Strumigenys rusta

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

Pyramica rusta casent0102554 profile 1.jpg

Pyramica rusta casent0102554 dorsal 1.jpg

Specimen labels

Nothing is known about the biology of Strumigenys rusta.

Identification

Bolton (1983) - A member of the Strumigenys marginata-group. Related to Strumigenys marginata by the characters discussed in the species-group diagnosis, rusta is quickly separated from all other Afrotropical Smithistruma (Strumigenys) presently known by its combination of these characters with 6-segmented antennae.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: South Africa, Zimbabwe (type locality).


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

Nomenclature

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

  • rusta. Smithistruma rusta Bolton, 1983: 313, fig. 17 (w.) ZIMBABWE. Combination in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 127. See also: Bolton, 2000: 320.

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 2.0, HL 0.55, HW 0.37, CI 67, ML 0.07, MI 13, SL 0.27, SI 73, PW 0.24, AL 0.52.

Mandible with a principal dental row of 7 teeth of approximately the same size, followed distally by 4 minute denticles and a small apical tooth. Basal lamella of mandible concealed by clypeus. Anterior clypeal margin evenly broadly shallowly convex, the lateral margins more or less straight and parallel, not evenly convergent anteriorly throughout their length. Outer margins of closed mandibles in full-face view intersecting the anterior clypeal margin some distance in from the anterolateral angles, the outer mandibular margins and lateral clypeal margins not forming a more or less continuous line. Anterior and lateral clypeal margins without projecting hairs of any description, dorsum of clypeus without hairs. Dorsum of head behind clypeus with scattered simple fine hairs which are arched and decumbent, or appressed. Sides of head with long flagellate hairs present. Each member of the type-series has lost some flagellate hairs, which seem easily displaced by abrasion; the maximum number of flagellate cephalic hairs appears to be as follows. One pair posterolaterally on the occipital lobes which may be directed upwards or outwards; one pair directed laterally from the posteriormost point of the upper scrobe margins; one pair arising from the side of the head just above the last-mentioned pair and tending to be directed upwards rather than outwards; one pair more anteriorly situated on the upper scrobe margin, about on a level with the anterior margin of the eye. Pre ocular laminae in full-face view more or less parallel. Antennae with 6 segments, the scape narrow and not strongly flattened, bent approximately at its basal third. Leading edge of scape lacking a series of anteriorly projecting hairs, only with short decumbent to appressed fine pubescence. Maximum diameter of eye 0.11 X HW. Dorsum of clypeus closely punctulate, cephalic dorsum strongly reticulate-punctate everywhere except for a narrowly triangular smooth area running back from the posterior clypeal margin between the frontal lobes. Anterior border of pronotum sharply transversely marginate, the sides of the pronotum not marginate. Pronotal and mesonotal dorsa with a median longitudinal ridge or carina. Posterior half of mesonotum and all of propodeum narrowly marginate laterally. With alitrunk in profile the lateral mesonotal-propodeal margination continuous, without trace of a metanotal groove; however, mid-dorsally the median mesonotal ridge or carina ends at a distinct step-down at its junction with the propodeum. Propodeal teeth broadly triangular and with a conspicuous infradental lamella. Pronotal humeri each with a long fine flagellate hair. Dorsal alitrunk with 2-3 pairs of long fine curved hairs which are simple and erect, and with several pairs of decumbent to appressed fine simple short hairs. Dorsal surfaces of petiole and postpetiole with sparse but conspicuous erect to suberect fine hairs. Sides of alitrunk smooth and shining, with marginal feeble sculpture dorsal to and posterior to the extensive smooth area. Pronotal dorsum with 2-3 feeble longitudinal costulae on each side of the median ridge or carina, the spaces between the costulae filled with broad shallow superficial punctures. Mesonotum, propodeal dorsum, propodeal declivity between the teeth and petiole node densely punctate. Disc of postpetiole glassy smooth. First gastral tergite unsculptured except for the sparse widely spaced basigastral costulae. Spongiform appendages of pedicel segments strongly developed in profile. Petiole node in dorsal view with a narrow posterior lamina. Postpetiole in dorsal view with a narrow lamina on the anterior margin and with the lateral spongiform material visible projecting beyond the lateral margins of the disc. Posterior margin of postpetiole with a laminar rather than spongiform transverse strip; broadest laterally and narrowing medially where the posterior margin of the postpetiolar disc itself is indented. Base of first gastral tergite with a narrow laminar strip which is traversed by the sparse basigastral costulae. Colour glossy light brown.

Paratypes. TL 2.0-2.1, HL 0.5-0.58, HW 0.36-0.38, CI 63-69, ML 0.07-0.08, MI 12-14, SL 0.26-0.28, SI 70-78, PW 0.24-0.26, AL 0.52-0.56 (10 measured). As holotype.

Type Material

Holotype worker, Zimbabwe: Umtali, Melsetter, 1700 m, ii.1969 (R. Mussard) (Musee d'Histoire Naturelle Genève). Paratypes. 10 workers with same data as holotype (MHNG; The Natural History Museum; Museum of Comparative Zoology; Ecole Nationale Superieure Agronomique).

References