Carebara pygmaea
Creators: name: Wimolsuthikul, Chaipat
name: Yamane, Seiki
name: Samung, Yudthana
name: Jaitrong, Weeyawat
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Formicidae
Carebara
Carebara pygmaea

description: Carebara pygmaea species group
Diagnosis. Dimorphic. Major. Frons with longitudinal striation; posterior portion of head in full-face view usually with transverse striation (except for C. bokorensis lacking this striation); vertex without a pair of horns; frontal carinae with three pairs of erect hairs; mandible short, subtriangular, masticatory margin with five teeth (including large apical tooth); promesonotum in profile view distinctly convex to form a dome; promesonotal suture indistinct; metanotal groove present; propodeum distinctly lower than promesonotum; propodeal spine short, usually shorter than width at base; petiole in profile, with long anterior peduncle; postpetiole clearly shorter than petiole; gastral tergite I clearly larger than remaining segments combined. Minor. Head small, smooth and shiny; mandible relatively short, subtriangular, masticatory margin with five teeth (including large apical tooth); eye very small, present as a dot; promesonotum in profile view convex, smooth and shiny; promesonotal suture absent; metanotal groove distinct; propodeal spine absent; petiole with long anterior peduncle; postpetiole clearly shorter than petiole; gastral tergite I clearly larger than remaining segments combined. Ergatoid queen. Morphological character is similar to major worker in having large head but mesosoma is slightly larger than in major worker and ocelli are present.
We placed C. bokorensis under the C. pygmaea species group because almost all characters of the minor and the major workers agreed well with the characteristics of the species group. The body sculptures and the condition of the hairs can be used to distinguish the species within the species group. We have tried to extract DNA using dry specimens but were unsuccessful using the PCR process. In future work, DNA barcoding should help to distinguish members of the C. pygmaea species group when obtaining fresh specimens.
Currently, valid names included in the species group of Thailand. Carebara adisaki sp. nov.; C. parva sp. nov.; C. panhai Jaitrong, Pitaktunsakul & Jantarit, 2021; C. bokorensis Matsuura & Hosoishi, 2024; C. pygmaea (Emery, 1887); C. rubra (Smith, 1860), and C. transversalis (Smith, 1860).
Distribution. Sri Lanka, Laos, Cambodia, Thailand, Malaysia (Borneo), Indonesia (Ternate to Sumatra), and Philippines.
Key to Thai species of Carebara pygmaea species group based on major worker
1 In dorsal view, posterior half of head and entire gastral tergite I without both erect and decumbent hairs (Fig. 10A).................................................................................................... C. pygmaea
- In dorsal view, posterior half of head and entire gastral tergite I with dense or sparse erect or decumbent hairs (Figs. 1A, 3A, 6A, 8A)............................................................................................. 2
2 Posterior one-third of head in full-face view with dense foveae, without transverse striation (Fig. 1B); gastral tergite I punctate (Fig. 3C).................................................................................. C. bokorensis
- Posterior one-third of head in full-face view with transverse striation (Figs 4B, 6B, 8B); gastral tergite I smooth and shiny, at most weakly shagreened (Figs. 1C, 6C, 8C)................................................................. 3
3 Mesosomal dorsum with erect hairs (Fig. 6A)........................................................ C. panhai
- Mesosomal dorsum without erect hairs (Figs. 1A, 8A)........................................................ 4
4 Propodeal spines shorter than diameter of propodeal spiracle; first gastral tergite with erect hairs only along its posterior margin (Fig. 1A).............................................................................. C. adisaki sp. nov.
- Propodeal spine almost as long as or slightly longer than diameter of propodeal spiracle; entire first gastral tergite covered with erect hairs (Fig. 8A)...................................................................... C. parva sp. nov.
Key to Thai species of Carebara pygmaea species group based on minor worker
1 Propodeal dorsum entirely punctate (Fig. 5A, C)................................................... C. bokorensis
- Propodeal dorsum smooth and shiny (Figs. 2A, 7A, 9A, 11A).................................................. 2
2 Antennal scape not reaching posterior margin of head (Fig. 11B); hairs on pronotum shorter than diameter of eye (Fig. 11A)........................................................................................... C. pygmaea
- Antennal scape reaching or extending beyond posterior margin of head (Figs. 2B, 7B, 9B); hairs on pronotum longer than diameter of eye....................................................................................... 3
3 Propodeal junction roundly convex (Fig. 7A); antennal scape extending beyond posterior margin of head (Fig. 7B); dorsa of petiole and postpetiole each with 2–4 erect hairs (Fig. 7A).............................................. C. panhai
- Propodeal junction bluntly angulated (Figs. 2A, 9A); antennal scape reaching posterior margin of head (Figs. 2B, 9B); dorsa of petiole and postpetiole without erect hairs (Figs. 2A, 9A)...................................................... 4
4 Peduncle of petiole punctate; PI1 240–275; larger species (HW 0.43–0.46 mm in minor worker; 1.02–1.06 mm in major worker)............................................................................... C. adisaki sp. nov.
- Peduncle of petiole smooth and shiny; PI1 160–200; smaller species (HW 0.36–0.40 mm in minor worker; 0.79–0.83 mm in major worker)........................................................................... C. parva sp. nov.
description: Published as part of Wimolsuthikul, Chaipat, Yamane, Seiki, Samung, Yudthana & Jaitrong, Weeyawat, 2024, A revision of the Carebara pygmaea (Emery, 1887) species group (Hymenoptera: Formicidae) in Thailand, pp. 79-100 in Zootaxa 5481 (1) on pages 80-81, DOI: 10.11646/zootaxa.5481.1.5, http://zenodo.org/record/12742641