DNA Barcoding for Delimitation of Putative Mexican Marine Nematodes Species

Arely Martínez-Arce,Francesca Leasi,Alberto De Jesús-Navarrete

doi:10.3390/d12030107

Arely Martínez-Arce, Francesca Leasi + Show 1 more

Open Access

https://doi.org/10.3390/d12030107

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Abstract

Nematode biodiversity is mostly unknown; while about 20,000 nematode species have been described, estimates for species diversity range from 0.1 to 100 million. The study of nematode diversity, like that of meiofaunal organisms in general, has been mostly based on morphology-based taxonomy, a time-consuming and costly task that requires well-trained specialists. This work represents the first study on the taxonomy of Mexican nematodes that integrates morphological and molecular data. We added eleven new records to the Mexican Caribbean nematode species list: Anticomidae sp.1, Catanema sp.1, Enoploides gryphus, Eurystomina sp.1, Haliplectus bickneri, Metachromadora sp.1, Odontophora bermudensis, Oncholaimus sp.1, Onyx litorale, Proplatycoma fleurdelis, and Pontonema cf. simile. We improved the COI database with 57 new sequences from 20 morphotypes. All COI sequences obtained in this work are new entries for the international genetic databases GenBank and BOLD. Among the studied sites, we report the most extensive species record (12 species) at Cozumel. DNA barcoding and species delineation methods supported the occurrence of 20 evolutionary independent entities and confirmed the high taxonomic resolution of the COI gene. Different approaches provided consistent results: ABGD and mPTP methods disentangled 20 entities, whereas Barcode Index Numbers (BINs) recovered 22 genetic species. Results support DNA barcoding being an efficient, fast, and low-cost method to integrate into morphological observations in order to address taxonomical shortfalls in meiofaunal organisms.

Highlights

Nematodes are hyper-diverse, abundant, and distributed worldwide [1]
We report for the first time meiofaunal nematode species from the Cozumel Island, namely
Analytical methods Automatic Barcode Gap Discovery (ABGD) and mPTP supported the presence of the 20 species identified morphologically

Summary

Introduction

Nematodes are hyper-diverse, abundant, and distributed worldwide [1]. In the presence of high inputs of organic matter, their abundance increases, helping to regulate this resource. They are a source of high-quality food for other animals [8,9,10,11]. About 20,000 nematode species—of which 6500 are marine benthic (= meiofaunal)—have been formally described [12,13], with estimates ranging between 0.1 and 100 million species [14]. Gathering evidence of nematode diversity and distribution, increasing the record of marine nematodes species, especially in overlooked regions, is nowadays crucial [15]

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