Cryptotendipes

Yan, Chuncai, Tang, Hongqu & Wang, Xinhua, 2005, A review of the genus Cryptotendipes Lenz (Diptera: Chironomidae) from China, Zootaxa 1086, pp. 1-24 : 13-15

Cryptotendipes sp. 2 ( Fig. 6 A–E)

Material examined: 5 larvae. CHINA: Jiangsu Province, Suzhou City, Chenghu Lake, 7. IV.1983, leg. J. Yan.

Fourth­instar larva

Total length 6.20–6.35, 6.28 mm, head capsule 300–350, 317 µm long, 270–280, 277 µm wide, cephalic index 0.82–0.93, 0.89.

Coloration ( Fig. 6 A): Head capsule yellowish brown. Mentum teeth dark brown. Only ventral median part of posterior occipital margin dark brown. Gula area pale brown.

Antenna ( Fig. 6 Bc): Total length 65–68, 66 µm long, 0.19–0.22, 0.21 times as long as head capsule, 0.57–0.60, 0.58 as long as mandible. Lengths of segments (in µm): 35–37.5, 37; 10–12, 11; 2–3, 2.5; 4–4.5, 4; 4.5–5, 5. AR = 1.32–1.37, 1.36. Basal segment 15–17.5, 17 µm wide. Basal segment ratio 2.0–2.5, 2.21; antennal blade 24–26, 25 µm long, reaching apex of fifth segment, accessory blade 17–20, 18 µm long, extending to apex of fourth segment. Ring organ located at 0.40–0.55, 0. 50 of basal segment, distance from base17.5–20, 18 µm. Style strongly developed, 6–8, 7.5 µm long, reaching middle of 4th segment. Lauterborn organ absent.

Labrum: SI and SII blade­like, SI 25–30, 28 µm long, SII 35–38, 36 µm long. SIII simple; SIVA consists of 2 segments, segment ratio about 3:2. With 5 pairs of chaetulae laterales and 3 pairs of chaetulae basales. Pecten epipharyngis ( Fig. 6 Ba) a simple, distally trifid plate. Premandible 70–75, 72 µm long, with 2 pointed apical teeth and 1 blunt basal tooth. Premandible brush present. Anterior margin of frontal apotome straight, with S3 located in each corner. SL1 and SL2 well developed, Sl at posterior margin of SL1. SL3 present on each side, other sclerites absent ( Fig. 6 D).

Mandible ( Fig. 6 C): Total length 105–113, 108 µm long. Distal part brown, basal part pale. With 2 inner teeth and 1 apical tooth, third false teeth present on mola. Apex of mandible teeth triangular, not flat. Seta subdentalis blade­like, strongly developed, 37–40, 39 µm long, extending to base of apical tooth. Seta interna with 4 branches, third distally subdivided, others simple.

Mentum ( Fig. 6 E): Total length 95–108, 101 µm. Median tooth without distinct lateral notch, 27.5–30, 28 µm wide. Outer 3 lateral teeth fused into compound tooth, occasionally fourth laterals submerged into enlarged fifth laterals. Ventromental plate 85–88, 86 µm wide (w), 30–38, 35 µm long (l). Separation between plates 50–55, 52 µm. VmPR (w/l): 2.50–2.83, 2.72; VmPSR (w/s): 1.59–1.70, 1.63; Mentum ratio (VmP/M): 0.88–0.92, 0.90. Striae number 16–18. Setae submenti simple, distance between 58–65, 61 µm. Postmentum 135–140, 138 µm long.

Maxilla: as in Fig. 6 Bb.

Abdomen: Posterior parapods 200–220, 210 µm long, 115–125, 120 µm wide, with 16 yellow simple claws. Anal tubules conical, dorsal pair 70 µm long, 40 µm wide at base; ventral pair 80 µm long, 50 µm wide at base. Procercus 20–25, 22 µm high, 25–28, 27 µm wide. Procercus ratio 0.87–0.94, 0.91, with 8 anal seta, each 565–580, 575 µm long, with 2 small subapical anal setae, 75–90, 86 µm long. Supraanal seta 360–380, 378 µm long.

Remarks: The larva resembles that of C. usmaensis from Germany. Both have the dome­shaped median tooth without a distinct lateral notch and the mandible with triangular inner teeth hardly extending from the inner margin. Small differences exist in the lengths of the seta subdentalis and the third antennal segment. The seta subdentalis is relatively long, distinctly extending to the base of the apical teeth, and the third antennal segment is about half as long as the fourth segment, whereas in C. usmaensis , the seta subdentalis only extends to the basal inner tooth and the third antennal segment is much longer than the fourth segment. According to Pagast (1931: 221), the ratios between antennal segments are 42: 12: 6: 4.5: 4.5, whereas in our material they are 45: 12: 3: 6: 6. Cryptotendipes sp. 2 can be separated from C. sp.1 by the triangular inner mandible teeth and the weak pigmentation of the postmentum and the posterior occipital margin. We cannot associate this larva with any adult and, thus, tentatively refer to it as C. sp. 2.

Figures

FIGURE 6. Cryptotendipes sp. 2. Fourth­instar larva. A. Gula and posterior occipital margin. B. Pecten epipharyngis (a); maxillary palp (b); antenna (c). C. Mandible. D. Frontal apotome and sclerites. E. Mentum.