title: Are Prorocentrum hoffmannianum and Prorocentrum belizeanum (DINOPHYCEAE, PROROCENTRALES), the same species? An integration of morphological and molecular data.
abstract: The taxonomic assignment of Prorocentrum species is based on morphological characteristics; however, morphological variability has been found for several taxa isolated from different geographical regions. In this study, we evaluated species boundaries of Prorocentrum hoffmannianum and Prorocentrum belizeanum based on morphological and molecular data. A detailed morphological analysis was done, concentrating on the periflagellar architecture. Molecular analyses were performed on partial Small Sub-Unit (SSU) rDNA, partial Large Sub-Unit (LSU) rDNA, complete Internal Transcribed Spacer Regions (ITS1-5.8S-ITS2), and partial cytochrome b (cob) sequences. We concatenated the SSU-ITS-LSU fragments and constructed a phylogenetic tree using Bayesian Inference (BI) and maximum likelihood (ML) methods. Morphological analyses indicated that the main characters, such as cell size and number of depressions per valve, normally used to distinguish P. hoffmannianum from P. belizeanum, overlapped. No clear differences were found in the periflagellar area architecture. Prorocentrum hoffmannianum and P. belizeanum were a highly supported monophyletic clade separated into three subclades, which broadly corresponded to the sample collection regions. Subtle morphological overlaps found in cell shape, size, and ornamentation lead us to conclude that P. hoffmanianum and P. belizeanum might be considered conspecific. The molecular data analyses did not separate P. hoffmannianum and P. belizeanum into two morphospecies, and thus, we considered them to be the P. hoffmannianum species complex because their clades are separated by their geographic origin. These geographic and genetically distinct clades could be referred to as ribotypes: (A) Belize, (B) Florida-Cuba, (C1) India, and (C2) Australia.
authors.affiliation: Centro de Investigaciones Biológicas del Noroeste S. C., Avenida Instituto Politécnico Nacional 195, La Paz, BCS 23090, México.
authors.forename: Angélica
authors.initials: A
authors.lastname: Herrera-Sepúlveda
authors.affiliation: Marine Biological Association of the UK, The Citadel, Plymouth, PL1 2BP, UK.
authors.forename: Linda K
authors.initials: LK
authors.lastname: Medlin
authors.affiliation: Centro de Investigaciones Biológicas del Noroeste S. C., Avenida Instituto Politécnico Nacional 195, La Paz, BCS 23090, México.
authors.forename: Gopal
authors.initials: G
authors.lastname: Murugan
authors.affiliation: Centro de Investigaciones Biológicas del Noroeste S. C., Avenida Instituto Politécnico Nacional 195, La Paz, BCS 23090, México.
authors.forename: Arturo P
authors.initials: AP
authors.lastname: Sierra-Beltrán
authors.affiliation: Centro de Investigaciones Biológicas del Noroeste S. C., Avenida Instituto Politécnico Nacional 195, La Paz, BCS 23090, México.
authors.forename: Ariel A
authors.initials: AA
authors.lastname: Cruz-Villacorta
authors.affiliation: Centro de Investigaciones Biológicas del Noroeste S. C., Avenida Instituto Politécnico Nacional 195, La Paz, BCS 23090, México.
authors.forename: Norma Y
authors.initials: NY
authors.lastname: Hernández-Saavedra
keywords: Prorocentrum hoffmanianum species complex; SEM; molecular phylogeny; morphology; taxonomy