INTRODUCTION
Octocorals in the genus Callogorgia Gray, 1858, as other primnoid corals (family Primnoidae), are important habitat-forming organisms in the deep sea (Etnoyer & Warrenchuk, Reference Etnoyer and Warrenchuk2007; Carreiro-Silva et al., Reference Carreiro-Silva, Braga-Henriques, Sampaio, Matos, Porteiro and Ocaña2011; Angeletti et al., Reference Angeletti, Argnani, Bakran-Petricioli, Canese, Ceregato, Foglini, Mastrototaro, Taviani and Trincardi2014). Their tridimensional structure allows them to shelter other species (Roberts et al., Reference Roberts, Wheeler and Freiwald2006), creating habitat for other invertebrates and fish (Cairns & Bayer, Reference Cairns, Bayer, Felder and Camp2009; Quattrini et al., Reference Quattrini, Georgian, Byrnes, Stevens, Falco and Cordes2013). Thus, species of Callogorgia are considered key species in these environments (Etnoyer & Morgan Reference Etnoyer and Morgan2003; Angeletti et al., Reference Angeletti, Argnani, Bakran-Petricioli, Canese, Ceregato, Foglini, Mastrototaro, Taviani and Trincardi2014).
The genus Callogorgia counts on 24 described species, distributed in the north Atlantic, Indo-Pacific (Cairns, Reference Cairns2010) and Mediterranean (Vafidis et al., Reference Vafidis, Koukouras and Voultsiadou-Koukoura1994), at depths ranging 37–2472 m. It is a well-established genus that in the past four decades has been the focus of two reviews: Bayer (Reference Bayer1982) and Cairns & Bayer (Reference Cairns and Bayer2002). Bayer (Reference Bayer1982) studied mainly species from the Indo-Pacific, and suggested that the genus could be divided in two groups, based on the sculpture of scales in the body wall. The study by Cairns & Bayer (Reference Cairns and Bayer2002) focused on western Atlantic species, with the description of two new species: C. linguimaris Cairns & Bayer, Reference Cairns and Bayer2002 and C. americana Cairns & Bayer, Reference Cairns and Bayer2002 (later synonymized with Callogorgia gilberti Nutting, 1908 by Cairns (Reference Cairns2010)).
Here we describe a new species of Callogorgia and we also propose the revalidation of Callogorgia americana. These new records represent the first of the genus in the south-western Atlantic Ocean.
MATERIALS AND METHODS
The examined specimens were sampled by several collection methods during three scientific expeditions realized in the western Atlantic between the years 1958–2011, at depths ranging 137–461 m (Table 1). Specimens are preserved in ethanol (70%) and kept at the National Museum of Natural History (NMNH) in Washington, DC (USA), and in the Museu Nacional do Rio de Janeiro (MNRJ), in Brazil. Terminologies follow Bayer (Reference Bayer1982), Bayer et al. (Reference Bayer, Grasshoff and Verseveldt1983) and Cairns & Cairns (Reference Cairns and Bayer2002). Digital images of sclerites were obtained partly by the SEM Laboratory, Smithsonian Institution (see Bayer et al., Reference Bayer, Grasshoff and Verseveldt1983 for details), and partly by the RTSC at Universidade Federal de Pernambuco, using an FEI–Aspex Express scanning electron microscope. Preparation of sclerites for imaging follow a standard protocol which is well described by Pante & Watling (Reference Pante and Watling2012).
Sample stations of Callogorgia spp. in south-western Atlantic Ocean. U.S.F.W.S.: United States Fish and Wildlife Service; P.C.A.T.C.B.P.: Projeto de Caracterização Ambiental do Talude Continental na Bacia Potiguar (Petrobras).
Abbreviations
Museums: USNM: United States National Museum (now the National Museum of Natural History or NMHN); MNRJ: Museu Nacional, Universidade Federal do Rio de Janeiro, Brazil.
Cruises: U.S.F.W.S.: United States Fish and Wildlife Service; P.C.A.T.C.B.P.: Projeto de Caracterização Ambiental do Talude Continental na Bacia Potiguar (Petrobras).
Morphological: BW: body wall; OL: outer lateral; IL: inner lateral; H:W: ratio between height and width.
RESULTS
SYSTEMATICS
Order ALCYONACEA Lamouroux, 1812
Suborder CALCAXONIA Grasshoff, 1999
Family PRIMNOIDAE Milne Edwards, 1857
Genus Callogorgia Gray, 1858
DIAGNOSIS
Colonies uniplanar, branchlets usually alternate pinnate in arrangement, but may also be opposite pinnate and dichotomous. Polyps arranged in whorls, the polyps facing upward. Polyps protected by eight longitudinal rows of scales, the rows decreasing in number of scales in the abaxial to adaxial direction, such that adaxial side may be largely naked. Outer surface of body wall scales smooth, granular, or ornately ridged, the ridges sometimes continuing to inner proximal side of scale. Marginal scales fixed, not folding over operculars, the latter bearing keels or ridges on their inner surface. Coenenchymal scales elongate and usually granular (Cairns, Reference Cairns2010).
TYPE SPECIES
Gorgonia verticillata Pallas, 1766, by monotypy.
REMARKS
Five species of Callogorgia are currently recorded for the western Atlantic, including the new species described herein (Figure 1). Previously to this study, Callogorgia was only known in the north-west Atlantic, Indo-Pacific and Mediterranean Sea. This study extends the latitudinal range of the genus to south Atlantic waters.
Distribution map of Callogorgia spp. in Western Atlantic, based on Cairns & Bayer (Reference Cairns and Bayer2002), Quattrini et al. (Reference Quattrini, Georgian, Byrnes, Stevens, Falco and Cordes2013) and present study. Filled circles: C. americana; open circles: C. gracilis; triangle: C. linguimaris; filled square: C. delta; open square: C. arawak sp. nov.
Callogorgia arawak sp. nov.
(Figures 2A, B, D, 3A–D & 4)
Colonies of Callogorgia spp. from Western Atlantic. (A) C. arawak sp. nov. (USNM 51257, holotype); (B) C. arawak sp. nov. (MNRJ 8563, paratype); (C) C. americana (MNRJ 8564); (D) C. arawak (USNM 52945, paratype). Scale bar: 10 mm.
Whorls and polyps of: (A–B): Callogorgia arawak sp. nov. (USNM 51257, holotype); (C–D): C. arawak sp. nov. (MNRJ 8563, paratype); E, F: C. americana (MNRJ 8564). Scale bars: A–C, E–F, 1 mm; D, 0.5 mm.
Sclerites of Callogorgia arawak sp. nov. (USNM 51257, holotype). (A–C, E): opercular scales; (D): body wall scalles; (F): coenenchymal scales. Scale bars: 0.1 mm.
Callogorgia verticillata: Bayer, Reference Bayer1961: 297 (in part: USNM 51257)
TYPE MATERIAL
Holotype: USNM 51257, 07°25′N 54°35′W, Surinam, 137–146 m (main stem 11 cm tall with 3 major lateral branches and part of holdfast) (Figure 2A).
Paratypes: USNM 52945, 21°04′N 86°19′W, Yucatán, 330–365 m (a main trunk lacking holdfast, with two major branches and numerous pinnate branchlets) (Figure 2D); USNM 52939, 20°55′N 86°28′W, Yucatán, 220–175 m (one pinnate branch 6 cm long with 3 branchlets on each side); USNM 52936, 07°28′N 55°11′W, Surinam, 137 m; MNRJ 8563, 04°45′S 36°11′W, Potiguar Basin (Rio Grande do Norte State), 423–461 m (one branch with a terminal bifurcation) (Figure 2B).
DIAGNOSIS
Alternately pinnate colonies with sometimes one but commonly two scales in outer-lateral row on one or both sides, 8–11 scales in abaxial rows, inner laterals always absent; body scales externally sculptured by radial wrinkles strongest along proximal edge and not anastomosing.
Description of the holotype: Colony of the general aspect of Callogorgia gracilis Milne Edwards & Haime, 1857, alternately pinnate, the major axis bending only slightly away from the origin of branchlets, hence nearly or quite straight; the branchlets are mostly 40–50 mm long when fully developed, 6–12 mm apart on each side of the stem (11 cm tall) (Figure 2A, B). Polyps are about 1 mm tall or slightly less, arranged in whorls of 3–5, of which 7–9 occur in 1 cm of axial length. The abaxial scale rows have 8–11 scales each, sculptured with moderately prominent radial wrinkles that are strongest and ridgelike where the scale is overlapped by the one below, interlocking with the radial ridges of its overlapping distal margin (Figure 3A–D). The outer-lateral rows always are present and commonly represented by two scales, but occasionally 0–2 are missing on one or both sides of a polyp (Figure 3A–D); they are not so strongly sculptured as the abaxials and the external ridges are confined to that part of the scale that is covered by the edge of the adjacent abaxials. A small, discoidal marginal (Adax-1) is present in both adaxial rows (Figure 3A–C). The operculars are smaller than those of other western Atlantic species of Callogorgia, at most about 0.4 mm tall, apically pointed but not projecting as a distinct stout tooth (Figure 4A–C), the inner surface of the abaxials and laterals with a rather low keel having two or three finely serrate ridges, the outer surface with an indistinct apical groove having two or three serrate ridges along the bottom, the margin finely serrate, and the base tuberculate (Figure 4D). The coenenchymal sclerites are thick, elongate, irregularly polygonal plates closely fitted together by their serrate margins, their outer surfaces glossy but sculptured by low to moderate reticulating ridges, their inner surfaces closely covered by complex tubercles (Figure 4F). Sclerites are glassy clear but the inner surfaces appear frosted because of the crowded tuberculate sculpture.
The axis is strongly calcified, irregularly grooved longitudinally, with a pale bronze or golden lustre that is paler in the branchlets, where it resembles mother-of-pearl, darker in the proximal parts of the axis. The holdfast is thickened by opaque white secondary calcareous deposits.
ETYMOLOGY
Arawak, the name of an Amerindian Neolithic people of the Guyanas and northern South American. A noun in apposition.
VARIATION
The two colonies from the coast of Surinam and the one from Brazil correspond rather closely. However, two specimens from near Arrowsmith Bank off the east coast of Yucatan agree in most salient points but have somewhat larger opercular scales, and somewhat more strongly sculptured abaxial scales. In Yucatan specimens, radial wrinkles of abaxials, apparently, not always reach the distal margin, unlike the Brazilian specimen. The abaxial opercular scales of this have an apical tooth with ridges slightly more prominent. It seems likely that Yucatan specimens represent the same species as those from Surinam and Brazil, but they may constitute a subspecifically distinct northern population. Unfortunately, the amount of material available for study is so small that it is undesirable to formalize subtaxa at this time.
COMPARISON
Callogorgia arawak sp. nov. differs from all other western Atlantic species in the large number of scales (8–11) in the abaxial rows, the presence of two scales in the outer-lateral rows of many if not most polyps, the external sculpture of radial wrinkles showing little or no anastomosis, and the smaller opercular scales with poorly developed apical tooth. The species virtually more similar to C. arawak sp. nov. is C. gracilis, which however, besides the differences mentioned above, have the outer face of abaxial scales with radially anastomosed sculpture (honeycombed aspect). A comparison between characters of Callogorgia spp. in the western Atlantic is given in Table 2.
Distinguishing characters of the Western Atlantic Callogorgia. BW: body wall; OL: outer lateral; IL: inner lateral; H:W: ratio between height and width.
DISTRIBUTION
Western Atlantic, including Yucatan, Surinam and northern Brazil 137–365 m. No records in intermediate localities.
COMMENSALS
Both specimens from Surinam (USNM 51257, 52936) and the larger one from Yucatan (USNM 52945) have ophiuroid commensals (Figure 2D).
Callogorgia americana Cairns & Bayer (Reference Cairns and Bayer2002)
(Figures 2C, 3E, F & 5)
Polyp and scales of Callogorgia americana (MNRJ 8564). (A) lateral view of polyp; (B, C) opercular scales; (D, G–H) body wall scales; (E, F) coenenchymal scales. Scale bars: A, 0.5 mm; B–C, 0.16 mm; D, G–H, 0.13 mm; F, 0.1 mm.
Callogorgia americana americana Cairns & Bayer, Reference Cairns and Bayer2002: 845–852, Figures 1A & 2–4, Table 1 (synonymic list); Reference Cairns, Bayer, Felder and Camp2009a: 29, Table 4 (listed); Reference Cairns and Bayer2009b: 329 (listed). –Quattrini et al., Reference Quattrini, Georgian, Byrnes, Stevens, Falco and Cordes2013: 4129, Figure 2D–F.
Non Callogorgia americana delta Cairns & Bayer, Reference Cairns and Bayer2002: 852–856, Figures 1B & 4–6; Reference Cairns, Bayer, Felder and Camp2009a: 29, Table 4 (listed); Reference Cairns and Bayer2009b: 329 (listed).
MATERIAL
MNRJ 8564, 04°37′S 36°46′W, Potiguar Basin (Rio Grande do Norte State), 137–215 (2 fragments) (Figure 2C).
DESCRIPTION
Fragments of plumose, slightly flexible, uniplanar and pinnate colonies, up to 19.5 cm in height. Main stem with 1–2 mm in diameter. Branchlets up to 8 cm in length and distances between branchlets in one side 9–15 mm (Figure 2C). Polyps arranged in whorls or isolated on the main stem (Figure 3E, F). Whorls usually in 5/cm with 3–5 polyps (commonly 4), 1 mm in length each (Figure 3E, F). Eight opercular scales, 0.37–0.61 mm high and apical tooth slightly projecting (Figure 5B). Presence of 7–10 abaxial pairs, 2–4 OW, 1–2 IL and 1–2 pairs less developed in adaxial row (Figures 3E, F & 5A). Body wall scales (0.27–0.48 mm in larger width) with highly projected ridges, mostly on distal portion of polyp, near to the operculum (Figure 5C). Coenenchymal scales 0.35–0.83 mm long (Figure 5D).
REMARKS
Cairns (Reference Cairns2010) considered Callogorgia americana Cairns & Bayer, Reference Cairns and Bayer2002 a junior synonym of Callogorgia gilberti (Nutting, 1908) based on an overlap of characters observed in these two species. Based on the study by Quattrini et al. (Reference Quattrini, Georgian, Byrnes, Stevens, Falco and Cordes2013), we opted for considering C. americana as a separate species.
The molecular mitochondrial markers (cox1 + igr + mtMutS) used by Quattrini et al. (Reference Quattrini, Georgian, Byrnes, Stevens, Falco and Cordes2013) revealed small but consistent differences between these two species, which occupy distinct ocean basins (Cairns, Reference Cairns2010). Furthermore, Quattrini et al. (Reference Quattrini, Georgian, Byrnes, Stevens, Falco and Cordes2013) found ecological niche differences between the Atlantic C. americana (as C. a. americana) (339–384 m, 10.2–12.4°C, 35.3–35.5 salinity) and Callogorgia delta Cairns & Bayer, Reference Cairns and Bayer2002 (as C. a. delta) (403–914 m, 4.3–9.8°C, 34.9–35.1 salinity), showing that it is not ideal to keep them as a single species, as stated by Cairns (Reference Cairns2010).
According to McFadden et al. (Reference McFadden, Benayahu, Pante, Thoma, Nevarez and France2011), although the distinction between species using DNA barcode is more reliable if the divergence is >1%, it is possible to safely distinguish taxons with a <1% divergence if the distinction is well supported by morphology. Quattrini et al. (Reference Quattrini, Georgian, Byrnes, Stevens, Falco and Cordes2013) found a divergence of 0.82% (cox1 + igr1 + mtMutS) between C. gilberti and C. americana (C. a. americana), which when associated to nuclear markers (28S) becomes 1.12%. This result, associated to a biogeographic and ecological context, seems to suggest that C. americana and C. gilberti are in fact two different species, as indicated by Cairns & Bayer (Reference Cairns and Bayer2002).
Quattrini et al. (Reference Quattrini, Georgian, Byrnes, Stevens, Falco and Cordes2013) conclude that C. gilberti, C. americana (C. a. americana) and C. delta (C. a. delta) are different species. Therefore, three nominal species are considered valid: C. gilberti Nutting, 1908, C. americana Cairns & Bayer, Reference Cairns and Bayer2002 and C. delta Cairns & Bayer, Reference Cairns and Bayer2002 (Table 2).
DISTRIBUTION
Straits of Florida, northern Gulf of Mexico, Yucatan Peninsula, Nicholas Channel, Lesser Antilles from Puerto Rico to Tortuga, Venezuela and northern Brazil; 183–732 m.
ACKNOWLEDGEMENTS
The paper was translated and revised by MSc Bárbara de Moura Neves (Memorial University of Newfoundland, Canada).
FINANCIAL SUPPORT
The work was supported by CNPq – Conselho Nacional de Desenvolvimento Científico e Tecnológico (Grant – Edital PROTAX 2010 – 562320/2010-5) and FACEPE – Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco (Grant – APQ-0828-2.04/12).
