Ischnochiton boninensis Bergenhayn, 1933

Sirenko, Boris I. & Zhang, Junlong, 2019, Chitons (Mollusca: Polyplacophora) of Hainan Island and vicinity, South China Sea, Zootaxa 4564 (1), pp. 1-40 : 6

Ischnochiton boninensis Bergenhayn, 1933

( Fig. 2B )

Ischnochiton boninensis Bergenhayn 1933: 10 , fig. 3, pl. 1: figs 2–3, pl. 2: figs 24–29, 32; Is. Taki 1938: 369; Leloup 1941: 12; Azuma 1960: 1; Kira 1964: 183, pl. 67: fig. 2; Habe 1971: 68, fig. 5; Higo 1973: 6; Cardin 1976: 90; Kaas & Van Belle 1980: 18; 1998: 33; Van Belle 1982: 470; Bullock & Harper 1994: 19, pls. 1E–F, 3E–F, 4C, 5C–F; Saito 1995: 105; 1998: 151; 2000: 13, pl. 6, fig. 15; 2001: 196, fig. 3; 2006: 212; 2017: 48, 732, pl. 4, fig. 11; Xu 2008: 457; Owada 2016: 259, figs 4A–E, 5A–D; Owada 2018: 284, Table 3.

Ischnochiton (Ischnochiton) comptus ( Gould, 1859) forma isaoi Iw. Taki, 1964a: 348, figs 2, 4, 6; 1964b: 408.

Ischnochiton (Simplischnochiton) lepidus ; Van Belle 1980: 33 (non Gould, 1859).

Ischnochiton (Simplichnochiton) boninensis ; Dell’Angelo et al. 1990: 36.

Ischnochiton (Ischnochiton) boninensis ; Is. Taki 1962: 43; Kaas & Van Belle 1990: 184, fig. 83. map 39 (bibliography and synonymy).

Type material. UUZM .

Type locality. Japan, Bonin Islands .

Material examined. South China Sea, Hainan Island, stn. 2, 20°09’36’’N, 110°41′17’’E, SCUBA, depth 1–3 m, on stones, 11 spms, BL – 5.0–11.0 mm, 13.11.2016, leg. B. Sirenko, S. Grebelniy; stn. 27, 18°18′03’’N, 109°13′55’’E, depth 2–5 m, on stones covered with red crustose algae, 1 spm, BL – 15.0 mm, 24.11.2016, leg. B. Sirenko; stn. 27, 18°18′03’’N, 109°13′55’’E, depth 1.5– 2 m, on stones, 21 spms, BL – 6.0–12.0 mm, 24.11.2016, leg. B. Sirenko.

Distribution. South China Sea, north Vietnam from 18°06’05’’N, 106°27′55’’E to Cat Ba Island (20°47’23’’N, 107°06’13’’E), China, Hainan Island, Hong Kong, Yellow Sea, Qingdao, near south Korea and south Japan, from intertidal to depth 2– 5 m.

Remarks. Ischnochiton boninensis often inhabits the same regions as I. comptus along the coast of North Vietnam and south China. They are very similar but easy to differentiate by their dorsal scales. The scales of I. boninensis have ribs while the scales of I. comptus are smooth and glossy. In order to see ribs under a light microscope it is necessary to dry the girdle slightly with paper.

Figures

FIGURE 2. Complete specimens of species of genera Callochiton, Ischnochiton, Lepidozona and Rhyssoplax: A. Callochiton multidentatus, Hainan, stn 27, BL 5.5 mm; B. Ischnochiton boninensis, Fujian Province, BL 17.0 mm; C. Ischnochiton comptus, Hainan, stn 29, BL 12.0 mm; D. Lepidozona coreanica, Hainan, stn 2, BL 22.0 mm; E. Rhyssoplax komaiana, Hainan, 57-1051, BL 12.0 mm; F. Rhyssoplax venusta, Guangxi Province, BL 11.5 mm.