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Species: Octostruma amrishi   (Makhan, 2007) 

Download Data

Taxonomic History (provided by Barry Bolton, 2021)

Pyramica amrishi Makhan, 2007a PDF: 1, figs. 1, 2 (w.) SURINAM. Neotropic. AntCat AntWiki

Taxonomic history

Combination in Octostruma: Bolton et al., 2008 PDF: 62.
Revived from synonymy: Longino, 2013b PDF: 15.


A cryptic inhabitant of leaf litter and rotten wood on the forest floor, lowland wet forests of Central and northern South America. // Distribution


  Geographic regions (According to curated Geolocale/Taxon lists):
    Americas: Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Guyana, Honduras, Nicaragua, Panama, Peru, Suriname, Venezuela
  Biogeographic regions (According to curated Bioregion/Taxon lists):

Distribution Notes:

Honduras to southern Peru and Amazonian Brazil.


Octostruma amrishi is a lowland to lower montane species. It occurs mostly in mature wet forest, less often in second growth forest. In the northern part of the range in Central America, where O. gymnogon does not occur, it extends into cloud forest to 1500 m. In southern Central America, where O. gymnogon occurs, it exhibits an elevationally parapatric distribution with O. gymnogon and is restricted to elevations below 600 m. Almost all collections are from Berlese and Winkler samples of sifted litter and rotten wood from the forest floor. Dealate queens and intercaste workers occasionally occur together with workers in litter samples. One collection was of foragers on clay soil in a rainforest. See additional comments under O. balzani.


Mandible with 8 teeth, tooth 1 a broad blunt lamella, strongly differentiated from tooth 2, teeth 2–5 acute, similar in shape, with denticles between them; teeth 5–8 forming an apical fork, with 5 and 8 large, 6 and 7 small partially confluent denticles (O. balzani complex); face lacking erect setae on posterolateral margins of head (present in O. balzani, O. megabalzani, and O. trithrix), a medial pair present on vertex margin (lacking in O. gymnogon); mesosomal dorsum usually lacking a pair of erect setae (present in O. balzani, O. megabalzani, and O. trithrix); metanotal groove usually not impressed in profile view (impressed in O. balzani, O. megabalzani). When sympatric with O. balzani, O. amrishi is often a lighter red brown.


Sampling of Octostruma is less thorough in South America than in Central America, but specimens that match the morphology of O. amrishi occur in lowland to midmontane rainforest in northern South America and throughout the Amazonian lowlands. Specimens from the southern portion of the range, including Amazonian Brazil and the eastern and western foothills of the Ecuadorian Andes, show reduced punctation on the first gastral tergite, becoming smooth and shining on a variable extent of the posterior portion of the tergite. See additional comments under O. balzani.

Although O. amrishi was poorly characterized in the original description, the characteristic setal pattern can be seen on the figures in the original publication.

15 Oct 2017: Molecular evidence now shows that "amrishi" as defined by Longino 2013 is polyphyletic. Costa Rican "amrishi" is sister to gymnogon. Panamanian "amrishi" are more related to trithrix and various balzani-like forms.

Specimen Habitat Summary

Found most commonly in these habitats: 81 times found in mature wet forest, 66 times found in montane wet forest, 40 times found in ridgetop cloud forest, 11 times found in forest, 18 times found in tropical wet forest, 18 times found in seasonally wet 2° tropical forest, 21 times found in tropical rainforest, with some big trees, probably a mix of primary and secondary forest, 20 times found in tropical rainforest, with big trees, probably primary, 5 times found in rainforest, 7 times found in cloud forest, ...

Found most commonly in these microhabitats: 300 times ex sifted leaf litter, 10 times Hojarasca, 4 times litter, 11 times leaf litter, 1 times nesting in dead snails, 1 times in Guadua litter, 3 times forest floor leaf litter, 1 times ex soil & fungus litter, 3 times ex sifted litter, 1 times rotten flowers of Pseudobombax, 1 times Parcelas susecionales, Suelo, ...

Collected most commonly using these methods: 230 times MiniWinkler, 37 times Berlese, 32 times MaxiWinkler, 24 times Winkler, 2 times search, 8 times litter sample, 6 times Mini Winkler, 2 times Winkler sample, 2 times baiting.

Elevations: collected from 5 - 1470 meters, 512 meters average

Collect Date Range: collected between 1935-08-01 and 2020-02-16

Type specimens:

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