Research Article |
Corresponding author: Gary C. Williams ( gwilliams@calacademy.org ) Academic editor: James Reimer
© 2021 Gary C. Williams.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Williams GC (2021) The deep-sea pennatulacean genus Porcupinella – with the description of a new species from Tasmania (Anthozoa, Octocorallia, Chunellidae). ZooKeys 1019: 1-14. https://doi.org/10.3897/zookeys.1019.61789
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The recently described deep-sea pennatulacean genus Porcupinella was previously known only by the type species, Porcupinella profunda from the equatorial eastern Atlantic to the eastern North Atlantic Ocean. New data is provided on morphology, distribution, bathymetry, and related taxa. A second species is added here as well – a new species is described from the Tasman Sea in the southwestern Pacific. The new species, Porcupinella tasmanica, is distinguished from P. profunda by its distinctive hook-shaped growth form, laterally compressed dorsal keel, and differing regions that are occupied by siphonozooids. A key to the species of the deep-sea pennatulacean family Chunellidae is included based on comparative morphology.
Deep-sea pennatulaceans, key to chunellid species, Porcupinella tasmanica sp. nov., sea pens, systematics, worldwide distribution
Pennatulaceans or sea pens are a distinctive group of octocoral cnidarians distributed in all oceans of the globe and range in depth from sea level to least 6200 m (
The genus Porcupinella López-González & Williams, 2011 of the pennatulacean family Chunellidae, was named for the type locality of the first described species – the Porcupine Abyssal Plain, southwest of Ireland in the northern Atlantic Ocean (
The Chunellidae is a rarely encountered family of deep-sea pennatulacean octocorals (800–5300 m), currently known from the northeastern Atlantic, southwestern Pacific, and western Indian Oceans. The chunellids are morphologically unique in that they possess a terminal polyp, unlike other pennatulaceans. The terminal polyp in chunellids is a single solitary polyp that is morphologically similar to the other paired autozooids in the colony and occupies the most distal position on the polyp-bearing portion of the rachis (Figs
Porcupinella tasmanica sp. nov. Diagram of external morphology (Holotype, CASIZ 228434). Abbreviations: a – axis; dt – distal terminus of the colony; k – keel of the stalk; la – lateral autozooid, p – peduncle, r – rachis; s – siphonozooid; ta – terminal autozooid; tb – terminal bulb of the peduncle. Scale bar: 10 mm.
An additional species of Porcupinella, collected in May of 2017 from the Tasman Sea off the east coast of Australia at a depth of approximately 4100 m, differs from P. profunda in several morphological aspects and is described here as a new species.
One noteworthy aspect is that the two species of Porcupinella are perhaps the smallest sea pens known, 27–42 mm in recorded length. In addition, the genus Porcupinella is known entirely from depths in excess of 4000 m, which is beyond the depth range of most ROV operations, and thus all collected material to date has been acquired by beam or bottom trawl.
The morphological and anatomical aspects of pennatulaceans have been well documented in various publications (
All known material representing the new species was collected by beam trawl between 4114 and 4139 m off the coast of northeast Tasmania in 2017, and is deposited in the invertebrate zoology collection of the California Academy of Sciences. The material was collected by the Australian marine research vessel, the R/V Investigator, which is managed by the Commonwealth Scientific and Industrial Research Organization (
Material used in the description of the type species of the genus, Porcupinella profunda, was collected by bottom trawl during the BENGAL Program (BENthic biology and Geochemistry of a northeastern Atlantic abyssal Locality) in 1997 and 1998 (
Illustrations of individual colonies of Porcupinella were made using a Nikon 0.7–3.0 zoom dissecting microscope microscope, and were photographed using a Panasonic Lumix DMC-ZS30 camera. Sclerites were isolated from peduncular tissues of the new species using the laboratory technique articulated by
Terminology used in this paper conforms to that of
Class: Anthozoa Ehrenberg, 1834
Subclass: Octocorallia Haeckel, 1866
Order: Pennatulacea Verrill, 1865
Family: Chunellidae Kükenthal, 1902
Mature colony length < 50 mm. Lower rachis region strongly recurved, colonies have an inverted J-shape. Region of strongest curvature forms a laterally flattened keel. Single terminal polyp and generally two pair of lateral polyps congested together in distal region of rachis. Autozooids five to seven in total number. Distal terminus of colony ends in a pointed tip and may form a downward projecting beak-like acute point. Siphonozooids sparsely distributed (< 12 per side), present on upper surface of rachis adjacent and proximal to the lower lateral polyps. Sclerites restricted to minute ovoid bodies in the bulb of the peduncle. Preserved colonies white.
Holotype. CASIZ 228434. Western Pacific Ocean, Australia, Tasman Sea, Flinders Marine Park (40.4732 to 40.464S, 149.3967 to 149.4255E); 4114–4139 m; 20 May 2017; coll. RV Investigator, IN2017_V03_015_011, Beam Trawl; one whole colony wet-preserved in 95% ethanol. Paratype. CASIZ 228435, same data as holotype; one whole colony wet-preserved in 95% ethanol.
CASIZ 228436, same data as holotype, three whole colonies wet-preserved in 95% ethanol.
Known only from the type locality, Flinders Marine Park in the Tasman Sea, 4114–4139 m in depth (Fig.
The specific epithet is derived from “Tasmania” and the Latin suffix –ica (belonging to), in reference to the type locality.
(Figs
Polyps
(Figs
Sclerites
(Fig.
Color
(Figs
Porcupinella tasmanica sp. nov. Micrographs of rachis details A view of the distal portion of the rachis (CASIZ 228436), showing placement of a zone of siphonozooids on the lateral side of the rachis between the terminal and lateral autozooids. The axis is visible just below the surface of rachis B view of the distal terminus of the rachis (CASIZ 228435), showing the axis visible just below the surface of the rachis. A zone of siphonozooids is apparent on the lateral edge of the rachis, between the terminal and lateral autozooids C View of the distal terminal portion of the rachis (CASIZ 228436), showing the terminal autozooid, a whorl of three subtending lateral autozooids, which are in turn subtended by a pair of lateral autozooids. Abbreviations: a – axis; la – lateral autozooid; p – pair of lateral autozooids; r – rachis; s – siphonozooids; ta – terminal autozooid; w – whorl of three lateral autozooids. Scale bar: 4 mm (A); 3 mm (B); 5 mm (C).
Variation. (Figs
Porcupinella tasmanica has a strongly recurved growth form, and the autozooids are on the enlarged rachis, which is distal to the keel and separated from it (Figs
Porcupinella profunda. Diagram of external morphology (CASIZ 180424). Abbreviations: a – axis; dt – distal terminus of the colony; k – keel of the stalk; la – lateral autozooid; p – peduncle, r – rachis; s – siphonozooid ta – terminal autozooid; tb – terminal bulb of the peduncle. Scale bar: 10 mm.
Porcupinella profunda
López-González & Williams, 2011: 311;
(Non-type/Voucher). CASIZ 180424, Northeast Atlantic Ocean, Porcupine Abyssal Plain (48°49.64'N, 16°30.12'W); 4841 m; 17 March 1998; coll. BENGAL cruises (EU Marine Science and Technology Programme, 1994–1998, Bottom Trawl); two whole colonies wet-preserved in 75% ethanol, original fixative 3% buffered formalin. CASIZ 180425, Northeast Atlantic Ocean, Porcupine Abyssal Plain (48°48.30'N, 16°25.97'W); 4839 m; 19 March 1998; coll. BENGAL cruises (EU Marine Science and Technology Programme, 1994–1998, Bottom Trawl); two whole colonies wet-preserved in 75% ethanol, original fixative 3% buffered formalin. CASIZ 180426, Northeast Atlantic Ocean, Porcupine Abyssal Plain (48°47.82'N, 16°40.37'W); 4847 m; 10 January 1998; coll. BENGAL cruises (EU Marine Science and Technology Programme, 1994–1998; Bottom Trawl); two whole colonies wet-preserved in 75% ethanol, original fixative 3% buffered formalin.
Recorded from the eastern Atlantic Ocean from the Porcupine Abyssal Plain (southwest of Ireland), south to equatorial latitudes, 4510–5300 m in depth. (
The six whole colonies from the Porcupine Abyssal Plain that were examined for this study range in length from 29–41 mm (Figs
At least twenty-five collected colonies are known, thirteen of which are deposited at the Muséum national d’Histoire Naturelle (
The pennatulacean family Chunellidae was described by
To date, a robust and reliable molecular analysis has not been accomplished to treat the phylogenetic placement of the genus Porcupinella, due in part to the difficulty of obtaining suitable material for examination at present. One effort has been attempted, however uncertainty exists regarding the valid identification of material used. It was tentatively identified as a species of Porcupinella, but may actually represent the genus Umbellula Gray, 1870 (U. Ganguly, pers. comm.). Since molecular data for taxa within the family Chunellidae does not exist at present, the elucidation of phylogenetic affinities of the genus Porcupinella would require acquiring molecular data for the type species of the genus Chunella (C. McFadden, pers. comm.), which due to the rarity of collected material and the difficulty of obtaining fresh material, is not feasible at present. However, such an overall reliable analysis would potentially corroborate or contradict the placement of the genus in the family Chunellidae and could also elucidate its phylogenetic position among other deep-sea pennatucaeans.
The genus Porcupinella is here included in the family Chunellidae based on several morphological characters, such as possessing a single terminal polyp at the distal end of the rachis, which varies within the family from functional and fully formed (Porcupinella), to modified and zygomorphic (Amphiacme), to highly reduced and rudimentary (Chunella).
Morphological similarities between some species of Umbellula (family Umbellulidae) and chunellids such as Porcupinella have previously been discussed by
1 | Terminal polyp absent |
Calibelemnon spp. |
– | Terminal polyp present | 2 |
2 | Pairs or whorls of lateral polyps separated by conspicuous areas of bare rachis | 3 |
– | Pairs of lateral polyps congested in distal region of rachis near the terminal polyp | 4 |
3 | Terminal polyp rudimentary and highly reduced, tentacles absent | 5 |
– | Terminal polyp fully developed, zygomorphic and laterally compressed, tentacles present | Amphiacme abyssorum |
4 | Colonies crescent-shaped to more-or-less straight. Polyps emanate from the keel-bearing portion of rachis | Porcupinella profunda |
– | Colonies inverted J-shaped, markedly recurved in distal portion of rachis. Polyps remote from the bare keel | Porcupinella tasmanica |
5 | Polyps three per whorl | Chunella gracillima |
– | Polyps two or four per whorl | 6 |
6 | Polyps in pairs (two per whorl) | Chunella biflora |
– | Polyps four per whorl | Chunella quadriflora |
Of the thirty-seven extant genera of pennatulaceans the three deepest known are Kophobelemnon Asbjørnsen, 1856 (36–4900 m), Porcupinella (4114–5300 m) and Umbellula (210–6260 m) (
Three species of Chunella have been described and differentiated on the basis of number of polyps per whorl, which may be due to intraspecific variation, and thus the taxonomic limitations of the genus is dubious at present (
Two species of Porcupinella are known, the type species, P. profunda, from the Atlantic Ocean, and P. tasmanica sp. nov. from the southwestern Pacific.
I extend my thanks to Phil Alderslade and Kirrily Moore, Commonwealth Scientific and Industrial Research Organization (