Dokidisis australis, 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 : 155-156

Dokidisis australis new species

Figure 15

Material Examined. Holotype: Tasman Fracture Zone, Outer Wall, Tasmanian Seamounts , TMAG K3834 , collected on 08 January 2009, -45.3742, 144.5933, 3256 m, 1.35° C bottom temp.

Diagnosis. With the characters of the genus.

Description of Holotype. Colony unbranched or forks once at the node, with a thick and robust axis ( Fig. 15A, B ). Only a portion of the colony was collected. The axis contains numerous longitudinal grooves and is 15 mm diameter at the basal section and 9 mm diameter in the distalmost portion of the colony. The hollow core is less than 1 mm in diameter at the base and increases slightly in diameter as the colony grows, reaching about 1 mm distally. Polyps are sparsely scattered on all sides of the axis, with large areas of thin coenenchyme between polyps. Sclerites in the polyp body are blunt rods, arranged longitudinally and obliquely ( Fig. 15C ). Rods may be slightly curved, club-shaped, and vary in width ( Fig. 15D ). Needles and scales are not present in the polyp body. Sclerites are sparsely and irregularly arranged throughout the coenenchyme in the form of flat rods, ranging in length from 0.14 to 0.26 mm ( Fig. 15E ). Small flat rods, similar to those in the coenenchyme, may be sparsely arranged at the base of the polyp body as well. Scales are not present in the coenenchyme.

Sclerites similar in shape to those in the polyp body but slightly smaller in size are arranged longitudinally along the aboral side (rachis) of the tentacles. Flat rods are arranged along the pinnules, perpendicular to the tentacle. Flat rods are decorated with numerous tubercles and longitudinal grooves ( Fig. 15F ).

Sclerites are very sparse in the pharynx, and several polyps had to be examined before any sclerites were found. The polyp pharynx lacks sclerites in the form of thorny rods or double stars. The two sclerites found in the pharynx were measured at 0.09 and 0.11 mm in length, with several longitudinal grooves and irregular borders ( Fig. 15G ). It is possible that the sclerites found in the pharynx may be contaminants produced during dissection.

Etymology. The species name is based on the Latin adjective australis = southern, a reference to the southern hemisphere where the specimen was collected.

Remarks. Dokidisis australis is similar to Jasonisis thresheri , a new genus and species recently described from Tasmania ( Alderslade and McFadden, 2012), in that both species branch at the node and lack intertentacular needles and pharyngeal sclerites in the form of thorny rods or double stars.

However, unlike J. thresheri , D. australis is not covered by a thick tegument and the blunt rods in the polyp body differ significantly from the densely-packed scales in Jasonisis . Besides the lack of pharyngeal sclerites, we could not determine a set of specific characters that would include D. australis in the genus Jasonisis , even though the two species are in the same large J clade (see Watling et al. 2022) ( Fig. 2 ). That clade has many morphologically diverse specimens within it and we suspect that with increased sampling the relationships of the several forms will become clear.

Figures

FIGURE 2. Cladogram of the Keratoisididae modified from Watling et al. (2022). New taxa added in this paper are in bold lettering. Bootstrap values>50 are shown above the nodes and Bayesian probability values>0.5 are shown below the nodes. Major clades are referred to by the designation along the right side of the cladogram.

FIGURE 15. Dokidisis australis n. sp. holotype K3834, A, all collected and preserved colony pieces, B, in situ view of colony, C, view of individual polyp, and sclerites of, D, polyp body and tentacle rachis, E, coenenchyme, F, tentacle pinnules, G, pharynx.