Keratoisis Wright, 1869

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 : 260-264

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Keratoisis Wright, 1869


Genus Keratoisis Wright, 1869 Figures 41A, B View Figure 41 , 42 A–C View Figure 42 , 43 A–E View Figure 43

Ceratoisis Wright, 1868: II, p. 427 (name only). Verrill 1883: 10. Wright and Studer 1889: 26. Hickson 1907: 5. Nutting 1908: 570.

Keratoisis Wright, 1869: III, p. 23, 24. Gray 1870: 18. Studer 1878: 662. Wright [and Studer], 1889: xlii-xliii, 25, 26. Thomson and Henderson 1906b: 429. Nutting 1910b: 9. Kükenthal 1915a: 117, 120, 121. Molander 1929: 78. Grant 1976: 30.

(= Bathygorgia Wright & Studer, 1889: 691; Cairns and Bayer 2005, listing only).

Type species.

Keratoisis grayi (Wright, 1869). Some few years ago, UNESCO-IOC Register of Marine Organisms proposed the possibility of Keratoisis ornata Verrill, 1878 being a synonym of the type. Information provided on World Register of Marine Species (WoRMS) indicated that that synonymy is now accepted (Cordeiro et al. 2019).

Type locality.

Specific locality of type unknown; generally, bathyal, from NE to NW Atlantic Ocean; also Mediterranean Sea.

Type specimen(s).

Location of the type species could not be determined.

Material examined.

~3 lots (see Appendix 3: List of material examined.)


Colonies ( Figure 41A View Figure 41 ) branched (few and distant, ~5.0 cm from one branch to next), with branches arising at nearly 90° angle, on same side, or opposite(?); near a node or from middle to end of long (4.0-5.0 cm), calcareous internode, then slightly curving; no secondary branching; some unbranched; generally uniplanar. Base can be either root-like calcareous structure for anchoring into soft substrate or a basal disc for attachment to a hard substrate. Axis as seen in the family; internodes calcareous, white, not composed of fused sclerites, hollow (often) or solid; and purely proteinaceous, horny, shorter (2.0 mm tall), reddish-brown to dark brown nodes, alternating with internodes. Overall color of colony (preserved) creamy yellowish; coenenchyme translucent yellow. Polyps ( Figure 41B View Figure 41 ) cylindrical, height between 4.0-8.0 mm; not retractile. Polyps irregularly arranged, but with tendency toward biserial arrangement; in general, somewhat curved, distal part of polyp body with eight longitudinal rows of spindles and needles, some projecting beyond tentacles. Tentacles of polyp form a rounded top, like a mushroom, with individual tentacles usually visible. Distance between polyps no more than 1.0 cm but usually less. Coenenchyme very thin, transparent; straw-yellow in specimens examined. Sclerites ( Figure 42 A–C View Figure 42 , 43 A–E View Figure 43 ) generally long, fusiform spindles; some ( Figure 43B View Figure 43 ) very long (needles) and others ( Figure 43A, C–E View Figure 43 ) more numerous, of moderate length, in coenenchyme and polyp bodies; those in coenenchyme not always obvious; polyps armed with eight-plus, needle-like sclerites (largest), often (not always) projecting beyond tentacles as sharp marginal spines between bases of tentacles, coming from eight longitudinal rows of spindles and needles. Sclerite surfaces seemingly smooth, or (if present) with dense low warts, in parallel. Stellate forms seen in pharynx. Sclerites colorless to light tan, depending on species.


No clear derivation for this genus name was found. All members of this genus are referred to as species of Bamboo coral. Genus Keratoisis is accepted; WoRMS Database (Cordeiro et al. 2019) shows the spelling variation, Ceratoisis Verrill, 1883, as synonymized with Keratosis Wright, 1869.


It had been noted (Verrill, 1922) that this genus included some of the largest known species of the family; specimens of K. ornata (now K. grayi ), from considerable depth, on the banks off Newfoundland and Nova Scotia, can be ~ four feet high. As well, this genus is composed of species that may live to considerable age. Andrews et al. (2005) stated that age for some of these coral colonies may exceed 200 years.


Discussion of the genus included here, as several fragmented specimens in the collection of SIO and NMNH were collected off California (see Appendix 3: List of material examined and discussion in this section). The speculation is that this genus may be seen throughout much of the Pacific Ocean, at depth, based on collection location data found via on-line databases, etc. Several species that might be of interest with regards to the California Bight could include K. paucispinosa (Wright & Studer, 1889) ranging from Alaska to Hawaii, K. philippinensis (Wright & Studer, 1889), which is generally a western Pacific form, ranging from Russia to Indonesia and K. flabellum (Nutting, 1908), which apparently has only been recorded from Hawaii. K. profunda (Wright, 1885), recorded from Alaska and Japan (as noted by B Wing and G Williams in Andrews et al. 2005), was at first thought to be the only species in this genus actually listed for the northeastern Pacific Ocean. However, K. profunda is no longer recognized as belonging to this genus, having been accepted as Bathygorgia profunda Wright, 1885 (Cordeiro et al. 2019).

Of the approximately fourteen specimens identified as belonging to this genus, housed in the collection at CAS, roughly half are from California; the other half from either Alaska or Hawaii. Of these fourteen, most are not identified to species, but of those that are, three of the four species mentioned above are listed, with the two records from California that have species identification listed as K. flabellum and K. philippinensis ; no opportunity to verify those identifications. The southernmost California records seen previously were from Monterey Bay and from the now extensively studied Davidson Seamount; one other specimen from this genus collected/photographed by MBARI (shown on a public website) at Davidson Seamount noted it as being collected at 1,455 m. Searching Excel data sheets from MBARI (provided by L Lundsten in 2008), three dozen or so specimens have been collected over the last few years, but there are many more video observations (many of those will be multiple observations of the same organism) that have been identified as belonging to this genus. NMNH has records of specimens belonging to this genus from both Oregon and Alaska, and of note are several other specimens: those from Fieberling Guyot, 32°26'00"N, 127°47'36"W, 490 m, 16 October 1990; USNM 94443, and those from Rodriquez Seamount, 33°57'12"N, 121°08'41"W, 1840 m, 14 October 2003; USNM 1027077, both of these areas off the California coast.