Carebara raberi Azorsa & Fisher

Azorsa, Frank & Fisher, Brian L., 2018, Taxonomy of the ant genus Carebara Westwood (Formicidae, Myrmicinae) in the Malagasy Region, ZooKeys 767, pp. 1-149 : 1

Carebara raberi Azorsa & Fisher sp. n.

Holotype.

(major worker), MADAGASCAR, Mahajanga , Réserve Spéciale Marotandrano, Marotandrano 48.3 km S Mandritsara, -16.28322, 48.81443, 865 m, transition humid forest, 6-8.xii.2007, (B.L. Fisher et al.). Collection code BLF19156, (CASC: CASENT0140594). Paratypes: (14 major workers and 8 workers), with same data as holotype, 14 major workers (BMNH: CASENT0140593, CASC: CASENT0140693, CASENT0140579, CASENT0140576, CASENT0140596, CASENT0140577, CASENT0140587, CASENT0140589, CASENT0140583, CASENT0140580, CASENT0140582, MCZ: CASENT0140591, MHNG: CASENT0140585, NHMB: CASENT0140597), and 8 workers (BMNH: CASENT0140575, CASC: CASENT0140578, CASENT0140584, CASENT0140590, CASENT0140586, CASENT0140588, MCZ: CASENT0140592, MHNG: CASENT0140581).

Diagnosis.

Antennae ten-segmented. Major: Head nearly subrectangular, longer than wide, lateral margins nearly straight, posterior margin of head deeply concave; dorsum of propodeum nearly flat, slightly convex in the anterodorsal corner, posterodorsal corner with a pair of small triangular teeth; gaster with short decumbent hairs, and longer subdecumbent hairs. Minor: Head longer than wide, lateral margins slightly convex, posterior margin of head nearly straight; dorsum of propodeum flat and declining posteriorly, posterodorsal corner with a pair of small triangular teeth, gaster with short decumbent hairs and dispersed, longer subdecumbent hairs.

Description of major workers.

Measurements (n=16): HL 0.59-1.12 (0.77); HW 0.46-0.89 (0.57); SL 0.25-0.38 (0.28); ML 0.12-0.27 (0.15); EL 0.01-0.09 (0.01); EM 0.16-0.28 (0.21); HD 0.30-0.67 (0.39); WL 0.49-0.95 (0.60); PSL 0.06-0.12 (0.08); PW 0.28-0.52 (0.36); MFL 0.30-0.55 (0.37); MFW 0.08-0.13 (0.09); MTL 0.22-0.46 (0.29); PTL 0.17-0.39 (0.22); PNL 0.08-0.14 (0.09); PTH 0.15-0.26 (0.18); PTW 0.13-0.23 (0.18); PPL 0.11-0.21 (0.15); PPNL 0.10-0.19 (0.12); PPH 0.11-0.24 (0.16); PPW 0.17-0.29 (0.23); GL 0.45-1.05 (0.64); GW 0.36-0.79 (0.47); CI 74-81 (74); MI 18-25 (19); SI 34-46 (36); MLI 56-65 (65); PPLI 52-74 (68); PPI 117-138 (128); PSI 11-14 (14).

Head longer than wide (CI 74-81), in full-face view nearly subrectangular, about 1.3 times longer than wide. Posterior margin of head deeply concave, posterolateral corners well developed and nearly rounded, lateral margins slightly convex, nearly straight, slightly narrowed forward. Mandibles with six teeth. Anterior margin of clypeus straight, and laterally convex. Antennae with ten segments. Scapes short (HL 0.59-1.12, SL 0.25-0.38, SI 34-46). Ocelli present or absent. Eyes present, consisting of one ommatidium (EL 0.01-0.09). Supraclypeal area triangular and well defined.

In profile, promesonotum high and nearly rounded, metanotal groove deeply impressed. Propodeum lower than promesonotum, and about 1.7 times higher than long, dorsal face of propodeum flat and declining posteriorly, propodeum armed, posterodorsal corners each armed with a triangular tooth, anterodorsal corner convex, declivity weakly concave, with thin lateral laminae. Propodeal lobes triangular. Propodeal spiracle rounded and situated above mid-height of sclerite, and beyond mid-length of sclerite by about half the diameter of the spiracle, distance from propodeal spiracle to posterodorsal corner of propodeum about three times the diameter of the spiracle (PSL 0.06-0.12), and distance to declivity about twice the diameter of the spiracle. In dorsal view, promesonotum about as long as wide, anterior margin and sides rounded; sides of propodeum straight.

Petiole longer than high (PTL 0.17-0.39, PTH 0.15-0.26) and with relatively short peduncle, ventral face slightly convex. Combined outline of dorsal surface of peduncle and anterior face of node slightly concave, nearly straight, posterior face of node vertical and weakly convex, anterodorsal corner convex, posterodorsal corner rounded, dorsum convex. Subpetiolar process produced as a small denticle, almost the same as the diameter of the propodeal spiracle. Postpetiolar node nearly rounded and lower than petiolar node. In dorsal view, postpetiolar node wider than petiolar node (PTW 0.13-0.23, PPW 0.17-0.29) and petiolar node wider than long (PNL 0.08-0.14, PTW 0.13-0.23), anterior and posterior margins of petiole straight, anterior margin of postpetiole weakly concave, and weakly convex posterior margin, sides rounded in petiole and postpetiole.

Dorsal surface of mandibles, clypeus and frons smooth and shiny, with scattered piligerous punctae on head and mandibles. Head with longitudinal rugae directed toward posterior margin, rugoreticulate close to posterior margin of head. Posterolateral portion of cephalic dorsum smooth and shiny. Mesosoma smooth and shiny, except katepisternum, propodeum and metapleuron which are areolate. Petiole and ventral face of postpetiole areolate. In dorsal view, promesonotum, postpetiole and gaster smooth and shiny, propodeum and petiole areolate.

Lateral margins of head with short decumbent hairs and long suberect hairs, posterior margin with subdecumbent hairs. Scapes with appressed hairs. Outer margin of mandibles with sparse and short appressed hairs. Mesosoma with short subdecumbent hairs and long suberect hairs. Petiole with short decumbent hairs and long suberect hairs, postpetiole with short and long decumbent hairs. Tibia with appressed hairs. Gaster with short decumbent hairs and long subdecumbent hairs. Color yellowish ferruginous.

Description of minor workers.

Measurements (n=8): HL 0.38-0.41; HW 0.34-0.37; SL 0.23-0.25; ML 0.09-0.10; EL 0.01-0.02; EM 0.11-0.12; HD 0.24-0.25; WL 0.38-0.43; PSL 0.03-0.04; PW 0.19-0.22; MFL 0.23-0.26; MFW 0.05-0.06; MTL 0.18-0.21; PTL 0.14-0.16; PNL 0.07-0.08; PTH 0.10-0.12; PTW 0.09-0.10; PPL 0.08-0.09; PPNL 0.07-0.09; PPH 0.08-0.09; PPW 0.12-0.13; GL 0.33-0.40; GW 0.25-0.29, CI 87-90; MI 23-26; SI 59-63; MLI 68-74; PPLI 53-64; PPI 130-144; PSI 9-12.

Head longer than wide (CI 87-90), in full-face view nearly subquadrate, about 1.1 times longer than wide, slightly narrowed anteriorly. Posterior margin of head nearly straight, posterolateral corners rounded, lateral margins slightly convex. Mandibles with five teeth. Anterior margin of clypeus nearly straight, and laterally angulate. Antennae with ten segments. Scape fails to reach the posterior margin of head (HL 0.38-0.41, SL 0.23-0.25, SI 59-63). Eyes present, consisting of one ommatidium (EL 0.01-0.02). Supraclypeal area triangular but poorly defined.

In profile view, promesonotum weakly convex, metanotal groove deeply impressed. Propodeum about 1.5 times higher than long, dorsal face of propodeum flat and declining posteriorly, anterodorsal corner rounded, posterodorsal corners of propodeum each armed with a triangular tooth, declivity nearly flat, with thin lateral laminae. Propodeal lobes short and convex. Propodeal spiracle nearly oval and situated above mid-height of sclerite by about half the diameter of the spiracle, and beyond mid-length of sclerite by about the diameter of the spiracle, distance from propodeal spiracle to posterodorsal corner of propodeum about 1.5 times the diameter of the spiracle (PSL 0.03-0.04), and distance to declivity same as the diameter of the spiracle. In dorsal view, promesonotum about 1.3 times longer than wide, anterior margin rounded, sides convex, narrowed posteriorly; sides of propodeum straight.

Petiole longer than high (PTL 0.14-0.16, PTH 0.10-0.12) and with relatively short peduncle, ventral face slightly convex at center. Combined outline of dorsal surface of peduncle and anterior face of node concave, posterior face of node vertical and slightly convex, anterodorsal and posterodorsal corner rounded, dorsum convex. Subpetiolar process produced as a small denticle, slightly smaller than the diameter of the propodeal spiracle. Postpetiolar node nearly rounded and slightly lower than petiolar node. In dorsal view, postpetiolar node wider than petiolar node (PTW 0.09-0.10, PPW 0.12-0.13), and petiolar node wider than long (PNL 0.07-0.08, PTW 0.09-0.10), anterior and posterior margins of petiole weakly convex, anterior margin of postpetiole convex, and posterior margin concave, sides nearly rounded in petiole and postpetiole.

Dorsal surface of head, mandible and clypeus smooth and shiny with scattered piligerous punctae on head and mandibles. Gena and frontal lobes with short longitudinal rugae. Mesosoma smooth and shiny, except for katepisternum, propodeum and metapleuron which are areolate. Petiole and ventral face of postpetiole areolate. In dorsal view, promesonotum, postpetiole and gaster smooth and shiny, propodeum and petiole areolate.

Lateral margins of head with short decumbent hairs, posterior margin with suberect hairs. Scapes and outer margin of mandibles with decumbent hairs. Mesosoma with short and long suberect to subdecumbent hairs. Petiole and postpetiole with short decumbent hairs and longer subdecumbent hairs. Tibia with decumbent hairs. Gaster with short decumbent to appressed hairs, and long subdecumbent hairs. Color yellowish ferruginous.

Distribution and biology.

Carebara raberi is known from only one locality, in northeastern Madagascar, and only one locality (Figure 69). This species was found in the rainforest, at the transition between humid forest, and tropical dry forest, at 865 m, taken from sifted litter, rotten logs, and leaf mold. Individuals were collected using maxi-Winkler traps.

Comments.

Carebara raberi can be confused with C. sampi and C. lova but can be separated by the hair pilosity at the dorsum of the gaster, which is abundant in C. raberi , while in C. sampi and C. lova are fewer. C. raberi is known only from one locality in northeastern Madagascar, while C. sampi was recorded from south and southwestern Madagascar, and C. lova is known from the northwestern of Madagascar. C. raberi is the only species of Carebara recorded at this area.

C. raberi have three intermediates in the major worker subcaste (Figure 60). Posterolateral corners of the head of all intermediates are narrowed posteriorly. The posterior margin of the head is deeply concave in all of the intermediates. The eyes are reduced to one ommatidium in all intermediates. Ocelli are absent in intermediate 1, but present in intermediates 2 and 3 (one ocellus). Reduced flight sclerites are not present in any intermediate. The dorsum of the mesosoma is convex anteriorly and gradually slopes to the declivity in all intermediates. The propodeum is armed with a pair of small triangular teeth in all intermediates. The form of the petiole and postpetiole is the same among all intermediates. The sculpture in intermediate 1 and 3 is finely marked with parallel and longitudinal rugae, but the rugae are better defined in some specimens of intermediate 2. The frontal area is smooth and shiny in all intermediates. The pilosity on the head and body follows the same pattern in all intermediates.