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 pygmaea ( Emery, 1887 ) ( Figs. 10–12 ) Pheidologeton pygmaeus Emery, 1887: 465 . Type locality: Indonesia Combination in Pheidologeton ( Aneleus ) : Emery 1900: 327 ; in Aneleus : Emery 1924: 214 ; in Pheidologeton : Ettershank 1966: 119 ; in Carebara : Fischer et al . 2014: 72 . Senior synonym of Carebara albipes , Carebara bugnioni : Fischer et al. 2014: 72 . Pheidologeton pygmaeus var. albipes Emery, 1893: 266 (w.). Type locality: Philippines (CASENT0904655, images examined). Combination in Aneleus : Emery 1924: 214 ; in Pheidologeton : Ettershank 1966: 118 . Junior synonym of pygmeae : Fischer et al. 2014: 72 . Pheidologeton ( Aneleus ) pygmaeus var. bugnioni Forel, 1915: 28 (s.). Type locality: Sri Lanka (CASENT0908951, images examined). Combination in Aneleus : Emery 1924: 214 ; in Pheidologeton : Ettershank 1966: 118 . Junior synonym of Carebara pygmeae : Fischer et al. 2014: 72 . Pheidologeton ( Aneleus ) pygmaeus var. simalurensis Forel, 1915: 27 (s.w.q.). Type locality: Indonesia ( Sumatra ). Combination in Aneleus : Emery 1924: 214 ; in Oligomyrmex : Ettershank 1966: 124 ; in Carebara : Fernández 2004: 235 . Raised to species: Ettershank 1966: 124 . Junior synonym of Carebara pygmeae : Fischer et al. 2014: 72 . Type materials: Syntype major and minor workers, Indonesia , Ternate Island (images of syntype major worker, CASENT0904653 and syntype minor worker, ANTWEB CASENT0904654 available on AntWeb were examined) . Non-type material examined. Northern Thailand : Chiang Rai Province , Mae Fa Luang District , Mae Fa Luang Subdistrict , Doi Tung , 20.27194444ºN , 99.82194444ºE , 589 m a.s.l. , 22.X.2018 , W. Jaitrong leg., WJT221018- 43 ( THNHM ) . Western Thailand : Tak Province , Umphang District , Thung Yai Naresuan East W.S., Thung Na Noi Station , 15.736503ºN , 98.982209ºE , 960 m a.s.l. , 20.II.2015 , W. Jaitrong leg., TH15-WJT-411 ( THNHM ) ; Tak Province , Umphang District , Umphang W.S., Pha Luard Station , 15.978425ºN , 98.802883ºE , 451 m a.s.l. , 28.I.2015 , W. Jaitrong leg., TH15-WJT-125 ( THNHM ) ; Kanchanaburi Province , Thong Pha Phum District , Ban Lin Thin , 14.528377ºN , 98.747604ºE , 192 m a.s.l. , 29.XI.2003 , Sk. Yamane leg., TH03-SKY-145 ( SKYC , THNHM ) ; Petchaburi Province , Kang Krachan District , Huai Mae Priang Subdistrict , 12.809598ºN , 99.553971ºE , 266 m a.s.l. , 21. V .2023 , W. Jaitrong leg., TH23-WJT-849. Central Thailand : Nakhon Nayok Prov. Mueang Nakhon Nayok Dist., Ban Yai Subdist. , Wang Takrai Park , 14.333663ºN , 101.306068ºE , 55 m a.s.l. , 16 NOV 2023 W. Jaitrong leg. WJT151123–12( THNHM ) . Eastern Thailand : Chonburi Province , Bo Thong Dist. , Phuang Thong Subdistrict , Ban Ang Phaknam , dry evergreen forest, 13.178070ºN , 101.400494ºE , 105 m a.s.l. , 3.IV.2004 , W. Jaitrong leg., WJT04-E006 ( THNHM ) ; Rayong Province , Khao Cha Mao District , Huai Tabmon Subdistrict , Ban Sriraman , dry evergreen forest, 13.006519ºN , 101.714621ºE , 84 m a.s.l. , 5.IV.2004 , W. Jaitrong leg., WJT04-E028 ( THNHM ) ; Chachoengsao Prov. , Thatha Keab Dist. , 27.IV.2003 , W. Jaitrong leg., WJT03-TH-5 ( THNHM ) ; Chanthaburi Province , Lam Sing District , Ban Pheao , 12.519155ºN , 102.169837ºE , 27 m a.s.l. , 23.XI.2003 , W. Jaitrong leg., TH03-WJT-580 ( THNHM ) ; same locality, date and collector, TH03-WJT-563 ( THNHM ) ; Chanthaburi Province , Soi Dao District , Sai Khao Subdistrict , 13.064674ºN , 102.103291ºE , 139 m a.s.l. , 14.IV.2008 , W. Jaitrong leg., WJT08-E062 ( THNHM ) ; Chanthaburi Prov. , Pong Nam Ron Dist. , Khlong Tab Mak , 12.717072ºN , 101.264764ºE , 12 m a.s.l. , 18. V .2008 , W. Jaitrong leg., WJT08-E181 ( THNHM ) . Southern Thailand : Surat Thani Province , Tha Chang Dist. , Tha Chang Subdistrict , evergreen forest, 9.250764ºN , 99.146154ºE , 6 m a.s.l. , 27.II.2020 , W. Jaitrong leg., TH20-WJT-21 ( THNHM ) ; Surat Thani Province , Wipawadee District , Ta Kuk Nuar Subdistrict , 9.247103ºN , 98.870327ºE , 201 m a.s.l. , 27.II.2020 , Jaitrong leg., TH20-WJT-020 ( THNHM ) ; Surat Thani Province , Ban Na San District , Lam Phun Subdistrict , 8.881230ºN , 99.454145ºE , 127 m a.s.l. , 11.X.2011 , W. Jaitrong leg., TH11-WJT-26 ( THNHM ) ; Nakhon Si Thammarat Province , Sichon District , Khao Noi Subdistrict , Yod Nam , 8.919383ºN , 99.732740ºE , 239 m a.s.l. , 11.XII.2007 , W. Jaitrong leg., WJT07-TH1886 ( THNHM ) ; Trang Province , Nayong District , Khao Chong B.G., 7.556598ºN , 99.777994ºE , 64 m a.s.l. , 23.II.2020 , W. Jaitrong leg., TH20-WJT-02 ( THNHM ) ; Trang Prov. , Palian Dist. , Ban Kuan Mai Dam , Khao Ban Tad WS., Ton Tae Waterfall. , 7.293945ºN , 99.880681ºE , 67 m a.s.l. , 18 FEB 2022 W. Jaitrong leg. TH22–WJT–045 ( THNHM ) . Measurements (in mm). Major worker (n = 10): TL 4.13–4.16, HL 1.19–1.22, HW 1.02–1.06, SL 053– 0.56, ED 0.13–0.1, ML 0.89–0.96, MW 0.59–0.63, DPW 0.26, PL 0.33–0.35, PH 0.26–0.30, CI 86, SI 52–53, PI1 117–125, PI2 76–80. Minor worker (n = 10): TL 2.02–2.08, HL 0.46–0.50, HW 0.46–0.48, SL 0.36–0.40, ED 0.01–0.02, ML 0.50–0.53, MW 0.23–0.26, DPW 0.10, PL 0.20–0.23, PH 0.17, CI 93–100, SI 79–86, PI1 120–140, PI2 43–50. Dealete queen : TL 6.9, HL 1.25, HW 1.29, SL 0.79, ED 0.33, ML 2.21, MW 1.22, DPW 0.46, PL 1.12, PH 0.56, CI 103, SI 62, PI1 200, PI2 41. Diagnosis. Major ( Fig. 10 ): head, promesonotum, and gastral tergite I 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. 12–13 ommatidia; gastral tergite I punctate; propodeal spine almost absent. Minor ( Fig. 11 ): propodeal dorsum smooth and shiny; petiole and postpetiole without hairs; propodeal junction bluntly angulate; body reddish brown. Delete Queen ( Fig. 12 ). Head in full-face view almost as broad as long; lateral margin weakly convex, posterior margin shallowly concave, and posterolateral corner roundly convex; cephalic median furrow indistinct. Mandible short, subtriangular. Clypeus broad, with anterior margin weakly convex. Frontal lobe poorly developed, only partly covering antennal socket; frontal carina conspicuous, reaching level of anterior margin of eye. Eye larger than in worker, located at mid-length of head laterally; three ocelli present, located slightly above level of posterior margin of eye; distances between median ocellus and lateral ocelli almost as long as distance between lateral ocelli.Antenna 11-segmented with 2-segmented club; scape thin, clavate (its width at apex almost same as length of antennal segment X), and short (when laid backward reaching posterior one-third of head length). Mesosoma larger than head, in lateral view stout, with weakly convex dorsal outline. Pronotum in dorsal view invisible, overhanging by mesoscutum; in lateral view subquadrate; mesoscutum distinctly longer than broad, anterior margin roundly convex; mesoscutellum in dorsal view shorter than broad, anterior and posterior margin convex. Mesopleuron in profile clearly demarcated from lateral face of pronotum, mesoscutum, and metapleuron by distinct sutures; anepisternum clearly demarcated from katepisternum by deep oblique mesopleural sulcus; metapleuron clearly demarcated from lateral face of propodeum; metanotum short (just a ‘narrow’ band). Metanotal groove distinct. Propodeum in profile view distinctly lower than promesonotum, with its dorsal outline almost straight; propodeal spine in profile short and subtriangular, shorter than its base. Petiole with long anterior peduncle; petiolar node in profile shorter than high. Postpetiole roundly convex in dorsal outline. Gaster large; its anterior margin concave in dorsal view. Posterior one-third of head dorsum with fine transvers striation,anterior two thirds with fine longitudinal striation;lateral face slightly shiny; mandible smooth and shiny; clypeus smooth and shiny in median portion; antennal scape somewhat smooth and shiny. Pronotum punctate, but punctation weaker than on mesopleuron and propodeum; mesonotum punctate; mesopleuron punctate; mesopleuron largely smooth and shiny; metapleuron entirely punctate; propodeum entirely punctate. Petiole and postpetiole punctate. Gastral tergite I superficially reticulate with smooth and shiny interspaces. Dorsum of head with dense very short hairs over surface; vertex with a pair of erect hairs; frons sparse erect hairs; mandible with sparse decumbent hairs; antennal scape covered with dense decumbent hairs; pronotum without hairs; mesosomal dorsum with sparse erect hairs; legs without hairs; petiole with 2 erect hairs in the middle of peak; postpetiole without erect hairs; gastral tergite I with few erect hairs. Body dark brown to reddish brown; gaster dark brown to black; antenna and legs reddish brown. Habitat. This species inhabits both disturbed and primary forests, ranging from lowland to highland areas ( 100–1000 m a.s.l.). Most colonies were collected from dead logs on the forest floor, while one colony (TH20-WJT-21) was collected from a dead part (stem) of a living tree. FIGURE 10. Carebara pygmaea , non-type major worker (THNHM-I-2013-05969). A, Body in profile view; B, head in fullface view; C, body in dorsal view. FIGURE 11. Carebara pygmaea , non-type minor worker (THNHM-I-2013-05970). A, Body in profile view; B, head in fullface view; C, body in dorsal view. Distribution. Thailand ( Chiang Rai , Tak , Kanchanaburi , Petchaburi, Nakhon Nayok , Chonburi , Rayong , Chachoengsao , Chanthaburi , Surat Thani , Nakhon Si Thammarat , and Trang Provinces, Fig. 13 ). Remarks. It is most similar to Carebara rubra (F. Smith, 1860) and Carebara transversalis (F. Smith, 1860) in lacking erect hairs on the head, mesosoma, and gastral tergite I (except for 3 pairs on the frontal carinae). However, this species can be separated from the latter two by: short propodeal spine, shorter than its base or almost absent (relatively longer than their base in the letter two), and punctate lateral face of pronotum, petiolar node, and postpetiole (slightly smooth and shiny in the latter two). Pronotum of the holotype major worker is rather smooth but it is weakly punctate in the Thai population. However, we did not find any important differentiate between the Thai specimens from the holotype . Thus, we identified Thai specimens as C. pygmaea . The pronotum of the type of C . pygmaea simalurensis is clearly smooth and shiny and the head has sparse short erect hairs. This species seems different from the holotype of C. pygmaea . We did not examine a type specimen of C . pygmaea simalurensis directly, thus, for the time being, we did not review the status of this subspecies.