Ponera swezeyi Wheeler, 1933

Leong, Chi-Man, Guénard, Benoit, Shiao, Shiuh-Feng & Lin, Chung-Chi, 2019, Taxonomic revision of the genus Ponera Latreille, 1804 (Hymenoptera: Formicidae) of Taiwan and Japan, with a key to East Asian species, Zootaxa 4594 (1), pp. 1-86 : 52-54

Ponera swezeyi Wheeler, 1933

( Fig. 50 : worker)

Pseudocryptopone swezeyi Wheeler, 1933: 16 (w. q.). Type locality: Hawaii .

Ponera swezeyi: Wilson, 1957: 370 ; Taylor, 1967: 85; Terayama, 1996: 14.

Non-type material examined: JAPAN . 2 workers, Okiminato, Hahajima, Ogasawara Is., 19 III 1977, M Shindo leg (MTC: LCM_MT-Ponera-05).

Measurements (mm) and indices. Worker (n=1): HL 0.41; HW 0.34; SL 0.26; A06L 0.02; A07L 0.02; A08L 0.03; A09L 0.04; A10L 0.05; PrW 0.25; WL 0.51; PeH 0.26; PeNL 0.14; PeW 0.19; ATL 0.28; ATW 0.32; CI 82, SI 76, PeI 77, LPeI 53, DPeI 142, ATI 90.

Diagnosis (worker). Ponera swezeyi can be easily distinguished by a short antennal scape and the presence of a five segmented club, a metanotal groove distinct, a petiolar node in lateral view thick and trapezoidal with straight anterior and posterior margins, its small body size (HW: 0.32–0.34 mm), and the yellowish brown body color.

Description of worker. See Wheeler (1933).

Description of queen. See Wheeler (1933).

Description of male. Unknown.

Distribution. Australian: Tanzania, Sino-Japanese: Ogasawara Islands; Oriental: Christmas Island; Oceanai: Fiji, Hawaii, Solomon Islands; Madagascan: Madagascar.

Remarks. Ponera swezeyi belongs to the P. japonica species group defined by Taylor (1967), which includes P. japonica , P. incerta and P. swezeyi . These three species have a five segmented antennal club, yellow to brown body color and are widely distributed within the Sino-Japanese, Oriental and Oceanian regions. Recently, three Oriental species, P. baka Xu, 2001 and P. xatha Xu, 2001 from Yunnan; P. shennong Terayama, 2009 from Taiwan were discovered, and show important similarities with P. swezeyi (yellowish brown body color, five segmented antennal club, small body size and thick petiolar node). Here, our morphological comparison suggests that P. swezeyi is similar to P. baka , P. shennong and P. xatha , instead of P. japonica and P. incerta for the following reasons:

(1) Head width in P. baka (HW: 0.33 mm), P. xatha (HW: 0.35 mm), P. shennong (HW: 0.28 mm) and P. swezeyi (HW: 0.32–0.33 mm) is distinctly smaller than P. incerta (HW: 0.36–0.40 mm) and P. japonica (HW: 0.41–0.50 mm) (see the references in Table 1 );

(2) Petiolar node in lateral view very thick in P. baka , P. shennong , P. swezeyi and P. xatha , but moderately thick in P. incerta and P. japonica ;

(3) Antennal scape short in P. baka , P. shennong , P. swezeyi and P. xatha (when laid backward, with a remaining distance of more than 30% of the scape length to the posterolateral corner), but relatively long in P. incerta and P. japonica (when laid backward, with a remaining distance of less than 15% of the scape length to the posterolateral corner);

(4) Body color yellowish in P. baka , P. shennong , P. swezeyi and P. xatha , but brown in P. incerta and P. japonica .

These morphological similarities suggest that P. swezeyi might be closer to the Oriental species than to P. japonica and P. incerta . Although the reported distribution of P. swezeyi is wide (antmaps.org 2017), this species may be native to the Oriental region.

Figures

FIGURE 50. P. swezeyi worker (LCM_MT-Ponera-05a), A: body, lateral view, B: body, dorsal view, C: head, full-face view.