Further Descriptions Of Western North American Podmosta Larvae And Their Separation From Ostrocerca Larvae (Plecoptera: Nemouridae) Author Stewart, Kenneth W. and Bill P. Stark & Department of Biological Sciences, P. O. Box 305220, University of North Texas, Denton, Texas 76203, U. S. A. E-mail: stewart @ unt. edu stewart@unt.edu Author Stark, Bill P. Box 4045, Department of Biology, Mississippi College, Clinton, Mississippi, U. S. A. 39058 E-mail: stark @ mc. edu stark@mc.edu text Illiesia 2011 7 10 104 117 journal article 6866 10.5281/zenodo.4760091 3b644b6a-2a10-4153-9a6b-11ed35c7526e 1854-0392 4760091 Podmosta delicatula ( Claassen) ( Figs. 2, 3, 5, 9-12 , 17 , 30 , 45, 46 ) Distribution. Widespread in Rocky Mountains, Great Basin, Pacific Northwest ( New Mexico , Nevada and California , northwestward to Alaska ). Material examined. Colorado : Larimer Co. , Buckhorn Creek , 32 km north of Masonville , 31-V-1986 , B.C. Kondratieff , 2♂ , 2♀ , 1♂ larva, 3♀ larvae, 1 exuvium . Oregon : Umatilla Co. , Meachum Creek and tributaries at and upstream of Hwy. 84 and adjacent railroad bridges, 26-IV-2004 , K.W. Stewart , B.J. Armitage , 12♂ larvae, 17♀ larvae ( 121 adults , all P. delicatula , in Monte L. Bean Life Science Museum , Brigham Young University , collected at this site) . Characters. Body length ♂ 4.2-4.5 mm , ♀ 4.3-5.5 mm , light brown above, with mottled dark head pattern, distinct light interocellar spot and light mesal stripe on thorax ( Fig. 2 ). Antennal segments approximately 38, head capsule width ♂ 0.78-0.88 mm , ♀ 0.84-0.96 mm ; eyes large, head wider than pronotum ( Fig. 2 ). Gills absent. Mandibles with 5 or 6 apical teeth; right mandible with raised molar pad (as in other species) that grinds against opposing, depressed molar cup of left mandible ( Fig. 17 ) as in a “mortar- pestle” action, molar cup with outer (dorsal) comb of curved teeth ( Fig. 17 ). Lacinia triangular, palmate, with scalloped palm surface, similar to other species. Pronotum bearing short bristles and sensillae scattered over surface and lacking distinct lateral fringe ( Fig. 30 ). Metathoracic wingpads bearing short bristles scattered over surface, and tuft of short bristles on anterolateral corners. Femora bearing short bristles and hairs scattered over dorsal surface, longer bristles apicodorsally ( Fig. 3 ). Tibiae bearing scattered short bristles and few (5-8) posterior silky fringe hairs ( Fig. 3 ). Mesosternal Y-ridge faint, closed by an anterior ridge forming a rectangular area. Abdominal terga bearing microtrichia and socketed macrotrichia scattered over intercalary surface and forming a posterior fringe. Sexual dimorphism evident; males with developing hypoproct on sternum 9 ( Fig. 10 ) and in pharate individuals evidence of developing dorsal genitalia ( Figs. 9, 11 ). Cercal segments 22-24; cercomeres 1-10 bearing apical whorls of stout bristles, fine hairs and sensillae, bristles up to same length as their segment ( Fig. 45 ). Middle and anteapical cercomeres bearing long whorl bristles up to 0.60 times length of their segment, and 3-6 fine intercalary hairs up to 0.30 times length of their segment, ( Fig. 46 ) all as seen laterally. Diagnostic characters: light interocellar spot ( Fig. 2 ), and cercal setation as described ( Figs. 45, 46 ).