Introduction
Umbellula is a sea pen genus of worldwide distribution (Risaro et al., Reference Risaro, Williams, Pereyra and Lauretta2020). Species in the genus are characterized by a long and slender rachis with a cluster of autozooids concentrated at the distal tip of the colony (Williams, Reference Williams1995). For many years, sea pen species with these characteristics have been placed in this genus, but recently it has been shown that what has been described as a single genus in fact represents several genera (López-González and Drewery, Reference López-González and Drewery2022). Some species originally described in the genus Umbellula have recently been moved to the genus Porcupinella (López-González and Williams, Reference López-González and Williams2011) and to the two newly described genera Pseudumbellula and Solumbellula (family Pseudumbellulidae) (López-González and Drewery, Reference López-González and Drewery2022). Additional taxonomic and nomenclatural changes of species in the family Umbellulidae are expected as phylogenetic relationships are explored and resolved. In fact, Hogan et al. (Reference Hogan, Hopkins, Wheeler, Allcock and Yesson2019) revealed that an unidentified species of Umbellula (Umbellula sp. 3) has a bipartite mitochondrial genome (i.e., with two separate chromosomes), while in another unidentified species (Umbellula sp. 1) the genome has a novel gene order relative to other sea pens, indicating a high diversity of gene arrangements. Recently, Kushida et al. (Reference Kushida, Brandt, Reimer, Kise and Poliseno2025) showed that Porcupinella profunda López-González & Williams, Reference López-González and Williams2011 belongs to the family Umbellulidae, not to Chunellidae as originally classified.
Most species of Umbellula have been described from equatorial settings, while high latitudes (>60°) in the northern hemisphere show a paucity of described species of the genus. For instance, Dolan (Reference Dolan2008) assessed that the only Umbellula species reported in eastern Canada was Umbellula monocephalus (now accepted as Solumbellula monocephalus), whose original report had been provided by Jungersen (Reference Jungersen1904) as U. lindahli, resulting from the Ingolf Expedition (1435 fathoms/2624 m in Davis Strait). Similarly, from the same Ingolf Expedition, Jungersen (Reference Jungersen1904) identified U. lindahli in the Denmark Strait (Iceland) at 568 fathoms/1070 m, from bottom temperatures of 4.4°C. Umbellula encrinus has been reported in the Greenland side of Baffin Bay for a long time (Broch, Reference Broch1958).
But since 2008, a large number of benthic surveys has taken place in the region, revealing that the Canadian side of Baffin Bay (West Greenland) is also home to abundant Umbellula colonies, believed to be one of the dominant sea pen taxa in the Eastern Canadian Arctic, found in significant concentrations that are considered to form Significant Benthic Areas (Kenchington et al., Reference Kenchington, Beazley, Lirette, Murillo, Guijarro, Wareham, Gilkinson, Koen-Alonso, Benoit, Bourdages, Sainte-Marie, Treble and Siferd2016). The genus Umbellula has also been reported in Newfoundland (Wareham and Edinger, Reference Wareham and Edinger2007; Baker et al., Reference Baker, Wareham, Snelgrove, Haedrich, Fifield and Edinger2012) and in the east and west sides of Baffin Bay (Jørgensen et al., Reference Jørgensen, Tendal and Arboe2013; Yesson et al., Reference Yesson, Simon, Chemshirova, Gorham, Turner, Hammeken Arboe, Blicher and Kemp2015; Neves et al., Reference Neves, Edinger, Hayes, Devine, Wheeland and Layne2018; Hamel et al., Reference Hamel, Wareham-Hayes and Mercier2020; Long et al., Reference Long, Sparrow-Scinocca, Blicher, Hammeken Arboe, Fuhrmann, Kemp, Nygaard, Zinglersen and Yesson2020; Mallon, Reference Mallon2024) and east Greenland, including Iceland (Jungersen, Reference Jungersen1904; Sanmartín Payá, Reference Sanmartín Payá2004; Meißner et al., Reference Meißner, Brenke and Svavarsson2014, Ólafsdóttir et al., Reference Ólafsdóttir, Burgos and Guðmundsson2026). Both U. encrinus and U. lindahli have been reported in this region. Both species are considered valid (McFadden et al., Reference McFadden, Cordeiro, Samimi-Namin, Williams and van Ofwegen2025) but have also been considered to potentially represent synonyms by Dolan (Reference Dolan2008) and others therein. Whether they are synonyms or not, both species have a quadrangular axis, which clearly distinguishes them from species with a round axis.
Here we provide the first record of Umbellula huxleyi Kölliker, Reference Kölliker1880 for the subarctic Northwest Atlantic (Davis Strait, Canada) and Iceland. U. huxleyi, a species with a round axis, has been reported from the Northeast (NE) Atlantic (Dolan et al., Reference Dolan, Tyler, Yesson and Rogers2013) and Pacific oceans (Williams, Reference Williams1995), having been originally described based on specimens from Japan (Kölliker, Reference Kölliker1880; Matsumoto et al., Reference Matsumoto, Iwase, Imahara and Namikawa2007) and also reported from California (Nutting, Reference Nutting1909). In the NE Atlantic, the species has been reported from the Porcupine Seabight, NW Ireland (Dolan et al., Reference Dolan, Tyler, Yesson and Rogers2013). In this study, we provide a description of U. huxleyi based on specimens from Davis Strait and Iceland and provide DNA sequences (mtMutS, COI, and 28S) to support the species’ presence in this region. We compare our specimens to an U. huxleyi lectotype, as well as a specimen of Umbellula spicata Kükenthal, 1902 (the only other known species of Umbellula with a round axis and lacking sclerites in the rachis) hosted at the UK’s Natural History Museum (NHMUK).
Our Canadian samples were collected using a remotely operated vehicle (ROV), which provided the opportunity to briefly investigate the phenomenon of bioluminescence (i.e., light production by a living organism, Duchatelet and Dupont, Reference Duchatelet and Dupont2025) in situ. While widespread among octocorals, including sea pens, bioluminescence’s ecological roles are still not well understood (Bessho-Uehara et al., Reference Bessho-Uehara, Francis and Haddock2020; DeLeo et al., Reference DeLeo, Bessho-Uehara, Haddock, McFadden and Quattrini2024; Duchatelet et al., 2025), and in situ observations are still uncommon in most parts of the world. Among anthozoans, it is prevalent among octocorals (DeLeo et al., Reference DeLeo, Bessho-Uehara, Haddock, McFadden and Quattrini2024), and it has been suggested to potentially play a role in predation/defense, prey attraction, as well as intraspecific (Duchatelet and Dupont, Reference Duchatelet and Dupont2025 and references therein) and interspecific communication (e.g., Bracken-Grissom et al., Reference Bracken-Grissom, Widder, Johnsen, Messing and Frank2018). Given the limited reports and still sparse knowledge of which sea pen species produce bioluminescence, we also provide in situ imagery of bioluminescence in U. huxleyi collected at 574 m in the Northwest Atlantic.
Materials and methods
Sample collection and processing
Two U. huxleyi colonies were collected in Davis Strait using the ROV ASTRID during dive C0044 aboard CCGS Amundsen on August 3, 2023, from a depth of 574 m (Figure 1, Table 1). Tissue subsamples of the two colonies were preserved in 95–100% ethanol. Colony R44-11 was transferred to 70% ethanol and colony R44-12 was frozen at −20 °C. In addition, one colony with a round axis collected from SW Iceland in 2016 during a scientific bottom trawl survey from depths of 1267–1304 m (Table 1) was frozen at −20 °C after collection and also examined. Specimens’ morphology was examined following terminology by Kölliker (Reference Kölliker1880) and Risaro et al. (Reference Risaro, Williams, Pereyra and Lauretta2020). Dolan (Reference Dolan2008) was also consulted and it provides a detailed account of references to U. huxleyi’s over time.
Location of Umbellula huxleyi colonies from Davis Strait, Canada, Northwest Atlantic and Iceland (stars, this study) in relation to type-location (Kölliker, Reference Kölliker1880) and previous North Atlantic records (California records not shown).
List of Umbellula huxleyi specimens from Davis Strait, Canada (ROV position), and Iceland (trawl start position) included in this study
Table 1 Long description
Columns list specimen identifier, location, latitude north, longitude west, depth in meters, and collection method. Specimen R44-11 is from Davis Strait, Canada at 65 degrees 20.1744 minutes north and 58 degrees 1.2744 minutes west, depth 574 m, method ROV. Specimen R44-12 is from Davis Strait, Canada at 65 degrees 20.1702 minutes north and 58 degrees 1.2918 minutes west, depth 573.8 m, method ROV. Specimen AII16-516-1 is from SW Iceland at 63 degrees 04.0300 minutes north and 26 degrees 28.52 minutes west, depth 1267 to 1304 m, method bottom trawl.
Observations of bioluminescence
An attempt to investigate bioluminescence in situ took place during the ROV dive. The camera used to explore bioluminescence was the Mini Zeus MK III (Insite Pacific Inc.), which collects 1080p/1080i high-definition video and has a 3–129 mm, 30× zoom lens. Most camera settings were kept at default, but we used a low-light setting in the software interface. Unfortunately, no other camera setting information was recorded.
Before the two collected sea pens were placed in the ROV bio-boxes, all the ROV lights were turned off to assess bioluminescence activity. The ROV arm held the sea pen from around the peduncle area, and therefore observations focused on the region above the peduncle. ROV arm motions were limited during the experiment but occurred if bioluminescence activity stopped, to assess whether it would return.
Molecular analyses
DNA was extracted from ethanol-preserved tentacles of all specimens using the QIAGEN DNeasy® Blood and Tissue Kit following the manufacturer’s protocol, with an initial overnight incubation with Proteinase K. Segments of two mitochondrial regions (mtMutS and COI) and one nuclear region (28S) were sequenced. Polymerase chain reactions (PCRs) were performed using gene-specific sets of primers: (1) ND42599F (France and Hoover, Reference France and Hoover2002) and mut3458R (Sánchez et al., Reference Sánchez, McFadden, France and Lasker2003) for the mtMutS gene (McFadden et al., Reference McFadden, Benayahu, Pante, Thoma, Nevarez and France2011), (2) COII8068F (McFadden et al., Reference McFadden, Tullis, Hutchinson, Winner and Sohm2004) and COIOCTR (France and Hoover, Reference France and Hoover2002) for COI, and (3) 28S-Far and 28S-Rab (McFadden & van Ofwegen, Reference McFadden and van Ofwegen2013) for 28S.
The PCR amplification of mtMutS, COI, and 28S sequences was conducted using 12.5 µl of Dream Taq PCR Master Mix 2X (ThermoScientific), 1 µl of template DNA, 0.5 µl of forward primer (10 µM), 0.5 µl of reverse primer (10 µM), and 10.5 µl of water, for a total volume of 25 µl per reaction. Thermocycler settings were: 3 min of initial denaturation at 95 °C, followed by 40 cycles of 30 s denaturation at 95 °C, 30 s annealing at 48 °C, 65 s extension at 72 °C, with a final extension at 72 °C for 4 min.
PCR products were purified using Agencourt AMPure XP Beads (Beckman Coulter) following the manufacturer’s instructions and sent to The Centre for Applied Genomics, Toronto, Canada, for Sanger sequencing. Sequences were visualized and aligned using Geneious Prime 2025.0.3. Obtained sequences have been deposited in GenBank under accession numbers PX147434-PX147433 (COI) and PX363472-PX363473 (mtMutS) for specimens R44-11 and R44-12, respectively. Accession numbers for 28S sequences are PZ370496–PZ370498. The Iceland specimen AII16-516-1 mtMutS GenBank accession number is PZ698542. Sequences were compared to available sequences on GenBank using BLAST (blastn, February 26, 2026, and May 5, 2026, for 28S) using default parameters.
Results
Material examined
Colony R44-11, Davis Strait, Canada, 65.3362 N, 58.0212 W, ROV, 574 m depth, 2.8 °C (see Ecological and environmental information), 1 whole colony, 70% ethanol. Colony R44-12, Davis Strait, Canada, ROV, 65.3362 N, 58.0215 W, 573.8 m depth, 2.8 °C (see Ecological and environmental information), 1 whole colony, frozen at −20 °C, later changed to 70% ethanol. Colony AII16-516-1 (326-3), Iceland, Granton bottom trawl, start position 63.0672 N, 26.4753 W, 1267–1304 m depth (min–max depth of the tow), 4.1 °C, 1 whole colony, frozen at −20 °C, later changed to 70% ethanol. U. huxleyi NHMUK 1881.2.11.25 (lectotype), Challenger stn 235, Japan (35.18 N, 135.65 E), 1033 m depth. U. spicata NHMUK 1914.1.27.1.
Molecular analyses
The mtMutS sequences (671 bp) from all three specimens and COI sequences (775 bp) for the two Davis Strait specimens yielded a 100 % identity match to three colonies identified as U. huxleyi and one Umbellula sp. in GenBank (Table 2). Query coverage ranged between 99% and 100%. The 28S sequences for both samples R44-11 and R44-12 had a 99.85% and 99.84% match to U. huxleyi (100% and 94% query, respectively). The 28S sequences for the Icelandic sample had a 100% identity match to two U. huxleyi specimens (100% and 94% queries) (Table 2). The phylogenetic relationship between U. huxleyi (using at least one of these reference sequences) and other sea pens has been demonstrated elsewhere (García-Cárdenas et al., Reference García-Cárdenas, Núñez-Flores and López-González2020; e.g. Kushida et al., Reference Kushida, Brandt, Reimer, Kise and Poliseno2025).
List of Umbellula huxleyi specimens included in this study, associated accession numbers and their closest GenBank matches, with percent identity (% ident) and query coverage (Qcover) as ratio of match to search length in base pairs
Table 2 Long description
Three specimens are listed by Sample ID, with marker and accession number, closest match accession number, percent identity, query coverage, match taxon, and match reference. Sample IDs are R44-11, R44-12, and AII16-516-1. For R44-11, mtMutS PX363472 matches MK919668 at 100 percent identity and 100 percent query coverage, with additional matches DQ302867 to Umbellula sp. at 100 percent identity and 100 percent query coverage, MT968966 to Umbellula huxleyi at 100 percent and 100 percent, and KF313850 to Umbellula huxleyi at 100 percent and 99 percent. For R44-11, COI PX147434 matches MT952715 at 100 percent and 100 percent and MK919668 at 100 percent and 100 percent, and 28S PZ370497 matches OL741707 at 99.85 percent and 100 percent and MT951917 at 99.84 percent and 94 percent. For R44-12, mtMutS PX363473 matches MK919668 at 100 percent and 100 percent, with additional matches DQ302867 to Umbellula sp. at 100 percent and 100 percent, MT968966 to Umbellula huxleyi at 100 percent and 100 percent, and KF313850 to Umbellula huxleyi at 100 percent and 99 percent. For R44-12, COI PX147433 matches MT952715 at 100 percent and 100 percent and MK919668 at 100 percent and 100 percent, and 28S PZ370498 matches OL741707 at 99.85 percent and 100 percent and MT951917 at 99.84 percent and 94 percent. For AII16-516-1, mtMutS PZ698542 matches MK919668 at 100 percent and 100 percent, with additional matches DQ302867 to Umbellula sp. at 100 percent and 100 percent, MT968966 to Umbellula huxleyi at 100 percent and 100 percent, and KF313850 to Umbellula huxleyi at 100 percent and 99 percent; 28S PZ370496 matches OL741707 at 100 percent and 100 percent and MT951917 at 100 percent and 94 percent.
Taxonomy
Class Octocorallia Haeckel, 1866
Order Scleralcyonacea McFadden, van Ofwegen & Quattrini, 2022
Superfamily Pennatuloidea Ehrenberg, 1834
Family Umbellulidae Lindahl, 1874 (1840)
Genus Umbellula Cuvier, [1797]
Umbellula huxleyi Kölliker, Reference Kölliker1880
Diagnosis
Umbellula colonies without sclerites in the autozooids and rachis and with a round axis. Autozooid-bearing portion of the rachis short with numerous, crowded autozooids arranged in a tight cluster, creating an arrangement compared to a “pompon”. Anthocodiae not especially long and slender (emended from Dolan, Reference Dolan2008).
Description
Colony length between the three colonies ranged between 8 and 59 cm, with peduncles between 2.6 and 8 cm, or 14–33% of total length (Figure 2). A total of 12–28 autozooids were observed, arranged in a radially organized cluster. Autozooid lengths ranged between 12.1 and 22.6 mm (including tentacles, or 7–12.9 mm without tentacles). Autozooids in colony AII16-516-1 were mostly lacking tentacles (due to damage), but measured between 13.3 and 19.3 mm. Autozooid diameters ranged between 1.8 and 3.4 mm.
Images of Umbellula huxleyi colonies from Davis Strait, Canada: a, b) colony R44-11 in situ (green laser points are 10 cm apart in (a) and (c, d) post-collection in seawater (d is close-up of c), (e, f) colony R44-12 in situ, showing bioluminescence of the stalk and base of autozooid cluster (f) and (g, h) post-collection in seawater. Note that although (e) and (f) are images of the same colony, in (f) it is being held by the ROV (see Supplementary material video 1). Sip = siphonozooids, aut = autozooids. Scale bars where present = 1 cm.
Siphonozooids are well preserved in colony R44-11 (originally preserved in 70% ethanol), and visible in colonies AII16-516-1 (Figure 3) and R44-12 (both preserved frozen). Siphonozooids in colony R44-11 have a very noticeable single tentacle and are abundant in the proximal portion of the rachis (Figure 3a,b) as well as between autozooids (Figure 3d). Siphonozooids are dome-shaped in colony R44-11 and colony AII16-516-1 but cannot be distinguished well in sample R44-12, although they are also noticed between autozooids. In colony R44-11, siphonozooids are seen all the way along the length of the axis, stopping at the peduncle. As the siphonozooids approach the peduncle, tentacles are no longer seen and appear like little bumps. The last tentacle was noticed ∼17.6 mm above the top of the peduncle.
Umbellula huxleyi from Davis Strait, Canada (a–f, colony R44-11), (g–h, colony R44-12, after freezing), Iceland (i–m), and specimen 1881.2.11.25 (lectotype) from Japan hosted at the NHMUK (n–p). Arrows in (l) point to protuberances that appeared to be retracted autozooids, but whose examination did not yield autozooids, and br indicates clearly broken/severed autozooids. Scale bars = 2 mm unless specified. No scale bar available for (g), but see Figure 2 for reference.
Tentacles have pinnules distributed in an almost opposite fashion. For colony R44-11, approximately 15 pinnules are found on each side of the tentacle and opposite to one another, with small spaces between them and sometimes a shorter pinnule between them on the same side. Tentacles generally represent about a third of autozooid length, and in some cases less (R44-11). In colony AII16-516-1, tentacles of autozooids are damaged, so it is not possible to assess their actual size. The axis is round (Figure 3f, h, j), measuring ∼2 mm in its thickest measured portion, and no sclerites are present on the autozooids/rachis, only typical round corpuscles in the peduncle.
Colony AII16-516-1 has protuberances in the place of some autozooids (Figure 3l), which were initially thought to represent retracted autozooids (also mentioned by Kölliker, Reference Kölliker1880). However, dissection of the protuberances did not yield retracted polyps inside and could represent the previous location of autozooids.
The colonies described in this study compare to the NHMUK lectotype (1881.2.11.25) in their size, small number of polyps (around 11 in the lectotype), general arrangement of polyps and pinnules, siphonozooids between autozooids and with a single tentacle, lack of sclerites in the rachis, tentacles about a third of autozooid’s length, and a round axis (Figure 3n–o).
Ecological and environmental information
CTD data were not available for the specific location of the ROV samples, but a CTD cast taken from a depth of 554 m (cast 036) deployed 160 m from the ROV dive site on the dive day recorded a bottom temperature of 2.8 °C and salinity of 34.6 PSU. Bottom temperature at the site of colony AII16-516-1 from Iceland was of 4.1 °C. Bottom temperature for Umbellula huxleyi (original description) from Japan was 3.3 °C (Kölliker, Reference Kölliker1880). Colony R44-11 was partially withdrawn into the sediment. Examination of the specimen revealed a very short rachis and peduncle (Figure 2) in comparison to colony R44-12. An unidentified endoparasitic copepod was found inside one of the autozooids in colony AII16-516-1 (Figure 3m) and oocytes were observed in the autozooids of colonies R44-11 and AII16-516-1.
Observations of bioluminescence
The ROV lights were turned off while colonies R44-11 and R44-12 were still anchored to the seafloor, and they were gently disturbed by the ROV arm, but no bioluminescence was noticed. Bioluminescence was only detected when they were removed from the substrate and held by the manipulator arm. Glowing for colony R44-11 was minor (Supplementary material figure S1) in comparison to the observed glow for colony R44-12 (Figure 2F), which is also much larger (Supplementary material video 1). In both cases, bioluminescence was only detected at the base of the autozooids’ cluster and at the stalk.
During our short experiment, we could not clearly discern specific patterns. We did not notice obvious light flashes or waves, and light emission intensity appeared comparable along the stalk, although at times there might have been some subtle variation. At some point, the light appears to run from the proximal to the distal part of the stalk (see Supplementary material video 1 at 00:30–00:34). We also noticed that bioluminescence appeared to turn on and off during the duration of the experiment. It started initially without incentive (other than holding the colonies with the ROV arm), and it continued without arm movement until it faded and stopped. Moving the manipulator arm did not consistently yield a return of bioluminescence.
Comparisons
Currently, the only known Umbellula species with a round axis and lack of sclerites in the autozooids and rachis are U. huxleyi and U. spicata Kükenthal, 1902. We note that although a quadrangular axis is mentioned by Kölliker (Reference Kölliker1880) when describing some of the specimens listed as U. huxleyi, this has been considered an error, and those specimens represent a different Umbellula species (Broch, Reference Broch1958; Dolan, Reference Dolan2008). The species U. spicata is characterized by particularly long and slender anthocodia and has been described from the Indian Ocean (Kükenthal, Reference Kükenthal1915). A colony of U. spicata hosted by the NHMUK (1914.1.27.1) is shown in Figure 4 for comparison. Autozooids in this species are thin and can reach 40 mm in length (Thomson and Henderson, Reference Thomson and Henderson1906) (published as Umbellula pendula) or more (see Figure 4), in striking contrast to the observed in U. huxleyi (including this study, maximum length of 22.6 mm). While the type location of U. huxleyi is in the Pacific Ocean, the species has been reported in the NE Atlantic in the primary literature (Dolan et al., Reference Dolan, Tyler, Yesson and Rogers2013), and attested by DNA sequences deposited in GenBank by subject matter experts (e.g., García-Cárdenas et al., Reference García-Cárdenas, Núñez-Flores and López-González2020).
Colony of Umbellula spicata hosted at the NHMUK (1914.1.27.1).
Therefore, its presence in Davis Strait and Iceland complements the known distribution range for the species in the North Atlantic. From a morphological perspective, our specimens match U. huxleyi. One difference noted was the description by Dolan (Reference Dolan2008) and Kükenthal (Reference Kükenthal1915) that tentacles in this species generally represent equal length to the anthocodia, while in our specimens (R44-11 and R44-12) tentacles represented between 32% and 48% of total autozooid length (including tentacles), or 47–92% of autozooid length excluding tentacles. Examination of specimen 1881.2.11.25 (lectotype) corroborates our observations of tentacles not always as large as the autozooid (Figure 3).
From a molecular perspective, our specimens match U. huxleyi colonies identified from the NE Atlantic, outside and far from its type-location. The fact that the species was originally described from the Pacific Ocean and later reported in the NE Atlantic does raise flags regarding the potential for the Atlantic colonies to represent a different species. Nevertheless, while molecular data is not yet available for Pacific Ocean specimens for comparison, the species can be considered to be present in both oceans. The systematics of Umbellula is challenging due to their few distinguishable morphological characters (Dolan, Reference Dolan2008; Risaro et al., Reference Risaro, Williams, Pereyra and Lauretta2020) and diverse genome (Hogan et al., Reference Hogan, Hopkins, Wheeler, Allcock and Yesson2019). Therefore, species status and nomenclature are subject to change in the future, as additional samples and new molecular data become available.
Discussion
U. huxleyi in Davis Strait and Iceland
The specimens of U. huxleyi were collected in Davis Strait (within Canada’s Exclusive Economic Zone) at 574 m (Figure 1, Table 1), and in Iceland at 1267-1304 m, both of which fall within the known bathymetric range of the species (317–2069 m) (Dolan, Reference Dolan2008), although specimens are usually found in waters >1000 m. Umbellula huxleyi’s holotype from Japan was collected from a depth of 565 fathoms (~1033 m) (Kölliker, Reference Kölliker1880).
The identification of U. huxleyi in Davis Strait and Iceland is in line with a recent finding of the octocoral Ceratocaulon wandeli in the area (Neves et al., Reference Neves, Lacasse, Dove, Munro, McFadden and Hayes2025), which had only been previously reported in Iceland and Faroe Islands (López-González et al., Reference López-González, Sanmartín-Payá and Williams2024). Davis Strait represents an interface between the Arctic and the NW Atlantic and appears to host deep-water coral taxa that are not very common in the NW Atlantic, as evidenced by C. wandeli and now U. huxleyi.
Scientific bottom trawl surveys in the area have recovered abundant specimens of Umbellula with a quadrangular axis (identified as U. encrinus), but other Umbellula species, such as U. huxleyi, are still believed to be rare in the region. This aligns well with observations in Icelandic waters (Ólafsdóttir et al., Reference Ólafsdóttir, Burgos and Guðmundsson2026). Our finding of the species at a depth of 574 m in Canada indicates that limited deep-water trawl surveys (≤1500 m) is not the only reason for the lack of records of this species in the region until now.
It is also possible that specimens of U. huxleyi have been caught in bottom trawl surveys in the region but identified at sea as Umbellula sp. and not further examined (i.e., discarded). All specimens brought back to the lab and examined had a quadrangular axis. We therefore recommend at sea examination of Umbellula specimens to also include observation of axis shape (i.e., quadrangular vs. round) as well as sclerites presence in the anthocodia to facilitate locating additional specimens of U. huxleyi and other Umbellula species during these surveys, which represent the backbone of benthic epifauna sampling in the region.
Observations of bioluminescence
Bioluminescence has been reported in other species of Umbellula, including Umbellula magniflora (Widder et al., Reference Widder, Latz and Case1983), Umbellula thomsoni (Tizard et al., Reference Tizard, Moseley, Buchanan and Murray1885), an unidentified Umbellula species (Bessho-Uehara et al., Reference Bessho-Uehara, Francis and Haddock2020), and U. huxleyi (Herring, Reference Herring1991). Although, to our knowledge, this is the first study to show in situ evidence of bioluminescence for the species, Herring (Reference Herring1991) did report on bioluminescence in U. huxleyi colonies collected from stations between 980 and 2010 m from the Porcupine Seabight. It should be noted that Herring’s observations took place onboard the vessel, not in situ. Our U. huxleyi colonies also displayed post-collection glowing after gently rubbing the stalk tissue even in air, as has U. encrinus (B.M. Neves, personal observation).
Tizard et al. (Reference Tizard, Moseley, Buchanan and Murray1885) reported that in a trawled colony of U. thomsoni from the Challenger Expedition, both polyps and the stalk exhibited ‘phosphorescence’. Herring (Reference Herring1983, Reference Herring1991) indicated that bioluminescence was elicited after collection and in tanks, with different parts of the colony emitting different colors: most of the stalk emitted a bright green light, the distal tip of the stalk and base of the polyps emitted a clear blue light. Widder et al. (Reference Widder, Latz and Case1983) showed that in U. magniflora, bioluminescence emissions also varied depending on the location on the colony, ranging between green and blue. Bessho-Uehara et al. (Reference Bessho-Uehara, Francis and Haddock2020) showed that green bioluminescent light was emitted in situ from the polyps of Umbellula sp. upon stimulation by the ROV manipulator arm. In our case, only bioluminescence of the stalk was observed (i.e., autozooids were not seen to emit light). We acknowledge that this could be a detection issue resulting from limitations of the recording system, rather than an actual lack of bioluminescence in the autozooids (the base of the autozooid clusters showed bioluminescence). The same can be said regarding bioluminescence not being detected while the colonies were still anchored in the seafloor.
While our study did not aim to study bioluminescence in the species, our observations provide additional information regarding potential triggers (e.g., physical contact with ROV manipulator arm) and location of light emissions (i.e., stalk). Additional studies are required to assess whether autozooids also have the potential to emit light and what other potential triggers might exist. We also note that in our study, bioluminescence of U. huxleyi was detected in situ using a deep-sea camera with a low-light setting, but opportunistically. Experimenting with camera settings and turning ROV lights off during a dive when possible is encouraged to assess the phenomenon and collect additional in situ behavioural data about these still poorly studied animals.
Supplementary material
The supplementary material for this article can be found at https://doi.org/10.1017/S0025315426101635
Acknowledgements
We thank CCGS Amundsen’s captain and crew, chief scientist David Cote, ROV pilots (C. Morrissey, P. Lockhart, R. Prevost, and S. Jones), and Amundsen Science for enabling the collection of the 2023 samples. We also thank the RV Árni Friðriksson’s captain and crew, as well as researchers of the Marine and Freshwater Research Institute (Iceland) for facilitating the collection of the Icelandic sample. Miranda Howel at the Natural History Museum in London is also thanked for access to the Umbellula specimens in the museum’s collection. Cynthia Mercer (DFO-NL) is thanked for inventorying Umbellula skeletons. Ship time for our leg of the 2023 expedition was provided by Fisheries and Oceans Canada through the Marine Conservation Targets program (NL Region), the Nunatsiavut Government, and Amundsen Science. We also thank two anonymous reviewers for their thoughtful comments and suggestions.
Author contributions
B.M.N. conceived the study, planned ROV survey, collected samples, and conducted morphological analysis; S.O. provided data and sample; B.M.N., R.D., and H.M. conducted the molecular analyses; B.M.N. and V.H. discussed the species status and processed samples at sea; B.M.N. drafted the original manuscript and produced all final figures. All authors read, provided input, and approved the manuscript.
Declaration of interest
The authors declare none.
Data availability statement
The data generated and analyzed during this study are provided in the manuscript, with the genetics data deposited in GenBank under the accession numbers listed in the manuscript.
Ethics and approach
All applicable international, national, and/or institutional guidelines for animal testing, animal care, and use of animals were followed by the authors. No animal testing was performed during this study.
Funding statement
This research received no specific grant from any funding agency, commercial or not-for- profit sectors.
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