Xenia grasshoffi Verseveldt, 1974

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 : 214

Xenia grasshoffi Verseveldt, 1974

Fig. 8

Xenia grasshoffi ; Verseveldt, 1974a: 34–35, Fig. 34

Material. Holotype: SMF 2616 , northern Red Sea, Gulf of Aqaba, Eilat, 1968, coll. M. Grasshoff.

Description. The holotype is 28 mm high; its stalk is 23 mm long, 10 mm wide at its base and 25 mm wide at the uppermost part. The polyp body is up to 3 mm long, and the tentacles are up to 2 mm long, featuring four rows of pinnules on each side. The pinnules are relatively short and stout, up to 0.24 mm long and 0.20 mm wide, 15–24 in the outermost row with no gap between adjacent pinnules.

Sclerites are ellipsoid platelets, measuring 0.009 –0.017 X 0.015 –0.023 mm in diameter ( Fig. 8 a–d, n=27). Occasionally, a crest is present on the surface of the sclerite ( Fig. 8b, d ). Rarely, a median waist can be seen ( Fig. 8a ). They are composed of calcite rods arranged radially, and at the center of the sclerite they are randomly arranged ( Fig. 8b, c ). Many of the sclerites are fractured ( Fig. 8a, b, d ). The ethanol-preserved holotype is light cream in color and polyps are almost white.

Remarks. The current findings correspond to the original description of X. grasshoffi ( Verseveldt 1974a: four rows and 15–24 pinnules vs. four and occasionally five rows and 16–20 pinnules, respectively). The sclerites were originally described as: "spicules of general xeniid type: round or oval corpuscle" and the current measurements reveal that their size corresponds to the original description (0.009 –0.017 X 0.015 –0.023 vs. 0.024 in the stalk and 0.021 in the tentacles, respectively).

Similar species. Xenia flexibilis n. sp. and X. grasshoffi feature four rows of pinnules and a certain overlap in the number of pinnules in the outermost row (14–32 vs. 15–24). However, the sclerites of X. grasshoffi feature surface crests which are absent in X. flexibilis and thus they should be considered as separate species.

Distribution. Red Sea.

Figures

FIGURE 8. Scanning electron micrographs of polyp sclerites of Xenia grasshoffi Verseveldt, 1974 holotype (SMF 2616). a. Ellipsoid platelets, fractured; b. Sclerites with surface crest; c. Fractured sclerites composed of a latticework matrix of dendritic calcite rods radially arranged, at least in peripheral region; d. Overview of variety of sclerites. Scale bar at a, b and c 0.010 mm, at d 0.020 mm.