Podmosta weberi (Ricker)

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

Podmosta weberi (Ricker)

( Figs. 8, 12a , 19-22 , 27 , 32 , 36, 38 , 41 , 49, 50 )

Distribution. Alaska and Yukon Territory.

Material Examined. Alaska: Stampede Creek, Kantishna Hills of Denali National Park , 25-VII-1981 (emerged 26-VII-1981), M. Oswood and B. Brown, 1♂ reared; 27-VII-1981 (emerged 29-VII-1981) 1♂ reared; same locality, 1-VII-1984 (emerged 20-VII-1984), D. Volsen, 1♂ reared, 1♀ reared, 7♀ larvae; same locality, 22-VII-1984, D. Volsen, 5♂, 11♀, 1♀ with attached exuvium, 4 exuvia.

Characters. Body length ♂ 4.2-4.5 mm, ♀ 4.5-5.5 mm, light brown with indistinct dark mottled pattern on occiput. Antennal segments approximately 42, head capsule width 0.80-0.90mm; eyes large, head wider than pronotum. Gills absent. Mandibles with 5 or 6 apical teeth; right mandible with raised molar pad ( Figs. 19, 21 ) that grinds against the opposing depressed molar cup of left mandible ( Figs. 20, 22 ), molar cup with outer (dorsal) comb of curved teeth ( Figs. 20, 22 ). Laciniae triangular, typical of genus, palmate, with scalloped palm surface, 7-9 fingerlike apical teeth, apicodorsal comb of about 10 long, acute-pointed bristles and apicoventral comb of about 8 short, acute-pointed bristles ( Fig. 27 ). Pronotum bearing scattered short bristles and sensillae on disc surface and lacking distinct lateral fringe ( Fig. 32 ). Wingpads bearing scattered, short bristles and tuft of short bristles on anterolateral corners ( Fig. 36 ). Femora bearing scattered short bristles and hairs over dorsal surface, longer bristles apicodorsally ( Fig. 38 ). Tibiae bearing scattered short bristles ( Fig. 38 ) and few (5-7) posterior silky fringe hairs. Mesosternal Y-ridge closed anteriorly as in Stewart & Stark (2002; Fig. 9.16E ). Abdominal terga bearing macrotrichia and microtrichia scattered on intercalary surface and forming a posterior fringe ( Fig. 41 ). Sexual dimorphism evident; males with raised tergum 10 in lateral view, and developing hypoproct on sternum 9 ( Fig. 12a ). Cercal segments 22-24, cercomeres 1-10 bearing apical whorls of stout bristles, fine hairs and sensillae, bristles about 0.25 times length of their segment ( Fig. 49 ). Middle and anteapical cercomeres bearing whorl bristles 0.35- 0.60 times length of their segment, with anteapical ones longest ventrally, and with 2- 4 intercalary bristles and/or fine hairs about 0.25 times length of their segment, all as seen laterally 9 ( Fig. 50 ). Diagnostic characters: cercal setation as described ( Figs. 49, 50 ).

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).

Figs. 17-22. Podmosta mandibles. 17. P. delicatula left mandible, ventral. 18. P. obscura left mandible, ventral. 19. P. weberi right mandible, ventral. 20. P. weberi left mandible, ventral. 21. P. weberi right molar pad. 22. P. weberi left molar cup.

Figs. 23-28. Ostrocerca and Podmosta mandibles and laciniae. 23. O. dimicki right mandible, ventral. 24. O. dimicki left mandible, ventral. 25. P. decepta lacinia, ventral. 26. P. obscura lacinia, ventral. 27. P. weberi lacinia, ventral. 28. O. dimicki lacinia, galea, ventral.

Figs. 29-34. Podmosta and Ostrocerca pronota. 29. P. decepta, right disc. 30. P. delicatula, right disc. 31. P. obscura right disc. 32. P. weberi left disc. 33. O. dimicki left disc. 34. O. dimicki left anterolateral disc margin.

Figs. 35-40. Podmosta and Ostrocerca wingpads, legs, abdominal terga. 35. P. decepta right mesothoracic wingpad. 36. P. weberi left mesothoracic wingpad. 37. O. dimicki left mesothoracic wingpad. 38. P. weberi hind femur and tibia. 39. O. dimicki hind femur and tibia. 40. P. decepta left abdominal terga 8,9.

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.