Deep phylogeographic structure may indicate cryptic species within the Sparid genus Spondyliosoma

Abstract

Two geographically nonoverlapping species are currently described within the sparid genus Spondyliosoma: Spondyliosoma cantharus (Black Seabream) occurring across Mediterranean and eastern Atlantic waters from NW Europe to Angola and S. emarginatum (Steentjie) considered endemic to southern Africa. To address prominent knowledge gaps this study investigated range-wide phylogeographic structure across both species. Mitochondrial DNA sequences revealed deep phylogeographic structuring with four regionally partitioned reciprocally monophyletic clades, a Mediterranean clade and three more closely related Atlantic clades [NE Atlantic, Angola and South Africa (corresponding to S. emarginatum)]. Divergence and distribution of the lineages reflects survival in, and expansion from, disjunct glacial refuge areas. Cytonuclear differentiation of S. emarginatum supports its validity as a distinct species endemic to South African waters. However, the results also indicate that S. cantharus may be a cryptic species complex wherein the various regional lineages represent established/ incipient species. A robust multilocus genetic assessment combining morphological data and detailing interactions among lineages is needed to determine the full diversity within Spondyliosoma and the most adequate biological and taxonomic status.

Phylogeography of recent Plesiastrea (Scleractinia: Plesiastreidae) based on an integrated taxonomic approach

“…Cryptic species are defined as two or more morphologically similar but genetically distinct species that are erroneously classified under one species name (Bickford et al, 2007;Fišer et al, 2018;Knowlton, 1993;Sáez and Lozano, 2005). Cryptic species often remain undetected until in-depth phylogeographic (Arrigoni et al, 2019(Arrigoni et al, , 2020Fouquet et al, 2007;Mitsuki et al, 2021;Williams et al, 2006) or population genetic studies reveal unexpected divergences (González-Castellano et al, 2020;Griffiths et al, 2010;McKeown et al, 2020). A large proportion of major metazoan taxa contain cryptic species (Pérez-Ponce de León and Poulin, 2016;Pfenninger and Schwenk, 2007); hence cryptic speciation presents ubiquitous and complex challenges to anyone attempting to use morphological similarities to identify species.…”