIFORNIA. San Diego: San Diego (32°42.9'N, 117°09.4'W; lakeside), 4 Aug 1931, J. M. Aldrich (1♂; ANSP).

Neotropical. BELIZE. Stann Creek: Dangriga (16°58'N, 88°13'W), 3-4 Apr 1993, W. N. Mathis (3♂, 2♀; USNM); Twin Cays (south end of East Island; 16°49.4'N, 88°06.3'W), Mar 1988, W. N. Mathis (1♂; USNM).

BRAZIL. Paraná: Morretes (25°28'S, 48°59.1'W), 29 Aug 2000, W. N. and D. Mathis (9♂, 3♀; USNM). São Paulo: Ubatuba, Praia Puruba (23°21'S, 44°55.6'W; beach), 29 Mar 2010, D. and W. N. Mathis (9♂, 1♀; DZUP, USNM).

GUYANA. Karanambo, Rupununi River (ox bow; 03°45.1'N, 59°18.6'W), 2 Apr 1994, W. N. Mathis (1♂, 1♀; USNM); Kato, Chiung River (04°39.7'N, 59°50.0'W), 1 May 1995, W. N. Mathis (2♂; USNM); Moco-Moco (30 km E Lethem in Kanuku Mountains; 03°18.2'N, 59°39.0'W), 29 Apr 1995, W. N. Mathis (2♂; USNM); Pirara Ranch and River (03°32.1'N, 59°40.5'W), 24-25 Apr 1995, W. N. Mathis (9♂, 13♀; USNM).

TRINIDAD and TOBAGO. Tobago. St. John: Speyside (11°18'N, 60°32'W), 13-15 Jun 1993, W. N. Mathis (2♂, 2♀; USNM).

West Indies. CUBA. Pinar del Rio: Soroa (22°47.7'N, 83°W), 4-6 Dec 1994, W. N. Mathis (6♂, 12♀; USNM); Soroa (2 km E; 22°47.7'N, 83°W), 29 Apr 1983, W. N. Mathis (1♀; USNM).

DOMINICA. Cabrits Swamp (15°35'N, 61°29'W), 22-25 Mar 1965, W. W. Wirth (1♀; USNM); Layou River mouth (15°23.6'N, 61°25.5'W), 9 Jan-24 Mar 1965, W. W. Wirth (43♂, 44♀; USNM); Macoucheri (15°26.6'N, 61°27'W; seashore), 1 Feb-8 Mar 1965, W. W. Wirth (2♂, 2♀; USNM); Rosalie (15°22.3'N, 61°15.3'W), 23 Mar 1989, W. N. Mathis (2♂, 2♀; USNM).

DOMINICAN REPUBLIC. La Vega: Constanza (ca. 16 km SE; 18°50.6'N, 70°40.7'W; 1580 m), 15 May 1998, D. and W. N. Mathis (1♂; USNM); El Rio (9.5 km E; 19°0.9'N, 70°33.5'W; 980 m), 6-7 May 1995, W. N. Mathis (1♂, 1♀; USNM); Jarabacoa (1-2 km S; 19°06.9'N, 70°37'W; 520 m), 8-21 May 1995, W. N. Mathis (1♂; USNM); Rio Camu (3.5 km NW La Vega; 19°13.7'N, 70°35.2'W; 100 m), 10 May 1995, W. N. Mathis (9♂, 4♀; USNM); Salto Baiguate (near Jarabacoa; 19°05.5'N, 70°36.9'W; 570 m), 9 May 1995, W. N. Mathis (1♂; USNM). Peravia: San José Ocoa (10 km NE; 18°35'N, 70°25.6'W), 21 May 1998, D. and W. N. Mathis (1♀; USNM). Puerto Plata: Rio Camu (14 km E Puerto Plata; 19°41.9'N, 70°37.4'W), 17 May 1995, 1997, D. and W. N. Mathis (6♂, 3♀; USNM); Rio Pérez (near Imbert; 19°44.1'N, 70°50.2'W), 24 May 1998, D. and W. N. Mathis (6♂, 1♀; USNM).

GRENADA. St. George: Beauséjour Bay (12°05.5'N, 61°44.9'W), 21 Sep 1996, W. N. Mathis (1♂; USNM). St. John: Palmiste (12°08.7'N, 61°44.4'W), 21 Sep 1996, W. N. Mathis (3♂, 1♀; USNM). St. Patrick: Levera Bay (12°13.6'N, 61°36.6'W), 18 Sep 1996, W. N. Mathis (2♂; USNM).

JAMAICA. Clarendon: Grantham (18°09.3'N, 77°23.8'W; 340 m), 16 Apr 2000, W. N. Mathis (5♂; USNM). Portland: Berridale (18°06.5'N, 76°20'W), Rio Grande River, 25 Apr 2000, W. N. Mathis (6♂; USNM). St. Andrew: Mavis Bank (1.7 km E; 18°02.4'N, 77°39.5'W; 575 m), Yallahs River, 21-22 Apr-1 May 2000, W. N. Mathis (3♂, 4♀; USNM); Mavis Bank (4.3 km SE; 18°01.4'N, 76°38.1'W; 480 m); Yallahs River, 22-23 Apr 2000, W. N. Mathis (1♂; USNM). St. Thomas: Bath Fountain Spring (17°57.6'N, 76°21.3'W), 15 May 1996, D. and W. N. Mathis, H. B. Williams (3♀; USNM); Bath River, Bath (17°56.8'N, 76°21.6'W), 16 May 1996, D. and W. N. Mathis, H. B. Williams (8♂, 2♀; USNM); Hagley Gap (1 km E; 18°00.1'N, 76°36.7'W), 16 May 1996, D. and W. N. Mathis, H. B. Williams (1♂, 1♀; USNM); Mt. Lebanus (17°58.2'N, 76°32.7'W), 16 May 1996, D. and W. N. Mathis, H. B. Williams (2♂; USNM); Yallahs River (mouth; 17°53'N, 76°35.6'W), 14 May 1996, D. and W. N. Mathis, H. B. Williams (1♂, 2♀; USNM).

PUERTO RICO. Adjuntas (18°09.8'N, 66°43.2'W), 22 Sep 1995, D. and W. N. Mathis (10♂, 5♀; USNM).

ST. LUCIA. Dauphin Boguis (1.6 km S Marquis; 14°01'N, 60°55'W), 17 Jun 1991, D. and W. N. Mathis (3♂, 5♀; USNM); Micoud (13°49'N, 60°54'W), 15 Jun 1991, D. and W. N. Mathis (1♂; USNM); Soufrière (beach; 13°51'N, 60°54'W), 11-12 Jun 1991, D. and W. N. Mathis (3♂, 1♀; USNM).

ST. VINCENT. Charlotte: Colonarie (13°14.4'N, 61°06.9'W; beach), 29 Mar 1989, W. N. Mathis (2♂; USNM); Spring (13°11.1'N, 61°08.5'W), 6 Sep 1997, W. N. Mathis (2♂, 2♀; USNM). St. Andrew: Buccament Bay (near beach; 13°11'N, 61°16'W), 25-28 Mar-8 Jun 1989, 1991, D. and W. N. Mathis (20♂, 23♀; USNM); Layou (13°12'N, 61°17'W), 8 Jun 1991, D. and W. N. Mathis (2♂, 1♀; USNM). St. David: Richmond Beach (13°18.6'N, 61°14.1'W), 28 Mar 1989, W. N. Mathis (1♀; USNM). St. Patrick: Cumberland Bay (13°16'N, 61°16'W), 28 Mar-8-15 Sep 1989, 1991, 1997, A. Freidberg, D. and W. N. Mathis (20♂, 10♀; USNM); Cumberland River (3 km E Spring Village; 13°15'N, 61°14'W), 10 Jun 1991, D. and W. N. Mathis (19♂, 2♀; USNM); Wallilabou (beach; 13°15'N, 61°16'W), 27 Mar 1989, W. N. Mathis (5♂, 10♀; USNM).

Distribution

(Fig. 25). Nearctic: United States (Arizona, California). Neotropical: Belize (Stann Creek), Brazil ( Pará, Paraná, São Paulo), Guatemala, Guyana, Trinidad and Tobago, West Indies (Cuba, Dominica, Dominican Republic, Grenada, Jamaica, Puerto Rico, St. Lucia, St. Vincent).

Natural History.-This species occurs along freshwater streams and rivers or sometimes brackish water systems (where a freshwater stream or river is entering the ocean) that have sandy areas that are mostly bare of vegetation.

Remarks.

We follow Wirth (1968) in recognizing the two junior synonyms of Hydrochasma faciale , as noted in the synonymy.

Although this species is externally similar to Hydrochasma williamsae , as are structures of the male terminalia, they are distinguished from each other in details of the latter structures. The epandrium of this species, for example, is broadly rounded dorsolaterally, not angulate as in Hydrochasma williamsae , and the ventral margin in lateral view is robustly developed and broadly but unevenly rounded apically, not tapered and pointed as in Hydrochasma williamsae .