Strumigenys cavinasis

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Strumigenys cavinasis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. cavinasis
Binomial name
Strumigenys cavinasis
(Brown, 1950)

Pyramica cavinasis casent0178306 profile 1.jpg

Pyramica cavinasis casent0178306 dorsal 1.jpg

Specimen labels

A few dozen records show this species inhabits a range of wet forest habitats. It is typically collected in litter samples.

Identification

Bolton (1983) - A member of the chyatha complex in the Strumigenys emarginata group. One of only two species in the emarginata-group to show broadly scale-like to suborbicular hairs all over the head, cavinasis shares this character with sharra. Workers of the two species are separated as follows.

cavinasis sharra
Head absolutely and relatively shorter, HL 0.52-0.56, CI 63-67. Head absolutely and relatively longer, HL 0.58-0.64, CI 56-63.
Antennal scapes absolutely and relatively shorter, SL 0.22-0.26, SI 63-70. Antennal scapes absolutely and relatively longer, SL 0·26-0.28, SI 73-78.
Posterior margin of postpetiole disc without a row of spatulate to squamate hairs on each side of the midline. Posterior margin of postpetiolar disc with now of 5-6 spatulate to squamate hairs on each side of the midline which project backward over the spongiform strip.
Simple elongate hairs present on the postpetiolar disc. Simple elongate hairs absent from the postpetiolar disc.
Simple elongate hairs present on the basal portion of the first gastral tergite. Simple elongate hairs absent from the basal portion of the first gastral tergite.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Angola, Cameroun, Democratic Republic of Congo (type locality), Gabon, Ghana, Kenya, Uganda.


Distribution based on AntMaps

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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

Queen

Nomenclature

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

  • cavinasis. Smithistruma (Smithistruma) cavinasis Brown, 1950b: 42 (w.) DEMOCRATIC REPUBLIC OF CONGO. Combination in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 117. See also: Brown, 1953g: 129; Bolton, 1983: 287; Bolton, 2000: 300.

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

Description

Worker

Bolton (1983) - TL 1.9-2.1, HO 0.52-0.56, HW 0.34-0.37, CI 63-67, ML 0.04-0.06, MI 7-10, SL 0.22-0.26, SI 63-70, PW 0.23-0.25, AL 0.50-0.56 (10 measured).

Mandibular dentition of 5 large teeth following the basal lamella without a diastema, then two slightly smaller teeth and a series of 4 small denticles before the apical tooth. Anterior clypeal margin broadly deeply and evenly concave, the concavity including the whole of the anterior margin except for the anterolateral corners. Lateral margins of clypeus convergent anteriorly and fringed with a continuous row of large flattened spatulate to roughly spoon-shaped projecting hairs which are curved anteriorly. Anterior clypeal margin with a row of 6 broadly scale-like to suborbicular hairs which project out over the mandibles. Dorsum of clypeus and of head with numerous broadly scale-like to suborbicular hairs, densest on the clypeus; such hairs also fringing the lateral borders of the head in full-face view. Flagellate hairs or other pilosity absent. Pre ocular laminae broad in full-face view and somewhat divergent anteriorly. Antennal scapes narrow basally, bent at about the basal quarter and suddenly broadened, broadest at about this level and the leading edge bluntly subangulate. Dorsal surface of scape with scale-like hairs but leading edge with a series of freely projecting longer narrower hairs, the longest of which occurs at the angle. Eyes of moderate size, 0.11-0.14 X HW, the diameter less than the maximum width of the scape. Dorsum of head finely and densely reticulate-punctate, with a granular appearance. Dorsal alitrunk with scattered but conspicuous scale-like to suborbicular hairs, smaller versions of which also occur on the petiole dorsum but which are sparse or absent from the postpetiolar disc and absent from the gaster. Elongate simple hairs absent from alitrunk but present on the petiole (1 pair), postpetiole (2-3 pairs) and base of the first gastral tergite (usually 1-2 pairs but sometimes 3 pairs). Flagellate hairs absent. Alitrunk not marginate laterally, the pronotum without a median longitudinal ridge or carina dorsally. With the alitrunk in profile the mesonotum very slightly raised above the level of the pronotum and propodeum. Metanotal groove not impressed but its site marked by a small step-down from the mesonotal to the propodeal dorsum. Propodeal teeth strong and broad basally, the infradental lamellae very narrow and with a distinctly concave outline. Mesopleuron reticulate-punctate, the remainder of the sides of the alitrunk unsculptured or only with faint superficial sculpture. Pronotal dorsum finely superficially longitudinally striolate to feebly rugulose, the remainder of the dorsum and the petiole dorsum punctulate. Disc of postpetiole smooth and first gastral tergite unsculptured except for the basigastral costulae. Spongiform appendages massively developed in profile. In dorsal view the sides and posterior margin of the petiole node surrounded by continuous thick spongiform material. The postpetiole with an anterior spongiform transverse strip and with the lateral spongiform material projecting beyond the sides of the disc in dorsal view. Posterior margin of postpetiole disc with a continuous broad spongiform strip which is slightly narrower centrally than at the sides. Base of first gastral tergite with a transverse spongiform band as wide as that on the posterior margin of the postpetiole, and like the postpetiolar strip this is also broadest at the sides and narrow centrally. Colour medium to light brown.

Type Material

Bolton (1983) - Holotype worker, ZAIRE: Ituri Forest between Beni and Irumu, ii.1948, no. 2129 (N. A. Weber) (American Museum of Natural History) [examined].

References