Podmosta Larvae

Stewart, Kenneth W. & Stark, Bill P., 2011, Further Descriptions Of Western North American Podmosta Larvae And Their Separation From Ostrocerca Larvae (Plecoptera: Nemouridae), Illiesia 7 (10), pp. 104-117 : 113-116

Provisional Key to North American Podmosta Larvae

Podmosta macdunnoughi (Ricker) was partially described by Ricker (1947) and Harper & Hynes (1971). Details of the cercal intercalaries are difficult to see at 50X with a dissecting light microscope, and therefore require SEM.

1 Distribution east of 90 th meridian … macdunnoughi

1’ Distribution west of 100 th meridian …..……….. 2

2 Head with distinct, light interocellar spot ( Fig. 2 ) ………………………………………....… delicatula

2’ Head without interocellar spot ( Fig.1 ) ……….. 3

3 Whorl bristles of middle and anteapical cercal segments short, at most, ca. 0.20X the length of their segment, and bearing 2- 3 intercalary hairs as seen laterally ( Fig. 44 ); widespread, Alaska south to Colorado ……………………………….. decepta

3’ Whorl bristles of middle and anteapical cercal segments long, 0.35-0.80X the length of their segment, and bearing variable number of intercalaries up to 7 ( Figs. 48, 50 ); Alaska-Yukon and south to Oregon ……………..………………. 4

4 Whorl bristles of proximal 10 cercal segments short, ca. 0.25X length of their segment ( Fig. 49 ); middle and apical cercal segments bearing 2- 4 intercalary bristles and/or fine hairs ( Fig. 50 ); Alaska and Yukon ………………………..…. weberi

4’ Whorl bristles of proximal 10 cercal segments long, about 0.67X the length of their segment ( Fig. 47 ); middle and apical cercal segments bearing 3-7 fine intercalary hairs ( Fig. 48 ); Oregon and Washington ………………………………… obscura

Figures

Figs. 2-16. Podmosta larval characters. P. delicatula. 2. head, thorax, dorsal. 3. right front leg, dorsal. 5. cercus, lateral. 9. male terminalia, dorsal. 10. male terminalia, ventral. 11. male terminalia, lateral. 12. female terminalia, dorsal. P. obscura. 4. right front leg, dorsal. 6. right cercus proximal segments, dorsal. 7. left cercus apical segments, lateral. 13. male terminalia, dorsal. 14. male terminalia, ventral. 15. male terminalia, lateral. 16. female terminalia, ventral. P. weberi. 8. right cercus, lateral (exuvium of reared male). 12a. male terminalia, ventral (exuvium of reared male).

Fig. 1. Male Podmosta obscura larva. Scale line = 2 mm.

Figs. 41-46. Podmosta and Ostrocerca abdomens and cerci. 41. P. weberi left abdominal terga 8-10. 42. O. dimicki left abdominal terga 8,9. 43. P. decepta cercomeres 9,10, lateral. 44. P. decepta cercomeres 20, 21, lateral. 45. P. delicatula proximal 7 cercomeres. 46. P. delicatula subapical cercomeres.

Figs. 47-52. Podmosta and Ostrocerca cerci. 47. P. obscura proximal cercomeres. 48. P. obscura subapical cercomeres. 49. P. weberi cercomere 10. 50. P. weberi cercomere 20. 51. O. dimicki cercomeres 10, 11, 52. O. dimicki cercomere 15.