Ostrocerca Ricker, 1952

Grubbs, Scott A. & Baumann, Richard W., 2023, The Nemourinae (Insecta, Nemouridae) of the eastern Nearctic, Zootaxa 5306 (1), pp. 1-53 : 9-10

III. Genus Ostrocerca Ricker, 1952

http://lsid.speciesfile.org/urn:lsid: Plecoptera .speciesfile.org:TaxonName:6133

Type species. Nemoura foesteri Ricker, 1943

Range. Nearctic ( DeWalt et al. 2022).

Diagnosis. See Baumann (1975) for a comprehensive description of the genus and Young et al. (1989) for an SEM-based treatment for all six Nearctic species.

Species key to eastern Nearctic Ostrocerca adult males and females

1 Males .............................................................................................. 2

- Females............................................................................................. 5

2 Epiproct ventral sclerite apex a singular unit apically and expanded laterally ( Figs. 20 , 38 )........................... 3

- Epiproct ventral sclerite apex sclerite secondarily divided apically into pair dorsal processes and a singular ventral process ( Figs. 26‒27 , 32‒33 )................................................................................... 4

3 Epiproct with a T-shaped ventral sclerite apically ( Fig. 21 ), dorsal sclerite with recurved, paired lateral arms visible in dorsal view ( Figs. 20‒22 )......................................................................... O. albidipennis

- Epiproct with a bell-shaped ventral sclerite apically ( Figs. 37‒38 ), dorsal sclerite with paired lateral arms not recurved and visible in ventral view ( Figs. 39‒40 ).............................................................. O. truncata

4 Epiproct ventral sclerite terminating in paired processes apically, not recurved and in similar dorsal plane as singular process ( Figs. 26‒27 )................................................................................ O. complexa

- Epiproct ventral sclerite terminating in paired, dorsally-recurved processes apically, singular process ventrally displaced ( Figs. 32‒33 ).................................................................................... O. prolongata

5 7 th sternum not produced and extended over 8 th sternum, subgenital plate of 8 th sternum with subtriangular lateral projections and medially truncate ( Figs. 41‒42 )............................................................... O. truncata

- 7 th sternum produced over anterior margin of 8 th sternum as a nipple-like process, subgenital plate of 8 th sternum with gently rounded or subangular lateral corners and medially concave ( Figs. 23‒24 , 29‒30 , 35‒36 )............................ 6

6 7 th sternum slightly produced over anterior margin 8 th sternum, subgenital plate of 8 th sternum with gently rounded lateral corners and concave in medial ⅓ ( Figs. 23‒24 )................................................... O. albidipennis

- 7 th sternum produced at least ¼ of anterior margin 8 th sternum, subgenital plate of 8 th sternum with subangular lateral corners and concave in medial ½ ( Figs. 29‒30 , 35‒36 )..................................... O. complexa and O. prolongata

Figures

FIGURES 19‒24. Ostrocerca albidipennis. 19, male abdominal terminalia, dorsal view; 20, USA, New York, Oquaga Creek, male abdominal terminalia, dorsal view; 21, USA, New York, Oquaga Creek, epiproct, dorsal view; 22, USA, New York, Oquaga Creek, epiproct, ventral view; 23, female abdominal terminalia, ventral view; 24,USA,Ohio, tributary Pike Run, female abdominal terminalia, ventral view. c = cercus, ds = dorsal sclerite, ipl = outer paraproct lobe, la = lateral arm, sgp = subgenital plate, vs = ventral sclerite.

FIGURES 37‒42. Ostrocerca truncata. 37, male abdominal terminalia, dorsal view; 38, Canada, Ontario, Clare River, male abdominal terminalia, dorsal view; 39, Canada, Ontario, Clare River, epiproct, lateral view; 40, male abdominal terminalia, ventral view; 41, USA, New York, Cascadilla Creek, female abdominal terminalia, ventral view; 42, USA, West Virginia, headwaters Davis Creek, female abdominal terminalia, ventral view. c = cercus, ds = dorsal sclerite, hy = hypoproct, ipl = inner paraproct lobe, la = lateral arm, sgp = subgenital plate, vs = ventral sclerite.

FIGURES 25‒30. Ostrocerca complexa. 25, male abdominal terminalia, dorsal view; 26, USA, New York, Stoney Creek, epiproct, dorsal view; 27, USA, New York, Stoney Creek, epiproct apex, dorsolateral view; 28, USA, New York, Stoney Creek, epiproct, caudal view; 29, female abdominal terminalia, ventral view; 30, USA, West Virginia, tributary Hills Creek, female abdominal terminalia, ventral view. bc = basal cushion, c = cercus, ds = dorsal sclerite, hy = hypoproct, ipl = inner paraproct lobe, sgp = subgenital plate, vs = ventral sclerite.

FIGURES 31‒36. Ostrocerca prolongata. 31, male abdominal terminalia, dorsal view; 32, Canada, Quebec, tributary to Lac Croche, epiproct, dorsal view; 33, Canada, Quebec, tributary to Lac Croche, epiproct, lateral view; 34, Canada, Quebec, tributary to Lac Croche, epiproct, ventral view; 35, USA, West Virginia, Seneca Creek, female abdominal terminalia, ventral view; 36, USA, West Virginia, Gandy Creek, female abdominal terminalia, ventral view. bc = basal cushion, c = cercus, ds = dorsal sclerite, hy = hypoproct, ipl = inner paraproct lobe, sgp = subgenital plate, vs = ventral sclerite.