Plectranthias raki is a New Species of Perchlet from the Maldives

A new species of Plectranthias has been described from the Twilight Zone of the Indian Ocean. The Maldivian Perchlet, Plectranthias raki, was found at depths of 100–125 meters in mesophotic coral ecosystems on two atolls in the Maldives.

It differs from its congeners in its fin ray counts and colouration, and the new Maldivian Perchlet takes the total number of Plectranthias species to 67. The Holotype is 66mm in length and the new species was seen inhabiting small holes of reef walls at several locations between Rasdhoo and Dhaalu atolls at approximately 100 to 125 m depth. It was collected using hand nets by B Shepherd, HT Pinheiro, MV Bell, and LA Rocha, while diving on a mixed-gas closed-circuit rebreather on the 9th of December 2022, and the preserved specimens were later measured and x-radiographed at the California Academy of Sciences.

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 hid from the researchers when they were conducting surveys.

The research article published in the Journal Zookeys says that “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.”

“Mesophotic coral ecosystems (MCEs), coral reef habitats found at depths of 30–150 m commonly known as the coral reef “twilight zone,” are home to a diversity of organisms that are largely distinct from their shallow-water counterparts (Rocha et al. 2018). While conducting ichthyological and ecological surveys of MCEs at various locations around the globe, our team has encountered many undescribed species, especially from the families Labridae, Pomacentridae and Serranidae (Arango et al. 2019; Shepherd et al. 2019; Tea et al. 2019; Pinheiro et al. 2019; Shepherd et al. 2021). Recent research expeditions in the Maldives have revealed a similar pattern of discovery.”

Citation

Shepherd B, Pinheiro HT, Najeeb A, Rocha CR, Rocha LA (2025) Plectranthias raki (Teleostei, Serranidae), a new species of perchlet from mesophotic coral ecosystems of the Maldives. ZooKeys 1223: 333-344. https://doi.org/10.3897/zookeys.1223.135292

Main image

Living specimen (not retained) of Plectranthias raki sp. nov. photographed at 110 m depth at Dhaalu Atoll, Maldives. Photo by Luiz Rocha.