Brachyponera troglomorpha Duanchay et Jaitrong, 2024

Brachyponera troglomorpha Duanchay et Jaitrong , sp. n.

https://zoobank.org/NomenclaturalActs/ 71D26A37-2C8A-49F2-AB92-12CA7F3E7C3A

Fig. 2 View Fig 2

TYPE MATERIAL. Holotype – worker (THNHM-I-00029190, THNHM), Thailand: Nan Province, Muang District, Pha Sing Subdistrict, Ban Pha Tup , Bow Nam Thip Cave , 19.V 2018, S. Jantarit leg., SJ190518-01 . Paratypes: 4 workers (THNHM-I-00029191 to THNHM-I-00029194), same data as holotype .

DESCRIPTION. Worker. Medium size (head width 0.74–0.78 mm); body reddish brown; eye large, with 31–33 ommatidia (with 7–8 ommatidia along longest axis); mandible with basal pit; antennal scape relatively short compared with head width (SI 93–100); promesonotum distinctly convex to form a dome; propodeum in profile extremely located lower than promesonotum, straight, short, slightly shorter than length of propodeal declivity; body entirely superficially micropunctate and covered with short white pubescence mixed with sparse short erect hairs.

Head: in full-face view, longer than broad, broadened medially; lateral margin weakly convex; posterior margin almost straight; posterolateral corner of head roundly convex. Mandibles subtriangular and with basal pit; masticatory margin with large apical tooth followed by a series of seven distinct teeth of gradually reducing size to basal tooth. Clypeus broad its anterior margin roundly convex. Antenna scape relatively short compared with head width, when folded back in full-face view slightly extending beyond posterior margin of head; antennal segment II slightly longer broad; segments III–VII each almost as long as broad; segment XII slightly longer than X+XI. Frontal carinae in full-face view distinct, reaching anterior to medlength of head. Frontal lobe broad, flat, its outer margin distinct convex, coving antennal socket. Eye in profile located close to mandibular base, round, relatively large compared with maximum width of antennal scape, weakly convex, ca. 31–33 ommatidia (with 7–8 ommatidia along longest axis); in full-face view, outer margin of eye reaching lateral margin of head.

Mesosoma: in profile promesonotum distinctly convex to form a dome; in dorsal view, pronotum almost as long as broad and clearly broader than mesonotum and propodeum; mesopleuron clearly shorter than high, clearly demarcated from pronotum, mesonotum, and metapleuron by deep suture; metapleuron not clearly demarcated from lateral face of propodeum. Propodeum in profile located extremely lower than promesonotum, its dorsal outline almost straight and shorter than length of propodeal declivity; propodeal dorsum round into propodeal declivity; propodeal declivity shallowly concave.

Petiole sessile; in profile petiolar node subtriangular, clearly shorter than high, its anterior face weakly convex, while posterior face flat; petiolar height ≥ twice as long as length of propodeal dorsum.

Body entirely finely superficially micropunctate, except for mesopleuron and metapleuron smooth and shiny; antenna and legs micropunctate; mandible rather smooth and shiny. Antennal scape and legs shiny.

Body entirely covered with short white pubescence mixed with sparse short erect hairs; erect hairs on propodeal dorsum and petiole absent. Antenna and legs without erect hairs. Body entirely yellowish brown. Antennal scape yellowish brown to reddish brown, flagellum of antenna yellowish brown. Legs yellow.

MEASUREMENTS AND INDICES. Holotype: TL 3.69, ED 0.12, HL 0.84, HW 0.74, SL 0.69, ML 1.02 , MW 0.53, PL 0.25, PH 0.52, CI 88, OI 16, SI 133 , PI 48 . Paratypes (n = 4): TL 3.61–4.00, ED 0.10–0.14, HL 0.80–0.90, HW 0.74–0.78, SL 0.69–0.78, ML 1.02 – 1.15 , MW 0.50–0.59, PL 0.24–0.25, PH 0.52–0.62, CI 87– 96, OI 14–18, SI 93–100 , PI 40–48 .

DIAGNOSIS. Brachyponera troglomorpha sp. n. is most similar to B. kumtongi sp. n. in having a reddish-brown body and a dome-like promesonotum when seen in profile. See “remarks” under B. kumtongi . This new species is also similar to B. jerdonii and B. arcuata in general appearance that they share the large eye (with over 7 ommatidia along longest axis) and reddish-brown body. However, it can be distinguished from the latter two by propodeal dorsum almost straight, shorter than length of propodeal declivity (weakly to distinctly convex, almost as long as or longer than length of propodeal declivity in the latter two). The eye of B. troglomorpha sp. n. is smaller than that of B. jerdonii (with 7–8 ommatidia along longest axis in B. troglomorpha ; ca. 9–10 ommatidia along longest axis in B. jerdonii ). The new species is easily distinguished from B. arcuata by 1) head, pronotum, and gastral tergite with short erect hairs (clearly absent in B. arcuata ); 2) frontal carina relatively long, reaching anterior to medlength of head (short, reaching level posterior margin of eye in B. arcuata ); 3) body colour paler (darker in B. arcuata , see Figs. 2A View Fig 2 and 3L View Fig 3 for comparison).

HABITAT. This new species was collected from a cave in northern Thailand. The workers were working on the ground at dark zoon of the cave. DISTRIBUTION. Nan Province ( Fig. 4 View Fig 4 ). ETYMOLOGY. The specific name refers to a unique element of subterranean life, like continual darkness.