Carebara demeter 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 demeter Azorsa & Fisher sp. n.

Holotype.

(major worker), MADAGASCAR, Antsiranana , Réserve Spéciale Manongarivo, 14.5 km 220° SW Antanambao, -13.99833, 48.42833, 1175 m, montane rainforest, 20.x.1998, (B.L. Fisher). Collection code BLF01938, (CASC: CASENT0906155). Paratypes: (10 major worker and 9 minor workers), with same data as holotype, 10 major workers (BMNH: CASENT0192622, CASC: CASENT0248445, CASENT0248446, CASENT0248447, CASENT0248448, CASENT0248449, CASENT0248450, MCZ: CASENT0248451, MHNG: CASENT0248452, NHMB: CASENT0248453), and 9 minor workers (BMNH: CASENT0127683, CASC: CASENT0127688, CASENT0192568, CASENT0248454, CASENT0248455, CASENT0248456, CASENT0248457, CASENT0248458, MCZ: CASENT0248459).

Diagnosis.

Antennae ten-segmented. Major: Head longer than wide, nearly subrectangular in full-face view, lateral margins straight and parallel, head with longitudinal and irregular rugae, reticulate-rugose close to posterior margin of head; petiole triangular in profile view, combined outline of dorsal surface of peduncle and anterior face of node almost straight, ventral face medially convex, subpetiolar process present. Minor: Head longer than wide, slightly narrowed anteriorly, lateral margins weakly convex; dorsum of promesonotum and anterodorsal corner of propodeum at the same height, posterodorsal corner of propodeum each armed with a small triangular, angulate tooth; combined outline of dorsal surface of peduncle and anterior face of node weakly concave in the middle, posterior face slightly convex; gaster with abundant subdecumbent hairs.

Description of major workers.

Measurements (n=12): HL 0.53-0.64 (0.62); HW 0.43-0.50 (0.47); SL 0.24-0.25 (0.25); ML 0.10-0.14 (0.13); EL 0.02-0.03 (0.02); EM 0.14-0.17 (0.17); HD 0.28-0.37 (0.35); WL 0.48-0.58 (0.53); PSL 0.04-0.06 (0.06); PW 0.28-0.35 (0.33); MFL 0.26-0.31 (0.29); MFW 0.07-0.08 (0.08); MTL 0.20-0.23 (0.23); PTL 0.17-0.20 (0.20); PNL 0.08-0.10 (0.09); PTH 0.14-0.17 (0.15); PTW 0.12-0.14 (0.14); PPL 0.08-0.14 (0.12); PPNL 0.10-0.13 (0.11); PPH 0.10-0.14 (0.12); PPW 0.16-0.18 (0.18); GL 0.47-0.60 (0.49); GW 0.34-0.45 (0.42); CI 74-81 (76); MI 17-22 (21); SI 39-45 (40), MLI 60-70 (62); PPLI 44-74 (60); PPI 129-150 (129); PSI 9-14 (13).

Head longer than wide (CI 74-81), in full-face view nearly subrectangular, about 1.3 times longer than wide. Posterior margin of head slightly concave in the middle, posterolateral corners rounded, lateral margins straight. Mandibles with five teeth. Anterior margin of clypeus nearly straight, laterally convex. Antennae with ten segments. Scapes short (HL 0.53-0.64, SL 0.24-0.25, SI 39-45). Eyes present, consisting of two or three ommatidia (EL 0.02-0.03). Supraclypeal area triangular and appears as a short longitudinal depression, surpassing frontal carinae.

In profile, posterolateral corner of head with (medium and larger major workers) or without (smaller major workers) a small, obtuse tooth resembling a horn. Promesonotum high and strongly convex, metanotal groove deeply impressed. Propodeum about 1.6 times higher than long, dorsal face of propodeum slightly convex, nearly flat, declining posteriorly, posterodorsal corners of propodeum each armed with a small triangular tooth, declivity of propodeum concave, nearly flat, with thin lateral laminae. Propodeal lobes triangular. Propodeal spiracle rounded and situated above mid-height of sclerite by about half the diameter of the spiracle, and beyond mid-length of sclerite by about 1.5 times the diameter of the spiracle, distance from propodeal spiracle to posterodorsal corner of propodeum about twice the diameter of the spiracle (PSL 0.04-0.06), and distance to declivity same as the diameter of the spiracle. In dorsal view, promesonotum about as long as wide, anterior margin and sides rounded; sides of propodeum straight.

Petiole slightly longer than high (PTL 0.17-0.20, PTH 0.14-0.17) with short peduncle, ventral face medially convex. Combined outline of dorsal surface of peduncle and anterior face of node nearly straight, posterior face of node vertical and slightly concave, anterodorsal corner convex, posterodorsal corner rounded, dorsum convex. Subpetiolar process produced as denticle, slightly larger than the diameter of the propodeal spiracle. Postpetiolar node convex and lower than petiolar node. In dorsal view, petiolar node not as wide as postpetiolar node (PTW 0.12-0.14, PPW 0.16-0.18), petiolar node wider than long (PTW 0.12-0.14, PNL 0.08-0.10), anterior and posterior margins of petiole and postpetiole nearly straight, sides rounded in petiole and postpetiole.

Dorsal surface of mandibles, clypeus, supraclypeal area, and median area of head smooth and shiny; scattered piligerous punctae on mandibles and head. Head with longitudinal and irregular rugae and reticulate-rugose near the posterior margin. In profile, posterolateral portion of cephalic dorsum smooth and shiny. Mesosoma smooth and shiny, except for katepisternum (areolate), metapleuron (longitudinally and parallel areolate rugose), and propodeal lobes (areolate-rugose). Petiole and ventral face of postpetiole areolate-rugose. In dorsal view, mesosoma, petiole, postpetiole and gaster smooth and shiny, declivity of propodeum, anterior and posterior face of petiole finely areolate.

Lateral margins and posterior margin of head with short suberect hairs, short appressed hairs below eye level. Scapes with appressed hairs. Outer margin of mandible with decumbent to appressed hairs. Mesosoma with long and short suberect hairs. Petiole and postpetiole with short decumbent hairs and long subdecumbent hairs. Tibia with decumbent hairs. Gaster with abundant decumbent hairs, and longer suberect hairs. Color yellowish ferruginous.

Description of minor workers.

Measurements (n=6): HL 0.34-0.37; HW 0.29-0.32; SL 0.20-0.23; ML 0.09-0.11; EL 0.01; EM 0.10-0.11; HD 0.21-0.23; WL 0.35-0.39; PSL 0.02-0.04; PW 0.18-0.21; MFL 0.21-0.24, MFW 0.05-0.06, MTL 0.14-0.17, PTL 0.12-0.14; PNL 0.06-0.07; PTH 0.10-0.11; PTW 0.08-0.09; PPL 0.08-0.09; PPNL 0.07-0.08; PPH 0.07-0.08; PPW 0.11-0.12; GL 0.30-0.40, GW 0.24-0.28, CI 85- 89; MI 24-31; SI 59-64, MLI 72-77, PPLI 57-67, PPI 133-138, PSI 6-13.

Head longer than wide (CI 85-89), in full-face view nearly subrectangular, about 1.2 times longer than wide, and slightly narrowed anteriorly. Posterior margin of head nearly straight to slightly concave in the middle, posterolateral corners strongly convex, lateral margins slightly convex. Mandibles with five teeth. Anterior margin of clypeus nearly straight medially and laterally convex. Antennae with ten segments. Scape fails to reach the posterior margin of head (HL 0.34-0.37, SL 0.20-0.23, SI 59-64). Eye present, consisting of two ommatidia (EL 0.01). Supraclypeal area almost triangular and not well defined.

In profile view, promesonotum convex, metanotal groove deeply impressed. Propodeum about 1.3 times higher than long, dorsal face of propodeum nearly flat, declining posteriorly, anterodorsal corner convex, posterodorsal corners each armed with a small angulate tooth, declivity of propodeum slightly concave with thin lateral laminae which extend from posterodorsal corner of propodeum to propodeal lobe. Propodeal lobes triangular. Propodeal spiracle nearly oval and situated above mid-height of sclerite, and beyond mid-length of sclerite by about the diameter of the spiracle; distance from propodeal spiracle to posterodorsal corner of propodeum about 2.5 times the diameter of the spiracle (PSL 0.02-0.04), and distance to declivity about 1.4 times the diameter of the spiracle. In dorsal view, promesonotum slightly longer than wide (about 1.13 times longer than wide), anterior margin and sides weakly rounded; sides of propodeum weakly convex.

Petiole slightly longer than high (PTL 0.12-0.14, PTH 0.10-0.11) with short peduncle, ventral face medially convex. Combined outline of dorsal surface of peduncle and anterior face of node weakly concave in the middle, posterior face of node vertical and nearly straight, anterodorsal corner convex, posterodorsal corner rounded, dorsum rounded. Subpetiolar process produced as denticle, slightly larger than the diameter of the propodeal spiracle. Postpetiolar node rounded and lower than petiolar node. In dorsal view, postpetiolar node wider than petiolar node (PPW 0.11-0.12, PTW 0.08-0.09), petiolar node wider than long (PNL 0.06-0.07, PTW 0.08-0.09), anterior and posterior margins of petiole slightly convex, anterior and posterior margin of postpetiole straight, sides of petiole and postpetiole rounded.

Dorsal surface of head, mandibles and clypeus smooth and shiny, with scattered piligerous punctae on head and mandibles, except in central longitudinal area, malar area with short longitudinal rugae. Mesosoma smooth and shiny, except for katepisternum (areolate), and metapleuron (finely areolate-rugose). Petiole and ventral face of postpetiole areolate. In dorsal view, mesosoma, petiole, postpetiole, and gaster smooth and shiny.

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

Distribution and biology.

Carebara demeter is known only from northwestern Madagascar (Figure 68), in montane rainforest with an elevation of 1175 m. It was collected using Winkler traps, and individuals were found in leaf litter, leaf mold and rotten wood.

Comments.

Carebara demeter is endemic to the northwest of Madagascar. It can be confused with C. tana due to the form of the head. However, C. demeter has irregular longitudinal rugae and is rugoreticulate near the posterior margin of the head, while the frontal area is smooth and shiny in C. tana . The petiolar node of C. tana is thicker than C. demeter . The anterior margin of the petiole is nearly straight in C. demeter , but slightly concave in C. tana . The anteroventral corner of the petiole has a well-developed triangular tooth in C. demeter , and a small angulate triangular tooth in C. tana . The anterodorsal corner of the petiole is convex in C. tana , but rounded in C. demeter . The posterodorsal corner is convex in C. demeter , but slightly concave in C. tana . Only two additional species were recorded in this area: C. grandidieri , and C. jajoby .

C. demeter does not have intermediates in the major worker subcaste.