Species Delimitation of Southeast Pacific Angel Sharks (Squatina spp.) Reveals Hidden Diversity through DNA Barcoding

Rosa M Cañedo-Apolaya,Joanna Alfaro-Shigueto,Eliana Alfaro-Cordova,Carmen Yamashiro,Jeffrey C Mangel,Raquel Siccha-Ramirez,Ximena Velez-Zuazo,Clara Ortiz-Alvarez,Jorge L Ramirez

doi:10.3390/d13050177

Rosa M Cañedo-Apolaya, Joanna Alfaro-Shigueto + Show 7 more

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https://doi.org/10.3390/d13050177

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Abstract

Angel sharks are distributed worldwide in tropical to subtropical waters. Across the Eastern Pacific Ocean (EPO), two valid species are reported: The Pacific angelshark Squatina californica and the Chilean angelshark Squatina armata; however, there is still uncertainty about their geographic distribution, mainly along the northern Peru coast where the species have been reported to be sympatric. The aim of this study is to describe the genetic differences between the genus Squatina from the EPO, including samples from northern Peru, and using DNA barcoding and three species delimitation models: Poisson tree processes (PTP) model, Bayesian implementation of the PTP (bPTP) model and the general mixed Yule coalescent (GMYC) model. The three approaches summarized 19 nominal Squatina species in 23 consensus Molecular Taxonomic Units (MOTU). Only 16 of them were in accordance with taxonomic identifications. From the EPO, four Squatina MOTUs were identified, one from North America (S. californica USA/Mexico) and three sampled in northern Peru, S. californica Peru, S. armata and Squatina sp. (a potential new species). This study contributes to the management and conservation policies of angel sharks in Peru, suggesting the presence of an undescribed species inhabiting the northern Peruvian coast. The use of molecular approaches, such as DNA barcoding, has the potential to quickly flag undescribed species in poorly studied regions, including the Southeast Pacific, within groups of ecologically and economically important groups like angel sharks.

Highlights

The aim of the present study is to describe the genetic differences within the genus Squatina from the Eastern Pacific Ocean (EPO), including samples of angel sharks from an area not previously covered, and integrate them with mtDNA Cytochrome Oxidase subunit I (COI) sequences data from Barcode of Life Data (BOLD) System to evaluate species boundaries using species delimitation methods and determine Molecular Taxonomic Units (MOTU)
Two valid species had been previously described for the EPO: Squatina californica and Squatina armata [7,10,28], and both species have been reported as sympatric for the northern Peruvian coast [15]
Our results show a new scenario, reporting the existence of four MOTUs along the EPO (Figure 3), revealing a hidden diversity that may include at least one new species for the genus Squatina in the Southeast Pacific

Summary

Introduction

One of the most diverse groups of marine predators is the subclass Elasmobranchii (i.e., sharks, skates, and rays). There is a small but highly distinctive group of bizarrely-shaped benthic sharks, commonly called angel sharks. This group of ray-like sharks belongs to the monophyletic family Squatinidae (Bonaparte, 1838) [1,2,3] encompassing a unique genus, Squatina (Dumeril, 1805), with 22 extant species described based on morphological characters or molecular information [4,5,6,7]. There are two additional species from the Gulf of Mexico described [8], Squatina mexicana Castro–Aguirre, Espinosa–

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