Proceratium ecuadoriense

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Proceratium ecuadoriense
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Proceratiinae
Tribe: Proceratiini
Genus: Proceratium
Species: P. ecuadoriense
Binomial name
Proceratium ecuadoriense
De Andrade, 2003

Known from a small number of specimens collected in Ecuador.

Identification

A member of the micrommatum clade appearing as the basal species of a small clade containing three additional species: Proceratium brasiliense, Proceratium catio and Proceratium colombicum. Differing from these three species by the following two worker characters: broader and lower propodeal tumulus and deeper integumental sculpture. Proceratium ecuadoriense can be easily distinguished from the other species of the micrommatum clade by the combination of characters given below in the description. (Baroni Urbani and de Andrade 2003)

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Ecuador (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

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.

Castes

Nomenclature

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

  • ecuadoriense. Proceratium ecuadoriense De Andrade, in Baroni Urbani & De Andrade, 2003b: 127, fig. 59 (w.) ECUADOR.

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

Description

Worker

Head longer than broad, slightly narrower than posteriorly. Vertex in full face view convex. Clypeus corresponding to a small triangular tooth between and slightly longer than the antennal socket. Antennal socket with broad torulus. Frontal carinae close to each other, not covering the antennal insertions. Frontal area behind the frontal carinae weakly convex. Lateral expansions of the frontal carinae relatively narrow, raised, subparallel. Genal carinae present, marked, prolonging towards the hypostomal bridge and bounding a superficially smooth gular area. A superficial sulcus is present between the genal carinae and the gular area. Eyes present, composed by a clearly convex facet below the head midline. Scapes thicker in the distal half and far short of the vertexal margin. First funicular joint 1/3 longer than broad. Funicular joints 2-10 broader than long. Last funicular joint as long as the sum of joints 6-10. Mandibles with 3-4 denticles before the apical tooth. Palp formula apparently 3,2.

Mesosoma slightly convex in profile. Promesonotal and propodeal sutures absent. Promesopleural and mesometapleural sutures impressed on the ventral half only. Basal face of the propodeum with a broad, short, tumulus medially; area behind the propodeal tumulus with a superficial transversal sulcus. Declivous face of the propodeum flat; its sides with a superficial margin. Propodeal lobes ventrally truncate and dorsally with a subround, narrow crenulate margin. Propodeal spiracles small and tumuliform.

Petiole slightly longer than broad, subparallel in the anterior fourth and convex posteriorly in dorsal view. Anterior border of the petiole entirely carinate and only angulate on each side. Ventral process lamelliform and triangular. Postpetiole more than 1/2 of the length of the gastral tergite I (LT4), with convex sides in dorsal view. Postpetiolar sternite anteromedially with a marked subtriangular projection. Posterior half of the postpetiolar sternite slightly convex. Constriction between postpetiole and gastral segment I deeply impressed. Gastral tergite 1 convex dorsally and round on the curvature. Gastral sternite I (LS4) very short medially. Sides of gastral sternite I slightly protruding anteriorly, obtuse or round and carinate. Remaining gastral tergites and sternites curved ventrally.

Legs slightly elongate. Mid tibiae without spur. Spurs of fore legs without basal spine. Fore basitarsi longer than the mid ones. Hind basitarsi about 1/5 shorter than hind tibiae. Second tarsomere of mid and hind legs longer than third and fourth tarsomeres and slightly shorter than pretarsus. Pretarsal claws simple. Arolia very small.

Sculpture. Head, mesosoma, petiole and postpetiole irregularly reticulate-foveolate and granulate, these sculptures less marked on the propodeal tumulus. The granules raised as small peaks on the petiole and postpetiole. Gaster densely granulate. Legs and antennae superficially granulate.

Body covered by hairs of three main types: (1) short, dense, subdecumbent on the whole body, sparse and erect on the funicular joints; (2) long, suberect and relatively dense on the whole body, absent from the tumulus of the basal face of the propodeum and on the antennae; (3) shorter than hair type (I), dense, subdecumbent and appressed on the funicular joints only. In addition the funicular joints bear whitish, thick, appressed, short, sparse hairs, and the scapes with sparse hairs similar to type (2) but shorter.

Colour ferrugineous with antennae and legs dark orange.

Measurements in mm and Indices: TL 3.21-3.62; HL 0.76-0.88; HW 0.69-0.80; EL 0.04-0.07; SL 0.49-0.55; WL 0.90-1.02; PeL 0.32-0.37; PeW 0.28-0.34; HFeL 0.61-0.70; HTiL 0.51-0.59; HBaL 0.38-0.45; LS4 0.15-0.18; LT4 0.68-0.79; CI 90.8-90.9; SI 62.1-64.5; IGR 0.22-0.23.

Type Material

Holotype worker from Ecuador labelled "Prov. Pichincha, S & J Peck, 1975, Tinalandia, 16 krn SE S. Domingo de los Colorados, Jun, 680 m", one paratype worker, same data as the holotype, both in Museum of Comparative Zoology.

Etymology

“Ecuadoriense" is a neologism indicating the provenance of this species from Ecuador.

Determination Clarifications

The identification keys by Brown (1980) and by Ward (1988) record the presence of "micrommatum" in Ecuador without explicitly referring to the material on which the record is based. All the Ecuadorian specimens of the micrommatum clade we saw belong unequivocally to ecuadoriense. In addition, our records for ecuadoriense are probably drawn on the same material as those resulting from the previous literature, at least in part. For this reason we tentatively list as synonyms of ecuadoriense these previous literature records.

References

  • Brown, W. L., Jr. 1980c [1979]. A remarkable new species of Proceratium, with dietary and other notes on the genus (Hymenoptera: Formicidae). Psyche (Camb.) 86: 337-346 (page 343, misidentification)
  • 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 127, fig. 59 worker described)
  • Ward, P. S. 1988. Mesic elements in the western Nearctic ant fauna: taxonomic and biological notes on Amblyopone, Proceratium, and Smithistruma (Hymenoptera: Formicidae). J. Kans. Entomol. Soc. 61: 102-124 (page 117, misidentification)