Nemoura papilla Okamoto, 1922

Teslenko, Valentina A., 2016, Larvae of two East-Asian species of Nemoura (Plecoptera: Nemouridae), Zootaxa 4162 (2), pp. 381-390 : 381-386

Nemoura papilla Okamoto, 1922

( Figs. 1 –12).

Okamoto 1922. Bull. Agric. Exp. Stn. Chosen, Suigen 1(1):1–46 + Tafe l I–VI (original description of male and female); Shimizu, 1994, Aquatic Insects, 16(4): 221–223 ( Nemoura papilla Okamoto, 1922 = Nemoura denticulata Kawai, 1954 , syn. nov. and N. levanidovae Zwick, 1974 , syn. nov.) (supplementary description of the epiproct, male and female).

Material examined. Russian Far East, Primorsky Region: 6 males, 26 females, 35 larvae, Anan’evka River , Razdol’naya River Basin , upper Venevitinovo Settlement , N 43º24.476’ E131º44.302’, 27.04−4.05.2015, rearing, coll. V. Teslenko ; 15 larvae, Vladivostok , Rybachiy Sett., Meortvaya Pad Stream, N 42°080.417’ E 132°021.346’, 28.07.− 16.08.2015, coll. V. Teslenko .

Mature larva ( Figs. 1 −12). Body relatively slender, length in males, 5.5–6.4 mm; in females 6.8–7.8 mm. General color a mottled brown with specific pattern consisting of pale and dark brown patches on head, legs, and cerci, and a pale mesal stripe on thorax ( Figs. 1, 2 ). Head with pale, tentorial callosities outlined by contrasting unconnected dark brown lines towards posterior ocelli, a rectangular brown interocellar patch with thin longitudinal pale line medially, a diffuse brownish patch in front of the anterior ocellus extending to clypeus ( Fig. 2 ). Epicranial suture appear as pale Y mark between the lateral ocelli; an oval, oblique pale patch to the inside of each compound eye. Occiput with pair of oval oblique pale patches surrounded by thread-like brown loops, posterior margin darkened ( Fig. 2 ). Antenna brown, long, length reaches 85−100% of body length; scape and pedicel dark brown. Pronotum oval, approximately 1.2 X wider than long, pattern diffuse, with small dark brown spots and pale patches of different size and form; narrow pale mesal stripe on pronotum continues over meso-, metanotum and abdominal segments ( Figs. 1, 2 ). Meso- and metanotum with U-shaped brown pattern and diffuse pale patches anteromedially. Legs slender, long with contrasting brown and dark brown bands and pale patches. Femora brown with diffuse dark brown band in the distal ⅓ and one pale patch apically, sometimes with a bald median pale line ( Figs. 1, 2 ). Fore femur 3.3 X longer than wide ( Fig. 6 ) and hind femur about 4.1−5.0 X longer than wide. Tibia brown with two diffuse dark brown bands in the basal and distal ⅓ ( Figs. 1, 2 ) and two pale patches basally and distally. Third tarsal segment darkened basally and distally, pale medially. Abdomen relatively slender, integument light, matte in appearance, terga brownish with a mesal row of pale small patches forming a medial longitudinal band ( Figs. 1, 2 ). Cerci pale, very long, length reaches 100−133% of body length, with 31−33 segments, each segment darkened basally and distally, pale medially; the segment sides are nearly parallel in basal part of cercus, club-shaped in middle and apical parts, apical segments very long, 25X longer than wide ( Figs. 1, 2 , 9).

Setation weakly visible. Setal fringe around the pronotum relatively spaced, consisting of club-shaped bristles of different length ( Figs. 3, 4 ). Few longest club-shaped bristles present at the posterior corners, the longest bristles approximately equal 4.9−5.5% of pronotum width. Pronotum disc bears tiny oval setae with widened apex, short club-shaped setae, and occasional long hairs ( Figs. 3, 4 ). Outer wing pad margin covered with club-shaped bristles; tiny club-shaped setae in the lines on wing-pads ( Fig. 5 ). Legs with markedly heterogeneous chaetotaxy ( Figs. 6, 7 ). All femora covered with spatulate bristles of different length, occasionally fine procumbent setae and seldom thin long hairs ( Figs. 6, 7 ). Setal fringe on outer femur margin in the apical half consisting of three long, clubshaped bristles in an irregular arrangement on fore leg, and with five long, club-shaped bristles on hind leg ( Figs. 6, 7 ). The longest club-shaped bristles reach 37% of the width of femur on fore leg, and 26% of the hind leg. Tibia with sporadic fine procumbent setae, dense and strong spine-like bristles along the inner edge, the bristles not longer than width of tibia; the outer edge bears tiny club-shaped setae ( Fig. 6 ). Terga covered with sparse short club-shaped bristles. The posterior tergal margins feature mostly short club-shaped bristles and one pair of conspicuous relatively long slightly curved club-shaped bristles (Fig. 8). Length of the longest bristles on terga 5−6 reaches 34% of segment length (Fig. 8). Cercal chaetotaxy heterogeneous, bristles of different form and size in the apical whorl; intercalary setation very sparse and almost invisible (Figs. 10−12). Apical whorl comprises a set of club-shaped bristles on basal cercal segments; the longest club-shaped bristles reach 67% of segment length on cercal segments 8−10 (Fig. 10). In the middle part of cerci the apical whorl bears tiny setae with rounded apex mixed with long, acute bristles, which do not exceed 59% of the segment’s length on cercal segments 16−17 (Fig. 11). On apical cercal segments the apical whorls include tiny setae with rounded apex and one or two thin acute bristles (like hairs), bristle length is only about 16% of segment length at cercal segment 31 (Fig. 12).

Diagnosis. The larvae of N. papilla can be separated from known larvae of East-Asian Nemoura species by mottled contrasting body pattern, long antenna, cerci exceeding the body length, weak but conspicuous variable setation on the legs and cerci. Setal fringe of the pronotum sparse with club-shaped bristles, club-shaped bristles of different size present also in setal fringes along outer wing pad margin, outer femur margin, posterior margins of terga and in the apical whorls on basal cercal segments. Setation of femur also includes a few long club-shaped bristles and special spatulate bristles. The medial apical whorl of the cerci differs from the apical whorl on basal segments having long acute bristles not exceeding 59% of segment length at cercal segments 16−17. Intercalary setation on cercal segments sparse and almost indiscernible.

Distribution. Nemoura papilla is an East Asian mainland and insular, widely distributed species originally described from Japan, but also known from the southern Kuril Islands, Sakhalin Island, mainland Russian Far East (RFE), China, and Korea (Teslenko, 2015). The flight period extends from May to July. Larvae of N. papilla inhabit mountain streams and rivers, occurring in pools with silty substrate.

Figures

FIGURES 1 – 2. Larva of Nemoura papilla, habitus, dorsal view, not to scale.

FIGURES 3 – 7. Larva of Nemoura papilla. 3. Сlub-shaped bristles near midline on anterior margin of pronotum. 4. Setae on disc and setal fringe of right anterior corner of pronotum. 5. Bristles on outer margin and rows of tiny setae on wing pad. 6. Right fore leg. 7. Setal fringe on outer femur margin on hind leg with five long club-shaped bristles Scale (mm): 3 – 5 = 0.1; 6 = 0.3; 7 = 0.05.