Proceratium lombokense

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Proceratium lombokense
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Proceratiinae
Tribe: Proceratiini
Genus: Proceratium
Species: P. lombokense
Binomial name
Proceratium lombokense
Emery, 1897

Proceratium lombokense P casent0903854.jpg

Proceratium lombokense D casent0903854.jpg

Specimen Label

Only known from the queen caste.

Identification

A member of the silaceum clade that differs from the other Oriental species, in the gyne, by the following combination of characters: TL = 4.90 mm (instead < 4.50 mm), frontal carinae very broad and petiole subrectangular. The unique gyne of Proceratium lombokense appears to be the second largest species of the silaceum clade in the Old World. Only Proceratium relictum from the Fiji Islands is larger than lombokense. relictum differs from lombokense mainly by the shape of the petiole which is flattened apically. The gyne of Proceratium sulawense (TL 4.32-4.34 mm) is the third largest species of the silaceum clade of the Old World. sulawense shares with lombokense the broad frontal carinae, the petiole subrectangular and a large value of CI (≥ 104). lombokense differs from sulawense mainly by the sculpture, much more superficial, and by the light colour, orange light brown instead of dark ferrugineous-brown.

Distribution

Known from Lombok Island, Indonesia.

Distribution based on Regional Taxon Lists

Indo-Australian Region: Indonesia (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.

  • lombokense. Proceratium lombokense Emery, 1897c: 593 (footnote) (q.) INDONESIA (Lombok I.). See also: Baroni Urbani & De Andrade, 2003b: 435.

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

Description

Queen

Baroni Urbani and de Andrade (2003) - Head slightly broader than long, with subparallel sides. Anterior clypeal border weakly concave and about as long as the antennal sockets. Frontal carinae far from each other and with broad lateral expansions. Lateral expansions of the frontal carinae diverging on the two anterior fourths, converging in the third fourth, subparallel and carinate only on the last fourth., Genal carina short, weakly impressed and corresponding to the external border of a deep, longitudinal sulcus. Eyes large, on the midline of the head and with hairs. Ocelli well developed. First funicular joint about as long as broad. Funicular joints 2-10 broader than long. Last funicular joint about as long as the sum of joints 7-10. Scapes reaching the anterior ocellus; proximal half of the scape about half narrower than the distal half. Mandibles subtriangular. Masticatory margin of the mandibles with 10 denticles followed by a relatively large, subapical tooth and a pointed apical tooth. Palp formula not well visible but probably 2,2.

Mesosoma robust. Mesonotum gently convex. Parapsidal furrows superficially impressed. Scutellum almost flat, about 1/3 broader than long. Metanotum with a small, flat, pointed spine. Propodeum with distinct basal and declivous faces laterally separated by a small, pointed denticle. Basal face of the propodeum shorter than the declivous face and dorso-medially declivous posteriorly. Propodeal lobes subround. Propodeal spiracle round and above mid height in lateral view.

Petiole about 1/3 broader than long. Petiolar node narrow in side view, with gently convex dorsum and slightly higher than the anterior part of the postpetiole. Anterior border of the petiole straight and anterolaterally carinate. Ventral process of the petiole broad, lamelliform, convex anteriorly and with a small spine gently pointing backwards. Postpetiole slightly longer than 1/2 of gastral tergite I. Postpetiolar sides diverging backwards. Postpetiolar sternite anteromedially with a marked subrectangular projection. Constriction between postpetiole and gastral segment I impressed. Gastral tergite I convex. Remaining gastral tergites and sternites curved ventrally.

Legs slender, 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 slightly shorter than hind tibiae. Pretarsal claws simple. Arolia absent.

Wings missing.

Sculpture. Body superficially shining and variably punctate. Head more opaque than the rest of the body and with additional, thin, irregular rugosities. Metapleurae longitudinally rugulose, the rugosities slightly thicker than on the head. Basal face and part of the declivous face of the propodeum with additional transversal, thin, rugosities. Petiole and postpetiole with superimposed small granulation.

Body covered by hairs of three types: (1) short, dense, subdecumbent on the head, on the on the mesosoma, on the petiole, on the postpetiole and on the gaster, decumbent on the scapes and on the legs, suberect and sparse on the funicular joints; (2) longer, thicker and sparser than hair type (1), erect or suberect on the whole body; (3) shorter than hairs of type (1), dense, decumbent and appressed on the funicular joints only. In addition the scapes bear sparse hairs, shorter than type (2), the funicular joints bear thick, appressed, short, sparse hairs.

Colour orange to light brown.

Measurements in mm and Indices: TL 4.90; HL 0.98; HW 1.02; EL 0.27; SL 0.65; WL 1.44; PeL 0.33; PeW 0.48; HFeL 0.87; HTiL 0.64; HBaL 0.58; LS4 0.60; LT4 1.14; CI 105.0; SI 66.3; IGR 0.53.

Type Material

Baroni Urbani and de Andrade (2003) - Type locality: Lombok Island, Indonesia. Type material holotype gyne labeled: "Lombok, Sapit 2000', April 1896, H Fruhstorfer, Typus, Proceratium lombokense, n. sp. Emery", in Museo Civico di Storia Naturale, Genoa, 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 435, queen described)