Matrona basilaris Selys, 1853

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 : 584-590

Matrona basilaris Selys, 1853

Specimens studied. Larvae: 1 ♂ ( AHLA05 ), 1 ♀ ( AHLA14 ), China, Anhui, Liuan, Jinzhai (115.9585° E, 31.5519° N), 1-v-2015, Hongqu Tang leg. ; 2 ♀ # ( AHLA09 , AHLA13 ), China, Anhui, Liuan, Jinzhai, Tiantangzhai (115.7875° E, 31.1362° N), 2-v-2015, Xin Yu leg.

Description. Diagnosis. A slender zygopteran with a depressed and small head, long legs with distinct bands, long abdomen with long sword-like gills. Ground colour of body dark brown ( Fig. 2 b) but much varied between individuals.

Head. Flattened above, widest across the eyes; in dorsal view general shape a compressed pentagon. Postocular lobes little developed so hind margin of head very narrow at base; indistinct (in dorsal view) prouberances about halfway between eye and posterior angle. Antennae 7-segmented, long and robust, with strong and long segment 1 which is almost as twice as remaining segments combined, and short segment 2–7 tapering from proximal to distal ( Figs. 3 b, d). Prementum elongate, strongly dilated distally, about 2 times as long as broad; anterior margin strongly cleft and forming a pair of knife-like prominences, each prominence bearing three pairs of setae, the most basal pair as long as the middle pair ( Fig. 4 c). Labial palp robust with three strong, long, and incurved distal teeth, of which the middle one is the longest; movable hook very long and robust with two setae on its base ( Fig. 4 c). 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, almost reaching to the end of the most distal spines on galeo-lacinia, covered in dense long hairs ( Figs. 5 e–h). Right mandible ( Figs. 6 e–f) with four rather long and well developed incisors and a fifth innermost tooth; molar crest is greatly reduced (R 1’1234 y ab, 1’ <1 <2 <4 <3, a <b). Left mandible ( Figs. 6 g–h) with four shorter incisors; molar crest produced straight, distal edge serrated with 11 fine cusps (L 1’1234 0 a (m1-9) b, 1’ <1 <2 <4 <3, a <b).

Thorax. Prothorax weak, narrow than both 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 distinct dark bands. Wing pads not divergent, narrow, moderate long, just exceed middle of S3 ( Fig. 2 b).

Abdomen. Slender, elongate. Gonapophyses very small in male, projecting from middle of S9 to the two-thirds of this segment ( Fig. 7 c). In female outer gonapophyses projecting from anterior margin of S9 almost to the end of S10; inner gonapophyses as long as the outer ( Fig. 7 d). Cerci wholly concealed by caudal gill in ventral view ( Figs. 7 c–d). Paired, long triquetral lateral gills and single lamellate median gill both bearing with setae-like spines along margins and blunt apexes ( Figs. 8 c–d). Lateral gills longer than the middle and both marked with dark spots ( Figs. 9 c–d).

Microhabitat and behaviour. Larvae were found both in small montane streams with sandy substrates and open rivers with stony substrates ( Figs. 11–12 ). Some even occurred in very small puddles covered with dense vegetation formed by discontinuous streams. They were usually concealed among stones and gravel, or in water plants, depending on their body colour. The habitat usually had many adults of Mnais tenuis Oguma, 1913 .

Diagnosis. Generally, the larvae of Vestalaria and Matrona have similar appearance, such as a slender body, small head, long and banded legs, and elongate sword-like caudal gills. However, they can be separated easily by several characters listed below ( Table 2).

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 11. Habitat of the larva of Matrona basilaris in Liuan, Anhui. Small montane streams with sandy substrates.

FIGURE 12. Habitat of the larva of Matrona basilaris in Liuan, Anhui. Open rivers with stony substrates.