Brachycentrus (Sphinctogaster) etowahensis Wallace 1971

Brachycentrus (Sphinctogaster) etowahensis Wallace

Brachycentrus etowahensis Wallace, 1971:313.

B. etowahensis Wallace, the third species of the B. numerosus/B. solomoni subgroup, occupies a rather restricted range around the southern end of the Appalachians. The male genitalia are similar to those of B. numerosus in lacking the subapical lobe on the mesal face of the clasper, but are very much broader apically than in either of the other species. The apex of the tenth tergum is deeply, but narrowly divided in dorsal aspect, with the two lobes not divergent.

The larvae are unique, at least within the North American species of the subgenus, in possessing more than three (usually 5–7) major setae on the femora of the mid- and hindlegs, a characteristic shared with B. echo (Ross). The legs are colored like those of B. numerosus (Say); that is, yellow with narrow, black, dorsal and ventral margins. The head is nearly black, very round, with four well-defined, very yellow, dorsal marks with a small cluster of more-or-less fused, yellow, muscle scars near the apex of the frontoclypeus.

ADULT.—Length of forewing, 7–9 mm. Color in alcohol fuscous, tibiae and tarsi paler. Male abdomen with seventh sternum bearing a large (almost twice as wide as long), posteromesal, nail-like lobe.

Male Genitalia: Ninth segment without a sternal lobe. Cercus elongate, irregular in outline; in dorsal aspect cerci divided and separated mesally, inner margin irregular. Tenth tergum elongate, barely enlarged apicad in lateral aspect; in dorsal aspect narrowly divided mesally with halves not divergent, each with a large macrochaeta. Clasper with a large basal area, apical area short, broad, almost quadrate in outline with a small pointed apex; in ventral aspect with apex developed into a mesally directed point, without a subapical, mesal lobe.

LARVA.—Length to 10 mm. Sclerites fuscous, marked with yellow; frontoclypeus anteriad to midlength constriction with an ovoid yellow mark laterally, with a yellow mark posteromesally; gena fuscous anteriad and next to frontoclypeal suture, in a band posteriad to eyes, and ventromesally, remainder yellow; legs yellow with narrow, dorsal and ventral, fuscous bands on most segments of mid- and hindlegs. Femora of mid- and hindlegs with 5–7 enlarged setae; apico- and basodorsal setae slightly enlarged over other dorsal setae; ventral fringe uniform. Tibiae of mid- and hindlegs with a basoventral row of 4–5 setae. Two pairs of submesal setae on venter of first abdominal segment of equal size, slightly larger than homologous setae of second segment. Lateral fringe present from third through seventh segments, but poorly developed on seventh. Gills single, in dorsal, lateral and ventral rows.

TYPE MATERIAL.—Holotype, male, UGA, published as “Etowah River, 5.5 miles southeast of Ball Ground, Cherokee Co., Georgia (reared); pupa coll. 12 April, 1971, adult emerged 9 May 1971, J.B. Wallace and W.R. Woodall.” Type not seen; topotypic paratypes collected 25 Apr 1971 studied.

MATERIAL EXAMINED.—USA, GEORGIA, Town Creek, Canton, 8 Oct 1950, J. Wilson, 6 larvae (INHS). Cherokee Co., Etowah River, 5.5 mi. SE Ball Ground, 25 Apr 1971, Wallace and Woodall, 3 paratypes. Cherokee Co., Etowah River at shoal ∼1 mi. below Ga 372, 23 Sep 1980, Etnier et al., many larvae (UTK).

TENNESSEE, Loudon Co., Little Tennessee River, Coytee Spring, 23 Apr 1975, Etnier et al., 22 larvae, 2 prepupae, 3 pupae (UTK, CUC). Polk Co., Hiwassee River below Patty Bridge, 5 Apr 1982, D.A. Etnier, 30 prepupae and pupae (UTK).

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* Larvae of B. fuliginosus are unknown.