Pheidole arachnion

Every Ant Tells a Story - And Scientists Explain Their Stories Here
Jump to navigation Jump to search
Pheidole arachnion
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Pheidole
Species: P. arachnion
Binomial name
Pheidole arachnion
Wilson, 2003

Pheidole arachnion inb0003622434 p 1 high.jpg

Pheidole arachnion inb0003622434 d 1 high.jpg

Specimen Labels


Workers, minors and majors, can be moderately abundant in Winkler or Berlese samples of forest floor litter but are rarely collected at baits. The lack of occurrence at baits suggests largely nocturnal foraging or foraging restricted to areas beneath litter or in rotten wood. One nest is known, from rotten wood on the forest floor. (Longino 2009)


See the description in the nomenclature section.

Keys including this Species


Distribution based on Regional Taxon Lists

Neotropical Region: Costa Rica (type locality), Nicaragua.

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb


This species occurs in wet forest habitats, from sea level to 1100m elevation.









The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • arachnion. Pheidole arachnion Wilson, 2003: 656, figs. (s.w.) COSTA RICA. Senior synonym of iradunca: Longino, 2009: 13.
  • iracunda. Pheidole iracunda Wilson, 2003: 712, figs. (s.w.) COSTA RICA. Junior synonym of arachnion: Longino, 2009: 13.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.


DIAGNOSIS A member of the tristis group characterized by the following combination of traits.

Major: dark reddish brown; sides of head covered by loose rugoreticulum (i.e. with large interspaces); humeri and postpetiolar nodes seen from above comulate (hom-shaped); lacking any trace of antennal scrobes.

Minor: propodeal spine reduced to an obtuse angle; body entirely smooth and shiny except for several carinulae on anterior half of dorsal surface of head, one of which loops on each side of the head in a semicircle from the end of the frontal lobe to the anterior clypeal border; a thin nuchal collar present.

Very similar to Pheidole iracunda, also of Costa Rica, but differing in details in the characters as listed and illustrated.

MEASUREMENTS (mm) Holotype major: HW 1.80, HL 1.98, SL 0.76, EL 0.18, PW 0.90. Paratype minor: HW 0.60, HL 0.62, SL 0.74, EL 0.10, PW 0.40.

COLOR Major: body and mandibles dark reddish brown, other appendages light reddish brown. Minor: body plain medium brown, appendages brownish yellow.

Pheidole arachnion Wilson 2003.jpg

Figure. Upper: holotype, major. Lower: paratype, minor. Scale bars = 1 mm.

Type Material

COSTA RICA: Rio Reventazon, 3-5 km east of Turrialba, Cartago, col. William L. Brown. Museum of Comparative Zoology

Longino (2009) - Pheidole iracunda Wilson, 2003: 712, figs. Holotype major worker and associated paratype minor worker: Costa Rica, Prov. Heredia, La Selva Biological Station (Cover, Moffett, Tobin) MCZ (examined).


Gr arachnion, cobweb, alluding to the loose rugoreticulum on the head of the major.