Leptogenys ritae

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Leptogenys ritae
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Ponerinae
Tribe: Ponerini
Genus: Leptogenys
Species: L. ritae
Binomial name
Leptogenys ritae
Forel, 1899

Leptogenys ritae casent0178801 profile 1.jpg

Leptogenys ritae casent0178801 dorsal 1.jpg

Specimen labels

Synonyms

Collection sites include both dry and humid forests as well as coffee and cocoa plantations. Two nests are described from beneath partially buried stones. The adults flee quite rapidly upon discovery of the nest.

Identification

Key to Leptogenys of the New World

Lattke (2011) - A member of the pusilla species group. Eye placed anteriorly on side of head, greatest diameter with 6 ocelli, separated from posterolateral clypeal margin by less than one diameter. Node elongate in dorsal view, anterior margin convex, a bit more than half the width of the posterior margin, post margin straight, lateral margins straight to slightly convex.

Keys including this Species

Distribution

This species is found from Panama into northern South America, including Trinidad, and south into Colombia and Ecuador.

Distribution based on Regional Taxon Lists

Neotropical Region: Colombia, Ecuador, Panama (type locality), Trinidad and Tobago, Venezuela.


Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

The biology of Leptogenys ritae 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

Nomenclature

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

  • ritae. Leptogenys ritae Forel, 1899c: 17 (w.) PANAMA. Lattke, 2011: 198 (m.). Senior synonym of panamana, venatrix: Lattke, 2011: 198.
  • panamana. Leptogenys (Lobopelta) pusilla var. panamana Wheeler, W.M. 1923d: 14 (w.) PANAMA. Junior synonym of ritae: Lattke, 2011: 198.
  • venatrix. Leptogenys venatrix Forel, 1899c: 17 (w.) PANAMA. Junior synonym of ritae: Lattke, 2011: 198.

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

Lattke (2011) - Throughout much of its range the morphology is relatively uniform, with gradual changes as one travels from one region to another, though some specimens suggest the existence of more than one species. Specimens from Panama have slightly more robust mandibles, a slightly longer mesonotum and laterally facing propodeal spiracles, with a shallow depression posterad of the spiracle. The scape of the ants from Trinidad is a bit longer than those from neighboring Venezuela. Specimens from Trujillo, Venezuela are smoother than those from eastern Venezuela, and show a relatively straight mesosomal dorsal margin in lateral view. Northern Colombian specimens have weak parallel striae on the metapleuron. The opening of the propodeal spiracle becomes laterally directed in specimens from Trujillo, Venezuela and localities westward, down into Ecuador. The specimens from Tiputini, Ecuador and southern Colombia (Nariño, Vaupés, and Caquetá) present a more slender median clypeal lobe with a rounded apex, and additionally a transverse section of the node at mid-length is laterally more rounded, and the head is more ovoid in full-face view. The ant from Santander, Colombia could represent another species due to its more elongate head, cephalic punctuation, elongate third antennal segment, and more acutely pointed propodeal armature, but it is only one specimen, and not in the best of shape so more material should be accumulated before judging its status.

Immediately after the description of L. ritae Forel (1899: 17) describes L. venatrix from an unspecified number of workers taken in the same locality as L. ritae. Curiously the description of L. venatrix fits more an ergatoid queen than a worker, and the diagnostic characters that Forel (1899: 18) uses to separate L. venatrix from L. ritae correspond with those typical of an ergatoid queen: more robust body, squamiform petiole, and larger eyes. Given that multiple queen nests of L. ritae have been recorded (see section 5.3. Reproduction), it seems likely the specimens Forel studied to describe L. venatrix were actually queens and not workers as he assumed. They might even be part of the nest series of L. ritae. Ironically on the same page he noted Leptogenys queens were unknown and probably apterous. The only type specimen I could examine for L. venatrix is a queen in the Museo Civico di Storia Naturale, Genoa, and I found nothing that could justify separating it from L. ritae. Wheeler (1923: 14) describes L. panamana as a variety of Leptogenys pusilla based upon differences in color and density of pubescence, but an examination of the type reveals it is actually L. ritae.

There seems to be two types of queens in this species, one with the normal modifications expected of the gyne, whilst the other type is easily distinguished by its remarkably hypertrophied, pale yellow mandibles. The possibility the two queens represent different species exists, but this is apparently not reflected by worker morphology. The role of the enlarged mandible is unknown though it might be associated with the presence of glands. The possibility of parasitism can not be ruled out. Queens of the latter type are known from Caripe, Venezuela. They come from two apparent nests (numbers 1017 and 1018) taken only 80 cm apart from each other. Each series has a single queen of the enlarged mandible type, but neither nest was completely collected. Number 1017 was taken from a rotten log beneath the leaf litter, but no detailed information is given for 1018 in Lattke’s field book. The short distance separating the two implies they could be components of the same nest. The existence of 2 normal queens in the series from Trujillo, Venezuela implies either polygyny or the presence of virgin queens that will eventually abandon the mother nest. Natural history studies as well as molecular methods would probably help to unravel the mystery behind the two types of queens.

Description

Worker

Lattke (2011) - Metrics (n = 8) : HL 0.75 – 0.84; HW 0.52 – 0.57; ML 0.35 – 0.42; EL 0.07 – 0.12; SL 0.62 – 0.75; PW 0.35 – 0.50; WL 1.04 – 1.24; PH 0.43 – 0.50; PL 0.38 – 0.48; DPW 0.28–0.33 mm. CI 0.62–0.71; MI 0.65–0.81; OI 0.13 – 0.21; SI 1.16 – 1.45; LPI 1.00 – 1.13; DPI 0.64 – 0.78.

Head elongate in full-face view, sides semi-parallel; lateral margin broadly convex; posterior cephalic margin weakly convex, almost straight; anterior clypeal margin with triangular median lobe, gradually tapering to acute point, usually with single apical seta; lateral clypeal lobe narrow, expanding as modest lobes close to median lobe; cephalic dorsum mostly smooth and shining with sparse punctulae; eye about same length as mid-width of scape; eye anteriorly placed on side of head, elliptical, greatest diameter with 6 ocelli, separated from posterolateral clypeal margin by less than one diameter; head widest posterior to compound eyes, eyes slightly converge anterad, cephalic width slightly less anterad of eyes. Scape smooth with abundant piligerous punctae, surpasses posterior cephalic border by two apical widths; antennal segments III – IV same length, segment II slightly longer; width of each segment more than half respective length. Mandible elongate, basal and external margins subparallel, basal margin broadly mostly convex with brief concavity next to brief masticatory margin, basal convexity with row of 2 – 3 setae; dorsal surface smooth and shining with sparse punctae.

Mesosoma with dorsal margin relatively continuously broadly convex, or at most forming two weak convexities in lateral view, slight depression present at metanotal groove; dorsal propodeal margin approximately twice the length of declivity, the two margins form broadly curved angle, declivitous margin ends at apex of blunt, modest triangular lobe at spiracular height. Pronotum mostly smooth and shining with narrow band of transverse striae on anterior face, mesonotum transverse and narrow in dorsal view, 3 – 4 × wider than long; propodeal dorsum mostly smooth and shining with scattered, posterior facing piligerous punctae and traces of transverse imbricate etchings, declivity with transverse fine striate. Meso-metapleuron ranging from colliculate to rugulose or striate, striae curved or straight, raised lineations slightly undulate or asperous; metapleural-propodeal suture absent; propodeal spiracle round, posterolaterally facing, with depression posterad of spiracle; mesopleuron with fine anteroventral carina, mesosternum with low transverse striae.

Petiole node subquadrate in lateral view; anterior margin less than half height of posterior margin, node highest posterad, dorsal margin convex, without sharp lateral edges; lateral node face mostly smooth and shining with irregular to transverse striae or folds, mostly anteroventrad; subpetiolar process triangular in lateral view. Node elongate in dorsal view; anterior margin convex, width slightly more than half width of posterior margin, posterior margin straight, lateral margins straight to slightly convex. Anterior margin of postpetiole vertical, broadly convex to straight, joined by broad angle with broadly convex dorsal margin; dorsal margin of postpetiole convex. Gaster mostly smooth and shining, abdominal tergite III with scattered punctulae, tergite IV dorsad with posteriorly scalloped punctae, laterad punctulate with some punctae anterad; constriction well developed. Procoxa smooth and shining in lateral view. Body mostly black to ferruginous dark-brown; gastral apex ferruginous brown; antennae, clypeus, mandibles, and legs ferruginous; clypeus and coxae darker. Cephalic dorsum with abundant short suberect hairs, body with scattered subdecumbent hairs; no applied pilosity.

Queen

Lattke (2011) - Metrics: “Normal” queen (n = 2): HL 0.82 – 0.84; HW 0.55 – 0.58; ML 0.37 – 0.40; EL 0.08 – 0.12; SL 0.67 – 0.68; PW 0.47 – 0.47; WL 1.09 – 1.10; PH 0.45 – 0.47; PL 0.33 – 0.42; DPW 0.28 – 0.35 mm. CI 0.67 – 0.70; MI 0.67 – 0.69; OI 0.15 – 0.20; SI 1.17 – 1.21; LPI 1.08 – 1.40; DPI 0.68 – 1.05. “Mandibular” queen (n = 2): HL 0.82–0.84; HW 0.58–0.58; ML 0.42–0.45; EL 0.12 – 0.12; SL 0.68 – 0.72; PW 0.45 – 0.47; WL 1.09 – 1.12; PH 0.47 – 0.47; PL 0.40 – 0.40; DPW 0.33 – 0.33 mm. CI 0.70–0.71; MI 0.71–0.77; OI 0.20–0.20; SI 1.17 – 1.23; LPI 1.17 – 1.17; DPI 0.83 – 0.83. Usual differences from worker: Head longer than wide, ovoid in full-face view, posterior margin convex; propodeal dorsal margin convex in lateral view, declivity with low, blunt triangular lobe. Petiolar node triangular in dorsal view, anterior margin narrow, truncate and rounded, lateral margin straight, posterior margin weakly convex; node subrectangular in lateral view, slightly inclined anterad, anterior margin shorter than posterior margin, dorsal margin convex. Gaster noticeably enlarged. Two types of queens distinguishable by mandible: (1) mandible same shape and color as in worker; (2) mandible greatly thickened and swollen, pale yellow in color.

Male

Lattke (2011) - Head subglobular in full-face view, eye covers most of lateral cephalic margin, posterior cephalic margin strongly convex; ocelli large, mid ocellus smaller than lateral ocellus. Clypeus extends anterad from inner margin of eye, anterior clypeal margin broadly convex. Mesosoma with flattened dorsal mesonotal margin in lateral view, anterior mesonotal margin brief, convex.

Type Material

Lattke (2011) - Holotype worker: Panama, Colon (C. Emery) (Museo Civico di Storia Naturale, Genoa) [examined].

Leptogenys venatrix. Syntype queens (mistaken for workers in original publication): Panama, Colon (C. Emery) (MCSN) [examined].

Leptogenys (Lobopelta) pusilla var. panamana. Syntype workers and male: Panama, C.Z., Ancon, 10.xi.1911, under stone (W.M. Wheeler) (Museum of Comparative Zoology) [examined].

References