A revision of the Carebara pygmaea (Emery, 1887) species group (Hymenoptera: Formicidae) in Thailand Author Wimolsuthikul, Chaipat 0009-0001-7229-4752 Office of Natural Science Research, National Science Museum, 39, Moo zygosoma@gmail.com Author Yamane, Seiki 0000-0002-6865-0865 Haruyama-chô 1054 - 1, Kagoshima-shi, 899 - 2704 Japan. mayiopa0@gmail.com Author Samung, Yudthana 0000-0003-4069-4257 Khlong & Department of Medical Entomology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand. yudthana.sam@mahidol.ac.th Author Jaitrong, Weeyawat 0000-0003-1362-0754 Office of Natural Science Research, National Science Museum, 39, Moo & Office of Natural Science Research, National Science Museum, 39, Moo & Khlong Luang, Pathum Thani, 12120 Thailand. polyrhachis@yahoo.com text Zootaxa 2024 2024-07-15 5481 1 79 100 http://dx.doi.org/10.11646/zootaxa.5481.1.5 journal article 299942 10.11646/zootaxa.5481.1.5 0423a610-a41f-4de4-9d39-289e7ec7168f 1175-5326 12742641 987E3EFF-7867-4186-A26A-79359DF762C8 Carebara adisaki Wimolsuthikul & Jaitrong , sp. nov. ( Figs. 1–2 ) Type materials : Holotype major worker ( THNHM-I-27491 , THNHM ), western Thailand , Tak Province , Umphang District , Thung Yai Naresuan East W.S. , Thung Nanoi Station , Peat Swamp Forest , 15.737505ºN , 98.997927ºE , 992 m a.s.l. , 18.II.2015 , W. Jaitrong leg., TH15-WJT-355 . Paratypes : 1 major worker ( THNHM-I-27492 , THNHM ) and 8 minor workers ( THNHM-I-27493 to THNHM-I-27498 , THNHM ; THNHM-I-27499 to THNHM-I-27450 , SKYC ) , same data as holotype . Measurements (in mm). Holotype (major worker): TL 4.06, HL 1.12, HW 1.06, SL 0.53, ED 0.1, ML 0.92, MW 0.5, DPW 0.26, PL 0.59, PH 0.3, CI 94.12, SI 50, PI1 200, PI2 44.44. Major worker ( paratype ): TL 3.86, HL 1.09, HW 1.02, SL 053, ED 0.07, ML 0.89, MW 0.46, DPW 0.23, PL 0.53, PH 0.3, CI 94, SI 52, PI1 178, PI2 45. Minor worker (n= 5 paratypes ): TL 1.98–2.18, HL 0.5–0.53, HW 0.43–0.46, SL 0.43–0.5, ED 0.01–0.02, ML 0.53–0.59, MW 0.26–0.3, DPW 0.13–0.17, PL 0.33–0.4, PH 0.13–0.17, CI 87–88, SI 100–108, PI1 240–275, PI2 40–45. Diagnosis. Major: head and gastral tergite I with sparse erect hairs; promesonotum without erect hairs; with head in full-face view, posterior one-third with transverse striation, while anterior two-thirds with longitudinal striation; eye small, with ca. 10 ommatidia; gastral tergite I superficially shagreened with smooth and shiny interspaces; propodeal spine shorter than diameter of propodeal spiracle. Minor: propodeal dorsum smooth and shiny; petiole and postpetiole with decumbent hairs; propodeal junction bluntly angulate; body reddish brown. FIGURE 1. Carebara adisaki Wimolsuthikul & Jaitrong , sp. nov. , holotype major worker (THNHM-I-27491). A, Body in profile view; B, head in full-face view; C, body in dorsal view. Descriptions. Major worker ( Fig. 1 ). Head in full-face view, subrectangular, slightly longer than broad, broadened at posterior one-third of head length; cephalic median furrow well developed, extending posteriad to posterior margin of head. Mandible short, subtriangular. Clypeus broad, anterior margin sinuate, feebly concave medially. Frontal lobe poorly developed, only partly covering antennal socket; frontal carina inconspicuous, reaching level of anterior margin of eye. Eye small, with ca. 10 ommatidia, located at anterior ¼ of head length laterally. Antenna 11-segmented with 2-segmented club; scape thin, clavate (its width at apex smaller than combined length of segments X–XI), and short (when laid backward reaching midlength of head). Mesosoma in profile smaller than each of head and gaster; with mesosoma in dorsal view, pronotum convex; promesonotal suture indistinct, present as weak groove; metanotal groove distinct. Mesonotum in profile view short, raised around midlength, clearly demarcated from metapleuron by deep groove. In profile view propodeal dorsal outline almost straight and slightly slope down posteriorly. Propodeal spine in dorsal view short and subtriangular, pointed posterolaterally. Petiole with long anterior peduncle, its node in profile relatively short, clearly shorter than high; in dorsal view slightly broader thang long, in profile view with weakly convex dorsal outline. Postpetiole in profile round almost as long as high; in dorsal view postpetiole almost as long as broad and broader than petiole. Gaster almost as large as head; anterior margin in dorsal view almost straight. FIGURE 2. Carebara adisaki Wimolsuthikul & Jaitrong , sp. nov. , paratype minor worker (THNHM-I-27500). A, Body in profile view; B, head in full-face view; C, body in dorsal view. With head in full-face view, posterior one-third with transverse striation, while anterior two-thirds with longitudinal striation (slightly curved posteriorly), lateral and ventral faces somewhat shiny. Mandible smooth and shining. Clypeus smooth and shiny in median area. Antenna somewhat smooth and shiny. Pronotum dorsally punctate but slightly shiny; lateral face smooth and shiny; mesopleuron finely punctate; propodeum somewhat smooth and shiny dorsally and punctate laterally; legs entirely smooth and shiny. Petiole laterally punctate; its node smooth and shiny. Postpetiole entirely finely punctate. Gastral tergite I superficially shagreened with smooth and shiny interspaces. Dorsum of head entirely covered with dense short decumbent hairs, lacking erect hairs on posterior half; mandible covered with sparse decumbent hairs; clypeus smooth and shiny in median area; antenna with dense appressed hairs. Body reddish brown; antenna and legs yellowish brown. Minor worker ( Fig. 2 ). Head in full-face view longer than broad; lateral margin convex and posterior margin almost straight. Mandible short, subtriangular. Clypeus broad, its anterior margin roundly convex. Frontal lobe poorly developed, only partly covering antennal socket; frontal carina inconspicuous, reaching level of eye. Eye small, with one ommatidium, located at anterior ¼ of head length laterally. Antenna 11-segmented, with 2-segmented club; scape thin and clavate (its width at apex almost as large as length of segment X), when laid backward extending beyond mid-length of head but not reaching posterolateral corner of head. Mesosoma narrower than head and gaster; in profile view, mesonotum higher than propodeum, roundly convex, sloping gradually to metanotal groove; promesonotal suture indistinct; metanotal groove distinct; propodeum with weakly convex dorsal outline and blunt angle posterior junction. Mesopleuron in profile clearly demarcated from metapleuron by deep groove. Propodeum relatively short compared with pronotum, propodeal spine absent. Petiole with long anterior peduncle; petiolar node in profile almost as long as high. Postpetiole in profile view clearly longer than high, weakly convex in dorsal outline; in dorsal view postpetiole slightly longer than broad and broader than petiole. Gaster as large as head, in dorsal view anterior margin concave. Head, promesonotum, dorsum of propodeum, nodes of petiole and postpetiole, and gaster entirely smooth and shiny; clypeus and mandibles smooth and shiny; antennal scapes somewhat smooth and shiny; mesopleuron finely punctate; metapleuron largely smooth; lateral face (around propodeal spiracle) and propodeal declivity punctate; legs smooth and shiny; peduncle of petiole punctate; gastral tergite I smooth and shiny. Head entirely covered with dense short decumbent hairs, and 2–3 pairs of erect hairs on frontal carinae; antenna with dense decumbent hairs; dorsum of mesosoma entirely without erect hairs; pronotum with dense short decumbent hairs; propodeal dorsum with a few decumbent hairs; legs with numerous short decumbent hairs; petiole with sparse short decumbent hairs; postpetiole covered with sparse erect hairs; gastral tergite I covered with dense short decumbent hairs; few erect hairs present along its posterior margin. Body reddish brown; mesosoma darker than head and gaster; antenna and legs yellowish-brown. Etymology. The specific name is dedicated to Mr. Adisak Phusitwongsanuyut (Department of National Parks, Wildlife and Plant Conservation), who supported W. Jaitrong for his field survey in Thailand . Habitat. The type series was collected from a large rotting log near the forest edge. Distribution. Thailand ( Tak Province , Fig. 13 ). Remarks. Carebara adisaki is most closely related to C. parva and C. bokorensis . It can be separated from C. bokorensis by the following characteristics in the major worker: 1) posterior one-third of head dorsum with transverse striation (without striation in C. bokorensis ); 2) gastral tergite I superficially shagreened and shiny (punctate in C. bokorensis , see Fig. 1A and Fig. 3A for comparison); 3) posterior half of head dorsum and promesonotal dorsum without erect and decumbent hairs (dense hairs present in C. bokorensis , see 1A and Figs. 3A for comparison). This species can be separated from C. parva in the major worker by 1) propodeal spine shorter than diameter of propodeal spiracle (as long as or slightly longer than diameter of propodeal spiracle in C. parva ); 2) first gastral tergite with erect hairs along its posterior margin only (erect hairs covering entire segment in C. parva ). Minor worker of C. adisaki is similar to C. parva in having a smooth and shining propodeal dorsum, without erect hairs on petiole and postpetiole, and the blunt angle propodeal junction. However, C. adisaki is separated from C. parva by 1) larger species (HW 0.43–0.46 mm in C. adisaki ; HW 0.36–0.40 mm in C. parva ); 2) body colour darker (reddish brown in C. adisaki ; yellowish brown in C. parva ).