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Taxonomic History (provided by Barry Bolton, 2017)

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:

(based on species list records)
Neotropical Region: Americas, Central America, Cortés, Honduras, Jinotega, Nicaragua, Olancho

Distribution Notes:

Honduras to Nicaragua.

Biology:

Stenamma picopicucha occurs from 1400–2300 m elevation, and is a specialist of montane wet forest habitats, such as cloud forest and dwarf forest. Most collections of this species are from samples of sifted leaf litter taken from the forest floor, but a few specimens are known from cookie bait cards. Nests have never been found, but dealate queens are common in the leaf litter, suggesting that nests might occur within this stratum.

Identification:

Worker diagnosis. Integument mostly dark brown to brown; small-sized spe- cies (see HL, ML, PrW below); basal margin of mandible straight, without a basal notch or depression; anterior clypeal margin forming two blunt teeth, which border the midline; face completely sculptured, mostly rugoreticulate; mesosoma completely sculptured, pronotum longitudinally rugose; pilosity on gastral dorsum bilayered, with a layer of long suberect setae, and a layer of very sparse decumbent setae; eye of moderate size (EL 0.10–0.12, REL 17–20), oval-shaped, with 5–6 ommatidia at greatest diameter; propodeal spines tuberculate to short (PSL 0.08–0.10, PSI 1.3–1.6). Similar

Similar species: Stenamma crypticum, S. huachucanum, S. ignotum.

     Worker description. (11 measured) HL 0.59–0.69 (0.69), HW 0.52–0.64 (0.64), FLD 0.14–0.15 (0.15), PCW 0.03–0.05 (0.05), SL 0.46–0.55 (0.55), EL 0.10–0.12 (0.12), ACL 0.45–0.53 (0.53), ML 0.71–0.84 (0.84), PrW 0.37–0.42 (0.42), PSL 0.08–0.10 (0.09), SDL 0.06–0.07 (0.07), PL 0.25–0.30 (0.30), PH 0.16–0.19 (0.19), PW 0.13–0.15 (0.15), PPL 0.14–0.18 (0.18), PPH 0.16–0.18 (0.18), PPW 0.16– 0.19 (0.19), MFL 0.48–0.59 (0.59), MTL 0.41–0.51 (0.51), CI 89–94 (93), SI 85–89 (86), REL 17–20 (18), FLI 23–28 (23), PSI 1.3–1.6 (1.5), MFI 104–109 (108), ACI1 67–70 (69), ACI2 96–101 (96).
     Small-sized species; general body color mostly dark brown to brown, with appendages brown to orange-brown, lighter at joints and toward extremities; setae golden brown; mandible with 6 teeth, inner two teeth near basal tooth, sometimes worn; basal margin of mandible straight, without a basal notch or depression; mandible surface mostly smooth, with scattered piligerous punctae and some faint striations on base and lateral surface; anterior clypeal margin forming 2 blunt teeth, which border the midline; median lobe of clypeus with a pair of faint longitudinal carinulae, which diverge anteriorly, apex of lobe with a short transverse carinula, area in between lobe and anterior clypeal margin forming a distinct cavity, remainder of clypeal surface smooth; posterior extension of clypeus between antennal insertions of moderate width (PCW 0.03–0.05), with sides subparallel; frontal lobes of moderate width (FLD 0.14–0.15, FLI 24–28), not greatly covering torular lobes in full-face view; head subrectangular (CI 89–94), posterior margin with a slight median depression; eye of moderate size (EL 0.10–0.12 , REL 17–20), oval-shaped, with 5–7 ommatidia at greatest diameter; face mostly rugoreticulate, with some longitudinal carinulae along midline; scape somewhat short (SI 85–89), not quite reaching posterior margin of head when laid back; scape surface mostly smooth, with scattered piligerous punctae; flagellum with a somewhat distinct 4-segmented antennal club; mesosoma completely sculptured; pronotal dorsum longitudinally rugose, becoming rugoreticulate-punctae on mesonotal dorsum; side of pronotum rugose to rugose-punctate; katepisternum and side of propodeum mostly punctate, with a few rugulae on propodeum; propodeal dorsum mostly punctate, with a few transverse carinulae; propodeal declivity with transverse carinulae; promesonotum in profile slightly asymmetrical, with the anterior face long and steeper than posterior face; metanotal groove relatively distinct, but anterior slope transitioning smoothly into promesonotum; propodeal spines tuberculate (PSL 0.08– 0.10, PSI 1.3–1.6); petiole in profile short (PL/HW 0.46–0.50); petiolar node usually small, somewhat dorsoventrally compressed (PH/PL 0.60–0.68), node asymmetrical in profile, anterior face longer and more sloping than nearly vertical posterior face, dorsum of node narrowly rounded, and pointing slightly posteriad; postpetiolar node in profile usually similar in size to petiolar node (type population), but sometimes bulging (PPH/PH 0.90–1.01); petiole and postpetiole usually mostly punctate, with only the anterior faces of the nodes smooth, but sometimes nodes mostly smooth; most of body dorsum with short to moderately long pilosity; pilosity on gastral dorsum bilayered, with a layer of long suberect setae, and a much sparser layer of short decumbent setae; setae on scape subdecumbent to appressed; setae on legs decumbent to appressed, with longer suberect setae on femoral venters and coxae.
     Queen description. (5 measured) HL 0.63–0.71 (0.64), HW 0.60–0.67 (0.61), FLD 0.16–0.17 (0.17), PCW 0.04–0.05 (0.03), SL 0.49–0.56 (0.47 (0.47), EL 0.17– 0.20 (0.18), ACL 0.47–0.53), ML 0.91–1.05 (0.93), PrW 0.52–0.61 (0.54), PSL 0.12–0.14 (0.12), SDL 0.08–0.10 (0.09), PL 0.31–0.36 (0.32), PH 0.18–0.21 (0.19), PW 0.15–0.18 (0.16), PPL 0.17–0.21 (0.19), PPH 0.19–0.22 (0.19), PPW 0.20– 0.24 (0.21), MFL 0.54–0.65 (0.55), MTL 0.46–0.56 (0.46), CI 94–96 (95), SI 81–84 (78), REL 29–30 (29), FLI 24–27 (28), PSI 1.4–1.6 (1.4), MFI 104–110 (109), ACI1 67–69 (68), ACI2 94–98 (101).
     Same as worker except for standard queen modifications and as follows: pronotum with transverse carinulae; mesoscutum and scutellum carinulae; mesopleuron mostly smooth and shiny; propodeum transversely carinulate, with carinulae wrapping around surface; decumbent layer of setae on dorsum of gaster more dense.
     Male. Unknown.

Comments:

Stenamma picopicucha looks like a cross between S. crypticum and S. ignotum. The petiole and anterior clypeal margin are more like S. crypticum, but the basal margin of the mandible and gastral pilosity are more similar to S. ignotum. Branstetter (2013) originally intended to lump this species in with S. crypticum until it was noticed that the two species occur in sympatry near the peak at Cusuco in Honduras. It is interesting to note that this mountaintop population at Cusuco has the postpetiole bulging and smooth; as a consequence, this form is given the label variant 1 (CASENT0622155). This population is most likely the same as S. picopicucha based on mandible and clypeus structure. More normal-looking specimens occur at lower elevation on the mountain.

Taxonomic Notes:

Type material. Holotype worker. HONDURAS, Olancho: 11km N Catacamas, 14.94839°N, 85.91477°W ±20m, 2020m, 8 May 2010, cloud forest, ex sifted leaf litter (LLAMA, collection Wa-C-02-1-03) [USNM, specimen CASENT0621356]. Paratypes: same data as holotype [1w, CAS, CASENT0621355], [1w, EAPZ, CASENT0621357], [1w, ECOSCE, CASENT0621358], [1w, FMNH, CASENT0623456], [1w, ICN, CASENT0623457], [1w, INBio, CASENT0623458], [1w, JTLC, CASENT0623459], [1w, LACM, CASENT0623461], [1w, MGBPC, CASENT0623462], [1w, MCZ, CASENT0623463], [1w, MZSP, CASENT0623464], [1w, UCD, CASENT0623465], [1w, UNAM, CASENT0623467], [1w, UVGC, CASENT0623468]; same data but 14.94879°N, 85.91486°W ±20m, 2020m, 8 May 2010 (LLAMA, Wa-C-02-1-12) [1dq, 2w, USNM, CASENT0621374, CASENT0621372, CASENT0621373].

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: 142 times found in cloud forest, 5 times found in mixed hardwood forest, 8 times found in ridgetop cloud forest, 1 times found in oak-pine forest, 1 times found in wet cloud forest, 1 times found in dwarf forest, 1 times found in tropical montane forest.

Found most commonly in these microhabitats: 153 times ex sifted leaf litter, 6 times at bait.

Collected most commonly using these methods: 129 times MiniWinkler, 23 times MaxiWinkler, 6 times baiting, 1 times Winkler.

Elevations: collected from 1350 - 2230 meters, 1887 meters average

Type specimens: Holotype Stenamma picopicucha: casent0621356; Paratype Stenamma picopicucha: casent0621355, casent0621357, casent0621358, casent0621372, casent0621373, casent0621374

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