Parastenella pacifica Cairns, 2007

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 : 243-246

Parastenella pacifica Cairns, 2007 Figures 36A, B , 37 A–C , 38 A–E

Parastenella pacifica Cairns, 2007b: 526, 527; figs 1C; 8, 9.

Type locality.

USA, Oregon, west of Cape Meares, 45°25'18"N, 125°11'01"W, 1498-1527 m.

Type specimen.

Holotype USNM 1071799 [dry]; type was not examined.

Material examined.

1 lot (see Appendix 3: List of material examined).

Description.

Colony ( Figure 36A ) with dichotomous branching, somewhat irregular, generally in one plane; some SBMNH specimens slightly bushy, flabellate, up to +30 cm in height (next largest, 14 cm tall). In largest colonies branchlet tips tend to droop down, curling slightly back on themselves ( Figure 36A ); branching intervals vary from ~3.5 cm distance at lower end of main stem (near base) to less than 1.0 cm near branch/branchlet tips. Polyps ( Figure 36B ) with opercula well differentiated; usually spaced 0.5-1.5 mm apart in/as singles, pairs or whorls of up to three, erect (perpendicular to axis), or slightly bent downward toward stem. Polyp height 2.0-3.5 cm, flared distally with slender, delicate stalk, heavily armored with calcareous scales. Polyps found on numerous branches, tending to favor one side of colony. Axis as described for family; visible through single layer of white, translucent coenenchymal scales; dark to light brown in color. Color of living colony (?)cream or white; in alcohol, cream to light tan. Sclerites are scales ( Figures 37 A–C , 38 A–E ); marginal scales (standard number eight) alternating in position from opercular scales (latter forming distinct operculum, creating obvious projection out from polyp). Marginal scales (Figures 37Aa, 37B, 38C) all of similar shape and size, most showing broad, shallow apical flute; these generate symmetrical rosette when viewed from above. Submarginal body wall scales (Figures 37Ab, 38A) roughly arranged in eight longitudinal rows, each row with three to four scales that appear to overlap those in adjacent rows; distal end obviously rounded, no fluting apparent; flutes absent on submarginal abaxial body wall scales. Otherwise, polyp completely covered with body wall scales, including adaxial region. Opercular scales (Figures 37Ac, 37C, 38D) alternate with marginal scales (as opposed to overlapping them) around polyp; triangular shape, prominently keeled on inner surface; most all of similar size (0.5 mm in length, on average). Coenenchymal scales ( Figure 38B , possibly) generally elliptical, very evident on branches (resembling sea pansy rachis or water lily pad), in one thin layer; few with irregular shape. Pinnular sclerites ( Figure 38E ) small rods, with granular surface.

Etymology.

The species name pacifica - in reference to its general location; stated to be closely similar to Parastenella atlantica ( Cairns (2007b). Cairns suggested that these could form a geminate (twin species) pair, differing largely in having ranges in different oceans. The species designation is listed as accepted in WoRMS Database (Cordeiro et al. 2019)

Distribution.

Deep-water species (~1,500-2,086 m, currently known to live on the continental slope off Oregon up to British Columbia (Queen Charlotte Islands); see Appendix 3: List of material examined. Material in the SBMNH collection came from an area north of the California Bight’s northern limit; whether it will be found further south (into the California Bight) remains to be seen.

Biology.

Of the many fragments/partial colonies present in the one lot from the SBMNH collection, one of the fragments has bits of a distinguishable, pale orange ophiuroid (brittle/basket star) intertwined/tangled within it. This could either be an artifact of collection or a true living condition. The specimen from Moss Landing Marine Labs (see Appendix 3: List of material examined) also showed presence of Ophiuroidea; based on the nature of their location, etc. within the colony, likely a living situation, not an artifact.

Remarks.

Sclerites in specimens from SBMNH were consistently a bit smaller than those from holotype shown in Cairns (2007b). Furthermore, the SBMNH material not generally in good condition; was often difficult to get good microscopic arrays showing enough of the different forms of body wall scales (abaxials, laterals and adaxials) so as to see clear differences. The coenenchymal sclerites on branches were very evident, however, and examination of sclerites showed clearly the broad, shallow fluting. While tentacular rods are considered common in this species, sometimes very few would be found in the fragments examined; the condition of many of the polyps may partly explain their absence. Further examination of undamaged colonies, collected from the same area, may better reveal their presence.

Figures

Figure 9. Swiftia simplex, specimen 81 - 99 B- 1 (Alaska Fisheries Service), light microscopy arrays. A 4 x magnification, showing long, slender spindles and anthocodial fingerbiscuit-rods B 10 x magnification of sclerites, emphasizing fingerbiscuit-rods of anthocodium. These rods measure between 340 - 350 µm, while long, thin spindles measure between 430 - 500 µm. Specimen provided by Bob Stone, Alaska Fisheries Service.

Figure 36. Parastenella pacifica, SBMNH 422983. A Colony (attachment base missing), ~ 15 cm x 13 cm, at widest point B Branch tip close-up.

Figure 37. Parastenella pacifica, SBMNH 422983. Light microscopy arrays, scleritic scales. A An assortment a possible marginal scale b abaxial body wall scale c opercular scale B 10 x-magnified image; marginal scale C 10 x-magnified image; opercular scale.

Figure 38. Parastenella pacifica, SBMNH 422983, SEM image. A Abaxial body wall scales B Coenenchymal scale C Marginal scales D Opercular scales E Pinnular sclerites. Compare to those shown in Cairns 2007 (Figure 9).