Proceratium tio

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Proceratium tio
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Proceratiinae
Tribe: Proceratiini
Genus: Proceratium
Species: P. tio
Binomial name
Proceratium tio
Snelling, R.R. & Cover, 1992

Proceratium tio P casent0281857.jpg

Proceratium tio D casent0281857.jpg

Specimen Label

The holotype was found in rainforest leaf litter.


A member of the stictum clade and to the goliath group, and differing from its sister species Proceratium goliath, in the worker, by the following combination of characters: propodeal teeth larger, ventral process of the petiole distinct and spiniform instead of at most shortly triangular.

Keys including this Species


Latitudinal Distribution Pattern

Latitudinal Range: 18.421308° to 15.5123738°.

Tropical South

Distribution based on Regional Taxon Lists

Neotropical Region: Guatemala, Mexico (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.


Explore-icon.png Explore Overview of Proceratium biology 
Very little is known about the biology of Proceratium ants. They nest in soil, rotten wood, under deep-set stones and, in a few cases, tree branches. For many species the nest consists of small rounded chambers hollowed out of soft rotten wood or in the soil. Toward the cooler limits of the range, particularly in North America, nests and foraging workers are found under deep set rocks instead of in rotten wood. The nest site is usually in forest shade, in old moist gardens, or similar habitats that are constantly moist. Some species of known to be egg predators of arthropods, especially of spiders.

Most Proceratium are relatively rare but this is not the full explanation for why they are not commonly collected. Colonies of most species are small. Based on anectdotal natural history information from a few species, it was once thought that most Proceratium would likely be found to have mature colonies that contain somewhere between 10 - 50 workers. Yet nests with more than 50, and in some cases up to 200, workers have been been reported. Besides small colonies, these ants also do not appear to forage in places where they are readily encountered.

Males and females are though to be produced in small numbers but we generally do not have enough data for colonies of any species to know what might be typical. Reproductive flights have been observered toward the end of the summer in some northern temperate areas. In these regions the nuptial flight occurs during the last half of August. Both sexes climb some distance from the nest entrance before taking flight. Workers too issue from the nest during the nuptial flight, as is often the case with otherwise cryptobiotic ants. ‎



The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • tio. Proceratium tio Snelling & Cover, 1992: 50, fig. 1 (w.) MEXICO (Veracruz).
    • Type-material: holotype worker.
    • Type-locality: Mexico: Veracruz, 6 mi. NE Catemaco, 1500 ft, 7.vii.1976, rainforest leaf litter (A. Newton).
    • Type-depository: MCZC.
    • Status as species: Bolton, 1995b: 367; Baroni Urbani & De Andrade, 2003b: 108 (redescription); Branstetter & Sáenz, 2012: 263.
    • Distribution: Guatemala, Mexico.

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



Baroni Urbani and de Andrade (2003) - Head slightly longer than broad, with sides gently diverging posteriorly. Vertex convex in full face view. Clypeus broad, convex, protruding anteriorly and surrounding the whole antennal insertions. Anteromedian margin of the clypeus with a notch. Frontal carinae very far from each other, strongly diverging posteriorly and not covering the antennal insertions. Lateral expansions of the frontal carinae broad and slightly raised. Frons concave medially. Genal carinae marked. Head ventrally with a pair of superficially impressed longitudinal sulci delimited externally by the genal carinae. Gular area deeply impressed. Eyes composed by a clear, convex facet, and placed slightly below the mid-line of the head. Scapes not reaching the vertexal border. First funicular joint about 1/5 longer than broad. Funicular joints 2-10 broader than long. Last funicular joint as long as the sum of joints 7-10. Mandibles with 3-4 denticles before the apical tooth. Palp formula 4,3.

Mesosoma convex in side view and slightly longer than the head (mandibles included). Promesonotal and propodeal sutures very weakly impressed. Promesopleural and meso-metapleural sutures impressed on the ventral half only. Basal face of the propodeum declivous posteriorly. Declivous face of the propodeum flat; sides of the declivous face carinate. Each side between the basal and declivous faces of the propodeum separate by a broad, subround, carinate tooth. Propodeal lobes subtruncate and apically convex. Propodeal spiracle tumuliform and placed over mid height in lateral view.

Petiole slightly longer than broad, with the sides diverging on the anterior third and convex posteriorly in dorsal view. Anterior border of the petiole gently concave and strongly carinate. Ventral process of the petiole spiniform. Postpetiole slightly shorter than gastral tergite I (LT4), with a broad tumulus close to the center of the posterior border in side view. Postpetiolar sternite anteromedially with a marked subtriangular projection. Posterior half of the postpetiolar sternite convex. Constriction between postpetiole and gastral segment I impressed. Gastral tergite I strongly convex. Remaining gastral tergites and sternites slightly curved ventrally.

Legs slender. All tibiae with a pectinate spur. Spurs of fore legs with a basal spine. Fore basitarsi slightly longer than the mid ones. Hind basitarsi about 1/5 shorter than hind tibiae. Second tarsomere of mid and hind legs longer than each, third and fourth tarsomeres, and slightly shorter than pretarsus. Pretarsal claws simple. Arolia present but small.

Sculpture. Head, mesosoma, petiole and postpetiole irregularly foveolate-punctate. Caster smooth and with sparse, minute piligerous punctures. Legs with dense piligerous punctures.

Body covered by hairs of three main types: (1) short, dense, subdecumbent on the whole body, suberect and sparse on the funicular joints; (2) long, suberect or subdecumbent, relatively dense on the whole body, absent on the scapes and funicular joints; (3) shorter than hair type (1), dense and decumbent on the funicular joints only. In addition, the funicular joints bear thick, appressed, short, sparse hairs and the scapes sparse, subdecumbent hairs slightly shorter than hair type (2).

Colour brownish-red, antennae and legs lighter.

Measurements in mm and Indices (specimen from CPCC): TL 5.30; HL 1.25; HW 1.17; EL 0.08; SL 0.87; WL 1.52; PeL 0.60; PeW 0.54; HFeL 1.16; HTiL 0.94; HBaL 0.74; LS4 0.14; LT4 0.92; CI 93.6; SI 70.2; IGR 0.15.

Type Material

Baroni Urbani and de Andrade (2003) - Type locality: Veracruz, Mexico. Type material: a worker labelled: "Mex: Vera Cruz, 6 mi NE Catemaco, VII.7.1976, elev. 1500', A. Newton, Berl. Rainforest leaf litter, Holotype", in Museum of Comparative Zoology, examined.


  • Baroni Urbani, C., de Andrade, M.L. 2003. The ant genus Proceratium in the extant and fossil record (Hymenoptera: Formicidae). Museo Regionale di Scienze Naturali, Monografie, 36, 1–492. (page 108, fig. 51 worker described)
  • Snelling, R. R.; Cover, S. P. 1992. Description of a new Proceratium from Mexico (Hymenoptera: Formicidae). Psyche (Camb.) 99: 49-53 (page 50, fig. 1 worker described)

References based on Global Ant Biodiversity Informatics

  • Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology
  • Longino J. T. L., and M. G. Branstetter. 2018. The truncated bell: an enigmatic but pervasive elevational diversity pattern in Middle American ants. Ecography 41: 1-12.
  • Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133