Proceratium burundense de Andrade, 2003

Hita Garcia, Francisco, Hawkes, Peter G. & Alpert, Gary D., 2014, Taxonomy of the ant genus Proceratium Roger (Hymenoptera, Formicidae) in the Afrotropical region with a revision of the P. arnoldi clade and description of four new species, ZooKeys 447, pp. 47-86 : 57

Taxon classification Animalia Hymenoptera Formicidae

Proceratium burundense de Andrade, 2003 Figs 1C, 2B, 4C, 5A, 5D, 10A, 10B, 10C, 18

Proceratium burundense de Andrade, in Baroni Urbani and de Andrade 2003: 294.

Type material.

Holotype, pinned worker, BURUNDI, Bujumbura, 4.III.77, (A. Dejean) (BMNH: CASENT0902427).

Diagnosis.

Proceratium burundense is easily distinguishable from the other Afrotropical species of the Proceratium 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.

Worker measurements

(N=1). TL 3.44; EL 0.06; SL 0.54; HL 0.79; HLM 0.90; HW 0.72; WL 1.02; HFeL 0.59; HTiL 0.51; HBaL 0.39; PeL 0.32; PeW 0.39; DPeI 121; LT3 0.58; LS4 0.24; LT4 0.61; OI 8; CI 91; SI 0.68; IGR 0.39; ASI 106.

[Note: the singleton holotype was examined in BMNH, but not measured. The measurements presented above are the ones given by Baroni Urbani and de Andrade (2003) except for HLM, PeL, PeW and LT3, which were measured from the montage images of the specimen]

Worker description.

In full-face view head slightly longer than broad (CI 91), sides weakly convex, not broadening posteriorly, vertex flat to weakly convex. Clypeus medially reduced, its anterior margin subconvex to slightly triangular, only slightly protruding anteriorly, not surrounding the antennal sockets and not medially impressed, antennal socket with broad torulus. Frontal carinae relatively short and widely separated, not converging medially and strongly diverging posteriorly, partially covering antennal insertions; frontal carinae conspicuously raised on their anterior half, much less posteriorly. Eyes small (but larger than in remainder of group), consisting of nine well developed ommatidia (OI 8) and located on mid line of head. Mandibles elongate-triangular; masticatory margin of mandibles with four to five relatively small teeth/denticles, decreasing in size from larger apical tooth to very small basal denticle. Mesosoma clearly convex in profile and slightly longer than maximum head length including mandibles. Lower mesopleurae with well impressed sutures, no other sutures developed on lateral or dorsal mesosoma; mesopleurae moderately inflated posteriorly; propodeum in profile armed with small, pointed teeth, propodeal lobes well developed, lamellate, subtriangular and blunt; declivitous face of propodeum between teeth and lobes noticeably concave; in posterodorsal view sides of propodeum separated from declivitous face by margin connecting propodeal lobes and propodeal teeth. Legs slender and elongate; pro- and mesotibiae with pectinate spurs; calcar of strigil without basal spine. Petiolar node in profile high, blocky nodiform, anterior face of petiole relatively straight, anterior and posterior faces approximately parallel, dorsum of node flat to weakly convex; petiole in dorsal view around 1.2 times wider than long (DPeI 121), petiolar node in dorsal view clearly much broader than long; ventral process of petiole lamelliform and subrectangular with posteroventral corner strongly pointing ventrally, almost spiniform. In dorsal view abdominal segment III anteriorly broader than petiole; its sides diverging posteriorly; dorsum of abdominal tergum III with posteromedial, very conspicuous, semitransparent, flat bulla below the integument; abdominal sternite III anteromedially with a marked subtriangular projection. Constriction between abdominal segment III and IV conspicuously impressed. Abdominal segment IV strongly recurved (IGR 0.39), conspicuously rounded on its curvature, especially posteriorly, abdominal tergum IV only slightly longer than abdominal segment III (ASI 106); semitransparent bulla situated posteromedially on abdominal tergum IV; remaining abdominal tergites and sternites relatively inconspicuous and curved ventrally. Whole body covered with dense mat of relatively short, decumbent to suberect pubescence without any abundant, much longer, suberect to erect, long, fine, standing hairs. Mandibles longitudinally rugose; most of body irregularly foveolate and/or granulate, sculpture best developed on cephalic and mesosomal dorsum, less so remainder of body and especially weak on most of relatively shining abdominal tergum IV, abdominal tergum IV posteroventrally (shortly before abdominal tergum V) with irregularly rugose area; inflated, posterior part of mesopleura and declivitous face of propodeum also mostly unsculptured and relatively smooth and shining. Head, mesosoma, petiole and remaining abdominal segments brown; mandibles, antennae, and legs of lighter brown.

Distribution and ecology.

The species is only known from the type locality in Burundi (Fig. 18). Unfortunately, the label provides very little locality data. Bujumbura is the capital of Burundi, but it is unclear if Proceratium burundense was collected in an urban habitat or in the area surrounding of the city. Also, there is no natural history data available.

Taxonomic notes.

As noted above, the presence of a larger compound eye that consists of nine well developed ommatidia in the worker caste distinguishes Proceratium 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 Proceratium 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, Proceratium 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, Proceratium burundense , as well as Proceratium arnoldi and Proceratium lunatum , lack numerous long, fine standing hairs on top of a mat of short decumbent to subdecumbent pubescence while these hairs are present in Proceratium nilo , Proceratium sali , Proceratium carri and Proceratium sokoke . Furthermore, the ventral process of the petiole, which is subrectangular with the posteroventral corner strongly pointing ventrally, almost spiniform, in Proceratium burundense separates it clearly from Proceratium nilo , Proceratium sali , Proceratium lunatum and Proceratium sokoke that have a process without a posteroventral corner that is strongly projected ventrally. The shape of the ventral process in Proceratium arnoldi and Proceratium carri is closest to the one seen in Proceratium burundense but the latter species cannot be misidentified with Proceratium arnoldi and Proceratium carri based on the characters presented above (e.g. head shape, eye size, pilosity). Proceratium lunatum is likely the species morphologically closest to Proceratium 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 Proceratium lunatum vs. small but longer and clearly pointed in Proceratium burundense .

Variation.

Since Proceratium burundense is only known from the holotype, there is no information about intraspecific variation.