Leptogenys linearis

This species inhabits mostly mesic to occasional dry forests of the Amazon watershed, with nests found in rotting logs on the ground (Wheeler 1923).

Identification
Key to Leptogenys of the New World

Lattke (2011) - Head mostly smooth and shining dorsad with abundant piligerous punctulae and appressed pubescence; eye dorsolaterally situated on head, occupying close to one-third lateral cephalic margin, broadly convex; mandibular dorsum with fine longitudinal strigulae and blunt tooth between internal and masticatory margins; mesosternum with two prominent lobes anterad of mesocoxae.

Distribution
Known from Amazon-Orinoco watershed (Brazil, Colombia, French Guiana, Guyana, Peru, and Suriname).

This taxon was described from Brazil.

Castes
Queens and males are unknown.

Nomenclature

 *  linearis. Ponera linearis Smith, F. 1858b: 96 (w.m.) BRAZIL. Combination in Leptogenys: Borgmeier, 1923: 75. Senior synonym of dasygyna: Lattke, 2011: 230.
 * dasygyna. Leptogenys (Lobopelta) dasygyna Wheeler, W.M. 1923d: 8, fig. 3 (w.q.) GUYANA. Junior synonym of linearis: Lattke, 2011: 230.

Lattke (2011) - The common trend in this genus towards smooth and shining sculpture and loss of pubescence is not reflected in this species. The phylogenetic analysis suggests this species is the sister taxon to the rest of the New World Leptogenys.

Worker
Lattke (2011) - Metrics (n = 5): HL 0.51 – 0.53, HW 0.35 – 0.36, ML 0.23 – 0.25, ED 0.50 – 0.54, SL 0.10 – 0.11, WL 0.76 – 0.81, PH 0.25 – 0.28, PNL 0.24 – 0.25, PNW 0.19 – 0.21 mm. CI 0.67–0.69, MI 0.63–0.69, SI 1.46–1.50, OI 0.29 – 0.31, NI 0.79 – 0.88.

Head weakly rectangular in full-face view, lateral margin weakly convex, posterior margin straight to weakly concave; median clypeal lobe broadly triangular, apex rounded, with 2–3 apical setae, clypeus mostly striate, except for smoother median area; lateral lobe weakly developed. Head mostly smooth and shining dorsad with abundant piligerous punctulae and appressed pubescence; frontal carinae extend posterad close to mid-height of eye. Eye dorsolaterally situated on head, occupying close to one-third lateral cephalic margin, broadly convex, closer to lateral cephalic mid-length than to mandibular insertion. Ventral face of head mostly smooth and shining with sparse punctae, pubescence lacking. Scape surpasses posterior cephalic border by over one-fourth its length, scape densely punctulate with abundant decumbent pilosity and scattered subdecumbent hairs. Funicular segments elongate, wider apicad than basad; apical width of third antennal segment under half its length; antennal segments II–IV similar in length, III longer than II and IV. Mandible elongate in cephalic full-face view, basal and external margins subparallel; basal margin mostly broadly convex, masticatory margin weakly concave, blunt basal tooth present. Dorsum mostly striate with scattered punctae, smooth apicad; PF: 4,4.

Mesosoma with dorsal margin forming single broad convexity in lateral view, declivitous propodeal margin broadly convex, curving onto weakly convex declivitous margin with jagged aspect towards tooth. Metanotal groove weakly impressed. Pronotum mostly smooth and shining with abundant piligerous punctulae, punctulae more dispersed on discal area; propleuron mostly smooth and shining; mesopleuron elongate, rectangular with rugulose anepisternum and katepisternum with transverse striae most developed ventrad; metapleuron with transverse striae anterad and posterad, median area smoothened; mesometapleural suture well impressed, scrobiculate; metapleural-propodeal suture developed as ridge that extends anterad variable distance from propodeal spiracle; propodeal declivity with transverse striae anterad of teeth, smooth posterad of teeth; propodeum close to spiracle striate; spiracle elongate, facing posterolaterally with broad sulcus that extends briefly posterad to bulla. Mesonotum wider than long in dorsal view, mesosomal dorsum mostly smooth and shining with abundant punctulae which become sparse close to declivity. Mesosternum with two prominent lobes anterad of mesocoxae.

Petiolar node subquadrate in lateral view, anterior margin vertical, shorter than arched posterior margin, dorsal margin convex, highest posterad. Node subtriangular in dorsal view, width of anterior margin less than half width of posterior margin, lateral margin weakly concave. Node mostly smooth and shining with abundant punctae on dorsum, petiolar sides can be weakly convex in some specimens, or straight ventrad but weakly convex dorsad on the sides; anteroventral process shaped as rectangle with posterior end wider than anterior end in lateral view. Anterior postpetiolar margin weakly convex in lateral view, mostly vertical or anterodorsal margin weakly overhanging basal margin; dorsal postpetiolar margin weakly convex, constriction between abdominal segments III and IV weak; gaster smooth and shining with sparse punctulae. Abundant appressed pubescence present on head and most of mesosoma except for posterior propodeum. Gaster with sparse fine decumbent pubscence and scattered suberect hairs, mostly posterad. Body mostly black with blue opalescence; mandible, clypeus, antennae, legs, and gastral apex brown to dark brown. Metacoxal dorsum with weak posterobasal swelling; tibiae without apical setae.

Type Material
Lattke (2011) - Ponera linearis. Syntype workers: Brazil, Amazonas, Santarem (H.R. Bates) [examined].

Leptogenys (Lobopelta) dasygyna. Syntype workers and queens: Guiana (= British Guiana), Kartabo, 20.vii.1920, nest in rotten log, Cat. No. 3–5, 20504 (W.M. Wheeler) [examined].

Towards the end of this revision I was alerted by Barry Bolton that the worker syntypes of L. linearis were in the. Fortunately it was possible to examine a worker and determine without a doubt that it is the senior synonym of L. dasygyna. The following information was supplied by B. Bolton: “The BMNH has three syntypes (2 workers and 1 male). These are each mounted to card by a slender pin through the mesosoma, and the card itself has a stout pin run through one end. Data label has “Santarem, 54/63”, which in the BMNH Accessions Register reads “1854, no. 63 (11 Oct.). Brazil, Santarem on the Amazon. Purchased from Stevens, collected by Mr Bates, Alta de Chai, nr. Santarem.” A blue card rectangle on each pin states “165”. A further syntype male is in UM, Oxford. This has been remounted in the past by removal of the narrow pin through the mesosoma and then gummed flat onto a square of card, with back of head damaged. On the underside of the card is inscribed, “Braz. Santarem”, and on the upper side the number “165”. Also on the pin are three labels, the uppermost of which is a rectangle of blue card (also present on the three BMNH syntypes). The second states “Ponera linearis Smith”, and the third “Smith Coll. Form. 96.” These 4 specimens appear to constitute the entire syntype series.

Additional References

 * [[Media: Lattke 2011.pdf|Lattke, J.E. 2011. Revision of the New World species of the genus Leptogenys Roger (Insecta: Hymenoptera: Formicidae: Ponerinae). Arthropod Systematics & Phylogeny, 69, 127-264. PDF]]