DNA Barcoding for Delimitation of Putative Mexican Marine Nematodes Species

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.

Identification of Vicia Species Native to South Korea Using Molecular and Morphological Characteristics

“…Similarly, morphological markers have been studied in combination with molecular markers as an efficient method of species classification ( Carneiro de Melo Moura et al, 2019 ; Xie et al, 2019 ; Martínez-Arce et al, 2020 ). Morphological data always play a key role in plant species classification based on phylogeny ( Scotland et al, 2003 ).…”

“…However, morphological studies require in-depth knowledge of characteristics or the number of species. Molecular tools using DNA barcodes for taxonomic identification, species delimitation, and access to phylogeny have the potential to overcome these difficulties faced by taxonomists ( Martínez-Arce et al, 2020 ). However, it is very difficult to resolve recently diverged species or new species generated through hybridization if there is no universal sequence of common region as DNA barcode, and sufficient sequence divergence preserved in the domains of all living organisms is necessary for species classification ( Ali et al, 2014 ).…”

New host record, Sclerophrys regularis (Bufonidae), for Rhabdias africanus (Rhabdiasidae, Kuzmin, 2001) based on molecular and morphological evidence

“…Nematodes are a highly diverse worm taxon, that includes both free living and parasitic species ( Martínez-Arce et al, 2020 ). One of nematodes genus, Rhabdias Stiles and Hassall, 1905 which belongs to Rhabdiasidae, comprises more than 80 known species of lung-dwelling parasites of cold blooded animals including amphibians and reptiles ( Kuzmin et al, 2020 ).…”

Uncovering the shell game with barcodes: diversity of meiofaunal Caecidae snails (Truncatelloidea, Caenogastropoda) from Central America

“…In the past fifteen years molecular barcoding and molecular species delineation have revolutionized the assessment of species diversity and traditional taxonomy, allowing for fast and reproducible species identification and delimitation, and adding to objectivity and reliability in species diagnoses (Leasi et al 2013;Fontaneto et al 2015;Scarpa et al 2016;Martínez-Arce et al 2020). Molecular data enables testing for morphologically cryptic species as well as phenotypic plasticity, and the evaluation of intraversus inter-specific variability (Jörger et al 2012;Leasi et al 2013Leasi et al , 2016.…”