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Species: Octostruma triangulabrum   Longino, 2013 

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Taxonomic History (provided by Barry Bolton, 2022)

Octostruma triangulabrum Longino, 2013b PDF: 52, figs 1A, 3A, 5J, 38, 43 (w.) MEXICO (Chiapas). Neotropic. Primary type information: Primary type material: holotype worker. Primary type locality: Mexico: Chiapas, Nahá, 19.96291, -91.59335, ±2 km., 950 m.,, mesophil forest, ex sifted leaf litter (LLAMA Wm-A-07-all). Primary type depository: CASC. Primary type specimen: CASENT0608768. Secondary type information: Secondary type material: 9 paratype workers. Secondary type localities: paratype/s with same data as holotype, paratype/s with same data as holotype but 16.97417, -91.58592, ±50 m., 950 m., 14.vii.2007, #6047-s (J. Longino), and #2007-013 (R.S. Anderson), paratype/s with same data as holotype but 16.96313, -91.59337, ±50 m., 985 m., (LLAMA Wa-A-07-1-06), paratype/s with same data as holotype but 16.96318, -91.59337, ±50 m., 985 m., (LLAMA Wa-A-07-1-07), paratype/s with same data as holotype but 16.94866, -91.59392, ±50 m., 930 m., (LLAMA Wa-A-07-2-08). Secondary type depositories: CASC, CFSS, JTLC, MCZC, MZSP, UCDC, USNM, UVGC. AntCat AntWiki


A cryptic inhabitant of forest floor leaf litter and rotten wood; from montane forests in central Chiapas, Mexico. // Distribution


  Geographic regions (According to curated Geolocale/Taxon lists):
    Americas: Mexico
  Biogeographic regions (According to curated Bioregion/Taxon lists):

Distribution Notes:

Mexico (Chiapas).


Octostruma triangulabrum occurs in montane wet forest habitats, in both mesophyl cloud forest and wet pine-oak forests, throughout the central Chiapas highlands. It occurs from 900–2750 m elevation and can be moderately abundant (up to 13% of 1 m2 plot litter samples in quantitative sampling). It is only known from Winkler and Berlese samples of sifted leaf litter.


With the characters of O. wheeleri and O. triquetrilabrum. Differing from O. wheeleri in the presence of 8–12 spatulate setae on face (6 on O. wheeleri) and shallow reticulate rugulose sculpture on face and dorsal pronotum (nearly smooth on O. wheeleri). Differing from both species in a pair of spatulate setae on the mesonotum (lacking in O. wheeleri and O. triquetrilabrum).


This species and Costa Rica's O. triquetrilabrum are extremely similar allopatric forms, differing only in the presence or absence of mesonotal setae. Intensive sampling of the litter fauna in cloud forest sites in Nicaragua, Honduras, and Guatemala has failed to reveal additional populations. Both together are quite similar to the lowland O. wheeleri. Octostruma triangulabrum is sharply parapatric with O. wheeleri (see Comments under O. wheeleri).

The name refers to the triangular labrum that is not bilobed at the apex.

Specimen Habitat Summary

Found most commonly in these habitats: 14 times found in mesophil forest, 8 times found in montane wet forest, 1 times found in oak/pine forest, 1 times found in pine cloud forest, 1 times found in riparian mesophytic forest, 1 times found in wet oak pine forest, 1 times found in cloud forest, 1 times found in mixed montane wet forest.

Found most commonly in these microhabitats: 23 times ex sifted leaf litter, 4 times forest litter, 1 times leaf litter.

Collected most commonly using these methods: 20 times MiniWinkler, 6 times Berlese, 1 times MaxiWinkler, 1 times Winkler.

Elevations: collected from 930 - 2750 meters, 1142 meters average

Collect Date Range: collected between 1991-09-18 00:00:00.0 and 2016-06-03 00:00:00.0

Type specimens: holotype Octostruma triangulabrum Longino 2013: casent0608768; paratype Octostruma triangulabrum Longino 2013: casent0602034, casent0608761, casent0627348, casent0627349, casent0627350, jtlc000009758, jtlc000009759, jtlc000014462, jtlc000014488

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