Phylogeny of the Sepia officinalis species complex in the eastern Atlantic extends the known distribution of Sepia vermiculata across the Benguela upwelling region

Abstract

In order to manage expanding cephalopod fisheries appropriately, accurate species identification and biogeographic characterisation are fundamental. This study addressed such topics within the Sepia officinalis species complex (Sepia officinalis, Sepia hierredda and Sepia vermiculata) with emphasis on African waters. Samples from the currently presumed distributions of S. vermiculata and S. hierredda (South Africa and Ghana/Angola respectively) were sequenced for the cytochrome c oxidase subunit I (COI) and the cytochrome b (cytb) genes of the mitochondrial genome, and compared to existing S. officinalis sequences. Three highly divergent and reciprocally monophyletic clades corresponding to S. officinalis, S. hierredda and S. vermiculata were resolved, representing the first molecular confirmation of the distinct species status of S. hierredda and S. vermiculata. Sequences also revealed that, contrary to expectations based on presently published information, all samples from southern Angola were S. vermiculata. This indicates that the species range extends beyond the currently described northern limit and that S. hierredda and S. vermiculata may be indiscriminately harvested in Angolan waters. Finer scale patterns within S. vermiculata phylogeography also indicate that the Benguela Current System and/or other environmental factors serve to isolate northern and southern stocks.

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

“…The BUS has been identified as the prominent driver of divergence across the SE Atlantic region, generating isolated populations as well as endemic lineages and species in South African waters (Gwilliam et al, 2018; Henriques et al, 2012, 2014; Reid et al ., 2016; Sala‐Bozano et al ., 2009; Schwaninger, 2008; Teske et al ., 2011). However, for some groups the BUS exhibits varying levels of historical and/or recurrent permeability permitting bi‐directional (Henriques et al ., 2015) or asymmetric (Healey et al ., 2017) gene flow. Here the mtDNA divergence of South African S. emarginatum from the geographically most close Angolan “ S. cantharus ” reveals no evidence of such permeability and confirms the long‐term isolation of these groups.…”

“…However, for some groups the BUS exhibits varying levels of historical and/or recurrent permeability permitting bi-directional (Henriques et al, 2015) or asymmetric (Healey et al, 2017) T A B L E 4 Summary of nuclear genetic variation for the Mossel Bay, False Bay, Namibe and Benguela samples described using allele number (N a ), allelic richness (A R ), expected (H E ) and observed (H O ) heterozygosities and probability of conformance to the Hardy-Weinberg equilibrium (P HWE ) of within/between clade sequence divergence exceed barcode gaps for species delineation suggested for fish (Ward et al, 2009). In light of criticisms of species delimitation based solely on mtDNA (reviewed in Hudson & Coyne, 2002;Hudson & Turelli, 2003;Moritz & Cicero, 2004;Sites & Marshall, 2004) confirmatory evidence from other approaches is recommended (Funk & Omland, 2003;Gwilliam et al, 2018).…”

Molecular characterization of four Mullet species based on SCoT and ISSR markers

“…Studying the evolution and phylogenetic relationships of the aquatic organism including fish species were created by analysis of partial sequencing of certain mitochondrial genes such as12s rRNA, 16s rRNA, COI, D-Loop and cytochrome b. (Carvalho and Hauser, 1994;Healey et al, 2017) and concerning mullet fishes among some Mugilidae fishes (Abudefduf vaigiensis, Labracinus cyclophthalmus and Oryzias latipes (Durand et al, 2012). Saad et al (2019) studied the sequencing of Sox14 gene to identify the molecular variations among three mullet fishs (M. seheli, L. carinata and M. cephalus) comparatively with COI barcoding system.…”