Detection of a newClytiaspecies (Cnidaria: Hydrozoa: Campanulariidae) with DNA barcoding and life cycle analyses

Abstract

The genus Clytia is distributed worldwide, but most accepted species in this genus have been examined either only at the hydroid or medusa stage. The challenge in identifying Clytia species reflects their complex life cycles and phenotypic plasticity. In this study, molecular and morphological investigations of Clytia specimens from the coastal waters of China revealed an as yet unreported species, designated C. xiamenensis sp. nov., that was considered as conspecific to two nearly cosmopolitan species, C. hemisphaerica and C. gracilis. DNA barcoding based on partial mitochondrial cytochrome c oxidase subunit I (COI) and large subunit ribosomal RNA gene (16S) confirmed the highly distinct lineage of C. xiamenensis sp. nov. These results were corroborated by the detailed observations of its mature medusae and its colonies, which showed that C. xiamenensis sp. nov. was morphologically distinct from other species of Clytia. Thus, based on our findings, the nearly cosmopolitan distribution attributed to some species of Clytia might rather be due to the misidentification, and it is necessary to elucidate their whole life cycle in order to establish the systematic validity of all species within the genus Clytia.

Reassessment of Morphological Diagnostic Characters and Species Boundaries Requires Taxonomical Changes for the Genus Orthopyxis L. Agassiz, 1862 (Campanulariidae, Hydrozoa) and Some Related Campanulariids

“…Formal taxonomical studies of this family are relatively rare and mainly address the evolution of the medusa [14,15,16,17] and the delimitation of genera and species [7,18,19,20,21,22,23,24,25]. There has been a clear discordance regarding the diagnostic morphological characters used in the taxonomy of this group [19,26,27,28,29,30,31], mostly because the majority of these species have simple and similar morphologies that can be quite variable cf.…”

Morphology and molecular analyses of a newClytiaspecies (Cnidaria: Hydrozoa: Campanulariidae) from the East China Sea

“…The life cycle of Clytia comprises a free swimming medusae stage and a sessile hydroid stage. Medusae of Clytia are frequently found in surface coastal waters, while hydroids of this genus are common in shallow-water benthic communities (Cornelius, 1995; Madin et al , 1996; Boero et al , 2005; Lindner et al , 2011; Zhou et al , 2013). With growing attention focused on the ecological impact of jellyfish blooms, these tiny organisms are emerging as an important competitor and predators in the coastal marine ecosystem (Lucas et al , 1995; Bouillon et al , 2006; Gravili et al , 2008; Miglietta et al , 2008).…”

“…However, species diagnosis in Clytia is challenging. Firstly, most species are based either on the hydroid (42 species) or the medusae form (30 species), with only 11 species having had their complete life cycle investigated 1 (Mayer, 1910; Roosen-Runge, 1970; West & Renshaw, 1970; Kubota, 1978a, b; Cornelius, 1995; Pagliara et al , 2000; Lindner & Migotto, 2002; Gravili et al , 2008; Lindner et al , 2011; Zhou et al , 2013). Secondly, diagnostic characters of some species in the genus were based on a single specimen, or sometimes even on an immature animal, e.g.…”

“…Thirdly, characters long thought to have taxonomic values tend to be variable between individuals of the same population, at least in certain species (Kubota, 1978a; Bouillon & Boero, 2000). Finally, with the emerging of molecular techniques, cryptic species or even new species are being revealed (Lindner et al , 2011; Zhou et al , 2013).…”

“…DNA barcoding based on mitochondrial COI proved to be a useful molecular tool to identify species efficiently and reliably among many animal taxa (Hebert et al , 2003a, b; Bucklin et al , 2010a, b, 2011; Ortman et al , 2010). In the genus Clytia , COI was also applied to identify ambiguous specimens (Laakmann & Holst, 2014) and detect cryptic or new species (Lindner et al , 2011; Zhou et al , 2013). Recently, mitochondrial 16S was proposed as a candidate for hydrozoa barcoding (Moura et al , 2008; Zheng et al , 2014).…”