Paracapnia disala

Stewart, Kenneth W., 2010, The Larva Of Paracapnia Disala (Jewett) (Plecoptera: Capniidae), Illiesia 6 (2), pp. 11-15 : 13-14

P. disala

larval morphology. Body small, hairy, male 4- 4.5 mm, female 5-5.5 mm. Head and pronotum with faint, darker pattern ( Fig. 1A ). Antennal segments 44-46. Lacinia palmate, with long, stout apical teeth, long dorsal and ventral combs of 12-14 long bristles, and striated palm surface devoid of hairs ( Figs. 2-3 ). Left mandible with 4 major unserrated apical teeth, inner molar pad with small, short marginal comb of about 10 teeth, and a large palmate brush of many long bristly hairs ( Figs. 6-7 ). Pronotum rectangular with complete marginal fringe of long hairs ( Fig. 1A ). Apterous (wingpads absent) ( Fig. 1A ), reflecting condition of adults ( Stark & Baumann 2004). Femora clothed with long bristly hairs, tibia clothed with hairs and with an outer fringe of long hairs ( Fig. 1B ). Abdominal segments clothed with numerous hairs, and with distinct posterior tergal hair fringe ( Fig. 1A ). Sexual dimorphism evident; male 10 th tergum with a tubular process ( Fig. 1D, E ), female 10 th tergum without a process ( Fig. 1C ). Cercal segments more than 28 (tips broken off on all available larvae), with apical circlet of bristles and no intercalary hairs or bristles ( Fig. 1F ).

Generic and species diagnoses. The generic diagnosis of a bristly (hairy) body separating Paracapnia larvae from those of the other capniid genera ( Stewart & Stark 1988, 2002) is upheld by this study of P. disala , but their mention and illustration of “a few short intercalary bristles” on the cercal segments of P. angulata was incorrect. I have reexamined their P. angulata larval material from Wythe County Virginia, and specimens from Wisconsin and West Virginia, and there are no intercalary hairs present on cercal segments, as is also the case with P. disala ( Fig. 1F ); therefore, absence of cercal intercalary hairs is the current generic interpretation for Paracapnia .

There is interesting species difference between larvae of the eastern P. angulata and western P. disala . Those of P. angulata have macropterous wingpads, and the lacinia bears a short ventral comb of 6 or 7 medium length bristles ( Figs. 4-5 ), whereas those of P. disala are apterous, with no wingpads ( Fig. 1A ), and the lacinia bears a long ventral comb of 12-14 long bristles ( Figs. 2-3 ). The mandibles of both species are similar in teeth, molar pad, and brush of long, bristly hairs in the palm ( Figs. 6-8 ). It will be interesting in future study of the larvae of Paracapnia opis and those of the three other western Paracapnia species to see if the same east-west wingpad condition/lacinial differences hold.

Figures

Fig. 1. P. disala. A. habitus, B. right front leg, dorsal, C. female terminalia, ventral, D. male terminalia, dorsal, E. male terminalia, ventral, F. male right circus, lateral (first 28 segments).

Figs. 2-5. P. disala. 2. left lacinia, ventral (715 X), 3. left lacinia, ventral closeup (1520X), P. angulata. 4. left lacinia, ventral (1000X), 5. right lacinia, ventral (1,000X).

Figs. 6-8. P. disala. 6. left mandible, ventral (525X). 7. left mandible, ventral closeup (1100X). P. angulata. 8. left mandible (500X).