Plumarella williamsi Cairns & Rodriguez-Bermudez, 2024, sp. nov.
Creators: name: Cairns, Stephen D.
name: Rodriguez-Bermudez, Adriana
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Cnidaria
Anthozoa
Alcyonacea
Primnoidae
Plumarella
Plumarella williamsi

description: Plumarella williamsi, sp. nov.
Figs. 1A, 2A–G, 3A–E
Not Plumarella longispina Kinoshita, 1908: 14–15.— Kükenthal, 1919: 349–350; 1924: 255 (key), 260–261.
Plumarella longispina: Nutting, 1909: 716, pl. 88, figs. 1–2, pl. 90, fig. 3.— Etnoyer & Morgan, 2003: 22 (listed).—? Wing & Barnard, 2004: 24.— Cairns, 2007: 512 (in part: listing from California).— Whitmire & Clarke, 2007: 152 (listed).— Whitmire et al., 2017: 5 (listed).— Horvath, 2019: 256–260, 303–305, figs. 39–40.
Plumarella (Plumarella) longispina: Cairns, 2011: 8 (listed).
Material Examined. Holotype: Albatross 3664, dry colony and SEM stubs 2841, 2844, 2848–2849, USNM 49591. Paratypes: Albatross 3349, 38˚57’45”N, 124˚03’05”W (off Santa Catalina Island), 437 m, 25 Sept. 1890, 2 dry colonies, 3 colonies in alcohol, and SEM stub 2842, USNM 49585; Albatross 3664, see type locality, 2 colonies dry, USNM 1665990; Albatross 4359, 32˚N, 117˚W (off Point Loma, San Diego), 349 m, 15 Mar 1904, 1 specimen in alcohol, USNM 25429 (specimen reported by Nutting, 1909); Ropos 955-82, 48˚15’40”N, 125˚00’49”W (Cape Flattery, Washington), 282 m, 28 May 2006, 1 dry colony (USNM 1117119) and one in alcohol (USNM 1117110); Ropos 955-75, 48˚15’34”N, 125˚00’26’W (Cape Flattery, Washington), 198 m, 28 May 2006, 1 colony in alcohol, USNM 1117115; off Monterey Bay, California, 731 m, 9 July 1925, 2 dry colonies, USNM 77285; off Santa Catalina, California (topotypic), 155–183 m, 31 Jan 1974, 1 dry colony and SEM stub 2843, USNM 73755.
Type Locality. Albatross 3664: 33617’N, 118˚24’W (Dakins Cove, off Santa Catalina Island, Channel Islands, California), 8 Apr 1897, 146 m.
Description. Colonies branch in a uniplanar fashion and are often broader than tall. The holotype (Fig. 1A) measures 13.5 cm in height and 17.0 mm in width, but specimens are known up to 40 cm in height. Branching occurs in a somewhat irregular alternate-pinnate manner (Fig. 1A), the terminal branchlets not having the regularity of a comb-like structure common to many other species in the genus; terminal branchlets are of different lengths, ranging from 8–20 mm in length. When alive the colony is grey-brown (Nutting, 1909) or white (Horvath, 2019).
Polyps are densely arranged (i.e., 14–16 polyps per cm) in an alternating arrangement (Fig. 2A), and occasionally paired, always in the plane of the colony flabellum. The polyps are cylindrical, curved distally, and quite short (almost adnate in disposition, Fig. 2B), measuring only 0.50–0.80 mm in height (exclusive of the marginal spines, which can extend considerably beyond the operculum).
Each polyp is encased by eight opercular scales distally and a variable number of body wall scales (discussed below). The opercular scales (Fig. 3B) are isosceles triangular in shape, with a blunt tip and range from 0.25–0.50 mm in length, the size progressively decreasing from the abaxial to adaxial margin; their outer face is smooth distally and sparsely granular basally; their inner face is tuberculate proximally and smooth distally; they have a L:W of about 2.0. The four pairs of marginal scales (Fig. 3A) are polymorphic in shape and size. The abaxial and outer-lateral pairs of marginals range from 0.7 to 1.0 mm in height and are often broken during collection. Each marginal has a massive rectangular base up to 0.6 mm in width, which supports an elongate, cylindrical, pointed spine (Figs. 2B–G, 3A) that can be up to 0.6 mm in length, thus composing 60% of the length of the scale. The inner-lateral pair of marginals (Fig. 2D) are shorter, only about 0.55 mm in height, and have a much shorter distal spine. The adaxial pair of marginals (Figs. 2D–E) are small (0.23 mm wide x 0.18 mm tall), thin, rectangular (non-spinose) scales. The outer faces of all the marginals are smooth. Proximal to the marginal scales are a relatively small number of thick, curved body wall scales (Figs. 2F–G, 3C), also smooth in surface texture, often somewhat irregular in shape and having a ctenate distal edge. They measure up to 0.7 mm in height and are often wider than tall. In general, there are only 1–2 pairs of abaxial submarginal body wall scales, one pair of outer-laterals, 0–1 pair of inner-laterals, and one more pair of adaxials, resulting in a body wall scale formula of: 2-3: 2: 1-2: 2. Proximal to the lowest body wall scales are two robust, curved, crescentric-shaped scales that resemble infrabasal scales (Figs. 2D, G, 3E). They form a transition between the lower body wall scales and the coenenchymal scales. Like the body wall scales, the infrabasals also have a smooth outer face, and thus are interpreted as modified body wall scales, but do not contribute to the body wall scale formula because they consist of only two scales per polyp and are not aligned with any specific row of body wall scales.
The coenenchymal scales (Figs. 2B, G, 3D) are usually elongate, thick, and often have an irregular margin. They measure up to 1.05 mm in length, although most are less than 0.6 mm, and have an L:W of up to 3.4. Their outer faces are sparsely granular.
Remarks. It is not surprising that the east Pacific P. williamsi was described by Nutting (1909) and subsequently by others as the Japanese P. longispina Kinoshita, 1908 (Figs. 1B, 4), as they both have: elongate abaxial and outer-lateral marginal spines; similarly shaped, oriented, and sized polyps; and alternate-pinnate branching and polyp placement. Although it may be noted that Kükenthal (1919) included Nutting’s (1909) record of P. longispina with a question mark, but did not in 1924. Nonetheless, P. williamsi differs primarily in having fewer body wall sclerites in all four body wall positions, as well as lacking auxiliary adaxial scales. Furthermore, P. williamsi has: taller marginal scales and more massive abaxial body wall scales and infrabasal scales; occasionally paired polyps; much larger coenenchymal scales that are less granular; an irregularly pinnate branching structure (not comb-like); and unordered granules on the opercular scales. Indeed, the small number of body wall scales of this species, which can hardly be called rows, distinguishes it from all species in the genus.
Although this species was recently redescribed by Horvath (2019) under the name P. longispina, it is nonetheless herein again redescribed based on more extensive SEM observations and a reinterpretation of some of her data. For instance, her figure 40B, labelled body wall scales are probably coenenchymals; figure 40D, labelled marginals, are also coenenchymals; and figure 40H, labelled operculars, are probably submarginals. The scale bar for figure 40E is more likely 200 µm, not 100 µm.
Etymology. Named in honor of Gary C. Williams of the California Academy of Sciences, for his productive career in the study of Pennatulacea and Alcyonacea from off South Africa, the western Pacific and the northeast Pacific, as well as the Atlantic, Antarctic, New Zealand, and Indian Ocean.
Distribution. From Baja California to Washington (see Horvath, 2019 for 33 additional localities), although as noted by Horvath, no records are thus far reported from off Oregon, 55– 735 m.
description: Published as part of Cairns, Stephen D. & Rodriguez-Bermudez, Adriana, 2024, A new species of Plumarella (Octocorallia: Calcaxonia: Primnoidae) from the Northeast Pacific, and the redescription of Plumarella longispina Kinoshita, 1908, pp. 387-396 in Zootaxa 5477 (3) on pages 388-392, DOI: 10.11646/zootaxa.5477.3.8, http://zenodo.org/record/12733101