Carebara lithophila Yamane, Sasaki et Hosokawa 2025, sp. n.

Carebara lithophila Yamane, Sasaki et Hosokawa, sp. n. https://zoobank.org/NomenclaturalActs/ E31139EA-A4CA-41DD-89EC-0580F516040E Figs 1–3, 4 A,C,D TYPE MATERIAL. Holotype – major worker, Agarisaki, Yonaguni-jima, Yaeyama Islands, Southern Ryukyus, Japan, 11.iii.2020, nest under big stone, Sk. Yamane leg. (deposited in SKYC, Kitakyushu Museum of Natural History and Human History, Japan). Paratypes: all specimens originated from the same colony as the holotype. Four majors and nine minors collected by Sk. Yamane (SKYC), 2 majors and 2 minors collected by F. Ito (Kagawa Univ.), and 5 majors and 6 minors collected by R. Hosokawa (Kagawa Univ.). WORKER DIAGNOSIS. Antenna with 7 flagellomeres (9 antennomeres); mandible with 5 teeth, of which basal tooth low and reduced. Major worker. Body 2.5–2.7 mm in total length; head width 0.58–0.59 mm. In profile view dorsal (‘anterior’) outline of head nearly straight. Vertex with pair of well-developed horns that are longer than their basal width and connected with complete carina. Eye small with one or two indistinct ommatidia. Anterior ocellus always present, but sometimes ill developed. Dorsum of mesosoma essentially smooth and shiny. Metapleural gland bulla entirely sculptured. Propodeal spine absent. Propodeal lobe with evenly curved posterior margin. Petiolar node in profile subtriangular, narrowed apicad. Minor worker. Body 0.85–1.00 mm in total length; head width 0.27–0.29 mm. Dorsum of head only superficially punctate and shiny. Obsolete eye generally present. Pronotum with scattered shallow punctation but smooth and shiny. Propodeal spine absent. Petiolar node in profile low, broadly rounded apically. Body yellow. MAJOR WORKER DESCRIPTION (Fig. 1, 2, Fig. 4A,C,D). Measurements (in mm) and indices (n=5). TL 2.5–2.7, HW 0.58–0.59, HL 0.78–0.79, SL 0.28–0.30, PrW 0.38–0.40, PtW 0.17–0.18, PtL 0.09-1.00, PtH 0.20–0.22, PptW 0.19–0.20, PptL 0.11, PptH 0.13–0.14. CI 73.4–74.7, SI 47.5–51.7. Head in full-face view distinctly longer than broad, with deeply concave posterior margin, nearly parallel lateral margins and pair of well-developed horns near posterolateral corners of head; horns widely separated from each other (distance 0.35– 0.38 mm), connected with transverse carina, and tapered apicad. Anterior ocellus always present, but sometimes obsolete. Weak mid-cranial line (often obsolete) starting at anterior ocellus and reaching posterior end of unsculptured triangular area of frons behind clypeus. Frontal carina very short, extending slightly beyond level of posterior margin of torulus; frontal lobe broad; distance between frontal lobes subequal to lobe width. Clypeus roughly divided into sloping anterior disc + transverse lateral areas and posterior narrow area, the last being flanked by frontal carinae, and posteriorly not clearly demarcated from frons by suture; anterior disc roughly trapezoidal, almost flat, flanked by strong lateral carinae that are divergent apicad, anteriorly shallowly convex; anterior margin of the disc medially straight to shallowly concave. Mandible triangular, stout, with five teeth on masticatory margin; size of teeth decreasing from apical to basal tooth, the last being low and often obsolete. With head in profile view, dorsal (‘anterior’) outline almost flat and ventral (‘posterior’) outline more convex. Eye small, composed of one or two indistinct ommatidia, located distinctly anteriorly on gena at 1/3 length. Antenna with 7 flagellomeres (9 antennomeres) with basal segments of flagellum poorly differentiated; scape short, when laid straight back from its insertion not attaining midlength of cranium, in frontal view with its 2/5 very narrow and apical 3/5 broad and spindle-shaped; pedicel longer than preapical flagellomere; apical flagellomere very long but shorter than remaining flagellomeres combined, apically pointed. With mesosoma in dorsal view, pronotum largest, round, with posterior margin broadly concave; promesonotal suture well defined; mesoscutum broader than long, narrower than pronotum, narrowed posteriad; mesoscutellum weakly differentiated from mesoscutum, narrower than the latter, transverse; metanotal groove sharply defined; propodeal dorsum slightly longer than broad, widened posteriad, triangularly concave; declivity laterally margined with carinae. With mesosoma in profile view, promesonotum forming single dome but divided into two sclerites by promesonotal suture, roundly convex, not smoothly continuous to dorsal outline of propodeum. Pronotum large, posteriorly with small dent at mid-height, ventrally carinate. Mesopleuron clearly demarcated from pronotum but vaguely from mesonotum. Metapleuron fused with propodeum in lower portion; metathoracic spiracle much smaller than propodeal spiracle, often obscure. Propodeum with almost straight dorsal outline; its posterolateral corner roundly angulate; posterior margin shallowly concave; propodeal lobe posteriorly evenly curved; spiracle located near center of lateral face of propodeum. With waist in dorsal view, petiolar node broader than long, with straight anterior and convex lateral margins; postpetiole only slightly broader than petiole, broader than long, with straight anterior and convex lateral margins. With waist in profile view, petiole with distinct anterior peduncle; petiolar node with long steep anterior slope, short dorsum and gently sloping posterior slope that is longer than dorsum; ventral margin of petiole straight, without subpetiolar process. Postpetiole lower than petiole, with round apex and long posterior slope that is not clearly separated from dorsum. Gaster voluminous, much larger than head, mesosoma and waist combined; cinctus on gastral tergite 1 (abdominal tergite 4) well defined, formed by chain of elongate punctures. Legs relatively short; femora basally distinctly flattened; tibiae each shorter than femora, widened apicad. Body extensively shiny. Anterior half of head dorsum densely with longitudinal striation and matt; posterior half with punctation and rather shiny. Area in front of horn and around anterior ocellus irregularly sculptured. Areas in front of and behind carina connecting horns with fine irregular transverse striae; occiput smooth and shiny. Temple and gena smooth and shiny in posterior 2/3, but space between eye and mandibular base densely longitudinally striate (not reticulate) and matt. Venter of head extensively smooth except in anterolateral area striate. Anterior area of clypeus densely sculptured and matt. Mandible entirely smooth. Antenna and legs predominantly smooth and shiny. Dorsum of mesosoma largely smooth to very superficially sculptured and shiny; pronotum with irregular striation along its posterior margin. Lateral face of pronotum smooth, with median zone puncto-striate. Mesopleuron extensively smooth, but anteroventrally and posteriorly sculptured. Metapleuron and lateral face of propodeum extensively striate; metapleural gland bulla entirely sculptured. Dorsum of waist smooth; remaining parts sculptured. Gastral tergites and sternites essentially smooth and shiny, with sparse piligerous punctures; pretergite of gastral segment 1 minutely sculptured and matt. Antenna and legs predominantly smooth and shiny; coxae and trochanters irregularly sculptured. Head dorsum with suberect hairs of variable length; with head in full-face view its lateral margin posteriorly with sparse long hairs, anteriorly without erect hairs; venter of head with relatively long appressed hairs and sparse erect hairs. Mandible with sparse minute hairs only, but several longer decumbent hairs present along masticatory margin. Clypeus essentially glabrous. Antenna covered with suberect hairs. Mesosomal dorsum with sparse erect/suberect hairs. Waist dorsally with long erect hairs. Dorsum of gastral tergite 1 with erect/suberect hairs of variable length; tergites 2–4 glabrous except for apical zones, which bear long erect hairs; sternite 1 with sparse erect hairs; sternites 2–4 with erect hairs only apically; apical tergite and sternite with erect hairs. Coxae with suberect hairs; femora basally with relatively short suberect hairs on ventral face; fore- and hindtibiae with nearappressed hairs on dorsal (outer) faces, and longer slanting hairs in apical 1/3 of ventral (inner) face; midtibia with longer, often slanting hairs on dorsal face; all tibiae with longer suberect hairs on apicoventral areas; tarsi covered with numerous suberect hairs. Body entirely yellowish brown; clypeus and mandible slightly darker. MINOR WORKER DESCRIPTION (Fig. 3). Measurements (in mm) and indices (n=5). TL 0.85–1.00, HW 0.27–0.29, HL 0.33–0.36, SL 0.18–0.20, PrW 0.18, PtW 0.08–0.09, PtL 0.05–0.07, PtH 0.09, PptW 0.09, PptL 0.07, PptH 0.07. CI 80.0–82.4, SI 64.3–67.9. Head in full-face view longer than broad, with posterior margin very shallowly emarginate, lateral margins parallel and posterolateral corner roundly angulate; occipital margin not carinate. With head in profile view, dorsal (‘anterior’) and ventral (‘posterior’) margins straight and almost parallel. Frontal carinae very short and parallel; frontal lobe small, only partly covering antennal socket. Clypeus composed of posterior small area flanked by frontal lobes and anterior large transverse area bridged by narrow median disc with posterior area, anteriorly shallowly convex, with anterior margin curved. Mandible elongate-triangular with five teeth; apical tooth largest and basal one very small. Eye very small, sometimes vestigial, located anterior to midlength of cranium. Antenna with 7 flagellomeres (9-antennomeres); scape when laid straight back from its insertion reaching midlength of cranium, with apical 3/5 distinctly widened and flattened: pedicel relatively large, only slightly shorter than flagellomeres 1-5 that are each very small and broader than long; preapical flagellomere globular, slightly longer than broad; apical flagellomere large, parallel-sided in basal half, then narrowed