Leptogenys pinna

Identification
Key to Leptogenys of the New World

Lattke (2011) - A member of the famelica species group. Eye broadly convex, occupies approximately one-fourth of lateral cephalic margin; mesosoma slender with strong constriction at metanotal groove; mesonotum longer than wide; anterior carina of mesopleuron projects laterally as small hooked fin; petiolar node elongate with long anterodorsal margin in lateral view.

L. pinna is different from other species of group because of the elongate mesonotum and petiolar node, well-developed anterior mesopleural process, and the marked constriction of the mesosoma in lateral view, making it look like a slender hour glass.

Distribution
This taxon is known from Costa Rica.

Castes
Male unknown.

Nomenclature

 *  pinna. Leptogenys pinna Lattke, 2011: 170, fig. 26 (w.q.) COSTA RICA.

The unusual irregular “bumps” on the queen propodeum and anterior node face, or similar sculpturing, are not present in other species, leading to believe they could be individual deformities of the specimen.

Worker
Metrics, holotype (paratypes, n = 2): HL 1.42 (1.31-1.38); HW 0.91 (0.88-0.88); ML 0.81 (0.78-0.81); EL 0.30 (0.27-0.30); SL 2.16 (1.99-2.09); PW 0.81 (0.84-0.84); WL 2.90 (2.86-2.90); PH 0.84 (0.94-0.94); PL 0.91 (0.94-1.01); DPW 0.61 (0.61-0.61) mm. CI 0.64 (0.63-0.67); MI 0.89 (0.88-0.92); OI 0.33 (0.31-0.35); SI 2.37 (2.27-2.38); LPI 0.93 (0.93-1.00); DPI 0.67 (0.60-0.64).

Head elongate in full-face view, wider anterad than posterad; lateral cephalic margin broadly convex; posterior cephalic margin convex; median clypeal process triangular, laminate, apex pointed; lateral clypeal process narrow, forming small angle with base of median process. Eye broadly convex, occupies approximately one-fourth of lateral cephalic margin, situated slightly dorsolaterally, anterad of mid-length of lateral cephalic margin. Cephalic dorsum mostly smooth with abundant punctulae, and scattered piligerous punctae; clypeus mostly smooth medially with oblique to longitudinal striae laterad; longitudinal sulcus extends posterad from between frontal carina to one-half eye height; clypeus and frontal carina protrude dorsally in lateral view, clypeal margin broadly convex; head ventral surface smooth and shining with sparse punctae. Scape densely punctulate, with abundant subdecumbent pilosity and scattered subdecumbent to suberect hairs, scape extends beyond posterior cephalic margin by over half its length; third antennal segment over 4 x longer than apical width, second antennal segment almost half length of third segment; fourth antennal segment over half length of third segment, funicular segments subcylindrical. Mandible elongate, triangular, masticatory margin concave, basal half serrate, apical half edentate, length of masticatory margin almost same as basal margin; dorsal mandibular surface smooth with scattered punctae.

Mesosoma slender, markedly constricted with deep metanotal groove separating convex promesonotal margin in lateral view from broadly convex dorsal propodeal margin; mesosomal sculpture mostly smooth and shining with scattered piligerous punctae. Mesometapleural suture partially to totally scrobiculate, well impressed along mesopleuron; metapleural-propodeal suture lacking; propodeal spiracle not elevated, elongate, oriented laterally to slightly posterad; bulla of metathoracic spiracle convex, not abruptly circumscribed by sulcus; mesopleuron mostly with weak fine transverse striae, striae usually colliculate, anterodorsally mostly smooth; anteroventral carina well developed, forming prominent angular, laminate lobe anterad, in dorsal view lobe resembles small fin; mesosternum with transverse striae anterad; metapleuron with transverse striae posteroventrad; declivitous propodeal face mostly transversely striate, bulla strongly convex; propodeum rounded, without lateral lobe or tooth; mesonotum longer than wide in dorsal view, anterior margin convex; metanotal groove straight, with irregular sculpture, not scrobiculate.

Petiole elongate, subtriangular in lateral view, anterior margin brief and concave; anterodorsal margin convex, longer than posterior margin; node highest posterad; posterior margin broadly convex. Transverse section of node at mid-length has convex lateral outline. Subpetiolar process angular, posterad with projecting lobe in lateral view. Node elongate in dorsal view, anterior margin convex, half width of posterior margin; lateral margin broadly convex, posterior margin straight. Node smooth and shining, posterior face not sharply separated from lateral face. Anterodorsal postpetiolar margin convex in lateral view; gaster with scattered punctulae, constriction between abdominal segments III and IV weak; procoxae smooth and shining in lateral view. Mesosoma with no pilosity, only scattered standing to suberect hairs; decumbent to appressed pilosity present on cephalic dorsum, ventral coxal faces, femora, tibiae, and tarsi; gaster with scattered subdecumbent pilosity. Head, mesosoma, node and most of gaster black; antenna, mandibles, clypeus, legs and apex of gaster brown, coxae dark brown. Apex of protibia without setae; meso and metatibial apex with single external seta.

Queen
Metrics: HL 1.48; HW 0.94; ML 0.74; EL 0.30; SL 2.06; PW 0.84; WL 2.70; PH 0.88; PL 0.88; DPW 0.64 mm. CI 0.64; MI 0.79; OI 0.32; SI 2.18; LPI 1.00; DPI 0.73. The queen is ergatoid with the usual differences from the workers except for the dorsal propodeal margin, which in lateral view presents a brief convexity, shaped as a distinct “hill”, and posteriorly it curves smoothly onto the declivitous margin. There is a vestigial median ocellus. The petiolar node likewise has a brief convexity on the anteroventral margin. The queen is lighter colored than the worker with a more ferruginous tint.

Type Material
Holotype worker. Costa Rica, Río Reventazón, 3 – 5 km E Turrialba, 19. – 22.i.1973, W.L. Brown, deposited in. – Paratypes. Same series as holotype. 1 queen and 2 workers deposited in MCZC.

The pin with the holotype has two point-mounted ants, the bottom ant was designated as the holotype, and its point was partially stained red. The top ant is the queen.

Etymology
The species name is the Latin noun for fin and alludes to the fin-like anteroventral mesopleural process.