Carebara bokorensis Matsuura et Hosoishi, 2024

Matsuura, K., Hosoishi, S. & Sokh, H., 2024, A remarkable new species from the pygmaea species group of the genus Carebara Westwood, 1840 (Hymenoptera: Formicidae: Myrmicinae) from Cambodia, Far Eastern Entomologist 496, pp. 1-9 : 3-8

Carebara bokorensis Matsuura et Hosoishi , sp. n.

https://zoobank.org/NomenclaturalActs/ 9F1A8383-F9EE-4C51-9D94-BFD5AC006CA9

Figs 1 , 2

TYPE MATERIAL. Holotype (major worker): Cambodia: Bokor National Park , 663m alt., Kampot Province, N 10°36 E 104°06, 19. XII 2011, S. Hosoishi leg. SH11-Cam-55, decayed wood ( KUEC, collection code KUECCRB001) . Paratypes: same data as holotype, 2 major workers ( KUEC, collection code KUECCRB002, KUECCRB003) and 7 minor workers ( KUEC, collection code KUECCRB004, KUECCRB005, KUECCRB006, KUECCRB007, KUECCRB008, KUECCRB009, KUECCRB010) .

MEASUREMENTS. Holotype: TL 4.23, HL 0.97, HW 0.95, SL 0.44, ML 0.89, MW 0.42, PSL 0.17, PSD 0.07, PL 0.37, PH 0.35, DPW 0.18, CI 98, SI 47, PI1 106, PI2 48. Major worker (2 paratypes): TL 4.20–4.26, HL 0.92–1.25, HW 0.93– 1.02, SL 0.43–0.44, ML 0.89–0.92, MW 0.42–0.50, PSL 0.16–0.18, PSD 0.06–0.07 PL 0.34–0.37, PH 0.33–0.35, DPW 0.18–0.23, CI 98–101, SI 46–47, PI1 102–106, PI2 48–68. Minor worker (7 paratypes): TL 1.43–1.68, HL 0.33–0.41, HW 0.33– 0.38, SL 0.23–0.26, ML 0.39–0.45, MW 0.16–0.22, PSL 0.04–0.05, PSD 0.03– 0.04, PL 0.17–0.22, PH 0.14–0.15, DPW 0.08–0.10, CI 90–100, SI 67–71, PI1 117– 152, PI2 43–54.

DESCRIPTION. Dimorphism in worker caste. Major worker ( Fig. 1A–C ). Head, in full-face view, longer than wide, almost square (CI 98–101); posterior cephalic border deeply concave in the middle, posterolateral corners rounded, posterior lateral margins weakly convex; anterior clypeal margin entirely convex with median concave portion; frontal carinae inconspicuous; frontal triangle welldefined; mandibles short, almost triangular, masticatory margins with 5 teeth; ocelli present; eyes with around 12 ommatidia, situated at anterior one-third of lateral head; antennae 11-segmented with 2-segmented club; scapes thin and clavate, its apical portion same as antennal segment X, short, less than even half of head (SI 46–47).

Mesosoma smaller than head (HL 0.92–1.25, ML 0.89–0.92); promesonotum weakly convex in profile view; promesonotal suture present; scutellum present; mesopleuron clearly demarcated from pronotum and metapleuron by deep groove; metanotal groove present and separated by elevated band; metapleuron clearly demarcated from propodeum by deep groove; propodeum declining backwards; propodeal spiracle large ( PSD 0.06–0.07) and rounded; propodeal spines relatively long ( PSL 0.16–0.18); promesonotum distinctly higher than propodeum in profile view.

Petiole with long peduncle and high node, broader posteriorly in dorsal view; subpetiolar process absent; postpetiole rounded and shorter than petiole, lower than petiole node, trapezoidal dorsally.

Gastral tergite larger than remaining segments.

Sculptures: Head, posterior one-third of head punctate anterior two-third with longitudinal striation, lateral (area below eye) face striated; clypeus smooth and shiny medially, lateral sides longitudinally striated; frontal triangle smooth and shiny; frontal lobes with fine longitudinal striation; mandibles smooth and shiny; anterior dorsal surface of pronotum with faintly reticulations, smooth and shiny laterally; mesonotum punctate; mesopleuron separated by deep groove, both higher and lower mesopleuron smooth and shiny except for surroundings, under part of lower mesopleuron punctate; propodeum entirely punctate, but lower lateral face longitudinally striated; legs smooth and shiny; petiolar peduncle punctate, petiolar node micropunctate laterally, anterior declivity of node with reticulation; gastral tergite I smooth and shiny.

Pilosity: Head, in full-face view, posterior cephalic border with short decumbent hairs medially and long suberect hairs laterally, short decumbent hairs over surface; frontal carinae with 3 pairs of erect hairs; anterior margin of clypeus with 2 pairs of erect hairs; mandible, masticatory margins with long decumbent hairs, short decumbent hairs over surface; scapes with dense short decumbent hairs (slightly shorter than width of apical portion of scapes); mesosoma with erect hairs and decumbent hairs; legs with decumbent hairs; petiolar node and postpetiole with erect hairs; gastral tergite I with abundant short decumbent hairs and entirely scattered long erect hairs.

Color: Head and gaster dark brown; mesosoma, petiole and postpetiole reddish brown; antennae and legs yellowish brown.

Minor worker. ( Fig. 2A–C ). Head, in full-face view, wide same as long (CI 90–100), almost rectangle; posterior cephalic border slightly concave in the middle, posterolateral corners rounded, posterior lateral margins weakly convex; anterior clypeal margin convex, medially concave, frontal lobe present; frontal triangle welldefined; mandibles short, almost triangular, masticatory margins with 5 teeth; eyes relatively small, present as dots, situated at anterior one-fourth of lateral head; antennae 11-segmented with 2-segmented club; scapes thin and clavate, width of apical portion same as antennal segment X, relatively long, reaching posterior one-third of head length.

Promesonotum convex and entirely dome-shaped in profile view; promesonotal suture absent; mesopleuron clearly demarcated from metapleuron and pronotum; metanotal groove distinct; in profile view, declivity of propodeum with lamellae, maximum length of lamellae same as a diameter of propodeal spiracle; propodeal spines absent; propodeal spiracle large ( PSD 0.03–0.04) and rounded; dorsal outline of propodeum entirely rounded; mesosoma almost same length as head ( ML 0.39– 0.45, HL 0.33–0.41).

Petiole with relatively short peduncle and high node, spread posteriorly in dorsal view; subpetiolar process developed like triangle; postpetiole rounded and lower than petiolar node in profile view, rectangle in dorsal view; postpetiole smaller than petiole.

Gastral tergite larger than remaining segments.

Sculptures: Head, mandibles, promesonotum, legs, petiolar node and gaster smooth and shiny; mesopleuron, propodeum, petiolar peduncle punctate.

Pilosity: Head and mandibles with sparse decumbent hairs; scapes with sparse decumbent hairs (slightly shorter than width of apical portion of scapes); anterior margin of clypeus with 2 pairs of erect hairs; mesosoma, petiole and postpetiole without erect hairs; legs with decumbent hairs; gastral tergite I with decumbent hairs.

Color: Head, postpetiole and gaster brown; mesosoma, petiole, legs and antennae pale brown.

DIAGNOSIS. C. bokorensis sp. n. can be distinguished from the other species in the genus by the following characters: 11-segmented antennae, punctation on posterior surface of head, long petiolar pedicel, well-developed scutellum and metanotal groove separated by elevated band in the major worker subcaste; 11- segmented antennae, median concavity of anterior clypeal margin, entirely rounded promesonotum, short petiolar pedicel and presence of subpetiolar process in the minor worker subcaste.

REMARKS. Carebara bokorensis sp. n. shares most features except for promesonotal suture with the C. pygmaea species group. Jaitrong et al. (2021) defines promesonotal suture of major workers as indistinct in definition of C. pygmaea species group, and this is thought to be due to the exceptionally partial presence of promesonotal suture in C. panhai . This new species has a distinct promesonotal suture in major workers, but other morphological characters are consistent with the definition of the species group. Therefore, it is appropriate to include this new species in the species group. Furthermore, the major workers of this species also have scutellum, which is not found in the species group. Developed scutellum in major workers are found in some species such as C. oni (Terayama, 1996), C. phragmotica ( Fischer, Azorsa & Hita Garcia, 2015) and C. aberrans ( Santschi, 1937). Although it is beyond this study to infer it, such character state can be found in different lineages of Carebara .

The Carebara pygmaea species group includes five species, C. bokorensis sp. n., C. pygmaea, C. rubra, C. transversalis and C. panhai . The major workers of C. bokorensis are distinguished from the other four species in the species group by the presence of punctation on posterior surface of head, presence of scutellum and projection in the metanotal groove. The minor workers of C. bokorensis sp. n. are distinguished from the three species, C. pygmaea, C. rubra and C. panhai (minor worker of C. transversalis is unknown), in the species group by the presence of a well-developed subtriangular subpetiolar process and medial concavity of anterior clypeal margin.

HABITAT. Type series specimens were collected from decayed wood ( Fig. 3 ).

DISTRIBUTION. Cambodia (Bokor National Park, Kampot).

ETYMOLOGY. The species is named after the name of the Bokor National Park.

Figures

Fig. 1. A–C. Carebara bokorensis sp. n., holotype major worker (KUECCRB001). A – body in profile; B – dorsal view of body; C – head in full-face view.

Fig. 2. A–C. Carebara bokorensis sp. n., paratype minor worker (KUECCRB004). A – body in profile; B – dorsal view of body; C – head in full-face view.

Fig. 3. Carebara bokorensis sp. n. nesting in decayed wood (S. Hosoishi).