Nylanderia yaeyamensis (Terayama, 1999)

Guénard, Benoit, 2023, A checklist of Nylanderia (Hymenoptera: Formicidae: Formicinae) from Hong Kong and Macao SARs, with an illustrated identification key for species in Southeast China and Taiwan, Zootaxa 5301 (5), pp. 501-539 : 531-532

Nylanderia yaeyamensis

( Figure 23 ; Figure 26.E )

Diagnosis. Nylanderia yaeyamensis can be distinguished from other species of Nylanderia from Southeast China by the combination of dorsum of head and mesonotum without abundant pubescence, eye longer or as long as malar distance (MaI 80.3–88.2), eye length 3x times the lateral margin of head (REL 18.9–23.9), dorsum of propodeum convex, head and mesosoma yellow to light brown, and third to fifth gastral segments dark brown.

Measurements (n= 3 workers). ClL 0.155 –0.162; ClW 0.424 –0.472; HL 0.659 –0.672; HW 0.543 –0.596; EL 0.127 –0.157; MaD 0.11–0.129; IoD 0.344 –0.395; SL 0.715–0.78; ML 0.826 –0.857; PrL 0.263 –0.271; PrW 0.409–0.44; PrFL 0.585 –0.625; MeL 0.182 –0.247; MeW 0.199 –0.222; PrpL 0.151 –0.185; PrpH 0.291 –0.307; PrpW 0.289 –0.305; PL 0.257 –0.267; Ab3L 0.367 –0.463; TL 2.2–2.3; PMC 2–3; MMC 2–3; CI 82.4–88.7; DNI 47.5–54.3; IoI 63.4–66.7; OI 21.4–29; SI 130.9–132.9; REL 18.9–23.9; MaI 80.3–88.2.

Compare with: N. emmae , N. flaviabdominis , N. IBBL-01, N. picta .

Morphology. Nylanderia yaeyamensis is similar to N. IBBL-01 and N. picta , although it can be easily separated from N. IBBL-01 by the presence of a median concavity in the posterior margin of the head and from N. picta by the size of eyes (larger in N. yaeyamensis ) and overall size of the body. The coloration of the gastral sclerites varied to some extent, sometimes overlapping with the coloration found in some specimens of N. IBBL-01. Two workers sampled in Hong Kong (#ISP0083 and #ISP0061) had different PMC and MMC values when compared to Terayama’s (1999) description and to other specimens studied here, with both having PMC 3 and MMC 3.

Ecology. Specimens were sampled in areas with different degrees of anthropogenic influence and at different elevations, suggesting a possible absence of habitat preference.

Distribution. Nylanderia yaeyamensis is not abundant in Hong Kong and Macao, but appears to have a relatively wide distribution range, including Guangxi, Japan (Yaeyama Islands), and Taiwan ( Guénard et al. 2017; Janicki et al. 2016). The distribution gaps in between (e.g., its absence in Guangdong) could be due to the absence of identification keys or by the lack of more inclusive taxonomic studies for the genus in the region.

Examined material. Hong Kong: (1 worker) Tai Po , Tai Po Kau, 22.43245 114.18593 ±500 m, elevation 77 m, 25.v.2016, Y. Luo col. #ISP0083; (1 worker) Tsuen Wan, Shing Mun, 22.39494 114.15486 ±500 m, elevation 195 m, 18.v.2016, Y. Luo col. #ISP0061; (1 worker) same data as preceding, elevation 197 m, 16.v..2016, Y.Luo col. #ISP0042; (1 worker) same data as preceding, 22.38969 114.15310 ±500 m, elevation 201 m, 18.v.2016, Y. Luo col. #ISP0071 .; Macao: (3 workers) Alto de Coloane , 22º7’35.71”N 113º34’21.78”E, 19.iii.2019, F. Brassard col.

Figures

FIGURE 23. Nylanderia yaeyamensis. A: Lateral view of the whole body; B: Dorsal view of the head; C: Dorsal view of the whole body.

FIGURE 26. Distribution maps for seven of the thirteen Nylanderia species recorded for Hong Kong.A: Nylanderia indica; B: Nylanderia picta; C: Nylanderia sharpii; D: Nylanderia taylori; E: Nylanderia yaeyamensis; F: Nylanderia yerburyi.