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| Plectranthias raki Shepherd, Pinheiro, Najeeb, C. R. Rocha & L. A. Rocha, 2025 |
Abstract
Herein, we describe a new species of Plectranthias perchlet found at depths of 100–125 meters in mesophotic coral ecosystems of the Maldives in the Indian Ocean. Plectranthias raki sp. nov. is unique in both morphology and coloration. The following combination of characters distinguishes it from all known congeners: dorsal fin X, 15; anal-fin rays III, 7; pectoral-fin rays 13 | 13 (13 | 12), all unbranched; principal caudal-fin rays 9 + 8; lateral line complete with 30–32 tubed scales; gill rakers 5 + 12; circumpeduncular scales 11–12; and absence of antrorse or retrorse spines on ventral margin of preopercle. Coloration in life consists of a white to light pink body with two indistinct rows of irregularly shaped red-orange to yellow-orange patches along the dorsal two-thirds of the body, a golden-yellow opercle and maxilla, an indistinct yellow stripe on the dorsal fin, two yellow spots near the base of the anal fin, and two irregularly shaped yellow-orange spots located on either side of centermost caudal-fin rays. With this publication, the genus Plectranthias now comprises 67 valid species. This discovery adds to a strong body of research highlighting the novel biodiversity of mesophotic ecosystems, especially in locations like the Indian Ocean, where few prior ichthyological surveys have been conducted.
Key words: COI gene, deep reefs, ichthyology, Indian Ocean, rebreather diving, taxonomy
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| Holotype (left) and paratype (right) of Plectranthias raki sp. nov. Holotype CAS-ICH 248439 66.2 mm SL, shortly after collection (A), preserved specimen (B) and x-radiograph (C). Paratype LACM 61827, 70.4 mm SL, shortly after collection (D), preserved specimen (E) and x-radiograph (F). Photos: A, D by Luiz Rocha. B, C, E, F by Jon Fong. |
Plectranthias raki sp. nov.
Dhivehi common name: Raki bureki
English common name: Maldivian Perchlet
Diagnosis: Plectranthias raki sp. nov. is unique in both morphology and coloration. The following combination of characters distinguishes it from all known congeners: dorsal fin X, 15; anal-fin rays III, 7; pectoral-fin rays 13 | 13 (13 | 12), all unbranched; principal caudal-fin rays 9 + 8; lateral line complete with 30–32 tubed scales; 3 supraneural bones, predorsal formula 0/0 + 0/2/1 + 1/1/1/; gill rakers 5 + 12; circumpeduncular scales 11–12; oblique rows of scales on cheek 8 (7); longest dorsal spine the ...
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| Living specimen (not retained) of Plectranthias raki sp. nov. photographed at 110 m depth at Dhaalu Atoll, Maldives. Photo by Luiz Rocha. |
Etymology: The species name, raki, means “feeling shy to confront people” in the Dhivehi language. This was chosen because Plectranthias are shy by nature and typically hide from us when we are conducting surveys. To be treated as a noun in apposition.
Bart Shepherd, Hudson T. Pinheiro, Ahmed Najeeb, Claudia R. Rocha and Luiz A. Rocha. 2025. Plectranthias raki (Teleostei, Serranidae), A New Species of Perchlet from mesophotic coral ecosystems of the Maldives. ZooKeys. 1223: 333-344. DOI: doi.org/10.3897/zookeys.1223.135292
