Stenamma llama, Branstetter, Michael G., 2013

Branstetter, Michael G., 2013, Revision of the Middle American clade of the ant genus Stenamma Westwood (Hymenoptera, Formicidae, Myrmicinae), ZooKeys 295, pp. 1-277 : 116-118

Stenamma llama sp. n. Worker: Figure 104; Map: Figure 105

Type material.

Holotype worker. GUATEMALA: Zacapa, 2km SE La Unión, 14.95284N 89.27655W ± 60m, 1450m, 14 May 2009 (LLAMA, collection Ba-B-03-4-04-13) [USNM, specimen CASENT0605236]. Paratypes: same data as holotype but 14.94654°N, 89.27600°W ± 6m, 1550m, 12 May 2009 (LLAMA, Wa-B-03-1-01) [1w, CAS, CASENT0604931]; 14.94711°N, 89.27677°W ± 50m, 1550m, 12 May 2009 (LLAMA, Wa-B-03-1-36) [1w, MGBPC, CASENT0604952]; 14.95436°N, 89.27690°W ± 50m, 1430m, 12 May 2009 (LLAMA, Wa-B-03-2-10) [1w, MCZ, CASENT0604975], [1w, UCD, CASENT0606186], [1w, UNAM, CASENT0604974]; 14.95369°N, 89.27614°W ± 50m, 1430m, 12 May 2009 (LLAMA, Wa-B-03-2-32) [1w, UVGC, CASENT0604982].

Worker diagnosis.

Integument black to brown-black; medium-sized species (see HL, ML, PrW below); anterior margin of clypeus with shallow median emargination; basal margin of mandible straight, without notch or substantial depression; head and mesosoma mostly smooth and shining; mesosoma compact, with promesonotum distinctly bulging; petiolar node robust, tall, and distinctly angled posteriad; propodeal spines forming short broad triangles (PSL 0.09-0.14, PSI 1.7-2.5); setae on gastral tergites sparse, long, and suberect; eye of moderate size (EL 0.11-0.15, REL 19-23), oval-shaped, with 6-8 ommatidia at greatest diameter; frontal lobes narrow, not obscuring torular lobe in full-face view (FLD 0.14-0.18, FLI 25-28). Similar species: Stenamma lobinodus , Stenamma tiburon .

Geographic range.

Southern Mexico to Guatemala.

Worker description.

(8 measured) HL 0.59-0.72 (0.70), HW 0.56-0.69 (0.64), FLD 0.14-0.18 (0.17), PCW 0.05-0.07 (0.06), SL 0.46-0.56 (0.55), EL 0.11-0.15 (0.14), ACL 0.45-0.53 (0.52), ML 0.76-0.99 (0.90), PrW 0.41-0.55 (0.50), PSL 0.09-0.14 (0.12), SDL 0.05-0.08 (0.07), PL 0.31-0.41 (0.38), PH 0.23-0.31 (0.31), PW 0.14-0.20 (0.19), PPL 0.17-0.21 (0.21), PPW 0.18-0.26 (0.23), MFL 0.52-0.65 (0.63), MTL 0.39-0.50 (0.48), CI 92-96 (92), SI 80-85 (85), REL 19-23 (21), FLI 25-28 (27), PSI 1.7-2.5 (1.8), MFI 101-113 (101), ACI1 65-70 (68), ACI2 91-98 (95).

Medium-sized species; general body color black to red- or brown-black, with mandibles and appendages lighter, usually dark brown to yellow-brown; setae light brown; mandible with 6 teeth, consisting of 3 distinct apical teeth, a basal tooth, and 2 inner teeth, which are often worn and indistinct; basal margin of mandible relatively straight, without any notch or significant depression; dorsal surface of mandible mostly smooth and shining, with scattered piligerous punctae and a few short basal striae; median lobe of clypeus with pair of very faint vestigial carinulae that diverge toward anterior margin, apex with a short transverse carinula, remainder of clypeus mostly smooth and shiny; posterior extension of clypeus between frontal lobes moderately broad (PCW 0.05-0.07), with subparallel to slightly diverging sides; frontal lobes narrow, not obscuring torular lobes in full-face view; head roughly oval-shaped (CI 92-96), but appearing somewhat tear drop-shaped because of the angled anterior margin of the clypeus and position of eyes; posterior margin of the head flat, never distinctly depressed medially; eye of moderate size (EL 0.11-0.15, REL 19-23), oval-shaped, with 6-8 ommatidia at greatest diameter; face almost completely smooth and shining, with scattered piligerous punctae and a few longitudinal carinulae on gena; scape short (SI 80-85), not reaching posterior margin of head when laid back; scape mostly smooth and shining, with scattered piligerous punctae, and sometimes a few fine striae; flagellum with a distinct 4-segmented antennal club; mesosoma usually mostly smooth and shiny, with some longitudinal carinae in metanotal groove, and a few scattered rugulae on propodeum, but some specimens with more developed sculpture on mesonotum, mesopleuron, and propodeum, consisting of faint carinulae and punctae; promesonotum domed and distinctly bulging upwards above head and propodeum; promesonotal suture usually completely effaced dorsally, but in a few specimens pronotum appears separated from mesonotum; metanotal groove distinct and of moderate depth; propodeal spines short, forming broad triangles (PSL 0.09-0.14, PSI 1.7-2.5); petiole of moderate length (PL/HW 0.52-0.62), node in profile robust and very tall (PH/PL 0.66-0.80), with anterior face longer and more sloping than posterior face, dorsum of node distinctly angled posteriad, and almost reaching a sharp apex; postpetiole in profile subcircular to oval-shaped, somewhat globular, always smaller than petiolar node (PPH/PH 0.70-0.84), dorsum usually with a somewhat distinct longitudinal median lobe; petiole and postpetiole mostly punctate, sometimes with faint rugulae, anterior faces of nodes smooth and shiny; gaster smooth and shiny except scattered piligerous punctae; most of body with moderately long, erect to subdecumbent setae; scapes with subdecumbent to decumbent setae; setae on legs mostly decumbent to appressed, with some suberect setae on femoral venters and coxae.

Queen.

Unknown.

Male.

Unknown.

Biology.

Stenamma llama is a cloud forest specialist occurring from approximately 1100 m to 1600 m elevation. All specimens are known from sifted leaf litter collected from the forest floor, except for one, which was found at a cookie bait card. It is a rare species currently known from only one site in Oaxaca, Mexico, and one site in Guatemala. At the Guatemala site, out of 100 mini-Winkler and six maxi-Winkler samples, only six specimens were collected. The completely smooth and shiny integument of Stenamma llama suggests that it nests in a relatively wet microhabitat.

Comments.

With its mostly smooth sculpture and bulging promesonotum, Stenamma llama is a very recognizable species. These characters, along with those in the key and diagnosis, should make it easy to separate from all other Stenamma species.

Stenamma llama , along with Stenamma lobinodus and Stenamma tiburon , belongs to the lobinodus species group. Diagnostic features of the group are discussed below under Stenamma lobinodus .

Material examined.

GUATEMALA:Zacapa: 2km SE La Unión, 14.94711°N, 89.27677°W, 1550m, 12 May 2009 (LLAMA); MEXICO:Oaxaca: 10.8km SW Valle Nacional, 17.68102°N, 96.33026°W, 1120m, 13 Aug 2009 (M. G. Branstetter); 13.2km SW Valle Nacional, 17.65934°N, 96.33426°W, 1360m, 11 Aug 2009 (M. G. Branstetter); 14.8km SSW Valle Nacional, 17.64483°N, 96.33637°W, 1370m, 13 Aug 2009 (M. G. Branstetter).