This species is known only from Winkler or Berlese extractions of sifted leaf litter taken from montane, mesophyll forests. Nests have never been collected. It is likely a mid-elevation specialist given its occurrence between 860 to 1620 m.
At the El Cielo reserve in northern Mexico, Branstetter (2013) found a lone worker that looked like S. lobinodus foraging on a mud/clay bank bordering the main road (specimen viewed with a hand lens). Unfortunately the worker escaped and no nest was located. The presence of the worker on a mud bank suggests that S. lobinodus may nest in banks like the similar-looking S. diversum. Both species have almost the same sculpture, color and propodeal spines.
Mexico (Atlantic slope).
Worker diagnosis. Integument black to brown-black and shining; medium-sized species (see HL, ML, PrW below); anterior clypeal margin with shallow median emargination; basal margin of mandible relatively straight, without notch or substantial depression; face mostly smooth and shiny; mesosoma with coarse, rugose to rugoreticulate sculpture on most surfaces; promesonotum in profile distinctly asymmetrical, with anterior face gently rounded, dorsal surface flattened, and posterior face short, straight and forming a relatively sharp angle with dorsum; petiolar node, generally robust, and distinctly angled posteriad; postpetiolar node in profile with a longitudinal dorsal lobe that projects out posteriad over postpetiole; eye of moderate size (EL 0.11–0.14; REL 18-22), oval-shaped, with 7–8 ommatidia at greatest diameter; propodeal spines ranging from short tubercles to long spines (PSL 0.10–0.22, PSI 1.3-2.6); setae on gastral tergites relatively sparse, long, and mostly suberect; frontal lobes narrow, not obscuring torular lobe in full-face view (FLD 0.13-0.16, FLI 21-25).
Similar species: Stenamma diversum, S. tico.
Worker description. (10 measured) HL 0.65–0.76 (0.73), HW 0.57–0.71 (0.67), FLD 0.13–0.16 (0.15), PCW 0.03–0.05 (0.04), SL 0.52–0.62 (0.61), EL 0.11–0.14 (0.14), ACL 0.50–0.58 (0.56), ML 0.84–1.03 (0.97), PrW 0.41–0.51 (0.49), PSL 0.10–0.22 (0.20), SDL 0.06–0.09 (0.08), PL 0.35–0.44 (0.42), PH 0.23–0.29 (0.27), PW 0.14–0.18 (0.18), PPL 0.16–0.22 (0.21), PPH 0.16–0.19 (0.18), PPW 0.16–0.21 (0.20), MFL 0.59–0.71 (0.70) MTL 0.47–0.57 (0.55), CI 89–95 (92), SI 85–92 (90), REL 18–22 (21), FLI 21–25 (23), PSI 1.3–2.6 (2.4), PI 58–65 (62) MFI 96–103 (96), ACI1 64–68 (66), ACI2 90–100 (92). Medium-sized species; general body color black to brownor red-black, with mandibles and appendages lighter, usually dark brown to yellow-brown; setae golden; 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 a notch or significant depression; dorsal surface of mandible mostly smooth and shiny, with scattered piligerous punctae and a few short basal striae; median lobe of clypeus with a pair of vestigial longitudinal carinulae that diverge toward the 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 0.03-0.05), with subparallel to slightly diverging sides; frontal lobes narrow (FLD 0.13–0.16, FLI 21–25), not obscuring torular lobes in full-face view; head roughly oval-shaped (CI 89–95), but appearing somewhat tear drop-shaped because of the angled anterior margin of clypeus and position of eyes; posterior margin of head flat, never distinctly depressed medially; eye of moderate size (EL 0.11–0.14; REL 18-22), oval-shaped, with 7–8 ommatidia at greatest diameter; face almost completely smooth and shiny, with scattered piligerous punctae and few longitudinal carinulae on genae; scape moderately long (SI 85–92), nearly reaching posterior margin of head when laid back; scape surface largely smooth and shiny, with scattered piligerous punctae, and sometimes with a few faint striae; flagellum with distinct 4-segmented antennal club; mesosoma almost entirely with coarse rugae and rugoreticulae; rugae usually with a predominately longitudinal orientation, but in some specimens rugae on mesonotum have a transverse orientation; katepisternum, metapleuron, and lateral portion of pronotum, with a variably sized patch of smooth cuticle; propodeal dorsum and declivity with transverse carinulae; promesonotum in profile distinctly asymmetrical, with anterior face gently rounded, dorsal surface flattened, and posterior face short, straight and forming a relatively sharp angle with dorsum; promesonotal suture indistinct, but usually discernable, especially when the orientation of the pronotal and mesonotal rugae differ; metanotal grove distinct and of moderate depth; propodeal spines present and often relatively long, but sometimes (usually specimens from lower elevations) becoming reduced to short tubercles (PSL 0.10–0.22, PSI 1.3–2.6); petiole in profile relatively long (PH/HW 0.58–0.65) and very distinctive, having a long peduncle and robust node, which is markedly angled posteriad; petiolar node in profile with long sloping anterior face that begins at about middle of peduncle, posterior face shorter, but usually at a similar angle, dorsum of node broadly rounded to subquadrate; postpetiole in profile asymmetrical, with a long sloping anterior face, and a short nearly vertical posterior face, dorsum with a distinct longitudinal lobe that projects out slightly posteriad over postpetiole, lobe in dorsal view attenuating posteriad, giving it a pinched-in appearance; petiole and postpetiole with variable amount of rugae and punctae; anterior faces of nodes mostly smooth and shiny with remaining surfaces punctatorugose; punctae most visible on ventral surfaces; posterior slope of petiolar node sometimes with a median keel; in a few aberrant populations the petiole and postpetiole lack rugae and are almost completely punctate; gaster smooth and shiny, with scattered piligerous punctae; most of body with sparse layer of moderately long standing seate; setae on scape mostly subdecumbent; setae on remaining appendages suberect to decumbent, with longer suberect setae on femoral venters and coxae. Queen description. (5 measured) HL 0.71–0.77 (0.72), HW 0.67–0.73 (0.67), FLD 0.16–0.17 (0.16), PCW 0.03–0.05 (0.03), SL 0.58–0.63 (0.58), EL 0.17–0.19 (0.17), ACL 0.55–0.60 (0.56), ML 1.03–1.16 (1.03), PrW 0.60–0.65 (0.60), PSL 0.17–0.23 (0.17), SDL 0.08–0.11 (0.09), PL 0.41–0.49 (0.41), PH 0.26–0.31 (0.28), PW 0.19–0.22 (0.19), PPL 0.20–0.24 (0.22), PPH 0.20–0.24 (0.21), PPW 0.23– 0.26 (0.23), MFL 0.67–0.74 (0.67), MTL 0.53–0.60 (0.53), CI 93–97 (93), SI 84–89 (87), REL 26–27 (26), FLI 23–24 (24), PSI 1.9–2.5 (1.9), MFI 98–102 (100), ACI1 66–69 (66), ACI2 94–96 (95). Same as worker except for standard queen modifications and as follows: lateral surfaces of pronotum transversely rugose to rugoreticulate, median area smooth and shiny; mesoscutum longitudinally carinate, with carinae fanning out from middle of anterior margin; mesopleuron mostly smooth and shiny; wing venation as in specimen CASENT0605697. Male. See specimen CASENT0605698.
This species belongs to the Middle American clade of Stenamma (see Branstetter 2012). All content on this page modified from Branstetter (2013) unless noted otherwise.
