Strumigenys hensekta

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Strumigenys hensekta
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. hensekta
Binomial name
Strumigenys hensekta
(Bolton, 1983)

Pyramica hensekta casent0102546 profile 1.jpg

Pyramica hensekta casent0102546 dorsal 1.jpg

Specimen labels

Known from litter samples from a range of wet forest habitats.

Identification

Bolton (2000) - The only member of the hensekta complex in the Strumigenys emarginata group.Characters of hensekta-complex. Anterior clypeal margin transverse. Maximum diameter of eye less than maximum width of scape. Base of first gastral tergite without an indented depressed median area. First gastral tergite in dorsal view with suture line between limbus and sclerite proper transverse. Dorsum of head with numerous standing simple hairs from about highest point of vertex to occipital margin. Pronotal humerus with a laterally projecting stout hair. Dorsal alitrunk with standing hairs on both pronotum and mesonotum, and first gastral tergite with numerous standing hairs. Pleurae and side of propodeum mostly or entirely reticulate-punctate.

Bolton (1983) - Apart from slight variation in intensity of punctate sculpture on the alitrunk the main variation is only that 6-7 pairs of hairs may be present on the dorsal alitrunk and that the outermost pair of hairs on the anterior clypeal margin (at the corners) may be relatively small, so that the anterior margin may have 3-4 medially curved pairs of hairs.

Within the emarginata-group hensekta is quickly diagnosed by its transverse anterior clypeal margin and characteristic pilosity as described above. It apppears closest related to Strumigenys truncatidens but the two are separated as follows in the worker.

hensekta truncatidens
HW 0.37-0.41, CI 66-69. HW 0.46-0.54, CI 72-76.
Anterior clypeal margin transverse. Anterior clypeal margin concave.
Dorsum of head from highest point of vertex to occiput with erect to suberect simple to clavate hairs. Dorsum of head from highest point of vertex to occiput with anteriorly curved flattened hairs which are suberect only close to occipital margin.
Pronotal humeri each with a laterally projecting stout feebly clavate hair. Pronotal humeri without laterally projecting hairs.
Dorsal alitrunk with 6-7 pairs of stout erect hairs. Dorsal alitrunk with 1-2 pairs of stout erect hairs.
Base of first gastral tergite with a broad spongiform strip, the basigastral costulae not traversing it, not running up to the basal margin. Base of first gastral tergite without a broad spongiform strip, the basigastral costulae running up to the basal margin.
Posterior spongiform appendage of postpetiole not interrupted medially. Posterior spongiform appendage of postpetiole interrupted medially.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Angola, Cameroun, Democratic Republic of Congo, Gabon, Ghana (type locality), Ivory Coast, 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

Worker

Nomenclature

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

  • hensekta. Smithistruma hensekta Bolton, 1983: 293, fig. 12 (w.) GHANA. Combination in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 121. See also: Bolton, 2000: 303.

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 0.60, HW 0.41, CI 68, ML 0.10, MI 17, SL 0.24, SI 59, PW 0.25, AL 0.58.

Mandibles with 5 relatively large teeth following the basal lamella (concealed by the clypeus), distal to which are 2 slightly smaller teeth followed by 4 minute denticles and a small apical tooth. Anterior clypeal margin transverse, equipped with 3 pairs of medially curved flattened hairs of which the outermost pair is the largest, forming a transition to the long anteriorly curved spatulate hairs which form a continuous fringe along the lateral clypeal margins. Sides of clypeus feebly convergent anteriorly. With the head in full-face view the sides with numerous straight to slightly curved freely projecting stout hairs which are feebly clavate. Dorsum of clypeus and cephalic dorsum from posterior clypeal margin to highest point of vertex with numerous short scale-like hairs which are curved anteriorly. Scale-like hairs absent from highest point of vertex back to the occipital margin, replaced by numerous distinctly longer erect to suberect hairs which are simple to feebly clavate and mostly slightly curved anteriorly. This broad band of simple hairs occupies the dorsum from the vertex to the occiput and the surfaces of the occipital lobes. Flagellate hairs absent. Antennal scapes curved and broadened at about the basal third, the leading edge of the scape with a freely projecting row of long stout hairs. Maximum diameter of eye 0·15 x HW. Cephalic dorsum reticulatepunctate everywhere, with a rough granular appearance. Clypeal dorsum less strongly sculptured than remainder of head. Pronotum not sharply marginate laterally, lacking a median longitudinal ridge or carina dorsally and without flagellate hairs at the humeri. Metanotal groove absent but posterior half of mesonotum very shallowly concave. Propodeal teeth long and narrow, slightly upcurved along their length. Infradental lamellae vestigial. Flagellate hairs absent but pronotal humeri each with a laterally projecting stout hair which is feebly clavate. Dorsal alitrunk with 6 pairs of elongate stout erect hairs which are simple to feebly clavate, and similar hairs are numerous on the petiole, postpetiole and first gastral tergite but tending to be curved posteriorly on the pedicel segments; without other pilosity. Sides of alitrunk densely punctate. Dorsal alitrunk densely punctate, the punctures slightly smaller and more widely spaced on the pronotum than on the mesonotum or propodeum. Dorsum of petiole finely punctate; disc of postpetiole unsculptured and glassy smooth. First gastral tergite unsculptured except for the sharply defined row of basigastral costulae. Spongiform appendages of pedicel segments strongly developed in profile. In dorsal view the petiole node with a spongiform strip along the posterior margin, the spongiform material also extending down the posterolateral surfaces of the node. Anterior postpetiolar margin transverse to exceptionally feebly concave, with a narrow spongiform strip; the posterior margin with a much broader spongiform band which is broadest posterolaterally and narrowed medially. In dorsal view the lateral spongiform tissue of the post petiole can be seen projecting beyond the outline of the disc. Base of first gastral tergite with a transverse spongiform band which is overlapped by that on the posterior margin of the postpetiole. Colour uniform dull yellow.

Paratypes. TL 2.0-2.1, HL 0.58-0.60, HW 0.39-0.41, CI 67-68, ML 0.10-0.11, MI 17-18, SL 0.24-0.25, SI 59-63, PW 0.24-0·26, AL 0.58-0.60 (4 measured).

As holotype but in two workers the mandibles are open and the basal lamella is visible as a broad-based high triangle which tapers strongly to a narrow truncated apex; there is no diastema between the basal lamella and the basalmost tooth of the principal row.

Bolton (2000) - TL 2.0-2.2, HL 0.56-0.60, HW 0.37-0.41, CI 66-69, ML 0.10-0.12, MI 17-18, SL 0.24-0.25, SI 59-65, PW 0.24-0.26, AL 0.58-0.61 (15 measured).

Type Material

Holotype worker, Ghana: Mampong, 9.ii.I970 (P. Room) (The Natural History Museum). Paratypes. 4 workers with same data as holotype (BMNH; Musee National d'Histoire Naturelle; Museum of Comparative Zoology).

References