Proceratium dayak

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

Proceratium dayak P casent0902419.jpg

Proceratium dayak D casent0902419.jpg

Specimen Label

Known only from the type specimen.

Identification

A Proceratium species belonging to the silaceum clade, resembling Proceratium austronesicum, but differing from it, in the worker, by the body with denser and stronger punctures, longer hind basitarsi, and narrower frontal carinae. (Baroni Urbani and de Andrade 2003)

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: Borneo (type locality), Indonesia, Malaysia.

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.

  • dayak. Proceratium dayak De Andrade, in Baroni Urbani & De Andrade, 2003b: 317, fig. 129 (w.) BORNEO.

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

Description

Worker

Head slightly longer than broad and with the sides gently diverging posteriorly. Vertex in full face view almost straight. Clypeus reduced and as long as the antennal sockets. Anterior border of the clypeus truncate. Frontal carinae not very broad, narrower than in austronesicum and not covering the antennal insertions. Lateral expansions of the frontal carinae narrow, weakly raised, diverging on the two anterior fourths, converging on the third fourth, subparallel and carinate only on the last fourth. Frontal area gently concave and with a superficial, thin longitudinal carina prolonging posteriorly. Head anterolaterally with a short, longitudinal carina. Genal carinae marked, each carina corresponding to the external border of a deep sulcus. Eyes absent. First funicular joint slightly longer than broad. Funicular joints 2- 10 broader than long. Last funicular joint as long as the sum of joints 6-10. Scapes short of the vertexal margin and gently thickening apically. Masticatory margin of the mandibles with 6-7 denticles before the pointed apical tooth. Palp formula 2,2.

Mesosoma in side view gently convex, as long as the maximum head length (mandibles included). Pronotal and propodeal sutures absent. Basal face of the propodeum declivous posteriorly. Area between the basal and declivous faces of the propodeum gently concave and with a small triangular tooth on each side. Declivous face of the propodeum sloping posteriorly. Sides of the declivous face of the propodeum carinate. Propodeal spiracle round and above mid height in lateral view.

Petiole subrectangular. Anterior border of the petiole straight and anterolaterally carinate. Ventral process of the petiole large, triangular. Postpetiole about 1/3 shorter than gastral tergite I. Postpetiole in dorsal view with its sides diverging anteriorly and convex posteriorly. Postpetiolar sternite anteromedially with a marked subtriangular projection, gently convex posteriorly in profile. Constriction between postpetiole and gaster impressed. Gastral tergite I convex on the curvature. Remaining gastral tergites and sternites curved ventrally.

Legs not very elongate. All tibiae with a pectinate 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 hind legs shorter than pretarsus. Pretarsal claws simple. Arolia absent.

Sculpture. Head, mesosoma, petiole and postpetiole densely punctate, the punctures larger on the dorsum of the mesosoma, of the petiole and of the postpetiole. Areas below the eyes and ventral part of the head reticulorugose. Basal face of the propodeum with additional, thin, irregular rugulae. Gaster and legs minutely punctate.

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

Colour. Dark ferrugineous with slightly lighter legs.

Measurements in mm and Indices: TL 2.90; HL 0.68; HW 0.65; EL absent; SL 0.44; WL 0.83; PeL 0.21; Pew 0.32; HFeL 0.49; HTiL 0.39; HBaL 0.32; LS4 0.31; LT4 0.63; CI 95.6; SI 64.7; IGR 0.49.

Type Material

Holotype worker from Sarawak labeled: "Sarawak, 4th Divis. G. Mulu Expd. X.1977, Camp 5, H. Vallack, soil core", in The Natural History Museum.

Etymology

Dayak is the name of one of the populations of Borneo. It is used as a name in apposition.

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 317, fig. 129 worker described)