Quantitative comparison of taxa and taxon concepts in the diatom genus Fragilariopsis : a case study on using slide scanning, multiexpert image annotation, and image analysis in taxonomy 1

• Published in: Journal of Phycology
• Main Authors: Beszteri, Bank, Allen, Claire, Almandoz, Gaston O., Armand, Leanne, Barcena, María Ángeles, Cantzler, Hannelore, Crosta, Xavier, Esper, Oliver, Jordan, Richard, Kauer, Gerhard, Klaas, Christine, Kloster, Michael, Leventer, Amy, Pike, Jennifer, Rigual Hernández, Andrés S.
• Other Authors: Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung = Alfred Wegener Institute for Polar and Marine Research = Institut Alfred-Wegener pour la recherche polaire et marine (AWI), Helmholtz-Gemeinschaft = Helmholtz Association, British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Universidad Nacional de la Plata Argentine (UNLP), Department of Biological Sciences North Ryde, Macquarie University, Universidad de Salamanca, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Department of Earth and Environmental Sciences Yamagata, Yamagata University, Max-Planck-Institut für Biogeochemie (MPI-BGC), Colgate University, School of Earth and Ocean Sciences Cardiff, Cardiff University
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: [SDV.BID.SPT]Life Sciences [q-bio]/Biodiversity/Systematics; Phylogenetics and taxonomy; [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Southern Ocean
• Online Access: https://hal.science/hal-02105532; https://hal.science/hal-02105532/document; https://hal.science/hal-02105532/file/Beszteri_JPhycol2018.pdf; https://doi.org/10.1111/jpy.12767

International audience Semiautomated methods for microscopic image acquisition, image analysis, and taxonomic identification have repeatedly received attention in diatom analysis. Less well studied is the question whether and how such methods might prove useful for clarifying the delimitation of species that are difficult to separate for human taxonomists. To try to answer this question, three very similar Fragilariopsis species endemic to the Southern Ocean were targeted in this study: F. obliquecostata, F. ritscheri, and F. sublinearis. A set of 501 extended focus depth specimen images were obtained using a standardized, semiautomated microscopic procedure. Twelve diatomists independently identified these specimen images in order to reconcile taxonomic opinions and agree upon a taxonomic gold standard. Using image analyses, we then extracted morphometric features representing taxonomic characters of the target taxa. The discriminating ability of individual morphometric features was tested visually and statistically, and multivariate classification experiments were performed to test the agreement of the quantitatively defined taxa assignments with expert consensus opinion. Beyond an updated differential diagnosis of the studied taxa, our study also shows that automated imaging and image analysis procedures for diatoms are coming close to reaching a broad applicability for routine use.