Strumigenys ravidura

Every Ant Tells a Story - And Their Stories Are Here
Jump to navigation Jump to search
Strumigenys ravidura
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. ravidura
Binomial name
Strumigenys ravidura
(Bolton, 1983)

Strumigenys ravidura casent0900054 p 1 high.jpg

Strumigenys ravidura casent0900054 d 1 high.jpg

Specimen Labels

One of the small number of collections of this species was noted as being from a rainforest litter-sample.

Identification

Bolton (2000) - A member of the Strumigenys thuvida-group. S. ravidura separates from its close relative Strumigenys belial by having the clypeal dorsum distinctly concave, and from Strumigenys nimravida by lacking standing hairs anywhere on the head, alitrunk and gaster.

Bolton (1983) - The combination of characters noted in the species-group diagnosis quickly separates ravidurus from all its Afrotropical congeners. The scale-like hairs on the head and body are very conspicuous and at first sight are the most obvious feature of this species. Only one other African species in the genus is similarly covered with scale-like hairs, Strumigenys tukulta, although several have appressed scale-like hairs on the clypeal dorsum alone.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Cameroun (type locality), Gabon.

Distribution based on AntMaps

AntMapLegend.png

Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Strumigenys were once thought to be rare. The development and increased use of litter sampling methods has led to the discovery of a tremendous diversity of species. Many species are specialized predators (e.g. see Strumigenys membranifera and Strumigenys louisianae). Collembola (springtails) and other tiny soil arthropods are typically favored prey. Species with long linear mandibles employ trap-jaws to sieze their stalked prey (see Dacetine trap-jaws). Larvae feed directly on insect prey brought to them by workers. Trophallaxis is rarely practiced. Most species live in the soil, leaf litter, decaying wood or opportunistically move into inhabitable cavities on or under the soil. Colonies are small, typically less than 100 individuals but in some species many hundreds. Moist warm habitats and micro-habitats are preferred. A few better known tramp and otherwise widely ranging species tolerate drier conditions. Foraging is often in the leaf litter and humus. Workers of many species rarely venture above ground or into exposed, open areas. Individuals are typically small, slow moving and cryptic in coloration. When disturbed individuals freeze and remain motionless. Males are not known for a large majority of species.

Castes

Nomenclature

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

  • ravidura. Glamyromyrmex ravidurus Bolton, 1983: 331, fig. 28 (w.) CAMEROUN. Combination in Pyramica: Bolton, 1999: 1672; in Strumigenys: Baroni Urbani & De Andrade, 2007: 126. See also: Bolton, 2000: 332.

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

Description

Worker

Holotype. TL 2.1, HL 0.54, HW 0.41, CI 76, ML 0.11, MI 20, SL 0.22, SI 54, PW 0.24, AL 0.58.

Mandible with 11 teeth following the basal lamella without a diastema, the dentition consisting of a basal series of 6 relatively large teeth followed distally by 2 slightly smaller teeth and an apical series of three denticles which share a common base (from a paratype with open mandibles). Masticatory margin obscured in dorsal view by the numerous scale-like hairs arising from the blade which project medially over the teeth. In profile the mandibles strongly arched-downcurved, the upper margin strongly curved and its highest point above the level of the anterior clypeal margin. Median portion of clypeal dorsum depressed and more or less flat, the lateral margins weakly elevated. Anterior clypeal margin very feebly indented medially, almost transverse, the lateral portions of the anterior margin slightly elevated. In full-face view the sides of the head behind the level of the antennal insertions evenly divergent to the apices of the scrobes then passing through an obtuse angle and gradually converging occipitally. Rounded posteriorly projecting occipital lobes present. Mandibles, clypeus, entire cephalic dorsum and antennal segments all with numerous conspicuous appressed scale-like hairs, without other pilosity of any description. Lateral margins of head without flagellate hairs. With head in profile the eyes very small, with only 4-5 ommatidia. Scale-like hairs present on the sides of the head behind the deep scrobes and on the pre ocular laminae and the lateral portion of the clypeus in front of the antennal insertions. Clypeus superficially and very faintly reticulate, the cephalic dorsum weakly reticulate-granular between the scale-like hairs. Antennal scapes weakly clavate in full-face view, broadest close to the midlength and their leading edges equipped with a series of appressed scale-like hairs which lie almost nose-to-tail, the apex of one hair nearly touching the base of the next. Pronotum marginate anteriorly but not marginate laterally. Mesonotum not marginate but the short propodeum laterally angulate between sides and dorsum; the dorsum broader than long. Metanotal groove not impressed but present across the dorsal alitrunk as a narrow transverse line. In profile the dorsal alitrunk outline more or less evenly convex, highest at about the mesonotal midlength. Propodeal teeth short, upcurved at the extreme apex, confluent ventrally with the broad infradental lamellae, the latter with their free margins more or less vertical, not evenly concave. Sides of alitrunk unsculptured, with scattered scale-like hairs on sides of pronotum. Dorsum of promesonotum with superficial faint reticular patterning and scattered appressed scale-like hairs which are similar to those on the head but narrower and in general more widely spaced. Propodeal dorsum smooth and without scale-like hairs. Flagellate hairs absent from alitrunk, without pilosity of any description other than the scale-like hairs. Pedicel segments in profile with spongiform appendages enormously developed. Petiole with ventral appendage forming a deep narrow lobe anteriorly but in its posterior half the spongiform tissue is much expanded laterally so that it is clearly visible in dorsal view. Ventral spongiform appendage of postpetiole massive and base of first gastral sternite with a well-developed spongiform pad. Petiole node in dorsal view approximately as broad as long, with a broad lamellate posterior strip. Disc of postpetiole surrounded on all sides by lamellar or spongiform material, the disc broadest in front of the midlength, the sides convergent posteriorly and the posterior margin not indented medially. Base of first gastral tergite with a lamellate spongiform strip which is traversed by the basigastral costulae, the latter very short and scarcely extending onto the tergite proper. Petiole, postpetiole and gaster unsculptured, the only pilosity present on all these surfaces being appressed scale-like hairs. Posterior margins of petiole and postpetiole with a series of large scale-like hairs which overlap the lamellar strips, these hairs much larger than those on the dorsal surfaces of the petiole and postpetiole. Colour dark brown.

Paratype. TL 2.1, HL 0.56, HW 0.43, CI 77, ML 0.12, MI 21, SL 0.22, SI 51, PW 0.25, AL 0.60. As holotype.

Bolton (2000) - TL 2.0-2.1, HL 0.52-0.56, HW 0.40-0.43, CI 75-80, ML 0.11-0.13, MI 20-24, SL 0.22-0.23 , SI 51-55, PW 0.24-0.25, AL 0.54-0.60 (8 measured).

Type Material

Holotype worker, Cameroun: nr Yaounde, sample SQ (G. Terron) (Ecole Nationale Superieure Agronomique).

Paratypes. 1 worker, nr Yaounde, sample SV (G. Terron); 1 worker, nr Yaounde, sample YM (G. Terron) (The Natural History Museum; ENSA).

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. 1983. The Afrotropical dacetine ants (Formicidae). Bull. Br. Mus. (Nat. Hist.) Entomol. 46:267-416. PDF (page 331, fig. 28 worker described)
  • 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 332, figs. 216, 238 redescription of worker)