Placogorgia species A

Horvath, Elizabeth Anne, 2019, A review of gorgonian coral species (Cnidaria, Octocorallia, Alcyonacea) held in the Santa Barbara Museum of Natural History research collection: focus on species from Scleraxonia, Holaxonia, Calcaxonia - Part II: Species of Holaxonia, families Gorgoniidae and Plexauridae, ZooKeys 860, pp. 67-182 : 67

Placogorgia species A Figures 49, 50A, B, 51 A–C, 52 A–G

Type locality and type specimens.

Until there is species confirmation, no information can be provided.

Material examined.

~5 lots (see Appendix 1: List of material examined). While labeled Placogorgia material was examined at NMNH, nothing resembled in any way the specimens in the SBMNH collection.

Description.

Colony (Figures 49, 50A) generally branched in one plane; rarely, few reticulate; colony height (base to tip of upper-most branch) approximately 20-21 cm.; long, generally dichotomous branches and branchlets, moderately thick, cylindrical; branch diameter thickness averages 5.0 mm (including calyces); meandering sinuously, branches bent upward, parallel with main stem (not always obvious); tips of branches and branchlets swollen, to rounded 8.0-mm diameter (Figure 50B). Main stem bifurcates (sometimes), some distance ( ± 10 cm) from base; branches then again bifurcate at ~1.0->5.0 cm from first division. Further branching asymmetrical. Not all branches subdivide; of those that do, distance from previous subdivision varies. Polyps distributed over entire surface, sparsely placed at base, becoming progressively most crowded at branch tips. Color of freshly collected specimens, via video and still image (Figure 49), pale pinkish tan with conspicuous, fluffy, cotton candy-pink polyps; in preserved (dry) specimens, color dull tan-brown (Figure 50A, B); axis color slightly darker brown. Calyces moderately low, ~1.0 mm tall, 2.0 mm across, 2.5 mm apart; blunt/rounded, conical, armed with sclerites of various shape. Coenenchyme (relatively thin) contains long, blunt-ending spindles, often bent; largest bent spindles 0.3-0.6 mm L, 0.05-0.1 mm H (average 0.5 mm L × 0.08 mm H), often with strong external spines (Figure 52D). Distinctive sclerites often like thorn-scales or thorn-stars; small, spinulate or laciniate ones predominantly calycular (Figures 52 E–G). Anthocodial sclerites difficult to extract; sclerites of collaret also blunt-ended, bent spindles, at base of polyp, tending to circular arrangement. A few as large, heavy, tapered spindles, sometimes with several heavy, rough spines projecting from one side; some few (the calycular sclerites) as branched torches (Figure 52B); also, crutch-types (Figures 51A, 52C); some few as crosses and irregular ones, most as unilateral spiny shapes (Figure 51B, C). Color of sclerites cream to very light tan, at least in specimens that are long dry.

Distribution.

For genus (based on material found/examined at NMNH and other institutions, such as CAS) from Point Conception (California Bight) to Gulf of California (eastern North Pacific Ocean); western Pacific from Hawaii south to Philippines and Indonesia. NMNH also has specimens in this genus collected from off the coast of Chile in the southeastern Pacific Ocean; these look very different from the one described here.

Biology.

May be considered a subtidal to deep-sea genus; this based on collection data for known species.

Remarks.

Bayer’s review of the genus (1959b), and description of a new species from Florida, was invaluable for understanding the SBMNH specimens; a thorough discussion of both the calycular thorn scales and the cortical sclerites was provided. For specimens described here, the calycular thorn scales were difficult to extract; most of the material studied was quite dry, but an examination of wet specimens (SBMNH 422968 and 422970) revealed that the form labeled “E” in Bayer (1959) is the closest fit to what is seen in these specimens. Cortical sclerites in these specimens best fit those labeled “K,” “L,” and “M” (latter, in part; Bayer 1959). As well, sclerites seen in these specimens also corresponded as follows to Diechmann’s (1936) illustrations for several species in the genus Placogorgia from the Atlantic Ocean: pl 15, figs 19-20 best match those identified as cortical thorn scales, pl 15, figs 23-24 best match those likely calycular (branched torch) thorn scales, while pl 15, figs 26 and 32 match the blunt-ended spindles seen here. Nearly all sclerite shapes in this unidentified species are far broader in their root than they are tall; based on interpretation of the key in Bayer’s review I have made a tentative placement of this species in the genus Placogorgia .

There are multiple species of Placogorgia from the Atlantic, as well as a number of species from the South Pacific and Indian Oceans ( Kükenthal 1924). Only a few records were found from the southeastern Pacific: unidentified species found west of southern Chile (USNM 80162 [wet] and 98863 [wet]), and a number of unidentified specimens from the western North Pacific (Hawaii), such as USNM 75077; none were from the eastern North Pacific. There was one reference by Harden (1979) indicating that the species, using one of the same specimens currently discussed here (SBMNH 422969), is Placogorgia ramosa ( Wright and Studer 1889), stating that it is synonymous with Paramuricea ramosa (Wright & Studer, 1889). Cordeiro et al. (2018i) does not list a species P. ramosa in the list of recognized Placogorgia species in the WoRMS Database; Harden’s designation does not inform the identification of the SBMNH specimen in any way. As well, I could not find any other indication that Paramuricea ramosa is synonymous with Placogorgia ramosa .

Muzik (1979) stated that coenenchyme in species of Placogorgia is filled with diverse spindles that are simple, branched and often flattened, occasionally with one or more projections; this is descriptive of what was seen here. Muzik (1979) also stated that the calycular thorn scales are wider than tall, the projection usually short, with the base broad and flat. The Hawaiian species described by Muzik (1979) with their distinctive features were of interest: the presence of 1) broad calycal thorn scales and 2) very branched, flattened sclerites of the coenenchyme. It seemed best to place the examined specimens in the SBMNH collection within the genus Placogorgia based on the appearance of the sclerites, but other genera are under consideration. However, any link between an eastern Pacific locality and described members of this genus, or any other possible genera, cannot be made ( Ekman 1935: 66, 1953: 40; Bayer and Deichmann 1960).

Should specimens in the SBMNH collection represent a new species, this would be the first description of a species from this genus in the northeastern Pacific Ocean; if not a new species, then this is the first record of a known species of Placogorgia (seen elsewhere) from the northeastern Pacific Ocean; further study of specimens is currently underway.