VI. Genus Prostoia Ricker, 1952

http://lsid.speciesfile.org/urn:lsid: Plecoptera .speciesfile.org:TaxonName:6092

Type species. Nemoura completa Walker, 1852

Range. Nearctic (DeWalt et al. 2022).

Diagnosis. See Baumann (1975) for a comprehensive description of the genus and Grubbs et al. (2014) for an SEM-based treatment for all five species.

Species key to eastern Nearctic Prostoia adult males and females

(modified from Grubbs et al. 2014)

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

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

2 Dorsal sclerite with secondarily reduced lateral arms (Fig. 79); ventral sclerite bears an ornate, secondarily divided process apically (Figs. 70, 72‒73)......................................................................... P. hallasi

- Dorsal sclerite possesses lateral arms (Figs. 66, 82, 88); apex of ventral sclerite simple, not divided apically (Figs. 61, 77, 85) ................................................................................................... 3

3 Lateral arms longer and sinuous, reaching nearly to ½ the length of the ventral sclerite (Figs. 85‒87)............. P. similis

- Lateral arms shorter, extending <¼ the length of the ventral sclerite (Figs. 66, 82).................................. 4

4 In dorsal view, ventral sclerite parallel-sided in basal ⅓ (Fig. 61); lateral arms sickle-shaped, gradually recurved (Figs. 66‒67)........................................................................................... P. completa

- In dorsal view, ventral sclerite gradually widening in basal ⅓ (Fig. 77); lateral arms somewhat triangular in shape, tips flared laterally (Figs. 74, 82‒83).................................................................... P. ozarkensis

5 7 th and 8 th abdominal sterna not fused medially (Fig. 75‒76), with a well-developed subgenital plate that is convex, extending over the anteromedial margin of the 9 th sternum and slightly notched medially (Figs. 75‒76).................... P. hallasi

- 7 th and 8 th abdominal sterna fused medially, subgenital plate not convex and bearing a distinct medial notch or not (Figs. 68, 84, 93‒94).............................................................................................. 6

6 Posterior margin of 8 th sternum with a distinct medial notch, lateral lobes of subgenital plate distinctly angular, projecting ca. 1/4 over anterior margin of 9 th sternum (Figs. 93‒94).................................................. P. similis

- Posterior margin of 8 th sternum with a shallow medial notch, lateral lobes scarcely projecting posteriorly (Figs. 68, 84).................................................................................. P. completa and P. ozarkensis