Fig. 4 (app), Fig. 7 (penis), Fig. 11 (prothorax), Fig. 15 (habitus and head).
Holotype. ♂ (FAAL NC 4309), Brazil: Bahia: Jussari; Projeto Leptagrion —RPPN Serra do Teimoso, 12.IV.2009, K.S. Furieri leg.
Etymology. I named this species vilelai (a noun in the genitive case) in honor of Dr. Diogo Silva Vilela, longtime friend, diligent and tireless worker and fellow odonatologist.
Description of holotype
Head. Labrum, anteclypeus, genae and outer surface of mandible, postclypeus and postfrons up to vertex yellow, epicranium black, antennae: missing (Fig. 16B). Labium and maxillae pale yellow. Rear of head pale, black around the occipital foramen (Fig. 16C).
Thorax. Prothorax dorsally black, ventrally brown; pterothorax: Mesepisternum and mesepimeron black, humeral stripe, metepisternum, metepimeron, metinfraepisternum brown. Legs: coxae brown, femora, tarsi and tarsal claws black. Wings hyaline with black venation, pterostigma reddish, quadrangular and surmounting little more than the cell beneath it.
Abdomen. Anterior half of S1, dorsum of S2–6 black, S1–6 ventrally brown, S7–10 black. Penis as in Fig. 8. Appendages black.
Measurements (in mm). Total length (incl. apps) 40.6: abdomen (incl. apps) 33, hindwing 21, Forewing 20.5.
Diagnosis. (contrasting character in parentheses). Leptagrion vilelai has the anterior part of head ranging from yellow to orange as in L. auriceps but the occiput black (while in L. auriceps it is orange), these characteristics also differentiate it from L. bocainense and L. macrurum. Lateral border of the posterior lobe of prothorax in lateral view in the shape of “~” (in L. auriceps is roughly straight (Fig. 8), in L. macrurum is roughly in the shape of “U” (Fig. 10) and in L. bocainense as in figure 9), pterostigma quadrangular as in L. bocainense (lozenge-shaped in L. macrurum and L. auriceps). Medio–longitudinal laminar process of penis S3 longer than S3 (shorter than S 3 in L. macrurum).