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| Aliena parva Breedy, McFadden & Cortés, 2023 |
Abstract
Aliena parva gen. et sp. nov. is described from Cocos Island, Costa Rica. The species was found at various islets and rocky outcrops north and northwest of the island, 20–30 m in depth. The genus is characterised by polyps, retracting into calyces, that form thin encrusting mats extending on dead or live substrates. Sclerites are mostly asymmetrical spindles. Anthocodial rods are arranged in points, not forming a collaret. Colonies and coenenchymal sclerites are red, and polyps are transparent. Using an integrative taxonomic approach, we found the new genus to morphologically and genetically differ from all other described taxa. The molecular phylogenetic analyses provide strong support for the placement of this new genus in the family Pterogorgiidae. Morphologically it is unlike any of the other members of this family, necessitating an amendment to the diagnosis of Pterogorgiidae. Like several other known taxa of octocorals with encrusting growth forms, Aliena gen. nov. appears to have evolved from a gorgonian ancestor by loss of an internal skeletal axis. It is the first member of Pterogorgiidae to be reported from the eastern Pacific, contributing further to the knowledge of marine biodiversity in the eastern tropical Pacific and to the octocoral biodiversity of Cocos Island in particular.
Key words: Biodiversity, new genus, new species, oceanic island, soft corals, taxonomy
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| Aliena parva gen. nov. et sp. nov. A holotype, MZUCR 3679 B polyps, partially retracted showing anthocodial sclerites C polyp mounds. (Photographs by Fiorella Vásquez, University of Costa Rica.) |
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| Colonies in situ. A Manuelita Afuera, panoramic view of the wall, 25 m deep. (photograph by Anuar Patjane) B–D Manuelita Canal, 25 m deep (photographs by Avi Klapfer). |
Systematics
SubPhylum Anthozoa Ehrenberg, 1831
Class Octocorallia Haeckel, 1866
Order Malacalcyonacea McFadden, van Ofwegen & Quattrini, 2022
Family Pterogorgiidae McFadden, van Ofwegen & Quattrini, 2022
Genus Aliena gen. nov.
Diagnosis: Colonies are encrusting mats of irregular shape, consisting of clusters of 3–25 polyps that may be interconnected by thin coenenchymal extensions forming bridge-like bands between them. Colonies lack an axis. Polyps are retractile into calyces that are covered by a dense layer of small sclerites producing a granular appearance. Coenenchyme is thin without differential sclerite layers. Coenenchymal sclerites are mostly red asymmetrical spindles with simple tubercles and irregular ends. Anthocodial sclerites are mostly red flat rods, with serrated or prickly borders and sparse thorns on the surface, and spine-like rods. They are arranged “en chevron”, forming points but not a collaret. Flat rods form longitudinal rows along the polyp body. Tentacular sclerites are mostly yellow, biscuit-like rods. Colonies are dark red in life and maintain that colour in ethanol.
Type species: Aliena parva sp. nov. by original designation.
Etymology: Alienus (L) foreign, strange, not related. The generic name refers to the unexpected appearance or unnoticed presence of a new shallow-water taxon. It also alludes to its surprising phylogenetic relationship to a group of gorgonian octocorals, a relationship not predicted by its morphology. Gender feminine.
Aliena parva sp. nov.
Etymology: Parvus (L), in allusion to the small size of the polyps. Gender feminine: parva.
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| Colonies in situ with modified tentacle, January 2022. A Manuelita Canal, 25–30 m deep B Roca Sucia, 25 m deep. |
Odalisca Breedy, Catherine S. McFadden and Jorge Cortés. 2023. An Enigmatic New Octocoral Species (Anthozoa, Octocorallia, Malacalcyonacea) from Isla del Coco National Park. ZooKeys. 1169: 317-331. DOI: 10.3897/zookeys.1169.100576
