Anabolia appendix, (Ulmer 1905) (Ulmer, 1905)

Deng, Zhen, Zang, Haoming, Wang, Meng & Sun, Changhai, 2024, The larva and pupa of Anabolia appendix (Ulmer 1905) (Trichoptera: Limnephilidae) from China, Zootaxa 5529 (1), pp. 93-109 : 96-108

Larva (5th instar):

Body length 12.4–15.5 (13.8 ± 1.1) mm (n = 6). Head, pronotum and mesonotum yellow to brownish yellow, with randomly distributed dark brown muscle scars. Legs pale yellow to dark brown. Dorsal sclerite of segment IX pale yellow. Anal claws dark brown.

Head: Head capsule brown with irregularly distributed, discrete, dark brown muscle scars as shown in Fig. 3 . Dorsum of head ( Fig. 3A ) ovoid, 1.84–2.02 (1.92 ± 0.07) mm long, 1.27–1.39 (1.33 ± 0.05) mm wide (n = 6). Frontoclypeal apotome with one pair of round muscle scars anteriorly near bases of setae number 3, one pair of black ones at mid-length angles (on tentorial pits near setae number 5), one pair of small submesal ones between and anterior of setae number 5 and two black muscle scars abovementioned, and wedge-shaped cluster of muscle scars positioned posteriorly and tapering anteriorly. Parietals with many dark muscle scars, some of them arranged in lines, especially posterodorsally near median ecdysial line and behind eyes. Frontoclypeal suture somewhat Ʊshaped, curved at tentorial pits near setae 5 at angle of about 110°, and near setae number 4 at angle of about 100°. In lateral view ( Fig. 3B ) subelliptical, with posteroventral occipital margin incised at angle of about 140°. In ventral view ( Fig. 3C ) subelliptical, with posterior margin having deep V-shaped incision; ventral apotome (vap) bellshaped, with margins dark brown; ventral ecdysial line about two-thirds as long as vap. Setae ( Fig. 3D ) 5, 9, and 13 thicker and longer than other setae; setae 11 and 14 shortest; setae 1, 2, 3, 7, 12, 15, and 17 subequal in length; setae 4, 10, and 16 slightly longer than setae 11 and 14; setae 8 and 18 represented in our specimens only by sensory pits (or alveoli?). Clypeus ( Fig. 3A ) trapezoid, yellow, about four times as wide as long and with anterior margin slightly concave. Eyes ( Figs 3A, 3B ) oval, brown, each surrounded by faint yellow halo. Antennae ( Fig. 3A ) positioned midway between eyes and mandibles, each two-segmented, basal joint stout, distal one tiny and slightly curved.

Labrum ( Figs 3A, 3D ) semi-circular, dark brown, with 6 pairs of yellow setae, seta 1 shortest, seta 5, 6 longer than other setae, setae 1–3 situated on anterior margin, setae 4–6 triangularly arranged on anteromedial portion of labrum, pair of hair brushes at anterolateral corners. Mandibles ( Figs 3E–3H ) subtriangular, black, asymmetrical in shape, each with four teeth on distal margin, outer side with two setae basally, and inner side with setal brush mesally.

Maxillae ( Fig. 3C ) in ventral view each with cardo subquadrilateral, black basally and apically, middle portion pale yellow to brown; stipes subrectangular, each with basomesal angle produced outwards with each anterior margin having short mesal seta and long lateral seta; palpifers subrectangular, each with long hair-like seta and short peg-like seta anteriorly; maxillary palpi each four-segmented, setose on outer margin, tapering from base to apex, lacinia-galea elliptical, each with inner margin bearing cluster of fine hairs.

Labium ( Fig. 3C ) in ventral view with submental sclerites slightly sclerotized and fused, anterior portion with two dark brown U-shaped dark spots, each with one strong mesal seta; mentum U-shaped, black; ventral rod slender. bar-shaped, brown, each with peg-like seta anteriorly; palpiger somewhat V-shaped, brown, each with alveolus mesally; labial palpi each 2-segmented, cylindrical.

Thorax: Pronotum ( Fig. 4A ) subrectangular, strongly setose, pale yellow dorsally, subdivided longitudinally by mid-dorsal ecdysial line, with brown transverse depression dorsally about one third distance from anterior margin; irregular dark muscle scars scattered between posterior margin and transverse depression; posterior ridge pale yellow to dark brown. Prosternal horn ( Fig. 4B ) brown, slender, and slightly curved. Prosternite ( Fig. 4C ) subpentagonal, brown, each anterolateral corner extended into lobe, and posterior margin concave mesally. Paired lateral prosternites ( Fig. 4C ) irregular and asymmetrical.

Mesonotum ( Fig. 4D ) subrectangular, brownish yellow, subdivided longitudinally by mid-dorsal ecdysial line in dorsal view, with long hair-like setae, short peg-like setae and dark brown muscle scars; W-shaped transverse pattern issuing from each anterolateral conner and extended mesad to ecdysial line. Posterolateral corners each with black spot; fine posterior margin black. Mesosternum ( Fig. 4E ) membranous, with two pairs of clusters of small brown sclerites posteriorly irregular in number, distribution, and shape.

Metanotum ( Fig. 4F ) membranous, sa1 sclerites nearly ovoid, transversely oriented, close to each other, each with 5–8 setae; sa2 sclerites subcircular, each with 4–5 setae, sa3 sclerites ( Fig. 4G ) subrectangular, with 15– 20 setae anteriorly. Metasternum ( Fig. 4H ) membranous, with submesal pair of clusters of small brown sclerites posteriorly irregular in number, distribution, and shape, with sclerites of sublateral pair less distinctly defined than those of submesal pair.

Legs: Forecoxae ( Figs 5A, 5B ) each subtrapezoidal, setose, about twice as long as broad, in anterior view with dark brown spots arranged in L-shaped pattern, in posterior view with dark brown spots basally, dark margin apically. Foretrochanters each 2-segmented, in anterior view, basal subsegment triangular, apical one trapezoidal and longer than basal one; in posterior view both subsegments triangular; basal subsegment with 0–2 setae anteriorly, apical subsegment with lower margin having 3 hair-like setae, 2 spur-like setae, trochanteral brush distally. Forefemora each subrectangular, with upper margin longer than lower margin; in anterior view, arc-shaped spots arranged on middle of upper margin and extending to base of lower margin; in posterior view, with only 4 spots near middle of upper margin, upper margin with 6 or 7 setae, and lower margin bearing row of teeth with two major setae, sub-basal seta yellow and slightly shorter than spur-like seta near middle of margin. Foretibiae each cylindrical, about half as long as femur, slightly curved ventrad at base, lower margin dentate and with 2 yellow apical spurs. Foretarsi each cylindrical, short, with pair of hair-like setae apically. Foretarsal claws cylindrical, tapering to acute apices, and slightly curved downwards, each with basoventral seta.

Mid- and hind legs ( Fig. 5C–5F ) similar in shape to forelegs, but longer and slenderer. Coxae about three times as long as thick. Trochanters each 2-segmented, basal subsegment with 0–2 setae, apical subsegment with 2–6 setae, and apical subsegment of each hind trochanter having 1 yellow spur-like setae distally. Midfemora each with lower margin having 2 spur-like major femoral setae, one near middle and one near base, middle yellow seta thicker than sub-basal dark brown seta. Hind leg major femoral setae on ventral margin near middle and subapically, middle setae yellow, spur-like and shorter than subapical dark hair-like seta. Mid- and hind tibiae each with 5–7 setae.

Abdomen: Abdominal segment Ⅰ ( Figs 6A–6C ) with about 70–80 setae dorsally and ventrally, with one dorsal and two lateral humps, lateral humps each with one dorsal seta. Abdominal segments III to VIII with lateral fringes present ( Fig. 7A ). Tracheal gills trifid, bifid, or unbranched ( Figs 6D–6S ). Abdominal segment II to VII ( Figs 6F–6S ) with long elliptical ventral chloride epithelia and round lateral chloride epithelia, with chloride epithelia of segment II smaller than those of segments III–VII; abdominal terga III to VII with elliptical dorsal chloride epithelia. Dorsal sclerite of segment IX ( Fig. 7B ) elliptical, light brown, with 9 hair-like setae, lateral and submesal pairs of setae black, longer, and thicker than 5 other setae. Abdominal segment X ( Fig. 7C ) with lateral sclerites elongate-elliptical, setose, each with its basolateral angle protruding ventrad; ventral sole plate triangular and its dorsolateral margin black; one accessory hook short and at outer angle of anal claw, this claw curved about 90°; basal tufts each composed of 2 strong bristles and 1 slender lateral seta. Number and distribution of gill filaments of final instar larva of A. appendix given in Table 3 .

Case: Case ( Fig. 8 ) tubular, straight or slightly curved, with posterior apex slightly narrower, mainly made of sand grains and mineral particles, with few cases containing plant and detrital material.

Pupa: Length 12.8–14.6 (13.5 ± 0.7) mm (n = 5). Body ( Fig. 9 ) pale yellow to brown (in alcohol).

Head: Pale yellow; frons subtrapezoid in dorsal view ( Figs 10A, 10B ), with one pair of long, dark setae and one pair short, dark seta along sinuate anterior margin; clypeus subrectangular, postclypeus yellow, anteclypeus pale yellow, each anterolateral angle with 3 strong setae; vertex in dorsal view subrectangular, with each posterolateral angle having short weak seta. Eyes ( Fig. 10B ) reddish brown. Antennae ( Figs 10A , 9B ) filiform, shorter than body, each antennal scape with ventral antennal tuft of 1 or 2 setae and dorsal antennal tuft of 3–4 setae, antennal pedicel with ventral antennal tuft of 4–6 setae. Labrum ( Fig. 10B ) semicircular, dark brown, with each anterolateral angle pale yellow and with 5 strong, apically hooked setae. Mandibles ( Fig. 10C ) dark brown, each with basal portion stout and elliptical and laterally with one strong seta and one short peg-like seta, apical portion elongate-triangular with sharp apex. Maxillary palpi 3-segmented in males ( Fig. 10D ), first segment shortest, second and third segments equal in length; 5-segmented in female ( Fig. 10E ), first segment shortest, other segments equal in length. Labial palpi 3-segmented in both sexes, third segment longer than others.

Thorax: Wing sheaths ( Fig. 9B ) with apices extending to posterior edge of abdominal segment III. Forelegs shortest, hind legs longest ( Figs 11A–11F ), spurs 2-4-4, mid- and hind tarsi Ⅰ–IV ( Figs 11G, 11H ) each bearing many lateral and mesal hair-like setae to facilitate swimming to the surface for emergence.

Abdomen: Lateral fringes ( Figs 12K–12P , 13A–13C ) distributed on posterolateral margins of segment Ⅴ to posteroventral margins of segment VIII. Terga VI–IX and sterna V–VIII scattered with dark brown spots. Anterior pair of dorsal hook plates ( Figs 12E, 12H, 12K 12M, 12O ) on terga III–VII, each with 3–6 strong hooks; IIIa subround, smaller than other anterior hook plates; IVa, Ⅴa, and VIa subelliptical; VIIa papillate; IVa, Ⅴa, VIa, and VIIa subequal in size. Tergites I and V with paired posterior dorsal hook plates ( Figs 12A, 12M ); Ip each transversely elongate, with many short, stout hooks; Vp each subrectangular, bearing 10–11 stubby hooks. Hook numbers on each hook plate as follows: Ip 6 or 7; IIIa 3 or 4; IVa 3–5; Ⅴa 5 or 6; Ⅴp 10 or 11; VIa 4 or 5; VIIa 4 or 5. Anal appendages ( Fig. 12Q ) yellowish brown, slender, with 2 pairs of long hair-like setae basally, 1 pair of long setae subapically, 1 pair of short setae apically, subapex curved outwards. Gill filament numbers and their arrangement are given in Table 4 .

Diagnosis

Larva: The larva of A. appendix can be distinguished from those of other Anabolia species by the following combination of characters:(1) on the frontoclypeal apotome there is 1 pair of round muscle scars near the anterolateral margins and 1 pair of black ones are at the angles of the tentorial pits; (2) the parietals have few muscle scars; (3) a few brown muscle scars are in the anterior transverse depression of the pronotum; (4) each forefemur has its major femoral seta near mid-length slightly longer than the sub-basal seta; (5) the anterior side of the basal subsegment of each foretrochanter has 0–2 setae; (6) the major femoral seta of each hind leg is located in the subapical and middle portions of the femur, and the subapical seta is longer than the middle one.

Pupa: Pupae of this species can be diagnosed by the shapes of the abdominal hook plates and their hook numbers, and by the setal numbers of the frontoclypeus and labrum.

Material examined: 5 females: China, Gan-su Province , Ding-xi County, Xin-si Town , Hei-hu Forest Farm , 34°37′37″N, 104°50′29″E, Alt. 1756 m, 23 Aug 2021, collected by Haoming Zang ; 7 larvae and 10 pupae: China, Qing-hai Province , Hai-bei Tibetan Autonomous Prefecture , Qi-lian County, Qing-yang Gou, 38°11′14″N, 100°24′51″E, Alt. 3377 m, 31 Jul 2022, collected by Haoming Zang & Cong Li ; 3 larvae: China, Qing-hai Province , Hai-xi Mongolian and Tibetan Autonomous Prefecture , Tian-jun County, Su-ri Township, 38°41′38″N, 98°00′32″E, Alt. 3611 m, 30 Jul 2022, collected by Haoming Zang.

Figures

FIGURE 3. Head of Anabolia appendix (Ulmer 1905), fifth instar larva. 3A, dorsal (left eye and antenna in inset); 3B, left lateral; 3C, ventral; 3D, primary setae on dorsal surface; 3E, right mandible, ventral; 3F, right mandible, mesal; 3G, right mandible, dorsal; 3H, right mandible, mesal view. vap. = ventral apotome; car. = cardo. Scale bars: 1 mm.

FIGURE 4. Thorax of Anabolia appendix (Ulmer 1905), fifth instar larva. 4A, pronotum, dorsal; 4B, pronotum, left lateral; 4C, prosternum, ventral; 4D, mesonotum, dorsal; 4E, mesosternum, ventral; 4F, metanotum, dorsal; 4G, metanotum, setal area 3, right lateral; 4H, metasternum, ventral. Scale bars: 1 mm (except 4C), 4C = 0.1 mm.

FIGURE 5. Legs of Anabolia appendix (Ulmer 1905), fifth instar larva. 5A, right foreleg, anterior; 5B, right foreleg, posterior; 5C, right midleg, anterior; 5D, right midleg, posterior; 5E, left hind leg, anterior; 5F, left hind leg, posterior. Scale bars: 1 mm.

FIGURE 6. Abdomen of Anabolia appendix (Ulmer 1905), fifth instar larva. 6A, 6D, 6G, 6J, 6M, 6P, 6R, terga of segments Ⅰ–VII, respectively; 6B, 6E, 6H, 6K, 6N, pleura of segments Ⅰ–Ⅴ, respectively; 6C, 6F, 6I, 6L, 6O, 6Q, 6S, sterna of segments Ⅰ–VIII, respectively. Scale bars: 1 mm.

FIGURE 7. Abdomen and anal prolegs of Anabolia appendix (Ulmer 1905), fifth instar larva. 7A, lateral fringe of abdomen, right lateral; 7B, abdominal segments IX and X and anal prolegs, dorsal; 7C, right anal proleg, right lateral. Scale bars: 1 mm.

FIGURE 8. Cases of Anabolia appendix (Ulmer 1905), fifth instar larva. 8A, case constructed of plant fragments and detrital particles; 8B, case constructed of sand grains and mineral particles. Scale bars: 1 mm.

FIGURE 9. Body of Anabolia appendix (Ulmer 1905) pupa. 9A, dorsal; 9B, ventral. Scale bars: 1 mm.

FIGURE 10. Head of Anabolia appendix (Ulmer 1905) pupa. 10A, head, dorsal; 10B, labrum, dorsal; 10C, mandibles, ventral; 10D, maxillary and labial palps, male, ventral; 10E, maxillary and labial palps, female, ventral. Scale bars: 1 mm.

FIGURE 11. Legs of Anabolia appendix (Ulmer 1905) pupa. 11A, left foreleg, posterior; 11B, left foreleg, anterior; 11C, left midleg, posterior; 11D, left midleg, anterior; 11E, right hind leg, anterior; 11F, right hind leg, posterior; 11G, right midtarsus, posterior; 11H, right hind tarsus, posterior. Scale bars: 1 mm.

FIGURE 12. Abdomen and anal appendages of Anabolia appendix (Ulmer 1905) pupa. 12A, 12B, 12E, 12H, 12K, 12M, 12O, terga of segments Ⅰ–VII, respectively; 12C, 12F, 12I, right pleura of segments II–IV, respectively; 12D, 12G, 12J, 12L, 12N, 12P, sterna of segments II–VII, respectively; 12Q, anal appendages, dorsal. Scale bars: 1 mm.

FIGURE 13. Abdomen of Anabolia appendix (Ulmer 1905), pupa. 13A, dorsal; 13B, right lateral; 13C, ventral. Scale bars: 1 mm.