Leptagrion dispar Selys, 1876

Santos, Laís Rodrigues, Ribeiro, Cintia, Mariano, Rodolfo & Rodrigues, Marciel Elio, 2020, Description of the larva of Leptagrion dispar Selys, 1876 (Odonata: Coenagrionidae) with notes on distribution and ecology of the specie, Zootaxa 4896 (1), pp. 131-139 : 134-136

Leptagrion dispar Selys, 1876

Description of last instar larva

Figs. (3a–j)

General. Overall color pale yellow, except for the caudal lamellae, which are dark brown. Total length (n=11), without lamellae 18.45mm (16–23) ( Fig. 3A ).

Head. 1.5x wider than long. Frontoclypeal area and labrum pale yellow, labrum rounded. Antennae 7–segmented, the third antennomere is the longest and the seventh antennomere is the shortest, size proportions of antennomeres: 0.40, 0.53, 1.0, 0.88, 0.63, 0.37, 0.12 ( Fig. 3B ). Labium reaching first coxa, prementum almost as long as wide, with four long setae on each side; anterior margin smooth and rounded; lateral margins with 14 setae at widest portion. Labial palp with 11 long setae each side, distal margin bilobate, both lobes acute and straight, the mobile hook is the longest ( Figs. 3 c–d). Right mandible ( Fig. 3e ) without molars, with five incisors and two additional teeth, a large one on posterior margin (y) and a small one on anterior margin below level of left molars (k). Left mandible ( Fig. 3f ) with two molars, five incisors, and two additional teeth; one next to incisor 5 (y) and the other tooth on anterior margin below molars (k). Mandibular formula: R 11’234 yk / L 11’234 yk ab.

Thorax. Prothorax dorsally brown with dark brown margins. Meso– and metathorax blackish with pale areas on metathoracic margins. Legs pale with following dark pattern on the apical band on all tibiae. Wing pads parallel almost reaching S4.

Abdomen. Dorsally light brown; S1–10 with lateral and apical margins smooth, without thorns or bristles; S8–10 with darker apical region. Male gonapophyses acute, reaching 0.5 of S10 length ( Fig. 3g ). Valves of ovipositor pale brown, not denticulated, reaching 0.5 of S10. Male cercus blunt, blackish and short, with less than 0.5 of S10 ( Fig. 3G ). Dorsal margin of lateral caudal lamella with 18–20 stiff setae, dorsal margin of medial caudal lamella smooth, without stiff setae; caudal lamellae with a petiole at the base that extends from the distal half, irregular margins in the apical region; dark color that tends to be lighter at the margins; apical region of the lamellae lighter in color ( Figs. 3 h–j).

Measurements. Head: width 6.1mm (5.9–6.3) and length 3.7mm (3.3–3.7). Antennae total length: 3.8mm (3.4–4.0). Labium: width 4.1mm (4.0–4.5), length 4.5mm (3.9–4.7). Leg length: I 11.2mm (5.5–15.5); II 13.2mm (6.4–18.9) and III 15.2mm (7.5–21.2). Abdomen length: 11.2 mm (7.2–15.5). Caudal lamella: lateral length 7.7mm (6.1–8.2), medial length: 5.1 (3.6–6.5).

Variation between specimens. Setae papal: six specimens had 11, three specimens had 12 and two specimens had 10 long setae each side;

Diagnosis. Leptagrion dispar differed from all other larvae described with the exception of L. perlongum by the number of premetal setae 4/4. However, in L. dispar all premental setae are long (primary) and the mandibles have two molars (L11’234 yk ab/R11’234 yk), whereas L. perlongum has one premental setae long (primary) and three shorts (secondary) and the mandibles only have one molar (L11’234 y ab/R11’234 y) ( Table 1 ).

Habitat and Ecology. The larvae of L. dispar were collected in bromeliads in the soil in open areas and in bromeliads developed under the mangrove plants. The larvae were almost always found in the lateral tanks of the bromeliads, which is usually the oldest region of the plant. When the larvae found were close to the last instars, the bromeliad usually had only one individual. The adult males, when present, were always perched on the bromeliads and never close to another male, thus emphasizing their possible territorial behavior in relation to breeding habitats. However, conflict between males was not observed.

Figures

FIGURE 3. Leptagrion dispar. a—Last larval instar, dorsal view; b—Head and thorax—dorsal view; c—Prementum—dorsal view; d—Labial palp, dorsal view; e—Right mandible, inner view; f—Left mandible, inner view; g—Gonapophysis and cercus of the male, ventral view; h—lamellas—dorsal view; i—Median caudal lamella—dorsal view; j—Lateral caudal lamella, lateral view. Scales: Fig. a = 5 mm, Figs. b–d = 1 mm, Figs. e–f = 0,5 mm, Figs. g–j = 1 mm.