Primnoa pacifica Kinoshita, 1907

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 : 254-255

Primnoa pacifica Kinoshita, 1907

Primnoa pacifica Kinoshita, 1907: 232; 1908a: 42-45, text figs 8-9, pl 3, figs 19-20, pl 6, fig. 49; 1908b: pl 18, fig. 3; 1909: 2, 3, text fig. Wing and Bernard 2004: 24, fig. 15. Cairns and Bayer 2005: 233-239. Stone and Shotwell 2007: 72, 93, 107, in situ fig. 2.23. Whitmire and Clarke 2007: 152 (listed). Cairns and Bayer 2009: 30 (listed). Cairns 2011: 19.

Primnoa resedaeformis var. pacifica Kukenthal, 1915b: 146; 1919: 361-362. Aurivillius 1931: 295-296.

Primnoa japonica Verrill, 1922: 15 (nomen nudum).

Primnoa resedaeformis pacifica Kukenthal, 1924: 267, fig. 152. Heifetz et al. 2005: 132.

Primnoa resedaeformis forma pacifica Broch, 1935: 29-33, figs 17a-e, 18a; 1940: 20, 21. Naumov 1955: 66, pl 11, fig. 5.

Material examined.

No specimens in SBMNH collection (see Appendix 3: List of material examined).

Remarks.

Members of this genus display, in texture and color (when preserved in alcohol) that reminiscent of large-curd cottage cheese, arranged into branches. P. resedaeformis from the Atlantic is known to Canadian fishermen commonly as Seacorn or Popcorn coral. (On a first examination of preserved specimens, which were creamy yellow-white in alcohol, the appearance of popcorn immediately came to mind.) Information given here primarily focuses on Primnoa pacifica typical; known distribution ranges from Honshu, Japan; California, north to at least the Aleutian Islands and Gulf of Alaska ( Cairns and Bayer 2005). P. pacifica is known by some (anecdotal, via fishermen working in the Pacific) as Red tree coral (when living, the colony’s pink color is quite beautiful), as well as Seacorn or Popcorn coral.

This species has now been synonymized with P. willeyi Hickson, 1915, following work done by Cairns and Bayer (2005, 2009); this is shown in the WoRMS Database (Cordeiro et al. 2019), where it is considered in the Database as Primnoa pacifica var. willeyi (Hickson, 1915).

Research staff at OCNMS originally believed that Primnoa occurred only on hard substrates (such as large boulders, and exposed bedrock) in areas of low turbidity, at a minimum yearly temperature of 3.7 °C, at depths of at least 9-800 m ( Brancato et al. 2007). However, the OCNMS expedition in May of 2006 noted its location at several sites having muddy or sandy bottoms.

Verrill noted, in his original unpublished notes for the ‘Blake’ Expedition manuscript (transcribed by Bayer in personal notes but not published with the plates in Bayer and Cairns 2004) that in the deep sea, because of the "absolute stillness of the water," many deep-dwelling forms exhibited extreme delicacy and fragility. He noted that numerous examples of the more delicate features occurred in the family Primnoidae . At depth, this species has been found with crinoids intertwined amongst its branches; it may further provide shelter within its branches for species of deep-water rockfish ( Brancato et al. 2007). While Verrill noted (unpublished personal note transcriptions made by Bayer) that many of the deep-sea Alcyonaria are “phosphorescent” (bioluminescent), no recent information was found that could confirm/deny that characteristic for this species, or any other in the family.

The specimen mentioned in the Appendix 3: Other material, may be the southern-most report in eastern Pacific (USA) waters for a specimen of this genus and species. Occurring as far south as La Jolla, California, it may also be found further north into the California Bight, perhaps off the Channel Islands, in deep water. Of the thirteen genus records noted at CAS, the majority of specimens are from Alaska; their only record of this species is from the Sea of Japan. MBARI has records (provided by L Lundsten) for colonies known to belong in the Family Primnoidae , but most are not identified to genus or species. It would not be surprising if some of those specimens represent species within this genus, if not this species. As this manuscript was in preparation, a colony fragment (this genus and likely this species) was located (by myself and my research student, C Schaefer, in 2015) in material sampled from LACoMNH; fragment was found in fishing nets in 1981, set in SW Alaskan waters.