Diplopathes tuatoruensis, Opresko & Stewart & Voza & Tracey & Brugler, 2022

Opresko, Dennis M., Stewart, Rob, Voza, Tatiana, Tracey, Di & Brugler, Mercer R., 2022, New genus and species of black coral from the SW Pacific and Antarctica (Cnidaria: Anthozoa: Antipatharia: Schizopathidae), Zootaxa 5169 (1), pp. 31-48 : 40-44

Diplopathes tuatoruensis sp. nov. Opresko & Tracey

( Figs 1 , 5 )

Material examined. Holotype: NIWA 16055 , Stn TAN0413/68, 37.471 S, 177.205 E, Bay of Plenty, Tuatoru Knoll, off the northeast coast of the North Island of New Zealand, 200–295 m, 11 November 2004 ( USNM SEM stub 295; Genbank ON572255 ) . Paratype: NIWA 41698 , Stn TAN0802/302, 67.135 S, 171.144 E, Admiralty Seamount, 897–996 m, 13 March 2008 .

Type locality. Tuatoru Knoll, Bay of Plenty, off the northeast coast of the North Island of New Zealand; 200– 295 m.

Distribution. Bay of Plenty; Admiralty Seamount ( Fig. 1 ); 200– 996 m.

Diagnosis. Corallum planar, sparsely branched to the first order, rarely more; pinnules bilateral and alternating, mostly 5–7 cm long (maximum 10 cm); pinnular density 14–16 per 3 cm (total for both rows); polypar spines up to 0.045 mm tall; abpolypar spines up to 0.04 mm tall; 5–7 spines per mm in each row; polyps 2.8–3.2 mm in transverse diameter; polyp density 3–4 per cm.

Description. The holotype (NIWA 16055) is 29 cm tall and about 16 cm wide ( Fig. 5A ). The stem extends to top of corallum and has a diameter of 2.5 mm just above the base. Branching is to the first order only, mostly in one plane, but with overlapping branches. The branches are formed from elongated pinnules that become pinnulated themselves. The longest branch is 20 cm and 2.2 mm in diameter at the proximal end. The pinnules are arranged bilaterally and alternately, and over almost all of the corallum there are only two rows of pinnules; however, very rarely, an extra pinnule occurs on one or the other side of the axis, thus forming a pair, the members of which are slightly offset from one another. Pinnules are mostly 4‒5 mm apart in each row, with 14‒16 (total for both rows) per 3 cm, and 23‒27 pinnules per 5 cm of branch length. The pinnules are mostly 5‒7 cm in length (maximum 10 cm) and about 0.6 mm in diameter near the proximal end. They are inclined distally (distal angle formed with the stem about 60‒75); and the interior angle formed by the two rows of pinnules is close to 180 at their points of insertion.

The spines ( Fig. 5C ) are simple, triangular, smooth, laterally compressed, and flared out along the axis proximally and distally, almost forming ridges (most notable on the thicker parts of the pinnules); apex acute to slightly rounded. Spines stand out at right angles to the pinnular axis. On pinnules 0.12‒0.15 mm in diameter, polypar spines are 0.03‒ 0.04 mm tall, abpolypar spines 0.026 ‒0.036 mm tall. The spines are arranged in longitudinal rows, three to six of which can be seen in one lateral view. Within each row the spines are 0.11‒0.20 mm apart, resulting in 6‒8 per mm. On pinnules 0.23‒0.26 mm in diameter, the polypar spines are 0.035 ‒0.045 mm tall; abpolypar spines 0.028 ‒0.040 mm tall; spines 0.13‒0.29 mm apart (5‒7 per mm); five to six rows visible in lateral view. Rows of spines appear to be more crowded together on one side of axis on some parts of the pinnules.

The polyps ( Fig. 5B ) are 2.8‒3.2 mm in transverse diameter (measured from the distal side of the distal lateral tentacles to the proximal side of the proximal lateral tentacles). They are uniserially arranged on the upper or lateral side of pinnules leaving one side of corallum without polyps. The density of the polyps is 3‒4 per cm.

The paratype ( NIWA 41698 ) is very similar to the holotype in size, branching and pinnulation. The stem extends to the top of the corallum and is about 33 cm long. Branching is mostly to the first order .

Comparisons. As noted above, D. tuatoruensis resembles D. antarctica in density of branching, but differs in having longer and slightly less crowded pinnules, and smaller and more crowded spines ( Table 3 ).

Genetic Distances. A K2P-based genetic distance analysis based on cox3-cox1 indicated that D. tuatoruensis (NIWA 16055) is genetically 1.29% and 1.73% removed from D. multipinnata (NIWA 88617) and D. antarctica (NIWA 38070), respectively. This is reflected morphologically in the fact that D. tuatoruensis differs from the other two species in the length of the pinnules, the size of the spines, and in the size of the polyps ( Table 3 ).

Etymology. The species name is in reference to the type locality, Tuatoru Knoll in the Bay of Plenty.

Figures

FIGURE 1. Distribution of the three described species.

FIGURE 5. Diplopathes gen. nov. tuatoruensis sp. nov., holotype, NIWA 16055: A. corallum; B. polyps; C. sections of pinnules showing spines (B and C from schizoholotype, USNM SEM stub 295). The larger projections on the right side of the pinnules are the polypar spines.