Acanella aurelia, France, 2017

France, Scott C., 2017, A taxonomic review of the genus Acanella (Cnidaria: Octocorallia: Isididae) in the North Atlantic Ocean, with descriptions of two new species, Zootaxa 4323 (3), pp. 359-390 : 379

Acanella aurelia sp. nov.

Figures 13 and 14

Material examined: Holotype: Collected via trawl aboard R/ V Pelican, 250 km west of Clearwater , Florida, USA 27.7523, -85.3262. 657̄ 815 m depth. 7 July 2006 . Station NSF-III-0 72. Deposited in the National Museum of Natural History USNM 1416575 . GenBank accession # GQ245889 , KX 270218 .

Diagnosis: Acanella with upright (2̄ 3 mm) polyps with obliquely arranged, long (2̄ 3 mm), thick (100 µm) sclerites at the distal end of the polyp, which extend beyond base of contracted tentacles by up to 1 mm. Primary branching occurs at node in a whorl of two to four branches and secondary branching occurs dichotomously; nodes yellow-golden color.

Description: Colony bush-like with primary branching at nodes in a whorl of two to four branches and secondary dichotomous branching. Holotype is only a fragment of a colony, 5 cm tall and missing the base ( Figure 13 ). Internodes cream to white in color, thin and delicate, measuring 0.5̄ 2 cm in length with shorter internodes being found on the main axis at base of colony. Anastomosis of branches not observed. Nodes yellow to golden color and sclerite free. Axis covered by a thin translucent coenenchyme. Coenenchymal sclerites thin needles covered with small tubercles 100̄235 µm (n=75; mean=125 µm ± 0.1 µm) in length.

Polyps light yellow to cream (when preserved in ethanol) in color with darker concentration of color at the distal end ( Figure 14 ). Polyps arise at 90° from the axis and have a thin attachment point. Polyps tubular with a slight bulge in the middle where they are at their widest (1̄ 1.5 mm in diameter). A tall crown of needles at the oral end of the polyp is due to the intertentacular sclerites protruding up to 1 mm past the weakly contracted tentacles ( Figure 10 ). Polyp length varies from 2̄ 4 mm (n=27; mean= 2.4 mm ± 0.02 mm) and width varies from 0.4̄ 1 mm (n=27; mean= 0.76 mm ± 0.01 mm). Polyps sparse, with only one and rarely two polyps per internode, found on all sides of the branches and at the terminal ends of the branchlets.

Sclerites found in polyp body wall large and thick and range from 500 µm̄ 3 mm in length ( Figure 14 ). Smaller sclerites found densely packed at the base of the polyp and larger sclerites appear mid-polyp and twist obliquely up polyp body. Eight large sclerites protrude 1 mm past the base of the tentacles. Tentacles weakly contracted and fold over the oral disk. Sclerites along the backs of the tentacles range in size from 150̄300 µm (n=82; mean=167 µm ± 0.02 µm).

DNA sequences derived from mtMusS -5’ (GenBank accession # GQ245889 ) and 18S ( KX 270218 ) differ from other North Atlantic Acanella Haplotypes by at least 0.54% (7 nucleotide substitutions across 1277 sites).

Etymology: Named in honor of Aurelia Noel Saucier, who was born during the synthesis of this manuscript, and as an allusion to the yellow to golden nodes the coral possesses.

Remarks: This species is described from a single specimen collected by trawl in the Gulf of Mexico. It is the lone specimen in our collection with sequence Haplotype B. Morphologically it differs from A. arbuscula in that the polyps are not as tall and the intertentacular sclerites make up half the body length of the polyp.

Distribution: Gulf of Mexico, 657̄ 815 m depth.

Figures

FIGURE 10. SEM images of Acanella rigida (Haplotype E, CP 3652 / 3). A) Tentacle sclerites. B) Coenenchyme sclerites. C) Polyp body sclerites.

FIGURE 13. Acanella aurelia colony fragment (NSFIII 07223).

FIGURE 14. SEM images of Acanella aurelia (Haplotype B, NSFIII 07223). A) Tentacle sclerites. B) Coenenchyme sclerites. C) Polyp body sclerites.