Strumigenys thaxteri

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Strumigenys thaxteri
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. thaxteri
Binomial name
Strumigenys thaxteri
(Wheeler, W.M., 1916)

Strumigenys thaxteri casent0900194 p 1 high.jpg

Strumigenys thaxteri casent0900194 d 1 high.jpg

Specimen Labels

Known from a small number of specimens, collection data note one is from a forest and another from vegetation beating in an unspecified habitat. Field observations suggest it is a sit and wait ambush predator that captures insects that alight on the vegetation upon which they position themselves. Once prey is subdued they descend with it to ground level, where they presumably nest. Their massive mandibles, robust claws, dense body cover of long silky hairs, and sting may all contribute to detecting, trapping, and subduing larger sized, flying prey (Lattke et al., 2018).

Identification

Bolton (2000) - A member of the Strumigenys thaxteri-group. Known from Trinidad and Guyana, this very distinctive species is closely related only to Strumigenys reticeps, from which it is easily separated by the characters listed under the latter. S. thaxteri has extremely heavily built mandibles, bearing numerous relatively small teeth, that are reminiscent of those seen in the Malesian leptothrix-group, but even more massively developed. These heavy mandibles, coupled with reticulate-rugulose cephalic sculpture, dense pilosity, and the species-group characters listed above, render thaxteri easily identifiable.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Ecuador, Guyana, Trinidad and Tobago (type locality).


Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Castes

Nomenclature

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

  • thaxteri. Codiomyrmex thaxteri Wheeler, W.M. 1916d: 327, fig. 1 (w.) TRINIDAD. Combination in Pyramica: Bolton, 1999: 1672; in Strumigenys: Baroni Urbani & De Andrade, 2007: 129. See also: Brown, 1953g: 21; Bolton, 2000: 243.

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

Description

Worker

Bolton (2000) - TL 2.6-2.8, HL 0.64-0.68, HW 0.58-0.60, CI 88-90, ML 0.13-0.14, MI 19-22, SL 0.30-0.36, SI 55-60, PW 0.38-0.40, AL 0.70-0.72 (2 measured). Head in frontal view longer than broad; posterior cephalic margin laterally convex to straight, medially with shallow emargination framed by raised lamella; head widest posteriorly with broad concavity between posterolateral cephalic corner and frontal carina, cephalic lateral margins gradually converging anteriorly, each margin slightly sinuous; frontal carina projects laterally feebly as broad convexity. Frontal carina in cephalic dorsal view forms elongate surface with lateral margin higher than internal margin. Cephalic dorsum posteromedially markedly convex; most of cephalic surface rugose-reticulate except for clypeus and brief strip posteriorly of epistomal suture mostly smooth with scattered punctae. Clypeus longer than broad, posterior margin forms acute angle, margin broadly convex. Mandibles robust, mandibular lateral margin broadly convex, in lateral view mandibular median width is half its length. Mandibular dorsal surface smooth and shining, convex, with scattered piligeous punctulae, especially laterally; masticatory margin with series of 10–13 small interlocking teeth, apical tooth largest; ventral surface glabrous. Labrum slightly longer than broad in dorsal view (with mandibles open), wider basally than apicad, laterally broadly convex, apex bilobulate with fine incision. Width of labrum less than one-third that of clypeus in cephalic full-face view. Labrum in cross section at mid-length with convex dorsal margin and very concave ventral margin, in ventral view the lateral margin forms an elongate, column-like structure, apically bluntly rounded. Scattered fine hairs present along sides of labrum, apex with tuft of fine hairs shorter than half the basal labral width. Clypeal dorsum with appressed hairs directed meso-anteriorly; mandible with sparse fine, appressed hairs directed towards masticatory margin. In cephalic lateral view frontal carina extends posteriorly to posterolateral cephalic corner, lateral cephalic surface reticulose-punctate; eye protuberant, visible in cephalic frontal view, with 6–7 ommatidia across. Cephalic ventral surface posteriorly convex, coarsely rugose, distinct anteroventral tooth present close to mandibular insertion. Scape dorsal surface rugulose, ventral surface of scape mostly densely reticulate rugulose with smooth and shining elongate area that extends two-thirds along posterior margin of scape length, widest at apex and becoming progressively slender basally. Shining area light brown in contrast to surrounding darker sculpturing. Scapes do not reach posterior cephalic margin, in crosssection dorsal surface convex, ventral surface flat to concave. Mesosoma in lateral view with sinuous dorsal margin, promesonotum broadly convex, posteriorly broadly concave with minor irregularities on propodeum; lateral mesosomal surface mostly smooth and shining, pronotum with broad rugae, mostly transverse to oblique on dorsolateral surface and longitudinal along ventrolateral surface. Propodeal spine elongate and acute, extending posteriorly as low keel. Mesopleuron and anterior metapleuron mostly smooth, with very broad undulations, and shining, anepisternum with reduced, irregular undulations; mesopleuron with lamella along anteroventral margin. Posterior metapleuron with series of depressions and punctae, densest close to metapleural gland. Lateral propodeal face mostly rugulose, spiracle directed posterolaterally, separated from posterior propodeal margin by approximately one diameter. In dorsal view mesosoma widest anteriorly, anterolaterally strongly angular, posteriorly converging. Most of pronotal dorsum smooth and shining with scattered punctae, lateral margins with shallow rugosities; mesonotum strongly rugulose with median longitudinal crest, propodeal dorsum rugose to areolate. Dorsal and declivitous propodeal faces separated by transverse fine carina, declivity anteriorly reticulate-areolate, posteriorly smooth and shining. Lateral face of procoxa transversely striate on basal half up to two-thirds, apically rugulose. Dorsal surface of meso and metacoxae rugulose. Tibiae and femora mostly smooth and shining with scattered punctulae. Femora basally densely reticulate-areolate, extension of reticulate area increasing from profemur to metafemur. Petiolar node in lateral view with abrupt, weakly convex anterior margin, anterodorsal margin convex; postpetiolar margin evenly convex. Peduncle of petiole with flattened dorsal surface, abruptly dropping laterally; lateral surface with longitudinal carinae, swollen at spiracle; dorsal and lateral surface reticulate-areolate. Node of petiole rugose, postpetiolar dorsum rugulose with scattered longitudinal striae. Well-developed spongiform tissue present along length of petiolar ventrum, lateral margins of petiolar node, posterolateral margins of postpetiole, and lateral margins of abdominal sternite IV. Anteromedian region of abdominal sternite IV with thick tuft of hairs, resembling spongiform tissue. Basigastral costulae distinct, mostly along anterolateral margins, length under onefourth of surface of abdominal tergite IV. Gaster dorsum smooth and shining except for scattered punctulae. Abundant long and silky hairs cover most of dorsum of cephalic capsule and mesosoma (except for propodeal dorsum), petiolar node, postpetiole and gastral tergum. Legs, including tarsi, also with abundant long hairs, hairs shortest on protarsi. Protarsal claws shorter and relatively more slender than meso- and metatarsal claws. Hairs on cephalic dorsum longest posteriorly, ventral cephalic surface also with abundant hairs but all relatively shorter. Scape and funiculus with abundant decumbent to appressed hairs, none standing. Body mostly black, legs dark brown to brown.

Type Material

Bolton (2000) - Lectotype (Museum of Comparative Zoology) and paralectotype workers, TRINIDAD: near Port of Spain (R. Thaxter) (MCZ, National Museum of Natural History, The Natural History Museum) [examined].

References

  • Baroni Urbani, C. & De Andrade, M.L. 2007. The ant tribe Dacetini: limits and constituent genera, with descriptions of new species. Annali del Museo Civico di Storia Naturale “G. Doria” 99:1-191.
  • Bolton, B. 1999. Ant genera of the tribe Dacetonini (Hymenoptera: Formicidae). J. Nat. Hist. 3 33: 1639-1689 (page 1672, combination in Pyramica)
  • Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028. (page 243, fig. 163 redescription of worker)
  • Brown, W. L., Jr. 1953g. Revisionary studies in the ant tribe Dacetini. Am. Midl. Nat. 50: 1-137 (page 21, notes on worker)
  • Emery, C. 1924f [1922]. Hymenoptera. Fam. Formicidae. Subfam. Myrmicinae. [concl.]. Genera Insectorum 174C: 207-397 (page 325, Combination in Strumigenys, in catalogue)
  • Kempf, W. W. 1972b. Catálogo abreviado das formigas da regia~o Neotropical. Stud. Entomol. 15: 3-344 (page 77, catalogue)
  • Lattke, J.E., Da Silva, T.S.R., Delsinne, T. 2018. Taxonomy and natural history of Strumigenys thaxteri Wheeler and Strumigenys reticeps (Kempf) (Hymenoptera: Formicidae). Zootaxa 4438:137-147 (DOI 10.11646/zootaxa.4438.1.6).
  • Weber, N. A. 1934a. Notes on neotropical ants, including the descriptions of new forms. Rev. Entomol. (Rio J.) 4: 22-59 (page 52, revived combination)
  • Wheeler, W. M. 1916f. Ants collected in Trinidad by Professor Roland Thaxter, Mr. F. W. Urich, and others. Bull. Mus. Comp. Zool. 60: 323-330 (page 327, fig. 1 worker described)
  • Wheeler, W. M. 1922e. The ants of Trinidad. Am. Mus. Novit. 45: 1-16 (page 13, catalogue)