Two new species and a new record of the ant genus Meranoplus Smith, 1853 (Hymenoptera, Formicidae, Myrmicinae) from Thailand Author Yodprasit, Kuntima https://orcid.org/0009-0000-5012-0498 Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok, 10900, Thailand Author Buddhakala, Nopparat 0000-0002-8353-3851 Division of Biology, Faculty of Science and Technology, Rajamangala University of Technology Thanyaburi, Pathum Thani, 12120 Thailand Author Tasen, Wattanachai https://orcid.org/0009-0004-1794-6940 Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok, 10900, Thailand Author Jaitrong, Weeyawat 0000-0003-1362-0754 Division of Biology, Faculty of Science and Technology, Rajamangala University of Technology Thanyaburi, Pathum Thani, 12120 Thailand & Office of Natural Science Research, National Science Museum, 39 Moo 3, Khlong 5, Khlong Luang, Pathum Thani, 12120, Thailand text ZooKeys 2024 2024-08-26 1210 207 227 journal article 10.3897/zookeys.1210.125990 B158276E-7AC6-40AF-8713-0881D42F3953 Meranoplus tanomtongi Yodprasit & Jaitrong sp. nov. Figs 3 A – D , 5 A, B, E – G Types. Holotype : • worker ( THNHM -I-00028903 , THNHM ), northeastern Thailand , Kalasin Province , Kuchinarai District , Nong Hang Subdistrict , dry dipterocarp forest , 16.5559 ° N , 104.1089 ° E , 10 December 2007 , W. Jaitrong leg., TH 07 - WJT- 1010, honey baiting trap . Paratypes : • 10 workers ( THNHM -I-00028904 to THNHM -I-00028913 ), same data as holotype . The paratypes are deposited in THNHM . Non-type material examined. Laos . Central : • 4 workers ( THNHM -I-00028914 , THNHM ), Vientiance Province , Pak Ngum District , Ban Pha Dang , dry evergreen forest , 18.2716 ° N , 102.9639 ° E , 12 June 2010 , W. Jaitrong leg., WJT 10 - LAO 111 • 1 worker ( THNHM -I-00028915 , THNHM ), same locality and date, Sk. Yamane leg., LA 10 - SKY- 096, sandy soil . Thailand . Northeastern : • 1 worker ( THNHM -I-00028916 , THNHM ), Mukdahan Province , Kham Cha-e District , Kheang Chang Niam Village , mixed deciduous forest , 16.5698 ° N , 104.2703 ° E , 8 June 2007 , unknown collector • 1 worker ( THNHM -I-00028917 , THNHM ), same locality, 4 August 2007 , P. Kosonpanyapiwat leg. • 4 workers ( THNHM -I-00028918 , THNHM ), same locality and collector, 2 September 2007 . Figure 3. Meranoplus tanomtongi sp. nov. (holotype, THNHM - I- 00028903 ) A head in full-face view B body in profile view C promesonotal shield in dorsal view D body in dorsal view. Measurements and indices. Holotype worker: HL 0.63, HW 0.65, ML 0.65, PML 0.51, PW 0.65, SL 0.45, TL 2.72, CI 103, PMI 129, SI 70. Paratype workers ( n = 5): HL 0.62–0.65, HW 0.61–0.65, ML 0.62–0.68, PML 0.48–0.52, PW 0.61–0.70, SL 0.45–0.46, TL 2.62 – 2.85, CI 98–104, PMI 122–140, SI 68–74. Description of worker. Head in full-face view subquadrate, almost as long as broad, with sides weakly convex, posterior margin weakly convex, posterolateral corners bluntly angulate. Antennal scapes short, only reaching level of posterior margin of compound eyes, apical half incrassate; antennal segment II slender, longer than each of segments III – VI, and almost as long as III + IV + V; segment VI broader than each of segments II – V. Clypeus roughly subrectangular, shorter than broad, its anterior margin feebly concave, while posterior clypeal margin almost straight. Mandibles subtriangular, masticatory margin with four teeth. Compound eyes large, strongly convex in full-face view, located laterally behind mid-length of head, with eight ommatidia along longest axis, each facet round or elliptical (Fig. 5 G ). Frontal lobes broad, its anterior corners round, its lateral margin weakly convex (Fig. 5 E ). Frontal carinae long, reaching posterolateral corners of head. Mesosoma in dorsal view promesonotal shield distinctly shorter than broad, laterally convex, sinuate, margined and slightly overhanging mesosoma; lateral and posterior portions of promesonotal shield with translucent fins; posterior margin of promesonotal shield sinuate and distinctly concave; anterior corners of pronotum and posterior corners of mesonotum bluntly angulate; promesonotal shield with two pairs of fenestrae laterally; metanotal groove absent. Declivity of propodeum almost invisible from above, overhung by posterior margin of promesonotal shield (propodeal spines are visible in profile). Mesosoma in profile subquadrate, weakly convex dorsal outline, lateral face of mesosoma flat; lateral face of pronotum subtriangular; metapleuron not clearly demarcated from mesopleuron and lateral face of propodeum. Propodeal spines long and acute, located at middle of propodeal length, in profile. Petiole in profile subtriangular, both anterior and posterior faces weakly convex; when viewed from behind, dorsal margin transverse and smoothly convex. Subpetiolar process low, its ventral outline weakly convex, with small anterior denticle. Postpetiole in profile subquadrate, shorter than high; in dorsal view, distinctly shorter than broad, anterior margin almost straight, while posterior margin distinctly convex; dorsum of postpetiole shallowly concave marginated with sinuate ridge, posterior face convex. Gaster larger than head and mesosoma combined; first gastral tergite largest, in dorsal view, its anterior margin distinctly concave. Sculpture. Mandibles striate but shiny. Antennal scapes superficially striate. Dorsum of head in full-face view entirely reticulate; posterior half of antennal scrobes shagreened mixed with a few transverse ridges. Dorsum of promesonotal shield distinctly reticulate but median region with weaker reticulation than elsewhere; in profile, upper half portion of lateral faces of pronotum shagreened, while lower half portion with sparse irregular ridges; upper one-third portion of mesopleuron shagreened, lower two-third portion weakly longitudinally striate; metapleuron and lateral face of propodeum smooth and shiny. Propodeum declivity superficially shagreened. Petiole smooth and shiny. Postpetiole somewhat smooth but upper portion of posterior face with wrinkles. First gastral tergite superficially shagreened with smooth and shiny interspaces. Pilosity and coloration. Dorsum of head with dense erect hairs (usually a closed cell with a hair), hairs along head margin clearly longer than hairs on middle of head; antennae with dense, suberect hairs; promesonotal shield with dense, erect hairs; legs with dense suberect hairs; in profile, lower two-thirds of pronotum with sparse suberect hairs; lower one-third of mesopleuron and metapleuron with sparse suberect hairs; area around propodeal spiracle with sparse, suberect hairs; femora and tibiae with numerous long, outstanding hairs as well; petiole with sparse, erect hairs on its dorsum; postpetiole with dense, long, erect hairs, except anterior face without hairs; femora and tibiae with numerous long, outstanding hairs as well; gaster with dense, long, erect hairs. Dorsum of body (head, mesosoma, and gaster) and waist yellowish brown; mandibles, antennae, legs, and tip of gaster yellow. Distribution. Laos ( Vientiane Province ), Thailand ( Kalasin and Mukdahan Provinces, Fig. 4 ). Figure 4. Distribution of Meranoplus Thai species in Thailand. Etymology. The specific name is dedicated to Professor Alongklod Tanomtong of Khon Kaen University, who is an excellent specialist in biological sciences in Thailand , who helped and inspired many young biologists. Habitat. This species can be found in lowland primary forest ( 300–600 m a. s. l.). The type series was collected from a dry dipterocarp forest. Lao specimens (colony code WJT 10 - LAO 111) were collected from a dry evergreen forest. Specimens from Mukdahan Province , northeastern Thailand were collected in a mixed deciduous forest. Figure 5. Characters used in key A, B, E Meranoplus tanomtongi (holotype, THNHM - I 00028903) F, G M. tanomtongi (non-type worker, THNHM - I- 00028904 ) C, D M. bicolor (non-type, THNHM - I- 00027270 ) H M. siamensis (holotype, THNHM - I- 00027303 ) I M. siamensis (non-type worker, THNHM - I- 00028942 ) A, C petiole and postpetiole in profile B, D petiole and postpetiole in dorsal view E, H anterior corners of frontal lobes F, I head in full-face view G eye. Differential diagnosis. Meranoplus tanomtongi sp. nov. is a small species that is most similar to M. siamensis sp. nov. , see differential diagnosis under M. siamensis . This species is also similar in general appearance to M. malaysianus and M. borneensis from Sundaland, in having two pairs of fenestrae along each lateral margin of the promesonotal shield and having a concave anterior margin of first gastral tergite. However, M. tanomtongi can be distinguished from M. malaysianus and M. borneensis by 1) anterior corners of frontal lobes round and lateral margin weakly convex (right angled and lateral margin almost straight in M. malaysianus and M. borneensis ); 2) petiole in profile subquadrate, almost flat dorsally (round, usually convex dorsal outline in M. malaysianus and M. borneensis ); 3) entire lateral margin of the promesonotal shield is serrate and convex (parallel sides in M. malaysianus and M. borneensis ); 4) in profile, the tip of petiole acute (truncate in M. malaysianus and M. borneensis ); 5) head in full-face view entirely reticulate (densely reticulate-rugulose in M. malaysianus and M. borneensis ); 6) the petiole and postpetiole are smooth and shiny (sculptured in M. malaysianus and M. borneensis ). Figure 6. Characters used in key A Meranoplus siamensis (non-type worker, THNHM - I 00028942) B, F M. castaneus (non-type, THNHM - I- 00027323 ) C M. laeviventris (non-type, THNHM - I- 00027329 ) D, E M. bellii (lectotype, CASENT 0908933 ) G, H M. dlusskyi (in Zryanin 2015 ) I M. levis (holotype, CASENT 0902025 ) A eye B, C petiole and postpetiole in profile D, F, G, I mesosoma in profile E gaster in dorsal view H head in profile.