Keratoisis ramosa, Lapointe & Watling, 2022

Lapointe, Abby & Watling, Les, 2022, Towards a revision of the bamboo corals (Octocorallia): Part 5, new genera and species of Keratoisididae from the Tasmanian deep sea, Zootaxa 5168 (2), pp. 137-157 : 146-148

Keratoisis ramosa new species

Figures 9 , 10

Material Examined. Holotype: The Finger, Tasman Fracture Zone, Tasmanian Seamounts , TMAG K3847 , collected on 10 January 2009, -45.2958, 146.1144, 2898 m, 1.877° C bottom temp.

Diagnosis. Colony bushy and with multiple thin branches. Colony branches at the internodes, occasionally in a tripartite manner. Sclerites in the polyp body and coenenchyme are needles and rods, with a slight constriction, usually midway along the length, although the location may vary. Pharyngeal sclerites are toothed rods, significantly longer than wide, with several jagged calcium carbonate crystal extensions.

Description. Colony is bushy in appearance with branching originating at the internodes ( Fig. 9A, B ). Branches occasionally originating at a tripartite junction. The axis ranges from 7 mm in diameter at the base of the colony to 1 mm along the distal branches. The axis is solid in the larger branches, with a pin-size hollow core in the thinner, distal branches. Secondary calcification occurs over several of the nodes, especially at the base of the colony.

The distance between nodes is variable, ranging from 15 to 50 mm. Polyps are located on all sides of the axis, with large spacing among polyps. Polyps are tall, columnar, approximately 5 mm in length ( Fig. 9C, D ). Sclerites in the polyp body are rods, pointed rods, and needles, ranging in length from approximately 0.35 to 3.0 mm ( Fig. 10A ). Sclerites are arranged obliquely and horizontally at the base of the polyp, but longitudinally along one side of the polyp and surrounding the tentacles ( Fig. 9C, D ). Sclerites have a slight constriction that usually occurs midway, but may be located anywhere along the length of the sclerite ( Fig. 10A ). Rods and needles have longitudinal grooves and numerous tubercles on the ends. Scales are not present. Septal sclerites consist of eight individual or coupled protruding pointed rods, and may flare outward slightly when tentacles are contracted. When contracted, tentacles fold slightly inward with tips touching ( Fig. 9D ).

Sclerites are arranged mostly longitudinally throughout the coenenchyme, with some arranged obliquely, similar in size to the sclerites in the polyp body, but with a tendency to be more pointed and slender ( Fig. 10B ).

Tentacular sclerites are rods and flat rods, ranging from approximately 0.08 to 0.7 mm ( Fig. 10C ). The larger rods are arranged longitudinally along the aboral side of the tentacles, while the smaller rods are arranged horizontally from the tentacle base and into the pinnules.

Sclerites of the pharynx are irregular toothed rods, with a heavily textured surface composed of grooves and protuberances. Pharyngeal sclerites are significantly longer than they are wide and range in length from approximately 0.07 to 0.09 mm ( Fig. 10D ). Two pharyngeal sclerites are frequently fused together. Lateral teeth may be gently rounded or triangular. Many sharp calcium carbonate crystal extensions protrude from the sclerite teeth.

Etymology. The species name is based on the Latin adjective ramosis, = branchy, a reference to the many thin branches that comprise the colony.

Remarks. The shape of the sclerites in the polyp body, coenenchyme, and pharynx of K. ramosa are unique within the genus. Rods and needles in the polyp body and coenenchyme have a distinctive constriction, usually midway along the lengthy of the sclerite.

The conspicuous extensions of calcium carbonate on the pharyngeal sclerites has not been observed in any other species of Keratoisididae .

The mtMutS sequence of this species differs from that of K. fruticosa only at the 5’ end of the gene.

Figures

FIGURE 9. Keratoisis ramosa n. sp., holotype, K3847, A, all collected and preserved colony pieces, B, in situ view of colony being collected, C, D, views of individual polyps.

FIGURE 10. Keratoisis ramosa n. sp., holotype, K3847, sclerites from, A, polyp body, B, coenenchyme, C, tentacles, and D, pharynx.