Mitocondrial COI and 16S rDNA sequences support morphological identification and biogeography of deep-sea red crabs of the genus Chaceon (Crustacea, Decapoda, Geryonidae) in the Eastern Central and South Atlantic Ocean.

Mariano Hernández,Teresa Almeida,Roberto Sarralde,Johny Charles Gamatham,Barend Johannes Van Zyl,Luis J López-Abellán,Sebastián Jiménez,Santiago Barreiro,Carlos Hernández-González,Pedro M Herrador-Gómez,M Virginia Martín

doi:10.1371/journal.pone.0211717

Abstract

The geographical spreading of new fishing activities and the increasingly deeper locations of these activities have shown the worldwide distribution of gerionid crabs and new descriptions of Chaceon taxa. However, incomplete penetrance, variable expressivity, and phenotypic overlap make the morphometric identification of these species difficult. In this study, partial sequences of the cytochrome c oxidase subunit 1 (COI) and 16S mitochondrial ribosomal RNA (16S rRNA) genes have been analyzed in Chaceon species from the Eastern Central and South Atlantic and compared with sequences of species from Western Atlantic. Our results corroborate the proposed morphological species and highlight the significant separation of the Eastern Atlantic species and those from Atlantic coasts of South America for both markers (97% Bayesian posterior probability, BPP / 83% Bootstrap replicates, BT). Interestingly, Chaceon sanctaehelenae shows a closer relationship with the species of the American coast than with those from the Eastern Atlantic. On the other hand, while COI marker clearly separates Chaceon atopus and Chaceon erytheiae species (99 BPP / 91% BT), these species share haplotypes for the 16S rRNA marker, pointing to a recent speciation process. Moreover, a close relationship was observed between Chaceon maritae and Chaceon affinis (94% BPP / 77% BT). The topologies of the trees obtained indicate that the ancestor of this genus was closer related to those species from South America than to those from the Eastern Atlantic.

Highlights

Morphological identification of species belonging to the Geryonidae family has been a difficult task in the past for people studying deep-sea resources and marine biodiversity
The absence of stop codons seems to discard the presence of nuclear mitochondrial insertions (Numts) in the sequences
The absence of double bands in PCR and double peaks in the electropherogram of the sequences as well as the similarity among them and with those originals deposited in Genbank seems to discard the presence of nuclear mitochondrial DNA sequences (Numts) in these sequences too

Summary

Introduction

Morphological identification of species belonging to the Geryonidae family has been a difficult task in the past for people studying deep-sea resources and marine biodiversity. Interspecific similarities and intraspecific morphological variability have contributed to former and potential current misclassification [1]. Other considerations such as the geographical site of collections have been an element used in the species identification, regarding previous species citations in the same geographic zone [1, 2, 3]. In 1981, Manning and Holthuis [2] described Geryon maritae as a new species in the Atlantic coast of Africa. These authors reported that most records of Geryon affinis or Geryon quinquedens from West Africa pertained to G. maritae

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