Hydromanicus melli ( Ulmer 1926 )

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 : 532-535

publication ID	https://doi.org/ 10.11646/zootaxa.5026.4.4
publication LSID	lsid:zoobank.org:pub:B9D78F3F-240D-4278-9FAF-6EB5C19083C5
DOI	https://doi.org/10.5281/zenodo.5307807
persistent identifier	https://treatment.plazi.org/id/03BE1706-BE3B-FFD0-1498-4164FD5CFD97
treatment provided by	Plazi
scientific name	Hydromanicus melli ( Ulmer 1926 )
status

Treatment

Hydromanicus melli ( Ulmer 1926)

( Figs 2a–2l View FIGURE 2 )

HEAD. Head quadrate, 2.1 mm long, 1.7 mm wide. In dorsal aspect ( Fig. 2b View FIGURE 2 ), majority of head capsule chestnut brown, with each eye circled by creamy yellowish, round mark, posterior parietals light-colored. Muscle scars, mostly confined to posterior part of dorsum of head, darker or paler than background. Coronal suture curved posteriorly to left. Frontoclypeal apotome narrowed near tentorial pits, maximum width at extreme anterior end. Anterior margin of frontoclypeal apotome asymmetrical, deeply excised, each subanterolateral corner with one large emargination, left emargination wider and deeper than right one. Anterior margin of frontoclypeus lateral to right emargination tooth-like, being most-distal on anterior margin. Medium convexity of anterior margin between two large emarginations of frontoclypeus often crenulated, with series of small flanges (more or less truncate in some individuals). Left anterolateral corner of frontoclypeus with oblique, elevated ridge, extending from near left eye to approximately left third of anterior margin of frontoclypeus, aligned with convex slope of crenulated portion of anterior edge. Regions near tentorial pits slightly depressed. Secondary truncate-peg setae ( Schefter & Wiggins 1986) few, short to moderately long, black, stout, with blunt apices, all confined near anterior margins of frontoclypeus and parietals. Head generally glabrous-looking, with pale, minute, seta-less pits scattered over most of dorsum. Series of five larger, light-colored pits easily identifiable on parietal sclerite of each side, longitudinally arranged: only second pit from anterior end bearing setae (seta 17); last three pits (proprioceptors 19, 20 and 21) on posterior parietal tightly and evenly spaced. Two setae situated very closely next to each other at setal position 17 [chaetotaxy following Williams and Wiggins (1981); Schefter and Wiggins (1986); Wiggins (1996)], giving appearance of sharing single setal socket: one (17a) situated anterolaterally, long, thin, tapered, pale and transparent; second one (17b) situated posteromesally, less than 2/3 as long as other seta, blunt, yellowish and semitransparent.

Stridulating files on ventral side of head rectangular in outline, with very long, straight longitudinal and narrowed transverse outlines ( Fig. 2c View FIGURE 2 ). Stridulating file area lighter in color than remainder of head. Anterior ventral apotome not darker than remainder of head, generally triangular, with anterior margin slightly concave and both subanterolateral corners slightly angled. Posterior ventral apotome minute, triangular. Submentum trapezoidal, with concave anterior and convex posterior borders parallel.

Upper blade of left mandible with two apical teeth dorsoventrally arranged, dorsal one small and blunt in some individuals. Lower blade of left mandible with one large apical tooth, its mesal edge with three large subapical teeth and one truncate basal tooth. Dorsum of left mandible with tuft of golden setae at midlength. Right mandible with one large apical tooth on each upper and lower blade, its mesal edge with three large teeth. Each mandible with series of stout setae on outer ridge, long slender setae tapered, golden and semitransparent, shorter acuminate-peg setae blunt and black.

THORAX. Thoracic nota chestnut brown, covered with inconspicuous short, golden, tapered, transparent, secondary, acuminate-peg setae, pointing anterad. Thoracic nota generally glabrous, with shiny appearance under microscopic illumination. Pronotum subdivided longitudinally, uniformly brown, lacking marks. Small, pale pits observable in dorsal aspect, only most-mesal pit on each side with short, transparent, yellowish acuminate-peg seta. Unlike in larvae of known Chinese Hydropsyche s. l. species, thoracic seta 22 [chaetotaxy following Williams and Wiggins (1981); Schefter and Wiggins (1986); Wiggins (1996)] on each anterolateral corner of pronotum prominent in Hydromanicus larva, long and tapered, easily identifiable in dorsal aspect. Anterior border of pronotum bearing series of short, semitransparent, secondary, acuminate-peg setae; lateral and subposterior borders black; posterior edge crenulate. Sub-basal surface of pronotum slightly constricted in dorsal and lateral aspects.

Transverse prosternal plate constricted in posterior third, anterior border and middle two thirds of posterior border black. Posterior prosternal sclerites with four small sclerites transversely arranged, mesal pair subrectangular, lateral pair somewhat parallelogram-shaped; mesal sclerites generally darker than lateral sclerites; anterior margin of each mesal sclerite darker than remainder of sclerite; anterolateral corner of each lateral sclerite slightly darker than remainder of sclerite ( Fig. 2i View FIGURE 2 ).

Mesonotum with diagonal groove extending halfway from each anterolateral corner toward posterior midline; small dark spots in irregular line anteromesal of groove; surface of mesonotum posterolateral of diagonal groove elevated. Posteromesal border of mesonotum with transverse black mark in middle half, wide and curved, with lateral angles bent posterolaterad. Anterior 1/3 of mesonotum with seven pale, seta-less pits, transversely arranged in semicircular arc.

Metanotum yellowish brown, lighter than pro- and mesonota, less convex dorsoventrally than mesonotum. Metanotum with dark groove extending halfway from each anterolateral corner toward posterior midline; surface of metanotum posterolateral of diagonal groove elevated. Anterior 1/3 of metanotum with three pale, seta-less pits transversely arranged in semicircular arc. Posteromesal border of metanotum with narrow, black mark of irregular shape.

Forelegs with foretrochantins forked, dorsal branch seta-less, ventral branch with stout, dark bristles basally; dorsal branch of each foretrochantin about one and half times as long as ventral branch, about half as wide basally as ventral branch in lateral aspect ( Fig. 2e View FIGURE 2 , right inset). Lateroventral surfaces of forecoxae covered by dense, short, golden secondary setae. Ventral edges of foretrochanters and forefemora with dense rows of long, stout, dark primary setae, three primary setae on venter of distal foretrochanter very long; ventral surfaces of foretrochanters and forefemora also with shorter, golden, semitransparent secondary setae; mesodorsal surface of each forefemur with prominent protuberance, presumably functioning as scraper for stridulating ( Fig. 2e View FIGURE 2 , left inset). Venter of each foretibia with row of four stout, short, tapered, golden setae. Foretarsal claws each with small, basal, golden bristle.

Midlegs and hind legs ( Fig. 2f View FIGURE 2 ) generally similar, covered by golden, semitransparent secondary setae. Secondary setae on lateroventral side of each hind coxa sparser than those on forecoxae. Ventrodistal edge of each hind coxa with long, stout, black setae. Ventrodistal edge of each hind trochanter with long, stout, brownish seta. Posterolateral side of each hind femur with irregular median line of brownish, short, conical spines; distal and proximal ends of posterolateral side of each hind tibia also with irregular median line of similar spines, and posterolateral side of each hind tarsus at midlength also with few similar but smaller conical spines.

Mesosternum, metasternum, mesopleura, and metapleura covered by dense, short, black setae.

Gills of all thoracic sterna each with single central stalk pointing posterad. Mesosterna with one pair of ventral gills ( Fig. 2k View FIGURE 2 ). Metasterna with two pairs of ventral gills, mesal ones situated very close to each other.

ABDOMEN. Abdomen greenish when alive. Dorsum of abdominal segments covered by two types of setae: short, thin, tapered, dark hair-like setae (clothing hairs), slightly curved at distal end, generally pointing posterad and close to body surface; and longer, blunt, thicker, erect or semi-erect scale hairs ( Schefter & Wiggins 1986). Lateral gills (pleural gills) simple, finger-like or conical: abdominal segment III with one, segments IV– VI with three, VII with two; no lateral gills on I, II, and VIII – IX ( Table 2) .

Abdominal ventral gills each with elongate central stalk (single-stalked gills, as in Fig. 2k View FIGURE 2 or basally bifid elongate stalk (bifid gills, Fig. 2j View FIGURE 2 ), stalks constricted once or twice along length, appearing 2- or 3-segmented. Gill filaments arising laterally along entire length of stalk, but distal end of each stalk “segment” with somewhat more dense lateral filaments. Filaments of abdominal gills generally slender and long, giving ventral gills bushy appearance ( Fig. 2a View FIGURE 2 ). Abdominal sternum I with one pair of basally bifid ventral gills ( Fig. 2j View FIGURE 2 ); sterna II–VI each with two pairs of ventral gills: mesal pair each with single central stalk, slightly closer to mesal line and anterior of lateral pair; lateral pairs each with basally bifid central stalk. No ventral gills on sterna VII–IX.

Sterna VIII and IX each with one pair of yellowish ventral plates. Plates of sternum VIII triangular, anterior part of each with yellowish brown, tapered, short acuminate-peg setae, posterior border bearing series of dark, long, tapered, stout spike-like setae. Plates IX subtriangular, with pattern of setation similar to plates VIII, except stripe on posterior half adjacent to mesal border seta-less ( Fig. 2l View FIGURE 2 ).

Anal prolegs long, lateral sclerites light-colored. Distal end of each proleg with tuft of long, dark, thick setae; these setal tufts not very dense, without fan-like appearance. Four pale anal gills often not everted, or only partially everted.

Diagnosis. The larvae of a number of cryptic taxa within the H. melli Complex cannot currently be differentiated from one another based on morphology. The larval characteristics described here represent at least the larval forms of H. melli and the undescribed H. sp., while no larva of H. huapingensis has been sequenced and H. sp. has not yet been associated for lack of male specimens.