Acanthagrion gracile (Rambur)

Anjos-Santos, Danielle, Carriço, César, Costa, Janira Martins & Santos, Tatiana Chrysostomo, 2011, Description of the final instar larvae of Acanthagrion gracile (Rambur) and Acanthagrion lancea Selys (Odonata: Coenagrionidae), Zootaxa 2832, pp. 44-50 : 45

Acanthagrion gracile (Rambur)

Description of last instar larva ( Figs. 1–7 ). Head. Almost two times as wide as long, posterolateral margins slightly concave, posterior angle with several short spines ( Fig. 1 ). Posterior margin concave. Five or six spines on inferior border of eyes near maxillae. Antennae 7-segmented, the third antennomere the longest. Labium reaching second coxae; prementum subtriangular, almost 1.3 times as long as wide; anterior margin convex and slightly crenulated, with 6 or 7 premental setae (3 or 3+1), the inner one shorter than the others; lateral margin with about 9 spiniform setae ( Fig. 2 ). Labial palp with four setae; outer half of distal margin with three or four very small teeth, inner half with three teeth and a curved end hook; movable hook slender and sharp; inner margin of palp slightly crenulated ( Fig. 3 ). Mandibular formula: L 1+2 3 4 5 0 a b, R 1+2 3 4 5 y a ( Figs. 4 a,b).

Thorax. Wing pads nearly parallel, the external ones reaching middle of S4. Legs pale; femora with a row of spiniform setae on the dorsal and lateral surface; tibiae with sparse, long and delicate setae on the external surfaces; tibiae I with delicate setae on the internal surface, tibiae II and III with a row of spiniform setae on the anterior half of the middle internal surface, apical ends of tibiae with a delicate group of setae on the internal surface; tarsi with two rows of setae on the ventral surface.

Abdomen. Cylindrical. Light brown. Dorsal spines on the tergite surface S7–10, thicker on S9–10. A row of lateral spines on S2–10, thicker on S5 –10. Male gonapophyses sharply pointed and divergent, reaching base of S10 ( Fig. 5 ). Female gonapophyses exceeding posterior margin of sternite 10, lateral valvae sharply pointed with a ventral row of 7 robust spiniform setae increasing in size posteriorly ( Fig. 6 ). Male cerci as in Figure 5 and female cerci as in Figure 6 . Caudal lamellae lanceolate, with width/length ratio 0.12 ( Fig. 7 ). Dorsal margin of lateral caudal lamella with about 50 setae; ventral margin with about 20 setae. Tracheation as in Figure 7 .

Measurements (mm): Total length (without caudal lamella) (N=8): 11.45 [10.47–12.82]. Head: maximum length: 1.43 [1.28–1.56]; maximum width: 2.77 [2.65–2.86]. Prementum: maximum length: 1.97 [1.77–2.23]; maximum width: 1.48 [1.38–1.56]. Thorax: femur I: 1.42 [1.29–1.66]; femur II: 1.88 [1.64–2.07]; femur III: 2.43 [2.24–2.66]; tibia I: 1.70 [1.39–1.89]; tibia II: 2.09 [2.00–2.30]; inner wing pads maximum length: 3.78 [3.65– 3.87]; outer wing pads maximum length: 3.52 [3.32–3.58]. Abdomen: total length: 7.49 [6.83–8.95]; S9 length: 0.53 [0.36–0.69]; S10 length: 0.44 [0.30–0.54]; cerci length: male (N=3): 0.23 [0.22–0.25], female (N=6): 0.14 [0.10–0.19]; female gonapophyses length (N=6): 0.95 [0.90–0.99]; male gonapophyses length (N=3): 0.36 [0.35– 0.37]. Lateral caudal lamella (N=8): maximum length: 6.34 [6.13–7.11].

Specimens examined: 8 exuviae (3 males and 5 females reared). BRAZIL: Espírito Santo State, Estação Biológica de Santa Lúcia, Lagoa Molino, 24.vii.2009, leg. D. Anjos-Santos, C. Carriço, J. M. Costa & T. C. Santos (2 3) [emerged in laboratory: 29.vii. 2009; 02.viii.2009]. Rio de Janeiro State: Nova Iguaçu, Tinguá, Reserva Florestal, 09.iv.1971, leg. N. D. Santos (1 3) [emerged in laboratory, date not determined]; Areal, Fazenda São Joaquim, 10.vii.1969, leg. N. D. Santos & J. P. Machado (2 Ƥ) [emerged in laboratory, date not determined]; Rio de Janeiro: Quinta da Boa Vista, Horto do Museu Nacional, 04.ix.1980, leg. N. D. Santos & H. Mesquita (1 Ƥ) [emerged in laboratory, date not determined]; Tijuca, Açude da Solidão, 02.viii.1967, N. D. Santos (1 Ƥ) [emerged in laboratory, date not determined]; Silva Jardim, Juturnaíba, Rio São João (CEDAE), 17.ix. 1978, leg. N. D. Santos (1 Ƥ) [emerged in laboratory, date not determined].

Figures

FIGURE 1 – 7. Acanthagrion gracile, details of larval morphology: (1) head, dorsal view; (2) prementum, dorsal view; (3) labial palp, dorsal view; (4) mandible, inner view: (a) right mandible, (b) left mandible; (5) male gonapophyses and cerci, lateral view; (6) female gonapophyses and cerci, lateral view; (7) lateral caudal lamellae, lateral view.