Eurhopalothrix gravis

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Eurhopalothrix gravis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Eurhopalothrix
Species: E. gravis
Binomial name
Eurhopalothrix gravis
(Mann, 1922)

Eurhopalothrix gravis casent0107554 p 1 high.jpg

Eurhopalothrix gravis casent0107554 d 1 high.jpg

Specimen Labels

Synonyms

Longino (2013): This species occurs in mature to second growth wet forest habitats. It is a lowland species, occurring from sea level to 1100 m in Central America. Many specimens are from Berlese and Winkler samples of sifted litter and rotten wood from the forest floor, but unlike many other species, specimens have also been found by direct search, usually isolated workers under loose bark of rotten wood. An alate queen was collected in a flight intercept trap in Belize, 19–28 August 2007 (P. W. Kovarik). Where it has been collected it is typically low density, occurring in less than 1% of Winkler samples, but one exception was a site at 1100 m elevation on the Barva Transect in Costa Rica, where it occurred in 8% of samples.

Identification

Keys including this Species

Distribution

Southern Mexico to Costa Rica; Brazil (Santa Catarina)?

Distribution based on Regional Taxon Lists

Neotropical Region: Belize, Brazil (type locality), Costa Rica, Dominica, Guatemala, Honduras (type locality), Lesser Antilles, Mexico, Nicaragua, Puerto Rico, Venezuela.

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Little is known about the biology of most species in this genus. Nests are rarely found, and queens and males have not been collected for many species. Longino (2013) summarized their biology "Eurhopalothrix specimens are encountered almost exclusively in samples from mass extraction techniques that recover small arthropods in sifted litter, rotten wood, and soil. Densities, at least in the northern Neotropics, are usually low, with workers occurring in < 10% of quantitative samples of 1 m2 litter plots, but occasionally may reach densities as high as 40% of samples. Live colonies of Old World Eurhopalothrix were observed by Wilson (1956) and Wilson and Brown (1984), and a Costa Rican colony of Basiceros manni was observed by Wilson and Hölldobler (1986). All basicerotines, including Eurhopalothrix, are thought to be predators in tropical leaf litter, relying on stealth or sit-and-wait techniques. Sampled specimens are often coated with a thin layer of clay, especially on the face, which is thought to function as camouflage, enhancing crypsis (Hölldobler & Wilson, 1986). Highly specialized spatulate setae may be instrumental in acquisition and adherence of the clay layer (Hölldobler & Wilson, 1986)."

Castes

Worker

Queen

Nomenclature

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

  • gravis. Rhopalothrix (Rhopalothrix) gravis Mann, 1922: 40, fig. 19 (w.q.m.) HONDURAS. Wheeler, G.C. & Wheeler, J. 1955a: 117 (l.). Combination in Eurhopalothrix: Brown & Kempf, 1960: 211. Senior synonym of reichenspergeri: Brown & Kempf, 1960: 211.
  • reichenspergeri. Rhopalothrix reichenspergeri Santschi, 1923g: 1263 (w.) BRAZIL. Combination in Octostruma: Brown, 1949f: 92. Junior synonym of gravis: Brown & Kempf, 1960: 211.

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

Longino (2013) - The synonymy of E. reichenspergeri under E. gravis and thus the occurrence of E. gravis in southern Brazil should be considered suspect until the South American fauna is better sampled and understood. Brown and Kempf's (1960) concept of E. gravis was considerably broader than the concept adopted here and included several of the new species described in this work.

Description

Worker

Longino (2013) - HW 0.83–0.94, HL 0.75–0.83, SL 0.47–0.54, SLL 0.05–0.07, CI 110–115, SLI 10–14 (n=7). Labrum anterolateral gibbosities of basal portion developed as sharply right-angled, ventrally-directed teeth, apical portion short, flexed dorsally, distinctly bilobed, anterior lobes well separated; apex of each lobe with a fringe of very short translucent setae and 2 longer pointed translucent setae; mandible triangular, dorsal surface convex, minutely punctulate, dull, rounding into ventral surface; interior surface concave, smooth and shining; masticatory margin with two tooth rows, an outer row of 10 flattened, acute teeth, second and third tooth from base larger than other teeth; an inner row of 3 long needle-shaped teeth, behind outer teeth 3–6 and projecting beyond them, nearly 2x length of flanking outer teeth; scape with moderately developed basal lobe; scrobe deep, sharply delimited dorsally and ventrally, abutting deep antennal socket; surface of scrobe weakly foveolate anteriorly, smooth and shiny posteriorly; eye with about 5 ommatidia across greatest diameter; clypeus approximately planar, shallowly roughened, dull; juncture of clypeus and frons impressed; sides of head above eyes strongly angulate; surface of face uniformly convex, shallowly rugulose, anterior frons with moderately developed longitudinal medial carina; occipital carina indistinct; undersurface of head uniformly rugulose; postgenal suture a well-developed longitudinal trough.

Promesonotal profile evenly convex, posterior margin a short step dropping to sloping, flat dorsal face of propodeum; metanotal groove not impressed; dorsal and posterior faces of propodeum distinct, meeting at obtuse angle, dorsal face shorter than posterior face; propodeal spine laminar, translucent, triangular, acute, ventral margin curving into narrow infradental lamella that extends down posterior face to propodeal lobe; propodeal spiracle distinct, directed posteriorly; dorsal promesonotum rugulose; anterior pronotum, upper side of pronotum, anepisternum, dorsal and posterior faces of propodeum punctate; lower sides of pronotum, katepisternum, side of propodeum smooth, clean specimens with a pearly luster; with or without feeble transverse carinulae between propodeal spines.

Petiolar peduncle joins anterior face of petiolar node at rounded obtuse angle; petiolar node subquadrate, anterior face rounding into dorsal face and dorsal face rounding into posterior face; ventral margin of petiole with pronounced, acute anteroventral tooth; postpetiole low and broad, with a shallow longitudinal sulcus dorsally; first gastral sternite lacking anterior sagittal keel; petiole, postpetiole, first gastral tergite covered with dense, small, puncta, interspaces less than or equal to width of puncta; first gastral sternite similar, but puncta and interspaces larger.

Dorsal surface of scape covered with uniform short, appressed, flattened setae; leading edge of scape with projecting setae, shortest near apex, gradually lengthening to longest on basal lobe; ground pilosity uniformly distributed across face, frontal lobes, and clypeus; ground setae on posterolateral face similar to those on scapes, ground setae on medial face and clypeus thinner; undersurface of head with ground setae like those on posterolateral face; projecting specialized setae spatulate, about 3x longer than wide, much larger than ground pilosity and highly differentiated from it, full complement 18, with curved anterior row of 8, transverse median row of 4, and posterior row of 6 on vertex margin; ground setae similar to those on posterolateral face abundant on promesonotal dorsum, dorsal half of propodeal spines, dense on dorsa of petiolar node and postpetiole, much sparser on first gastral tergite; 3 pairs projecting spatulate setae on promesonotum; legs with dense, strongly flattened, appressed to decumbent setae on apices of femora, posterior face of foretibia, entire midtibia, anterior face of hindtibia, somewhat sparser on other surfaces; apex of foretibia with 1 larger spatulate seta, apices of mid and hind tibia with 2; basitarsus and remaining tarsomeres with abundant, spatulate setae; two large spatulate setae on hind margin of dorsal face of petiolar node; row of 4 spatulate setae on hind margin of postpetiole, median pair smaller than lateral pair; specialized setae of first gastral tergite spatulate, full complement 4 pairs in two longitudinal rows.

Color orange brown.

Queen

Longino (2013) - HW 0.95–1.01, HL 0.88–0.91, SL 0.49–0.57, SLL 0.07–0.08, CI 109–113, SLI 14–15 (n=3). Similar to worker in most respects; ocelli present; compound eye much larger than worker eye; anepisternum separated from katepisternum by U-shaped groove; metapleuron separated from propodeum by broad U-shaped groove; pronotum coarsely rugose dorsolaterally, irregularly punctate to smooth and shining anteriorly and laterally; anepisternum longitudinally rugose dorsally, smooth and shining over most of surface; katepisternum smooth and shining; side of propodeum rugulose dorsally, smooth and shining to opalescent ventrally; mesoscutum punctatorugose; scutellum irregularly rugose; axilla separated from scutellum by broad transverse trough with coarse longitudinal rugae; pronotum with 1 pair spatulate setae; mesoscutum with 6 spatulate setae; axilla with spatulate seta; scutellum with 1 pair spatulate setae; first gastral tergite with number and arrangement of erect setae similar to worker.

Type Material

Longino (2013):

Syntype worker, queen, male: Honduras, Lombardia, San Juan Pueblo National Museum of Natural History, Museum of Comparative Zoology, Museu de Zoologia da Universidade de Sao Paulo (not examined).

Rhopalothrix reichenspergeri Syntype worker: Brazil, Santa Catarina: Blumenau Naturhistorisches Museum Basel (not examined).

References

  • Brown, W. L., Jr.; Kempf, W. W. 1960. A world revision of the ant tribe Basicerotini. Stud. Entomol. (n.s.) 3: 161-250 (page 211, Combination in Eurhopalothrix, and senior synonym of reichenspergeri and schmidti)
  • Longino J. T. 2013. A review of the Central American and Caribbean species of the ant genus Eurhopalothrix Brown and Kempf, 1961 (Hymenoptera, Formicidae), with a key to New World species. Zootaxa. 3693:101-151. doi:10.11646/zootaxa.3693.2.1
  • Mann, W. M. 1922. Ants from Honduras and Guatemala. Proc. U. S. Natl. Mus. 61: 1-54 (page 40, fig. 19 worker, queen, male described)
  • Wheeler, G. C.; Wheeler, J. 1955a [1954]. The ant larvae of the myrmicine tribes Basicerotini and Dacetini. Psyche (Camb.) 61: 111-145 (page 117, larva described)