Probolomyrmex Mayr, 1901

Eguchi, Katsuyuki, Viet, Bui Tuan & Yamane, Seiki, 2014, Generic Synopsis of the Formicidae of Vietnam (Insecta: Hymenoptera), Part II — Cerapachyinae, Aenictinae, Dorylinae, Leptanillinae, Amblyoponinae, Ponerinae, Ectatomminae and Proceratiinae, Zootaxa 3860 (1), pp. 1-46 : 42-43

Probolomyrmex Mayr, 1901

Taxonomy. The genus Probolomyrmex is assigned to the tribe Probolomyrmecini ( Bolton 2003) . It was revised by Taylor (1965), and more recently by Eguchi et al. (2006) for the Oriental species.

Morphology. Workers of Vietnamese species have the following features (see also Eguchi et al. 2006):

Worker monomorphic; body covered with extremely fine pubescence, without standing hairs; head in full-face view elongate, with anteriorly expanded shelf-like frontoclypeal region which overhangs mandibles; frontal lobes fused to each other and forming a vertical plate; antennal socket in full-face view fully exposed, located on frontoclypeal region; antennal scrobe absent; mandible small, elongate-triangular, with acute apical tooth followed by a series of small denticles; outer surface of mandible with several thick and short setae; antenna 12-segmented; eye absent; mesosoma in lateral view with a straight or very weakly sinuate dorsal outline; promesonotal suture and metanotal groove absent dorsally; mesopleuron not defined dorsally and posteriorly by suture or carina; posterior face of propodeum margined laterally with a carina which often forms a triangular propodeal spine; orifice of propodeal spiracle round; propodeal lobe low or moderately developed; waist consisting of a single segment (petiole); petiole without anterior peduncle; its outline in lateral view weakly convex anterodorsally, and vertical and straight or weakly notched posteriorly; subpetiolar process present, but variable in size and shape; gaster (consisting of abdominal segments III–VII) elongate; abdominal segment III never down-curved; abdominal sternite III with an U-shaped anteroventral ridge below helcium; girdling constriction between abdominal segments III and IV distinct; abdominal segment IV not or very weakly down-curved; its sternite in lateral view not reduced, trapezoidal; sting well developed.

Differentiation. The worker of Probolomyrmex is easily distinguished from that of the other genera of the poneromorph subfamilies by the combination of the following features: frontal lobes fused to each other and forming a vertical plate; antennal socket located in shelf-like frontoclypeal region that overhangs mandibles; mandible small, elongate-triangular, with acute apical tooth followed by a series of small denticles; outer surface of mandible with several thick and short setae; promesonotal suture and metanotal groove absent; gaster not downcurved; body covered with extremely fine pubescence, without standing hairs.

Vietnamese species (4 spp.).

P. dammermani Wheeler, 1928 . Au (Pu Mat).

P. longinodus Terayama et Ogata, 1988 . Au (Phu Quoc).

P. longiscapus Xu et Zeng, 2000 . Au (Cuc Phuong, Hon Ba).

P. vieti Eguchi, Yoshimura et Yamane, 2006 [= sp. eg-2]. Type locality: Cat Tien. Zry (Cat Tien).

Bionomics. Probolomyrmex spp. are found in rotting wood fragments and soil in well-developed forests.