Nylanderia sharpii ( Forel, 1899 )

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 : 528-529

Nylanderia sharpii ( Forel, 1899)

( Figure 21 ; Figure 26.C )

Prenolepis sharpii Forel, 1899 a: 121 , fig. 1. Hawaii.

In Paratrechina (Nylanderia) : 1925: 221; in Nylanderia: LaPolla et al., 2010: 127 .

Diagnosis. Nylanderia sharpii can be distinguished from other species of Nylanderia from Southeast China by the combination of mesonotum with sparse pubescence, dorsum of head with abundant pubescence, eyes relatively large (REL 28.3–29.7) with 10 to 12 ommatidia in the longest row, posterior margin of head, in dorsal view, medially concave, pronotum with 10 to 14 erect macrosetae (PMC 5–7), mesonotum with 6 to 8 erect macrosetae (MMC 3–4), and dark macrosetae on the whole body.

Measurements (n = 3 workers). ClL 0.151 –0.152; ClW 0.384 –0.399; HL 0.595 –0.645; HW 0.52–0.574; EL 0.168 –0.191; MaD 0.086 –0.094; IoD 0.317–0.34; SL 0.651–0.75; ML 0.758–0.83; PrL 0.273–0.28; PrW 0.391 – 0.425; PrFL 0.536 –0.605; MeL 0.184 –0.221; MeW 0.229 –0.249; PrpL 0.152 –0.179; PrpH 0.294 –0.305; PrpW 0.293 –0.305; PL 0.226 –0.266; Ab3L 0.382 –0.463; TL 2–2.3; PMC 5–7; MMC 3–4; CI 87.4–89; DNI 58.6–58.6; IoI 59.3–61; OI 32.4–33.3; SI 125.2–130.7; REL 28.3–29.7; MaI 49.3–51.2.

Compare with: N. amia , N. flavipes , N. IBBL-01, N. ryukyuensis , N. taylori , N. vividula .

Morphology. Like N. flavipes , specimens belonging to N. sharpii have relatively large eyes (MaI 49.3–51.2; REL 28.3–29.7), with 10 to 12 ommatidia in the longest row, sparse pubescence in the mesonotum, and abundant pubescence in the dorsum of the head.Also, N. flavipes have an erect macrosetae count of PMC 5 and MMC 3, while N. sharpii have an erect macrosetae count of PMC 5–7 and MMC 3–4. The most significant difference between these species is the color of the macrosetae, which is lighter in the former and darker in the latter. Based solely on workers, it is very difficult to differentiate N. flavipes and N. sharpii , especially considering the variation in erect macrosetae count in N. sharpii . However, according to Forel’s descriptions of the male genitalia of N. flavipes (Forel 1900) and N. sharpii ( Forel 1899) , they differ substantially. However, since we did not study males in the present work, it was not possible to explore this set of characters.

Ecology. In this study, specimens belonging to this species were mostly found in disturbed areas (e.g., Chek Lap Kok, Disneyland, and Tsuen Wan Riviera Park). Interestingly, specimens were found in both ground and arboreal baits (in the Macao samples), in elevations varying from 2 m a.s.l. to 105 m a.s.l.

Distribution. Nylanderia sharpii appears to be uncommon in Hong Kong and Macao, although having a wide known distribution in China.

Examined material. Image of a syntype worker from Hawaii , USA (CASENT0903123) deposited in NHMUK, London , United Kingdom. Hong Kong: (1 worker) Yuen Long: Mai Po, 22.48794 114.04089 ±500 m; elevation 6 m, 13.vii.2016, M. Pierce col. , # Ba-IAS-15-01-08; (1 worker) Yuen Long : Lok Ma Chau, 22.51384 114.06326 ±10 m, elevation 6 m, 07.x.2016, M. Pierce col. , # IAS-0134; (1 worker) Islands : Disneyland, 22.31825 114.04195 ±10 m, elevation 25 m, 28.ix.2016, M. Pierce, #IAS-0089; (1 worker) Tsuen Wan Riviera Park , 22.36359 114.11260, elevation 12 m, 09.viii.2021, Winkler, M.T. Hamer col. , TWR1T1W1-1; (1 worker) Tuen Mun : Pillar Point Sewage Station, 22.36561 113.94457, elevation 2 m, 25-02.vi-vii.2021, Malaise, A. Ibañez col. , PP2M1-2; Macao: (2 workers) Coloane Island , Coloane Trail , 22.11507N 113.56448E, elevation 83 m, 29.viii.2019, arboreal bait, F. Brassard col.; (2 workers) Coloane Island , Cotai Ecological Zone II, 22.1418N 113.5519E, elevation 2 m, 9.x.2019, arboreal bait, F. Brassard col.; (4 workers) Coloane Island , Coloane Trail , 22.1217N 113.556E, elevation 105 m, 11.vii.2019, ground bait, F. Brassard col.

Figures

FIGURE 21. Nylanderia sharpii. 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.