Bioacoustics of Hydropsyche (Hydropsyche) cetibeli

Body length : Ranging from 16 to 19 mm (n = 6), ( Fig. 1 ). Head: Head in dorsal view ( Figs. 2 & 3 ) rectangular, almost as long (mean = 1.83 mm ; S.D = 0.02; n = 6) as wide (mean = 1.75 mm ; S.D = 0.04; n = 6). Cephalic capsule ( Figs. 2 & 3 ) light brown to brown (chestnut). Frontoclypeal apotome ( Fig. 4 ) longer than wide, (width of anterior edge similar to width of posterior third), ogival, anterior margin and anterior sides concave, posterior sides rounded, posterior tip almost rounded. Oral light spot absent from all examined specimens. Lateral and aboral light spots always 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. 5 ), two longitudinal and wide dark bands distinctive, usually covering stridulatory files and most of cephalic capsule. These dark bands sometimes shorter and less wide. Submentum ( Fig. 5 ) light brown, with lateral lobes short and wide (width-length ratio: 0.22–0.25, mean = 0.24, S.D. = 0.02, n = 4). Seta 9 of dorsal surface dark, slender and long; longer than other setae of head; seta 1 long, dark and longer than other setae of anterior margin of frontoclypeus; seta 7 dark, slightly shorter and thinner than seta 9, but almost equal to seta 1; ventral seta 8 similar to seta 7; seta 11 situated on outer side, pale, thin, and short; seta 10 pale, small, situated anterior to eye; seta 14 long, dark, situated posteriorly to eye; Secondary setae numerous, short and spine-like, dorsolateral on each side of head. Thorax : Notal plates light brown to brown. Metanotum lighter than pronotum and mesonotum. Pronotum and mesonotum same colour as head. Median regions of posterior prosternites strongly pigmented, light brown (chestnut) and irregularly oblong ( Fig. 6 ); lateral regions of prosternites lighter, 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. Anterior margin of each forecoxa with 5 thick, dark brown, short spine-like setae and long, dark, primary basal seta; several dark, short, spine-like setae at posterior margin; at external (posterior) surface, one very long dark, thick, ventral seta reaching 2/3 of trochanter. 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 midlegs each with several median, pale and dark, spine-like setae on ventral margin and one dark, very long, slender seta; trochanters of hind legs, each with several median, pale, spine-like setae on ventral margin and one dark, very long, slender seta; femora of hind legs each with several short, thick, pale, spine-like setae on ventral margin. 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 absent from segment VII ( Fig. 1 ). Abdominal sterna with two types of gills: singlestemmed gills and bifid-stemmed gills. Pair of ventrolateral gills with bifid stalks on each of abdominal segments I–VI. Pair of ventromesal gills with single stems on each of abdominal segments II–VI. Pair of lateral (pleural) gills on each of abdominal segments III–VII simple, finger-like. Pair of sternites VIII subtriangular, brown, with tapered, short, thick setae; posterior borders of these sternites with long, thick black bristles. Pair of sternites IX subtriangular, 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 spike-like setae.