Nanipora kamurai, Miyazaki, Yu & Reimer, James Davis, 2015

Miyazaki, Yu & Reimer, James Davis, 2015, A new genus and species of octocoral with aragonite calcium-carbonate skeleton (Octocorallia, Helioporacea) from Okinawa, Japan, ZooKeys 511, pp. 1-23 : 6-11

Taxon classification Animalia Helioporacea Lithotelestidae

Nanipora kamurai sp. n. Figs 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11

Type material.

Holotype: NSMT-Co1562, Ama Beach, Zamami, Okinawa, JAPAN (26°13.31'N; 127°17.28'E), 1 m depth, collected by Yu Miyazaki (Y.M.), 16 July 2012, fixed in 99% EtOH, deposited in National Museum of Nature and Science, Tokyo, Japan (NSMT). GenBank accession numbers: mtMutS, KP195280; mt COI, KP195281; ITS1-5.8s-ITS2-28S, KP195282; Paratype 1: Specimen number RMNH 41731. Ama Beach, Zamami, Okinawa, JAPAN (26°23'N; 127°29'E), 1 m depth, collected by Yu Miyazaki (Y.M.), 16 July 2012, fixed in 99% EtOH, deposited in Naturalis Biodiversity Center, Leiden, the Netherlands (RMNH). Paratype 2: USNM 1231377, Ama Beach, Zamami, Okinawa, JAPAN (26°23'N; 127°29'E), 1 m depth, collected by Yu Miyazaki (Y.M.), 16 July 2012, fixed in 99% EtOH, deposited in National Museum of Natural History, Smithsonian Institution, Washington, D.C., USA (USNM); Other materials. Specimen number MISE-MY-120715. Ama Beach, Zamami, Okinawa, JAPAN (26°23'N; 127°29'E), 1 m depth, collected by Yu Miyazaki (Y.M.), 15 July 2012, fixed in 99% EtOH.

Description.

The holotype colony is encrusting (Fig. 1A), attached to the bottom (=downward facing side) of carbonate stone of dimensions 80 × 50 × 50 mm. Colony occasionally with thin stolons (2-3 mm in width, less than 1 mm thick) growing over irregular surface (Fig. 1B, arrow). The polyps of holotype colony are completely withdrawn into calyces after fixation.

Tentacles are 3-4 mm long, with fine but distinct pinnules (Fig. 2A and B). Anthocodiae are fully retractile within calyces. Coenenchyme is thin (up to 3 mm, less than 1 mm in most portions). Both coenenchyme and calyces are rigid with internal skeletons.

Overall shape of the skeleton is virtually the same as the external shape of living colonies (Fig. 3). Calyces are cylindrical, up to 1 mm across; up to 5 mm in height, perforated by randomly distributed pores up to 50 μm in diameter (Fig. 4). The surface of the skeletal calyx is occasionally wrinkled (Fig. 4, 5). The top of the calyces are serrated, with usually 16, but as many as 20 indentations (Fig. 6). Inside of the calyces is simple and tubular, lacking any structures such as septae. Calicular walls are 0.08-0.1 mm thick at the apical end and gradually became thicker going down towards the proximal portion, where thicknesses reached up to 0.2 mm. In the calicular walls, from distal to proximal portions, 12-20 cavities up to 0.05 mm diameter pass through (Fig. 7). These cavities are often discontinuous, converged or branched.

The whole skeleton has a reticulate pattern on the surface (Fig. 3, 4). This pattern is made by numerous tiny pores (up to 5 μm in diameter, Fig. 5); darker parts with pores, and lighter parts without pores. The surface calcium carbonate of the darker portions is very thin like a sheet, compared to the part without pores (Fig. 8). Growing edges of colonies and tops of calyces tend to lack such calcium-carbonate sheets and therefore the surface of these regions has holes (up to 200 μm, Fig. 9 A–D). In the cross sections of the coenenchymal skeleton, cavities 0.1-0.2 mm in diameter are observed (Fig. 10). These cavities house solenia, connecting the gastric cavities of polyps and composing solenial network (Fig. 11, 3-dimensional CT images of soft tissue). Lacks sclerites. Azooxanthellate.

Colour. Living colony is pale brown or ivory (Fig. 1A and B). Whole polyps are pale brown, but shrunken tentacles appear dark brown (Fig. 1B). Skeleton is colourless.

Etymology.

Named after Hidefumi Kamura, a great jazz pianist who has continued playing classic style be-bop jazz from when Okinawa was under the rule of U.S. forces, and who can now be considered as a ‘relict’ classical be-bop jazz musician.

Habitat.

Nanipora kamurai colonies are found on the bottoms (=downward facing sides) of carbonate stones on a sandy shallow beach at 1-1.5 m depths with very clear water. For now known only from Ama Beach, Zamami Island, Okinawa, Japan.

Comparison with other species.

General morphology of Nanipora kamurai is quite similar to Epiphaxum Lonsdale, 1850. Unlike Epiphaxum species, presence of sclerites not observed by any means in any portion of specimen in this study. Secondary daughter calyces, such as seen in Primnoa gracilis Nielsen, 1925 (= Epiphaxum auloporoides ) and Verrill’s original drawing of Lithotelesto micropora Bayer & Muzik, 1977 (= Epiphaxum micropora ), are not observed. Pores perforating calicular walls of Nanipora kamurai are distributed irregularly, not aligned in a line or in a row as seen in Epiphaxum species ( Bayer and Muzik 1977; Bayer 1992; Lozouet and Molodtsova 2008). Neither an octagonal outline in the cross sections of calyces, such as seen in Epiphaxum breve Bayer, 1992, nor sclerosepta as seen in Epiphaxum septifer , are observed.

Skeleton.

Examination of SEM images clearly showed the rigid skeleton of this species was not formed by fused sclerites as in Tubipora , but made of unitary calcium carbonate as in Heliopora . X-ray diffraction analyses revealed this skeleton was composed of 96% aragonite and 4% low-Mg calcite. Inclusion of traces of calcite may be contamination from calcareous algae attached to the surface of the colony. The skeleton of blue coral Heliopora coerulea , analyzed for comparison, was 100% aragonite.

Molecular phylogeny.

The four specimens of Nanipora kamurai in this study had completely identical mtMutS, COI and ITS1-5.8s-ITS2-28S sequences. In the ML trees for mtMutS (Fig. 12) and COI (not shown) alignments, the sequences of Nanipora kamurai in this study and Heliopora coerulea formed a strongly supported clade (ML=99% for mtMutS; ML=90% for COI) to the exclusion of all other octocoral sequences, and sequences of the new specimens formed a subclade clearly different from Heliopora (ML=100% in mtMutS, ML=100% in COI). p-distances between Nanipora kamurai and Heliopora coerulea were 0.053 (mtMutS) and 0.034 (COI), while distances between Nanipora kamurai and other soft corals included in phylogenetic analyses were at least>0.061 (mtMutS) and>0.042 (COI). ITS1-5.8s-ITS2-28S sequences of the unknown octocoral and Heliopora coerulea could be aligned together, but they could not be accurately aligned with any other known octocoral ITS1-5.8s-ITS2-28S sequences due to sequence divergence. The nuclear ITS1-5.8s-ITS2-28S region sequence of Nanipora kamurai had 94 nucleotide differences from Heliopora coerulea sequences over 697 nucleotides (=13.5% variation).

Remarks.

The distribution of Nanipora gen. n. is currently known from only one site in Okinawa. Although the lack of reports may result from their tiny size and cryptic habitat, considering the sporadic distribution and extraordinary rarity of related Epiphaxum spp., Nanipora kamurai may also be a relict species surviving with a very limited distribution. This species is one of the few exceptional species with an aragonite calcium-carbonate skeleton among Octocorallia.

Common Japanese name.

Zamami-ishi-hanagoke.