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Species: Stenamma tico   Branstetter, 2013 

Classification:
Download Data

Taxonomic History (provided by Barry Bolton, 2019)

Stenamma tico Branstetter, 2013 PDF: 258, figs. 162-164 (w.q.) COSTA RICA. Neotropic. AntCat AntWiki

Overview:

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.

Distribution:

  Geographic regions (According to curated Geolocale/Taxon lists):
    Americas: Costa Rica, Nicaragua, Panama
  Biogeographic regions (According to curated Bioregion/Taxon lists):
    Neotropical

Distribution Notes:

Nicaragua to Panama.

Biology:

Stenamma tico is restricted to wet forest habitats from sea level to about 1500 m, being most abundant at mid elevations. Nearly all specimens come from extracts of sifted leaf litter taken from the forest floor. Once at a site in Nicaragua Branstetter (2013) 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. Stenamma tico has large, bulging eyes and it may be that it is more active at night than S. diversum. At the time of Branstetter's revision, the nest of S. tico was unknown. He speculated that it might have a nest structure similar to S. diversum, its close relative. Stenamma diversum nests in clay banks and has a characteristic flared turret at the entrance. Longino (see below) found the first nest of S. tico. It was a small carton nest under a leaf. In spite of being made from carton, the nest entrance was the same flaring turret seen at the entrance to nests of S. diversum.

J. Longino, 22 June 2014: I found a nest of S. tico (Longino collection JTL8664). I was in the Penas Blancas Valley, east of Monteverde, in Costa Rica. I was collecting at night and first saw about 5 workers dispersed on the surface of a small aroid leaf, each worker holding a larva, like a panic evacuation. On the underside of the leaf was a small carton nest with a turret-like nest entrance formed out of carton. The nest was circular, 20mm diameter, 5mm tall. Three nearby leaves of the same vine had irregular circles of carton material on the undersurface that looked like remnants of previous nests.

Images of the S. tico nest were taken by Theo Sumnicht:
Dorsal view (click here)
Lateral view (click here)
Another lateral view (click here)
Oblique view (click here)
Dissected nest, interior view (click here)

Identification:

Worker diagnosis. 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.

Similar species: Stenamma diversum, S. lobinodus

     Worker description. (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 S. 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 23-24), 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 ¾ 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 description. (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 specimen INB0003732299.
     Male. Unknown.

Comments:

Stenamma tico and S. diversum together form the diversum species group (diagnosis given under "comments" section under S. diversum).

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 S. diversum. Stenamma 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 S. 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.

Taxonomic Notes:

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) [INBio, specimen CASENT0622416]. Paratypes: same data as holotype [1w, CAS, CASENT0622417], [1w, FMNH, CASENT0600104], [1w, ICN, CASENT0623501], [1w, INBio, CASENT0623502], [1w, JTLC, CASENT0623503], [1w, LACM, CASENT0623504], [1w, MGBPC, CASENT0623505], [1w, MCZ, CASENT0623506], [1w, MZSP, CASENT0623507], [1w, UCD, CASENT0622414], [1w, USNM, CASENT0622415].

References:

Branstetter, M. G. 2012. Origin and diversification of the cryptic ant genus Stenamma Westwood (Hymenoptera: Formicidae), inferred from multilocus molecular data, biogeography and natural history. Systematic Entomology 37:478-496. 10.1111/j.1365-3113.2012.00624.x.

Branstetter, M. G. 2013. Revision of the Middle American clade of the ant genus Stenamma Westwood (Hymenoptera, Formicidae, Myrmicinae). ZooKeys 295:1-277. doi: 10.3897/zookeys.295.4905.

Specimen Habitat Summary

Found most commonly in these habitats: 53 times found in montane wet forest, 25 times found in mature wet forest, 20 times found in cloud forest edge, near dairy farm pasture, some big trees in rocky areas, probably disturbed primary or old second growth, on a steep slope, 9 times found in cloud forest, 6 times found in ridgetop cloud forest, 10 times found in cloud forest, primary, along steep ridge near peak, 3 times found in tropical wet forest, 7 times found in ridgetop cloud forest, isolated peak with oak trees, 8 times found in riparian forest, cloud forest along stream, near dairy farm pasture, 2nd growth or disturbed primary, 4 times found in wet forest, ...

Found most commonly in these microhabitats: 92 times ex sifted leaf litter, 29 times Hojarasca, 1 times Hojarasca, pasture edge, 11 times at bait, 1 times carton nest under leaf, 1 times pan trap, 2 times on clay bank, 2 times ex sifted litter from forest floor, 2 times ex sifted leaf litter on ground, 1 times bajo de M/16, 1 times A lo largo del sendero hacia arriba., ...

Collected most commonly using these methods: 78 times miniWinkler, 30 times Mini Winkler, 13 times Winkler, 11 times baiting, 7 times maxiWinkler, 6 times search, 2 times Berlese, 2 times flight intercept trap, 2 times Malaise, 1 times Pan Trap, 1 times 6L sifted litter, extracted in Winkler sack over ~18 hours, ...

Elevations: collected from 50 - 1650 meters, 981 meters average

Type specimens: Holotype Stenamma tico: casent0622416; Paratype Stenamma tico: casent0600104, casent0622414, casent0622415



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