Lepisiota siamensis Jarernkong et Jaitrong, 2023

Jarernkong, K., Kongmee, M., Pinkaew, N. & Jaitrong, W., 2023, Three new species of the ant genus Lepisiota Santschi, 1926 (Hymenoptera: Formicidae) from Thailand, Far Eastern Entomologist 468, pp. 1-15 : 6-9

Lepisiota siamensis Jarernkong et Jaitrong , sp. n.

https://zoobank.org/NomenclaturalActs/ 73BC33F2-E611-49C2-94FD-AB2DADFDCB66

Fig. 2

TYPE MATERIAL. Holotype – worker (THNHM-I-26819, THNHM), N Thailand: Chiang Rai Province, Muaeng District, Pong Nam Ron Village , 21.X 2018, W. Jaitrong leg., WJT211018-06. Paratypes: 23 workers (THNHM-I-26820 to THNHM-I-26841, THNHM), same data as holotype.

DESCRIPTION. Worker ( Fig. 2 ).

Measurements and indices. Holotype: HL 0.56, HW 0.52, EL 019, SL 0.56, ML 0.79, FeL 0.66, PL 0.29, PH 0.23, CI 94, SI 106, EI 37, FeI 80.

Paratypes (n = 23): HL 0.52–0.59, HW 0.46–0.52, EL 0.16–0.19, SL 0.56–0.62, ML 0.72–0.82, FeL 0.62–0.69, PL 0.26–0.29, PH 0.19–0.23, CI 87–94, SI 106–135, EI 31–40, FeI 71–80.

Head: in full-face view, slightly longer than broad, lateral margins convex, posterior margin almost straight medially. Mandibles subtriangular; masticatory margin with five teeth, including largest apical tooth, followed by medium-sized preapical tooth, a small tooth, medium-sized prebasal tooth, and small basal tooth; basal margin without denticles. Clypeus broad and convex medially, shorter than broad, its anterior margin convex, posterior margin convex medially. Eyes relatively large, oval, convex, with 17–19 ommatidia along the longest axis, located at midlength of head laterally; outer margin of eye reaching lateral margin of head. Ocelli present, located on frons; lateral ocelli slightly larger than median ocellus; distance between lateral ocelli slightly longer than distance between median ocellus and lateral ocellus. Antennal scapes slender, clavate. Antennal segment II longer than broad and longer than segments III and IV; segments V–X each thin and longer than broad. Frontal lobe narrow and frontal carina short slightly extending beyond level of anterior margin of eye.

Mesosoma: in profile pronotum with its dorsal outline weakly convex; mesonotum almost straight and sloping gradually to metanotal groove; in dorsal view, pronotum almost as long as broad and clearly broader than mesonotum but slightly broader than propodeum; metathoracic spiracle in profile raised at least to the level of base of propodeal spine; promesonotal suture and metanotal groove distinct; mesopleuron clearly demarcated from metapleuron by deep groove; metapleuron not demarcated from lateral face of propodeum. Propodeum in profile with its dorsal outline weakly convex; in profile, propodeal spine short, subtriangular, blunt tip, slightly shorter than broad at base; in dorsal view, tip of propodeal spine pointed backward and outward.

Petiole sessile; in profile petiolar node subtriangular, longer than high, its anterior margin weakly convex, while posterior margin concave; dorsum of petiole with a pair of sharp spines; subpetiolar process weakly developed, its ventral outline weakly convex; in dorsal view petiolar node subrectangular, longer than broad, narrower posteriorly.

Dorsum of head densely reticulate with smooth and shiny interspaces; area in front of eye laterally (lower gena) finely striate; ventral surface of head smooth and shiny; pronotum entirely smooth and shiny; mesopleuron with dense longitudinal striation except for lower portion smooth; propodeum punctate; petiole and gaster largely smooth and shiny. Antennal scape punctate; coxae smooth and shiny; femora superficially reticulate with smooth and shiny interspaces; tibiae punctate.

Dorsum of head with sparse standing hairs mixed with short appressed hairs; pronotum with sparse standing hairs mixed with sparse short appressed hairs; mesonotum with less than 10 standing hairs; propodeal dorsum with 5–6 standing hairs mixed with very short appressed hairs; gaster with dense standing hairs, hairs on gastral sternites longer than on tergite. Body entirely black to dark brown. Mandible, antenna, and legs reddish brown to yellowish brown.

REMARKS. Lepisiota siamensis sp. n. is most similar to L. lunaris (Emery, 1893) from India in having a dark to black and shining body, a reticulated head, and yellowish-brown antennae. However, L. siamensis can be easily separated from L. lunaris by 1) head slightly longer than broad (almost as long as broad in L. lunaris); 2) area between eye and mandibular base finely striate (slightly smooth in L. lunaris); 3) outer margin of eye reaching lateral margin of head (not touching in L. lunaris); 4) pronotum as long as broad (shorter than broad in L. lunaris ); 5) in profile tip of propodeal spine bluntly angulated (tip of propodeal spine sharply angulated in L. lunaris ); 6) dorsal outline of propodeum weakly convex (almost straight in L. lunaris ); 7) petiolar spines pointed above (curve backward in L. lunaris). The new species is also similar to L. acuta Xu, 1994 in general appearance. However, it can be distinguished from the latter by 1) pronotum smooth and shiny (densely punctate in the latter); 2) in profile propodeal spines bluntly angulated (sharply angulated in the latter); 3) dorsal outline of propodeum weakly convex (straight in the latter); 4) petiolar spines pointed above (curve backward in the later); 5) femora reddish brown (darker in the latter).

HABITAT. The type series was collected from soil in a paddy field (the same locality as in the L. bicolor colony) at an elevation of about 900 m above sea level.

ETYMOLOGY. The specific name is an adjective meaning ‘of Siam’ the historic name of Thailand.

DISTRIBUTION. Thailand: Chiang Rai Province ( Fig. 6 ).

Figures

Fig 2. Lepisiota siamensis Jarernkong et Jaitrong, sp. n., holotype worker (THNHM-I- 26819, THNHM). A – body in profile view; B – head in full-face view; C – body in dorsal view.

Fig 6. Distributions of the new species of Lepisiota in Thailand.