Brachycentrus (Sphinctogaster) chelatus Ross 1947

Brachycentrus (Sphinctogaster) chelatus Ross

Brachycentrus chelatus Ross, 1947:164.—Fischer, 1970:101.

Brachycentrus numerosus (Say).—Harris, Lago and Scheiring, 1982:81 [misidentification].

This species is provisionally placed in the B. lateralis (Say) subgroup because it lacks the macrochaetae on the tenth tergum. However, the apex of the clasper, especially in posteroventral aspect, is very similar in shape to that of species in the B. numerosus (Say) subgroup.

The genitalia of the male offer a number of distinctive characters. The tenth tergum is long and decumbent with the tip divided, and the clasper has a large basal area and its apex, in posteroventral aspect, shows a sharp point with a second, distinct lobe on the mesal margin.

The larvae are equally distinctive. The almost uniformly dark sclerites will separate it from most species. The roughened surface of the frontoclypeus and adjacent genae is unique in the North American species of the genus.

ADULT.—Length of forewing, 6–7 mm, 8–9 mm. Color fuscous, body and appendages fuscous, legs paler apicad; forewing fuscous, with larger and smaller cream-colored maculae. Male abdomen with seventh sternum bearing a small, posteromesal point or small, equilateral lobe.

Male Genitalia: Ninth segment lacks sternal lobe. Cercus elongate, tapering apicad in lateral aspect; in dorsal aspect cerci completely divided and well-separated mesally. Tenth tergum elongate, decumbent in lateral aspect; in dorsal aspect much longer than broad, tip divided, lateral lobes nearly twice as long as wide (in examples from western Florida, lobes are wider than long). Clasper with large basal area, apical area in lateral aspect with a small apicodorsal point; in posteroventral aspect with tip produced into a sharp point, from inner margin a pointed lobe subapically.

LARVA.—Length to 11 mm. Sclerites brown to fuscous; head brownish-fuscous, often with genae laterally and posteriorly paler than front, generally with muscle scars distinctly paler (sometimes not so); surface of frontoclypeus and genae mesad of primary setae granulate, except smooth over muscle scars; legs brownish-fuscous, mid- and hindlegs with tarsi distinctly infuscate, femora with dorsal margin sometimes with a dark band, with ventral third paler than dorsal two- thirds. Femora of mid- and hindlegs with 3 enlarged setae; apico- and basodorsal setae only slightly larger than other dorsal setae; ventral margin with a uniform fringe. Tibiae of mid- and hindlegs with a series of 3–4 basoventral setae. Two pairs of submesal, ventral setae on first abdominal segment equal in size, but slightly larger than homologous setae on second segment. Lateral fringe present from third through sixth abdominal segment, with a very few hairs on seven. Gills single, arising in dorsal, lateral, and ventral rows.

TYPE MATERIAL.—Holotype, male, INHS: “Perry, Ga., 3–17–45, P.W. Fattig,” “HOLOTYPE Brachycentrus chelatus Ross.” In alcohol, abdomen cleared, studied.

MATERIAL EXAMINED.—USA, ALABAMA, Escambia Co., Hall Creek, 4.5 mi. N Flomaton, 25 Mar 1981, Harris and O'Neil, 4 (SCHC, USNM). Escambia Co., Little Escambia Creek, Hwy. 31, 2 mi. E Flomaton, 25 Mar 1981, Harris and O'Neil, 2, 1 (SCHC, USNM). Mobile Co., Little Creek, 4 mi. SE Citronelle, 26 Mar 1981, Harris and O'Neil, 1 (SCHC). Mobile Co., Puppy Creek, Hwy. 217, 6 mi. SW Citronelle, 26 Mar 1981, Harris and O'Neil, 1 (SCHC).

FLORIDA, Okaloosa Co., Titi Creek, Rt. 211, Eglin Air Force Base, 22 Nov 1970, P. Carlson, 4 larvae (CUC). Santa Rosa Co., Coldwater Creek at Rt. S-194, 1 Feb 1969, J.B. Wallace et al., 5 larvae, 1 metamorphotype (UGA, VPI); same, but emerged 6 Feb 1969, 1 (UGA); same, but emerged 16 Feb 1969, 1 (UGA); same, but emerged 19 Feb 1969, 1 (UGA). Santa Rosa Co., Blackwater River State Forest, 10–11 Mar 1972, O.S. Flint, Jr., 1, 2. Santa Rosa Co., Blackwater River, Riley Landing, 3 mi. NW Holt, 8 Apr 1972, W.L. Peters et al., 10 larvae (CUC); same, but 9 May 1972, 1 larva (CUC); same, but 30 Oct 1971, 1 larva (CUC). Walton Co., Rocky Creek, Eglin Air Force Base, 14 Mar 1979, J. Schéiring, 12 (SCHC, USNM); same, but 20 Apr 1979, 12 (SCHC); same, but 11 May 1979, 12 (SCHC); same, but 14 Jul 1978, 12 larvae (SCHC, USNM).

GEORGIA, Perry, 17 Mar 1945, P.W. Fattig, 1 (holotype, INHS). Richmond Co., Ga. Rt. 56, 1.0 mi. S Augusta, 19 Feb 1970, Wallace and Sherberger, 4 larvae (UGA).

SOUTH CAROLINA, Aitken Co., Upper Three Runs Creek, Savannah River Plant, 29 Jan 1977, Herlong and Prichard, 1 larva (CUC); same, but 24 Feb 1978, 1 metamorphotype (CUC); same, but 26 Feb 1977, 1 larva, 1, 1 metamorphotypes (CUC); same, but 11 Mar 1977, 200 (CUC); same, but 29 Mar 1977, 2, 4 (CUC); same, but 8 Jul 1977, 100 larvae (CUC); same, but 22 Aug 1977, 100 larvae (CUC); same, but 6 Nov 1976, 1 larva; same, but 14 Dec 1976, 1 larva; same, but 19 approximately biweekly collections between 10 May 1979 and 16 Feb 1980, Kelley and McEwan, hundreds of larvae (CUC); same, but 30 Aug 1980, R.W. Holzenthal, 12 larvae (CUC); same, but 26 Sep 1981, L.E. Schimmel, 5 larvae (CUC); same, but Lower Three Runs Creek, 27 Nov 1979, Kelley and McEwan, 14 larvae (CUC). Aiken Co., Hollow Creek, near Jackson, 3 Jun 1981, S.W. Hamilton, 10 larvae (CUC); same, but 4 Sep 1976, J.W. Chapin, 10 larvae (CUC). Aiken Co., S.C. Rt. 125, NW Jackson, 1 Apr 1970, Wallace et al., 31 6 (UGA).