Cryptotendipes

Yan, Chuncai, Tang, Hongqu & Wang, Xinhua, 2005, A review of the genus Cryptotendipes Lenz (Diptera: Chironomidae) from China, Zootaxa 1086, pp. 1-24 : 11-12

Cryptotendipes sp. 1 ( Fig. 5 A–F)

Material examined: 1 larva. CHINA, Liaoning Province, Benxi City, Hunjiang Reservoir, X.1986, leg. J. Wang.

Fourth­instar larva.

Total length 3.92 mm, head capsule in several parts, lengths and widths estimated at about 300 µm long, 260 µm wide, cephalic index 0.86.

Coloration ( Fig.5 A): Head yellowish brown. Mentum and posterior occipital area dark brown. Gula pale brown.

Antenna ( Fig. 5 B): Total length 50 µm long, 0.16 times length of head capsule, 0.5 times of mandible. Flagellomere lengths as: 25; 7.5; 2; 4; 4. AR = 1.00–1.04. Basal segment relatively short, 15 µm wide. Antennal blade 17.5 µm long, reaching middle of 4th segment, accessory blade 14 µm long, extending base of 4th segment. Ring organ located near middle, 12–13 µm long from base. Style on apex of second segment, 4 µm long, extending to third segment. Lauterborn organ absent.

Labrum ( Fig. 5 C): SI and SII both slender, SII 30 µm long, SI 20 µm long. SIII simple; SIVA consists of 2 segments, basal segment 10 µm long, distal segment 5 µm long. Chaetulae laterales 5 pairs of simple setae. Pecten epipharyngis transparent, not distinct, apparently 3 blunt teeth with common base. Basal sclerite rounded. Premandible with 2 pointed apical teeth, outer tooth very slender, and 1 blunt basal tooth slightly concave in middle. Premandible brush present. Labral sclerites too indistinct to interpret.

Mandible ( Fig. 5 D): Total length 100 µm long. Distally pale brown, basally pale. With 2 inner teeth and 1 apical tooth, third false teeth present on mola. Apical tooth 12.5 µm long, about as long as combined width of 2 inner teeth. Apex of mandible teeth flat, lining up with inner margin of apical tooth. Seta subdentalis blade­like, relatively long, 35 µm, extending to base of apical tooth. Seta interna with 4 branches, first, second and fourth branches simple; distal part of third branch split into 3 or 4 small setae, basal branch longest, other branches subequal in length.

Maxilla. ( Fig. 5 E): Basal segment of maxillary palp slightly longer than wide, with ring organ located near middle. Distal part with 4 or 5 blade­like setae.

Mentum ( Fig. 5 F): Total width 95 µm. Median tooth trifid, 25 µm wide. Lateral notch not deep. Ventromental plate 75 µm wide (w), 35 µm long (l). Separation (s) between plates 52 µm. VmPR (w/l): 2.14; VmPSR (w/s): 1.44; Mentum ratio (VmP/M): 0.79. Outer margin of ventromental plate rugose. Striae number 18–20. Setae submenti simple, distance between setae 58 µm. Postmentum 118 µm long.

Abdomen: Posterior parapods 170 µm long, 90 µm wide, with 16 yellow simple claws. Anal tubules 2 pairs, dorsal pair 64 µm long and 30 µm wide; ventral pair slightly larger, 70 µm long and 45 µm wide. Procercus with 6 anal seta, 460–480 µm long. Supraanal seta 225 µm long.

Remarks: Larvae were collected from the sublittoral zone of a reservoir. They are small with a relatively short basal antennal segment and low antennal ratio and rather shallow lateral notch on the trifid median mental tooth. The mandible resembles somewhat that of Cryptotendipes pseudotener , with two flat inner teeth and a long seta subdentalis that almost reaches the apex of the apical tooth. Of all the described freshwater larvae in this genus, only C. usmaensis , C. emorsus , and C. pseudotender have flat mandibular inner teeth. Cryptotendipes usmaensis and C. emorsus can be separated from our material by the short seta subdentalis reaching no farther than to the second inner tooth, whereas in our material, the seta subdentalis clearly extends to the base of the apical tooth. Cryptotendipes pseudotener can be separated from the larvae of other species, which have a single, broad median mental tooth; our specimens clearly have trifid median teeth. The larva can not be associated with any of the adults described in this paper. We, therefore, treat this larva as C. sp. 1.

Figures

FIGURE 5. Cryptotendipes sp. 1. Fourth­instar larva. A. Gula and posterior occipital margin. B. Antenna. C. Labrum. D. Mandible. E. Maxilla. F. Mentum.