Nylanderia emmae ( Forel, 1894 )

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 : 516-517

Nylanderia emmae ( Forel, 1894)

( Figure 14 ; Figure 25.C )

Prenolepis emmae Forel, 1894 c: 406 (footnote). China ( Hong Kong).

In Prenolepis (Nylanderia) : Emery, 1906: 133; in Paratrechina (Euprenolepis) : Emery, 1925: 224; in Prenolepis: Brown, 1953 h: 7 (where the name was wrongly rendered as Prenolepis geei ; see Wheeler, 1930: 80 for correspondence of data); in Nylanderia: Williams & LaPolla, 2016: 245 .

Diagnosis. Nylanderia emmae can be distinguished from other species of Nylanderia from Southeast China by the combination of oval-shaped head, yellow to light brown coloration, yellow to light brown macrosetae, malar area with longitudinal rugulae, mesopleuron without pubescence, promesonotal suture and metanotal groove complete, and mesopleuron and lateral area of propodeum with longitudinal striation.

Measurements (n = 3 workers). ClL 0.195 –0.268; ClW 0.48–0.556; HL 0.808 –0.855; HW 0.743 –0.773; EL 0.193 –0.211; MaD 0.160 –0.170; IoD 0.424 –0.447; SL 1.020 –1.208; ML 1.259 –1.379; PrL 0.463 –0.482; PrW 0.510 –0.521; PrFL 0.376 –0.414; MeL 0.218 –0.279; MeW 0.237 –0.242; PrpL 0.274 –0.301; PrpH 0.390 –0.436; PrpW 0.376 –0.414; PL 0.285 –0.335; Ab3L 0.588 –0.615; TL 2.99–3.15; PMC 4–5; MMC 3–4; CI 88.4–91.9; DNI 45.4–46.4; IoI 57.0–59.0; OI 25.9–27.3; SI 137.3–156.3; REL 22.9–24.7; MaI 75.8–88.1.

Compare with: N. birmana , N. flaviabdominis , N. IBBL-01, N. yaeyamensis .

Morphology. Along with N. flaviabdominis , this species has a very peculiar set of characters that make them easily recognizable among the Nylanderia species in the region (see Diagnosis for both N. emmae and N. flaviabdominis ). Given their long and ‘constricted’ mesosoma, both species were thought to belong to Prenolepis when first described. However, both morphological and molecular evidence supports their placement in Nylanderia ( Blaimer et al. 2015; Williams & LaPolla 2016).

In the seven specimens analyzed in this work, there was little variation in all characters. Most variations observed were related to the type of sculpture, especially in the malar region; nonetheless, the degree of variation was minimal. Additionally, we observed color variation among specimens, some of them being considerably darker, with an overlap in coloration with N. flaviabdominis (which is mostly dark orange-brown; see Williams & LaPolla 2016). This color variation could influence equivocal species identification (e.g. Liu et al. 2015), despite malar and propodeal sculpture differing consistently between N. emmae and N. flaviabdominis . Misidentification of both species could possibly be influenced by the lack of inclusive and recent revisionary works for the genus in the region. Although we had the opportunity to study several specimens, N. emmae still has a low representation in samples, being infrequently collected, even at local scales, affecting our comprehension of character variation in this species.

Ecology. Specimens studied here were mostly sampled in better preserved areas (i.e., country parks) at different elevations. Most commonly, individuals of N. emmae were found in locations above 230 m a.s.l., with some specimens being found below that (e.g., in samples from Tai Po Kau at 77 m a.s.l.).

Distribution. Nylanderia emmae appears to be widely distributed in China, although being locally uncommon.

Examined material. Hong Kong: (2 workers) Lung Fu Shan , 22.279 114.1361, elevation 250 m, 8.vii.2020, P. Schultheiss col.; (1 worker) Tai Po , Tai Po Kau , 22.39566 114.14997 ±500 m, elevation 245 m, 25.v.2016, Y. Luo col., #ISP0077; (1 worker) Tai Po , Tai Po Kau , 22.43245 114.18593 ±500 m, elevation 77 m, 17.v.2016, Y. Luo col., #ISP0054; (1 worker) Southern , Tai Tam, 22.26700 114.21329 ±500 m, elevation 341 m, 16.ix.2016, C. Leung col., #Ba-IAS-22-02-21; (1 worker) Tai Mo Shan, 22.42354204 114.128245, elevation 592 m, 14.ix.2022, M. Hamer & A. Ibañez col., TMS2T3W4-1; (1 worker) same data as preceding, 22.42358102 114.128304, elevation 590 m, 14.ix.2022, M. Hamer & A. Ibañez, TMS2T4W3-3 [ IBBL]; (1 worker), Victoria Park, 27.vi.1999, Sk. Yamane [ SKYC] .

Figures

FIGURE 14. Nylanderia emmae. A: Lateral view of the whole body; B: Dorsal view of the head; C: Dorsal view of the whole body.

FIGURE 25. Distribution maps for seven of the thirteen Nylanderia species recorded for Hong Kong. A: Nylanderia amia; B: Nylanderia birmana; C: Nylanderia emmae; D: Nylanderia flaviabdominis; E: Nylanderia flavipes; F: Nylanderia IBBL-01; G: Nylanderia IBBL-02.