Gersemia lambi, Williams, Gary C., 2013

Williams, Gary C., 2013, New taxa and revisionary systematics of alcyonacean octocorals from the Pacific coast of North America (Cnidaria, Anthozoa), ZooKeys 283, pp. 15-42 : 24-27

Gersemia lambi sp. n. Figures 7-11, 19

Species diagnosis.

Polyps clustered in groups on short lobes, emanating from short stalk above holdfast. Polyps tubular, curved, non-retractile, relatively large. Sclerites primarily radiates with variable ornamentation and modification of turberculation; rod-like forms also present. Colonies pink in life, white preserved.

Type material.

Holotype. CAS 171939, Canada, British Columbia, Langara Island; 26 June 2004; 12 m depth, collected by Andy Lamb; one specimen. Paratypes. CAS 171940, same data as holotype, one specimen. CAS 171940, same data as holotype, one specimen.

Additional material.

CAS 179449, same data as holotype, 11 specimens. CAS 173218. Canada, British Columbia, east side of Kerouard Island, off south end of Queen Charlotte Island; 9 m depth, 51 54.624'N, 130 58.635'N; 7 August 2003; 20 m depth; collected by Doug Swanston; one specimen. CAS 173219. Canada, British Columbia, Queen Charlotte Islands, Kunghit Island, west side of Cape St. James; 21 May 2002; 9 m depth; collected by Danny Kent; one specimen.

Habitat and distribution

(Figure 19). Shallow subtidal region from Cape Ommaney, southeast Alaska, USA (according to Neil McDaniel, pers. comm.), to central British Columbia, Canada; 9-20 m depth.

Etymology.

This species is named for marine naturalist and educator Andy Lamb (Vancouver, British Columbia), who collected the type material.

Description.

Colonial morphology (Figures 7B-C). The holotype measures 55 mm in length, 39 mm in width, and 35 mm in height. It is composed of dense concentrations of autozooids distributed in isolated clusters on several lobes that emanate from the stalk, which arises immediately above the basal holdfast. Each cluster usually contains approximately 5 and 15 polyps.

Polyps (Figures 7 B–C, F). The polyps are monomorphic, non-retractile, tubular in shape, and vary in length and width (4.0-7.0 mm in length and 1.5-2.0 mm in width). The width of the polyps is greatest at the distal extremities. The polyps are erect and often curve upward from their bases.

Sclerites (Figures 8-11). Coenenchymal sclerites of the polypary are primarily sharply-tuberculated radiates, 0.03-0.11 mm. Coenenchymal sclerites of the stalk are mostly variously-ornamented radiates and modified radiates, 0.03-0.12 mm long. Polyp wall sclerites abundant, uniformly and densely-distributed, 0.03-013 mm in length, mostly variably-shaped radiates and rods with a few irregularly-shaped elongate forms and crosses. Tentacle sclerites densely and uniformly distributed (not arranged en chevron), mostly radiates and rods, although a few club-shaped or approach torch-like forms are also present.

Color (Figures 7 A–D, E). Colony color is pink to reddish in life, often with orange oral discs. Colonies are uniformly cream-white in color when preserved in ethanol.

Differential diagnosis.

The only other species known in the genus Gersemia from the Pacific Coast of North America is Gersemia juliepackardae Williams & Lundsten, 2009. Although coenenchymal sclerites of the two species are predominantly eight radiates, Gersemia juliepackardae and Gersemia lambi sp. n. differ markedly in surface feature characters. Those of Gersemia juliepackardae are narrow with slender medial waists and relatively rounded tubercle tips ( Williams and Lundsten 2009), while those of Gersemia lambi sp. n. are broad with wide medial waists and more acute tubercle apexes (Figures 8-11).

This species is distributed from Washington to southern California, while Gersemia lambi is known from southern Alaska to British Columbia. The two species differ markedly in their bathymetric distributions. Collected material of Gersemia juliepackardae is recorded between 888 to 1600 meters in depth, although video images record the species from 520-2034 meters ( Williams and Lundsten 2009). Gersemia lambi sp. n., on the other hand, is known at present only from a depth range of 9-20 meters.

Key to the species of Gersemia from the west coast of North America