Bebryce otsuchiensis, Matsumoto, Asako K. & van Ofwegen, Leen P., 2016

Matsumoto, Asako K. & van Ofwegen, Leen P., 2016, The genus Bebryce (Cnidaria, Octocorallia, Plexauridae) at Japan, with descriptions of three new species, ZooKeys 587, pp. 1-20 : 4

Taxon classification Animalia Alcyonacea Plexauridae

Bebryce otsuchiensis sp. n. Figures 1, 2c, 3, 4, 5, 6

Material examined.

Holotype RMNH Coel. 42072 (AKM 703), Entrance of Otsuchi Bay, Iwate Prefecture, Japan, 39°21.8052'N, 142°00.0750'E - 39°22.0672'N, 141°59.9619'E, depth 67-81 m, RV Yayoi, st. 2, 1 m biological dredge, coll. A.K. Matsumoto, 23 May 2006; paratypes RMNH Coel. 42073 (AKM 531), Otsuki, Tosa, Kochi Prefecture, Japan, 32°34.14'N, 132°48.59'E - 32°34.18'N, 132°47.53'E, depth range 117-125 m, local fishermen’s boat Kiryo-maru, st. 2, coral net, coll. A.K. Matsumoto, 7 October 2004; RMNH Coel. 42074 (AKM 1628), Otsuki, Tosa, Kochi prefecture, Japan, 32°37.66'N, 132°50.44'E - 32°37.56'N, 132°47.88'E, depth 114 m, local fishermen’s boat Kiryo-maru, st. 1, coral net, coll. A.K. Matsumoto, 7 October 2004; RMNH Coel. 42075 (AKM 943), Toshima I., Izu Is., Japan, 34°33.1102'N, 139°17.4102'E - 34°33.6524'N, 139°17.6725'E, depth 143 m, RV Tansei-maru, KT07-31 cruise (Kuramochi leg), st. 22 (L-3-100), chain bag dredge, coll. A.K. Matsumoto, 27 November 2007.

Description.

The holotype RMNH Coel. 42072 consists of two branches, both 4 cm long. (Figure 2c). The calyces are placed spirally all around the slender branches, which are about 1 mm wide. The dome-shaped calyces are about 1 mm wide and high.

The anthocodiae are armed with a crown and points consisting of a transverse crown with curved, rather smooth spindles up to 0.40 mm long (Figure 3a) and eight points formed by spindles 0.35 mm long (Figure 3b) placed in a chevron-like pattern beneath the tentacles. These spindles have simple tubercles and a distal spiny end. The tentacles contain flattened, dragon wing sclerites up to 0.2 mm long (Figure 3c).

The sclerites of the outer surface of coenenchyme and calyces are rosettes consisting of a cup-shaped thorny projection arising from a warty base. Several of these are up to 0.10 mm long and have a widely flared calyx part of about 0.10 mm in greatest diameter with slightly serrated rim with a few blunt processes, joined by a smooth, slender stem to a warty base narrower than the calyx (Figure 3d); others do not flare out (Figure 4c). The rosettes become asymmetrical toward the calycular apertures (Figure 3e), with the calyx margin becoming elongated and forming a blade-like process that projects from the surface and surrounds the calycular aperture. These sclerites are up to 0.20 mm long.

The deeper layer of coenenchyme contains stellate plates, 3-6 rayed forms up to 0.15 mm in the greater diameter, with a central process (Figure 4a). Most are weakly tuberculated (Figure 4a) but several are more tuberculated towards the end of the rays (Figure 4b).

Colour. The holotype is light brown.

Etymology.

Named after the type locality, Otsuchi Bay.

Variation.

RMNH Coel. 42074 (AKM 1628) has slightly wider point sclerites, collaret spindles heavier tuberculate, and more tuberculate stellate plates (Figures 5-6).

Comparisons.

The species mostly resembles Bebryce harpy Grasshoff, 1999, regarding the blunt processes of the rosettes. It differs in overall having less tuberculate sclerites.

Remarks.

This is the northernmost species of Bebryce . It has a very wide distribution from North to South Japan, and is only found in the warm Kuroshio Current area, in the depth range 67-143 m. This species also represents the northernmost record of the genus Bebryce , and the first from north of 39°N latitude.