BASEODISCUS ZEBRA SP. NOV.

(FIG. 2P)

Baseodiscus mexicanus: Colin & Arneson, 1995: 150– 151, fig. 686 (Palau); Chernyshev & Volvenko, 2008: 106 (Komodo, Indonesia); Kajihara, Yoshida & Uyeno, 2012: 754–755, fig. 2A, B (Okinawa, Japan); Kajihara, 2017: 423, fig. 16.2d.

Zoobank registration: u r n: l s i d: z o o b a n k. org:act: EAA8D387-3EC0-4F9B-AE38-2DED799D7DFB.

Material examined: Holotype, RUMF-ZN-00001 (DNA voucher ICHUM 6317), 31 March 2012, 3–4 m depth, Cape Manza (26°30′16″N, 127°50′39″E), On’na-son, west coast of Okinawa-jima, Japan, SCUBA, collected by D. Uyeno.

Sequences: From ICHUM 6317: LC178607, 18S (1795 bp); LC178639, 28S (2086 bp); LC178688, 16S (505 bp); LC190960, COI (658 bp) .

Etymology: The new specific name is a noun in the nominative case, referring to the colour pattern of the species.

Description: Head white, with indigo dorsal and ventral cephalic patches; with transverse cephalic furrow encircling neck; numerous secondary furrows present; numerous, small, black eyes distributed laterally along sides of head. Body white, with numerous bands of same colour as cephalic patches (Fig. 2P).

Distribution: Although molecularly confirmed only from the type locality, Okinawa (Japan), B. zebra is probably distributed widely in the western Pacific.

Remarks: Sequences LC190960 (COI) and LC178688 (16S) from the holotype differ by 12.6% and 6.8% in uncorrected p -distance from KF935503 (COI) and KF935449 (16S), respectively, both from MCZ IZ- 135321 collected in Baja California, Mexico and identified as B. mexicanus by G. Giribet (Kvist et al., 2014; MCZbase, www.mcz.harvard.edu). Kajihara et al. (2012) argued a possible amphi-Pacific distribution for B. mexicanus, but the western-Pacific population (possibly extending from Japan via Palau to Australia; Colin & Arneson, 1995; Chernyshev & Volvenko, 2008) is here regarded as a distinct species.

Because the type locality of B. mexicanus is Mazatlán, Mexico (Bürger, 1893), the name mexicanus should be applied to the eastern-Pacific population, in which Coe (1940: 261) noted the colour to be variably brownish green, maroon, deep red, mahogany or brownish violet. The body colour appears to be generally reddish in B. mexicanus, whereas in B. zebra it is bluish.