Hidden diversity under morphology–based identifications of widespread invasive species: the case of the ‘well–known’ hydromedusa Craspedacusta sowerbii Lankester 1880

Abstract

2019. Hidden diversity under morphology-based identifications of widespread invasive species: the case of the 'well-known' hydromedusa Craspedacusta sowerbii Lankester 1880. Animal Biodiversity and Conservation, Doi: https://doi. AbstractHidden diversity under morphology-based identifications of widespread invasive species: the case of the 'wellknown' hydromedusa Craspedacusta sowerbii Lankester 1880. A relatively scarce number of morphological features available for delimiting closely related species and an increasingly worrisome scenario on Global Climate Change causing the rapid dispersion of invasive alien species can lead to the rapid spread of reports of a given species around the world. Craspedacusta sowerbii Lankester, 1880 is considered the most widespread freshwater jellyfish species and has been reported in numerous locations on all continents except Antarctica. Recently, a few medusae attributed to C. sowerbii were collected from a water reservoir (Bin El Ouidan) in Morocco, this being the first confirmed record of the species from North Africa. The morphology of these newly collected specimens agrees well with previous descriptions, but mitochondrial (Cox1 and 16S) and nuclear ITS (ITS1-5,8S-ITS2) molecular data lead to a discussion of a more complex general view concerning the number of species, synonyms and nomenclatural problems hidden behind the reports of Craspedacusta sowerbii. ResumenLa diversidad oculta en las identificaciones basadas en la morfología de especies invasoras de amplia distribución: el caso de la "bien conocida" hidromedusa Craspedacusta sowerbii Lankester 1880. El número relativamente escaso de características morfológicas utilizadas para delimitar especies estrechamente relacionadas y el panorama cada vez más preocupante en el que el cambio climático global provoca la rápida dispersión de especies exóticas invasoras pueden conducir a la difusión precipitada por todo el mundo de informes sobre una especie determinada. Craspedacusta sowerbii Lankester, 1880, que se considera la especie de medusa de agua dulce más extendida, ha sido observada en numerosos lugares en todos los continentes, excepto en la Antártida. Recientemente, se recogieron algunas medusas atribuidas a C. sowerbii en un embalse artificial (Bin El Ouidan) en Marruecos, que representaron el primer registro confirmado de la especie en el norte de África. La morfología de estos especímenes recién recolectados concuerda con las descripciones anteriores, pero los datos moleculares mitocondriales (Cox1 y 16S) y nucleares ITS (ITS1-5,8S-ITS2) suscitan un debate general más complejo con respecto al número de especies, las sinonimias y los problemas nomenclaturales ocultos tras los informes de Craspedacusta sowerbii.Hidden diversity under morphology-based identifications of widespread invasive species: the case of the 'well-known' hydromedusa Craspedacusta sowerbii Lankester 1880

Freshwater jellyfish in northern temperate lakes: Craspedacusta sowerbii in British Columbia, Canada

“…In agreement with Oualid et al (2019), 16S and ITS analyses showed at least 4 main Craspedacusta lineages. According to the identification provided by the different authors to the sequences used (Zhang et al 2009, Zou et al 2012), these species are C. sinensis (for the moment only reported from China), C. ziguiensis (only from China), and 2 separate widespread lineages mainly attributed to C. sowerbii (Collins et al 2008, Fritz et al 2009, Zhang et al 2009, Stefani et al 2010, Zou et al 2012, Karaouzas et al 2015, Failla Siquier et al 2017, Riyas & Kumar 2017, Fuentes et al 2019, Oualid et al 2019. The divergent Cox1 sequence MF000493 from Switzerland could be incorrect -perhaps a nuclear pseudogene, as the 16S sequence places it within one of the 2 main C. sowerbii clades (P. Schuchert pers.…”

“…Dejdar's anatomical and nematocyst information are from some medusae collected in Vltava (Moldau close to Libčice, Czech Republic). However, BC specimens of C. sowerbii are quite similar to those examined by Oualid et al (2019) from North Africa, but both sets of samples are, from a phylogenetic point of view (mitochondrial and nuclear markers), widely separated clades (Figs. 4,S1 & S2), sometimes separated by different Craspedacusta species (Fig.…”

“…DNA kit (OmegaBiotech) following the manufacturer's instructions. The Cox1 and 16S mito-chondrial regions as well as the nuclear internal transcribed spacer (ITS) region (ITS1-5, 8S-ITS2) were sequenced as proposed by previous authors (Fritz et al 2009, Karaouzas et al 2015, Oualid et al 2019) for comparative purposes. The Cox1 region was amplified using the primers dgLCO1490 5'-GGT CAA CAA ATC ATA AAG AYA TYG G-3' and dgHCO 2198 5'-TAA ACT TCA GGG TGA CCA AAR AAY CA-3' (Meyer et al 2005), while the 16S region was amplified using the primers 16S.Cunningham.…”

“…The set of new sequences were assembled with homo logous ones from GenBank of other Craspedacusta species. When available, sequences of the closest olindiid genera were used as an out-group in the implemented phylogenetic analyses (see relative phylogenetic placement of the genus Craspedacusta among other olindiids and other selected out-groups in Oualid et al 2019). The alignments of the different sets of sequences were carried out using MUS-CLE, as implemented in MEGA6 (Tamura et al 2013).…”

“…Thus, C. sowerbii can be considered a species complex -at least 2 distant genetic lineages with similar morphological features. A more complete sampling programme, detailed morphological descriptions, and genetic analyses are highly recommended for the C. sowerbii species complex, as also stressed by Oualid et al (2019). These further efforts should permit the better delineation of species (firstly by genetics), allowing differentiation among those morphological characters with reliable value in the delimitation of species, and future separate additional ecological and physiological investigations.…”