Hydropsyche uvana Mey 1995

Ge, Xinyu, Wang, Yinchang, Wang, Beixin & Sun, Changhai, 2020, Descriptions of larvae of three species of Hydropsyche Pictet 1834 (Trichoptera Hydropsychidae) from China, Zootaxa 4858 (3), pp. 358-374 : 367-370

Hydropsyche uvana Mey 1995

General Description. Larvae (5th instar). Body grayish yellow in alcohol. Head, pronotum, legs, and anal claws yellowish brown.

Head. Head ( Fig. 8A ) capsule mostly yellowish brown, subquadrate, nearly square, 1.2 mm long, 1.0 mm wide in dorsal view. Frontoclypeal apotome dark brown, with three yellow spots arranged longitudinally, anterior spot transversely elliptical, somewhat connected with middle one, forming mushroom-shaped pattern with it, posterior spot subtriangular, with two sides parallel to frontoclypeal sutures. Frontoclypeal apotome with mediotransversal fold arm inconspicuous, anterior margin slightly convex, posterior angle ogival, angled about 70°, and posterior portion of each frontoclypeal suture slightly sinuous. Parietal in lateral view whitish yellow, ( Fig. 8B ), eyes oval, black. In ventral view ( Fig. 8C ), pair of files brown, parietals otherwise yellow; anterior ventral apotome nearly triangular, brown, with anterior border slightly concave and anterolateral angles rounded. Ventral ecdysial line about 2.5 times length of anterior ventral apotome. Posterior ventral apotome tiny, triangular, dark brown. Dorsum of head with brown hair-like setae, short and dark brown truncate peg-like setae, and short acuminate peg-like setae. Labrum dark brown, with its anterior margin convex and hair brush at each anterolateral corner. Mandibles ( Fig. 8D ) triangular, dark yellow basally and mostly black in ventral view, each with two apical teeth and 3 subapicomesal teeth; left mandible with about 10 setae at lateral margin and with brush of about dozen stiff hairs at middle of inner side. Right and left mandibles nearly symmetrical. Submentum ( Fig. 8E ) in ventral view with basal 2/3 somewhat trapezoidal and distal 1/3 divided, forming two lobes; posterior margin slightly convex; each anterolateral corner with some long, strong setae and many short setae. Maxillae each with cardo sub-rectangular, brown. Stipes ( Fig. 8F ) each with three clusters of setae, one cluster with about 10 setae on membranous portion of stipes, 9 setae and 7 setae on lateral and medial areas of triangular sclerotized part of stipes, respectively. Maxillary palps each 5-segmented, galea adjacent to mesal margin of palp ( Fig. 8F ). Labium ( Fig. 8F ) triangular and short with brown mentum in ventral view.

Thorax. Pronotum ( Fig. 9A ) yellowish brown, subrectangular, subdivided by pronotal suture; with anterior margin straight, and posterior margin slightly concave; posterior border black submesally, otherwise mostly dark brown in dorsal view. Pronotum covered with dark acuminate peg-like setae; short and brownish yellow transparent truncate peg-like setae; and slender, short, black hair-like setae; these three types of setae intermingled along anterior margin. Prosternal plate ( Fig. 9B ) trapezoidal, width about four times its length; anterior margin dark brown with lateral corners more extensively dark brown; posterior half with transverse black stripe. Pairs of lateral sclerite pieces and submesal sclerite pieces behind prosternal sclerite fused into pair of subrhomboid sclerites ( Fig. 9B ), each with triangular notch posterolaterally. Mesonotum ( Fig. 9C ) pale yellow, anterior margin with dark brown bor- der especially anterolaterally, anterolateral angles and lateral margins and posterolateral angles with wide black borders; posterior margin with black arc-shaped stripe at middle; paired brown lines each issuing from posterolateral angles and extending anteromesad to level of ends of above-mentioned black arc-shaped stripe. Diagonal groove inconspicuous. Muscle scars darker than background; dense brownish hair-like setae and sparse dark brown truncate peg-like setae scattered over whole surface of notum. Metanotum ( Fig. 9D ) of same color as mesonotum; posterior margin shallowly concave, with mesal black mark, paired brown lines each issuing from posterolateral angle connected with black mark; diagonal grooves more conspicuous than those of mesonotum. Muscle scars darker than background, longitudinally arranged. Anterior margin with dense brownish hair-like setae and sparse dark brown truncate peg-like setae. Truncate peg-like setae on metanotum fewer than those on pronotum and mesonotum. Mesothorax and metathorax with one and two pair of single-stemmed ventral gill, respectively.

Legs. Legs ( Figs 10A, 10C, 10D ) yellowish brown. Forelegs slightly shorter and thicker in structure and darker in color than mid- and hind legs. Each foretrochantin bifurcate ( Fig. 10B ), two branches divergent at an angle of about 60º, with about 12 setae, upper branch slender, lower one stout. Forecoxae shorter than mid- and hind coxae, and conical in lateral view. Dorsal margin with more than ten spike-like setae. Trochanters each two-segmented and triangular, each with basal segment subtriangular and shorter than subtriangular apical segment, ventral trochanteral brush present on forelegs, with more than 20 spike-like setae and 2 or 3 long-slender setae. Forefemora in lateral view pentagonal, each with dorsal margin (scraper) protruding in middle; ventral and dorsal margins with many long-slender setae and dense spike-like setae, respectively. Foretibiae and foretarsi tube-like, stouter than those of mid- and hind legs. Tarsal claws of forelegs slightly curved downwards, with basal seta small. Mid- and hind coxae cylindrical, with dense spike-like setae. Trochanters each two-segmented and approximately triangular with dense spike-like setae and 2 or 3 long-slender setae. Mid- and hind femora cylindrical, with 2 or 3 long-slender setae and some spike-like setae. Tarsal claws of midlegs slightly curved downwards apically, each with stout basal seta. Tarsal claws of hind legs stout, each with stout basal seta.

Abdomen. Abdominal segments I–IX covered densely with black hair-like setae and sparsely with half-erect scale-hair setae ( Fig. 10E ). Segment I ventrally with two pairs of bifid-stemmed gill; segments II–VI each with ventrolateral bifid-stemmed gill and ventromesal single-stemmed gill; segments III–VI with pupal gill buds laterally; segment VII with pair of bifid-stemmed gills. Subtriangular sterna of segments VIII and IX each with pair of ventral plates ( Fig. 10F ), brown, covered with tapered, short acuminate peg-like setae, posterior borders of these sternites with some long slender black setae. Anal prolegs ( Fig. 10G ) slightly sclerotized with spike-like setae and apical part with about 30 long slender setae arranged in one plane similar to spines of Chinese fan. Anal claws ( Fig. 10G ) yellowish brown, hook-like, angled about 90º.

Diagnosis. The larva of this species can be diagnosed by the combination of the following features: (1) the body is grayish yellow; (2) the frontoclypeal apotome has three yellow patches, the anterior one and the middle one are connected to form a mushroom-shaped pattern, the posterior one is somewhat triangular; (3) the anterior margin of the frontoclypeal apotome is slightly convex; and (4) each foretrochantin is bifurcate, with the two branches divergent at an angle of about 60º.

Material examined. Five larvae, CHINA, Yun-nan Province , He-qing County, Zhong-jiang Town , Zhong- jiang-cun, Yang-gong Jiang, 26°41’98”N, 100°44’84”E, Alt. 1196 m, 13 Aug 2019, collected by Xin-yu Ge & Yin-chang Wang ; five larvae and two males, same locality, 21 Nov 2019, collected by Chang-hai Sun & Yin-chang Wang ; eight larvae, same locality, 16 May 2020, collected by Tian-jin Sheng & Yin-chang Wang.

Notes. The larvae of H. uvana were collected in Yang-gong Jiang stream. The substrate consists of gravel, cobble and boulders. Filamentous green algae were dense, indicating water was eutrophic. The water velocity of the stream ranged between 1.6–2.5 m /s; the stream is 15–25 m wide, and 0.4–1.0 m deep. In August, the stream was turbid during high discharge.

Figures

FIGURE 8. Head of Hydropsyche uvana Mey 1995. 8A, dorsal; 8B, right lateral; 8C, ventral; 8D, right mandible, ventral; 8E, submentum, cardo, and anterior ventral apotome, ventral; 8F, maxillae and labium, ventral. Scale bars: 0.1 mm.

FIGURE 9. Thorax of Hydropsyche uvana Mey 1995. 9A, pronotum, dorsal; 9B, prosternal plates and posterior prosternal sclerites, ventral; 9C, mesonotum, dorsal; 9D, metanotum, dorsal. Scale bars: 0.1 mm.

FIGURE 10. Legs and abdomen of Hydropsyche uvana Mey 1995. 10A, right foreleg, right lateral; 10B, right propleuron, right lateral; 10C, right midleg, right lateral; 10D, right hind leg, right lateral; 10E, setae of abdominal tergum VII, left dorsolateral, red arrows indicating scale-like hairs; 10F, plates on abdominal sterna VIII and IX, ventral; 10G, anal prolegs, left lateral. Scale bars: 0.1 mm.