Myrmecina jiachengi 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 jiachengi Gu & Chen sp. nov.

Fig. 40

Material examined.

Holotype. • worker, Shifushi , Changanqu, Xian, Shaanxi, China, 34.0207°N, 108.7894°E, 5560 m, secondary forest, leaf litter, 10. VI. 2019, Jiacheng Zhang, GXNU 19400156 [ GXNU] . Paratypes. • 5 workers, with the same collection data as the holotype [ 4 worker, GXNU; 1 worker, IZCAS] .

Diagnostic features.

(1) Nearly the entire head (except smooth medial frons) and mesosoma with coarse reticulation, a unique feature among Chinese Myrmecina (which typically exhibit longitudinal striae, rugae, or smooth surfaces); (2) anterolateral clypeal projections and arcuately concave anterior clypeal margin with a median denticle; (3) conical anterior pronotal projection and stout propodeal spines (basal width> length), directed posterodorsally with upturned apices; (4) petiole much higher than long, with steep anterior face, concave posterior face, and a distinct subpetiolar process; (5) large eyes (> 20 ommatidia).

Notes.

M. jiachengi Gu & Chen , sp. nov. is unambiguously distinguished from all other Chinese Myrmecina species — which typically exhibit longitudinal striae, rugae, or smooth surfaces — by its unique coarse reticulations covering nearly the entire head (except the smooth medial frons) and mesosoma. The only congener sharing this reticulate sculpturing pattern, M. dasynota , differs markedly in multiple traits: (1) M. jiachengi Gu & Chen , sp. nov. possesses anterolateral clypeal projections and an arcuately concave anterior clypeal margin bearing a median denticle, contrasting with M. dasynota ’ s straight, denticle-free clypeal margin and absence of lateral projections; (2) the mesosoma of M. jiachengi Gu & Chen , sp. nov. features stout propodeal spines (basal width> length) directed posterodorsally with upturned apices, and a small propodeal spiracle (diameter 1 / 3 of distance to propodeal declivity), whereas M. dasynota with a slender, laterally directed spines (length> basal width), and a proportionally larger spiracle (diameter approximately 1 / 2 of distance to propodeal declivity); (3) the petiole of M. jiachengi Gu & Chen , sp. nov. much higher than long, with a steep anterior face, concave posterior face, and distinct subpetiolar process, while the petiole of M. dasynota is subequal in height and length, with gentle slopes and a reduced subpetiolar process; (4) the eyes of M. jiachengi Gu & Chen , sp. nov. larger (> 20 ommatidia), while eyes of M. dasynota smaller (≤ 15 ommatidia). The combination of these morphological and sculptural traits provides unequivocal diagnostic separation from all regional congeners.

Worker measurements.

(N = 5). HL 0.56–0.62, HW 0.56–0.61, CI 93–97, SL 0.45–0.47, SI 78–83, ED 0.06–0.07, MSL 0.68–0.72, PW 0.40–0.44, PL 0.16–0.18, PH 0.17–0.20, DPW 0.17–0.18, LPI 104–106, DPI 100–102, GL 0.84–0.91, TL 2.54–2.61.

Worker description.

Head. In full-face view, head subquadrate, lateral margins nearly parallel and posterior margin arcuately concave; posterolateral corners rounded. Mandibles with 8 teeth: apical two teeth robust, teeth 3–7 small but distinct, basal tooth larger than teeth 3–7 but distinctly smaller than apical tooth, with a denticle near inner margin. Clypeus with prominent anterolateral projections and arcuately concave anterior margin bearing a median denticle. Frontal lobes strongly laterally expanded. Antennae 12 - segmented, scapes reaching posterolateral corners. Eyes relatively large, composed of> 20 ommatidia. Mesosoma. In lateral view, propodeum stout, dorsum convex, eumetanotal spines inconspicuous. Propodeal spines robust, basal width greater than long, directed posterodorsally with apices slightly upturned. Propodeal spiracle small, its maximum diameter equal to 1 / 3 of its distance to propodeal declivity. In dorsal view, pronotum with prominent humeral corners; lateral margins nearly straight, converging posteriorly to propodeal spine bases. Propodeal spines stout, directed posterolaterally, length <1 / 3 of inter-spinal distance. Metasoma. In lateral view, petiole much higher than long, with triangular dorsal projection (anterior face steep, posterior face concave); subpetiolar process distinct, ventral margin shallowly concave. Gaster ovoid in shape. In dorsal view, both petiole and postpetiole wider than long; postpetiole with rounded anterodorsal corners and obtuse posterodorsal corners. Gaster with straight anterior margin and distinct anterolateral corners. Sculpture. Mandibles with two longitudinal grooves (inner wider than outer), otherwise smooth and shining. Clypeus smooth and shining. Scapes with dense longitudinal rugae. Head with coarse reticulations except smooth and shining medial area between frontal lobes. Lateroventral area of head with faint striae, generally smooth and shining. Mesosoma with coarse reticulations, pronotal sides with partial longitudinal striae ventrally. Petiole with longitudinal rugae; gaster smooth and shining. Pilosity and pubescence. Body with moderately dense erect hairs. Pubescence limited to antennal club. Coloration. Head black; mesosoma black dorsally, reddish-brown posterolaterally. Petiole and gaster reddish-brown to black, gaster predominantly black. Mandibles, antennae and legs yellowish-brown to reddish-brown.

Etymology.

The species epithet “ jiachengi ” is a Latinized noun in the genitive case, derived from the given name “ Jiacheng ” of the collector, Mr. Jiacheng Zhang. The name is proposed to honor Mr. Zhang’s invaluable contribution in collecting the type series of this new species, thereby recognizing his pivotal role in its discovery.

Distribution.

Shaanxi.

Figures

Figure 40. Myrmecina jiachengi Gu & Chen, sp. nov. A. Mesosoma in dorsal view; B. Head in full-face view; C. Body in dorsal view; D. Body in lateral view.