Leptogenys imperatrix

Specimens have been taken mostly in humid forests, including litter from Quercus Linnaeus, 1753, within or beneath rotten logs, but some records are from open pasture.

Identification
Lattke (2011) - Body with abundant piligerous punctae, metanotal groove well impressed, propodeum unarmed; node in dorsal view elongate, wedge shaped; anterior margin less than half the width of posterior margin, lateral margin concave anterad. Body dorsum with abundant decumbent pilosity, and very sparse standing hairs except on head.

A member of the luederwaldti species group. This species has as a distinctive character the presence of a mesonotal depression, usually sulcus shaped, which can be situated anterad, posterad or mesad on the mesonotum, and of variable length.

Distribution
The range of Leptogenys imperatrix extends from Honduras to Panama.

Distribution based on Regional Taxon Lists
Neotropical Region: Costa Rica, Ecuador, Guatemala, Honduras, Panama.

Biology
Longino Ants of Costa Rica - Specimens have been taken mostly in humid forests, including Quercus litter, within or beneath rotten logs, and some records from open pasture. Mann (1922) examined a queen and found it to be quite similar to the worker, with the usual differences in petiole shape and enlarged gaster. This species is relatively common in Monteverde; Longino has collections from four nests, and have seen several other nests from which no collections were made. The colonies are small, and nests are always underground, either with an entrance that is a simple hole at the surface, or emerging into chambers beneath a stone or dead wood. For example, a dead log was turned and workers grabbed brood and vanished down a tunnel. The tunnel extended down about 10cm to a bottom chamber, where only 5 adults, 1 pupa, and 3 larvae were found. Isopods appear to be the main component of the diet, because the nests are usually surrounded by refuse piles of bleached isopod shells. Nests are easy to discover in road banks because there is a telltale whitish-gray streak of isopod shells that pour down the slope from the nest entrance. Longino once excavated a colony and kept it alive for several weeks, offering it a variety of prey. Foragers would take only isopods. Counter to this observation, however, was a worker Longino captured running across the road carrying a spider as prey.

Castes
Queen not examined. Male unknown.

Nomenclature

 *  imperatrix. Leptogenys (Lobopelta) imperatrix Mann, 1922: 15, fig. 8 (w.q.) HONDURAS. See also: Lattke, 2011: 184.

Worker
Lattke (2011) - Metrics (n = 7) : HL 1.82 – 2.02; HW 1.21 – 1.31; ML 0.91 – 1.01; EL 0.40 – 0.51; SL 2.12 – 2.42; PW 1.01 – 1.11; WL 2.93 – 3.33; PH 1.01 – 1.11; PL 1.01 – 1.31; DPW 0.61 – 0.61 mm. CI 0.63 – 0.68; MI 0.69 – 0.77; OI 0.31 – 0.38; SI 1.75 – 1.85; LPI 0.77 – 1.10; DPI 0.46 – 0.60.

Head elongate in full-face view, wider anterad than posterad, lateral margin broadly convex, posterior margin straight, vertexal carina narrow and visible throughout posterior margin; median clypeal lobe triangular and prominent, longer than oculomalar distance, apex bluntly rounded, sometimes with small median lobe. Scape surpassing posterior cephalic border by over one-third its length, finely punctulate; second antennal segment approximately one-half length of third; third antennal segment more than 4 × longer than wide, fourth antennal segment more than half the length of third. Eye strongly convex, diameter at least one-third lateral cephalic margin. Mandible with external and basal margin mostly parallel, weakly widening apicad, strongly bent ventrad close to masticatory border; dorsal surface with weak fine striae; masticatory margin weakly concave and edentate except for apical tooth; PF: 4,3. Tentorial pit apparent, frontoclypeal suture fine but distinct. Clypeus with fine longitudinial striae; frons with abundant punctae, head mostly smooth between eye and clypeus; ventral cephalic surface mostly smooth and shining with sparse weak fine striae. Prementum mostly smooth and shining; stipes varies from mostly smooth and shining to weakly striate.

Mesosoma with broadly convex dorsal pronotal margin in lateral view, mesonotal dorsal margin may form continuous convexity with pronotal margin or may be separated by brief drop; metanotal groove well impressed; propodeal dorsal margin broadly convex; length of declivitous margin one-third of dorsal margin. Mesopleuron with fine transverse striae, metapleuron transversely to obliquely striate-punctate; dorsal propodeum mostly punctate-striate, mostly punctate anterad, mostly striae posterad, declivity transversely striate, spiracle elongate. Pronotum mostly densely punctate, punctae sparse posterolaterad; mesonotum slightly wider than long in dorsal view, punctate, with median longitudinal depression of variable length. Mesosternum with fine transverse, parallel costulate; mesosternum separated from mesopleuron by short crest; bullae bulging. Propleuron mostly smooth and shining, with scattered punctae, and transverse striae anterad.

Petiole triangular in lateral view, with single broadly convex to straight anterodorsal margin, highest posterad, posterior margin broadly convex to straight, dropping at slight angle. Node punctate dorsad and dorsolaterad; most of lateral face and posterior face smooth and shining. Node in dorsal view elongate, wedge shaped; anterior margin less than half the width of posterior margin, lateral margin concave anterad. Postpetiole mostly punctate, punctae becoming progressively sparser on abdominal tergites IV and V. Pygydium with median longitudinal crest, variable in length. Procoxa mostly smooth and shining in lateral view, scattered punctae present dorsolaterad. Body dorsum with abundant decumbent pilosity, and very sparse standing hairs except on head. Mandible, funiculus, tarsi, and gastral apex light brown to ferruginous; coxae, femora and tibiae mostly dark brown; head, mesosoma, petiole and most of gaster black.

Queen
Lattke (2011) - Mann (1922) examined a queen and found it to be quite similar to the worker, with the usual differences in petiole shape and enlarged gaster.

Type Material
Lattke (2011) - Syntype workers: Honduras, Lombardia, San Juan Pueblo, ii.– iii.1920, Cat. No. 24443 (W.M. Mann) ; Cat. No. 20509 [examined].

The MCZC has 2 pins of syntypes with 3 workers on each, and the has 3 workers on a single pin.

References based on Global Ant Biodiversity Informatics

 * INBio Collection (via Gbif)
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Lattke J. E. 2011. Revision of the New World species of the genus Leptogenys Roger (Insecta: Hymenoptera: Formicidae: Ponerinae). Arthropod Systematics and Phylogeny 69: 127-264
 * Longino J. T. L., and M. G. Branstetter. 2018. The truncated bell: an enigmatic but pervasive elevational diversity pattern in Middle American ants. Ecography 41: 1-12.
 * Ryder Wilkie K.T., A. L. Mertl, and J. F. A. Traniello. 2010. Species Diversity and Distribution Patterns of the Ants of Amazonian Ecuador. PLoS ONE 5(10): e13146.doi:10.1371/journal.pone.0013146