New primnoid genus and species (Alcyonacea: Primnoidae) from the southwestern Atlantic Stephen D. Cairns Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, U.S.A., e-mail: [email protected] PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 125(2):180–188. 2012. New primnoid genus and species (Alcyonacea: Primnoidae) from the southwestern Atlantic Stephen D. Cairns Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, U.S.A., e-mail: [email protected] Abstract.—A new genus and species of primnoid octocoral, Heptaprimnoa patagonica, is described from deep water from the cold temperate/ Subantarctic region off Argentina and Burdwood Bank. It is distinguished from other primnoid genera by having only seven rows of body wall scales. Keywords: Alcyonacea, Argentina, new genus, new species, Octocorallia, Primnoidae, Subantarctic As noted by Cairns & Bayer (2009), the a new species; Orejas et al. (2007), repro- Primnoidae is a large and diverse octoco- ductive habits of two species; Zapata- ral family, ranking fourth among the 44 Guardiola & Lo´pez-Gonza´lez (2009), two octocoral families in number of species, new species; Cairns & Bayer (2009), three and third in number of genera. Whereas new genera and two new subgenera; Zapa- the primnoids are cosmopolitan in distri- ta-Guardiola & Lo´pez-Gonza´lez (2010a), bution and occur over a depth range of 8– two new genera and species; Zapata-Guar- 5850 m, they are found primarily in deep diola & Lo´pez-Gonza´lez (2010b), four new water, and there seems to be a dispropor- species; Zapata-Guardiola & Lo´pez-Gon- tionate number of species and genera za´lez (2010c), a new genus; and Taylor et al. living in the Antarctic–Subantarctic region (2012), a new species and a revision of (see Appendix). Twenty-three of the 38 Thouarella. Based on unstudied museum primnoid genera (60.5%) and 58 of the 247 collections, it would appear that many taxa species (23.5%) occur in this southern remain to be described. region. Among the 23 genera, 14 are found exclusively in the Antarctic–Subant- arctic region; the species of four genera are Materials and Methods found primarily in this region; and some The specimens used in this study were species of another five genera occur there originally collected by the R/V Walther (see Appendix). The names of most of Herwig, now housed at the Zoological these species can be found in Cairns & Museum Hamburg (ZMH), and by the B/ Bayer (2009:Table 4), as updated in the O Miguel Oliver, now housed at the papers listed below. Museo Nacional de Ciencias Naturales Over the last decade there has been a de Madrid (MNCN) and National Muse- steady stream of publications, mostly tax- um of Natural History, Smithsonian onomic in nature, concerning Antarctic Institution, Washington, D.C. (USNM). primnoids. Over the last ten years the The terminology used in the description following papers have concerned Antarctic can be found in Bayer et al. (1983). The primnoids: Lo´pez-Gonza´lez et al. (2002), a SEM photomicrographs were taken by the new genus; Mellado et al. (2004), steroids author using a Zeiss EVO MA15 micro- from Dasystenella; Cairns & Bayer (2005), scope. The polyps were prepared by VOLUME 125, NUMBER 2 181 Fig. 1. Holotype of Heptaprimnoa patagonica, now in three pieces. removing them from the branch and start to disarticulate the polyp sclerites. immersing them in 50% commercial This was followed by immediate and bleach for 10 sec in order to remove the repeated rinsing with distilled water, and thin layer of tissue from the outer surfaces finally 95% ethanol. Polyps were attached of the sclerites but not long enough to to the SEM stub with Elmer’s glue. 182 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Fig. 2. Polyps from holotype of Heptaprimnoa patagonica. A, abaxial stereo view of polyp showing its broad abaxial body wall scales; B, oblique stereo opercular view of polyp showing seven outer lateral (OL) body wall scales and 2 small abaxial marginals between them; C, stereo opercular view of polyp; D, adaxial stereo view of polyp showing paired adaxial body wall scales, smaller irregularly arranged adaxial scales, and eight opercular scales (O). VOLUME 125, NUMBER 2 183 Fig. 3. Polyps from the holotype of Heptaprimnoa patagonica. A, seven opercular scales, pair in upper left stereo view illustrating prominent keel on inner surface, lower right scale from adaxial position; B, six abaxial body wall scales, small one being abaxial marginal. Sclerites were rendered in full strength individually transferred using a lightly commercial bleach, followed by repeated dampened fine paint brush to a double- rinsing in distilled water, 70% ethanol, sided carbon adhesive tab onto the SEM and finally 95% ethanol. Sclerites were stub. 184 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Fig. 4. Polyps from holotype of Heptaprimnoa patagonica. A, five inner and outer lateral body wall scales; B, four adaxial body wall scales; C, four scales from upper coenenchymal layer; D, three tuberculate spheroids from lower coenenchymal layer. VOLUME 125, NUMBER 2 185 The following abbreviations are used in Three other primnoid genera are similar to the text: L:W, ratio of length to width of a Heptaprimnoa in having a single row of sclerite; MNCN, Museo Nacional de adaxial body row scales: Perissogorgia Bayer Ciencias Naturales de Madrid; NMNH, & Stefani, 1989, Dasystenella Versluys, 1906, National Museum of Natural History, and Pseudoplumarella Ku¨kenthal, 1915. Smithsonian Institution, Washington, Perissogorgia differs in having only five D.C.; O, opercular scale; OL, outer lateral marginal scales (not eight) and only one body wall scale; SEM, scanning electron row of body wall scales (i.e., the abaxial, not microscope; USNM, United States Na- seven), resulting in a naked adaxial polyp tional Museum, Smithsonian Institution face. It also differs in having only one layer (now called the NMNH); WH,R/V and thus one type of coenenchymal scale. Walther Herwig; ZMH, Zoological Muse- Dasystenella has only five marginal scales um Hamburg. (not eight), which are spinose (not rounded), corresponding to only five (not seven) rows of body wall scales. Furthermore, Dasyste- Systematics nella has a bottlebrush arrangement of branches, and only one layer of coenenchy- Phylum Cnidaria mal scales. Finally, Pseudoplumarella has Class Anthozoa only 5–7 marginal scales (not eight) and only Subclass Octocorallia three (not seven) rows of body wall scales. Order Alcyonacea Furthermore, Pseudoplumarella has adnate- Family Primnoidae Milne Edwards, 1857 ly (not inclined) arranged polyps that are Heptaprimnoa, new genus arranged in an alternate biserial manner (not in whorls). It should be noted that the Diagnosis.—Colonies uniplanar, dichot- number of coenenchymal layers found in omously branched. Polyps arranged in primnoid genera received a very low consis- whorls, the polyps directed distally. Well- tency index in the phylogenetic analysis of developed operculum present; operculars Cairns & Bayer (2009), and, thus, should not strongly keeled. Eight marginal scales be used exclusively to differentiate among present, but only seven longitudinal rows genera. of body wall scales, the abaxial row being Distribution.—Southwest Atlantic off single (unpaired) and its scales being quite Argentina and Burdwood Bank, 265– broad. Marginals not folding over opercu- 1248 m. lum. Body wall and outer layer of coenen- Etymology.—From the Greek hepta (¼ chymal scales with smooth outer surface. seven), an allusion to the seven rows of Inner coenenchymal layer composed of longitudinal body wall scales þ Primnoa, small tuberculate spheroids. type genus of the family, named for Discussion.—Using the key to the prim- Prymno, one of the many deep-sea oceanic noid genera published by Cairns & Bayer mythological Greek nymphs. Gender: fem- (2009), Heptaprimnoa keys closest to the inine. Monotypic. southwestern Pacific genus Tokoprymno Type species.—Heptaprimnoa patagoni- Bayer, 1996. Heptaprimnoa, however, dif- ca, herein designated. fers in having whorled (not biserially arranged) polyps, a uniplanar (not bushy) colony, smooth (not radially ridged) outer Heptaprimnoa patagonica, new species surface of its scales, two (not one) layers of Figs. 1–4 dimorphic coenenchymal scales, and only seven (not eight) rows of longitudinal body Description.—Colonies uniplanar and wall scales. dichotomously branched, with relatively 186 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON long terminal branches. Holotype (WH 0.4 mm in width. Two or three pairs of 267) now in three pieces: a sparsely adaxial scales (Fig. 2D) similar in size and branched segment 22 cm in length, a shape to inner lateral scales, but proximal branched portion 17 cm in length termi- to these scales are a number of smaller nating in four end branchlets, and a (0.12–0.20 mm diameter), circular, irregu- branched portion 19 cm in length termi- larly arranged scales (Figs. 2D, 4B). As nating in six end branchlets (Fig. 1). with abaxial scales, all body wall scales Largest colony (USNM 1174977) 30 cm have a smooth outer surface and tubercu- in height, containing distal branches up to late inner surface. Marginal scales essen- 20 cm in length. Axis golden in color, up to tially not distinguishable from other body 1.8 mm in diameter. Colonies light brown wall scales, but in some cases marginals to off white. bear a low medial keel on their inner Polyps occur in closely spaced whorls surface. with little intervening coenenchyme, facing Opercular scales (Figs. 2C, D, 3A) upward; 8–10 polyps occur in each whorl; triangular in shape, 0.72–1.1 mm in length 3 whorls occur per cm; whorl diameter up (L:W ¼ 2.0–3.6). Longer opercular scales to 8 mm in most robust branch available. found on abaxial polyp side, these also Polyps cylindrical to slightly rectangular in having a lower L:W ratio due to their cross-section, up to 3.6 mm in length and broad base.