Melithaea tanseii, Matsumoto, Asako K. & van Ofwegen, Leen P., 2015

Matsumoto, Asako K. & van Ofwegen, Leen P., 2015, Melithaeidae of Japan (Octocorallia, Alcyonacea) re-examined with descriptions of 11 new species, ZooKeys 522, pp. 1-127 : 33-34

Taxon classification Animalia Alcyonacea Melithaeidae

Melithaea tanseii sp. n. Figures 87a, 88, 89, 98

Material examined.

Holotype RMNH Coel. 41937 (AKM 948), Toshima Is., Izu Isls., 34°33.1102'N, 139°17.4102'E - 34°33.6524'N, 143 m, R/V Tansei-maru, KT07-31 (Kuramochi leg.) St. 22 (L-3-100), coll. A.K. Matsumoto; paratype: RMNH Coel. 41938 (AKM 941) Toshima Is., Izu Isl, 34°34.4640'N, 139°18.3760'E - 34°33.5601'N, 139°17.8631'E, 152-198 m, R/V Tansei-maru, KT07-31 (Kuramochi leg.) St. 21 (L-3-200), coll. A.K. Matsumoto.

Description.

The holotype (RMNH Coel. 41937) consists of a large number of branches probably belonging to one colony broken up while collecting (Fig. 87a). The largest fragment, with the holdfast, is 6.5 cm long. The stem is 10 mm long and 3 mm wide; branching is in one plane. A few anastomoses are present. The polyps are situated on one side of the colony. The calyces are dome-shaped, about 0.5 mm high and 1 mm wide. Many polyps are expanded. Points with slightly bent spindles up to 0.20 mm long, distal end with more developed tubercles (Fig. 88a). Collaret with bent spindles up to 0.25 mm long, middle part with more developed tubercles (Fig. 88b). Tentacles with platelets, the larger ones crescent-shaped (Fig. 88c). These platelets are up to 0.15 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 88d). Coenenchyme with capstans (Fig. 89a) 0.05-0.07 mm long, several slightly unilaterally foliate (Fig. 89b), unilaterally foliate spindles (Fig. 89c), small clubs of the same length as the capstans (Fig. 88e); spindles 0.10-0.25 mm long (Fig. 89d); all with simple tubercles. The calyces with additional clubs, up to 0.20 mm long (Fig. 88f).

Color.

Colony white with the larger yellowish nodes shining through the coenenchyme. All sclerites colorless.

Distribution.

Izu Isls (Fig. 98).

Etymology. The species is named after the R/V Tansei-maru.

Remarks.

The paratype (RMNH Coel. 41938) is just a fragment of colony, only three cm long with characters alike those of the holotype. The species mostly resembles Melithaea tenuis but differs in having much wider coenenchymal spindles, up to 0.07 mm wide, twice as wide as in Melithaea tenuis , in which they are only 0.03 mm wide. A few spindles in Melithaea tenuis are wider, mainly caused by the spindles having bigger tubercles. Another difference is the slightly bigger capstans in the new species, but this is only noticeable when having both species.