Leptogenys cracens

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Leptogenys cracens
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Ponerinae
Tribe: Ponerini
Genus: Leptogenys
Species: L. cracens
Binomial name
Leptogenys cracens
Lattke, 2011

Leptogenys cracens P.jpg

Leptogenys cracens D.jpg

Specimen Label

Nothing is known about the biology of Leptogenys cracens.

Identification

Lattke (2011) - Head elongate in full-face view; compound eye small, not more than 3 ommatidia in length, distance from ocular midpoint to mandibular insertion greater than that from eye to mid-distance of lateral cephalic margin, mandible subtriangular, basal margin with convex lobe basad, row of 4 setae present next to base of median lobe; petiole pedunculate in lateral view, peduncle half as long as node length; node subquadrate; constriction between abdominal segments III and IV strongly marked, with longitudinal striae.

A very singular species on account of the pedunculate petiole (the only New World species with such a petiole), mandibular structure, slender clypeal lobe and the strong constrictions at the metanotal groove as well as between abdominal segments III and IV.

A member of the ingens species group.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Mexico (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

The biology of Leptogenys cracens is poorly known.

The Leptogenys genus page has more details about the general biology of ants in this genus, some of which is summarized in what follows. New World species have relatively small ranges, generally occur in humid forests and prey on isopods. Colonies may occur in high densities on a local scale, with up to 5 or 6 species present. Nest size tends to be small with just 20 or 30 individuals in a mature colony. Nests of most species may be found in rotten wood on the ground, usually within cavities in logs or large branches, and also beneath bark. Wood-soil and rock-soil interfaces are another common nesting location, as well as rock crevices, and a few species may nest directly in the soil. Reproduction is most commonly via ergatoid females and, in many species, may include egg-laying workers.

Castes

Queen, male. Unknown.

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • cracens. Leptogenys cracens Lattke, 2011: 228, fig. 82 (w.) MEXICO.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Metrics, holotype: HL 1.12; HW 0.68; ML 0.52; EL 0.08; SL 1.30; PW 0.60; WL 1.70; PH 0.66; PL 0.80; DPW 0.40 mm. CI 0.61; MI 0.76; OI 0.12; SI 1.91; LPI 0.83; DPI 0.50.

Head elongate in full-face view, wider anterad than posterad, lateral cephalic margin mostly straight to weakly convex, posterior margin weakly convex, vertexal carina well developed, narrow, visible along all of posterior cephalic margin; median clypeal lobe slender, basal lateral margin concave, apex pointed, without setae, with 2 preapical long hairs; lateral clypeal lobe narrow, projecting little anterad. Compound eye small, not more than 3 ommatidia in length, placed laterally on head, distance from ocular midpoint to mandibular insertion greater than that from eye to mid-distance of lateral cephalic margin, eye in dorsal cephalic view weakly convex. Cephalic dorsum mostly smooth and shining except for scattered piligerous punctulae. Scape surpasses posterior cephalic border by over one-third its length, lengths of antennal segments II & IV more than twice respective apical widths, each segment wider apicad than basad, lengths of segments II & IV each more than half that of segment III, length of segment III 3 × its apical width. Scape mostly smooth and shining with scattered punctae, no appressed pubescence, with subdecumbent hairs. Mandible subtriangular, basal margin convex with row of 4 setae next to base of median lobe, each seta originating on mandibular dorsum, close to basal margin; masticatory margin edentate except for apical tooth, mandibular dorsum mostly smooth and shining except for scattered piligerous punctae, lateral margin convex.

Mesosoma with broad and well-impressed metanotal groove in lateral view, mesosoma appearing constricted at groove; promesonotal margin continously convex, dorsal propodeal margin weakly convex, more than 2 × length of declivitous margin, declivitous margin broadly convex, propodeal tooth triangular, pointed. Mesosomal side mostly smooth and shining except for irregular imbrications on posterior metapleuron, anteroventral margin of mesopleuron and ventral area with fine striate, mesometapleural suture well impressed, scrobiculate; metapleural-propodeal suture absent, mesopleuron subrectangular, propodeal spiracle broadly elliptical, facing posterolaterad. Mesonotum subquadrate, metanotal suture scrobiculate.

Petiole with anterior peduncle half as long as node length; node in lateral view subquadrate, anterior margin straight, slightly under half length of posterior margin; node highest just posterad of mid-length; dorsal margin broadly convex anterad, more convex posterad; posterior margin straight, inclined. Subpetiolar process subrectangular, posterior margin longer than anterior margin. Node in dorsal view longer than wide, anterior margin convex, width of anterior margin more than half the width of posterior margin, lateral margin broadly convex. Cross-section of node V-shaped, with convex lateral margins.

Anterior margin of abdominal segment III convex in lateral view, with anterior margin overhanging base, dorsal margin convex, constriction between abdominal segments III and IV strongly marked, longitudinally striate on both tergite and sternite, gaster widening posterad of constriction before narrowing again; stridulitrum present on pretergite of abdominal segment IV. Gaster mostly smooth and shining with scattered piligerous punctae and punctulae. Procoxa in lateral view with sparse transverse strigae; tibiae without apical setae; legs relatively long. Head and body without pubescence, only scattered pilosity. Body mostly brown; mandibles, antennae, legs and gastral apex ferruginous brown.

Type Material

Holotype worker. Mexico, Oaxaca, Grutas de Monteflor, 6 km N Valle Nacional, 28.xii.1973, J. Reddell, D. & M. McKenzie, S. Murphy leg. One worker deposited in the Los Angeles County Museum of Natural History.

Valle Nacional is located at 17°46′N 96°18′W, and a cursory exploration on a map of points roughly 6 km north of Valle Nacional show altitudes of 300 – 900 m.

Etymology

The species name alludes to the slender and strikingly gorgeous aspect of the ant. It is Latin for graceful.

References