Stenamma megamanni occurs from 700–2800 m, but it is most common from 1400–2000 m (there is also one dubious record from 150 m at Pico Bonito). It mainly inhabits montane wet forest environments, such as cloud forest, oak-pine forest, riparian forest, and mesophyll forest. Specimens have been collected in samples of sifted leaf litter, by baiting, by use of a Malaise trap, and by searching. Nests are known from rotting logs, under rocks, in mud and clay banks, and in dead bark. Most collections of this species have been inside closed-canopy forest, but it has been found several times nesting in clearings near cloud forest (similar to S. manni). The highest record of the species was a log nest in a clearing between lower elevation cloud forest and higher elevation pine forest.
Southern Mexico to Nicaragua. No records from Belize or El Salvador.
Worker diagnosis. Integument mostly black to red-black; medium- to large-sized species (see HL, ML, PrW below); lateral apex of hypostomal bridge projecting ventrally as a subquadrate to broadly rounded lobe, visible behind base of mandible in profile view; propodeal spines tuberculate (PSL 0.10–0.15, PSI 1.0–1.2); face and mesosoma usually completely sculptured with rugoreticulae and some carinulae (rarely with sculpture reduced); eye of moderate to large size (EL 0.14–0.19, REL 15–20), oval-shaped, with 8–11 ommatidia in greatest diameter; postpetiole usually appearing smaller than petiolar node (PPH/PH 0.85–0.98); basal margin of mandible straight to slightly sinuous; anterior clypeal margin with a median emargination.
Similar species: Stenamma manni.
Worker description. (12 measured) HL 0.93–1.15 (1.07), HW 0.80–1.08 (0.98), FLD 0.22–0.29 (0.25), PCW 0.05–0.10 (0.07), SL 0.79–0.98 (0.91), EL 0.14–0.19 (0.17), ACL 0.70–0.86 (0.78), ML 1.18–1.48 (1.36), PrW 0.53–0.69 (0.63), PSL 0.10–0.15 (0.12), SDL 0.09–0.14 (0.11), PL 0.40–0.54 (0.45), PH 0.25–0.32 (0.30), PW 0.18–0.25 (0.23), PPL 0.23–0.33 (0.26), PPH 0.21–0.31 (0.26), PPW 0.23–0.30 (0.28), MFL 0.97–1.23 (1.14), MTL 0.72–0.93 (0.85), CI 86–96 (91), SI 89–100 (93), REL 15–20 (18), FLI 25–28 (26), PSI 1.0–1.2 (1.1), MFI 82–90 (86), ACI1 61–63 (62), ACI2 84–89 (86). Medium- to large-sized species; general body color black to red-black, with appendages black or dark brown to orange-brown, becoming lighter toward extremities at joints; setae dark golden brown to golden brown; mandible with 6 teeth, 2 teeth nearest basal tooth sometimes worn and indistinct; basal margin of mandible straight to slightly sinuous, without a basal depression or notch; mandible mostly smooth, with scattered piligerous punctae and a few striations near base and on lateral surface; anterior clypeal margin with a simple median emargination; median lobe of clypeus usually with a pair of longitudinal carinulae (type population), but sometimes surface smooth, or with several irregular carinulae, area in between carinulae often depressed; apex of lobe usually with a single transverse short carinula (type population), but sometimes with several transverse carinulae/rugulae; remainder of clypeus smooth and shiny; posterior extension of clypeus between antennal insertions of moderate width (PCW 0.05–0.10), sides subparallel; frontal lobes of moderate width (FLD 0.22–0.29; FLI 25–28) not greatly obscuring torular lobes in full-face view; lateral margin of hypostomal bridge with a projecting subquadrate lobe, visible in profile view (very rarely reduced and only visible from a lateroventral view); head roughly oval-shaped to more robust, becoming strongly heart-shaped (CI 86–96), posterior margin of head with a distinct median depression (especially in larger specimens); eye moderately large (EL 0.14–0.19, REL 15–20), oval-shaped, with 8–11 ommatidia at greatest diameter; face sculpture variable, usually strongly rugoreticulate, with some carinulae along midline (type population), but sometimes sculpture more polished, with area near posterior margin of head becoming somewhat smooth; scape of moderate length (SI 89–100), reaching posterior margin of head when laid back; scape usually thick and robust, surface carinate to carinulae with piligerous punctae; flagellum with a somewhat indistinct 4-segmented antennal club; mesosoma sculpture variable, often densely rugose, with rugae wavy, almost becoming reticulate (type population), but sculpture often reduced, with promesonotum longitudinally carinulate to nearly smooth, and side of propodeum and mesopleuron more punctate; promesonotum in profile domed, and usually asymmetrical (type population), with apex shifted anterior of midpoint, but sometimes promesonotum symmetrical; metanotal groove well- demarcated, sometimes somewhat wide and with metanotum forming a small welt (type population); propodeal spines tuberculate (PSL 0.10–0.15, PSI 1.0–1.2); petiole of moderate length, usually somewhat robust (PL/HW 0.45–0.52); petiolar node in profile of moderate height (PH/PL 0.59–0.68), dorsum usually broadly rounded and pointing vertically, only rarely forming a sharp apex; postpetiole in profile usually appearing smaller than petiolar node (PPH/PH 0.85–0.98); petiole and postpetiole usually strongly punctate, with a few rugulae on dorsum and anterior face of postpetiolar node (type population), sometimes anterior faces of petiolar and petiolar nodes mostly smooth; gaster mostly smooth, with scattered piligerous punctae; most of body dorsum with relatively long standing pilosity; pilosity on gastral dorsum sparse and mostly suberect (type population), usually with some shorter subdecumbent setae, suberect setae often somewhat stout; setae on promesonotum often noticeably erect; setae on scape uniformly suberect to decumbent; setae on legs mostly decumbent to appressed, with some suberect setae on femoral venters and coxae. Queen description. (5 measured) HL 1.01–1.12 (1.11), HW 0.92–1.03 (0.99), FLD 0.27–0.31 (0.31), PCW 0.07–0.10 (0.09), SL 0.87–0.97 (0.95), EL 0.26–0.28 (0.28), ACL 0.76–0.83 (0.83), ML 1.55–1.72 (1.71), PrW 0.93–1.04 (0.99), PSL 0.20–0.23 (0.20), SDL 0.15–0.17 (0.16), PL 0.57–0.60 (0.60), PH 0.33–0.39 (0.36), PW 0.26–0.31 (0.30), PPL 0.30–0.34 (0.34), PPH 0.32–0.39 (0.38), PPW 0.35– 0.40 (0.38), MFL 1.13–1.26 (1.26), MTL 0.86–0.96 (0.93), CI 89–92 (89), SI 93–96 (96), REL 28–29 (28), FLI 28–31 (31), PSI 1.2–1.4 (1.2), MFI 78–84 (78), ACI1 60–62 (60), ACI2 83–89 (87). Same as worker except for standard queen modifications and as follows: pronotum with transverse rugulae; mesoscutum longitudinally costulate; scutellum rugose to rugoreticulate; propodeum rugose to rugoreticulate; postpetiolar node larger, and somewhat anteroposteriorly compressed; mesopleuron mostly smooth; setae on mesoscutum short; setae on gastral dorsum often more dense, and more strongly bilayered, with layer of decumbent setae more dense; anterior quarter of gastral dorsum often with a layer of pubescence under stouter suberect and decumbent setae; wing venation as in specimen CASENT0604840. Male. See specimen JTLC000007293. Note the rather peculiar propodeal protuberances. I have observed these in several specimens from different sites. Many males, however, including males from the same nest, have only small sharp tubercles.
This species belongs to the Middle American clade of Stenamma (see Branstetter 2012). All conent on this page modified from Branstetter (2013) unless noted otherwise.
