Vestalaria venusta Hämäläinen, 2004

Wang, Runxi, Yu, Xin, Xue, Junli & Ning, Xin, 2017, Descriptions of larvae of Vestalaria venusta (Hämäläinen, 2004) and Matrona basilaris Selys, 1853 (Odonata: Calopterygidae), Zootaxa 4306 (4), pp. 580-592 : 583-584

Vestalaria venusta Hämäläinen, 2004

Material studied. Adult 1 ♂ ( SCYA08 ) and larvae 1 ♂ ( SCYA05 ), 1 ♀ ( SCYA06 ): China, Sichuan, Yaan, Bifengxia Town, Houyan Village (103.0472° E, 30.1019° N), 25-vii-2011, Xin Yu leg.

Description of larva.

Diagnosis. A slender zygopteran with a relatively small head, long legs with distinct bands, and long abdomen with long sword-like gills. Ground colour of body pale brown ( Fig. 2 a).

Head. Relatively small; in dorsal view general shape a compressed pentagon. Postocular lobes somewhat swollen, terminating in a pair of small dorsal upward-directed protuberances. Antennae 7-segmented, long and robust, especially segment 1 which is very strong and almost twice as long as all other segments together. Segment 2–7 gradually short and tapered from base to apex ( Figs. 3 a, c). Prementum elongate, strongly expanded distally, about 1.5 times as long as broad, anterior margin deeply cleft with a pair of knife-like projections obliquely truncated apically, each bearing three pairs of setae, the most basal pair only one third as long as the middle pair which is not obvious ( Figs. 4 a–b). Labial palp robust with three strong, long and incurved distal teeth, of which the middle one is the longest; inner margin of the palp slightly produced, bearing two pairs of setae; movable hook very long and robust ( Figs. 4 a–b). Maxilla 1.5 times as long as broad; galea and lacinia partly fused; lacinia terminating in four long sharp spines, forming a curved, inward-directed, pitchfork-like structure; galea with three shorter spines directed upward. Palp with short basal segment and a single long banana-shaped terminal segment, reaching to half of most distal spines on galeo-lacinia, covered in dense long hairs ( Figs. 5 a–d). Right mandible ( Figs. 6 a–b) with four long and well developed incisors and a fifth innermost tooth; third incisor is the longest; molar crest produced to form two well-defined curved bifid spine (R 1’1234 y ab, 1’ <1 <2 <4 <3, a <b). Left mandible ( Figs. 6 c–d) with four shorter incisors; molar crest produced straight, distal edge serrated with even dense tiny teeth between a and b (L 1’1234 0 a (m 1-11) b, 1’ <1 <2 <4 <3, a <b) of which it was difficult to determine the exact number.

Thorax. Prothorax not strong, narrower than both head and meso- and metathorax; meso- and metathorax almost rectangular in shape. Legs long and progressively slightly longer from pro- to metathorax. Femur slightly longer than tibia, each with two well defined dark bands. Wing pads narrow and not divergent, moderate long, just exceeding proximal edge of S4 ( Fig. 2 a).

Abdomen. Slender, elongate. Gonapophyses small in male, projecting from middle of S9 to the two-thirds of this segment ( Fig. 7 a). In female outer gonapophyses projecting from middle of S9 to end of S10; inner gonapophyses reaching still a little further ( Fig.7 b). Cerci wholly concealed by caudal gills in ventral view ( Figs. 7 a–b). Paired, long triquetral lateral gills and single lamellate middle gill both bearing tiny setae-like spines along margins ( Figs. 8 a–b). Lateral gills with sharp apex always longer than the middle which has a nearly rounded apex, and both marked with dark spots ( Figs. 9 a–b).

Microhabitat and behaviour. Larvae were found in a small montane stream with shallow water and stony substrates ( Fig. 10 ). Meanwhile, adults of M. oreades , Anisopleura qingyuanensis Zhou, 1982 , Archineura incarnata and Sympetrum eroticum (Selys, 1883) were present around the site in moderate numbers. The larvae were usually found concealed under stones or gravel in the day time and active at night.

Figures

FIGURE 2. Larval habitus of: (a) Uestalaria venusta and (b) Matrona basilaris.

FIGURE 3. Lateral and dorsal view of top of the head: (a, c) Uestalaria venusta; (b, d) Matrona basilaris. Protuberances on postocular lobes are been indicated with red arrows.

FIGURE 4. Dorsal view of prementum and labial palps: (a) Uestalaria venusta, right prominence broken; (b) U. venusta, outer distal teeth of left labial palp broken; (c) Matrona basilaris. Positions of lost setae were indicated with little arrows, black ones for long setae and red for short.

FIGURE 5. Maxilla of Uestalaria venusta: (a) left, posterior surface; (b) right, posterior surface; (c) left, innter surface; (d) right, innter surface. Maxilla of Matrona basilaris: (e) left, posterior surface; (f) right, posterior surface; (g) left, innter surface; (h) right, innter surface.

FIGURE 6. Mandible of Uestalaria venusta: (a) right, posterior surface; (b) same, innter surface; (c) left, posterior surface; (d) same, innter surface. Mandible of Matrona basilaris: (a) right, posterior surface; (b) same, innter surface; (c) left, posterior surface; (d) same, innter surface.

FIGURE 7. Gonapophyses in ventral view: (a) Uestalaria venusta male with caudal gills removed to show cerci; (b) U. venusa female; (c) Matrona basilaris male with lateral caudal gills removed to show cerci; (d) same female with caudal gills removed to show cerci.

FIGURE 8. Distal part of caudal gills in lateral view: (a) lateral gill of Uestalaria venusta; (b) middle gill the same; (c) lateral gill of Matrona basilaris; (d) middle gill the same.

FIGURE 9. Caudal gills in lateral view: (a) Uestalaria venusta middle; (b) same lateral; (c) Matrona basilaris middle; (d) same lateral.

FIGURE 10. Habitat of the larva of Uestalaria venusta in Ya’an, Sichuan.