Stenamma andersoni, 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 : 34-36

Stenamma andersoni sp. n. Worker: Figure 51; Map: Figure 50

Type material.

Holotype worker. MÉXICO, Oaxaca: 10.9km N. Candelaria, [ca. 16.220°N, 95.891°W], 990m, 12 Jul 1987, cloud forest, ex sifted leaf litter (R. S. Anderson, collection RSA87-15) [USNM, specimen CASENT0604603]. Paratype: same data as holotype [1w, UNAM, CASENT0604602].

Worker diagnosis. Integument brown to red-brown (note that observed specimens are old, fresh specimens probably darker); small-sized species (see HL, ML, PrW below); anterior clypeal margin undulating, forming 2-4 small blunt teeth; basal margin of mandible sinuous, with a shallow basal depression, but without a basal tooth; head and pronotum mostly smooth and shiny; promesonotum in profile with relatively sharp transitions between anterior and dorsal faces, and between pronotum and mesonotum; pilosity on gastral tergites forming a layer of stout suberect setae, and a sparse layer of decumbent setae; eye of moderate size (EL 0.08-0.09, PSL 0.08-0.10), oval-shaped, with 5 ommatidia at greatest diameter; propodeal spines tuberculate (PSL 0.08-0.10, PSI 1.2-1.3); frontal lobes of moderate width (FLD 0.12-0.13, FLI 23-24), not obscuring torular lobes in full-face view. Similar species: Stenamma connectum , Stenamma crypticum , Stenamma huachucanum , Stenamma maximon .

Geographic range.

Southern Mexico.

Worker description.

(2 measured) HL 0.60-0.63 (0.63), HW 0.50-0.55 (0.55), FLD 0.12-0.13 (0.13), PCW 0.03 (0.03), SL 0.49-0.52 (0.52), EL 0.08-0.09 (0.09), ACL 0.47-0.49 (0.49), ML 0.76-0.81 (0.81), PrW 0.36-0.39 (0.39), PSL 0.08-0.10 (0.10), SDL 0.06-0.08 (0.08), PL 0.27-0.29 (0.29), PH 0.16-0.19 (0.19), PW 0.12-0.13 (0.13), PPL 0.15-0.16 (0.16), PPH 0.14-0.16 (0.16), PPW 0.16-0.17 (0.17), MFL 0.54-0.57 (0.57), MTL 0.42-0.45 (0.45), CI 85-88 (85), SI 95-98 (95), REL 16-17 (17), FLI 23-24 (23), PSI 1.2-1.3 (1.2), PI 53-54 (53), MFI 93-97 (97), ACI1 68 (68), ACI2 94-96 (94).

Small-sized species; general body color brown to red-brown (note observed specimens are older, fresh material almost certainly darker), with appendages lighter, brown to yellow-brown at extremities; setae golden; mandible with 6 teeth; basal margin of mandible sinuous, with a shallow basal depression, but no basal tooth; mandible mostly smooth, except for some conspicuous basal striae, and scattered piligerous punctae; anterior clypeal margin undulating, forming 2-4 small blunt teeth; median lobe of clypeus smooth, without noticeable carinulae, apex of lobe with a short transverse carinulae, remainder of clypeus smooth and shiny; posterior extension of clypeus between antennal insertions somewhat narrow (PCW 0.03), with sides subparallel; frontal lobes of moderate width (FLD 0.12-0.13, FLI 23-24), not obscuring torular lobes in full-face view; head roughly oval-shaped (CI 85-88), posterior margin with a slight median depression; eye of moderate size (EL 0.08-0.09, REL 16-17), oval-shaped, with 5 ommatidia at greatest diameter; face almost completely smooth and shiny, except for a few carinulae around frontal lobes and on genae, and scattered piligerous punctae; scape of moderate length (SI 95-98), not quite reaching posterior margin when laid back; scape surface mostly smooth, with faint striations, and scattered piligerous punctae; flagellum with a distinct 4-segmented antennal club; all of pronotum and most of mesonotal dorsum smooth and shiny, anepisternum rugose, katepisternum punctate, side of propodeum mostly punctate, with a few rugulae, dorsum and declivity of propodeum with transverse carinulae; promesonotum in profile low-domed, roughly symmetrical, with relatively sharp (and distinctive) transitions between anterior and dorsal faces, and between pronotum and mesonotum; metanotal groove of well-demarcated, of moderate width and depth; propodeal spines tuberculate (PSL 0.08-0.10, PSI 1.2-1.3); petiole appearing of moderate length (PL/HW 0.53-0.54); petiolar node in profile of moderate height (PH/PL 0.60-0.65), roughly symmetrical, with anterior and posterior faces almost equal in length, node dorsum rounded, but somewhat narrow, pointing vertically; postpetiole in profile subspherical, slightly smaller than petiolar node (PPH/PH 0.84-0.86); petiole and postpetiole mostly lightly punctate, with anterior faces of nodes smooth; gaster mostly smooth and shiny, with scattered piligerous punctae; most of body dorsum with thickened standing pilosity; pilosity on gastral tergites forming a layer of stout suberect setae, and a sparse layer of decumbent setae; setae on scapes dense, decumbent to appressed; setae on legs mostly appressed, with a few suberect to subdecumbent setae on femoral venters and coxae.

Queen.

Unknown.

Male.

Unknown.

Biology.

This species is recorded from a single Berlese sample of sifted leaf litter collected in cloud forest at 990 m elevation.

Comments.

Stenamma andersoni should be easy to separate from similar species by its smooth head and pronotum, unique pronotum shape, and thickened gastral setae.

Stenamma andersoni is known from only two specimens collected in 1987. As a result the specimens are somewhat faded in color and were not useable for molecular phylogenetic work. With morphology alone, it is not clear to which species Stenamma andersoni is most closely related, but I hypothesize that it is probably near Stenamma crypticum or Stenamma huachucanum .

Material examined.

Known only from the type locality.