Proceratium diplopyx

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Proceratium diplopyx
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Proceratiinae
Tribe: Proceratiini
Genus: Proceratium
Species: P. diplopyx
Binomial name
Proceratium diplopyx
Brown, 1980

Proceratium diplopyx casent0003306 profile 1.jpg

Proceratium diplopyx casent0003306 dorsal 1.jpg

Specimen labels

Specimens have been collected from rainforest habitats.

Identification

Differing from all the species of the stictum clade by the gastral tergite I greatly hypertrophied posteriorly.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Malagasy Region: Madagascar (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

Worker

Nomenclature

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

  • diplopyx. Proceratium diplopyx Brown, 1980b: 337, figs. 1, 2 (w.) MADAGASCAR. See also: Baroni Urbani & De Andrade, 2003b: 71.

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) - P. diplopyx is the most distinctive species of the stictum clade and of the whole genus for the shape of the gastral tergite I. Brown (1980) suggested to consider diplopyx as representing a species group of its own. In spite of the bizarre gastral morphology, however, Brown (1. c.) stressed the affinities of diplopyx with his sticturn group. In our analysis, diplopyx appears as a member of the stictum clade with which it shares synapomorphically the basal spine on the protibial spur. If, on one hand, considering the diplopyx grotesque gastral shape worthy of a separate group could be considered a matter of taste, on the other hand, its resolved phylogenetic position within the stictum clade represents an obstacle to this course of action.

Description

Worker

Baroni Urbani and de Andrade (2003) - Head longer than broad with sides gently converging posteriorly. Vertex weakly convex in full face view and flat in dorsal view. Clypeus broad, convex, protruding anteriorly and surrounding the whole antennal insertions. Anteromedian margin of the clypeus with a very superficial notch. Frontal carinae apart each other, subparallel and not covering the antennal insertions. Lateral expansions of the frontal carinae narrow and low. Frons medially concave. Genal carina marked. Gular area gently impressed. Eyes present, with a single convex facet placed below the mid line of the head. First funicular joint longer than broad. Funicular joints 2-10 slightly longer than broad. Scapes reaching the vertexal margin and gently thickening apically. Masticatory margin of the mandibles with 3 denticles before the pointed apical tooth. Palp formula 4,3.

Mesosoma slightly longer than the head (mandibles included). Promesonotal and propodeal sutures absent. Promesopleural and mesometapleural sutures more impressed ventrally. Basal face of the propodeurn convex. Each side of the propodeurn between basal and declivous face with a pointed tooth. Propodeal lobes with a small, triangular dorsal tooth. Propodeal spiracle tumuliform.

Petiole 1/5 longer than broad. Petiole in dorsal view with the sides diverging on the anterior third and convex on the two posterior thirds. Anterior border of the petiole concave and carinate, the carina denticulate on each side. Ventral process of the petiole small and obtuse. Postpetiole about half of the length of the gastral tergite 1. Postpetiolar dorsum with a broad tumulus on the middle of the posterior half. Postpetiolar sternite anteromedially with a marked subtriangular projection followed by a short longitudinal superficial carina prolonging backwards. Posterior half of the postpetiolar sternite convex. Constriction between postpetiole and gaster impressed. Gastral tergite I deeply hypertrophied posteriorly. Remaining gastral tergites and sternites curved ventrally.

Legs slender, elongate. All tibiae with a pectinate spur. Spurs of fore legs with a basal spine. Fore basitarsi as long as the mid ones. Hind basitarsi about 0.8 of the length of the hind tibiae. Second tarsomere of inid and hind legs longer than third and fourth tarsoineres and about as long as the pretarsus. Pretarsal claws simple. Pretarsal arolium small.

Sculpture. Head irregularly reticulorugose; in addition to this sculpture, the frons, the vertex and the sides of the head very irregularly foveolate-granulate. Mesosoma, petiole and postpetioie very irregularly foveolate-granulate, the granulation raised as peaks. First gastral tergite smooth and with sparse granulation. Legs and scapes with dense punctures.

Body covered by hairs of three main types: (1) short, dense, subdecumbent on the whole body, erect and sparse on the funicular joints; (2) long, suberect or subdecumbent, sparse on the whole body but absent on the scapes and funicular joints; (3) shorter than the 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 hairs shorter than hair type (2).

Colour reddish-brown.

Measurements in mm and Indices: TL 5.86; HL 1.44; HW 1.24; EL 0.12; SL 1.12; WL 1.68; PeL 0.66; PeW 0.48; HFeL 1.52; HTiL 1.24; HBaL 1.00; LS4 0.19; LT4 1.32; CI 86.1; ST 77.8; IGR 0.14.

Holotype Specimen Labels

Type Material

Baroni Urbani and de Andrade (2003) - Type locality: Baie d'Antongil, Madagascar. Type material: holotype and paratype workers labelled: "Iaraka, 1000 m, Baie d'Antongi1, 26.XI.1969, Madagascar, Prov. Tamatave, J. M. Betsch", in Musee National d'Histoire Naturelle (holotype) and in Museum of Comparative Zoology (paratype), both examined.

References

  • 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 71, fig. 34, 35 worker described)
  • 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 337, figs. 1, 2 worker described)
  • Fisher, B. L. 1997a. Biogeography and ecology of the ant fauna of Madagascar (Hymenoptera: Formicidae). J. Nat. Hist. 31: 269-302 (see also)