Hydrochasma avanae Mathis & Zatwarnicki

Mathis, Wayne N. & Zatwarnicki, Tadeusz, 2013, A revision of the shore-fly genus Hydrochasma Hendel (Diptera, Ephydridae), ZooKeys 363, pp. 1-161 : 79-82

27. Hydrochasma avanae Mathis & Zatwarnicki Figs 149-153

Hydrochasma avanae Mathis and Zatwarnicki 2010: 113 [United States. Utah. Grand: Swasey Beach (15.3 km N Green River; 39°07'N, 110°06.6'W; Green River; 1255 m); HT ♂, USNM].

Diagnosis.

This species is distinguished from congeners by the following combination of characters: Small shore flies, body length 1.30-1.85 mm. Head: Antenna mostly dark gray; parafacial silvery white, concolorous with facial coloration. Gena moderately high, height usually slightly higher than length of basal flagellomere; gena-to-eye ratio 0.71-0.73. Thorax: Wing hyaline; costal vein ratio 0.66-0.82; M vein ratio 0.45-0.50. Hindtibia bearing an apical black seta ventrally. Abdomen: Tergites lacking wedge-like marking laterally but tergites 2-4 with wide medial area extensively dark slate gray to black; tergite 5 light gray to silvery gray with undifferentiated posterior margin, uniformly colored; medial coloration on tergites 1-4 narrow, sometimes only a stripe, slightly darker than color of lateral margins. Male terminalia (Figs 149-152): Combined structures generally elongate, in posterior view (Fig. 149) height about 2.5 × width; epandrium with dorsal arch above cerci attenuate, not connected, dorsal 1/3-1/2 somewhat quadrate with angles rounded, ventral portion as 2 digitiform, thick, parallel lobes that connect subapically for a short distance, ventral margin moderately narrowly rounded with deep, very narrow, apical incision medially, dorsal half bearing setulae, in lateral view (Fig. 150) mostly parallel sided with anterior shallowly sinuous, apical 1/3 tapered to sharply rounded apex; cerci short, in lateral view height about twice width (Fig. 150), narrowly semicircular, not attached with epandrium; aedeagus in lateral view (Fig. 152) elongate, with length of sclerotized portion about 5 × width, with greatly enlarged apical and ventral, membranous portion, shape in lateral view (Fig. 152) triangular, with apex broad and shallowly arched, thereafter toward base tapered to narrow, bluntly rounded margin, membrane bearing sub-basally numerous scale-like spicules, in ventral view (Fig. 151) also showing expanded apex, basal 1/3 narrowed, thereafter with middle portion ballooning out to more than twice basal width, apical 1/3 greatly expanded, broadly obovate; phallapodeme in lateral view (Fig. 152) narrow, elongate, evenly shallowly arched, keel weakly developed, barely evident at end toward attachment with hypandrium, in ventral view (Fig. 151) with hypandrial end narrowly T-shaped, thereafter toward base of aedeagus gradually expanded to blunt apex; gonite in lateral view (Fig. 152) narrow, elongate, bar-like with slightly curvature, in ventral view (Fig. 151) moderately broad but with apices narrowed, especially end toward hypandrium; hypandrium in lateral view (Fig. 152) elongate, moderately shallow, width slightly more than 1/4 length, very slightly angulate, in ventral view (Fig. 151) generally V-shaped with posterior margin deeply U-shaped, anterior margin moderately narrowly rounded.

Type material.

The holotype male is labeled "USA. UT[AH]. Grand: Green River (15.3 km N; 39°7'N, 110°6.6'W; 1255 m), 15 Aug 2008,D.&W.N.Mathis/USNM ENT 00118101 [plastic bar code label]/HOLOTYPE ♂ Hydrochasma avanae W. Mathis & T. Zatwarnicki USNM [red]." The holotype is double mounted (minuten in a block of plastic), is in excellent condition, and is deposited in the USNM. Forty-one paratypes (32♂, 9♀; USNM) bear the same label data as the holotype. Other paratypes are as follows: UTAH. Emery: Green River (3 km N; 38°59'N, 110°09'W), 5 Aug 1992, D. and W. N. Mathis (7♂, 4♀; USNM); Green River (Green River; 38°59.6'N, 110°08.5'W; 1240 m), 31 Jul 2007, D. and W. N. Mathis (6♂, 1♀; USNM); San Rafael River (22.5 km SW Green River; 38°55.7'N, 110°24.5'W; 1270 m), 31 Jul 2007, D. and W. N. Mathis (1♀; USNM). Grand: Crystal Geyser (14.5 km SE Green River; 38°56.3'N, 110°08.1'W), 15 Aug 2008, D. and W. N. Mathis (27♂, 1♀; USNM); Swasey Beach (15.3 km N Green River; 39°07'N, 110°06.6'W; Green River; 1255 m), 29 May-30 Jul 2007, 2008, D. and W. N. Mathis (7♂, 1♀; USNM); Thompson Spring (8.9 km N Thompson Springs; 39°02.3'N, 109°43.4'W; 1740 m), 1-16 Aug 2007, 2008, D. and W. N. Mathis (9♂, 4♀; USNM).

Type locality.

United States. Utah. Grand: Swasey Beach (15.3 km N Green River; 39°07'N, 110°06.6'W; Green River; 1255 m).

Other specimens examined.

Nearctic. UNITED STATES. ARIZONA. Mojave: Littlefield (36°53.1'N, 113°55.8'W), 1 May 2002, D. and W. N. Mathis (4♂, 4♀; USNM).

CALIFORNIA. San Bernardino: Afton (35°02.3'N, 116°22.9'W), 28 Apr 2002, D. and W. N. Mathis (1♀; USNM).

GEORGIA. Floyd: Lavender (34°17.5'N, 85°20.5'W), 23 Aug 1910, J. C. Bradley (1♂; ANSP). Tift: Tifton (31°27'N, 83°30.5'W), 6 Sep-Oct 1896 (1♂, 2♀; ANSP).

ILLINOIS. Cook: Chicago (41°53'N, 87°37.9'W) (1♂, 1♀; ANSP).

INDIANA. Tippecanoe: Lafayette (40°25'N, 86°52.5'W), 24 May-5 Sep 1916, E. W. Stafford (2♂; ANSP).

MICHIGAN. Kalamazoo: Kalamazoo (42°17.5'N, 85°35.2'W), 10 May 1936, C. W. Sabrosky (1♂; ANSP).

NEVADA. Clark: Las Vegas Wash (36°05.4'N, 114°58.7'W), 11 Apr 2005, D. and W. N. Mathis (2♂; USNM).

NEW MEXICO. Catron: Gila River (33°13.6'N, 106°15.1'W; 1750 m), 15 Aug 2007, D. and W. N. Mathis (4♂; USNM). Chaves: Roswell (9 km E; Pecos River; 33°23.8'N, 104°24'W; 1060 m), 10 Aug 2007, D. and W. N. Mathis (7♂, 3♀; USNM). Grant: Bill Evans Lake (32°52.1'N, 108°34.5'W; 1416 m), 14 Aug 2007, D. and W. N. Mathis (1♂; USNM); Mimbres River (NM Hwy. 61 & Royal John Mine Road; 32°43.8'N, 107°52'W; 1665 m), 13-22 Aug 2007, 2009, D. and W. N. Mathis, T. Zatwarnicki (4♂, 4♀; USNM). Lincoln: Capitan (3.2 km E; Salado Creek; 33°32.6'N, 105°32.3'W; 1890 m), 10 Aug 2007, D. and W. N. Mathis (11♂; USNM). Otero: Alamagordo (32°54'N, 105°57.6'W), 6-12 May 1902 (1♂, 1♀; ANSP). Valencia: Río Puerco (34°47.8'N, 106°59.5'W; 1575 m), 9 Aug 2007, D. and W. N. Mathis (4♂, 3♀; USNM).

OKLAHOMA. Pontotoc: Ada (34°46.5'N, 96°40.7'W), 18 Jul 1937, Standish-Kaiser (1♂; ANSP).

TENNESSEE. Shelby: Meeman Shelby State Park (Mississippi River; 35°22.2'N, 90°04.5'W; 73 m), 10 Jun 2004, W. N. Mathis (8♂, 4♀; USNM).

TEXAS. Augustine: Rayburn Park (31°04'N, 95°05'W), 15 May 1993, D. and W. N. Mathis (1♀; USNM). Fort Bend: Sugar Land (29°37.2'N, 95°38.1'W), 11 Jul 1933, R. Nabors, C. W. Sabrosky (1♂; ANSP). Hidalgo: Bentsen, Rio Grande Valley State Park (26°10.4'N, 98°23'W), 30- Nov-2 Dec 1978, E. E. Gris sell, A. S. Menke (1♀; USNM). Jim Wells: Mathis (7.5 km S; Nueces River; 28°02.2'N, 97°52.2'W; 15 m), 6 Jun 2004, W. N. Mathis (4♂, 1♀; USNM). Kimble: Junction (South Llano River; 30°29.6'N, 99°45.1'W; 510 m), 4 Jun 2004, W. N. Mathis (1♀; USNM). Travis: Austin (Zilker Park; 30°15.8'N, 97°46.3'W), 2 Jun 2004, W. N. Mathis (2♂, 1♀; USNM).

UTAH. Garfield: Willow Tank, Hurricane Wash (37°23.2'N, 111°08'W), 22 May 2001, D. and W. N. Mathis (5♂, 1♀; USNM). Kane: Drip Tank Canyon (37°19.4'N, 111°31.8'W), 15 May 2001, D. and W. N. Mathis (2♂; USNM); Kanab (6.5 km N; 37°08.7'N, 112°32.4'W), 14 May 2001, D. and W. N. Mathis (1♀; USNM). San Juan: Blanding (Reservoir 4; 37°39.9'N, 109°29.7'W; 1975 m), 20 Aug 2013, D. and W. N. Mathis (7♂, 5♀; USNM); Blanding, Recapture Reservoir (37°39.9'N, 109°26.5'W; 1840 m), 23 Jul 2013, D. and W. N. Mathis (7♂, 4♀; USNM); Johnson Creek meadow (22 km N Blanding: 37°47.5'N, 109°30.5'W; 2384 m), 20 Aug 2013, D. and W. N. Mathis (1♀; USNM).

VIRGINIA. Essex: Tappahannock (37°55.8'N, 76°51.4'W; Rappahannock River), 18 Sep 2004, D. and W. N. Mathis (1♂; USNM). Fairfax: Great Falls (Patowmack Canal; 39°00.1'N, 77°15.2'W), 3 Oct 2006, D. and W. N. Mathis (1♂; USNM); Turkey Run (mouth; 38°57.9'N, 77°09.4'W), 10 Jul-7 Sep 2006, 2007, 2008, D. and W. N. Mathis, H. B. Williams (9♂, 3♀; USNM). Patrick: Meadows of Dan (36°44.2'N, 80°22.9'W), 18 May 2005, D. and W. N. Mathis (2♀; USNM). Stafford: Aquia Harbour, Lions Park (38°27'N, 77°23.3'W), 21 Jul-4 Sep 2006, 2008, D. and W. N. Mathis (5♂; USNM); Aquia Landing (38°23.2'N, 77°19'W), 7 May 2005, D. and W. N. Mathis (2♂, 1♀; USNM); Falmouth (38°19.2'N, 77°28.1'W; Rappahannock River; 9 m), 26 May-30 Jun 2007, D. and W. N. Mathis (4♂; USNM).

WASHINGTON. Franklin: Columbia River N of Pasco (46°21.5'N, 119°15.5'W), 29 Jul 1998, W. N. Mathis (6♂; USNM); Lake Kahlotus (46°39'N, 118°32'W), 25 Jul 1992, D. and W. N. Mathis (1♀; USNM); Levey (46°05'N, 118°52'W; Snake River), 27 Jul 1992, D. and W. N. Mathis (27♂, 8♀; USNM); Ringold (NW Pasco; 46°30.4'N, 119°15.3'W; Columbia River), 30 Jul 1998, D. and W. N. Mathis (2♂; USNM); Ringold (4.8 km N; 46°30.9'N, 119°15.3'W), Columbia River, 2 Jul 1988, D. and W. N. Mathis (1♂, 1♀; USNM); Snake River, Levey Landing (46°05'N, 118°52'W), 27 Jul 1992, D. and W. N. Mathis (29♂, 7♀; USNM). Klickitat: Glenn Wood, Klickitat River (45°41.8'N, 121°17.5'W), 17 Jun 1917, A. L. Melander (1♀; ANSP). Whitman: Pullman (3.2 km NW; 46°44'N, 117°10.9'W), 11 Jul 1988, D. and W. N. Mathis (1♂; USNM).

WEST VIRGINIA. Mercer: Ceres (Kee Reservoir; 37°18.4'N, 81°10.4'W; 757 m), 24 Sep 2007, D. and W. N. Mathis (2♂; USNM). Summers: Hinton (37°41.8'N, 80°53'W; New River; 427 m), 26 Sep 2007, D. and W. N. Mathis (2♂, 2♀; USNM). Wyoming: R. D. Bailey Lake (37°35.7'N, 81°46.8'W; 324 m), 25 Sep 2007, D. and W. N. Mathis (1♂, 1♀; USNM).

Distribution

(Fig. 153). Nearctic: United States (Arizona, California, Georgia, Illinois, Indiana, Michigan, Nevada, New Mexico, Oklahoma, Tennessee, Texas, Utah, Virginia, Washington, West Virginia).

Etymology.

The species epithet, avanae, is a feminine genitive patronym to recognize Ms. Avan Thayn who guided us to the type locality.

Remarks.

This is a widespread species that is relatively common in the Nearctic Region. Externally, this species is very similar and evidently closely related to Hydrochasma andeum and Hydrochasma annae but can be distinguished from either of these two species by having a hindtibia that bears a black setula ventrally near the apex, a nearly parallel-sided ventral epandrial process, and by having a more robustly developed hypandrium, especially the anterior two-thirds (Fig. 151). In addition, the apical portion of the aedeagus is frequently greatly inflated (best seen in lateral view; Fig. 152)