Cheumatopsyche trifascia Li 1988

Zhang, Ao & Zhou, Xin, 2021, The larvae of Chinese Hydropsychidae (Insecta: Trichoptera), Part II: Potamyia chinensis and Cheumatopsyche trifascia, Zootaxa 4926 (4), pp. 547-558 : 554-555

Cheumatopsyche trifascia Li 1988 (in Li & Dudgeon 1988)

( Figs 3 a– 3g)

HEAD. Head oval, 0.7 mm long, maximum width at middle of head 0.6 mm. Anterior margin of frontoclypeal apotome with large emargination in middle, entire margin crenulate, bearing series of small, rounded flanges. Lateral sides of frontoclypeus slightly narrower at eye level. Mediotransversal fold and tentorial pits of frontoclypeus not pronounced ( Fig. 3a ).

In dorsal aspect, dorsum of head mostly orange yellow, lacking pronounced markings. Anterior fourth of frontoclypeal apotome reddish brown, areas on posterior parietal sclerites along posterior third of frontoclypeal sutures slightly darkener. Muscle scars not pronounced but visible.

Secondary hairs on dorsum and sides of head tapered, blackish, often slightly curved. Hairs on anterior fourth of frontoclypeal apotome sparse; those on sides of head generally thicker than those on frontoclypeus. Posterior sixth of dorsum of head seta-less.

Ventral side of head slightly constricted at posterior two-fifths. Anterior ventral apotome sub-triangular, with anterior border concave, both subanterolateral corners angled; posterior ventral apotome minute, triangular; both anterior and posterior ventral apotomes dark brownish. Submentum trapezoidal, lateral borders suddenly narrower at midlength; posterior border convex; anterior border cleft, height of median incision about half as long as submentum ( Fig. 3b ). Ventral head mostly yellowish orange, striae of stridulating ridges not darker. Anterior half of ventrolateral areas of both parietal sclerites bearing tapered, clear, yellowish secondary setae.

THORAX. Thoracic nota generally yellowish to brownish, lacking distinct color patterns; all nota densely covered with long, tapered, dark hair-like setae; anterior borders all bearing dense row of long, curved, tapered hairs.

Pronotum subdivided longitudinally along mid-dorsal ecdysial line. Seta 22 at anterolateral corner of each side of pronotum prominent, long, thick. Posterior border of pronotum appearing black near posterolateral corners only, median portion not thicker, generally light brownish in dorsal aspect ( Figs 3c, 3d ).

Prosternal plate large, constricted laterally at posterior third, transverse anterior border and majority of transverse posterior border black. Posterior prosternal sclerites minute, each undivided ( Fig. 3e ).

Foretrochantins forked, each with dorsal branch seta-less, ventral branch setose. Dorsal branch shorter than ventral branch, basal end of dorsal branch about half as wide as that of ventral branch ( Fig. 3f ).

Posterior border of mesonotum with large, V-shaped, black marking on middle third with no lateral pieces. Secondary setae on mesonotum more or less curved.

Posterior border of metanotum with small, sub-triangular, black marking on middle ninth. Anterior and posterior ends of lateral borders black, middle half of each lateral border paler, brownish. Posterolateral corners of lateral borders each with small notch ( Fig. 3d ).

Thoracic ventral tracheal gills simple, each with single-stemmed, thick gill stalk and two to three gill filaments. Mesosternum with pair of submesal gills. Metasternum with pair of ventrolateral gills (coxal gills) and one single median gill situated on mesal line ( Table 3).

ABDOMEN. Abdominal segments bearing sparse, fine, dark, tapered hairs on pleura and sterna. Secondary setae on abdominal terga clear, transparent, scarcely visible. No scale hairs or club hairs present on abdominal segments.

Lateral gills (pleural gills) simple, finger-like, often clear and transparent. Abdominal segment III with one pair of lateral gills; segment IV with two; segments V and VI each with three; segment VII with one or two pairs of lateral gills ( Table 3).

Abdominal ventral gills of two typical hydropsychid types: single-stemmed gills and bifid-stemmed gills, stalks of all gills not segmented. Single-stemmed gills situated anteromesal to bifid gills on segments II–VI. Gill stalks or branches of bifid gill stalks thick and long, each stalk or each branch of bifid stalk bearing two to three gill filaments at apex. Abdominal sternum I with two pairs of single-stemmed gills (ventrolateral and ventromesal), situated very closely; sterna II–VI each with one submesal pair of single-stemmed gills and one sublateral pair of bifid gills; no ventral gills on segment VII ( Table 3).

Ventral sternites on abdominal VIII small, triangular, with light yellowish pigmentation. Anterior part of each sternite VIII with tapered, short, thick, golden setae; posterior border with long, thick, brownish bristles, pointing posterad. Ventral sternites IX larger, sub-triangular, mesal borders straight, light yellowish. Golden setae on anterior part of sternites IX longer than those on sternites VIII; each with posterior border bearing long, thick, brownish bristles, pointing posterad. Posteromesal corner of each sternite IX with seta-less area and small notch ( Fig. 3g ).

Figures

FIGURE 3. Cheumatopsyche trifascia Li 1988, larva. 3a, head, dorsal; 3b, head, ventral; 3c, pro-, meso-, and metanota, dorsal; 3d, pro-, meso-, and metanota, left lateral; 3e, prosternal plate and posterior prosternal sclerites, ventral; 3f, left foretrochantin, left lateral; 3g, right ventral sternites on sterna VIII and IX, ventral.