Rypticus africanus: A new species of Soapfish from the eastern Atlantic.

Soapfish, Grammistes and Rypticus spp., are bottom-dwelling Perciform Fish related to Groupers, generally found on reefs and other rocky marine environments. They get their common name from their ability to secrete a toxic, soapy, mucus as a defence mechanism. The genus Grammistes is restricted to the Indo-Pacific region, while members of the genus Rypticus are found in the Western Pacific, Atlantic and Caribbean. Only two species of Rypticus have been found on the African coast, the Greater Soapfish, Rypticus saponaceus, and the Spotted Soapfish, Rypticus subbifrenatus. The Greater Soapfish is known from both sides of the Atlantic being found from the coast of Florida, throughout the Caribbean, and as far south as Brazil in the western Atlantic, and from Mauritania south as far as Angola in the eastern Atlantic. However, a genetic study of museum specimens published in 2003 suggested that the eastern and western populations of the Greater Soapfish might in fact be separate species.

In a paper published in the Journal of Fish Biology on 21 July 2025, Gabriel Soares Araujo of the Center for Marine Biology at the University of São Paulo, Cláudio Sampaio of the Laboratório de Ictiologia e Conservação at the Universidade Federal de Alagoas, Luiz Rocha of the  Department of Ichthyology at the California Academy of Sciences, and Carlos Eduardo Ferreira Leite of the Departamento de Biologia Marinha at the Universidade Federal Fluminense, re-examine the genetics of the Greater Soapfish, and formally describe the populations from the African coast as a separate species.

Araujo et al. examined specimens from Cape Verde, Ghana, São Tomé and Príncipe, and Togo. All were found to be genetically distinct from western Atlantic specimens of Rypticus saponaceus, forming a distinct population which is estimated to have split from the west Atlantic population in the Early Pleistocene, about 2.5 million years ago, at the onset of the Pleistocene, and surprisingly being more closely related to the Pacific Rypticus bicolor. Since Rypticus saponaceus was originally described from specimens from Florida, the east Atlantic population is described as a new species, which Araujo et al. name Rypticus africanus.

Time-calibrated phylogeny of the genus Rypticus based on mitochondrial COI gene sequences. Values near the nodes represent estimated divergence times (Mya). The 95% highest posterior density intervals are shown in parentheses. Coloured circles represent the biogeographic regions where species of Rypticus are distributed. Vertical bars depict the results of lineage delimitation tests. Araujo et al. (2025).

Specimens of Rypticus africanus examined range from 112 to 215 mm in length, and have three dorsal fin spines, 22-24 dorsal fin rays, 15-17 anal fin rays, 16-18 pectoral fin rays, and 24-25 caudal (tail) fin rays. The head is distinctly pointed, the dorsal fin originates slightly posterior to upper end the of gill opening, and the tail is rounded. They are brown or dark grey in colour, with numerous pale round spots of variable size on their flanks.

(a)–(c) Rypticus africanus from São Tomé and Príncipe, illustrating the variation in colour pattern between individuals: (a) São Tomé Island, (b), (c) Príncipe Island and (d) Rypticus saponaceus from Salvador, Bahia, Brazil, shown for comparison. Araujo et al. (2025).

Although Rypticus africanus has only been sampled from four areas (Cape Verde, Ghana, São Tomé and Príncipe, and Togo), Araujo et al. believe the name should be applied to all African populations currently described as Rypticus saponaceus, from Mauritania to Angola.

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