Carebara creolei 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 creolei Azorsa & Fisher sp. n.

Holotype.

(major worker), MAURITIUS, Brise Mt., Bambous, -20.3455, 57.75467, 200 m, rainforest, 27.v.2005, (B.L. Fisher et al.). Collection code BLF12072, (CASC: CASENT0060366). Paratypes: (6 major workers and 25 minor workers), with same data as holotype, 3 major workers (CASC: CASENT0060524, CASENT0060071, CASENT0060663), and 20 minor workers (BMNH: CASENT0060067, CASC: CASENT0060069, CASENT0060070, CASENT0060525, CASENT0060527, CASENT0060528, CASENT0060666, CASENT0060670, CASENT0060664, CASENT0060068, CASENT0060367, CASENT0060667, CASENT0060529, CASENT0060072, CASENT0060368, CASENT0060665, CASENT0060371, MCZ: CASENT0060668, MHNG: CASENT0060369, NHMB: CASENT0060370). 3 major workers and 4 minor workers from: Mauritius, Ile aux Aigrettes, -20.41883, 57.7305, 1 m, coastal scrub, 28.v.2005, (B.L. Fisher et al.), with collection code BLF12085, 3 major workers (BMNH: CASENT0060719, CASC: CASENT0060721, MCZ: CASENT0060720), and 4 minor workers (CASC: CASENT0060726, CASENT0060722, CASENT0060724, CASENT0060725). 2 minor workers from: Seychelles, St. Joseph Island, -5.437422, 53.363127, 22.vi.2003, (J. Gerlach), with collection code ANTC10036 (CASC: CASENT0189354) and ANTC10139 (CASC: CASENT0191438).

Diagnosis.

Antennae nine-segmented. Major: Head longer than wide, nearly subrectangular in full-face view, lateral margins straight and parallel; head longitudinally reticulate-rugose; mesosoma areolate-rugose; gaster smooth and shiny. Minor: Head sculpture areolate-rugose and mesosoma areolate-rugose.

Description of major workers.

Measurements (n=8): HL 0.45-0.53 (0.46); HW 0.36-0.39 (0.37); SL 0.21-0.22 (0.21); ML 0.10-0.11 (0.11); EL 0.02; EM 0.10-0.11 (0.10); HD 0.19-0.24 (0.24); WL 0.34-0.39 (0.35); PSL 0.06-0.07 (0.07); PW 0.21-0.23 (0.22); MFL 0.22-0.23 (0.22); MFW 0.06-0.07 (0.06); MTL 0.19-0.20 (0.20); PTL 0.15; PNL 0.07-0.08 (0.07); PTH 0.10-0.11 (0.10); PTW 0.09-0.11 (0.10); PPL 0.08-0.09 (0.08); PPNL 0.07-0.08 (0.07); PPH 0.09; PPW 0.09-0.11(0.10); GL 0.36-0.46 (0.40), GW 0.29-0.35 (0.29); CI 73-82 (80); MI 19-24 (24); SI 40-47 (46); MLI 56-62 (59); PPLI 53-60 (53); PPI 100; PSI 15-19 (19).

Head longer than wide (CI 73-82), in full-face view nearly subrectangular, about 1.3 times longer than wide. Posterior margin of head medially concave, posterolateral corners rounded, lateral margins nearly straight. Mandibles with five teeth. Anterior margin of clypeus with a concavity flanked by a pair of triangular teeth. Antennae with nine segments. Scapes short (HL 0.45-0.53, SL 0.21-0.22, SI 40-47). Ocelli absent. Eye present, consisting of one ommatidium (EL 0.02). Supraclypeal area extends posteriorly toward antennal insertions.

In profile view, promesonotum convex, metanotal groove deeply impressed. Propodeum about 1.5 times higher than long, dorsal face of propodeum nearly concave closer to posterodorsal corner, and convex closer anterodorsal corner, propodeum armed, posterodorsal corners each armed with a triangular tooth upwardly directed, declivity of propodeum concave with lamellate lateral margination on each side. Propodeal lobes short and triangular. Propodeal spiracle rounded and situated slightly 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 almost four times the diameter of the spiracle (PSL 0.06-0.07), and distance to declivity about 1.5 times the diameter of the spiracle. In dorsal view, promesonotum about as long as wide, anterior margin and sides rounded; sides of propodeum weakly concave in the middle.

Petiole longer than high (PTL 0.15, PTH 0.10-0.11) with relatively long peduncle, ventral face nearly flat but weakly convex medially. Combined outline of dorsal surface of peduncle and anterior face of node deeply concave medially, posterior face of node convex, anterodorsal corner rounded and posterodorsal corner convex, dorsum flat and declining posteriorly. Subpetiolar process produced as a small triangular denticle, slightly larger than propodeal spiracle. Postpetiolar node slightly convex, nearly flat, and lower than petiolar node. In dorsal view, postpetiolar node almost as wide as petiolar node (PTW 0.09-0.11, PPW 0.09-0.11), petiolar node wider than long (PTW 0.09-0.11, PNL 0.07-0.08), anterior and posterior margins of petiole straight, anterior margin of postpetiole straight, posterior margin rounded, sides of petiole rounded, sides of postpetiole convex.

Dorsal surface of mandibles, clypeus and supraclypeal area smooth and shiny, with scattered piligerous punctae on head and mandibles. Clypeus with a few poorly defined transverse rugae. Head reticulate-rugose in full-face view, with irregular longitudinal rugulae which do not reach posterior margin of head. Cephalic dorsum between frontal carinae with two longitudinal rugulae, extending from posterior clypeal margin to posterior quarter of head. In profile, posterolateral portion of cephalic dorsum areolate-rugose, except for smooth and shiny ventral area. Mesosoma areolate-rugose, except for middle sides of pronotum which are smooth and shiny. Petiole and ventral face of postpetiole areolate. In dorsal view, mesosoma areolate, petiole and postpetiole smooth and shiny, with scattered foveolae.

Lateral margins and posterior margin of head with short, sparse decumbent and appressed hairs. Scapes with appressed hairs. Outer margin of mandible with few decumbent hairs. Mesosoma with short decumbent hairs, and sparse long and erect hairs. Petiole, postpetiole and gaster with short decumbent to appressed hairs, and sparse long subdecumbent hairs. Tibia with decumbent hairs. Color yellowish ferruginous.

Description of minor workers.

Measurements (n=7): HL 0.31-0.33; HW 0.26-0.28; SL 0.18-0.20; ML 0.08-0.09; EL 0.01; EM 0.06-0.07; HD 0.14-0.21; WL 0.31-0.33; PSL 0.05-0.06; PW 0.17-0.19; MFL 0.17-0.21; MFW 0.04-0.05; MTL 0.13-0.15; PTL 0.10-0.11; PNL 0.06; PTH 0.07-0.09; PTW 0.07-0.08; PPL 0.06-0.07; PPNL 0.06; PPH 0.06-0.07; PPW 0.07; GL 0.22-0.33; GW 0.22-0.25; CI 79-88; MI 24-28; SI 58-63; MLI 61-81; PPLI 55-64; PPI 88-100; PSI 17-23.

Head a little longer than wide (CI 79-88), in full-face view nearly subquadrate, about 1.1 times longer than wide, narrowed anteriorly. Posterior margin of head nearly straight, posterolateral corners rounded, lateral margins slightly convex. Mandible with five teeth. Anterior margin of clypeus with a concavity flanked by a pair of triangular teeth. Antennae with nine segments. Scapes barely exceeding midpoint of head (HL 0.31-0.33, SL 0.18-0.20, SI 58-63). Eyes present, consisting of one ommatidium (EL 0.01). Supraclypeal area triangular and extends posteriorly toward antennal insertions.

In profile, promesonotum weakly convex, nearly flat, metanotal groove deeply impressed. Propodeum about 1.25 times higher than long, dorsal face of propodeum convex towards anterodorsal corner and medially concave, posterodorsal corners each armed with a triangular tooth, declivity of propodeum concave with lamellate lateral margination on each side. Propodeal lobes short and convex. Propodeal spiracle rounded 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 four times the diameter of the spiracle (PSL 0.05-0.06), and distance to declivity about half the diameter of the spiracle. In dorsal view, promesonotum about 1.08 times longer than wide, anterior margin and sides of promesonotum rounded, sides of propodeum weakly concave near posterodorsal corner.

Petiole longer than high (PTL 0.10-0.11, PTH 0.07-0.09) with a relatively long peduncle, ventral face nearly flat to weakly convex in the middle. Combined outline of dorsal surface of peduncle and anterior face of node deeply concave, posterior face of node slightly convex, anterodorsal corner rounded, posterodorsal corner convex, dorsum flat and declining posteriorly. Subpetiolar process produced as a small denticle, usually the same as the diameter of the propodeal spiracle. Postpetiolar node nearly flat and slightly lower than petiolar node. In dorsal view, petiolar node almost as broad as postpetiolar node (PTW 0.07-0.08, PPW 0.07), petiolar node slightly wider than long (PTW 0.0.7-0.0.8, PNL 0.06), anterior margin of petiole convex, posterior margin straight, anterior margin of postpetiole nearly straight and posterior margin slightly convex, sides of petiole and postpetiole convex to rounded.

Dorsal surface of mandibles smooth and shiny with scattered piligerous punctae on head and mandibles, clypeus finely sculptured. Head longitudinally areolate-rugose, malar space with longitudinal rugae. Mesosoma, petiole and ventral face of postpetiole areolate. In dorsal view, mesosoma areolate-rugose, petiole and postpetiole weakly areolate, and gaster smooth and shiny.

Lateral margins and posterior margin of head with short decumbent to appressed hairs. Scapes with abundant decumbent hairs. Outer margin of mandible with a few decumbent hairs. Mesosoma with long suberect hairs, and short subdecumbent hairs. Petiole and postpetiole with short appressed hairs and longer subdecumbent hairs. Tibia with decumbent hairs and gaster with abundant short subdecumbent hairs and sparse longer subdecumbent hairs. Color yellowish ferruginous.

Distribution and biology.

Carebara creolei is only known from Mauritius and Seychelles (Figure 68). It occurs in the coastal scrub, mangrove, mixed forest, and rainforest. The species was collected at different elevations, ranging from 1 m to 200 m, using Winkler traps. The individuals and colonies were found in sifted litter, leaf mold, rotten wood, under coconut husks on the ground, and under rootmats/litter on rocks. The distribution of this species on two distant islands is interesting given the presence of invasive species on these islands. It is possible that C. creolei has been introduced to these islands, but a review of described species from outside the region, notability SE Asia, did not turn up any possible candidates. Until futher evidence is obtained, it is best to consider this species as a new species and native to the region.

Comments.

Carebara creolei is endemic to Mauritius and Seychelles and is the only species where minor and major workers have a sculptured on heads and mesosoma. This species and C. grandidieri are the only two species with nine antennal segments. C. creolei does not have intermediates in the major worker subcaste.

Additional material examined.

MAURITIUS: Ile aux Aigrettes, -20.41883, 57.7305, 1 m, coastal scrub, 28.v.2005, (B.L. Fisher et al.); SEYCHELLES: St. Joseph Island, -5.437422, 53.363127, 22.vi.2003, (J. Gerlach); Conception Island, -4.66311, 55.36821, 65 m, mixed forest, 12-13.ii.2010, (B.L. Fisher et al.)