Proceratium burundense

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

Proceratium burundense P casent0902427.jpg

Proceratium burundense D casent0902427.jpg

Specimen Label

The species is only known from the type locality in Burundi. Unfortunately, the label provides very little locality data. Bujumbura is the capital of Burundi, but it is unclear if P. burundense was collected in an urban habitat or in the area surrounding of the city. Also, there is no natural history data available. (Hita Garcia, Hawkes and Alpert 2014)

Identification

Hita Garcia, Hawkes and Alpert (2014) - Proceratium burundense is easily distinguishable from the other Afrotropical species of the P. arnoldi clade by the following character combination: eyes larger, consisting of nine well developed ommatidia (OI 8); head slightly longer than broad (CI 91); maculae on vertexal angles of head well developed and conspicuous; mesopleurae moderately inflated posteriorly; petiolar node high nodiform, anteroposteriorly compressed, with anterior face relatively straight; petiole around 1.2 times wider than long (DPeI 121); ventral process of petiole lamelliform and subrectangular with posteroventral corner strongly pointing ventrally, almost spiniform; abdominal segment IV less than 1.1 times longer than abdominal segment III (ASI 106); head, mesosoma and petiole with mat of short decumbent to subdecumbent pubescence only, without any longer, fine suberect to erect hairs.

The presence of a larger compound eye that consists of nine well developed ommatidia in the worker caste distinguishes P. burundense (OI 8) from the other six species of the clade (OI 0–5), but also from most other known Proceratium species that have either no eyes, just one ommatidium or a few very weak, almost indistinguishable ommatidia only visible under higher magnifications (Baroni Urbani and de Andrade 2003). Baroni Urbani and de Andrade (2003) pointed out that they consider the eye of P. burundense as the only real compound eye found in workers. It should be mentioned that the known subergatoid intercastes have much larger compound eyes, as is the case in Proceratium toschii, but the presence of ocelli separates these immediately from normal workers, which lack ocelli. Not considering eye size, P. burundense shares a thicker head (CI 91) in full-face view with Proceratium nilo, Proceratium sali, Proceratium lunatum and Proceratium sokoke (CI 91–95), which contrasts with the thinner head seen in Proceratium arnoldi and Proceratium carri (CI 85–87). In addition, P. burundense, as well as P. arnoldi and P. lunatum, lack numerous long, fine standing hairs on top of a mat of short decumbent to subdecumbent pubescence while these hairs are present in P. nilo, P. sali, P. carri and P. sokoke. Furthermore, the ventral process of the petiole, which is subrectangular with the posteroventral corner strongly pointing ventrally, almost spiniform, in P. burundense separates it clearly from P. nilo, P. sali, P. lunatum and P. sokoke that have a process without a posteroventral corner that is strongly projected ventrally. The shape of the ventral process in P. arnoldi and P. carri is closest to the one seen in P. burundense but the latter species cannot be misidentified with P. arnoldi and P. carri based on the characters presented above (e.g. head shape, eye size, pilosity). Proceratium lunatum is likely the species morphologically closest to P. burundense since they share most characters except for eye size, the shape of the ventral process of the petiole, and the propodeal of the propodeal teeth (very small and blunt in P. lunatum vs. small but longer and clearly pointed in P. burundense.

Baroni Urbani and de Andrade (2003) - A member of the arnoldi clade. Differing from its sister species, Proceratium lunatum, in the worker, by the head more elongate and the scape longer and less robust, by the smaller and more superficial foveae over the whole integument and by the subtler sculpture on the gaster.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Burundi (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

Known only from the worker holotype.

Nomenclature

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

  • burundense. Proceratium burundense De Andrade, in Baroni Urbani & De Andrade, 2003b: 294, fig. 122 (w.) BURUNDI.

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, its sides weakly convex. Vertex in fill1 face view slightly convex, in full dorsal view flat and bearing on each side a round, semitransparent macula. Clypeus medially reduced, subconvex, between the and slightly longer than the antennal sockets. Anterior border of the clypeus minutely crenulate. Antennal socket with broad torulus. Frontal carinae far from each other, partially covering the antennal insertions. Frontal area concave posteriorly, the concavity connected to a longitudinal carina prolonging posteriorly. Lateral expansions of the frontal carinae broader than in lunatum, slightly raised, diverging on the two anterior thirds and slightly converging on the posterior third. Genal carinae marked, each carina corresponding to the external border of a deep sulcus. Eyes relatively large, composed by 9 ommatidia and placed on the midline of the head. First funicular joint slightly longer than broad. Funicular joints 2-10 broader than long. Last funicular joint about as long as the sum of joints 7-10. Scapes much shorter than the vertexal margin and gently thickening apically. External border of the mandibles concave. Masticatory margin of the mandibles with 3-4 denticles before the pointed apical tooth. Palp formula 3,2.

Mesosoma convex in profile and slightly longer than the maximum head length (mandibles included). Basal face of the propodeum gently declivous posteriorly. Area between the basal and declivous faces of the propodeum weakly concave. Basal and declivous faces of the propodeum separate laterally by a lamellaceous tooth. Sides of the declivous face of the propodeum with a broader and posteriorly obtuse lamella. Lower mesopleurae with well defined sutures, their posterior half strongly inflate and smooth. Propodeal spiracle round and above mid height in lateral view.

Petiolar node subconvex in profile, the dorsum of the node almost flat and bearing an irregular point postero-medially. Petiole in dorsal view with the sides diverging on the anterior fifth and convex posteriorly; its anterior border almost straight, carinate and laterally denticulate. Ventral process of the petiole lamelliform, subrectangular, the lamella strongly pointed posteriorly. Postpetiole anteriorly broader than the petiole; its sides gently convex. Postpetiolar dorsum with a postero-medial, semitransparent, flat bulla below the integument. Postpetiolar sternite anteromedially with a marked subtriangular projection. Postpetiolar stenlite strongly convex posteriorly in profile. Constriction between postpetiole and gaster impressed. Gastral tergite I convex on the curvature and with a postero-medial, semitransparent, flat bulla below the integument. Remaining gastral tergites and sternites curved ventrally.

Legs slender and more elongate than in lunatunz. All tibiae with a pectinate spur. Spurs of fore legs without basal spine. Fore basitarsi longer than the mid ones. Hind basitarsi about 1/4 shorter than hind tibiae. First tarsomere of hind legs subequal in size to the pretarsus. Pretarsal claws simple. Arolia present.

Sculpture. Head, mesosoma, petiole, postpetiole and gaster with small, irregular Foveae and granulate, the foveae smaller, shallower and sparser on the anterior third of the first gastral tergite. Caster with additional longitudinal, irregular, thin rugosities on the posterior two thirds. Legs punctate. Pilosity similar to lunatum but the hair type (1) suberect and subdecumbent and type (2) sparser.

Colour. Light fesrugineous-brown with lighter legs.

Measurernents in mrn and Indices: TL 3.44; HL 0.79; HW 0.72; EL 0.06; SL 0.54; WL 1.02; PeL 0.33; PeL 0.33; PeW 0.38; HFeL 0.59; HTiL 0.51; HBaL 0.39; LS4 0.24; LT4 0.61; CI 91.1; S168.3; IGR 0.39.

Holotype Specimen Labels

Type Material

Holotype worker (unique) from Burundi labelled: "Burundi, Bujumbura, 4.III.77, A. Dejean" in The Natural History Museum.

Etymology

"Burundense" is a neologism indicating the provenance from Burundi.

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 294, fig. 122 worker described)