Gauromyrmex orbihumerus Chen & Chen, 2022

Chen, Defu & Chen, Zhilin, 2022, Ants of the genus Gauromyrmex Menozzi (Hymenoptera: Formicidae), with description of a new species from China, Asian Myrmecology (e 015007) 15, pp. 1-10 : 8-9

Gauromyrmex orbihumerus Chen & Chen sp. nov.

http://zoobank.org/ 916FE637-819C-4987-8E5D- 2CD1CF4E962D

( Figs. 14-16 )

Material examined. Holotype worker, CHINA: Guangxi, Daxin, Xialei Protection Zone , 22.58°N, 106.75°E, 24.VII.2018, leg. Zhilin Chen, No. G 187739 ; Paratypes: 2 workers from the same colony as the holotype work- er. Type workers deposited in GXNU (Insect Collection, Guangxi Normal University , Guilin , Guangxi, China ) .

Diagnosis. Anteromedian margin of clypeus concave. In lateral view, dorsum of pronotum convex; dorsum of mesonotum almost straight, and leaning forward slightly; dorsum of propodeum convex and declining posteriorly, about 1.5 times as long as its declivity, forming a tooth between dorsal margin and declivity, declivity concave. In dorsal view, humeral corners of pronotum rounded. Subpetiolar process triangular translucently; anterior 5/6 part of head with longitudinal stria; dorsum of promesonotum shiny, with fine stria; lateral face of mesosoma rugose longitudinally, dorsum of propodeum punctate-reticulate.

Description. Holotype worker. TL 2.88, HL 0.64, HW 0.61, CI 95, SL 0.36, SI 59, ED 0.13, PW 0.39, MSL 0.77, PL 0.21, PH 0.18, DPW 0.13, LPI 86, DPI 62.

Head. In full-face view head rectangular, slightly longer than broad, narrowed posteriorly, posterior margin in middle weakly concave, posterolateral corner rounded, lateral margin even. Mandibles triangular, masticatory margin with 6 teeth, with large apical tooth and preapical tooth, followed by 4 same size denticles; anteromedian margin of clypeus concave. Frontal carina and antennal scrobes absent. Antenna 12-segmented, scape not surpassing posterior margin of head. Eyes median size, 8 ommatidia in longest row, located midpoint of lateral margin. Mesosoma. In lateral view, dorsum of pronotum convex; dorsum of mesonotum almost straight, and leaning forward slightly; dorsum of propodeum convex and declining posteriorly, about 1.5 times as long as its declivity, forming a tooth between dorsal margin and declivity, declivity concave. In dorsal view, humeral corners of pronotum rounded; lateral sides of pronotum concave; posterodorsal corner of pronotum with a pair of blunt process, and not passing smoothly to lateral margins of mesonotum; promesonotal suture absent; metanotal groove depressed, and strongly constriction between mesonotum and propodeum; lateral margin of propodeum convex, posterolateral corner forming a pair of spines. Waist. Petiole in lateral view peduncle short, anterodorsal corner forming an obtuse denticle, dorsum with a strong tooth, subpetiolar process triangular translucently; in dorsal view, petiole rectangular, anterolateral corner obtuse denticle, anterior margin concave, with a transverse ridge in middle. Postpetiole in lateral view smaller than petiole, anterior margin convex, dorsum narrowed, posterior margin steep, sternite of postpetiole much smaller than its stergite, anteroventral obtuse; in dorsal view anterolateral corner of postpetiole rounded, lateral margin convex and narrowed posteriorly. Gaster. Gaster in lateral view oval, in dorsal view humeral corner of gaster obtuse-angulate. Sculpture. Mandibles scattered with piligerous punctures and weakly stria; middle part of clypeus smooth and shiny, and its lateral part with several stria; outer face of antennal sockets with dense concentric stria,anterior 5/6 part of head with longitudinal stria, and rest of head so shiny. Dorsum of promesonotum shiny, with fine stria; face of metanotal groove scattered with several ridges; lateral face of mesosoma rugose longitudinally, dorsum of propodeum punctate-reticulate. Lateral face of petiolar node and postpetiole reticulate finely; dorsum of petiole and postpetiole smooth and shiny, sometime with sparse ridges. Gaster smooth and shiny. Pilosity. Head with abundant erect hairs and sparse pubescences, mesosoma, petiole, postpetiole and gaster sparse with erect hairs pubescence. Color. Body yellow to yellowish-brown.

Paratype workers. TL 2.82–2.92, HL 0.64–0.69, HW 0.60–0.63, CI 94–95, SL 0.35–0.37, SI 59–60, ED 0.13, PW 0.38–0.39, MSL 0.76– 0.79, PL 0.20–0.22, PH 0.19–20, DPW 0.12– 0.13, LPI 85–87, DPI 62–63 (n = 2) .

Remarks. The new species is extremely similar to G. acanthinus , but can be distinguished from the latter by the following characters of workers: humeral corners of pronotum rounded in dorsal view; anterior 5/6 part of head with longitudinal stria, and rest of head shiny, dorsum of promesonotum fine stria; lateral face of mesosoma rugose longitudinally; dorsum of propodeum punctate-reticulate. In addition, the difference between this species and G. bengkalisi is shown in couplet 2 of the key.

Habitat. This species was collected from the trunk of Elaeocarpus decipiens Hemsl. , about 1.5 meters above the ground.

Etymology. The name “ orbihumerus ” refers to the rounded humeral corners of pronotum.

Figures

Figs. 14 – 16. Gauromyrmex orbihumerus sp. nov. Holotype worker. 14. Head in full-face view; 15. Body in dorsal view; 16. Body in profile view.A. Head in full-face view; B. Mandible in full-face view; C. Body in dorsal view; D. Body in profile view.