Phylogeny and Cryptic Diversity of Diopatra (Onuphidae, Annelida) in the East Atlantic.

Martin M Hektoen,Endre Willassen,Nataliya Budaeva

doi:10.3390/biology11020327

Martin M Hektoen, Endre Willassen + Show 1 more

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https://doi.org/10.3390/biology11020327

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Abstract

Diopatra Audouin & Milne-Edwards, 1833 is a species rich genus that is common in tropical and subtropical regions. The genus is readily identified by its striking, spiral branchiae, but species identification has historically been challenging due to a high variation in diagnostic characters used. This study aims to reconstruct the phylogeny of Diopatra with molecular markers and assess the species diversity of West African Diopatra with the species delimitation programs bPTP and BPP. Specimens were collected from Morocco to Angola, and the markers COI, 16S and 28S were sequenced from 76 specimens. The constructed phylogeny retrieved Diopatra as monophyletic, as well as five well supported clades within the genus. All clades were defined by morphological characters, some of which have previously not been considered to have high phylogenetic or taxonomical value. Species delimitation analyses recovered 17 new species, several of which were not readily identified morphologically. One species complex comprising between one and 12 species was left unresolved due to incongruence between the species delimitation methods and challenging morphology. Our results indicate that the diversity of Diopatra is significantly underestimated, where this regional study near to doubled the number ofknown species from the East Atlantic.

Highlights

Diopatra Audouin & Milne-Edwards, 1833 [1] is monophyletic [2] and the most speciesrich genus of the family Onuphidae Kinberg, 1865 [3] with approximately 65 species currently known world-wide [4,5]
We study morphological characters that potentially can be used as synapomorphies for major recovered clades within Diopatra and assess the diversity of Diopatra in the East Atlantic by applying two sequence-based species delimitation methods: Bayesian implementation of the PTP model (bPTP) and Bayesian Phylogenetics and Phylogeography (BPP)
The bPTP analyses based on 16S and combined 16S and c oxidase subunit 1 (COI) resulted in 13 putative species, while the COI analysis resulted in 12 putative species

Summary

Introduction

Diopatra Audouin & Milne-Edwards, 1833 [1] is monophyletic [2] and the most speciesrich genus of the family Onuphidae Kinberg, 1865 [3] with approximately 65 species currently known world-wide [4,5]. The genus has several morphological autapomorphies such as spiral gills, serrated limbate chaetae and complex brush-like tubes [6,10,11]. A more detailed phylogeny of the genus utilizing molecular data and including a wide array of species has not been previously inferred. Epidiopatra was proposed to be polyphyletic and was subsequently merged with Diopatra [11], its polyphyly has yet to be confirmed with molecular data

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