Myrmecina laevidorsa Gu & Chen, 2025

Gu, Zhuojian, Zhang, Chen, Du, Congcong & Chen, Zhilin, 2025, Synopsis of the ant genus Myrmecina Curtis, 1829 from China (Hymenoptera, Formicidae, Myrmicinae), with description of eleven new species, Deutsche Entomologische Zeitschrift 72 (2), pp. 395-448 : 395-448

Myrmecina laevidorsa Gu & Chen sp. nov.

Fig. 42

Material examined.

Holotype. • worker, Maoershan , Guangxi, China, 26.8810°N, 110.4146°E, 1551 m, secondary forest, leaf litter, 09. VIII. 2020, Zhilin Chen, GXNU 20002688 [ GXNU] . Paratypes. • 3 workers, with the same collection data as the holotype [ 2 worker, GXNU; 1 worker, IZCAS] .

Diagnostic features.

(1) Eyes small, composed of 4–6 ommatidia; (2) densely punctate over most of head surface except for smooth and shining medial frons, clypeus and lateroventral portions; (3) mesosomal dorsum completely smooth and shining; (4) propodeal spiracle unusually large, diameter approximately twice as its distance to propodeal declivity; (5) propodeal spines slender, posteriorly directed, length about 1 / 3 the distance between their apices; (6) predominantly yellowish-brown body, with dark brown posterior head and mid-gaster.

Notes.

M. laevidorsa Gu & Chen , sp. nov is characterized by its completely smooth and shining mesosomal dorsum, a key diagnostic feature that distinguishes it from closely related taxa. It most closely resembles M. breviata but can be readily distinguished by the following combination of characters: (1) the head of M. laevidorsa Gu & Chen , sp. nov. is rectangular, with nearly parallel lateral margins and medially concave posterior margin, while the head of M. breviata is subquadrate, with convex lateral margins and straight to weakly convex posterior margin; (2) the cephalic sculpture of M. laevidorsa Gu & Chen , sp. nov. is densely punctate except for smooth medial frons and clypeus, whereas M. breviata exhibits longitudinal rugae across the entire dorsum of head; (3) the mesosomal dorsum of M. laevidorsa Gu & Chen , sp. nov. is smooth and shining, contrasting with M. breviata ’ s weakly carinate pronotum and mesonotum. (4) the propodeal spiracle of M. laevidorsa Gu & Chen , sp. nov. is exceptionally large (diameter twice its distance to declivity), compared to M. breviata ’ s smaller spiracle (diameter ≤ 1 / 6 × the distance); (5) the postpetiole of M. laevidorsa Gu & Chen , sp. nov. is rectangular, with distinct anteroventral corners, versus M. breviata ’ s more globular postpetiole with less-defined corners; (6) the eyes of M. laevidorsa Gu & Chen , sp. nov. extremely reduced (4–6 ommatidia) compared to M. breviata (typically 10–12 ommatidia).

Worker measurements.

(N = 3). HL 0.44–0.46, HW 0.40–0.42, CI 90–93, SL 0.31–0.35, SI 76–78, ED 0.02–0.03, MSL 0.52–0.54, PW 0.27–0.29, PL 0.13–0.15, PH 0.14–0.16, DPW 0.12–0.14, LPI 106–108, DPI 92–96, GL 0.64–0.67, TL 2.08–2.12.

Worker description.

Head. In full-face view, head distinctly rectangular, longer than broad, lateral margins nearly parallel, posterior margin medially concave, posterolateral corners rounded. Mandibular masticatory margin bearing 8–9 teeth: apical two teeth 1–2 robust, teeth 3–6 small and uniform in size, aligned on the same line as the major teeth; teeth 7–8 slightly larger than 3–6 but lower in height; basal tooth indistinct or occasionally absent. Clypeal anterior margin nearly straight, lacking a median denticle. Frontal lobes thin, subtranslucent, and slightly laterally expanded. Antennae 12 - segmented, scapes barely reaching posterolateral corners of head. Eyes small, composed of 4–6 ommatidia. Mesosoma. In lateral view, dorsal outline of mesosoma weakly convex; eumetanotal spines inconspicuous. Propodeal spines slightly longer than their basal width, directed posteriorly. Propodeal spiracle large, circular, diameter twice as its distance to propodeal declivity. In dorsal view, anterior pronotal margin evenly convex, humeral corners prominent; pronotum slightly broader anteriorly than posteriorly; mesonotum abruptly constricted posteriorly. Propodeum with a transverse carina anteriorly; propodeal spines slender, directed posteriorly, length approximately 1 / 3 the distance between their apices. Metasoma. In lateral view, petiole slightly higher than long, dorsum with a triangular projection; ventral margin almost straight, anteroventral corner rounded. Postpetiole rectangular, anteroventral corner angulate, posteroventral corner angular; gaster ovoid. In dorsal view, petiolar dorsum carinate; postpetiole broader anteriorly, with distinct rounded anterodorsal corners; gaster with prominent anterolateral corners. Sculpture. Mandibles, clypeus, and median frons smooth and shining; remainder of head densely punctate, except lateroventral portions smooth and shining. Mesopleura with shallow puncta and weak rugae; rest of mesosoma dorsally and laterally smooth and shining. Petiole laterally with 2–3 weak carinae. Postpetiole anteriorly smooth and shining, posteriorly with longitudinal rugae; gaster entirely smooth, except for short basal striae near insertion. Pilosity and pubescence. Body densely covered with short erect hairs; pubescence absents, except on antennal club. Coloration. Body predominantly yellowish-brown; posterior head and mid-gaster dark brown. Mandibles and appendages yellow.

Etymology.

The specific epithet “ laevidorsa ” is a Latin compound adjective derived from “ laevis ” (smooth) and “ dorsum ” (back), referring to the characteristically smooth and unsculptured dorsal surface of the mesosoma, a key diagnostic feature distinguishing this species from its congeners.

Distribution.

Guangxi.

Figures

Figure 42. Myrmecina laevidorsa Gu & Chen, sp. nov. A. Head in full-face view; B. Petiole in lateral view; C. Body in dorsal view; D. Body in lateral view.