Hydropsyche rhadamanthys

Karaouzas, Ioannis, 2016, The larvae of Hydropsyche rhadamanthys Malicky 2001 and Hydropsyche sarpedon Malicky 2001 (Trichoptera: Hydropsychidae), endemics of Crete (South Aegean, Greece), with notes on their ecology, Zootaxa 4097 (4), pp. 557-566 : 558-560

Description of the 5th instar larva of Hydropsyche rhadamanthys

Body length: Ranging from 16 to 20 mm (n = 9) ( Fig. 1).

Head: Head in dorsal view (Figs. 2 & 3) rectangular, about as long (length: 1.6–1.9 mm, mean = 1.81 mm, S.D = 0.15, n = 8) as wide (width: 1.6–1.8 mm, mean = 1.73 mm, S.D = 0.07, n = 8). Cephalic capsule (Figs. 2 & 3) brown to light brown (caramel). Frontoclypeal apotome (Figs. 4 & 5) narrow, anterior margin and anterior sides straight and slightly concave, posterior region ogival with sides rounded, posterior tip pointed. Oral light spot usually absent (Fig. 4); visible or faint in light-colored specimens (Fig. 5). Lateral light spots clearly visible and most noticeable. Lateral aboral light spots usually absent or not visible. Median aboral light spot sometimes visible and rarely joined with lateral ones. In ventral view (Fig. 6), two distinctive longitudinal, wide, dark bands usually covering most of cephalic capsule except from area behind submentum. In lightly-coloured specimens, longitudinal bands lighter and not covering most of cephalic capsule. Submentum (Fig. 7) light brown (caramel), with lateral lobes short and wide (width-length ratio a:b: 0.21–0.24, mean = 0.22, S.D. = 0.01, n = 4).

Thorax. Notal plates brown to light brown. Metanotum lighter than pronotum and mesonotum ( Fig. 1). Pronotum and mesonotum usually of same colour as head. Median regions of posterior prosternites strongly pigmented, brown and irregularly oblong ( Fig. 8 ). Lateral regions of prosternites lighter, separated from median regions by light areas ( Fig. 8 ). Ventral gills present on mesosternum and metasternum.

Abdomen. Abdominal gills present on segment VII ( Fig. 1). Abdominal segments with two types of gills: single-stemmed gills and bifid-stemmed gills. Ventrolateral gills with bifid stalk on each side of abdominal segments I–VI. Ventromesal gills with single-stemmed stalk on each side of abdominal segments I–VII. Lateral (pleural) gills on each side of abdominal segments III–VII. Ventral plates on abdominal segment VIII subtriangular, brown-ochre, with tapered, short, thick spike-like setae emanating from prominent sockets; posterior border with long, thick black bristles. Ventral plates IX subtriangular, brown-ochre; setae on posterior parts of plates IX almost as long and thick as those of segment VIII; posterior borders with long, thick, black bristles ( Fig. 9 ). 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 hair-like setae lacking prominent setal sockets. Ventral membranous area covered with hairlike setae and lacking spike-like setae.

Figures

FIGURES 8 – 9. Hydropsyche rhadamanthys Malicky 2001. 8, posterior prosternites, ventral; 9, plates on abdominal sterna VIII and IX, ventral.