Octostruma leptoceps

Octostruma leptoceps
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Attini
Genus:	Octostruma
Species:	O. leptoceps
Binomial name
Octostruma leptoceps Longino, 2013 Specimen Label

This is known from a single worker collected in mesophyll cloud forest at 1290 m elevation. The specimen was in a sample of sifted leaf litter from the forest floor.

Identification

Basal five teeth of mandible acute; labrum triangular with straight, evenly converging sides, anterior lobes converging and confluent at apex, such that labrum apex is blunt but not distinctly bilobed; head very narrow, CI 94. (Longino 2013)

Keys including this Species

• Key to Octostruma species

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: 15.4894° to 15.4881761°.

North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

• Source: AntMaps

Distribution based on Regional Taxon Lists

Neotropical Region: Honduras (type locality).

Distribution based on AntMaps

Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.

Biology

Explore Overview of Octostruma biology  Longino (2013) - Brown and Kempf (1960) summarized the biology of basicerotines as follows: The basicerotines all come from tropical or subtropical areas, and predominantly from mesic habitats, particularly rain forest, where they live primarily in the upper layers of the soil and in the soil cover, including large and small pieces of rotten wood. They are fairly common in soil cover berlesates. Nests have been found in snail shells, and in the peaty masses gathered about epiphytic ferns above the ground level. So far as is known, colonies are small, consisting of one or more dealate—or rarely ergatoid—females, and a few workers. Judging from the structure of the workers and females, one would suppose that they were predaceous on small arthropods... Besides this summary, the behavior of three basicerotine species has been studied. Wilson (1956) observed a small captive colony of Eurhopalothrix biroi, a New Guinea species. Workers moved slowly and captured a variety of small, soft-bodied prey, including spiders, symphylans, entomobryid Collembola, campodeids, and hemipteran nymphs. Wilson and Brown (1984) observed a captive colony of Eurhopalothrix heliscata, a species from Singapore. The colony contained over 400 workers, multiple alate and dealate queens, several adult males, and brood. Foraging workers acted "rather like miniature ferrets," readily wedging themselves into small crevices. They foraged solitarily, attacking a variety of prey but mostly termites. They used their sharply-toothed mandibles to abruptly snap onto appendages of prey, maintaining purchase and slowly reaching around with the gaster to sting the prey. The strongly sclerotized labrum was also employed to press against the clamped appendage. The behavioral repertoire was limited. There did not appear to be trophallaxis, as workers and larvae fed directly from prey in the brood chambers. Nor did there appear to be any form of alarm communication. While there was generally an increase in the number of foragers when clusters of prey were presented, there was no evidence of any pheromone-based recruitment. Workers were non-aggressive and responded to disturbance by tucking the appendages and becoming immobile, often for minutes at a time. Wilson and Hölldobler (1986) studied captive colonies of Basiceros manni from Costa Rica and observed behavior not substantially different from E. heliscata. Foraging workers of many basicerotines are often encrusted with a firmly bonded layer of soil, which is thought to function as camouflage, enhancing crypsis (Hölldobler & Wilson, 1986). Knowledge of the basic natural history of these ants has hardly progressed since the observations of Wilson, Brown, and Hölldobler. More specimens are now available for examination due to quantitative litter sampling, enhancing knowledge of basicerotine diversity and distribution, but discovering nests remains exceedingly difficult. Quantitative samples of 1 m2 litter plots reveals that small basicerotines can be very frequent, occurring in over 50% of samples in some cases, but never in large numbers. Individual samples usually contain fewer than ten workers, and workers are often accompanied by dealate queens. These results suggest that colonies, at least among New World species, are usually small, with tens of workers. Less than half of the species of Octostruma have their queens described. Ergatoid queens are known from some species. Males are known from collections for some species but none have been described. The mating biology of these ants and how common ergatoid queens are across the genus and within colonies is not known. ‎

Castes

Known only from the worker caste.

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

• leptoceps. Octostruma leptoceps Longino, 2013: 38, figs. 1A, 5H, 28, 43 (w.) HONDURAS.

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

Description

Worker

HW 0.68, HL 0.73, WL 0.87, CI 94 (n=1); Labrum sides straight, strap-like lateral portions converging from base to apex, apex bluntly rounded, not bilobed; mandible triangular, in profile view with mandible closed, base in same plane as clypeus, evenly curved downward toward apex; mandibles closed on holotype, but basal teeth visible, acute, tooth 1 continuous with basal rim of dorsal surface; dorsal surface of mandible roughened; ventral surface flat, smooth and shining; interior surface concave, smooth and shining; scape with pronounced anterobasal lobe, dorsal surface smooth, matte; clypeus with broad, shallow emargination anteriorly; clypeus smooth, sublucid, with sparse puncta; face uniformly irregularly rugose; frontal carinae faint, nearly obsolete; antennal socket deep, dorsal rim of socket continuous with pronounced dorsal margin of antennal scrobe; antennal scrobe deep, strongly delimited dorsally, posteriorly, and ventrally with sharply defined thin cuticular rim; compound eye small, circular, composed of about 7 ommatidia; distinct carina extends from ventral margin of antennal socket across floor of scrobe to compound eye; scrobe floor matte; vertex margin anterior to occipital carina smooth, matte (top of head, not visible in face view); occipital carina extends anteriorly on ventral surface of head about to level of compound eye; postgenal suture visible as impressed line on undersurface of head; undersurface rugulose.

Promesonotum moderately convex in profile, promesonotal suture moderately impressed; metanotal groove not impressed; propodeum with distinct dorsal and posterior faces; dorsal face weakly convex; propodeal spines well-developed, acute, laterally flattened, extending ventrally as thin carinae; propodeal spiracle somewhat protruding, located below propodeal spine, not quite abutting posterior margin, diameter about equal to width of base of propodeal spine; all surfaces of mesosoma matte; entire promesonotum irregularly rugose, with similar sculpture to face; mesopleuron and side of propodeum confluent; entire mesopleuron and propodeum smooth.

Petiole in profile with peduncle differentiated from node, node with distinct anterior face; posterodorsal face of node an even convexity; anteroventral margin with anteriorly-directed tooth subtended by short posterior flange; postpetiole low, broad, weakly crescent-shaped in dorsal view; dorsum of petiolar node and postpetiole punctatorugose; first gastral tergite and sternite densely punctate, interspaces smooth and shining, tergal puncta smaller posteriorly; first gastral sternite strongly convex, with prominent blunt medial keel.

Anterior labral lobe with radiating tuft of soft, thick, translucent, capitate setae of unequal length projecting from apex; each larger mandibular tooth with fully appressed seta running length of tooth; anterior margin of scape with about nine stiff clavate setae; clypeus, face, promesonotal dorsum, petiolar node, and dorsal postpetiole with conspicuous, yellow, appressed ground pilosity of long, thin setae; face of holotype appears largely devoid of erect setae but specimen may have lost setae; a single spatulate seta present on one lateral vertex margin, and what may be a seta near medial vertex margin; mesosomal dorsum lacking erect setae; mesotibia with conspicuous ground pilosity, about 5 spatulate setae of variable length at apex; petiole and postpetiole lacking erect setae; first gastral tergite lacking erect setae, ground pilosity fully appressed, sparse (length of setae less than distance between them); first gastral sternite with abundant spatulate setae clustered on posterior half, anterior half devoid of setae.

Color dark brown.

Holotype Specimen Labels

Type Material

Holotype worker: Honduras, Cortés: PN Cusuco, 15.48940, -88.23621, ±20 m, 1290 m, mesophyll forest, ex sifted leaf litter, 30 May 2010 (LLAMA, Wa-C-06-2-12) California Academy of Sciences, unique specimen identifier CASENT0617645.

Etymology

The name refers to narrow head relative to other species. It is a noun in apposition and thus invariant.

References

• Longino, J.T. 2013. A revision of the ant genus Octostruma Forel 1912 (Hymenoptera, Formicidae). Zootaxa 3699, 1-61. doi:10.11646/zootaxa.3699.1.1

References based on Global Ant Biodiversity Informatics

• Longino J. T. 2013. A revision of the ant genus Octostruma Forel 1912 (Hymenoptera, Formicidae). Zootaxa 3699(1): 1-61.
• 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.