Xenia novaebritanniae Ashworth, 1900

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 : 220-222

Xenia novaebritanniae Ashworth, 1900

Figs. 11 , 12

Xenia novaebritanniae Ashworth, 1900: 521–522 , plate 52–53, Figs. 1–3 , 5–9

Xenia novaebritanniae ; Benayahu 1990: 115, table 1, listed only; Reinicke 1997: 40–41

Material. Syntype: X. novaebritanniae BML 1962.7 .20.148, South Pacific Ocean , Lifu, Loyalty Island, November 1896 , Syntype: BML 1962.7 .20.149, Papua New Guinea, New Britain, Talili Bay , 1895 .

Description. The syntype BML 1962.7.20.148 is 30 mm high; its stalk is 10 mm long and about 10 mm wide at its base and 20 mm wide at the uppermost part. The colony was cut into two more or less identical parts. There is a small fragment under the same collection number. The polyp body is up to 3 mm long, and the tentacles are up to 2 mm long, featuring two rows of pinnules on each side. The pinnules are short and stout, up to 0.2 mm long and 0.2 mm wide, 9–10 in the outermost row with no gap to occasionally a gap of one pinnule-width between adjacent pinnules.

Sclerites are ellipsoid platelets, 0.013 –0.020 X 0.017 –0.024 mm in diameter ( Fig 11 , n=20). They are composed of calcite rods, uniform in width throughout their length. A fractured sclerite revealed that the rods are arranged radially at the periphery, occasionally branched at their distal end, but oriented randomly at the sclerite center ( Fig. 11c ). The sclerite surface is granular and often fractured.

The dimensions of BML 1962.7.20.149 correspond to those of the other syntype ( BML 1962.7.20.148). The polyp body is up to 2 mm long, and the tentacles are up to 3 mm long, featuring three and sometimes four rows of pinnules on each side. The pinnules are short and stout, up to 0.2 mm long and 0.2 mm wide, 10–14 in the outermost row with a gap of one pinnule-width between adjacent pinnules. Its sclerites are ellipsoid platelets, 0.012 –0.017 X 0.018 –0.022 mm in diameter ( Fig. 12a, n =20). They are composed of calcite rods ( Fig. 12c ). The granular surface of the sclerites is fractured.

Remarks. Ashworth (1900) described X. novaebritanniae as featuring three rows of pinnules with 8–12 in each row. Examination of BML 1962.7.20.148 revealed that it has only two rows of pinnules and thus does not belong to the species and was probably mislabeled. However, the original description closely corresponds to the current findings for BML 1962.7.20.149. Benayahu (1990) listed this species for the Red Sea, based on the original description. Reinicke (1997) examined the two syntypes and his description noted three and occasionally four rows of pinnules, 10–12 in the outermost row, similar to our description of BML 1962.7.20.149.

Similar species and conclusion. Both X. novaebritanniae and X. crassa feature three and occasionally four rows of pinnules and a similar number of pinnules in the outermost row (10–14 vs. 13–18); however, as X. crassa sclerites possess crests on their surface, the two species should be considered as separate.

Distribution. South Pacific Ocean: Loyalty Island, Papua New Guinea, New Britain, Red Sea.

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.

FIGURE 3. Scanning electron micrographs of polyp sclerites of Xenia blumi Schenk, 1896 holotype (SMF 44). a. Ellipsoid platelets, fractured; b. Fractured sclerite enlarged; c. Fractured sclerite composed of dendritic rods; d. Overview of sclerites. Scale bar at a, c and d 0.010 mm, at b 0.002 mm.

FIGURE 5. Scanning electron micrographs of polyp sclerites of Xenia crassa Schenk, 1896 holotype (SMF 39). a. Sclerites with a surface crest, fractured; b. Ellipsoid platelet, mostly fractured; c. Fractured sclerite composed of a latticework matrix of dendritic calcite rods and more or less radially arranged in the peripheral region. Arrows at b, c indicate surface furrow. Scale bar 0.010 mm.

FIGURE 6. Scanning electron micrographs of polyp sclerites of Xenia fusca Schenk, 1896 syntype (SMF 40). a. Ellipsoid platelets; b. Fractured sclerites composed of a latticework matrix of dendritic calcite rods and more or less radially arranged in the peripheral region; c. Overview of sclerites. Scale at a and c 0.010 mm, at b 0.002 mm.

FIGURE 7. Scanning electron micrographs of polyp sclerites of Xenia garciae Bourne, 1894 type (BML 1921.11.18.1). a. Sclerite with a surface crest, fractured; b. Ellipsoid sclerites, fractured c. Fractured sclerite composed of a latticework matrix of calcite rods, dendritic and sinuous and radially arranged in the peripheral region; d. Overview of sclerites, fractured. Scale bar at a, b and d 0.010 mm, at c 0.002 mm.

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.

FIGURE 9. Scanning electron micrographs of polyp sclerites of Xenia membranacea Schenk, 1896 syntype (SMF 41). a. Irregular sclerites with rough surface texture; b. Irregular sclerites with granular surface texture; c. Sclerites with surface crest, some fractured; d. Fractured sclerites composed of dendritic rods (enlarged). e. Ellipsoid platelets; f. Round sclerite; g. Fractured sclerite. Scale bar at a, b, c, e, f, g 0.010 mm, at d 0.002 mm.

FIGURE 11. Scanning electron micrographs of polyp sclerites of Xenia novaebritanniae Schenk, 1896 syntype (BML 1962.7.20.148). a. Ellipsoid platelets, fractured; b. Fractured sclerite; c. Fractured sclerites enlarged composed of a latticework matrix of calcite rods, dendritic and sinuous, radially arranged in peripheral region. Scale bar at a and b 0.010 mm, at c 0.002 mm.

FIGURE 12. Scanning electron micrographs of polyp sclerites of Xenia novaebritanniae Schenck, 1896 syntype (BMNH 1962.7.20.149). a. Ellipsoid platelets, fractured; b. Fractured sclerites; c. Fractured sclerite enlarged, composed of calcite rods. Scale bar at a and b 0.010 mm, at c 0.002 mm.