Carebara pygmaea (Emery, 1887)

Jaitrong, W., Pitaktunsakul, P. & Jantarit, S., 2021, A new species of the genus Carebara Westwood, 1840 (Hymenoptera: Formicidae: Myrmecinae) inhabits a cave in Thailand, Far Eastern Entomologist 425, pp. 7-20 : 13-17

Carebara pygmaea (Emery, 1887)

Figs 3 , 4

Pheidologeton pygmaeus Emery, 1887: 465 (type locality: Indonesia, Ternate Island);

Ettershank, 1966: 119.

Pheidologeton (Aneleus) pygmaeus: Emery, 1900: 327 .

Aneleus pygmaeus: Emery, 1924: 214 .

Carebara pygmaeus: Fischer et al., 2014: 72 ; Khachonpisitsak et al., 2020: 82.

Pheidologeton pygmaeus var. albipes Emery, 1893: 266 (type locality: the Philippines);

Ettershank, 1966: 118. Junior synonym of pygmeae (Fischer et al., 2014: 72).

Aneleus pygmaeus var. albipes: Emery, 1924: 214 .

Pheidologeton (Aneleus) pygmaeus var. bugnioni Forel, 1915: 28 (type locality: Sri

Lanka); Ettershank, 1966: 118. Junior synonym of pygmeae (Fischer et al., 2014: 72).

Aneleus pygmaeus var. bugnioni: Emery, 1924: 214 .

Pheidologeton (Aneleus) pygmaeus var. simalurensis Forel, 1915: 27 (type locality:

Indonesia, Sumatra). Junior synonym of pygmeae (Fischer et al., 2014: 72).

Aneleus pygmaeus var. simalurensis: Emery, 1924: 214 .

Oligomyrmex simalurensis: Ettershank, 1966: 124 .

Carebara pygmaeus var. simalurensis: Fernández, 2004: 235 .

MATERIAL EXAMINED. Northern Thailand: Chiang Rai Prov., Mae Fa Luang Dist .,

Mae Fa Luang Subdist., Doi Tung, 589 m a.s.l., 20º16ˈ 19ˈˈN, 99º49ˈ19ˈˈE, 22.X.2018, W.

Jaitrong leg., WJT221018-43 ( THNHM). Western Thailand: Tak Prov., Umphang Dist .,

Thung Yai Naresuan East W.S., Thung Na Noi Station, 20.II.2015, W. Jaitrong leg., TH15-

WJT-411 ( THNHM); Kanchanaburi Prov., Thong Pha Phum Dist., Maeklong Watershed

Research Station, 29.XI.2003, Sk. Yamane leg., TH03-SKY-145 ( SKYC, THNHM).

Eastern Thailand: Chonburi Prov., Khao Ang Reu Nai W.S., Ang Phaknam Station , dry evergreen forest, 3.IV.2004, W. Jaitrong leg., WJT04-E006 ( THNHM) ; Rayong Prov., Khao

Ang Reu Nai W.S., Siraman Station, dry evergreen forest, 5.IV.2004, W. Jaitrong leg.,

WJT04-E028 ( THNHM); Chachoengsao Prov., Thatha Keab Dist., Khao Ang Reu Nai W.S.,

Bo Thong Waterfall, 27.IV.2003, W. Jaitrong leg., WJT03-TH-5 ( THNHM); Chanthaburi

Prov., Pheao N.P., Troknong Waterfall, 23.XI.2003, W. Jaitrong leg., TH03-WJT-580

( THNHM); same locality, date and collector, TH03-WJT-563 ( THNHM); Chanthaburi Prov.,

Soi Dao Dist., Khao Soi Dai W.S., Head Quarter, 14.IV.2008, W. Jaitrong leg., WJT08-E062

( THNHM); Chanthaburi Prov., Pong Nam Ron Dist. , Khlong Tab Mak Waterfall, 18. V.2008,

W. Jaitrong leg., WJT08-E181 ( THNHM). Southern Thailand: Surat Thani Prov., Tha

Chang Dist., Tha Chang Subdist., evergreen forest, 27.II.2020, W. Jaitrong leg., TH20-WJT-

21 ( THNHM); Nakhon Si Thammarat Prov., Sichon Dist., Khao Nan N.P., Yod Nam

Waterfall, 239 m a.s.l., 11.XII.2007, W. Jaitrong leg., WJT07-TH1886 ( THNHM); Trang

Prov., Nayong Dist., Khao Chong B.G., 23.II.2020, W. Jaitrong leg., TH20-WJT-02

( THNHM).

MEASUREMENTS. Major worker (n = 10): TL 4.13–4.16, HL 1.19–1.22, HW 1.02–

1.06, SL 0.53–0.56, ML 0.89–0.96, MW 0.59–0.63, PL 0.33–0.35, PH 0.26–0.30, DPW 0.26,

Minor worker (n = 10): TL 2.02–2.08, HL 0.46–0.50, HW 0.46–0.48, SL 0.36–0.40,

ML 0.50–0.53, MW 0.23–0.26, PL 0.20–0.23, PH 0.17, DPW 0.10, CI 93–100, SI 79–86,

PI 1 120–140, PI 2 43–50.

Major worker ( Fig. 3A–C ). Head, in full-face view, almost as long as broad, lateral margin weakly convex, posterior cephalic margin shallowly concave, and posterolateral corner roundly convex; cephalic median furrow indistinct; in dorsal view, posterior one fourth of head with fine transverse striation, anterior three fourth of head with fine longitudinal striation; lateral (area below eye) face of head punctate (in some specimens slightly shiny); head body in profile; B – dorsal view of body; C – head in full-face view.

with three pairs of erect hairs on frontal carinae and dense very short hairs over surface,

vertex and frons without erect hairs; mandible short, subtriangular, smooth and shiny;

mandible with sparse decumbent hairs; anterior clypeal margin weakly convex; median portion of clypeus smooth and shiny; frontal lobe poorly developed, only partly covering antennal socket; frontal carina conspicuous, reaching level of anterior margin of eye; eye relatively small, with 12–13 ommatidia, located at anterior one third of head length laterally;

antenna 11-segmented with 2-segmented club; antennal scape thin (clavate, its apical portion almost as long as antennal segments X) and short, when laid backward reaching posterior one third of head length; scape somewhat smooth and shiny, covered with dense decumbent hairs.

Mesosoma smaller than head and gaster; promesonotum strongly convex to form a dome, mesosonotum slope to metanotal groove; promesonotal suture indistinct; pronotum punctate; mesonotum punctate; mesopleuron punctate, clearly demarcated from metapleuron by deep groove; metanotal groove distinct; propodeal spine, in profile, short and subtriangular,

shorter than its base; in profile view, propodeum distinctly lower than promesonotum, its dorsal outline almost straight; metapleuron and propodeum entirely punctate; mesosoma without hairs; legs smooth and shiny without hairs; punctation on pronotum weaker than on mesopleuron and propodeum.

Petiole, in profile, with long anterior pedicel, punctate and without hairs; petiolar node,

in profile, shorter than high, smooth and shiny, without hairs; postpetiole round, its dorsal outline convex, punctate, without hairs.

Gaster slightly smaller than head and elliptical; gastral tergite I superficially reticulate with smooth and shiny interspaces, without hairs; anterior margin of gastral tergite I concave.

Body reddish brown to dark brown; gaster dark brown; antenna and legs reddish brown.

Minor worker ( Fig. 4A–C ). Head, in full-face view, as long broad, lateral margin weakly convex and posterior cephalic margin weakly concave; head entirely smooth and shiny;

dorsum of head entirely covered with dense short decumbent hairs, and a pair of erect hairs on frontal carinae; mandible short, subtriangular, smooth and shiny; clypeus entirely smooth and shiny, its anterior clypeal margin roundly convex; frontal lobe poorly developed, only partly covering antennal socket; frontal carina inconspicuous; eye relatively small, with one ommatidium, located at anterior one fourth of head length laterally; antenna 11-segmented with 2-segmented club; antennal scape thin (clavate, its apical portion almost as broad as antennal segments X), when laid backward almost reaching posterolateral corner of head;

scape somewhat smooth and shiny, without hairs.

Promesonotum strongly convex to form a dome, mesonotum slope to metanotal groove,

with dense short decumbent hairs; promesonotal suture absent, promesonotum entirely smooth and shiny; mesopleuron finely punctate, clearly demarcated from metapleuron by deep groove; metanotal groove distinct; metapleuron punctate, not demarcated with lateral face of propodeum; propodeal spine absent, in profile view, propodeum distinctly lower than promesonotum, its dorsal outline weakly convex; propodeal junction convex; declivity of propodeum shallowly concave, marginated laterally by thin rim; dorsum of propodeum smooth and shiny, its lateral face punctate; mesosoma without erect hairs; legs smooth and shiny, without hairs.

Petiole, in profile, with long anterior pedicel, micropunctate and without hairs; petiolar node, in profile, shorter than high, convex dorsal outline, smooth and shiny, without hairs;

postpetiole in profile view, round, convex dorsal outline, smooth and shiny, without hairs.

Gastral tergite I smooth and shiny, and covered with dense short decumbent hairs but without erect hairs; anterior margin of gastral tergite I concave. Body reddish brown to dark brown.

DIAGNOSIS. Carebara pygmaea is most similar to Carebara rubra (Smith, 1860) and

Carebara transversalis (Smith, 1860) in lacking erect hairs on head, mesosoma, and gastral tergite I (except 3 pairs on frontal carinae). However, this species can be separated from the latter two by: the shot 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).

body in profile; B – dorsal view of body; C – head in full-face view.

HABITAT. This species inhabits both disturbed and primary forests and from lowlands to highlands (100–1000 m a.s.l.). Most colonies were collected from dead logs on forest floor. One colony (TH20-WJT-21) was collected from the dead part (stem) of a living tree.

DISTRIBUTION. Sri Lanka, Laos (Vientiane Province) , Thailand (Chiang Rai, Tak,

Kanchanaburi, Chonburi, Rayong, Chachoengsao, Chanthaburi, Surat Thani, Nakhon Si

Thammarat, and Trang Provinces), Malaysia (Borneo), Indonesia (Sulawesi, Sumatra, and

Ternate), and the Philippines.

Figures

Fig. 3. Carebara pygmaea, major worker (THNHM-I2013-05969 [= TH03-SK-145]). A –

Fig. 4. Carebara pygmaea, minor worker (THNHM-I2013-05970 [= TH03-SK-145]). A –