Hydrochasma aquia Mathis & Zatwarnicki

Mathis, Wayne N. & Zatwarnicki, Tadeusz, 2013, A revision of the shore-fly genus Hydrochasma Hendel (Diptera, Ephydridae), ZooKeys 363, pp. 1-161 : 76-78

26. Hydrochasma aquia Mathis & Zatwarnicki Figs 144-148

Hydrochasma aquia Mathis & Zatwarnicki 2010: 110 [United States. Virginia. Stafford: Aquia Harbour, Lions Park (38°27'N, 77°23.3'W); HT ♂, USNM].

Diagnosis.

This species is distinguished from congeners by the following combination of characters: Small shore flies, body length 1.50-1.95 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 0.28-0.30. Thorax: Wing hyaline; costal vein ratio 0.65-0.72; M vein ratio 0.56-0.60. Hindtibia with only pale, yellowish setae apicoventrally. Abdomen: Tergites lacking wedge-like marking laterally but tergites 2-4 with narrow to moderately 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 (Fig. 144-147): Combined structures generally elongate, in posterior view (Fig. 144) height more than twice width, dorsal portion semi-rectangular, ventral portion narrowed; epandrium with dorsal arch above cerci attenuate, not connected, dorsal half more or less roundly rectangular, slightly higher than wide, thereafter ventrally tapered to narrow, almost parallel-sided processes, apex with taper more angulate, dorsal 2/3 bearing setulae, in lateral view (Fig. 145) mostly parallel sided with anterior margin with a midlength shallow prominence, dorsal half shallowly curved anteriorly, apical half parallel sided, straight, apex moderately narrowly rounded; cerci moderately short, height not quite twice width (Fig. 144), narrowly attached ventrally tenuously with epandrium; aedeagus in lateral view (Fig. 147) very elongate, sclerotized portion very narrow, with length almost 10 × or more width, anteroapical, membranous portion only slightly expanded, width not much more than lateral width of hypandrium, membranous portion with numerous cuticular spicules, in ventral view (Fig. 146) also narrow and very elongate, almost parallel sided basally, membranous apical portion becoming wider apically, apex rounded; phallapodeme in lateral view (Fig. 147) narrow, elongate, unevenly clavate toward hypandrium, keel slightly developed, apical width, including keel, slightly less than greatest aedeagal width, in ventral view (Fig. 146) with hypandrial end narrowly linear as a T, with arms of T short and curved, thereafter toward base of aedeagus bar-like, slightly expanding; gonite in lateral view (Fig. 147) very narrow, elongate, very shallowly sinuous, in ventral view (Fig. 146) narrow, bar-like with apices toward base of aedeagus shallowly curved medially; hypandrium in lateral view (Fig. 147) elongate, moderately shallow, width more or less uniform and slightly less than 1/4 length, nearly straight, in ventral view (Fig. 146) generally deeply V-shaped with posterior margin very deeply V-shaped, anterior margin moderately narrow, bluntly rounded.

Type material.

The holotype male is labeled "USA. V[IRGINI]A. Stafford: Aquia Harbour, Lions Park (38°27'N, 77°23.3'W), 21 Jul 2008, D. & W. N. Mathis/USNM ENT 00118100 [plastic bar code label]/HOLOTYPE ♂ Hydrochasma aquia 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. Sixteen paratypes (15♂, 1♀; USNM) bear the same label data as the holotype. Other paratypes are as follows:

VIRGINIA. Culpeper: Lake Pelham (38°27.8'N, 78°02.7'W), 28 Apr 2006, D. and W. N. Mathis (1♀; USNM). Fairfax: Great Falls (quarry; 38°59.1'N, 77°14.8'W; 50 m), 13 Jun 2007, D. and W. N. Mathis (3♂; USNM); Turkey Run (mouth; 38°57.9'N, 77°09.4'W), 25 May-7 Sep 2006, 2007, 2008, D. and W. N. Mathis (5♂, 1♀; USNM). Henry: Martinsville Reservoir (36°44.7'N, 79°52.2'W), 17 May 2005, D. and W. N. Mathis (1♀; USNM). Madison: Criglersville (1.6 km W; 38°28.4'N, 78°19.9'W; 185 m; Robinson River), 1 Jul 2005, D. and W. N. Mathis (1♂, 1♀; USNM). Patrick: Meadows of Dan (36°44.2'N, 80°22.9'W), 18 May 2005, D. and W. N. Mathis (2♂; USNM); Woolwine (36°47.4'N, 80°16.7'W; 300 m), 17 May 2005, D. and W. N. Mathis (1♂, 1♀; USNM). Spotsylvania: Rappahannock River (38°18.8'N, 77°32.5'W), 3 Jul 2007, D. and W. N. Mathis (1♂, 1♀; USNM). Stafford: Aquia Creek (38°29.1'N, 77°23.8'W), 6 Jun 2005, D. and W. N. Mathis (1♂; USNM); Falmouth (38°19.2'N, 77°28.1'W; Rappahannock River; 9 m), 26 May-6 Jun 2007, D. and W. N. Mathis (2♂, 2♀; USNM).

Type locality.

United States. Virginia. Stafford: Aquia Harbour, Lions Park (38°27'N, 77°23.3'W).

Other specimens examined.

Nearctic. UNITED STATES. DELAWARE. Kent: Woodland Beach (39°19.9'N, 75°28.3'W; beach), 18 May 2006, D. and W. N. Mathis (1♂; USNM).

DISTRICT OF COLUMBIA. Rock Creek, Milkhouse Ford (38°57.9'N, 77°02.9'W), 18 May 2007, D. and W. N. Mathis (1♀; USNM).

IOWA. Louisa: Oakville (42°09.8'N, 91°0.8'W), 10 Aug 1960, D. L. Deonier (12♂, 15♀; USNM).

WEST VIRGINIA. Hardy: Mathias (38°52.6'N, 78°52'W; 465 m), 13 Jul 2007, D. and W. N. Mathis (1♀; USNM); Trout Pond (38°57.4'N, 78°44.2'W; 595 m), 13 Jul 2007, D. and W. N. Mathis (1♀; USNM). 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 (1♂; USNM).

Distribution

(Fig. 148). Nearctic: United States (Delaware, District of Columbia, Iowa, Virginia, West Virginia).

Etymology.

The species epithet, aquia, is a noun in apposition and is the name for the general area, including Aquia Creek and Aquia Harbour, where the type series of this species was collected. Aquia is the transliterated name of a Native American village (Powhatan Confederacy) located near mouth of Aquia Creek in present day Stafford County, Virginia. The name, which was originally spelled phonetically as “Quiyough,” apparently means gulls, a common bird on the creek.

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 , Hydrochasma avanae , and Hydrochasma annae but can be distinguished from these species by having a hindtibia that bears only yellowish setulae ventrally near the apex, a tapered ventral epandrial process, and by having a more delicately developed hypandrium that is deeply U-shaped in ventral view (Fig. 146).