Podmosta decepta (Frison)

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 : 107

Podmosta decepta (Frison)

( Figs. 8a , 25 , 29 , 35, 40 , 43, 44 )

Distribution. Widespread. Rocky Mountains and Pacific Northwest (Colorado-Utah and northwestward to Alaska).

Material examined. Colorado: Grand Co., Tonahata Creek, Big Meadows of Rocky Mountain National Park, 5-VII-1988, B.C. Kondratieff, 12♂ 14♀, 1♀ larva. Oregon: Union Co. Whiskey Creek, approximately 32 km southwest of LaGrande, 18-VI-1976, O. Dunster, 3♀ larvae. Montana: Gallatin Co. stream crossing Forest Service Road 3163 just upstream from Hyalite Youth Camp, 6-VI-1997, D.E. Ruiter, 9♂, 4♀, 3♀ larvae; Missoula Co., North Fork Elk Creek, 5-III- 1969, M. Miner, 2 vials adults, 1♂ larva, 1♀ larva (described by Stewart & Stark 1988, 2002; reexamined larvae in poor condition from manipulation for drawings and SEM of mouthparts).

Characters. Body length 3.6-5.0 mm, light brown above with indistinct mottled darker pattern on occiput and light mesal stripe on thorax ( Stewart & Stark 2002 Figs. 9.15, 9.16A ). Antennal segments 36- 38, head capsule width 0.81-0.90 mm; eyes large, head wider than pronotum. Gills absent. Mandibles with 5 or 6 apical teeth; right mandible with raised molar pad that grinds against opposing depressed molar cup of left mandible as in “mortar- pestle” action, molar cup with outer (dorsal) comb of curved teeth (similar to P. weberi , Figs. 21, 22 ). Lacinia triangular, palmate, with scalloped palm surface, 7 or 8 fingerlike apical teeth, apicodorsal comb of about 10 long, acute-pointed bristles and apicoventral comb of fewer short, acute-pointed bristles ( Fig. 25 ). Pronotum bearing scattered short bristles and sensillae over surface and lacking a distinct lateral fringe ( Fig. 29 ). Mesothoracic wingpads bearing scattered short bristles over surface and tuft of short bristles on anterolateral corners ( Fig. 35 ). Femora bearing scattered short bristles and hairs over dorsal surface, longer bristles apicodorsally (similar to P. weberi Fig. 38 , and Stewart & Stark 2002 Fig. 9.16D ). Tibiae bearing scattered short bristles and few (5 or 6) posterior silky fringe hairs ( Fig.38 and Stewart & Stark 2002, Fig. 9.16D ). Mesosternal Y-ridge faint, closed anteriorly by ridge forming rectangular area ( Stewart & Stark 2002 Fig. 9.16E ). Abdominal terga bearing microtrichia and socketed macrotrichia scattered over intercalary surface and forming a posterior fringe ( Fig. 40 ). Sexual dimorphism evident; males with developing hypoproct on sternum 9, and in pharate individuals evidence of developing dorsal genitalia on tergum 10 ( Stewart & Stark 2002 Figs. F, G). Cercal segments 24-26; cercomeres 1-10 bearing apical whorls of stout bristles, fine hairs and sensillae, bristles up to 0.40 times length of their segment ( Fig. 43 ). Middle and anteapical cercomeres bearing whorl bristles up to 0.20 times segment length, a single long ventral bristle up to 0.75 times segment length, and 2-3 fine intercalary hairs about 0.25 times length of their segment, all as seen laterally ( Figs. 8a , 44 ). Diagnostic characters: Cercal setation as described ( Figs. 8a , 43, 44 ).

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. 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. 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.