Allocapnia virginiana Frison, 1942

Stark, Bill P. & Lacey, Joe W., 2005, Larvae Of The Winter Stonefly Genus Allocapnia (Plecoptera: Capniidae) In Mississippi, Usa, Illiesia 1 (3), pp. 10-20 : 16-19

Allocapnia virginiana Frison

Allocapnia virginiana Frison (1942) . Holotype ♂, Rapidan River, Shelby , Virginia

Distribution. AL, DE, GA, LA, MS, NC, SC, VA ( Stark 2001). Mississippi, populations have been reported from Amite, Franklin, Lauderdale, Simpson and Wilkinson Counties ( Alford 1998; Stark 1979). New records are given for Lowndes, Newton and Tishomingo Counties.

Material examined. Mississippi: Lowndes Co., Mayhew Creek, Hwy. 12, 29 December 1998, 3 ♂, B. Stark. Newton Co., Tallahatta Creek , Dean Road, 9 December 2000, 8 ♂, B. Stark. Same location, 18 December 2002, 26 ♂, B. Stark, J. Lacey. Simpson Co., Mill Creek , Hwy. 472, 11 December 2002, 5 ♂, 14 larvae, B. Stark, J. Lacey. Same location, 10 January 2002, 3 ♂, B. Stark. Same location, 3 December 2002, 4 ♂, 15 larvae, B. Stark. Simpson Co., Westville Creek , Hwy. 43, 2 December 2000, 14 ♂, B. Stark. Tishomingo Co., Little Cripple Deer Creek , Hwy 957, 4 January 2000, 39 ♂, B. Stark, M. Alford. Tishomingo Co., Jourdan Creek , Hwy. 4, 3 January 2000, 2 ♂, B.Stark, M. Alford. Tishomingo Co., Pennywinkle Creek , Hwy. 191, 3 January 2000, 1 ♂, B. Stark, M. Alford .

Male genitalia. Described from scanning electron micrographs by Alford (1998). Dorsal arm of epiproct without conspicuous bend at midlength; apical half broad, flat and surface covered with pattern of fine, longitudinal grooves ( Figs. 23-24 ). Dorsal process of tergum 8 consisting of a small erect ridge near anterior margin and a larger cushion shaped structure near posterior margin.

Pre-emergent larva. Body length 6.0-7.5 mm. Body color pale brown to tan, without distinctive pattern. Abdominal sternal folds ( Figs. 25-26 ), mandibles, laciniae and labium ( Fig. 27 ) typical of genus; galea armed on apex with a few acute spines; outer margin of galea without fringe of long setae ( Fig. 28 ). Ventral aspect of labium with tufts of long setae at intervals along the margin ( Figs. 29-30 ). Developing lobe of male tergum 10 distal to cercal bases about 1.3 times as long as tergum length proximal to cercal bases ( Fig. 31 ); dorsal margin of developing male lobe straight with slight pre-apical dip; posterior margin rounded with dorsal apex extending well beyond ventral apex. Abdominal terga sparsely covered with clothing hairs and decumbent bristles; erect bristles present at posterior tergal margins and at midlength ( Fig. 32 ); longest erect bristles about half as long as tergum.

Diagnosis. Among the other species whose larvae display erect or semi-erect bristles at midlength of most abdominal terga ( A. granulata , A. rickeri , A. starki ) the larvae of A. virginiana are distinguished from A. rickeri by virtue of a straight dorsal margin of developing male tergum 10 ( Fig. 31 ), and from the others in having the posterolateral aspect of this structure slanted rather than truncate.

Figures

Figs. 23-26. Allocapnia virginiana. 23. Male terminalia. 24. Apex of epiproct. 25. Larval abdominal sterna 8-10. 26. Larval pleural folds on sterna 6-7. (DP = dorsal process, EP = epiproct)

Figs. 27-32. Allocapnia virginiana. 27. Ventral aspect of larval head. 28. Ventral aspect of left galea. 29. Ventral aspect of larval mouthparts showing labral setal tufts. 30. Labral setal tufts. 31. Lateral aspect of larval male 10th tergum and basal cercal segments. 32. Lateral aspect of abdominal terga 7-9. (ETB = erect tergal bristle, Ga = galea, Gl = glossa, Lc = lacinia, Lp = labial palp, Mp = maxillary palp, Pg = paraglossa)