Echinopla jeenthongi

This rare species, known only from southern Thailand, has been collected from lower vegetation in evergreen forests.

Identification
Tanansathaporn et al. (2018) – A member of the Echinopla mezgeri group. Medium-sized, HW 0.96–1.04 mm, head in full-face view elliptical, clearly longer than broad; eye relatively large, weakly convex; mesosoma very elongated and subcylindrical; pronotum with tooth-like angles; in dorsal view mesosoma with waist-like incision in front of propodeum; promesonotal suture almost absent; metanotal groove distinct with shallow depression; petiole in profile subtriangular, in dorsal view transverse and armed with two spines; first gastral tergite in dorsal view elliptical, much longer than broad, its posterior margin with numerous small denticles. Dorsa and lateral face of head, mesosoma, petiole and first gastral tergite with dense macropunctures. Dorsum and lateral face of head, mesosoma petiole, and first gastral tergite without long standing hairs; clypeus, mandible and first gastral sternite with sparse long hairs. Entire body black; antenna dark brown, leg reddish brown.

Closely related to Echinopla mezgeri. Both species lack long standing hairs on the body surface. However, E. jeenthongi can be distinguished from E. mezgeri by the following characteristics: entire head, mesosoma, petiole and first gastral tergite finely macropunctate (finely punctate, except mesopleuron and lateral face of propodeum covered by a coarse punctuation in E. mezgeri); posterior margin of first gastral tergite with numerous small denticles (without serration in E. mezgeri); basal half of femora yellowish brown (dark brown in E. mezgeri); sparse short pubescent hairs on dorsum of mesosoma (very dense in E. mezgeri). Echinopla tunkuabduljalilii, a third species of the Echinopla mezgeri group from West Malaysia, differs from both species by a strongly reduced puncturation of mesosoma and gaster tergite 1, and from E. jeenthongi also by a non-serrate hind margin of gaster tergite 1.

Distribution
Surat Thani, Nakhon Si Thammarat and Phangnga provinces, Thailand.

Distribution based on Regional Taxon Lists
Oriental Region: Thailand.

Nomenclature

 *  jeenthongi. Echinopla jeenthongi Tanansathaporn & Jaitrong, 2018: 6, figs. 4-9 (w.q.) THAILAND.

Worker
Holotype: TL 3.80, HL 1.12, HW 1.04, SL 1.12, ED 0.24, PW 0.92, MSL 1.62, PL 0.53, PH 0.50, DPW 0.96, GW 1.25, CI 93, EI 23, SI 108, LPI 94, DPI 181. Paratypes (n = 2): TL 4.40–4.50, HL 0.89–1.15, HW 0.96–1.00, SL 1.06–1.15, ED 0.23–0.25, PW 0.85–0.86, MSL 1.72–2.35, PL 0.65–0.66, PH 0.53–0.60, DPW 0.73               , EI 24–25, SI 110–115, LPI 80–92, DPI 111–123.

Head in full-face view clearly longer than broad, elliptical, with weakly convex lateral margin and convex posterior margin. Eye relatively large, moderately protruding, located at mid-length of head. Frontal lobe horizontal, in full-face view covering antennal fossa only in part. Mandible short, subrectangular, anterior margin slightly convex, and its masticatory margin armed with five teeth. Clypeus broad, anterior margin almost straight, while posterior margin strongly convex. Frontal carina short, not surpassing level of anterior margin of eye. Antennal scape moderately long, steadily widened from base to apex, slightly extending beyond posterior margin of head; antennal segment II clearly narrower and longer than each of III–VI; terminal segment (XII) almost as long as X and XI combined.

Mesosoma very elongated and subcylindrical, promesonotum clearly larger than propodeum in dorsal view. In profile dorsal outline of mesosoma weakly convex; promesonotal suture absent, but laterally indicated by short row of puncture; metanotal groove weakly impressed; propodeal outline strongly convex dorsally; propodeal declivity weakly convex. In dorsal view mesosoma with waist-like incision in front of propodeum; promesonotum clearly longer than broad; pronotum with pair of tooth-like protrusions; maximum pronotal width slightly narrower than head excluding eyes. In dorsal view, propodeum suboval, narrowed anteriorly, clearly longer than broad, with lateral and posterior margins convexs; proprodeal spiracle protruding laterally. Legs relatively long and slender.

Petiole in profile subtriangular, as long as high, ventral outline feebly concave. In dorsal view petiole transverse, about as broad as propodeal width, its anterior face as broad as posterior face. In posterior aspect dorsal margin with two spines; lateral margin without denticles or teeth.

First gastral tergite in dorsal view elliptical, much longer than broad, broader posteriorly, covering remaining tergites, posterior margin convex with numerous small denticles.

Dorsum and lateral face of head finely macropunctate, except frontal lobe punctate; mandible with dense puncture at base, smooth and shiny along masticatory margin and apex; antennal scape finely punctate. Mesosoma entirely macropunctate, except anterior-most portion punctate. Petiole and first gastral tergite macropunctate. Legs reticulate with smooth and shiny interspaces. Dorsum of head, mesosoma, petiole, and first gastral tergite without erect hairs; clypeus, mandible, and apex of scape with sparse erect hairs; gastral sternites with dense hairs.

Entire body black; mandible reddish brown; antenna dark brown, with tip of scape reddish brown and antennal segment XII yellowish brown; coxae, trochanter, and basal half of femora yellowish brown; apical half of femora, tibiae, and tarsi reddish brown.

Queen
Dealate. Body size slightly larger than worker. Head in full-face view longer than broad, elliptical, with weakly convex side. Compound eye relatively large, moderately protruding, positioned at mid-length of head. Ocelli present, distance between lateral ocelli longer than distance between anterior and lateral ocellus. Mandible short, subrectangular, outer margin slightly convex, its masticatory margin armed with five teeth. Clypeus broad, its anterior margin almost straight, while posterior margin strongly convex. Antennal scape moderately long, steadily widened from base to apex, slightly extending beyond posterior margin of head. Mesosoma elongated. In dorsal view, pronotum short, separated from mesoscutum by a suture, its anterolateral corner armed with a short, truncate tooth; mesoscutum

large, slightly longer than broad, its anterior margin strongly convex, while posterior margin almost straight; mesoscutellum trapezoidal, slightly broader than long, anterior margin weakly convex, separated from mesoscutum and metanotum by shallow sutures; metanotum very short, separated propodeum by a deep suture; propodeum larger than mesoscutellum, anterior margin feebly concave and posterior margin convex; in profile mesopluron broad, anepisternum separated from katepisternum by a transverse mesoplural groove; metapleuron not demarcated from lateral face of propodeum.

Petiole in profile view subtriangular, as long as high. In dorsal view petiole transverse, slightly narrower than propodeum. In posterior aspect dorsal margin with 2 spines laterally.

First gastral tergite in dorsal view elliptical, much longer than broad, broader posteriorly, covering remaining gastral tergites, posterior margin convex with numerous small denticles.

Sculpture, setae and colour condition similar to those of worker caste. Posterior portion of first gastral tergite with four short erect hairs.

Type Material
Holotype – worker (THNHM-I-01368), S Thailand: Na- khon Si Thammarat province, Sichon district, Khao Noi subdistrict, near Yod Nam Waterfall, 8.9091°N, 99.7319°E, 1.XI 2008, leg. T. Jeenthong. Paratypes: one worker (NW310705-1), S Thailand, Surat Thani province, Ban Nasarn district, Julaporn, 8.8613°N, 99.4847°E, evergreen forest, 400–550 m, lower vegetation, 31.VII 2005, leg. N. Noon-anant ; one worker (NW150405-2), S Thailand, Nakhon Si Thammarat province, Noppitam district, Noppitum [Noppitam] sub- district, Krung Ching, 8.6572°N, 99.6363°E, 100–300 m, lower vegetation, 15.IV 2005, leg. N. Noon-anant (PSU); one dealate gyne (NW091105-3), S Thailand, Phangnga province, Muang Phangnga, Song Prang sub-district, 8.6111°N, 98.5505°E, 200–300 m, lower vegetation, 09.XI 2005, leg. N. Noon-anant (PSU).

Etymology
We dedicate this species to Mr. Tadsanai Jeenthong (National Science Museum, Thailand), who donated the holotype to THNHM.

References based on Global Ant Biodiversity Informatics

 * Tanansathaporn S., H. Zettel, N. Pinkaew, M. Kongmee, S. Waengsothorn, and W. Jaitrong. 2018. Two new species of the genus Echinopla Smith, 1857 (Hymenoptera: Formicidae: Formicinae) from Thailand. Far Eastern Entomologist 370: 1-11.