Crematogaster vieti

The types were collected in fragmented forest at an elevation of 1,100 m.

Identification
Hosoishi and Ogata (2016) - In the worker this species can be distinguished from all other members of the Crematogaster biroi group by the distinct compound eyes, generally smooth dorsal surface of head, petiole with subparallel sides in dorsal view, and erect setae on body tapering distally. This species is very similar to Crematogaster osakensis, but distinguished from it by the thick propodeal spines and petiole with subparallel sides.

Distribution based on Regional Taxon Lists
Oriental Region: Vietnam.

Nomenclature

 * . Crematogaster vieti Hosoishi & Ogata, 2016a: 601, figs. 122, 123 (w.) VIETNAM.
 * Type-material: holotype worker, 5 paratype workers.
 * Type-locality: Vietnam: Lao Cai, Sa Pa, Y Linh Ho (ca. 1100m.), 1.v.2002, Eg02-VN-225 (K. Eguchi); paratypes: 2 workers with same data, 3 workers with same data but Eg02-VN-215.
 * Type-depositories: IEHV (holotype); BMNH, CASC, KEPC, KUEC, TNHM (paratypes).
 * Distribution: Vietnam.

Worker
(n=9) HW 0.42–0.70; HL 0.45–0.64; CI 92–113; SL 0.37–0.51; SI 72–88; EL 0.10–0.16; PW 0.26–0.39; WL 0.54–0.75; PSL 0.07–0.14; PtL 0.17–0.24; PtW 0.13–0.20; PtH 0.12–0.18; PpL 0.11–0.16; PpW 0.15–0.21; PtHI 74–86; PtWI 77–88; PpWI 120–154; WI 95–111.

Workers weakly polymorphic in size. Head subquadratic in full-face view. Mandibles with four teeth arranged at an equal distance, apical and subapical teeth large, basal two teeth smaller. Anterior clypeal margin weakly convex in medial portion. Compound eyes distinctly projecting beyond lateral margins of head in full-face view. Scapes reaching posterolateral corners of head.

Pronotal collar with almost straight anterior margin in dorsal view, distinctly lower than pronotum in lateral view. Pronotal dorsum with distinct ridges laterally. Mesonotal dorsum with lateral ridges that irregularly extend posteriad to tips of propodeal spines. Pronotum and mesonotum in lateral view not clearly forming continuous dorsal outline. Metanotal groove in dorsal view transverse, almost straight in median portion, forming deep concavity that is laterally margined by lamellate ridges. Propodeal spiracles oval, situated at posterolateral corners of propodeum, apart from or touching metapleural gland bullae. Propodeal spines developed, longer than diameter of propodeal spiracles, in dorsal view directed posteriad.

Petiole in dorsal view with parallel sides and angulate shoulders anteriorly, longer than wide. Posterior portion of petiole with short process that is slightly higher than posterior margin of petiole disc in lateral view. Subpetiolar process developed as acute process. Postpetiole in lateral view with weakly convex dorsum, as high as petiole, in dorsal view as wide as petiole, globular, not bilobed. Subpostpetiolar process developed as acute process.

Integument essentially smooth and shining. Dorsal surface of head generally smooth and shining, but weakly with rugulae on surrounding region of antennal sockets. Mandibles with feeble rugulae and smooth interspaces. Clypeus generally smooth and shining, but with two distinct pairs of longitudinal rugulae; rugulae not extending to posterior clypeal margin. Anterolateral shoulders of pronotum with rugulae. Dorsal surface of pronotum with longitudinal rugulae. Lateral surface of pronotum smooth and shining. Mesopleura weakly sculptured, but relatively smooth on central areas. Rugula on higher portion of mesopleura extending to small pit of mesothoracic spiracles. Dorsal surface of propodeum with rugulae. Dorsal surface of petiole smooth and shining. Lateral surface of petiole weakly sculptured. Dorsal and lateral surfaces of postpetiole smooth and shining.

Standing pilosity sparse. Dorsal face of head with two to three pairs of erect and stout long setae, and short and decumbent setae sparsely. Clypeus with two pairs of long setae in anterior portion, one directed upward and the other downward. Anterior clypeal margin with one pair of long setae medially and some pairs of short setae laterally. Scapes with suberect to decumbent setae. Mesosoma with four pairs of long erect and stout setae (ps1PN, psaMN, pspMN, and ps1PS) that are much longer than other erect setae.

Posterolateral tubercles of petiole posteriorly with one pair of stout long setae. Postpetiole with four pairs of stout long setae on disc anterodorsally, anterolaterally and posteriorly. Fourth abdominal tergite with erect and stout setae sparsely, and short decumbent setae sparsely.

Body yellow. All flagellar segments yellow.

Intermediate (n=1): HW 0.68; HL 0.70; CI 97; SL 0.54; SI 79; EL 0.19; PW 0.47; WL 0.95; PSL 0.19; PtL 0.32; PtW 0.25; PtH 0.24; PpL 0.20; PpW 0.28; PtHI 75; PtWI 78; PpWI 140; WI 112.

With worker character conditions, except as follows. Vestigial lateral ocelli present. Mesonotum highly convex in lateral view. Mesonotal dorsum without lateral ridges. Pronotum not clearly forming same dorsal outline with mesonotum in lateral view, but posterior face forming oblique slope to metanotal groove. Propodeal spiracles touching metapleural gland bulla.

Petiole wth subparallel sides in dorsal view, tapering anteriorly. Subpetiolar process developed as blunt process.

Dorsal surface of pronotum smooth and shining. Dorsal surface of mesonotum with rugulae anteriorly and laterally. Mesopleura generally smooth, but oblique sulcus running from anterior areas. Anterodorsal surface of propodeum with rugulae reticulately.

Anterior clypeal margin with one single and one pair of long setae on median portion and some pairs of short setae laterally. Mesosoma with several pairs of long setae on promesonotum, one ps1PS. Posterolateral tubercles of petiole with two to three pairs of stout long setae posteriorly. Fourth abdominal tergite with suberect to decumbent setae abundantly.

MISC This species corresponds to sp. 36 of SKY (Eguchi et al., 2005) and sp. eg-1, sp. eg-4 by Eguchi et al. (2011).

Type Material
Holotype worker. Y Linh Ho, Sa Pa, Lao Cai, VIETNAM, Small fragment of forest (c. 1100 m alt.), 1.v.2002 (Eg02-VN-225) (K. Eguchi). Paratypes. Two workers, same data as holotype (ACEG, KUEC); three workers, Y Linh Ho, Sa Pa, Lao Cai, VIETNAM, Small fragment of forest (c. 1100 m alt.), 1.v.2002 (Eg02-VN-215) (K. Eguchi).

Etymology
The species name is dedicated to Dr. Bui T. Viet, who helped with field surveys in Vietnam.

References based on Global Ant Biodiversity Informatics

 * Hosoichi S., and K. Ogata. 2016. Systematics and biogeography of the ant genus Crematogaster Lund subgenus Orthocrema Santschi in Asia (Hymenoptera: Formicidae). Zoological Journal of the Linnean Society 176: 547–606.