Hydromanicus umbonatus Li 1993

Zhang, Ao & Zhou, Xin, 2021, The larvae of Chinese Hydropsychidae (Insecta: Trichoptera), Part III: Hydromanicus melli Complex, H. canaliculatus, and H. umbonatus, Zootaxa 5026 (4), pp. 527-540 : 536-538

Hydromanicus umbonatus Li 1993 (in Tian et al. 1993)

( Figs 4a–4i )

HEAD. Head quadrate, 1.4 mm long, 1.3 mm wide. Dorsum of head dark brown, each eye circled by pale mark, posterior parietals light-colored. No obvious mark on dorsum of head. Muscle scars light-colored, with dark borders, visible on posterior parietals and posterior half of frontoclypeal apotome. Frontoclypeus narrowed near tentorial pits. Anterior margin of frontoclypeus complete, symmetrical, cenulate, bordered by row of thick, blunt, yellowish, semitransparent, truncate-peg setae, pointing anterodorsad ( Fig. 4c , anteroventral aspect). In dorsal aspect, anterior two-third of both parietals, anterior fifth and posterior fifth of frontoclypeus covered by dense, thick, blunt, black, secondary, truncate-peg setae, with scattered thin, tapered, dark, acuminate-peg setae, all pointing anterad or anterolaterad ( Fig. 4a , inset of setae). Golden secondary setae situated inside pale marks around eyes. Posterior third of parietals (often retracted underneath pronotum) seta-less.

Ventral side of head brown. Muscle scars visible on posterior half. Submentum trapezoidal, concave anterior and convex posterior borders parallel, each anterolateral corner bearing tuft of black bristles, each posterolateral corner with short diagonal stripe extending anteromesad, end of each stripe bearing two short, black, acuminate-peg setae ( Fig. 4b ). Anterior ventral apotome subtriangular, with round anterolateral angles. Posterior ventral apotome small, triangular, dark. Longitudinal outlines of stridulating files curved slightly laterad anteriorly. Secondary acuminatepeg setae on lateral side of each gena clearly visible in ventral aspect of head, longer setae thick, tapered, black; shorter setae tapered, dark ( Fig. 4b , inset of setae).

THORAX. Thoracic nota dark brown, densely covered with secondary setae. Anterior 3/4 of pronotum with blunt, thick, black, truncate-peg setae and scattered short, tapered, dark acuminate-peg setae. Posterior fourth of pronotum with only short, tapered, thin hairs. Middle half of anterior margin of pronotum lighter in color. In dorsal and lateral aspects, sub-basal surface of pronotum slightly constricted; lateral margins of pronotum each with broad black border; posterior border with light, transverse stripes immediately anterior and posterior of transverse black line. Seta 22 on each anterolateral corner of pronotum prominent, long, thick, black; pair of sa 2 setae about 3/5 distance from anterior margin.

Mesonotum with similar coloration and setation as pronotum. Anterior margin of mesonotum with thin, black border bearing short, blunt, black, truncate-peg setae and scattered thin, curved, tapered, dark brown, acuminatepeg setae about twice as long, all pointing cephalad ( Fig. 4d , inset of setae). Lateral border of each side black, bearing thick, truncate-peg setae; primary seta 5 (sa 3) above black border and about 1/3 distance from anterior margin. Posterior border of mesonotum with black mark in middle 3/5, wide and curved, with each lateral angle bent posterolaterad, continuing laterad as light-colored stripe. Posterior mesonotum with transverse row of four dark primary setae (sa 2). Diagonal groove extending from each anterolateral corner inconspicuous.

Metanotum slightly lighter in color than meso- and pronota.Anterior margin with thin, black border, and setation similar to that of mesonotum. Lateral border of each side black, bearing thick, truncate-peg setae; primary seta 5 (sa 3) above black border and about 1/3 distance from anterior margin. Posterior border with small, black mark in middle fifth. Posterior metanotum with pair of dark primary setae (sa 2) about 4/5 distance from anterior margin. Diagonal groove extending from each anterolateral corner inconspicuous.

Anterior border and 2/3 of posterior border of prosternal plate black; prosternal plate constricted at posterior third. Posterior prosternal sclerites with single sclerite on each side, subparallelogram-shaped, posterior border with triangular notch near posterolateral corner, acute anterolateral corner of each sclerite dark, remainder of posterior prosternal sclerite uniformly light brown.

Foretrochantin of each side forked, dorsal branch seta-less, ventral branch bristly. Dorsal branch about same as long as ventral branch, slightly narrower basally. Dorsal branch straight, with acute, pigmented tip; ventral branch with blunt, round tip slightly curved anterodorsad ( Figs 4g, 4h ).

Thoracic ventral gills similar to those of the H. melli Complex.

ABDOMEN. Dorsa and pleura of abdominal segments covered with dense reddish brown hairs. Three types of secondary setae identifiable on dorsa of abdominal segments: (1) hair-like setae (hs): small, fine, with pointed tip; (2) club hair (ch): long, thick, with relatively blunt tip ( Schuster & Etnier 1978); (3) scale hair (sh): long, darker, with enlarged tip and truncate end ( Fig. 4i ). All secondary setae depressed dorsoventrally, hair-like setae and clubhairs lying close to body surface, scale hairs and primary setae (ps) erect, directed away from body surface.

Abdominal gills (ventral and pleural gills, Table 2) and other abdominal characteristics similar to those of the H. melli Complex.

Diagnosis. The larva of Hydromanicus umbonatus can be easily differentiated from H. canaliculatus and the H. melli Complex by the presence of densely distributed secondary setae on dorsal and lateral surfaces of head and thoracic nota. Additionally, the anterior margin of the frontoclypeus in H. umbonatus is complete and symmetrical. Based on descriptions by Prommi & Permkam (2015) and Genco et al. (2020), the larvae of H. inferior and H. calyx are very similar to that of H. umbonatus described here. The main difference between the two species appears to be the hair type found on abdominal segments: Those of H. umbonatus could be more morphologically diverse ( Fig. 4i in this study), whereas H. inferior has only primary (ps) type setae (Fig. 58, Prommi & Permkam 2015). However, these differences need to be confirmed by simultaneous comparison.

Figures

FIGURE 4. Hydromanicus umbonatus Li 1993 (in Tian et al. 1993), larva. 4a, head, dorsal, with inset of setae on dorsal surface of left gena; 4b, head, ventral, with inset of setae on ventrolateral surface of right gena; 4c, anterior margin of frontoclypeal apotome, anteroventral aspect; 4d, thoracic nota, dorsal; 4e, thoracic nota, left lateral; 4f, prosternal plate and posterior prosternal sclerites, ventral; 4g, left foretrochantin, left lateral; 4h, left foretrochantin, mesal; 4i, setae on dorsal surface of abdominal segment I (hs = hair-like seta; ch = club hair; sh = scale hair; ps = primary seta).