Arctopsyche shimianensis Gui and Yang 2000
Creators: name: Zhou, Xin
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Trichoptera
Hydropsychidae
Arctopsyche
Arctopsyche shimianensis

description: Arctopsyche shimianensis Gui and Yang, 2000
Figures 2a–l
LARVA — HEAD. Head oval, 3.1 mm long, 2.8 mm wide, dorsoventrally flattened. Frontoclypeal apotome strongly constricted opposite eyes, maximum width at anterior end. Anterior margin of frontoclypeus curved, convex in middle, smooth, without flanges or notches. Areas near tentorial pits depressed, but not connected by complete mediotransversal crease as in some species of Hydropsychinae.
Primary setae mostly long, thick and dark except seta 17 short, yellowish, and clear. Secondary setae small, fine, tapered, blackish with yellowish basal ends. Setal pits of these small hairs often large and relatively deep, posterior edge elevated and dark, anterior edge depressed and pale, giving head capsule rough appearance. No blunt-setae present on dorsum of head. Several secondary setae on anterolateral corners of frontoclypeal apotome long, curved, yellowish, and clear. Setae on posterior half of frontoclypeus sparser. Thickened spiky setae distributed on ventrolateral sides of head, short to moderately long, dark, clearly visible from dorsal, lateral, and ventral aspects.
In dorsal aspect, head mostly dark brownish, with some inconspicuous pale marks: anterior half of frontoclypeus with pair of elongated marks on lateral portions immediately anterior to depressed regions near tentorial pits; series of four round blackish dots transversely arranged on middle portion connecting lateral pale marks; bases around setae 9 yellowish; posterior half of frontoclypeus with V-shaped pale mark along posterior half of frontoclypeal suture; longitudinal pale stripe visible along mesal line of frontoclypeus and coronal suture, although often very weak; small, round, bright mark located posterior to apex of expanded portion of frontoclypeus, followed by longitudinal pale stripe along proprioceptors 19, 20, and 21 on posterior parietal sclerite of each side. Muscle scars mostly confined on posterior portion of head, often slightly paler than background, with dark borders. Lateral sides of head generally pale, yellowish, eyes each surround by whitish area. Muscle scars pale, not conspicuous. Stout spiky setae pronounced.
Parietal sclerites separated completely on ventral side by ventral apotome. Anterior end of ventral apotome enlarged; anterior margin slightly curved; both anterolateral corners acute; lateral borders narrowed gradually toward posterior end and almost parallel to each other on posterior half; posterior end of ventral apotome with small brownish triangular projection. Submentum trapezoidal, anterior and posterior borders slightly curved; anterior margin not cleft; area adjacent to posterior margin with curved transverse ridge. Outline of stridulating files wide; striae on anterior portion of stridulating files thicker than those on posterior portion; each stria consisting of series of dark brownish, horizontally arranged short bars. Muscle scars mostly confined to posterior portion of venter of head, about as dark as background, not conspicuous. Stridulating files and following area dark; ventral apotome and areas on parietal sclerites mesal of stridulating files generally pale; ridges along occipital margins pale. Setae on ventrolateral sides of head consisting of short, fine hair-like setae and moderately long, stout, spiky, dark brownish setae, with setal pits pronounced.
THORAX. Thoracic nota covered mainly by moderately long, tapered, blackish, thick and hair-like setae. Hairs on meso- and metanota generally sparser than those on pronotum. Pronotum subdivided longitudinally. Majority of pronotum dark brownish, lateral fourth of each side of notum pale, yellowish (not visible in dorsal aspect). Posterior margin bearing transverse blackish border, followed by wide yellowish area and brownish narrow sclerotized stripe. Posterior three-fourths of lateral borders blackish, anterior fourth of lateral borders and anterior margin without blackish mark. Anterior fourth of lateral borders bearing series of moderately long, thick, blunt, brownish peg-like setae; anterolateral corners of pronotum also with few similar setae (Fig. 2e, with hairs on anterolateral corner of left side of pronotum further enlarged). Hairs on anterior margin of pronotum similar to those on dorsum of notum, but longer and thicker.
Foretrochantin triangular, not forked, distal end gradually tapered into sharp apex. Dorsal surface of trochantin nearly straight, bearing two large, pointed, brownish spurs and series of blackish bristles (Fig. 2g, with foretrochantin further enlarged). Prosternal plate large, folding transversely at posterior third into almost right angle (Figs. 2f, g). Anterior margin protrusive in middle, forming acute angle. Anterior margin blackish; posterior border with wide, oblong, blackish mark in middle third. No posterior prosternal sclerites present. At least in some individuals (probably mature larvae before becoming prepupae), intermediate space between prosternal plate and ventrolateral borders of pronotum appearing sclerotized and yellowish; these sclerites appressing each other tightly and forming integrated piece (as shown in Fig. 2f).
Mesonotum paler than pronotum, mostly brownish, with longitudinal pale stripe along mid-dorsal line. Area following blackish posterior median mark pale, yellowish. Lateral half of each side of mesonotum generally pale. Transverse ecdysial line extending from posterior third of median part of notum nearly to middle of lateral borders. Anterior margin bearing heavy blackish mark, disconnected from lateral marks near anterolateral corners. In lateral aspect, mesonotum appearing triangular in sagital section, with dorsal border convex (Fig. 2e). Posterior border with blackish crescent mark on middle two-fifths. Pale areas following median mark triangular, followed by pair of brownish short bars with crenulated posterior borders. Muscle scars mostly confined on posterior portion of notum, typically paler than background. Areas near anterolateral corners of notum without peg-like setae, but with few scattered club-hairs.
Metanotum lightest among thoracic nota, dorsoventrally depressed, almost quadrate, posterior margin bearing wide, deep excision. Mostly light brownish, with longitudinal yellowish stripe along mid-dorsal line. Transverse ecdysial line bearing sharp angle pointing caudad at position immediately anterior to Sa 2 of each side. Anterior margin with blackish border, not as broad as that on mesonotum, disconnected from lateral borders near anterolateral corners. Posterior border bearing narrow, wide, blackish mark on middle threefourths, curving caudad. Mesosternum with one pair of ventral tracheal gills; metasternum bearing two pairs (ventrolateral and ventromesal) (Table 2). All thoracic gills with single, globular gill stems; each gill stem bearing 25–40 gill filaments distributed evenly on upper hemi-sphere (Fig. 2j).
Thorax Abdominal segments
ABDOMEN. Abdominal terga and pleura densely covered by long, pointed, curved hair-like setae and long, thick, dark brownish club-hairs, each with apex slightly enlarged and truncated (Fig. 2i). Club-hairs typically longer and stouter than hair-like setae. Club-hairs not forming clusters. Abdominal pleura II–VII with large lateral (pleural) gills posteroventrally on each pleuron: II and VII with one gill; III–VI with two gills on each side; I, VIII and IX without lateral gills (Table 2; Fig. 2l). Lateral gills similar to ventral gills, only smaller; each gill with single cylindrical stalk; numerous gill filaments arising mostly from apex of each stalk. Lateral gills not covered by abdominal hairs.
Abdominal sterna bearing two types of ventral gills: single-stemmed gills and bifid-stemmed gills, with single-stemmed gills typically situated anteromesal of bifid- stemmed gills when both present on particular segment. Gill filaments arising from apex of each gill stem or each branch of bifid gill stem. Abdominal segment I with pair of single-stemmed ventral gills (ventrolateral and ventromesal) on each side, isolated from each other; II–V each with one single-stemmed ventromesal gill and one bifid-stemmed ventrolateral gill on each side (Fig. 2k); VI with only one bifid-stemmed ventrolateral gill on each side; VII with two singlestemmed gills on each side; VIII and IX without ventral gills (Table 2).
Sterna VIII and IX each bearing strongly sclerotized yellowish plates: ventral plate VIII relatively small, fused into one single piece, nearly trapezoidal, posterior border longer, bearing small median notch; ventral plates IX large, separated, each nearly trapezoidal, with mesal border longer, posteromesal corner slightly acute. Anterior half of plate VIII bearing almost no hairs; posterior half with series of short, thick, peg-like, golden setae, whose setal sockets pronounced; posterior border with row of thick (about as thick as peg-like setae), long, blackish bristles. Plates IX large, lateral portions folding dorsad toward pleura; anterolateral corner of each plate IX bearing almost no hairs; remaider of each plate with several short (longer than those on plate VIII), thick, golden, peg-like setae and short, thin, tapered, hair-like setae; posterior border of each plate IX bearing dense row of long, thick, blackish bristles pointing caudad; longitudinal area between plates IX bearing series of short, fine, tapered, blackish hair-like setae (Fig. 2h).
Diagnosis. The mature larva of A. shimianensis is a very large caddis. The head is typically wide and dorsoventrally depressed. Most of the dorsum of the head is dark, with slightly pale marks, which can be very inconspicuous in some individuals. The stridulating files on the ventral side of the head are pronounced. The thick, spiky setae on the ventrolateral side of the head and the hairs on the anterolateral corners of both the pro- and mesonota appear to be diagnostic for the species. Each of the bifid-stemmed ventrolateral gills on abdominal pleura VI can be two separate single-stemmed gills that are very close together.
Material examined. Sichuan: Mian-ning County, Jia-wu-cun Village. Yan-jian-gou stream, 100–150 m upstream of S215 at 410.4 km stone marker. N28.36409, E101.99700. 2379 m. 3-July-2005. X. Zhou, C-F Zhou, 13 specimens. Zhao-jue County, Jie-fang-cun Village. Jie-fang-gou stream, S307 at 553.0 km stone marker. N27.88159, E102.55734. 2925 m. 4-Jul-2005. X. Zhou, C-F Zhou, 36 specimens.
description: Published as part of Zhou, Xin, 2009, The larvae of Chinese Hydropsychidae (Insecta: Trichoptera), Part I: Arctopsyche shimianensis, Parapsyche sp. A, and Diplectrona obscura, pp. 1-17 in Zootaxa 2174 on pages 6-9, DOI: 10.5281/zenodo.189300