Hydropsyche perseus Malicky 2001

Hydropsyche perseus, 5th instar larva

(Figs. 1–7)

Body length: Ranging from 16 to 19 mm (n = 4; Fig. 1).

Head: Head in dorsal view (Fig. 2) rectangular, slightly longer (mean = 1.75 mm; n = 4) than wide (mean = 1.70 mm; n = 4). Cephalic capsule (Fig. 2) brown to reddish or dark brown. Frontoclypeal apotome (Fig. 4) longer than wide, ogival, anterior margin and anterior sides slightly concave, posterior sides rounded, posterior tip almost rounded. Oral light spot absent or faint. Lateral and aboral light spots joined on each side, leaving dark and elongate patch with Y shape in middle of apotome, with aboral light spots forming V or Y figure in posterior half of frontoclypeus. In ventral view (Fig. 3), with two distinct, broad, longitudinal, dark bands, usually covering stridulatory files and most of ventral cephalic capsule. These dark bands sometimes shorter and less wide. Submentum (Fig. 5) chestnut brown, triangular, with lateral lobes short and stout (width-length ratio: 0.21–0.23, mean = 0.22, n = 4).

Thorax: Notal plates brown to dark brown. Metanotum lighter than pronotum and mesonotum. Pronotum and mesonotum same colour as head. Median regions of posterior prosternites strongly pigmented, brown and irregularly oblong (Fig. 6); lateral regions of prosternites lighter, almost invisible, may be separated from median regions by light areas (Fig. 6). Ventral gills present on mesosternum and metasternum. Legs light brown; setae mainly dark; Forelegs prehensile, slightly shorter but thicker than midlegs and hind legs. Foretrochanters and forefemora on external (posterior) surfaces each with numerous long, dark, slender setae on ventral margin, mixed with row of several dark and pale, median, slender setae. Foretibiae longer than foretarsi, both with few short, pale, thick, spine-like setae on ventral margins and several long, pale, thick, spine-like setae on dorsal margins. Mid- and hind legs similar in size, shape, and structure. Trochanters and femora of mid- and hind legs each with several median, pale and dark, spine-like setae on ventral margin and few dark, longer, and slender setae; tibiae and tarsi of mid- and hind legs each with short, pale, spine-like setae and 1 dark, long, slender seta on apicodorsal margin of tarsus.

Abdomen: Abdominal gills present on segment VII (Fig. 1). Pair of sternites VIII subtriangular, brown, with tapered, short, thick setae; posterior borders of these sternites with very long, thick black bristles. Pair of sternites IX subtriangular, light brown; setae on posterior parts of these sternites longer and thicker than those of segment VIII; posterior borders of these sternites with long, thick, black bristles (Fig. 7). Anal prolegs each with bent claw and cluster of tapered, dark, long, slender setae. Ventral side of each anal proleg bearing series of tapered, long, dark setae lacking prominent setal sockets. Ventral membranous areas covered with hair-like setae, lacking spikelike setae.