Carebara sangi

The type series was obtained from one of ten cheese bait traps (small plastic tubes with several entrances containing powdered cheese as bait) buried ca. 10 cm underground in a well-developed forest at ca. 435 m alt. The circumstantial evidence as well as its morphological features (depigmentation and flat body without eyes) suggest that Carebara sangi is a subterranean nester and forager. (Eguchi & Bui, 2007)

Identification
Originally described as part of a genus with this ant as its only species the genus was diagnosed, in part, as follows (Eguchi & Bui, 2007):

Distinguished from the other myrmicine known from the Indo-Chinese subregion by a combination of the following features: median clypeal seta well developed; posteromedian portion of clypeus narrowly inserted between frontal lobes; masticatory margin of mandible with 5 distinct teeth; antenna 11-segmented, with a 2-segmented club; eye completely absent.

Monomorphic myrmicine ants with the following combination of characteristics. Frontal lobe in full-face view only partially concealing the toruli, not extending posteriorly as a frontal carina; antennal scrobe absent; posteromedian portion of clypeus narrowly inserted between frontal lobes; median clypeal seta well developed; 1st paracarinal seta well developed; lateral portions of clypeus not forming a raised rim or shield wall in front of the antennal insertions; the position of anterior tentorial pit as in Fig. 4; mandible triangular, overlapping but not crossing over at full closure, with 5 distinct teeth on the masticatory margin but without any tooth/denticles on the basal margin; trulleum open; hypostoma with a conspicuous lateral tooth just mesal to each mandibular base; anterior margin of labrum broadly concave medially; palpal formula: maxillary 2 and labial 2; antenna 11-segmented, with a 2-segmented club (Fig. 6); the apical antennal segment elongated much more than the preapical segment; eye completely absent. Promesonotum low, in profile almost flat or very weakly convex dorsally, without conspicuous humerus; promesonotal suture completely absent dorsally; mesosoma in dorsal view constricted between promesonotum and propodeum; metanotal groove relatively shallowly impressed dorsally; propodeum unarmed but with a narrow cuticular rim on each posterolateral corner of the dorsum; the rim running downward and connecting with metapleural lobe; each meso and metasternum without a conspicuous process; metapleural lobes low and round; propodeal spiracle small, situated a little behind the midlength of the sides of propodeum; metapleural gland large. Fore basitarsus with a long and thick seta on the posteroinner margin (sbt in Fig. 8); meso and metatibial spur absent. Petiole pedunculate anteriorly and with a distinct node; the peduncle with a small anteroventral process; postpetiole much shorter than petiole, in dorsal view a little broader than petiolar node, narrowly attached to the anteriormost end of gaster. Abdominal tergite IV (= gastral tergite I) broadly overlapping the sternite IV on the ventral surface of abdomen; gastral shoulder present (gs in Fig. 9); sting poorly developed (st in Fig. 9). Body smooth to very weakly sculptured.

Distribution based on Regional Taxon Lists
Oriental Region: Vietnam.

Nomenclature

 *  sangi. Parvimyrma sangi Eguchi & Bui, 2007: 44, figs. 1-10 (w.) VIETNAM. Combination in Carebara: Fernández, 2010: 195.

Worker
Holotype: HL 0.37 mm, HW 0.26 mm, SL 0.21 mm, ML 0.42 mm, FL 0.19 mm, CI 71, SI 81, FI 71. Paratypes (n=4): HL 0.37 mm, HW 0.26–0.27 mm, SL 0.21 mm, ML 0.40–0.41 mm, FL 0.19–0.20 mm, CI 71–73, SI 78–79, FI 71–74.

Monomorphic myrmicine ants with the following combination of characteristics. Frontal lobe in full-face view only partially concealing the toruli, not extending posteriorly as a frontal carina; antennal scrobe absent; posteromedian portion of clypeus narrowly inserted between frontal lobes; median clypeal seta well developed; 1st paracarinal seta well developed; lateral portions of clypeus not forming a raised rim or shield wall in front of the antennal insertions; the position of anterior tentorial pit as in Fig. 4; mandible triangular, overlapping but not crossing over at full closure, with 5 distinct teeth on the masticatory margin but without any tooth/denticles on the basal margin; trulleum open; hypostoma with a conspicuous lateral tooth just mesal to each mandibular base; anterior margin of labrum broadly concave medially; palpal formula: maxillary 2 and labial 2; antenna 11-segmented, with a 2-segmented club (Fig. 6); the apical antennal segment elongated much more than the preapical segment; eye completely absent. Promesonotum low, in profile almost flat or very weakly convex dorsally, without conspicuous humerus; promesonotal suture completely absent dorsally; mesosoma in dorsal view constricted between promesonotum and propodeum; metanotal groove relatively shallowly impressed dorsally; propodeum unarmed but with a narrow cuticular rim on each posterolateral corner of the dorsum; the rim running downward and connecting with metapleural lobe; each meso and metasternum without a conspicuous process; metapleural lobes low and round; propodeal spiracle small, situated a little behind the midlength of the sides of propodeum; metapleural gland large. Fore basitarsus with a long and thick seta on the posteroinner margin (sbt in Fig. 8); meso and metatibial spur absent. Petiole pedunculate anteriorly and with a distinct node; the peduncle with a small anteroventral process; postpetiole much shorter than petiole, in dorsal view a little broader than petiolar node, narrowly attached to the anteriormost end of gaster. Abdominal tergite IV (= gastral tergite I) broadly overlapping the sternite IV on the ventral surface of abdomen; gastral shoulder present (gs in Fig. 9); sting poorly developed (st in Fig. 9). Body smooth to very weakly sculptured.

Type Material
Holotype worker: Tay Yen Tu N. P., 21°10’11”N, 106°43’06”E, 435 m alt., Bac Giang Prov., N. Vietnam, 28 May 2004 (K. Eguchi leg., colony Eg04-VN-138).

Paratypes: 42 pinned and 2 slide-mounted workers from the same colony as holotype [IEBR,, , , , ].