Aethriamanta brevipennis (Rambur, 1842) Kalkman et al., 2020

Description of the exuvia of Aethriamanta brevipennis View in CoL

Material. Two male larvae collected from Thumboor wetlands, Thrissur district, Kerala, INDIA; 10.2976° N, 76.2565° E, 25 m a.s.l, 19.xi.2023, A. Vivek Chandran leg. ( Fig. 3 View FIGURE 3 ). Larvae emerged into adult on 14.xii.2023 and 15.xii.2023; specimens to be deposited at Research Collection Facility, NCBS, Bengaluru GoogleMaps .

Description. Exuvia light to dark brown in colour, head and wing sheaths darkest.

Head: Light brown with lighter portions marked with prominent dark minute spots. Occiput with numerous long hairs. Compound eyes more than half length of the head and bulging laterally ( Fig. 2A View FIGURE 2 ). Antennae 7-segmented, third segment longest. Labrum light brown with fine long setae anteriorly. Clypeus light brown in the middle, darker at the sides and without prominent setae. Frons and vertex marked with numerous dark brown spots and edges with numerous hair-like setae. Five balloon shaped light brown areas extend from occiput towards vertex; occiput with numerous dark brown, short, stout setae along with few long hair-like setae except on those balloon shaped areas. Mandibles have the formula L 1234 0 ab’b/R 1234 y abcd, with a <b in the left mandible ( Fig. 2D View FIGURE 2 ), and tooth d being the largest in the right mandible ( Fig. 2E View FIGURE 2 ). The galeolacinia of the maxilla features six teeth ( Fig. 2C View FIGURE 2 ). The two dorsal teeth are slightly curved inward, with similar lengths and robustness, while the basal-most dorsal tooth is more slender and shorter. The three ventral teeth vary in size and robustness: the basal tooth is very small, and the apical tooth is the largest. Labium spoon-shaped ( Fig. 2B View FIGURE 2 ), short (length:width ratio=1.2:1), with a smooth lateral margin, light brown colour, densely spotted with darker brown, the prementum-postmentum articulation reaches until the middle of the mesosternum. Distal margin of palp with crenations indistinct, with prominent spines arranged in a group of three, among which two are longer and of same length. Inner margin has spines equally spaced. Anterior margin of prementum angular in shape, forwardly projected and with minute spines of equal length at equal intervals. Premental setae 12–12 (6 longer and 6 shorter) and palpal setae 7–7, movable hook of the labial palp not very strong and without any secondary spines on it.

Thorax. Prothorax narrower than head, pronotal disc semicircular bearing laterally placed long hair-like setae ( Fig. 2H View FIGURE 2 ). Tergal folds at the base of the wing sheaths with 3–4 long setae closely arranged in a row and few minute setae scattered around the row. Prominent mesostigma with higher chitin deposition. Sternum with more setae than tergum, anterior margin of mesosternum with a dense row of setae, metasternum with fewer setae. Wing sheaths of equal length, hind wing sheaths reaching the basal half of S6, with numerous setae on dorsal margin, a few are quite long hair-like setae, the remaining are spiniform setae. Legs light brown with very faint banding patterns; coxa with numerous rows of setae on ventral side; femur with a row of setae on both dorsal and ventral side, those on ventral side longer; tibiae are the most setose part of the legs with parallel rows of long hair-like setae on distal margin. Tarsi with rows of small spines ventrally. Tibial comb with monodentate setae.

Abdomen. Dark brown, short, marked with lighter patches, prominent circular patches along the lateral margin of S4–7. Dorsal spines present on S5–8, those on S7–8 the most prominent ( Fig. 2F View FIGURE 2 ), shorter than the dorsal length of their respective segments. S2–4 with two long, dark brown to black, hair-like setae on the middorsal line at distal margin of each segment. S7–9 with numerous long setae and few minute spines serially arranged along the distal margin which gives the abdomen a hairy appearance ( Fig. 2I View FIGURE 2 ). Lateral spines on S8–9 short, slightly curved inward. Anal pyramid short, not protruded beyond the lateral spines on S 9 in live condition, whereas to some extent protruded beyond the lateral spines of S 9 in the exuviae. Epiproct triangular in dorsal view, wider than long; paraprocts slightly longer than the epiproct. Cerci more than 3/4 length of epiproct ( Fig. 2J View FIGURE 2 ). All anal appendages with numerous, very minute spines on distal margins.

Measurements (male exuvia) (in mm): Total body length 13, Maximum head width 4.2, abdomen length 6.8, maximum abdomen width 4.8; hind wing sheath length 4.1, hind femur length 4.14.

Diagnosis: The larva of A. brevipennis is easily diagnosed by the presence of dorsal abdominal spines on S5–8 ( A. nymphaeae and A. circumsignata larvae lack dorsal abdominal spines and A. rezia larva has dorsal abdominal spines present on S2–8) and prominent long hairs almost all over the body. Presence of dorsal abdominal spines is thought to be crucial for larval identification ( Suhling et al. 2014), though this genus exhibits both presence and absence of dorsal spines.

Habitat: The larvae were collected from an open pond overgrown with Salvinnia molesta, near a paddy-field ( Fig. 4A View FIGURE 4 ) where several adult dragonflies were seen ( Fig. 4B View FIGURE 4 ). The water quality parameters measured were as follows: temperature = 36.1°C, pH = 7.17, dissolved oxygen = 7 mg /L, conductivity = 0.17 µS/cm, turbidity = 14 NTU, total dissolved solids = 0.12 ppm, salinity = 3 ppt and depth = 51.5 cm. Active foraging by larvae was observed mostly at night in the aquarium. They preferred to rest hidden among the plants during daytime.