Anthoptilum gowlettholmesae, Williams, Gary C. & Alderslade, Philip, 2011

Williams, Gary C. & Alderslade, Philip, 2011, Three new species of pennatulacean octocorals with the ability to attach to rocky substrata (Cnidaria: Anthozoa: Pennatulacea), Zootaxa 3001, pp. 33-48 : 39-42

publication ID	https://doi.org/ 10.5281/zenodo.200521
DOI	https://doi.org/10.5281/zenodo.6186537
persistent identifier	https://treatment.plazi.org/id/FC569472-DE65-1F34-77F3-FF07FC66FC3D
treatment provided by	Plazi
scientific name	Anthoptilum gowlettholmesae
status	sp. nov.

Treatment

Anthoptilum gowlettholmesae View in CoL sp. nov.

Figs. 4–5 View FIGURE 4 View FIGURE 5 , 7 View FIGURE 7. A B, 8A,B,E, 9, 10

Material examined. HOLOTYPE: TMAG K3876, Cruise TN 228, Dive J2-387, sample 012-005, ROV Jason , RV Thomas T. Thompson, 26 December 2008, Australia, Tasmanian Seamounts Marine Reserve (Location: Hill Z40), 44° 38.2’S, 147° 26.3’E, 1776 m depth, one whole specimen collected by slurp gun, 370 mm in length. PARATYPES: TMAG K3877, Cruise TN 228, Dive J2-382, sample 005-001, ROV Jason , RV Thomas T. Thompson, 17 December 2008, Australia, outside Huon Commonwealth Marine Reserve (Location: A1), 44°33.4’S, 147° 28.1’E, 1441 m depth, one whole specimen collected by coral grab, 410 mm in length; TMAG K3878, Cruise TN 228, Dive J2-393, sample 008-001, ROV Jason , RV Thomas T. Thompson, 12 January 2009, Australia, Tasman Fracture Zone (Location: The Knob), 45° 14.3’S, 145° 98.5’E, 1613 m depth, one whole specimen collected by bio grab, 350 mm in length; CAS 179452, Cruise TN 228, Dive J2-386, sample 001-001, ROV Jason , RV Thomas T. Thompson, 24 December 2008, Australia, Tasmanian Sea Mounts Marine Reserve (Location: Mongrel), 44° 25.04’S, 147° 26.33’E, 1109 m depth, one whole specimen collected by coral grab, 430 mm in length.

Diagnosis. Ratio of total colony length to rachis diameter circa 30:1. Autozooids up to 50 mm in length, crowded along rachis in oblique rows, 4–9 per row. Proximal terminus of peduncle sucker-shaped, hemispherical in life, with a proximally protruding, conical, terminal knob covering the end of the axis.

Description. The holotype is 370 mm long ( Fig. 4 View FIGURE 4 C), with the 300 mm rachis occupying 81% of the total length. The autozooids originate directly from surface of the rachis and measure 3–8 mm wide and up to 50 mm long, and are disposed in two series of oblique rows along the lateral sides, 6–10 per row. Polyp bodies are tubular, narrow elongate, up 35 mm long, with tentacles up to 15 mm long bearing numerous, narrow, elongate pinnules, 1.5 –2.0 mm long. Siphonozooids are abundant and crowded, approximately 0.25 mm in diameter, forming round to slightly oval hemispheres on two sides of the rachis between the autozooid bases. The peduncle is 70 mm long, occupying 19% of the colony, and the proximal portion is significantly enlarged with an expanded coenenchymal sheath immediately above a conical terminal bulb ( Fig. 4 View FIGURE 4 C, 8E). No sclerites were found in numerous samples taken throughout the colony. The rachis and peduncle in the wet-preserved holotype are tan, while the autozooids are dark purplish brown ( Fig. 4 View FIGURE 4 C).

Variability. The four wet-preserved specimens examined vary from 370 to 430 mm in length. The autozooids vary from 20 to 50 mm in length and are often up to 5 mm in diameter proximally. The oblique rows are relatively easy to distinguish, and contain 4–9 autozooids each. In life, paratype TMAG K3878 was deep yellow to orange with bright red-orange autozooids ( Fig. 4 View FIGURE 4 A). The wet-preserved paratype TMAG K3877 is tan to light maroon with deep purplish brown autozooids ( Fig. 4 View FIGURE 4 B), and paratype CAS 179452 is pale tan throughout (not figured).

Etymology. This species is named for Karen Gowlett-Holmes, who had been endeavouring to collect specimens of it for several years.

Distribution. South Tasman Rise (southwest of Tasmania, Australia); 729–1803 m in depth ( Figs. 9 View FIGURE 9 , 10 View FIGURE 10 ).

Differential diagnosis. The only other species in the genus that has a similar gross morphology (i.e. robust with a thick rachis densely covered with large autozooids) is A. grandiflorum . In that species the wet-preserved autozooids are usually circa 8–25 mm long and 2–3 mm wide and there are 5–10 in each oblique row. However, the oblique rows of some specimens are often not distinguishable or are difficult to distinguish since the autozooids are often extremely crowded, appearing more-or-less longitudinally disposed along the length of the rachis. On the other hand, in Anthoptilum gowlettholmesae sp. nov., the wet-preserved autozooids can be 20–50 mm long and 3– 5 mm wide, and there are 4–9 in each well defined oblique row. The new species is also more robust, up to 440 mm long, with a rachis 15 mm in diameter, giving a ratio of colony length to rachis diameter of up to 30:1 compared to 100:1 for A. grandiflorum . Additionally, the interior of the peduncle of A. grandiflorum contains sparsely distributed sclerites, which are minute ovals <0.03 mm long, but no sclerites have been found in A. gowlettholmesae sp. nov.

Remarks. Numerous individuals of an echinoid identified by K. Gowlett-Holmes as Dermechinus horridus (Agassiz, 1879) (family Echinidae ) were photographed beside a colony of Anthoptilum gowlettholmesae sp. nov. on a rocky outcrop in the Tasmanian Sea Mounts Marine Reserve ( Fig. 5 View FIGURE 5 B).