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| Pyrolycus jaco Frable, Seid, Bronson & Møller, 2023 |
Abstract
A new species of the zoarcid genus Pyrolycus Machida & Hashimoto, 2002, Pyrolycus jaco sp. nov., is described from a hydrothermal seep environment named Jacó Scar in the eastern Pacific of Costa Rica. Four specimens were collected in 2018 between 1746–1795 m among tubeworm colonies around the seep. The new species is differentiated from its two western Pacific congeners by having a shorter head, snout, jaw, and pectoral fins. It is further diagnosed by having three postorbital pores and two occipital pores. Molecular sequences of the cytochrome c oxidase I gene are provided and are the first for the genus. The character states indicating miniaturization in this species are discussed. This is the first vertebrate species known from this composite reducing ecosystem and is the fourth hydrothermally-associated zoarcid from the eastern Pacific.
Key words: Jacó Scar, Lycodinae, methane seep, Reducing ecosystem, Zoarcoidei
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| Holotype of Pyrolycus jaco sp. nov., SIO 20-41, 107+ mm SL, Jacó Scar, Costa Rica A) freshly collected; B) in preservation, note caudal region removed by collectors; C) superimposition of radiograph over fresh image to estimate vertebral count. Scale bar= 20 mm. |
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| Live images of Pyrolycus jaco sp. nov., not collected, living among Lamellibrachia barhami and Escarpia spicata colonies. Photo credit: ROV SuBastian/Schmidt Ocean Institute. |
Pyrolycus jaco sp. nov.
Diagnosis. A species of Pyrolycus differentiated from its congeners with the following combination of characters: five suborbital bones (vs. six) with 5 pores, occipital pores 2, postorbital pores 3, vertebrae 23 + ~57 = ~80, vomerine and palatine teeth present, total gill rakers 2–3+13–15= 16–17, pectoral fin rays 14–15, upper jaw short 33.9–42.4% HL and snout short 21.3–24.3% HL. It is specifically separated from Pyrolycus moelleri in having fewer precaudal vertebrae and total vertebrae, palatine teeth present (vs. absent), three postorbital pores (vs. two) and 14–15 pectoral-fin rays (vs. 13–14). And from P. manusanus by having two occipital pores (1-0-1 vs. one, 0-1-0), more gill rakers, fewer vomerine teeth, more palatine teeth, fewer pectoral-fin rays, a larger eye diameter, and a narrower gill slit.
Etymology. Named for the type locality and only known habitat, the Jacó Scar site on the Pacific Costa Rica margin, which itself is named in honor of the nearby coastal district of Jacó, Puntarenas, Costa Rica. Name treated as an appositional noun.
Habitat and distribution. Specimens were collected or observed in association with colonies of the tubeworms Lamellibrachia barhami and Escarpia spicata at depths of 1604–1854 m exclusively at Jacó Scar.
Benjamin W. Frable, Charlotte A. Seid, Allison W. Bronson and Peter Rask Møller. 2023. A New Deep-sea Eelpout of the Genus Pyrolycus (Teleostei: Zoarcidae) associated with A Hydrothermal Seep on the Pacific Margin of Costa Rica. Zootaxa. 5230(); 79-89. DOI: 10.11646/zootaxa.5230.1.5
