Heteragrion lencionii, Vilela, Farias & Santos, 2021

Description of the female of Heteragrion lencionii

( Figures. 2a–g View FIGURE 2 ; 3a–c View FIGURE 3 ; 4a View FIGURE 4 )

Material examined: ♀ (B0764 described here) (mating with B0765), Brazil, Sergipe, São Cristóvão , Federal Institute of Sergipe (-10.9198, -37.1862, 30 m asl), 29.xi.2023, A.B.S. Farias leg. (UFS) GoogleMaps ; 2♀♀ (B0766; B0767), the same data, but 30.iii.2023 and 13.iv.2023, respectively; A.B.S. Farias leg. ( UFS) GoogleMaps .

Head ( Figs. 2a–d View FIGURE 2 ; 3a View FIGURE 3 ; 4a View FIGURE 4 ). Labium yellow pale colored; labrum orange-brown with a medial dark stripe; base of mandibles and genae pale colored, apex of mandibles reddish black; anteclypeus and postclypeus light orange-brown with a large medial stripe; antefrons orange-brown with a slender dark stripe; postfrons orange, with two lateral black stripes from the base of the antennae to the eyes; dark spot between the anterior and lateral ocelli; black stripe on occipital bar; remainder of the head orange.

Thorax ( Figs. 2a, d View FIGURE 2 ; 3b View FIGURE 3 ; 4a View FIGURE 4 ). Prothorax: Anterior lobe pale, with black margins; medial lobe pale with slightly darker spots on the sides and a small dark spot; distal margins of posterior lobe rounded and pale, and proximal margin slightly pointed with a wide central black spot connecting to the spot on the medial lobe; intersternite clubshaped with convex margin of the carina, as long as the setifer, dorsal plate rounded, and posterior plate absent. Pterothorax: Middorsal carina black; mesepisternum light brown with a dark spot above the mesopleural fossa; mesinfraepisternum pale with a light brown spot; mesepimeron, metepisternum, and metepimeron mostly light brown.

Wings ( Figs. 2a View FIGURE 2 ; 3c View FIGURE 3 ). Hyaline with dark brown venation; pterostigma brown, pale centrally and overlapping with two cells in all wings; 14 Px in LFW and 13 in LHW, 16 Px in RFW, and 15 in RHW.

Abdomen ( Figs. 2a View FIGURE 2 ; 4a View FIGURE 4 ). S1 with a brown dorsal spot and pale lateroventrally; S2 black dorsally and pale lateroventrally; S3–6 dark brown with pale basal rings and small black squared apical spots; S7 dark brown with a slightly lighter basal ring; S8 with a thin pale basal ring, with small subapical denticles; S9 dark brown with a pale transverse wave; S10 dark brown dorsally and pale laterally, with prominent denticles.

Anal appendages ( Figs. 2a, e–g View FIGURE 2 ; 4a View FIGURE 4 ). Genital valves do not extend beyond S10; pale coloration, dark brown denticles, and stylus; at least three rows of denticles on ventral edge of genital valves, gradually increasing in size towards the apex, reaching up to four times the size of the proximal denticles; cerci brown at base and black apically.

At least three rows of denticles on the ventral margin of the genital valves gradually increase in size towards the apex, reaching up to four times the size of the proximal denticles.

Measurements. FW: 24.57; HW: 23.85; AL: 31.75; TL: 39.69.

Variations in specimens. Females did not vary in anal appendage morphology. The morphology of the intersternite differed between specimens; individual B0766 had a margin of the carina slightly straighter and a darker-colored dorsal plate, whereas individual B0767 had a margin of the carina straight and a paler dorsal plate, similar to B0764. Slight differences were observed in the coloration of the pterothorax and abdomen, probably related to intraspecific differences, age, and postmortem conditions. The second female had 18 Px in LFW and 15 in LHW, 18 Px in RFW, and 15 in RHW; the third female had 16 Px in LFW and 15 in LHW, 17 Px in RFW, and 15 in RHW. Female specimens varied in size as follows: FW: 22.78–24.21, HW: 22.20–23.68, AL: 28.2–30.84, TL: 35.45–38.68.

Differential diagnosis. Among the species of Group A, H. lencionii is morphologically closer to H. aurantiacum Selys, 1862 , H. cinnamomeum Selys, 1862 , and H. silvarum Sjöstedt, 1918 , being the males separated by the morphology of the cerci ( Vilela et al. 2021). Unfortunately, H. cinnamomeum females have not yet been described. Heteragrion lencionii female differs from its described congeners primarily in head coloration and black markings, the shape of the hind lobe of the prothorax, which has a convex margin with a slight acute medial projection, the club-shape of the intersternite, the absence of black humeral spots, and the coloration of the pterostigma with a paler central region ( Figs. 2d View FIGURE 2 ; 3a–c View FIGURE 3 ). In females of H. aurantiacum collected in the Serra of Itabaiana National Park, the markings on the head, prothorax, and pterothorax had different arrangements; the posterior lobe of the prothorax had straighter and sharper margins, the intersternite had a straighter carina margin than in H. lencionii , and the dorsal plate was cone-shaped, whereas in H. lencionii it was rounded ( Fig. 3d–f View FIGURE 3 ).

Ecological notes. The female was found on branches along the banks of the stream originating from the Poxim River, just below a bridge marking the border between the Federal Institute of Sergipe and the Federal University of Sergipe (Rural Campus) ( Fig. 4c–d View FIGURE 4 ). The stream is approximately 3 m wide, with riparian vegetation and shaded and sunny stretches. Dams are frequently visited by the local population upstream for recreational purposes. In addition, the area is surrounded by buildings, pastures, and experimental agriculture ( Vilela et al. 2021). Although we believe that the surrounding fragments are minimally preserved, these conditions may affect local biodiversity. It is important to emphasize that since the collection and description of the H. lencionii male ( Fig. 4b View FIGURE 4 ) in the Serra of the Itabaiana National Park, the species has not been collected or even sighted at that location. Fortunately, we identified a stable population at this locality.

Final remarks. To date, information on 19 females from group A of the genus Heteragrion is available (Ávila et al. 2017, 2020; Cezário & Guillermo-Ferreira 2021; Daigle & Tennessen 2000; Hartung 2002; Lencioni 2005, 2013, 2017; Machado 1988, 2006; Machado & Bedê 2006; De Marmels 1987, 2001; Santos 1970; Stefani-Santos et al. 2021; Williamson 1919). We present a detailed description of the 20th female from group A, contributing to the knowledge and distinction of this species, and providing insights for future taxonomic discussions involving females of the genus.