. Bulletin. Natural history; Natural history. September, 1942 Prison : North American Plecoptera 277 three spots on posterior margin. Head without a transverse occipital ridge on posterior margin between compound Fig. 43.— Acrnnruria filicis. Maxilla, labium and mandibles as in fig. 43. Anal gills present at apex of abdomen. Approximately full grown female nymph 25 mm. and male somewhat smaller. This nymph in general resembles the nymphs of evoluta Klapalek (= arida of Frison 1935«), perplexa Frison and niela Frison, having in common with them anal gills. Differences in color pattern wh
. Bulletin. Natural history; Natural history. September, 1942 Prison : North American Plecoptera 277 three spots on posterior margin. Head without a transverse occipital ridge on posterior margin between compound Fig. 43.— Acrnnruria filicis. Maxilla, labium and mandibles as in fig. 43. Anal gills present at apex of abdomen. Approximately full grown female nymph 25 mm. and male somewhat smaller. This nymph in general resembles the nymphs of evoluta Klapalek (= arida of Frison 1935«), perplexa Frison and niela Frison, having in common with them anal gills. Differences in color pattern which seem to have taxonomic significance are as follows: (1) \n evoluta (Frison 1935(3, fig. 313) the pale yellow color of the head behind the ocelli tends to invade the space between the ocelli and compound eyes; the transverse dark bands of the abdominal tergites are usually confined to the an- terior half of each tergite; and the trans- verse band on head anterior to median ocellus is more bandlike and less W- shaped. (2) In iiiela (Frison 1935^, fig. 316) the abdominal tergites are almost entirely dark, and three light spots, in- stead of a W-shaped transverse band, are present on the head anterior to the median ocellus. (3) In per-plexa (Frison 1937, fig. 66) the dark markings on the ab- dominal tergites are mostly on the anterior half of each tergite and decrease in width near lateral margins, and the W-shaped mark on the head is less broad throughout. Nymphal and exuvial records are as fol- lows. North Carolina.—East fork of Tuckasee- gee River, Jackson County: June 19, 1939, T. Howell, 1 nymph. Blowing Rock Mountain : March 23, 1940, T. H. Frison, C. O. Mohr & A. S. Hawkins, 1 nymph. Tennessee.—Ozone: June 11, 1935, H. H. Ross, 1 exuvia. Gatlinburg, Le Conte Creek: June 13, 1938, T. H. Frison & T. H. Frison, Jr., 2 nymphs; June 18, 1938, T. H. Frison & T. H. Frison, Jr., 1 exuvia; June 14, 1940, T. H. Frison et al., 2 exuviae (adult $ reared from 1 exu
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