Carebara sakamotoi

Known only from types that were found in soil about 30 cm in depth.

Identification
Terayama, Lin & Eguchi, (2012) - Among the Asian congeners, this species resembles Carebara capreola from Vietnam. Carebara capreola laeviceps, from southern China, and Carebara bihornata from mountain region of Yunnan Province in China in the occipital horns connected by a developed transverse ridge in major worker. However, it is separated from C. capreola and C. capreola laeviceps by the 9-segmented antennae (11-segmented in the latter two), and eyes absent in minor worker (small eyes present in the latter two), and from C. bihornata by the thick head capsule with convex anterior margin in profile and acute triangular occipital horns in major worker (thin with strait anterior margin of head and obtuse triangular occipital horns in bihornata), and head with convex anterior margin in profile and triangular petiolar node in minor worker (head with straight anterior margin and reversed U-shaped petiolar node in bihornata).

Distribution based on Regional Taxon Lists
Oriental Region: Taiwan.

Castes

 * Minor Worker

Nomenclature

 *  sakamotoi. Carebara sakamotoi Terayama, Lin & Eguchi, 2012: 2, figs. 4-7 (w.) TAIWAN.

Worker
Holotype. Major worker. Structure: Head long, 1.38 times as long as wide, with weakly convex sides and strongly concave posterior margin in full face view; occipital hom 0.06 mm long, forming acute triangle, and about 1.2 times as long as its basal width; horns connected by a developed transverse ridge; head in lateral view 1.80 times as long as high, with weakly convex dorsal and ventral margins.

Mandible with 5 teeth; apical tooth largest; basal smallest and dully angulated. Clypeus slightly produced medially, with straight anterior margin. Antenna with 9 segments, apical 2 segments forming a club; scape short, 2nd segment longer than wide, 3rd to 7th segments each wider than long, 8th segment 1.3 times as long as wide, terminal segment 3.2 times as long as wide; the ratio of apical 3 segments about 1: 2.5 : 8 in length from the base. Eye small, consisting of 4 facets, situated at anterior 113 of head.

Dorsal outline of pronotum moderately convex in profile, disc 0.35 mm in maximum width, 1.50 times as wide as long, with convex anterolateral comers in dorsal view. Mesonotal dorsum almost straight in profile. Matanotal groove distinct. Propodeum with straight dorsal outline and dully angulate posterolateral corner in profile.

Petiole longer than high, with reversed U-shaped node and straight ventral margin; in dorsal view, node 1.5 times as wide as long. Postpetiole lower than petiole, with convex anterior margin and straight dorsal margin; in dorsal view, 1.4 times as wide as long in dorsal view.

Gaster large; 0.55 mm in maximum width in dorsal view.

Sculpture: Frons of head microreticulate and scattered with shallow small punctures; frontal lobes with many thin longitudinal striae; vertex moderately microreticulate; maler space reticulate; genal area smooth. Mandible smooth and shining. Antennal scape weakly microreticulate and club microreticulate. Alitrunk largely smooth excepting mesopleura and lower half of side of propodeum that are microreticulate. Petiole and postpetiole microreticulate. Gaster smooth and shining. Coxae and trochanters microreticulate; femora and tibiae smooth.

Color: Head, alitrunk. petiole and postpetiole yellow; eye black; masticatory margin of mandible blackish brown; 1st gastral segment brownish yellow, 2nd to terminal segment yellow; legs yellow.

Measurements (mm): Holotype; Ill. 0.73; HW 0.53; SL 0.26; CI 72; SI 50; WL 0.65; PL 0.24; PH 0.18; DPW 0.15; PPL 0.15; PPH 0.13; PPW 0.18; TL 2.7. Paratype major worker; Ill. 0.70; HW 0.51; SL 0.25; CI 73; SI 49; WL 0.68; PL 0.23; PH 0.18; DPW 0.15; PPL 0.15; PPH 0.13; DPH 0.18; TL 2.8.

Paratype minor worker. Structure: Head 1.23 times as long as wide, with parallel sides and weakly concave posterior margin in full face view; posterolateral comer forming an dull angle, posterior margin carinate; head in lateral view 1.75 times as long as high, with weakly convex dorsal and ventral margins. Mandible with 5 teeth; apical 4 teeth acute; basal tooth small and blunt. Anterior margin of clypeus straight. Antenna with 9 segments, apical 2 segments forming a club; 3 rd to 7th segments each wider than long; 7th segment 0.5 times, 8th 1.1 times, and terminal segment 2.7 times as long as wide; the ratio of apical 3 segments 1 : 4: 13.6 in length from the base. Eye absent.

Pro- and mesonotal dorsum almost flat; pro notal disc 0.19 mm in maximum width, with round anterolateral corners in dorsal view; metanotal groove absent; propodeal disc very weakly convex, posterolateral comer rounded, not forming an angle in profile; propodeal teeth absent.

Petiole longer than high, with subtriangular node and straight ventral margin; tip of the node rounded. Postpetiole as long as wide, with straight dorsal margin in profile.

Gaster 0.24 mm in maximum width in dorsal view.

Sculpture: Frons and vertex of head weakly microreticulate; mandible smooth. Pronotum smooth; dorsa of mesonotum and propodeum smooth; mesopleuron microreticulate; lower half of side of propodeum microreticulate, upper half smooth and shining. Petiole weakly microreticulate, postpetiole microreticulate. Gaster very weakly microreticulate.

Color: Body yellow; masticatory margin of mandible blackish brown.

Measurements (mm): HL 0.34; HW 0.28; SL 0.19; CI 81; SI 68; WL 0.35; PL 0.13; PH 0.06; DPW 0.08; PPL 0.06; PPH 0.06; PPW 0.10; TL 1.1.

Etymology
The specific epithet is named after the collector of this species, Dr. H. Sakamoto.

References based on Global Ant Biodiversity Informatics

 * Terayama M., C. C. Lin, and K. Eguchi. 2012. Additions to knowledge of the ant fauna of Taiwan (Hymenoptera, Formicidae, Solenopsidini): genera Anillomyrma and Carebara. Jpn. J. Syst. Ent. 18(1): 1-6.