Paraleuctra tianmushana

Li, Weihai, Li, Kefan, Wang, Rongfeng & Yang, Ding, 2016, The first description of the larvae of the Chinese species Paraleuctra tianmushana Li & Yang (Plecoptera: Leuctridae), Zootaxa 4061 (1), pp. 93-100 : 97-100

Paraleuctra tianmushana Li & Yang, 2010

( Figs. 1–6)

Paraleuctra tianmushana Li & Yang. 2010. In Li, Wang & Yang, 2010. Zootaxa 2350:47; Du & Qian. 2012. Journal of Natural History 46 (17–18):1062.

Larval morphology. Body length, male 6.1–6.2 mm, female 7.9–8.1 mm. General body colour yellowish-brown with distinctly darker pattern. Antennae with at least 35 segments, each segment with very short apical hairs. Head with several bristles behind the compound eyes ( Figs. 1–2). Lacinia ( Fig. 4 ) narrow and triangular and palmate, with two large apical and two shorter subapical stout teeth, and followed by dorsal and ventral rows of sharp medium-sized spines ( Fig. 4 d); right mandible with four stocky triangular apical cusps and molar cup with about 18–20 curved, comb-like inner teeth before blade-like scraping ridge ( Figs. 4 a–c). The neck bears vestigial cervical gills on the outer side of each cervical sclerite of prosternum ( Fig. 6 a). Pronotum with each corner bearing 1–4 bristles on each corner and with distinct median pattern. Mesosternal Y-ridge with prominent median ridge between the anterior arms and unpigmented hardly visible posterior double Y-stem with extended arms connecting the inner-posterior corners of furcal pits ( Fig. 6 b). Wing pads glabrous, four or more times longer than wide and generally situated parallel to body axis. Femora and tibia of foreleg with scattered, sparse silky hairs; tibia apex with several (ca. 10) tiny spines and two large spines, tarsal segments 1–2 with three irregular ventral rows of short hairs, the 3rd segment with single row of short tiny spines ( Figs. 5 a–d). Hind leg with fewer hairs but tibiae with two or three sharp spines, tarsal 3rd segment almost without ventral spines but two ventral spines at base ( Fig. 5 e). An irregular row of chloride cells are present along femur and two rows of chloride cells on tibiae of hind leg ( Figs. 5 e–f). Abdominal terga glabrous without posterior, lateral, or surface setae, distinct pigment patterns of the male and female similar to adult stage as figured in Li et al. (2010). Pleural fold present on sternal segments 1–6. Developing male genitalia visible dorsally and ventrally through larval exuvium ( Figs. 6 c–e). Cerci with at least eight segments (incomplete), those below segment two with 3–4 apical setae, some approximately half as long as the bearing segment and one somewhat perpendicular setae longer than the bearing segment, and between setae there have small spines ( Figs. 3 a–e); the base of segment 7–8 have abundant pits ( Fig. 3 f).

Material examined. China, Shaanxi Province, Foping County, Sanguanmiao Management Station, 2011. IV. 18, Weihai Li: 2 pharate male larvae and 3 pharate female larvae (deposited at HIST), 1 pharate male larvae and 1 pharate female larvae (deposited at HNHM).

Distribution. The species was previous recorded from Henan and Zhejiang provinces of China. The above records are the first report for Shaanxi Province.

Remarks. Generally, the larvae of this species agree with the five generic characters by Stewart & Stark (2002), i.e. (1) unclothed paraprocts, (2) tufts of setae only on corners of pronotum (3) Ab1-6 divided by ventrolateral membrane, (4) pronotal setae present only on corners, (5) double mesosternal Y-ridge stem and median longitudinal extension between the arms, although with some variations in shape. The scraping ridge of both mandibles ( Figs. 4 b, 6f) in P. tianmushana is blade- like and not pectinate, typical of the genus. However, the usual hair brushes between dorsal and ventral teeth in larvae of Leuctrinae is absent in P. tianmushana (figs. 8.1– 8.18 in Stewart and Stark 2002). A very peculiar feature is the presence of vestigial cervical gills, which were unknown among Leuctridae . The larva of P. tianmushana can be distinguished from the four known Nearctic Paraleuctra larvae on the basis of lack of abdominal setation; this feature cannot be judged on the basis of available figures on the further Palearctic species. Paraleuctra tianmushana is a member of the sara species group. Stark (2002) (in Stewart and Stark 2002) distinguished the known larvae of this group from those of the occidentalis species group by their reduced body setation.

Figures

FIGURE 3. Pharate nymph of Paraleuctra tianmushana Li & Yang. a. pharate male nymph, terminal segments, dorsal; b. pharate female nymph, cercal segments 1 – 4, ventral; c. pharate male nymph, cercal segments 1 – 5, dorsal; d. pharate male nymph, cercal segments 6 – 8, dorsal; e. pharate male nymph, cercal segments 8, dorsal; f. surface details of cercal segments 8, dorsal.

FIGURE 4. Pharate nymph of Paraleuctra tianmushana Li & Yang. a. Right mandible, ventral. b. Right mandible, pectinate comb of molar cup. c. detail of pectinate comb. d. Apex of left lacinia, ventral.

FIGURE 5. Pharate nymph of Paraleuctra tianmushana Li & Yang. a. Right foreleg femur and tibia, anterior. b. Foreleg tarsus, ventral. c. Tarsal segments 1 – 2 of foreleg. d. Right hind leg femur and tibia. e. Right hind leg tarsus. f. Chloride cells on femur of right hind leg.

FIGURE 6. Pharate nymph of Paraleuctra tianmushana Li & Yang. a. Prosternum. b. Mesosternum. c. Adult male terminalia exposed by clearing, dorsal view. d. Male terminalia exposed by clearing, ventral view. e. Adult female terminalia exposed by clearing, ventral view. f. Left mandible, ventral. epi, epiproct; sr, scraping ridge.