Xenia bauiana May, 1899

Halász, Anna, Mcfadden, Catherine S., Toonen, Robert & Benayahu, Yehuda, 2019, Re-description of type material of Xenia Lamarck, 1816 (Octocorallia: Xeniidae), Zootaxa 4652 (2), pp. 201-239 : 206-207

Xenia bauiana May, 1899

Fig. 2

Xenia bauiana May, 1899: 88

Xenia bauiana ; Kükenthal 1902: 655–656

Material. Syntype: ZMB 3673 , Zanzibar, 1885, coll. Sander.

Description. The syntype is 25 mm high; its stalk is 14–20 mm long and 12 mm wide at its base and 28 mm wide at the uppermost part. The polyp body is up to 9 mm long, and the tentacles are up to 4 mm long, featuring four rows of pinnules on each side. The pinnules are relatively short and slender, up to 0.50 mm long and 0.15 mm wide, 26–30 in the outermost row with no gap between adjacent pinnules.

Sclerites are ellipsoid platelets, occasionally slightly irregular 0.008 –0.014 X 0.015 –0.020 mm in diameter ( Fig. 2a, n =25). They are composed of calcite rods ( Fig. 2b ) thus providing a granular appearance to the sclerite surface, which is mostly fractured ( Fig. 1a ). The ethanol-preserved holotype is brown-gray in color.

Remarks. In the original description of X. bauiana, May (1899) indicated three rows of pinnules, but not their number on the margins of the tentacles. Later, Kükenthal (1902) noted that this species features six rows, probably referring to the total number – namely, three on each side of the tentacle. Both of these descriptions lack details regarding the number of pinnules and sclerite dimensions. The current findings further indicate that the number of rows of pinnules recorded in previous studies is erroneous ( May 1899: 3 rows; Kükenthal 1902: 6 rows; and this study: 4 rows).

Similar species and conclusion. Both X. bauiana and X. sansibariana feature four rows of pinnules with 26– 30 and 25–27 pinnules in the outermost row, respectively, and share the same type locality. Notably, X. sansibariana lacks sclerites and thus these two species should be considered as separate.

Distribution. Zanzibar.

Figures

FIGURE 1. Scanning electron micrographs of polyp sclerites of Xenia flexibilis n. sp. holotype (ZMB 6105). a. Ellipsoid platelets, some fractured; b. Fractured sclerite revealing matrix of calcite rods, more or less radially arranged, at peripheral region; c. Overview of group of sclerites. Scale bar 0.010 mm.

FIGURE 2. Scanning electron micrographs of polyp sclerites of Xenia bauiana May, 1899 syntype (ZMB 3673). a. Ellipsoid platelets, mostly fractured; b. Fractured sclerite composed of dendritic rods, more or less radially arranged in the peripheral region; Scale bar at a 0.010 mm, at b 0.005 mm.