Nesomyrmex denticulatus

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Nesomyrmex denticulatus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Nesomyrmex
Species group: angulatus
Species: N. denticulatus
Binomial name
Nesomyrmex denticulatus
(Mayr, 1901)

Nesomyrmex denticulatus casent0906197 p 1 high.jpg

Nesomyrmex denticulatus casent0906197 d 1 high.jpg

Specimen Labels

Mbanyana and Robertson (2008) - Usually nests in cavities of branches on trees and bushes that were previously excavated by wood-boring beetles or termites. Nests have also been found in cavities at the base of old Protea inflorences that were previously excavated by beetle or lepidopteran larvae. It is found in vegetation of the Western Cape and Eastern Cape that has a woody component, including late succession Fynbos, Succulent Karoo that has large bushes, Southern Afrotemperate Forest (mainly along edges) and possibly also Albany Thicket.

Identification

A member of the angulatus species-group.

Hita Garcia et al. (2017) - The following character combination separates N. denticulatus from the remainder of the group: eyes with 10–12 ommatidia in longest row; in profile mesosomal dorsum with conspicuously impressed metanotal groove; in dorsal view petiolar node laterally denticulate; subpetiolar process with a conspicuous tooth anteriorly followed by a long cuticular flange which runs back to the postpetiolar junction; dorsum of propodeum with standing hairs; first gastral tergite with standing hairs evenly distributed throughout.

The three species, N. denticulatus, Nesomyrmex innocens and Nesomyrmex stramineus, are morphologically very similar and can be well separated from the other species by the laterally denticulate petiolar node. The separation of these three can be challenging though. Nesomyrmex denticulatus is larger in general body size, has larger eyes with more ommatidia, and a subpetiolar process with a conspicuous tooth anteriorly, followed by a long cuticular flange which runs back to the postpetiolar junction, and slightly denser pilosity.

Bolton (1982) - Among the species in which the metanotal groove is impressed three, denticulatus, Nesomyrmex innocens, and Nesomyrmex stramineus, have the petiole node bearing denticles from which hairs arise. Of the three denticulatus is recognized by its strongly developed subpetiolar process, dense pilosity, larger eyes and larger size.

Keys including this Species

Distribution

Hita Garcia et al. (2017) - Nesomyrmex denticulatus is only known from South Africa, where it seems to be relatively common in the Western and Eastern Cape regions.

Distribution based on Regional Taxon Lists

Afrotropical Region: South Africa (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Castes

Nomenclature

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

  • denticulatus. Leptothorax denticulatus Mayr, 1901b: 5 (w.q.) SOUTH AFRICA. Combination in L. (Goniothorax): Wheeler, W.M. 1922a: 891; in Nesomyrmex: Bolton, 2003: 272. See also: Bolton, 1982: 328; Mbanyana & Robertson, 2008: 38.

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

Description

Worker

Bolton (1982) - TL 3.1-3.5, HL 0.74-0.84, HW 0.62-0.68, CI 81-85, SL 0.46-0.48, SI 71-74, PW 0.46-0.52, AL 0.82-0.94 (8 measured).

Mandibles finely shagreened to virtually smooth. Anterior margin of median lobe of clypeus evenly arched-convex; median clypeal carina present and usually quite distinct. Frontal carinae absent; antennal scrobes absent. Maximum diameter of eye 0.16-0.19, about 0.26-0.29 x HW and with 10-11 ommatidia in the longest row; the eye in profile only very slightly longer than high. With the head in full-face view the occipital margin straight to feebly convex, rounding evenly into the sides; the latter slightly narrower in front of the eyes than behind and feebly convergent anteriorly. With the alitrunk in profile the promesonotum shallowly convex dorsally, the metanotal groove impressed and the propodeal dorsum convex. Propodeum armed with a pair of strong spines which are longer than their basal width. Metapleural lobes rounded. In dorsal view the alitrunk with the pronotal corners bluntly angular to narrowly rounded. Petiole node in profile large and blocky, the upper sides and dorsum with numerous peaks or denticles from which hairs arise. Peduncle of petiole short and broad, subtended by an extensive ventral process which takes the form of a triangular denticle or tooth anteriorly, followed by a long cuticular ridge which runs back to the junction with the postpetiole. In ventral view the subpetiolar ridge is seen to fork at about its midlength, forming an inverted Y-shape. With the pedicel segments in dorsal view the denticles conspicuous on the sides of both the petiole and postpetiole; both segments broader than long, the latter somewhat broader than the former. Dorsum of head covered with a blanket of fine dense punctulate ground-sculpture which is overlaid everywhere by dense and very fine rugular sculpture. On the dorsum the rugulae are close and longitudinal but on the sides, above the eyes and occipitally there is a tendency for a narrow reticulum to be formed. Dorsal alitrunk reticulate-punctate and with fine rugulae which are predominantly longitudinal; on the promesonotum a reticulum may be formed anteriorly and in some the rugulae are quite strongly developed. Sculpture of petiole and postpetiole dorsally predominantly reticulate-punctate but a few fine rugulae may be present. Base of first gastral tergite superficially reticulate to almost smooth. All dorsal surfaces of head and body densely and evenly clothed with short blunt hairs; the appendages without such hairs. Colour uniform yellow, sometimes the posterior half of the gaster darker than the anterior half.

Mbanyana and Robertson (2008) - HL 0.828–0.921, HW 0.629–0.757, HW1 0.679–0.795, CI 73–84, SL 0.462–0.580, SI 73–77, PW 0.482–0.590, ML 0.895–1.087, EL 0.177–0.216, EI 26–29 (5 of 61 measured).

Description as in Bolton (1982), but with the following differences: mandibles are described as finely shagreened to virtually smooth but in the material that we observed mandibles can also have fine longitudinal striations.

References