Zoologische Mededelingen, 83 (September 2009)G.C. Williams; L. Lundsten: The nephtheid soft coral genus Gersemia Marenzeller, 1878, with the description of a new species from the northeast Pacific and a review of two additional species (Octocorallia: Alcyonacea)

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Systematics

Class Anthozoa Ehrenberg, 1831

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Subclass Octocorallia Haeckel, 1866

Order Alcyonacea Lamouroux, 1812

Family Nephtheidae Gray, 1862

Gersemia Marenzeller, 1878

Description.― Colonies erect, arborescent from one main stalk. Polyps relatively congested at the ends of short and narrow terminal branches, an effect that is observed more readily in wet preserved specimens. Polyps non-retractile with calyces, supporting bundles of polyps, and polyp crowns absent. Polyp points present: the polyp walls and tentacle rachises usually with numerous sclerites. Points of the polyp walls sometimes arranged more-or-less en chevron. Stalk sclerite complement commonly includes modified or irregularly-shaped capstan-like structures. Sclerites often coloured. Species azooxanthellate. Worldwide distribution in temperate to polar regions, mostly in colder waters, up to over 1200 meters in depth.

Type species.― Gersemia loricata Marenzeller, 1878: 377.

Gersemia juliepackardae spec. nov.

(figs 2, 3, 4A-B, 5, 6, 7)

Material examined.― Holotype CASIZ 175883; Sample Number T1101-A4; U.S.A., central California, Pioneer Seamount (37.37255 N 123.403252 W); 1004.9 m; 19.vi.2007; MBARI - David A. Clague; one whole specimen attached to a fragment of dead sponge. Paratype CASIZ 175884; Sample Number V3191-A1; U.S.A., central California, Monterey Canyon (36.720495° N 122.005016° W); 1186 m; 10.iv.2008; MBARI - James P. Barry; one whole specimen removed from granitic rock substratum. Paratype RMNH Coel. 39007; Sample Number T1100-A12; U.S.A., central California, Pioneer Seamount (37.368573° N 123.39311° W); 1253 m; 18.vi.2007; MBARI - David A. Clague; one fragment sampled from volcanic lava substratum.

Other material: CASIZ 175885; Sample Number T661-A2; U.S.A., southern California, Rodriguez Seamount (34.055796° N 121.084348° W); 889 m; 28.iv.2004; MBARI - David A. Clague; one fragment sampled from volcanic lava substratum. CASIZ 134171; Field Number OTB-500; U.S.A., central Oregon, off shore (43.00° 21.60’ N; 125.00° 10.20’ W); 1600 m; 4.iv.1973; A. Carey Jr. on board R/V Cayuse via trawl; ca. 12 whole specimens. CASIZ 179446; Container Number 779; U.S.A., northern Washington, Olympic Coast National Marine Sanctuary (47° 51.412’ N 125° 28.363’ W); 879 m; 11.vii.2008; National Oceanic and Atmospheric Administration; four whole specimens attached to a rock.

Description of the holotype growth form.― The colony is attached to a fragment of dead hexactinellid sponge. The preserved and contracted holotype is 88 mm in length and 41 mm in width. Basal stalk width at proximal portion of holdfast approximately 40 mm. Lateral branching begins immediately above the holdfast into two mostly opposite rows of primary lateral branches. The primary branches each give rise to several smaller or secondary branches toward their distal ends.

Polyps.― Polyps mostly concentrated on the outer edges of ultimate branches. Some polyps occur on the primary branches in groups of two or more. Polyps are not retractile but tentacles are retractable into the body of each polyp. Polyps are tubular/cylindrical, mostly 4.5-5.5 mm long by 1.2-1.5 mm wide. Some of the smallest (presumably younger) polyps are approximately 1.5 mm in length. The distal half of polyps that contains the anthocodia are bulbous, more or less oval in shape, salmon pink in colour, and 2.3-3.0 mm long. Distal half of each polyp with eight en chevron points composed of salmon pink sclerites, distinct crown not developed (fig. 4A). The basal halves of polyps are white and mostly tubular. Tentacles with rods and spindles arranged en chevron along the longitudinal median (fig. 4B).

Sclerites.― Sclerites include spindles, club-shaped spindles, needles, branched needles; branched club-shaped spindles; and branched spindles. Polyp body wall sclerites are needles and spindles 0.09-0.51 mm (figs 5B, 6A-K). Tentacle sclerites are mostly irregularly-shaped rods and stout spindles 0.08-0.22 mm (figs 5A, 6L-N). Branched spindles of the tentacles are rare to infrequent in abundance. One end of branching sclerites are weakly bifurcate or trifurcate. Surface of the upper stalk contains eight radiates with some irregular radiates; rarely seven radiates 0.06-0.10 mm (figs 5C, 7A-H). Sclerites of the interior of the middle to upper portions of the stalk absent. Surface of the basal portion of the stalk with eight radiates 0.10-0.12 mm (figs 5D, 7I-P). Rod-like sclerites of the interior of the base of the stalk at the holdfast level extremely sparse.

Colour.― Coloration of the tentacles and the distal regions of the polyps (anthocodiae) is salmon pink; basal portion of polyps white; the holdfast and lower region of the stalk are white; the branches of the stalk and the middle to upper parts of stalk are pale pink. The coloration is permanent and was observed in situ (figs. 2, 3), and in all preserved specimens as well, including those collected in 1973.

Etymology.― The new species is named in honour of Julie Packard, executive director of the Monterey Bay Aquarium, Monterey, California, for her dedication to ocean stewardship and conservation, and for elevating public awareness about the ocean environment.

Distribution of collected specimens.— Rodriguez Seamount (southern California) to northern Washington (fig. 1); 888-1600 meters depth. Of the five specimens collected using ROVs, four were collected from hard rock substrata. One other specimen, the holotype, was collected from where it was attached to a dead hexactinellid sponge. The trawled material, CASIZ 134171, came from unknown habitat type on the continental shelf off central Oregon.

Distribution of material from video images presumed to be of the new species.― San Juan Seamount (southern California) to northern California (fig. 1); 520-2034 meters depth. Of the 230 individuals that were observed in video only (i.e., no specimen was collected) and identified as Gersemia juliepackardae by the second author, the vast majority (95%) were observed on hard-rock substrate including volcanic lavas, outcropping granite, outcropping bedded sandstone, and talus material from volcanic and granitic sources. In addition, several individuals of G. juliepackardae (4.4%) were observed upon either dead or living hexactinellid sponge. Only one organism was observed living upon soft sediment, but it is assumed that this organism was attached to a small rock below the sediment surface as has been observed for other deep-sea corals. Ancillary data that were collected by the ROV during video observations indicate that this species may occupy a temperature range of 1.98 – 6.13 °C (mean 3.86 ± 0.025 SE, n=235), a salinity range of 34.17 – 34.59 psu (mean 34.44 ± 0.008 SE, n=235), and oxygen concentrations of 0.21 – 1.42 mL/L (mean 0.52 ± 0.009 SE, n=235). Video transect length (mean 143.8 m ± 21.75 SE, n=6) and width (mean 0.91 m ± 0.14 SE, n=6) varied. Organism density ranged from 0.0 – 0.28 individuals m^-2 (mean 0.09 individuals m^-2 ± 0.05 SE, n=6).

Variability.― One Oregon specimen (CAS 134171) has numerous sclerites in the interior of the base of the stalk (the region just above the holdfast). These sclerites are rod-like with robust, thornlike, elongated tubercles.

Remarks.― Until now only three species have originally been described in the genus Gersemia: Gersemia loricata Marenzeller, 1879 (type species) from the Arctic Ocean, G. marenzelleri Kükenthal, 1906b, from the Sea of Japan, and G. subtilis Tixier-Durivault, 1961, from the tropical Atlantic Ocean. Other species that are possibly assignable to the genus Gersemia have been described in various genera including Alcyonium, Eunephthya, Nephthea, Paraspongodes, and Voeringia. Gersemia juliepackardae spec. nov. differs from the previously described species of Gersemia as follows. Polyps of the new species have eight points but no crown development (fig. 4A), whereas the polyps of G. subtilis have well-developed crown and points (Tixier-Durivault, 1961: 246, fig. 11f). Stalk sclerites of the new species are mostly eight radiates and 0.07-0.12 mm long, while stalk sclerites of G. marenzelleri are spindles and clubs 0.12-0.20 in length (Kükenthal, 1906b: 287), and those of G. loricata are robust spindles and rods (Marenzeller, 1878: pl. 3, fig. 3A). Eunephthya antarctica Kükenthal, 1906a superficially resembles Gersemia juliepackardae spec. nov. (Kükenthal, 1906a: pl. 3, figs. 14, 15), but the new species differs in having eight radiates in the stalk, whereas the sclerites of E. antarctica are mostly rods and robust spindles with pronounced tubercles (Kükenthal, 1906a: pl. 12, figs. 73, 74).

Gersemia, Litophyton, and Alcyonium

(figs 4C-D)

Gersemia liltvedi (Verseveldt & Williams, 1988), comb. nov.

Material examined.— CASIZ 108791; Litophyton sp.; Japan, Ryukyu Islands, Okinawa, Seragaki, 1.3 km ENE of Maekizaki (26.00˚ 30.40’N 127.00˚ 52.60’E); 58 m; 09.xi.1996; coll. R.F. Bolland, SCUBA; one whole specimen. CASIZ 167912; Gersemia liltvedi; South Africa, Cape Province, Port Elizabeth, Thunderbolt Reef, 21-24 m; 16.ii.1999; J. Starmer, SCUBA; one whole specimen.

A soft coral from South Africa was described as Litophyton liltvedi by Verseveldt & Williams (1988: 321; see also Williams, 1992: 337). Subsequent investigation has shown that the proper generic designation should be Gersemia. Species of Litophyton Forskǻl, 1775, have some sclerites of the branches and stalk that are spindles, often with spine ornamentation more pronounced on one side (= caterpillars) (fig. 4C; see also Fabricius & Alderslade, 2001: 106). Gersemia liltvedi comb. nov., differs in having stalk sclerites that are modified capstans (fig. 4D). Species of both genera do not have supporting bundles or crowns in the polyps. However, they differ as follows: Gersemia species are azooxanthellate, circumglobal temperate to polar, colder water taxa, that do not inhabit coral reefs; in mostly deeper water 21-1253 m (with video images depth is increased to 2034 m); sclerites are often coloured; the stalk usually has modified or irregularly-shaped capstan-like sclerites < 1 mm. On the other hand, Litophyton species are zooxanthellate, tropical, warmer water taxa that inhabit coral reef regions of the Indo-Pacific; in shallow water < 50 m; sclerites are colourless; some stalk sclerites are spindles > 0.1 mm. Taking this information into consideration, we here regard Gersemia liltvedi as the correct binomial designation for this taxon.

In addition, a species previously referred to by several authors as ‘‘Gersemia rubiformis’’ and the common name of ‘‘Sea Strawberry‘‘ from the Pacific northwest coast of North America (southern Alaska to northern California) is more correctly designated as an unidentified species of Alcyonium (Williams, 2007: 184-185, 188), and will be dealt with in a subsequent publication. The species can be aligned with other species in the genus Alcyonium due to its lobate growth form, the possession of crowded rounded lobules, small retractile polyps that can completely withdraw into the coenenchyme of the lobules and sclerites of densely warted spindles, radiates, and ovoid or clubbed forms similar to other species in the genus, such as Alcyonium gruveli Tixier-Durivault, 1955, A. monodi Tixier-Durivault, 1955, A. grandis Casas et al., 1997, A. southgeorgiensis Casas et al., 1997, and A. valdiviae Kükenthal, 1906 (Verseveldt & Ofwegen, 1992: 161-167; Casas et al., 1997: 304-310; Verseveldt & Williams, 1988: 316-321; Williams, 1992: 292-295).

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