Deep-Water Octocorals (Cnidaria, Anthozoa) from the Galápagos and Cocos Islands. Part 1: Suborder Calcaxonia

Abstract Thirteen species of deep-water calcaxonian octocorals belonging to the families Primnoidae, Chrysogorgiidae, and Isididae collected from off the Galápagos and Cocos Islands are described and figured. Seven of these species are described as new; nine of the 13 are not known outside the Galápagos region. Of the four species occurring elsewhere, two also occur in the eastern Pacific, one off Hawaii, and one from off Antarctica. A key to the 22 Indo-Pacific species of Callogorgia is provided to help distinguish those species.


Introduction
Early in my career (1986) I was privileged to participate in a deep-sea submersible expedition to the Galápagos and Cocos Islands, which was sponsored by SeaPharm, Inc. and HBOI (Pomponi et al. 1988). It made rich collections from 27 stations from off the Galápagos (JSL-I-1911(JSL-I- to 1937 and eight stations off the Cocos Islands (JSL-I-1938(JSL-I- to 1945 at depths to 823 m ( Figure 1). Also on board this expedition were research scientists Shirley Pomponi and John Reed. Abundant deep-water invertebrates were collected at all stations, including many corals, but because the goal of the expedition was to seek biologically active compounds from these species, a 25-year sequestration was placed by the National Cancer Institute on all specimens collected. Nonetheless, as a participant in the expedition, I was given permission to publish on the Scleractinia (Cairns 1991a) and Stylasteridae (Cairns 1986(Cairns , 1991b. Now, at the end of my career, I have come full circle to publish on the remaining deep-water corals collected by this expedition. Although the 1986 Johnson-Sea-Link expedition was the first submersible expedition to sample the deep waters off the Galápagos, it was not the first to collect deepwater invertebrates from this region. As early as 1888 the Albatross had made 13 deepwater stations (Alb 2806 to 2819) off these islands, 14 more stations again in 1891 (Alb 3400-3413), and another 10 stations  in 1904, all these specimens being deposited at the NMNH. The Johnson-Sea-Link also made additional collections in the Galápagos in 1995 (JSL-I-3900 to 3985) and in 1998 (JSL-II-3084 to 3113). More recently the E/V Nautilus has made deep-water collections in July 2015. Deepwater octocorals from all of these cruises were examined to form a basis for this report.
Thirteen deep-water octocoral species are reported herein, i.e., those that belong to the suborder Calcaxonia: Primnoidae, Chrysogorgiidae, and Isididae. Approximately an equal number of deep-water octocorals belonging to the families Alcyoniidae, Acanthogorgiidae, Plexauridae and the order Pennatulacea have also been collected from these islands and will be reported in later parts. Of these thirteen species, seven are described as new, four have range extensions, and only two had been previously reported from the Galápagos by Studer (1894).

Material and methods
As explained in the Introduction, this study is based on all the deep-water calcaxonian octocoral specimens collected by the Albatross and John-Sea-Link I and II, which are deposited at the NMNH. It also includes material collected by the Nautilus, which is deposited at the CDRS.
The methodology concerning sclerite preparation for SEM can be found in Cairns (2016). SEM stub numbers are in a series established by the author, and all are deposited at the NMNH. Morphological terminology follows the glossary of Bayer et al. (1983), as updated by Cairns (2012Cairns ( , 2016.
The following abbreviations are used in the text: eter is about 4 mm, including the marginal spines. The polyps are short and cylindrical , only about 1.2-1.4 mm in height, not counting the marginal spines, which can be up to twice as long as the polyp. The actual body wall is relatively short (about 0.5 mm), the opercular scales making up the remaining length of the polyp. The body wall scales  are arranged in eight irregular longitudinal rows, the two distal marginal and submarginal body wall scales being quite different from the lower four or five tiers of scales, the latter (Figure 4f ) being roughly elliptical to rectangular in shape, quite thin, and often having a slightly lobate distal margin. The body wall scales are slightly curved to fit the circumference of the polyp and are highly imbricate. Their outer face is perfectly smooth, their inner face covered with sparse small tubercles. There are eight marginal and usually eight submarginal scales. The marginal scales (Figures 4g, i) have a rectangular to trapezoidal base that is up to 0.6 mm in width, capped by a slender (0.1 mm in diameter basally, but attenuating to a point distally) elongate (up to 2.2 mm in length) spine, the spinose part thus contributing 75-80% of the length of the sclerite. The spine is smooth but itself covered with very small (about 15 µm in length) spines. The submarginal scales ( Figure 4h) may be as large as the marginal scales, but some are only about half as long (0.75-0.90 mm in length, see below). The eight operculars (Figures 4b,e) are arranged in two alternating quartets of four, an inner quartet and an outer, the lateral edges of the outer operculars overlapping those of the inner. The opercular scales are isosceles triangular in shape with a pointed (not spinose) tip, and having a longitudinally concave, perfectly smooth outer surface and a sparsely tuberculate inner surface. They are slightly curved about 45°in order to fold over the polyp to form the operculum. The operculars are 0.7-1.0 mm in height, with a L:W of 1.9-2.6. The marginal and submarginal scales that are aligned with the four inner opercular scales are usually both large in size, whereas the submarginals associated with the outer opercular scales are often much smaller (see above) and may even be absent. The coenenchymal scales (Figure 4j) are irregular in shape but usually elongate, up to 0.65 in greater length. Like most of the other scales, they have a smooth outer surface and a sparsely tubercular inner surface, and are quite thin, and easily broken.
Comparisons. Despite the long distance between the Antarctic type locality and the Galápagos, this specimen is identified as C. carlottae, but it does differ in several points from the original description. The Galápagos specimen has larger polyps, and thus larger opercular and marginal spines, those of the Antarctic syntypes being only 0.6 mm and 0.8 mm in length, respectively. And the Antarctic syntypes have eight or nine polyps per whorl, whereas the Galápagos specimen has only six or seven. Otherwise, the two specimens are remarkably similar, the Galápagos specimen even showing the dimorphic-sized submarginal spines (Kükenthal 1912: fig. 43). The specimens reported by Bayer as C. carlottae are not considered conspecific, based on a difference in the size and number of rows of submarginal spines (see Cairns 2016), as well as having differently shaped marginal spines and thicker granular body wall scales.
Remarks. This is the first report of this species subsequent to its original description, and was collected at virtually the same depth. Description. Colonies are uniplanar and taller than broad, the holotype ( Figure  2a) measuring 49 cm in height and 18 cm in width, with a broken basal branch diameter of 5.9 mm. Another colony fragment (JSL-I-1915) has a broken basal branch diameter of 8.9 mm, suggesting a colony height of close to 1 m. Branching is alternate pinnate (sympodial and geniculate), the terminal branchlets up to 13 cm in length. The polyps are arranged in whorls of five or six ( Figure 5a); four to five whorls occur per cm branch length; the whorl diameter ranges from 2.5-3.1 mm. The polyps are 1.5-2.0 mm in length, slightly curved, and clavate (Figure 5b-d). The color of the colony and polyps is white.
There are eight longitudinal rows of body wall scales, decreasing in number from ab-to adaxial polyp side, the body wall sclerite formula being: 10-12:10-12:4-5:2. The distal five or six pairs of abaxial scales (Figure 5f ) are narrow (0.31-0.35 mm     (Figure 5c). At the junction of the lowest body wall scales and the branch coenenchymal sclerites is a pair of crescentric infrabasal scales (Figure 5j) that forms a transition, each about 0.6 mm wide and 0.25 mm in height. The distalmost body wall scales in each row fold over the operculum as a short circumoperculum (Figure 5c). The opercular scales (Figure 5e) range in length from 0.50-0.65 mm, decreasing in length from ab-to adaxial polyp side, forming a prominent operculum; their L:W ranges from 1.7-2.25. Their outer surface is covered with tall serrate ridges and their edges are finely serrate. Their inner face is tuberculate, the distal third bearing a multiply serrated keel. The coenenchymal sclerites ( Figure 5k) are elongate (L:W = 5-6), thick sclerites, arranged parallel to the branch axis, measuring up to 0.8 mm in length and 0.13-0.14 m in width. Their outer surface is coarsely granular.
Comparisons. Callogorgia galapagensis belongs to a group of eight species that have highly cristate abaxial body wall scales, the other seven species listed in Cairns (2016), the Pacific component indicated in the key above by asterisks. The prominent ridges on these body wall scales often make it difficult to see the boundaries between adjacent rows of body wall scales. Callogorgia galapagensis can be distinguished from the other seven species by its sclerite formula, being the only species to have 10-12 abaxial and outer lateral body wall scales. This character is not used in the key above, and thus C. galapagensis keys closest to C. sertosa and C. tessellata, but can be distinguished by its unique sclerite formula.
Etymology. Named for the type locality of the species.
Callogorgia kinoshitai (Kükenthal, 1913 Types. Kükenthal (1913) established this species on the specimens described by Nutting (1909) as C. sertosa. Although Kükenthal examined some of those specimens and added information about them, he did not report any additional specimens or designate a type. The specimens reported by Nutting (1909) are thus considered as syntypes, and include those from Alb-4356, Alb-4357 (USNM 30084, SEM stubs 2298-2299), Alb-4358, all presumably deposited at the NMNH, although only Alb-4357 could be located in 2017. Type locality. As defined by the syntype series, the type-locality extends from northern Baja California (latitude 30°30'30"N) to just north of San Diego (latitude 33°02'15"N), and includes the bathymetric range of 219-2469 m. Description. Colonies are uniplanar and taller than wide, the largest Galápagos specimen (Alb-3406) a broken colony only 18 cm in height, but the largest syntype measuring up to 26 cm in height. Branching is alternate pinnate (sympodial and geniculate, Figure 2b), the terminal distal branchlets only about 4 cm in length. The polyps are arranged in whorls of two or three (Figures 6a, b), although Kükenthal (1919) reported a range of two to six, with four being the most common number. The whorl diameter is about 1.5 mm. The polyps are 1.3-1.5 mm in length, and slightly clavate (Figures 6c, d). The color of the colony and polyps is white.
There are eight longitudinal rows of body wall scales, decreasing in number from ab-to adaxial polyp side, the body wall sclerite formula being: 6-8:1-2:1-2:1-2. The marginal and submarginal abaxial body wall scales ( Figure 6g) have a ctenate distal edge and increase in width and thickness from distal to proximal position. The basalmost abaxials are short but quite wide (up to 0.95 mm), curving around most of the basal part of the polyp and occupying the space normally reserved for the proximal outer and inner lateral scales. These scales serve as infrabasals (Figure 6i), forming a transition from the plate-like body wall scales ( Figure 6h) to the thick elongate coenenchymal scales (Figure 6j). The outer ( Figure 6f ) and inner lateral body wall scales are quite wide (0.5-0.6 mm) and have a finely serrate distal edge. The adaxial scales ( Figure 6d) are narrow, only about 0.3 mm in width. The outer surface of the body wall scales is relatively smooth, and covered with small, low granules. All body wall scales are curved to fit the circumference of the polyp body. The opercular scales ( Figure  6d, e) range in length from 0.50-0.75 mm, decreasing in length from ab-to adaxial polyp side, forming a prominent operculum; their L:W ranges from 2.8-3.0. The relatively high L:W ratio is caused by an attenuate tip that is essentially round in cross section and covered on all surfaces by small spines arranged in longitudinal rows. The coenenchymal sclerites ( Figure 6j) are elongate (L:W = 5-6) and thick, up to 0.55 mm in length and about 0.1 mm in width. They are longitudinally arranged in one layer on the branches. Their outer surface covered by low granules.
Comparisons. Although this species was originally identified as C. sertosa by Nutting (1909), that species differs in having more pairs of outer body wall scales, a pitted body wall outer surface texture, and a tessellate coenenchymal scale arrangement (Cairns 2016). As seen from the key above, C. kinoshitai is most similar to C. joubini (Versluys, 1906) (Indonesia, 520 m deep) but differs from that species in having inner and outer lateral scales and elongate (not polygonal) coenenchymal scales.
Nomenclature. This species was clearly named after Kumao Kinoshita, and thus the name is herein changed to reflect a masculine ending.
Type species. Calyptrophora japonica Gray, 1866, by monotypy. Diagnosis. Colonies uniplanar to slightly bushy (lyrate, dichotomous, polychotomous, biplanar) or unbranched. Polyps arranged in whorls, the polyps facing either upward or downward. Polyps consist of two annular sclerite rings, each composed of two inseparably fused scales; a pair of crescent-shaped infrabasals also present. Articular ridge present between basal and buccal body wall scale. Distal margins of body wall scales often spinose, toothed, or lobate. Operculum composed of eight scales; keels usually present on inner face of opercular scales. Coenenchymal scales elongate and flat, sometimes quite thick (as plates). Small curved tentacular platelets often present.
Distribution. Tropical and temperate latitudes of Atlantic, Pacific, and Indian Oceans, 227-3531 m deep.
Remarks. Including the new species described herein, the genus contains 23 species, making it the fifth most species-rich genus within the primnoids. Bayer (2001) divided the genus into two species complexes, one having their polyps directed upward, the other having their polyps directed downward. Although helpful in grouping and identifying species, these two species groups do not seem to have phylogenetic validity (Cairns 2009, Cairns and Wirshing in review).
The fused basal scale (Figures 7d-f ) stands perpendicular to the branch and is up to 2.1 mm in height, the distalmost 0.9-1.1 mm consisting of two elongate spines (Figure 7 d,  ) range in length from 0.45-0.90 mm, decreasing in length from ab-to adaxial polyp side, forming a relatively small operculum that is encircled by the buccal cowl; their L:W ranges from 1.9-3.3. The operculars are thin, flat, and triangular, with a blunt apex; their outer surface is smooth to slightly granular, their inner surface covered by a longitudinal keel. The coenenchymal scales ( Figure 7j) are thin, flat, and elongate, with blunt ends, and up to 0.8 mm in length. Their outer surface is covered with small, low granules.
Comparisons. Only four of the 23 species of Calyptrophora have polyps oriented in the downward direction (Cairns 2009). Calyptrophora agassizii easily differentiated from the others by having equal, dichotomous branching and keeled opercular scales.
Remarks. Several monographers have redescribed this species, but apparently based only on the type material. This is the first subsequent report of the species based on new material. The latitude reported by Studer (1894) for the type specimens is incorrect, it being 1°03'S, not north latitude.  Description. The colony is uniplanar, equally and sparsely dichotomously branched, some end branches up to 12 cm in length. The holotype (Figure 2d) is only 6.6 cm in height, whereas the paratype from JSL-I-1922 is larger (20 cm) but poorly preserved. Polyps are directed downward, and occur in whorls of four to six (Figure 8a), the whorl diameter measuring 4.0-5.5 mm; the whorls are closely spaced, about four polyps occurring per cm branch length. The horizontal length of a polyp is 2.2-2.4 mm. The axis is dark brown to bronze color.
The fused basal scale (Figures 8a, d, e) stands at roughly a 45° angle to the branch, and is 2.0-2.3 mm in height, including its distal spines. The distal spines (Figure 8d, f,) are flattened, with a broad base 0.30-0.35 mm in width, and extend 0.45-0.55 mm above the articulating ridge. Both inner and outer surfaces of the basal spines are covered with 6-11 thin, parallel spinose ridges. The straight articulating ridge is well defined (Figure 8d, f, g)  Comparisons. Only four species in the genus have downward oriented polyps, the so called wyvillei-complex sensu Bayer (2001), C. reedi being very similar to C. agassizii, also known from the Galápagos. Calyptrophora reedi differs from that species primarily in the shape of its basal scales, which are not as long as those of C. agassizii, have a broader base, and a non-pointed (flat) tip.
Etymology. Named in honor of John Reed (HBOI), who participated in the JSL-I Galápagos expedition of 1986, during which this species was collected. Each polyp covered with three (rarely four) pairs of abaxial body wall scales, one pair of basals, one or two pairs of medials, one pair of buccals, and one to four pairs of small adaxial scales, nevertheless leaving the adaxial side largely naked. Articular ridge present between basal and medial body wall scale. Distal margins of body wall scales often spinose, toothed, or lobate, often extending as a protective cowl. Opercular scale usually keeled. Coenenchymal scales often quite thick, of variable shape, sometimes ridged (i.e., "sail-scales"). Tentacular platelets often present.

Genus
Distribution. All ocean basins except Arctic, 128-4594 m deep. Remarks. Previously (Cairns 2012) I stated that there were 43 valid species of Narella, but I inadvertently counted two junior synonyms within this tabulation, so, in fact, there are only 41 valid species. The new species described herein brings the total to 42. A unified key to all species known after 1924 (Kükenthal 1924) does not exist, but regional keys are available for 29 of these species: the seven western Atlantic species (Cairns and Bayer 2003), the nine Hawaiian species (Cairns and Bayer 2007b), the five Alaskan species (Cairns and Baco 2007), and the eight New Zealand species (Cairns 2012 Types. As mentioned in the account of Calyptrophora agassizii, about 65% of the type lot (branches and detached polyps) of that species consisted of Narella ambigua. Narella ambigua was collected at the previous station (Alb-3403) to that of C. agassizii (Alb-3404), approximately 20 km to the northeast and bathymetrically 2 m shallower, both stations from off the southern coast of San Cristóbal. The Narella specimens were separated from the type lot of C. agassizii in 2008 and cataloged as MCZ 79048. Since the type of S. ambigua could not be found at the MCZ in 2008, the specimens cataloged as MCZ 79048 may serve as representative topotypic specimens, and may in fact be type material. A fragment of this colony is also deposited at the NMNH (USNM 1405230). Description. The colony is uniplanar, and dichotomously (laterally) and sparsely branched (Figure 2e), large colonies being up to 28 cm in height and up to 1 cm in basal branch diameter. Terminal branches may be quite long, up to 15 cm. The axis is pale yellow. The polyps are arranged in whorls of five to seven (Figure 9e); whorls are not directly adjacent to one another and thus there are only approximately 2.5 whorls per cm branch length; the whorl diameter of terminal branchlets is about 6-7 mm. The horizontal length of a polyp is 2.5-3.0 mm.
The basal scales (Figure 9c, f) stand perpendicular to the branch and extend up to 2.8 mm in height, the distal 0.6-0.7 mm portion projecting beyond the junction with the medial scales as a broad lobate extension (Figure 9b). The lateral edge of one of the basal scales of a polyp will often enlarge and curve toward the corresponding enlarged basal scale of the adjacent polyp, forming a solid tube up to 3.5 mm in diameter that houses a commensal polychaete worm (Figure 9e). The dorso-and anterolateral faces of the basal scales are gently curved, not ridged. The medial scales ( Figure 9g) are narrow, 0.9-1.1 mm in length, and have upturned edges proximally and distally (saddle-shaped). The buccal scales (Figure 9b, c, h) are longer (up to 1.6 mm) and about twice as wide as the medials, their distal edges rounded and smooth, forming a cowl (Figure 9a) up to 0.6 mm that encircles the operculum; the distal edges of the two buccal scales form a bilobate shape for the tip of each polyp, not unlike the distal edges of the basal scales. The ratio of the major body wall scales is about: 1:0.6:0.7. There are four pairs of small elliptical adaxial body wall scales (Figure 9d, j), ranging from 0.26 to 0.42 mm in greater diameter. The outer faces of all body wall scales are covered with small granules and thus look rather smooth. All of the opercular scales (Figure 9i) are roughly the same length, ranging from 1.0-1.3 mm in length, but the single abaxial opercular is quite broad (e.g., L:W = 1.2), whereas the single adaxial is quite slender (e.g., L:W = 3.0). The other six lateral operculars usually have a basal shoulder on their adaxial edges and thus have an intermediate L:W ratio. The outer surface of the operculars is granular like the body wall scales, whereas the inner surface bears a rounded keel. The coenenchymal scales (Figure 9k) are irregular to polygonal in shape, up to 1.4 mm in length, and have a flat to slightly concave outer surface.
Comparisons. Narella ambigua is easily distinguished from the somewhat similar Paracalyptrophora enigma by its long terminal branches, polychaete commensalism that causes highly modified basal scales, fewer polyp whorls per cm, non-toothed basal scales, lack of an articular ridge, and granular (not ridged) coenenchymal scales.
Remarks. Although discussed by several authors through the years (see synonymy), this is the first subsequent report of this species since its original description.
Diagnosis. Colonies dichotomously branched in one plane, sometimes in a lyrate pattern and sometimes as two parallel fans. Polyps arranged in whorls of up to eight, all polyps pointed downward. Each polyp covered with two (rarely three) unfused pairs of body wall scales. Articluar ridge present between basal and buccal (or medial) body wall scales. Distal margins of buccal scales smooth or spinose. A pair of infrabasal scales often present. Coenenchymal scales elongate, granular, and sometimes ridged.
Remarks. The genus diagnosis is herein expanded to accommodate a species having three pairs of body wall scales, otherwise similar to the genus Narella. The character placing it in Paracalyptrophora is its possession of an articular ridge, which is found in this genus as well as Calyptrophora, and is considered more significant than the number of body wall scales. Description. The colony is uniplanar, equally and dichotomously branched, the largest colony (the holotype, Figure 3a) being 17 cm in length and having only 12 terminal branches, none longer than 4 cm. Its broken base is highly calcified and 10.5 mm in diameter. The entire corallum is white. The polyps are arranged in closely spaced (4.5-5 polyps per cm) whorls of seven or eight (Figure 10a), the higher number occurring on larger-diameter basal branches; the whorl diameter ranges from 4.5-6.0 mm. The horizontal length of a polyp is 2.5-2.7 mm.
The basal scales (Figures 10a, e) stand perpendicular to the branch or tilted slightly anteriorly, and extend up to 1.75 mm in length, the distal 0.23-0.28 mm of each basal scale projecting as wide, flat teeth, which are longitudinally ridged on their inner surface (Figure 10d). There is a horizontal articular ridge joining the basal to the medial scales ( Figure 10d). Otherwise, the inner surface of the basal scale is highly tuberculate, and its outer surface is smooth and not ridged, as are all the body wall scales. The medial scales (Figure 10f) are as wide as the buccals, 1.10-1.15 mm in length; the distal and lateral 0.25 mm of their inner surface is smooth (but not ridged), the rest highly tuberculate. The buccal scales (Figure 10g) are slightly longer (1.12-1.25 mm) but much wider, curved around much of the operculum in a scalloped shape. The 0.5 mm distal, inner margins of these scales are also smooth and thin, forming a translucent cowl (Figure 10c) surrounding the operculum. The ratio of the major body wall scales is about: 1:0.67:0.77. There is at least one pair of rectangular adaxial scales (Figure 10c), each about 0.37 mm in width. The single abaxial opercular scale (Figure 10h, leftmost) is 0.85-0.90 mm in length and has two broad lateral lobes (producing a very low L:W of 0.75-0.85) and thus being symmetrical, and has a small rectangular base. The much smaller, symmetrical, paired adaxial operculars are 0.75-0.80 mm in length with a L:W of about 2.0. The five lateral operculars range in size from 0.90 to 1.05 mm in length and are asymmetrical, each having a lobe on their adaxial side, the L:W ranging from 1.5-1.6 ( Figure 10h). The distal inner half of all oper-cular scales bears a thin ridged keel, whereas the outer surface is covered with low pointed granules. The coenenchymal scales (Figure 10i, j) are elongate (L:W up to 8) and longitudinally crested (i.e., "sail scales", Figure 10j), the crests up to 0.15 mm in height. The outer surface of these scales is covered with small granules much like that of the operculars.
Comparisons. Superficially this species resembles the genus Narella, in that it has three pairs of body wall scales, but the distal inner surface of the basal scales have an articular ridge, which is more consistent with the genus Paracalyptrophora, P. enigma being the only species in the genus with three pairs of body wall scales.
Etymology. Named "enigma" (Latin for inexplicable) because it is the only species in the genus to have three (not two) pairs of body wall scales.
Type species. Gorgonia penna Lamarck, 1815, by subsequent designation (Wright and Studer 1889). Diagnosis. Colonies usually uniplanar and alternately pinnately branched, dichotomously branched, or bottlebrush in shape. Polyps arranged in alternate biserial fashion (nominate subgenus), crowded on all sides (subgenus Dicholaphis), paired (subgenus Faxiella), or arranged in whorls (subgenus Verticillata). Each polyp covered by eight rows of body wall scales, the adaxial scales usually somewhat smaller. Distal edges of marginal body wall scales do not overlap much of opercular scales. Inner surface of opercular scales may be smooth or ridged, but not keeled, except in subgenus Faxiella.
The body wall scales (Figure 11e) are arranged in eight somewhat irregular longitudinal rows, the sclerite formula being: 5-6:4-5:4-5: variable. All marginal scales, except for the abaxial marginals, are roughly rectangular, 0.35-0.64 mm in width, and have a straight distal margin that covers only a small proximal part of the opercular scales. The distal edges of the two marginal scales project as small teeth. All body wall scales except for the adaxials become progressively larger and transform to triangular toward the base of the polyp. The adaxial body wall scales (Figure 11a, g) are small (0.25-0.35 mm in diameter) and random (variable) in arrangement, but cover the entire adaxial side of the polyp. The body wall scales are relatively thick, convex, and covered with low ridges; their distal edges are finely serrate. The opercular scales (Figure 11f ) are triangular in shape (0.75-1.2 mm in length, L:W = 2.2-2.9), each with an elongate distal process, the length and L:W progressively decreasing from ab-to adaxial side; the operculum is quite prominent (Figure 11a-c). The outer opercular face is covered with granules basally and short serrate ridges distally; the inner face is also covered with serrate ridges raised into a keel-like structure distally, but having tubercles proximally. The coenenchymal scales (Figure 11h) are elongate (L:W about 4), with a granular outer surface and a tuberculate inner surface.
Comparisons. This is the deepest of the 37 known species in the genus. Only one other species occurs in this subgenus, P. (F.) delicatula (Thompson and Rennet, 1931), known only from the New Zealand region at 650-2743 m depth (Cairns 2016). These species are compared by Cairns (2016).
Remarks. The specimens reported herein are only the second report of the species. It fits the re-description of the holotype given by Zapata-Guardiola and López-González (2012), except that the Galápagos specimen sometimes has polyps arranged in whorls of three.

Diagnosis.
Colonies uniplanar to slightly bushy; branching lateral and somewhat irregular. Polyps stand perpendicular to branch, arranged independently or in pairs or whorls of up to four. Eight marginal scales present, offset in position from opercular scales; marginal, and sometimes submarginal, scales fluted; nematocyst pads present on distal inner surface of fluted marginals. Body wall scales arranged in four to eight longitudinal rows. Operculum well developed, the distal inner surface of operculars prominently keeled. Coenenchymal scales flat to highly concave, sometimes ridged. Pinnular rodlets sometimes present.
Distribution. Cosmopolitan, except for eastern Atlantic, the Arctic, and off continental Antarctica, 475-3470 m depth.
Remarks. Including the new species described herein, there are eight species known in this distinctive genus. Accounts of Parastenella species are found in Cairns (2007bCairns ( , 2010Cairns ( , 2016 and Cairns and Bayer (2009). Description. The colony is uniplanar, the largest colony (the holotype, Figure 3c) measuring 44 cm in height, and having a basal branch diameter of 6.5 mm. Branching is lateral and somewhat irregular; the longest terminal branchlets are less than 2 cm in length. The axis is golden bronze and the polyps and coenenchyme are white. The polyps are 2.8-3.1 mm in height and stand perpendicular to the branches, arranged in pairs (Figures 12a, b), whorls of three, and often as singles; about five polyp whorls (or pairs) occur per cm branch length.
The body wall scales (Figure 12d) are arranged in eight rows, each row with six scales, the lateral edges of all scales overlapping with those of adjacent rows. The eight marginal scales form an asymmetrical rosette: six of the marginals consist of elongate scales (up to 0.9 mm in length and 0.4 mm wide) with broad shallow flutes, whereas the two adaxial marginals are much wider but shorter (up to 0.6 in length and 0.9 mm in width) and are flat (without a flute) or bear only a very shallow flute (Figure 11c). A nematocyst pad (Figure 12c  adaxial operculars are symmetrical, the abaxial having two lateral lobes (H:W about 1.2), the adaxials lacking lobes (H:W about 2); the lateral operculars are asymmetrical, each having only one lobe on the adaxial lateral side. All opercular scales have a deeply longitudinally creased outer surface that corresponds to a sharply keeled inner surface.
The coenenchymal scales (Figure 12g) are irregular in shape, although usually longer than broad, and up to 1.1 mm in length. Their outer surface is concave, like that of the body wall scales, and bears low granules and occasionally short ridges.
Comparisons. Parastenella pomponiae is morphologically most similar to P. ramosa (Studer, 1894), known from the eastern Pacific from the Gulf of Alaska to Panama, but differs from that species in having eight (not five) rows of body wall scales, concave (not flat) coenenchymal scales, wider fluted marginal scales, and in lacking submarginal fluted body wall scales.
Etymology. Named in honor of Shirley Pomponi (formerly of HBOI), who participated in the JSL-I expedition of 1986, during which this species was collected.

Genus Chrysogorgia Duchassaing and Michelotti, 1864
Chrysogorgia Duchassaing and Michelotti 1864: 13;Versluys 1902: 17-33;Kükenthal 1919: 505-511 Duchassaing and Michelotti, 1864, by monotypy. Diagnosis. Branching from main branch sympodial in an ascending spiral, clockwise (R) or counterclockwise (L), usually following a repeated geometric branching formula, producing a bottlebrush colony, or dichotomous in one or more parallel planes. Branchlets repeatedly dichotomously branched, resulting in short terminal segments. Polyps large in relation to branchlets, standing perpendicular to branchlets and usually well separated. Sclerites consist of rods and scales. Axis with a brilliant metallic luster, usually golden or yellow in color, and thus referred to as the golden corals.
Remarks. In order to manage the relatively large number of species in the genus, now standing at 70, Versluys (1902) divided the genus into three group based on the presence of rods or scales in the body wall and tentacles of each species, which he referred to as Groups A-C. Table 1 is a graphic representation of the four permutations of these two characters as divided between the two regions of the polyp. This table also lists the number of species currently assigned to each group, their geographic and depth ranges, and the branching formulas encountered within the group. A species having the fourth permutation, Group D, was not reported until 2015 (Cordeiro et al. 2015). Recent molecular evidence (Pante et al. 2012), based on three genes, supports the monophyly of the genus as well as groups B and C, but results in Group A being paraphyletic. Regardless of the true phylogeny of the species, the grouping of Versluys (1902), along with the branching formula, served to help distinguish the various species. Description. The colony is biplanar (perhaps multiplanar), the largest colony examined (JSL-I-1927, Figure 3d) being 25 cm in height and 10 cm in width, and is somewhat bushy. The branching is dichotomous, the length of the internodes 6-7 mm, each internode bearing only one or sometimes two polyps. The polyps are 2.3-2.8 mm in height and project perpendicular to the branches (Figure 13a-c), having a relatively narrow body wall column and a much larger distal crown, made larger by the projecting sclerites that support the tentacles. The axis is a metallic bronze in color.
The body wall scales (Figure 13c, d) are transversely arranged and slightly curved to fit the circumference of the polyp. The body wall scales, called "slippers" by Bayer and Stefani (1988), are up to 0.65 mm in length and 0.07-0.10 mm in width, resulting a L:W ratio ranging from 4.5-6.0; these scales are quite thin (about 0.03 mm). Some body wall scales are often slightly irregular in shape but usually rounded on their distal ends; their inner and outer faces are smooth and their edges rounded. The tentacular scales (Figure 13e) are similar in shape to the body wall scales but somewhat smaller, i.e., 0.35-0.45 mm in length. The base of each tentacle bears a distinctive tear-dropped shaped region about 0.4 mm long and 0.18 mm in width that is devoid of sclerites (Figures 13a-c). These regions are surrounded by flattened scales that project around the lower edge of the tentacle and thus forming a support for it. These scales sometimes have a root-like or lobate base (Figure 13f ). The pinnular scales (Figure 13g) are 0.20-0.25 mm in length and are similar to the body wall scales, except that they have slightly serrate marginal edges. The coenenchymal scales ( Figure 13c) are indistinguishable from the body wall scales, and are arranged longitudinally parallel to the branch axis.
Comparisons. Chrysogorgia scintillans belongs to "Group C" sensu Versluys (1902) ( Table 1), i.e., species having sclerites in the form of scales in both tentacles and body wall. Currently there are 18 species known in this grouping (Cairns 2001;Pante and Watling 2011), three of which, including C. scintillans, having flabellate or multiflabellate colonies and non-spiral branching. As noted by Bayer and Stefani (1988: key), C. scintillans is most similar to C. electra Bayer and Stefani, 1988, another flabellate species, but differs in having larger polyps, smaller projections beneath the tentacle bases, and slightly different shaped to their body wall and coenenchymal scales. Description. The colony is bottlebrush in shape (Figure 3e), the holotype measuring 26 cm tall and 12-13 cm in maximum diameter, having a basal branch diameter of 2.5 mm. The branching is sympodial, the branching formula being consistently 1/3L. The orthostiche interval is 12-18 mm. The length of the internodes of the branchlets ranges from 4.0-5.9 mm, up to nine nodes occurring on each branchlet; each internode supports one polyp. The polyps are about 1.1 mm in length, cylindrical (Figures 14a, b), and when preserved in alcohol tend to curve toward the branch surface, the tentacles often adhering to the surface branch. The axis is bronze in color.
The body wall sclerites (Figure 14a-c) are slightly flattened, rotund rods 0.22-0.25 mm in length, having a L:W of 5-6. They are straight and longitudinally oriented. The tentacular sclerites (Figure 14d) are similarly shaped rods, but are slightly shorter (0.18-0.22 mm in length) and more elongate (L:W = 5-8), also longitudinally oriented along the tentacles. All of the rods bear low sparse granulation. The pinnular scales ( Figure  14e) are 0.08-0.12 mm in length, about 0.005 mm in thickness, and have a L:W of 3.5-4.5. The coenenchymal scales (Figures 14a, f ) are 0.13-0.17 mm in length, about 0.01 mm in thickness, and have a H:W of 3.5-5.0. They are longitudinally oriented along the branch axis.
Comparisons. Having rods in its body wall and tentacles places C. midas in Chrysogorgia Group A, the largest of the four groups of Chrysogorgia, consisting of 38 species (Table 1). C. midas is the only species in this group to have a 1/3L branching formula, this formula being much more common in Group C and in one species of Group B (see Cairns 2001).
Etymology. Named "midas" (from the Greek Midas, the mythical king at whose touch everything turned to gold) in allusion to the golden luster of the branch axis, characteristic of the genus.  Description. The colony is bottlebrush in shape (Figure 3f ), the holotype 11 cm tall and 6 cm in maximum diameter, having a basal branch diameter of 2.3 mm.
Branching is sympodial, the branching formula being consistently 2/5L. The orthostiche interval varies from 10 to 23 mm, the shorter intervals near the base of the colony, the higher intervals near the top. The length of the internodes on the branchlets is 3-5 mm, up to five or six nodes occurring on each branchlet; each internode supports two polyps. The polyps are 1.5-1.9 mm in length and cylindrical in shape, with a slightly swollen base (Figure 15a). The axis is metallic gold in color tinged with a greenish hue.
The upper body wall sclerites (Figure 15c), those associated with the cylindrical part of the polyp, consist of slightly flattened rotund rods that are 0.19-0.24 mm in length and having a L:W of 3.5-4.7. They are straight, longitudinally oriented, and uniformly covered with very small granules. Distal to the body wall are the tentacles, which may compose as much as half of the polyp length. They are also composed of slightly flattened rods (Figure 15c), but these rods are longer and more slender, 0.25-0.32 mm in length, with a L:W of 5.1-9.0. Like the upper body wall rods, they are straight and similarly granulated. The pinnular scales (Figure 15f ) are smaller (0.073-0.16 mm in length) curved platelets, having a L:W of 3.4-4.5. The swollen base of the polyp is covered with flattened rods similar in shape to those of the tentacles (Figure 15d), as well as waisted scales 0.17-0.21 mm in length and having a L:W of 2.4-3.4. Otherwise, the coenenchyme seems to be devoid of sclerites.
Comparisons. Having rods in its body wall and tentacles places C. laevorsa in Chrysogorgia Group A, the largest of the four groups of Chrysogorgia, having 38 species. Chrysogorgia laevorsa is the only species in this group to have a 2/5L branching formula, whereas 14 species in this group have a 2/5 R formula (Figure 15b). The 2/5L formula is found in only four species of Chrysogorgia, all belonging to Group C.
Etymology. Named laevorsa (from the Latin laevorsus, meaning "towards the left") in allusion to the direction of the branching formula (2/5L). Diagnosis. Colonies sparsely branched, dichotomously or trichotomously from nodes, resulting in a uniplanar colony; internodes long and hollow. Polyps non-retractile, cylindrical, armed with stout needles placed longitudinally in body wall. Spiny pharyngeal rodlets present.
Remarks. Including the species described below, there are currently six species in the genus, three of which occur in the Pacific. The genus was most recently keyed and discussed by Bayer (1990).
Using one or two mitochondrial genes and six species (most of them undescribed), France (2007) and Dueñas et al. (2014: Figure 2) indicated that Isidella was not monophyletic. Both papers imply that branching pattern, which has traditionally been used to distinguish keratoisidinine genera, is not a reliable character. Description. The colony is uniplanar, the largest specimen (the holotype, Figure  3g) measuring 18 cm in height and 7 cm in width, with a basal branch diameter of 1.7 mm. The holotype shares a thin basal encrustation with another specimen (a paratype). Branching is always dichotomous from nodes, the internodes ranging from 9-14 mm in length. The internodes are white, not longitudinally grooved, and hollow, the central canal (Figure 16b) constituting about 35-40% of the branch diameter.

Isidella tenuis
The polyps are uniserially placed (Figure 16a), their bases about 4-6 mm apart, but because of the length of the upturned polyps there is only 1-3 mm between adjacent polyps. The polyps are cylindrical and slender (Figure 16a), up to 3.3 mm in length and about 0.5 mm in diameter. Most of each polyp consists of eight elongate (up to 2.9 mm, L:W = 26-31), straight, cylindrical needles (Figure 16d), their pointed tips projecting beyond the tentacles. The sclerites bear numerous short (22-26 µm in length) ridges about 5 µm in height, which are arranged longitudinally on the sclerite (Figure 16e). Toward the base of the polyp are several shorter needles 0.95-1.0 mm in length (L:W = 17-19), these needles (Figure 16f ) also being cylindrical but having blunt, flattened tips. Directly adjacent to the coenenchyme are also several even shorter needles (0.5 mm in length, L:W = about 13), also with flattened, blunt tips ( Figure 16i). These two smaller size classes of needles allow for some flexibility of the polyp where it attached to the branch. The tentacular platelets (Figure 16h) are numerous, consisting of flat, blunt-tipped sclerites 0.095-0.1 mm in length and having a L:W of about 7. Their flat surfaces are fairly smooth, covered by small granules and Comparisons. Isidella tenuis differs from I. trichotoma Bayer, 1990(Hawaii, 1920 in having dichotomous branching, much smaller coenenchymal and body wall sclerites, and differently shaped pharyngeal sclerites. Isidella tenuis differs from I. tentaculatum Etnoyer, 2008(California to Alaska, 720-1050 in having needleshaped body wall scales, differently shaped pharyngeal scales, smaller polyps, uniserial polyps, and blunt-tipped body wall sclerites. Etymology. Named "tenuis" (Latin for thin) in reference to the slender polyps of the species.