Plumarella longispina Kinoshita, 1908

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 III: Suborder Holaxonia continued, and suborder Calcaxonia, ZooKeys 860, pp. 183-306 : 248-251

Plumarella longispina Kinoshita, 1908 Figures 39A, B , 40 A–H

Plumarella longispina Kinoshita, 1908a: 14, 15. Nutting 1909: 716. Kükenthal 1924: 260, 261.

Type locality.

N. Pacific Ocean, Japan, Honshu Island, Sagami Bay, Okinose Bank, 600 m.

Type specimens.

Holotype USNM 50117 [dry]; branch (from holotype), donated by Tokyo Imperial Museum; this material was examined. Main colony presumably still housed in collection at Tokyo Imperial Museum (all scientific and "natural materials" collections housed separately at what is now called the National Museum of Nature and Science); was unable to verify or confirm catalog number.

Material examined.

~33 lots (wet/dry) (see Appendix 3: List of material examined).

Description.

Colony ( Figure 39A ) exhibits dense, alternate, pinnate branching in one plane, leading to flabellate form. Main stem somewhat flattened, giving rise to alternate main branches at irregular distances; both main stem and branches may subdivide. Each main branch gives forth regularly alternate, slightly smaller branches that do not subdivide. Branchlets flattened, 1.5 mm thick ( Figure 39B ). Polyps small, short, cylindrical projections, 0.5 mm tall (to summit of operculum), 0.5 mm across, 1.5 mm apart; arranged laterally in two opposite rows on flattened stems, branches and branchlets; some polyps placed such that they project toward a front side of colony, with back of colony smooth; strictly alternate to strictly opposite in different parts of colony, with upper edge of one polyp ordinarily reaching to base of next one above. Polyp aperture pointed upward, slightly outward. Walls of polyps armed with sclerites; these conspicuous, flattened scales, vary greatly in size and form in different polyps. Color of colony (? alive) generally white; dry or in alcohol, dull creamy-white; some preserved colonies light grayish-brown, with surfaces of stem and branches being more distinctly gray. Sclerites ( Figure 40 A–H ) quite varied in form, generally more or less flattened into scales; thin, cycloid. Key characteristic sclerite a flattened basal portion bearing on its distal edge long thorn-like processes (spines) projecting above margin of polyp ( Figure 40E ). Many scales ornamented with convex, ctenate margin. Surfaces of scales ornamented with evenly, closely distributed granules, irregularly placed nodular warts and occasional spines. Typical arrangement of scales on polyp wall is eight lon gitudinal rows, each row having roughly four scales in a ring; two proximal rings composed of broad curved scales with their distal convex edges ctenate, distal-most marginal ring composed of scales (with no keel), bearing prominent thorn-like, unwarted spines extending beyond end of operculum. Marginal spines usually number from two to six, two of which (abaxial) are often distinctly longer than the others. Operculum composed of eight irregularly shaped scales, not keeled, points of which often joined into spine-like processes ( Figure 40 F–H ). Adcauline opercular scales reduced to nar row band, the antero-lateral processes from proximal rings of sclerites being the only ones that meet to complete the ring on abcauline side.

Etymology.

From the Latin, longi - = long and spina - = spine; long-spined, referencing the spinose marginal sclerites that extend beyond end of operculum on polyps.

Distribution.

Found off California coast between ~55-735 m. Of specimens examined, could not confirm that this species is found off the Oregon coast (thus far, all specimens examined were collected either from Baja California [Mexico] and California [USA] or Washington [USA]; it seems odd that it would skip an entire area between CA and WA). Based on material collected by staff of Olympic Coast National Marine Sanctuary (May, 2006 and July, 2008) that was examined, seen off northwest Washington coast at depths of at least ~208-309 m. Specimens from the genus have been taken in Alaskan waters (Bering Sea, etc.) in depths from 85-2514 m; collection data for these specimens can be found by doing a search of the online data base for the NMNH, Smithsonian, Invertebrate Collection. Listings of this particular species (by Wing and Barnard 2004; Heifetz et. al. 2005; and Stone and Shotwell 2007) mentioned in Cairns, 2011, could not be confirmed.

Biology.

Work by Lissner and Dorsey (1986) along Tanner and Cortes Banks and the Santa Rosa-Cortes Ridge area off southern California showed a depth range as follows: at depths <67 m the species is sparse, at depths ranging from 67-122 m the species is common to abundant, and at depths below 122 m, again becoming sparse. Deep-water video images taken by MBARI indicated the possibility of the genus (perhaps this species) being more common at greater depth (at least in some areas) than once thought.

In all specimens examined, only one had any other organism associated with it; on this specimen there appeared two anemones, both on branches near the tip. One, the larger of the two, is on the exposed axis. On this same specimen, on the area of branches just above the base, there appeared to be the anchor tendrils from the egg case of a shark. These tendrils are quite thin, but with the stiff curl they usually display. Egg cases were noticeable on specimens collected by OCNMS in May 2006. Colonies of this species are quite rigid, so it is likely that they provide good anchorage.

Remarks.

A key data point in the distribution of this species was Nutting’s specimen locality (1909): ‘Albatross’ station 4359, Point Loma light-house, 32°42'00"N, 117°14'00"W (N 85, E 9 miles), 191 fathoms (347 m). This specimen currently housed at NMNH (USNM 25429); specimen was examined.

In a comparison with a different species (from the Aleutian Islands, Plumarella spicata Nutting, 1912), it presented marginal scales that were similar in shape to those seen in this species, but the spinous process of the marginal scales in P. longispina are much less ornamented. As well, all of the operculars in the species described here display areas of surface that appear very smooth and undecorated; in P. spicata , surface ornamentation is more prevalent, although perhaps not continuous along entire surface. Colony form of P. spicata (delicate and flimsy, more or less dichotomously branched), does not match what is seen for this species.

Unless there are very subtle differences, e.g., characteristics that might specify several subspecies, this species seemed to be one of the most abundant deep-water prim noids occurring in the California Bight (and elsewhere). Its overall colony form is quite distinctive, and easily recognizable. While appearing to be quite delicate, closer examination and handling indicated that it is actually fairly hardy. In the near future, an examination of all specimens in the SBMNH collection will have to be undertaken, with special attention paid to any feature(s) that could be assessed as a key characteris tic that might show some degree of variability. The question arose as to whether there are transitional variations over the entire range of this species, and if so, whether those variations might subdivide the specimens, such that they point in the direction of distinct subspecies (or for that matter, species). Molecular studies on any of those groupings could add further clarity. However, it may be that this is simply an enormously successful species, thus very common, with adequate and successful dispersal abilities. Cordeiro et al. (2019) shows P. longispina with accepted species status.

Figures

Figure 5. Swiftia pacifica, specimen 41 - 39 - 1 (Alaska Fisheries Service, Gulf of Alaska); looking in same form of that seen in Figure 3, light microscopy arrays. A (4 x) showing variety of sclerites, particularly the characteristic " fingerbiscuit-rod " seen in the genus Swiftia. Sclerites from specimen examined for Bob Stone, Alaska Fisheries Service B Higher magnification, 10 x, showing all sclerite forms, including obvious anthocodial fingerbiscuit-rods. The larger spindles measure ~ 300 µm long, smaller spindles of ~ 200 µm, and the rods range from 308 - 370 µm in length.

Figure 39. Plumarella longispina, SBMNH 422394. A Colony, 14 cm tall x 15 cm wide B Branch tips. Scale bar: 2 cm (A).

Figure 40. Plumarella longispina, SBMNH 422394, SEM image. A, B Body wall scales C Flatter coenenchymal scales D Marginal scales E Marginal spinous sclerites F-H Opercular scales (worn). Compare / contrast these images with those shown in Cairns 2011 (Figure 5, P. spicata).