Hydrochasma garvinorum Mathis & Zatwarnicki

Mathis, Wayne N. & Zatwarnicki, Tadeusz, 2013, A revision of the shore-fly genus Hydrochasma Hendel (Diptera, Ephydridae), ZooKeys 363, pp. 1-161 : 89-92

30. Hydrochasma garvinorum Mathis & Zatwarnicki Figs 167-171

Hydrochasma garvinorum Mathis & Zatwarnicki, 2010: 117 [United States. Virginia. Rappahannock: Hazel River (NW Culpeper; 38°33.8'N, 78°11.6'W, 171 m). HT ♂, USNM].

Diagnosis.

This species is distinguished from congeners by the following combination of characters: Small shore flies, body length 1.50-1.90 mm. Head: Antenna mostly dark gray, pedicel extensively yellow, basal flagellomere yellowish ventrobasally; parafacial silvery white, concolorous with facial coloration. Gena moderately high, height usually slightly higher than length of basal flagellomere; gena-to-eye ratio 0.13-0.15. Thorax: Wing hyaline; costal vein ratio 0.40-0.50; M vein ratio 0.50-0.52. Hindtibia bearing an apicoventral, black setula. Abdomen: Tergites lacking wedge-like marking laterally but tergites 2-4 with wide medial area extensively dark slate gray to black; tergite 5 slate colored, similar to coloration of medial area on tergites 1-4. Male terminalia (Figs 167-170): Combined structures generally elongate, in posterior view height nearly 3 × width; epandrium with dorsal arch thinly tapered laterally, not connected medially above cerci, epandrium in posterior view (Fig. 167) with dorsal half somewhat quadrate, bearing some setulae medially, shallowly pedunculate near mid length, ventral portion generally lacking setulae, as 2, nearly parallel-sided, elongate processes, ventral margin V shaped, deeply incised medially, in lateral view (Fig. 168) as an elongate, shallowly curved structure, widest subapically, apex pointed; cerci short, height not quite twice width (Fig. 167), not attached lateroventrally with epandrium; aedeagus in lateral view (Fig. 170) elongate, over 5 × longer than width, basal 3/4 tubular, thinly cigar-shaped, apical 1/4 membranous, expanded, in ventral view (Fig. 169) essentially parallel sided, apex pointed; phallapodeme in lateral view (Fig. 170) narrow, elongate, unevenly spatulate with widened keel end toward hypandrium, opposite end slightly tapered and curved, keel short and narrow, in ventral view (Fig. 169) narrowly T-shaped with arms short and right angled; gonite in lateral view (Fig. 170) narrow, elongate, bar-like, shallowly curved, in ventral view (Fig. 169) very shallowly curved; hypandrium in lateral view (Fig. 170) elongate, moderately shallow, anterior 2/3 parallel sided, narrowly rectangular, in ventral view (Fig. 169) rectangular with posterior margin deeply U-shaped, anterior margin broadly rounded to truncate.

Type material.

The holotype male is labeled "USA. V[IRGINI]A. Rappahannock: Hazel Riv[,](38°33.8'N, 78°11.6'W; 171m), 24 Jul 2008, Dianne & Wayne N. Mathis/USNM ENT 00117954 [plastic bar code label]/HOLOTYPE ♂ Hydrochasma garvinorum 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. Twenty-eight paratypes (25♂, 3♀; USNM) bear the same label data as the holotype. Other paratypes are as follows:

VIRGINIA. Chesterfield: Pocahontas State Park (37°23.1'N, 77°32.4'W), 11 May 2002, D. and W. N. Mathis (5♂, 2♀; USNM). Culpeper: Lake Pelham (38°27.8'N, 78°02.7'W), 28 Apr 2006, D. and W. N. Mathis (1♀; USNM). Fairfax: Dead Run (mouth; 38°58'N, 77°10.4'W), 24 Apr 2006, D. and W. N. Mathis (1♂; USNM); Dead Run (swamp; 38°57.8'N, 77°10.3'W), 4 May 2006, D. and W. N. Mathis (5♂, 8♀; USNM); Great Falls (Patowmack Canal; 39°00.1'N, 77°15.2'W), 29 Aug 2007, D. and W. N. Mathis (1♂; USNM); Turkey Run (38°57.8'N, 77°09.4'W), 4 May 2006, D. and W. N. Mathis (3♀; USNM); Turkey Run (mouth; 38°57.9'N, 77°09.4'W), 20 Apr-23 Jul 2006, 2007, 2008, D. and W. N. Mathis, H. B. Williams, T. Zatwarnicki (13♂, 12♀; USNM). Prince William: Prince William Forest Park, South Quantico Creek (38°34'N, 77°22'W), 10 Jul– 13 Aug, D. and W. N. Mathis (15♂, 5♀; USNM). Rappahannock: Hazel River (NW Culpeper; 38°33.8'N, 78°11.6'W, 171 m), 28 Jun 2008, W. N. Mathis, T. Zatwarnicki (10♂, 1♀; USNM). Spotsylvania: Rappahannock River (38°18.8'N, 77°32.5'W), 15 Apr 2006, D. and W. N. Mathis (2♂, 2♀; USNM). Stafford: Aquia Harbour (38°27.7'N, 77°23.3'W), 15 May-21 Jul 1988, 2000, D. and W. N. Mathis (13♂, 14♀; USNM); Aquia Harbour, Lions Park (38°27'N, 77°23.3'W), 10 Apr-30 May 2005, 2006, 2007, 2008, D. and W. N. Mathis (14♂, 10♀; USNM); Falmouth (38°19.2'N, 77°28.1'W; Rappahannock River; 9 m), 11 Apr-30 Jun 2007, 2008, D. and W. N. Mathis (14♂, 6♀; USNM). Independent City: Fredericksburg (Rappahannock River; 38°18.3'N, 77°27.5'W), 14 Apr 2006, D. and W. N. Mathis (1♂, 1♀; USNM); Fredericksburg (Alum Park; 38°17.4'N, 77°28.9'W), 30 Apr 2007, D. and W. N. Mathis (3♂, 5♀; USNM).

Type locality.

United States. Virginia. Rappahannock: Hazel River (NW Culpeper; 38°33.8'N, 78°11.6'W, 171 m).

Other specimens examined.

Nearctic. UNITED STATES. CALIFORNIA. Sonoma: Mesa Grande (38°28.4'N, 123°01.5'W), Jun 1908, J. P. Baumberger (1♀; ANSP).

DISTRICT OF COLUMBIA. Rock Creek, Boundary Bridge (38°59.2'N, 77°03.2'W), 18 May 2007, D. and W. N. Mathis (4♂, 6♀; USNM); Rock Creek, Milkhouse Ford (38°57.9'N, 77°02.9'W), 18 May 2007, D. and W. N. Mathis (1♂, 3♀; NPSRC, USNM).

GEORGIA. Decatur: Spring Creek (30°51.3'N, 84°35.1'W), 16-29 Jul 1912 (1♂; ANSP).

IDAHO. Bonner: Sandpoint (48°15.2'N, 116°37.5'W), 27 Aug 1918, A. L. Melander (1♀; ANSP).

MARYLAND. Prince George’s: College Park (38°58.8'N, 76°56.2'W), 5 Sep 1977, W. N. Mathis (1♀; USNM).

MASSACHUSETTS. Worcester: Athol (42°35'N, 72°13'W), 31 Jul 1953, A. L. Melander (1♀; ANSP).

MINNESOTA. Houston: La Crescent (43°49.2'N, 91°21.1'W), 16 Jun 1925, C. B. Phillip (1♀; ANSP).

NEW JERSEY. Camden: Ashland (39°51.8'N, 75°0.4'W), 13 May (1♀; ANSP).

OHIO. Lorain: Beaver Creek near Amherst (42°24'N, 82°14'W), 22 Aug 1977, B. A. Steinly (1♀; USNM).

PENNSYLVANIA. Montgomery: Lansdale (40°14.5'N, 75°17'W), 12 Jul 1908 (1♀; ANSP); Narberth (3.2 km N; 40°01'N, 75°15.6'W), 9 Sep 1915, E. T. Cresson, Jr. (1♀; ANSP).

SOUTH DAKOTA. Bon Homme: Springfield (42°51.2'N, 97°53.8'W), 26 Jun 1924 (1♀; ANSP).

TENNESSEE. Blount: Cades Cove (spring; 35°35.6'N, 83°50.5'W), 12 Jun 2008, D. and W. N. Mathis (1♂; USNM).

Distribution

(Fig. 171). Nearctic: United States (California, District of Columbia, Georgia, Idaho, Maryland, Massachusetts, Minnesota, New Jersey, Ohio, Pennsylvania, South Dakota, Tennessee, Virginia).

Etymology.

The species epithet, garvinorum, is a pleural Latin genitive patronym to honor John Robert and Melodee Garvin ( née Bodell), who guided us to the type locality on the Hazel River, which is located in the foothills of the Blue Ridge during the summer of 2008.

Remarks.

This species is similar to Hydrochasma annae but is distinguished from it by the more robustly developed ventral epandrial process in posterior and lateral views (Figs 167-168), and the rectangular shaped hypandrium that has a moderately deep, posteromedial hypandrial emargination.