Recurvidris chanapaithooni

The type series was collected using honey baits from the forest floor in a lowland evergreen forest. Recurvidris chanapaithooni inhabits primary forests and is sympatric with Recurvidris recurvispinosa in the eastern part and with Recurvidris browni in the southern part of Thailand. (Jaitrong and Wiwatwitaya 2015)

Identification
Jaitrong and Wiwatwitaya (2015) - Recurvidris chanapaithooni is closely related to Recurvidris kemneri, Recurvidris nigrans, and Recurvidris proles (all belonging to the R. kemneri group) in having 4 teeth on the masticatory margin of the mandible, sharp basal tooth, a small tooth on the basal margin. This species is most similar to R. kemneri, both sharing a small body size and clear yellow body colour. However, R. chanapaithooni is distinguished from R. kemneri by the presence of 2 pairs of hairs on propodeal dorsum (hairs absent in R. kemneri). It can be separated from R. proles by the following characteristics: body colour uniformly yellow in R. chanapaithooni (head brown, much darker than yellowish mesosoma in R. proles); petiole with a long acute anteroventral process in R. chanapaithooni (subpetiolar process- a small triangular tooth in R. proles); body much smaller (HW 0.38-0.41 mm in R. chanapaithooni; 0.66-0.68 mm in R. proles). R. chanapaithooni is easily separated from R. nigrans by the following characteristics: a much smaller body size (HW 0.38-0.41 mm in R. chanapaithooni; HW 0.61-0.65 mm in R. nigrans); clear yellow body colour in R. chanapaithooni (body colour dark in R. nigrans); tooth on basal margin of mandible smaller than fourth tooth in R. chanapaithooni (almost as large as fourth tooth in R. nigrans); promesonotum with 11-13 hairs in R. chanapaithooni (with nine hairs in R. nigrans); dorsum of propodeum superficially reticulate in R. chanapaithooni (smooth and shiny in R. nigrans); petiole finely reticulate in R. chanapaithooni (smooth and shiny in R. nigrans).

Distribution
Thailand (Chanthaburi, Chachoengsao and Trang Provinces).

Distribution based on Regional Taxon Lists
Oriental Region: Thailand.

Nomenclature

 * . Recurvidris chanapaithooni Jaitrong & Wiwatwitaya, 2015: 106, fig. 2 (w.) THAILAND.
 * Type-material: holotype worker, 3 paratype workers.
 * Type-locality: holotype Thailand, Chanthaburi Prov., Soi Dao Dist., 17.i.2008, WJT170108-1, honey bait trap (W. Jaitrong); paratypes with same data.
 * Type-depository: TNHM.
 * Status as species: Jaitrong, Tokeeree, et al. 2019: 60 (in key).
 * Distribution: Thailand.

Worker
Holotype and paratypes (n = 4): TL 2.00-2.10 mm, HW 0.38-0.41 mm, HL 0.36-0.40 mm, SL 0.35-0.36 mm, PW 0.21-0.25 mm, ML 0.53-0.54 mm, CI 104-105, SI 88-96. Non-type (n = 7): TL 1.95-2.10 mm, HW 0.36-0.41 mm, HL 0.36-0.40 mm, SL 0.35-0.36 mm, PW 0.21-0.25 mm, ML 0.53-0.54 mm, CI 100-105, SI 88-96.

(Holotype and paratypes). Head in full-face view round and almost as long as broad, with posterior margin convex. Eye 0.11-0.13 mm in maximum diameter, with eight ommatidia along longest axis. Antennal scape extending posteriorly slightly beyond posterolateral corner of head. Masticatory margin of mandible with four sharp teeth, fourth (basal) tooth larger than third; basal margin with a small tooth. Clypeus without paired carinae, its anterior margin convex. Promesonotum in profile strongly convex dorsally and sloping gradually to metanotal groove. Propodeum in profile with strongly convex dorsal outline; propodeal spines slender, divergent, and in caudal view very narrow. Propodeal declivity lacking infradental lamella or ridge linking propodeal spine to metapleural lobe. Peduncle of petiole relatively long, with its dorsal outline concave and ending posteriorly in right angle, its ventral outline convex with long acute subpetiolar process.

Head entirely smooth and shiny, lacking sculpture except some short longitudinal rugulae near mandiblular base. Mandible and antennal scape smooth and shiny. Promesonotum and lateral face of propodeum smooth and shiny; mesopleuron reticulate, partly smooth and shiny; propodeal dorsum and propodeal spine superficially reticulate. Petiole entirely reticulate; dorsum of postpetiole smooth and shiny. Gaster smooth and shiny.

Head with relatively dense short hairs; promesonotum with sparse longer hairs (11-13 hairs); longest pronotal hairs 0.10-0.13 mm long; propodeum dorsally with two pairs of short standing hairs in front of spiracles. Petiole with two dorsal pairs of long hairs. Postpetiole with two dorsal pairs of long hairs and one ventrolateral pair of short hairs. Body colour yellow.

Type Material
Holotype (THNHM-I2015-00295) and three paratype workers (THNHM-I2015-00296, THNHM-I2015-00297, and THNHM-I2015-00298) from E. Thailand, Chanthaburi Prov., Soi Dao Dist., honey bait trap, 17.i.2008, W. Jaitrong leg., WJT170108-1.

Etymology
The specific name is dedicated to Mr. Sakorn Chanapaithoon, Vice President and Acting President of National Science Museum, Thailand who has supported W. Jaitrong in his myrmecological research in Thailand and Laos.

References based on Global Ant Biodiversity Informatics

 * Jaitrong W., and D. Wiwatwitaya. 2015. The species of the ant genus Recurvidris Bolton, 1992 (Hymenoptera: Formicidae: Myrmicinae) in Thailand. Halteres 6: 104-112.