Stenamma tico

Stenamma tico is restricted to wet forest habitats from sea level to about 1500 m, being most abundant at mid elevations. Nests have never been collected of this species, with nearly all specimens coming from extracts of sifted leaf litter taken from the forest floor. Once at a site in Nicaragua I found a trail of workers migrating across a clay bank in montane wet forest. Although a nest site could not be found, the number of workers involved suggests that they were relocating the nest. The presence of S. tico on clay banks indicates that it may have biological characteristics very similar to the closely related Stenamma diversum, which is known to nest in clay bank environments. Stenamma tico has large, bulging eyes and it may be that it is more active at night than S. diversum.

Identification
Key to Middle America Stenamma

Branstetter (2013) - Integument shining, largely black to red-black; medium-sized species (see HL, ML, PrW below); head mostly smooth and shiny; mesosoma reticulately costate to coarsely rugoreticulate; propodeal spines reduced to small upward projecting points, or sharp right angles at interface between dorsal and declivitous faces of propodeum (PSL 0.14–0.18, PSI 1.4-1.9); eyes large and somewhat bulging (EL 0.15–0.18, REL 23-24), with 7–10 ommatidia at greatest diameter; anterior margin of clypeus with shallow median emargination; basal margin of mandible straight, without notch or substantial depression; pilosity on gastral dorsum long, flexuous, and relatively sparse.

Within its range S. tico is unlikely to be confused with any other species. Only in northern Nicaragua does it occur in sympatry with its sister species Stenamma diversum. S. tico can be separated from S. diversum by its smaller propodeal spines and narrower frontal lobes. Stenamma tico also can be separated from S. diversum, as well as from the similar looking Stenamma lobinodus, by its relatively long scape (SI > 95 vS. < 93) and metafemur (MFI < 89 vS. > 94). Stenamma tico shows some elevational variation with specimens from higher localities becoming larger, darker and more sculptured (especially on the face). This variation appears to be continuous, and thus is unlikely due to the existence of cryptic species.

Distribution
Nicaragua to Panama.

Distribution based on Regional Taxon Lists
Neotropical Region: Costa Rica, Nicaragua, Panama.

Castes
Males have not been collected.

Nomenclature

 *  tico. Stenamma tico Branstetter, 2013: 258, figs. 162-164 (w.q.) COSTA RICA.

Worker
(11 measured) HL 0.71-0.85 (0.84), HW 0.63-0.76 (0.76), FLD 0.22-0.27 (0.26), PCW 0.06-0.07 (0.07), SL 0.60-0.77 (0.77), EL 0.15-0.18 (0.18), ACL 0.54-0.68 (0.68), ML 0.91-1.11 (1.11), PrW 0.48-0.58 (0.57), PSL 0.14–0.18 (0.14), SDL 0.08–0.10 (0.09), PL 0.37-0.46 (0.44), PH 0.21-0.26 (0.26), PW 0.16–0.22 (0.20), PPL 0.19–0.25 (0.23), PPH 0.19–0.25 (0.24), PPW 0.20–0.25 (0.25), MFL 0.72-0.91 (0.91), MTL 0.56-0.71 (0.71), CI 87-93 (91), SI 95-103 (101), REL 23-24 (24), FLI 33-36 (34), PSI 1.4-1.9 (1.4), MFI 82-88 (84), ACI1 63-66 (64) ACI2 84–91 (88).

Medium-sized species; general body color black to red-black, with brown patches on waist and gaster; mandibles, clypeus and appendages dark brown to yellow-brown; setae golden; mandible with 6–7 teeth, consisting of 3 distinct apical teeth, a basal tooth, and 2–3 inner teeth, which are often worn and indistinct; basal margin of mandible straight, without any notch or significant depression; dorsal surface of mandible mostly smooth and shiny, with scattered piligerous punctae and variable number of basal striae; median lobe of clypeus with a pair of vestigial longitudinal carinulae and/ or several ill-defined rugulae, apex of lobe with a short transverse carinula, remainder of clypeus smooth and shiny; posterior extension of clypeus between frontal lobes rather broad (PCW 0.06-0.07), with subparallel sides; frontal lobes relatively well developed, but not markedly expanded dorsolaterally (as in Stenamma diversum), nor completely obscuring the underlying torular lobes in full-face view; head roughly oval-shaped, slightly, but distinctly longer than broad (CI 87-93), posterior margin gently convex, never depressed medially; eyes relatively large and somewhat bulging (EL 0.15–0.18, REL 2324), oval-shaped, with 7–10 ommatidia at greatest diameter; face mostly smooth and shining, with variable amount of weak carinulae/rugulae and punctae confined to lower 3/4 of head; most specimens with some carinulae around antennal sockets and on gena, others with more extensive carinulae fanning outward from frontal carinae, sometimes with reticulae between antennal carinae and eyes; scape relatively long (SI 95-103), reaching and slightly surpassing posterior margin of head when laid back; dorsal surface of scape striate; flagellum with distinct 4-segmented antennal club; mesosoma shiny, almost entirely reticulately costate to coarsely rugoreticulae; propodeal declivity smooth, sometimes with a few transverse carinulae; promesonotum in profile low-domed and roughly symmetrically, anterior slope a little steeper and longer than posterior slope; propodeal spines reduced to small upward projecting points, or only forming sharp right angles where dorsal and declivitous surfaces of propodeum meet (PSL 0.14–0.18, PSI 1.4-1.9); petiole moderately long (PL/HW 0.57–0.63) and robust, node roughly half length of petiole and asymmetrical, with anterior face long and gradually sloping, and posterior face nearly vertical, but slightly angled so that apex of petiole points posteriad; dorsum of petiolar node viewed from posterior side weakly rounded; postpetiole in profile similar in size to petiolar node (PPH/PH 0.91–0.97), roughly circular, although with anterior face slightly longer and more sloping than posterior face; petiole and postpetiole shiny, nodes mostly smooth, with some rugulae and faint punctae on sides; venter of petiole and postpetiole weakly punctate; gaster mostly smooth and shiny, with scattered piligerous punctae; most of body with single layer of long standing setae; setae on legs and scapes varying from predominately suberect to mostly decumbent; coxae and femoral venters always with a row of longer suberect setae.

Queen
(5 measured) HL 0.71–0.85 (0.79), HW 0.63–0.76 (0.73), FLD 0.22–0.27 (0.24), PCW 0.07–0.09 (0.07), SL 0.64–0.78 (0.69), EL 0.20–0.24 (0.21), ACL 0.53–0.66 (0.60), ML 1.05–1.29 (1.12), PrW 0.57–0.70 (0.60), PSL 0.18–0.21 (0.19), SDL 0.09–0.11 (0.10), PL 0.43–0.53 (0.48), PH 0.24–0.29 (0.25), PW 0.20–0.25 (0.22), PPL 0.20–0.26 (0.23), PPH 0.23–0.29 (0.25), PPW 0.25–0.31 (0.26), MFL 0.77–0.94 (0.81), MTL 0.61–0.73 (0.64), CI 91–93 (93), SI 93–95 (94), REL 28–30 (28), FLI 34–37 (24), PSI 2.0–2.2 (2.0), MFI 87–90 (90), ACI1 63–66 (64), ACI2 82–90 (87).

Same as worker except for standard queen modifications and the following: face usually more sculptured, with light fan of rugulae/carinulae extending from frontal lobes to ocelli, sculpture around antennal sockets more distinct; costae on mesoscutum with a decidedly longitudinal orientation, but often wavy, and usually with some reticulation anteriorly; costae on side of promesonotum longitudinal in orientation; mesopleuron mostly smooth and shiny; propodeal spines always present, short, projecting dorsoposteriad (PSL 0.18–0.21, PSI 2.0–2.2); wing venation as in photo.

Type Material
Holotype worker. COSTA RICA, Heredia Prov.: 10km NE Vara Blanca, 10.233°N, 84.067°W, 1500m, 9 Mar 2005 (Project ALAS, collection 15/ WF/02) INBC, specimen CASENT0622416. Paratypes: same data as holotype 1w, CASC, CASENT0622417, 1w, FMNH, CASENT0600104, 1w, ICN, CASENT0623501, 1w, INBC CASENT0623502, 1w, JTLC, CASENT0623503, 1w, LACM, CASENT0623504, 1w, MGBPC, CASENT0623505, 1w, MCZ, CASENT0623506, 1w, MZSP, CASENT0623507, 1w, UCDC, CASENT0622414, 1w, USNM, CASENT0622415.