Flatfoot in Africa, the cirripede Chthamalus in the west Indian Ocean

Noa Simon-Blecher; Avi Jacob; Oren Levy; Lior Appelbaum; Shiran Elbaz-Ifrah; Yair Achituv

doi:10.7717/peerj.11710

Flatfoot in Africa, the cirripede Chthamalus in the west Indian Ocean

PeerJ. 2021 Jul 8:9:e11710. doi: 10.7717/peerj.11710. eCollection 2021.

Authors

Noa Simon-Blecher¹, Avi Jacob¹, Oren Levy¹, Lior Appelbaum^{1

2}, Shiran Elbaz-Ifrah¹, Yair Achituv¹

Affiliations

¹ The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
² The Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, Israel.

Abstract

Barnacles of the genus Chthamalus are commonly encountered rocky intertidal shores. The phylogeography of the different species in the Western Indian Ocean is unclear. Using morphological characteristics as well as the molecular markers mitochondrial cytochrome oxygenase subunit I (COI) and the nuclear sodium-potassium ATPase (NaKA), we identified four clades representing four species in the Western Indian Ocean and its adjacent seas. Among these species, a newly identified species, Chthamalus barilani, which was found in Madagascar, Zanzibar and Tanzania. Chthamalus from the coasts of Tanzania and Zanzibar is identified morphologically as C. malayensis, and clusters with C. malayensis from the Western Pacific and the Indo Malayan regions. C. malayensis is regarded as a group of four genetically differentiated clades representing four cryptic species. The newly identified African clade is genetically different from these clades and the pairwise distances between them justify the conclusion that it is an additional cryptic species of C. malayensis. This type of genetic analyses offers an advantage over morphological characterization and allowed us to reveal that another species, C. barnesi, which is known from the Red Sea, is also distributed in the Arabian Sea and the Persian Gulf. We could also confirm the presence of the South African species C. dentatus in the Mozambique channel. This represents the Northeastern limit of C. dentatus, which is usually distributed along the coast of southern Africa up to the Islands of Cape Verde in West Africa. Altogether, based on a combination of morphology and genetics, we distinct between four clusters of Chthamalus, and designate their distribution in the West Indian Ocean. These distinctions do not agree with the traditional four groups reported previously based merely on morphological data. Furthermore, these findings underline the importance of a combining morphological and genetics tools for constructing barnacle taxonomy.

Keywords: Barnacles; COI; Cirripedia; Cryptic species; Madagascar; NaKA; New species; Tanzania; Zanzibar.

Grants and funding

This study was supported by grant 574/14 of the Israel Science Foundation (ISF) to Yair Achituv: “Following Darwin: The evolution of the acorn barnacles”. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.