Stenamma sardoum

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Stenamma sardoum
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Stenammini
Genus: Stenamma
Species: S. sardoum
Binomial name
Stenamma sardoum
Emery, 1915

Stenamma sardoum casent0904150 p 1 high.jpg

Stenamma sardoum casent0904150 d 1 high.jpg

Specimen Labels

Seemingly this is a Sardinian endemic, but maybe it occurs also in Corsica (Rigato & Toni, 2011).

Identification

Rigato (2011) - This species has no unique strong diagnostic features, but, besides its distribution, it is recognisable by the following combination of worker characters: the values of SI (usually ≥ 90) and PCI (range: 25–34) plus relatively low and elongate postpetiole and irregular promesonotal sculpturation. The gyne is similar, except for the sculpturation.

At a glance sardoum female castes were easily separated from co-occurring specimens of debile because females of sardoum are mostly ferrugineous, distinctly paler than the brown debile, even though colour differences are generally considered unreliable. Also, in sardoum petiolar and postpetiolar sternites in profile look distinctly, although weakly, more concave below the nodes. In contrast, the waist sternites of Stenamma debile are only faintly concave at most. This difference is easier to appreciate when specimens of both species are compared directly. Stenamma sardoum female castes generally look similar to Stenamma westwoodii. Diagnostic features useful to separate them are difficult to appreciate and rely on difference in PCI, promesonotal sculpturation and shape of postpetiole.

Keys including this Species

Distribution

Seemingly a relatively common Sardinian endemic. (Rigato 2011)

Distribution based on Regional Taxon Lists

Palaearctic Region: Italy (type locality), Malta.


Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Castes

Worker

Queen

Nomenclature

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

  • sardoum. Stenamma sardoum Emery, 1915a: 255, pl. 4, figs. 5, 6 (w.q.) ITALY (Sardinia). See also: DuBois, 1998b: 237; Rigato, 2011: 11.

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

Emery (1915) described Stenamma sardoum on the basis of a few workers and one gyne, comparing it with Stenamma westwoodii of earlier authors (i.e. specimens now known to be Stenamma debile) and pointed out the strong difference in the shape of the petiolar node that he described as truncate in profile. Actually, Emery was quite wrong in reporting such a feature, even adding a misleading figure. I examined the type series and several other specimens of S. sardoum and all of them have an ordinary, somewhat rounded node in profile with a faint flattening at most. DuBois (1998) designated the lectotype and redescribed S. sardoum. In his keys he stated that the petiolar node was “depressed”. Nevertheless his drawings showed a petiolar profile comparable to that of most Stenamma.

Description

Worker

Rigato (2011) - Lectotype (designated by DuBois (1998)): TL 3.6; HL 0.87; HW 0.72; CI 83; SL 0.66; SI 92; PnW 0.48; AL 1.00; PeL 0.38; PPL 0.26; PeH 0.20; PPH 0.21; PeW 0.16; PPW 0.21; PI1 68; PI2 53; MTL 0.61; TI 85.

Paralectotype: TL 3.6–3.9; HL 0.86–0.91; HW 0.72–0.77; CI 84–85; SL 0.67–0.70; SI 89–93; PnW 0.48–0.51; AL 1.04–1.10; PeL 0.38–0.42; PPL 0.26–0.29; PeH 0.20–0.23; PPH 0.21–0.23; PeW 0.15–0.18; PPW 0.20–0.23; PI1 68–69; PI2 53–55; MTL 0.61–0.65; TI 84–86 (3 measured).

TL 3.3–4.3; HL 0.81–0.91; HW 0.67–0.76; CI 82–85; SL 0.63–0.70; SI 89–96; PCI 25–34; PnW 0.43–0.51; AL 0.95–1.11; PSI 1.58–1.88; PeL 0.37–0.42; PPL 0.23–0.27; PeH 0.19–0.22; PPH 0.18–0.22; PeW 0.15–0.17; PPW 0.19–0.23; PI1 62–69; PI2 51–57; MTL 0.56–0.65; TI 81–89 (17 measured).

Queen

Rigato (2011) - Paralectotype: TL 4.5; HL 0.95; HW 0.82; CI 86; SL 0.74; SI 90; ScW 0.64; MnL 1.01; PeL 0.48; PPL 0.33; PeH 0.25; PPH 0.26; PeW 0.20; PPW 0.28; PI1 69; PI2 59; MTL 0.72; TI 88.

TL 4.4–5.0; HL 0.92–1.01; HW 0.79–0.85; CI 84–86; SL 0.71–0.76; SI 89–90; PCI 30–34; AL 1.28–1.40; PSI 1.60–2.10; ScW 0.64–0.68; MnL 0.92–1.01; PeL 0.47–0.50; PPL 0.31–0.33; PeH 0.25; PPH 0.24–0.26; PeW 0.20–0.21; PPW 0.26–0.28; PI1 66; PI2 59; MTL 0.66–0.73; TI 84–86 (2 measured).

Type Material

Rigato (2011) - Lectotype worker, paralectotype workers and gyne, ITALY: SARDINIA, Aritzo, xi.1911 (D. Dodero) (Museo Civico di Storia Naturale, Genoa) [examined].

Determination Clarifications

Rigato (2011) - X. Espadaler (pers. comm.) has assigned the single specimen reported from Spain by Collingwood and Yarrow (1969) to Stenamma debile.

References