Strumigenys nigrescens

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Strumigenys nigrescens
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. nigrescens
Binomial name
Strumigenys nigrescens
Wheeler, W.M., 1911

Strumigenys nigrescens casent0281985 p 1 high.jpg

Strumigenys nigrescens casent0281985 d 1 high.jpg

Specimen Labels

Synonyms

Inhabits dry coastal forest, an unusual affinity for a Dacetine. Strumigenys nigrescens can also be found in many other habitats as well and its broad ecological tolerances are surely one reason this Strumigenys is relatively well collected from areas within its range.

Identification

Bolton (2000) - The unique dentition (see description below) is immediately diagnostic of nigrescens within the alberti-group., and will immediately separate smaller individuals of this species from Strumigenys furtiva.

Longino (Ants of Costa Rica) - Mandibles in side view straight, not broadly curved ventrally; mandibles relatively short, subtriangular, much of the apical portion meeting along a serially toothed masticatory margin when closed (former Smithistruma); leading edge of scape with a row of conspicuous projecting curved hairs, of which those distal to the subbasal bend distinctly curve toward the base of the scape; pronotal humeral hair present; ventral surface of petiole in profile with a deep, conspicuous and very obviously spongiform curtain, its maximum depth at least half that of the peduncle and usually more; disc of postpetiole completely unsculptured and glassy smooth; anterior border of clypeus broadly rounded; basal lamella of mandible immediately followed distally by the tooth-row, without a second lamella that extends forward for half the exposed length of the fully closed mandible; mandibles short, MI 19-24; eye with ten or more ommatidia in total; promesonotal dorsum with a fine median longitudinal carina through most or all of its length; pronotal dorsum partially to mostly sculptured; propodeal dorsum weakly to strongly reticulate-punctate; in full-face view anterior clypeal margin transverse to extremely shallowly convex between points where outer margins of fully closed mandibles intersect the clypeal margin; basal tooth-row of mandible consisting of alternating high narrow acutely triangular teeth and lower bluntly rounded broader teeth; tooth four from base particularly broad and rounded; disc of petiole node in dorsal view much broader than long, roughly transversely rectangular, the sides not converging anteriorly. Similar to Strumigenys fridericimuelleri and Strumigenys parsauga.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Belize, Costa Rica, Cuba, Dominican Republic, El Salvador, Greater Antilles, Guatemala, Haiti, Honduras, Jamaica (type locality), Lesser Antilles, Mexico, Nicaragua, Trinidad and Tobago.


Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Nesting site from the Dominican Republic. The ants were found in the rotting wood and litter in the bottom of the hollow of this log.

This species has been found in dry coastal forests and the beach in Costa Rica (Longino, Ants of Costa Rica), and I found a colony in sea grape litter on Long Island, Bahama (Deyrup 1997).

Brown (1953) - A very common ant in Cuba, occurring in all sort of habitats. It is known from one end of the island to the other in agricultural as well as wilder districts. Many of the reported colonies were found nesting under stones. (Brown 1953).

Longino (Ants of Costa Rica) - Occurs in coastal areas, dry forest, and disturbed habitats. My collections are from Winkler samples of sifted leaf litter. Its geographic distribution and habitat preference suggest it could be a tramp species dispersed by commerce.

Castes

Nomenclature

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

  • nigrescens. Strumigenys alberti var. nigrescens Wheeler, W.M. 1911a: 28 (w.) JAMAICA. Brown, 1953g: 98 (q.); Wheeler, G.C. & Wheeler, J. 1955a: 143 (l.). Combination in S. (Cephaloxys): Emery, 1924d: 325; in Smithistruma: Brown, 1953g: 96; in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 125. Raised to species and senior synonym of longipilis, nana: Brown, 1953g: 96. See also: Bolton, 2000: 157.
  • nana. Strumigenys (Cephaloxys) alberti var. nana Santschi, 1930e: 80 (w.) CUBA. Junior synonym of nigrescens: Brown, 1953g: 97.
  • longipilis. Strumigenys (Cephaloxys) alberti subsp. longipilis Weber, 1934a: 50 (w.) CUBA. Combination in Smithistruma: Brown, 1948e: 106. Junior synonym of nigrescens: Brown, 1953g: 97.

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 1.8 - 2.0, HL 0.46 - 0.52, HW 0.36 - 0.42, CI 71 - 76, ML 0. 10 - 0.12, MI 21 - 24, SL 0.23 - 0.25, SI 60 - 65, PW 0.22 - 0.26, AL 0.42 - 0.52 (10 measured). Masticatory margin of mandible with characteristic dentition: basal lamella is followed by a small blunt first (basal) tooth; teeth 2, 4, and 6 are low, broad and broadly rounded apically; teeth 3, 5 and 7 are taller and narrower, triangular and acute. No secondary lamella present immediately distal of the basal lamella. Anterior clypeal margin broadly and very shallowly convex between the points where the outer margins of the closed mandibles intersect the clypeal margin, sometimes almost transverse. Apicoscrobal hair flagellate, long and fine, sometimes looped. Eye with 4 - 5 ommatidia in the longest row. Promesonotum with a variably developed median longitudinal carina. At maximum the carina distinct through entire length of pronotum and most of mesonotum; at minimum conspicuous only posteriorly on pronotum and anteriorly on mesonotum. Pronotum dorsally usually completely sculptured with fine costulae, punctation, or both. Occasionally the sculpture weak or even partially effaced anteromedially. Petiole node in dorsal view distinctly broader than long.

Queen

Brown (1953) - TL 2.27, HL 0.5 1 , WL 0.58, CI 80, MI 24, forewing Lca. 1 .8 mm. Differs from the worker in the usual ways. Erect feebly spatulate hairs of the head present in the normal Strumigenys pattern, with a pair straddling the ocellar triangle and a transverse row of four on the posterior occiput. Flagelliform hairs as in the worker, similarly placed. Scutum feebly longitudinally rugulose in the center, with a median carinula; scutal hairs subflagellate, curved posteriorly. Color bright ferrugineous; ocellar triangle deeply infuscated.

Type Material

Bolton (2000):

Holotype worker, JAMAICA: Mandeville (A.G. Wight) (American Museum of Natural History) [examined].

Strumigenys (Cephaloxys) alberti var. nana Santschi, 1930: 80. Holotype worker, CUBA: Havana (A. Bierig) (Naturhistorisches Museum, Basel) [not seen].

Strumigenys (Cephaloxys) alberti subsp. longipilis Weber, 1934a: 50. Holotype worker, CUBA: Cayamas, 6.3 (E.A. Schwarz). (Museum of Comparative Zoology) [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). Journal of Natural History. 33:1639-1689. PDF (page 1673, Combination in Pyramica)
  • Bolton, B. 2000. The ant tribe Dacetini. Mem. Am. Entomol. Inst. 65: 1-1028 (page 157, fig. 121 redescription of worker)
  • Brown, W. L., Jr. 1953. Revisionary studies in the ant tribe Dacetini. American Midland Naturalist. 50:1-137. PDF (page 98, queen described; page 96, Combination in Smithistruma, raised to species, and senior synnonym of longipilis and nana)
  • Deyrup, M. 1997. Dacetine ants of the Bahamas (Hymenoptera: Formicidae). Bahamas J. Sci. 5:2-6.
  • Emery, C. 1924f [1922]. Hymenoptera. Fam. Formicidae. Subfam. Myrmicinae. [concl.]. Genera Insectorum 174C: 207-397 (page 325, Combination in S. (Cephaloxys))
  • Wheeler, G. C.; Wheeler, J. 1955a [1954]. The ant larvae of the myrmicine tribes Basicerotini and Dacetini. Psyche (Camb.) 61: 111-145 (page 143, larva described)
  • Wheeler, W. M. 1911a. Additions to the ant-fauna of Jamaica. Bull. Am. Mus. Nat. Hist. 30: 21-29 (page 28, worker described)