Areas of endemism in the Antarctic - a case study of the benthic hydrozoan genusOswaldella(Cnidaria, Kirchenpaueriidae)
Aim The aim of this study is to investigate areas of endemism within the distribution of Oswaldella species in the Southern Ocean, thereby testing previous hypotheses and proposing alternative scenarios for Antarctic evolution. Location Southern Ocean, Antarctic and sub-Antarctic waters of southern South America. Methods We prepared a database for the 31 currently known species of the Antarctic genus Oswaldella, which includes geographical locations gathered from published taxonomic studies as well as materials from museums and expeditions. A parsimony analysis of endemicity (PAE) was used to test hypotheses of distribution patterns. Results Four areas of endemism are hypothesized: southern…
Towards a phylogenetic classification of Leptothecata (Cnidaria, Hydrozoa)
AbstractLeptothecata are hydrozoans whose hydranths are covered by perisarc and gonophores and whose medusae bear gonads on their radial canals. They develop complex polypoid colonies and exhibit considerable morphological variation among species with respect to growth, defensive structures and mode of development. For instance, several lineages within this order have lost the medusa stage. Depending on the author, traditional taxonomy in hydrozoans may be either polyp- or medusa-oriented. Therefore, the absence of the latter stage in some lineages may lead to very different classification schemes. Molecular data have proved useful in elucidating this taxonomic challenge. We analyzed a supe…
Revision ofHalisiphoniaAllman, 1888 (Cnidaria, Hydrozoa, Hebellidae), with comments on its taxonomic position
The deep‐water genus Halisiphonia is reviewed, based on redescriptions of all available type specimens of its species. The genus includes four valid species, H. arctica, H. galatheae, H. megalotheca, and H. nana, and one species inquirenda, H. spongicola, for which the type could not be located.
Redescription of Bedotella armata from Biscay Bay, northern Spain, the type species of Bedotella Stechow, 1913 (Cnidaria, Hydrozoa, Lafoeidae), with comments on its taxonomic position
The circalittoral and bathyal genus Bedotella, comprising a unique known species endemic to the North European Atlantic (Lusitanian Province), Bedotella armata (Pictet, C. & M. Bedot, 1900) is redescribed based on a specimen from the Bay of Biscay, North Spain. As the holotype of the species, originally described as Campanularia armata, is sterile and incomplete, the present re-description includes new data concerning its morphometry, including gonothecae, and cnidom, as well as all the literature. The diagnostic characters of Bedotella armata are the presence of globular nematothecae, the campanuliform hydrothecae, and flabelliform, gigantic gonothecae. We corroborate the hypotheses of aff…
An overview of the phylogeny of the families Lafoeidae and Hebellidae (Hydrozoa:Leptothecata): their composition and classification
A cladistic analysis of the genera of the family ‘Lafoeidae’ was performed in order to investigate suprageneric classifications and the boundaries of the family, as well as to organise the available morphological data and discuss the possible evolution of some morphological characters. Our results suggest that the former ‘Lafoeidae’ must be separated into two families: the Hebellidae and the Lafoeidae (including the subfamilies Lafoeinae and Zygophylacinae).
Revision of the genus Filellum Hincks, 1868 (Lafoeidae, Leptothecata, Hydrozoa)
A taxonomic review of the cosmopolitan genus Filellum was performed considering morphology, morphometry and cnidome. Species for which we had access to materials were redescribed and morphologically characterized based on optical and scanning electron microscopy (SEM). The materials examined belong to museum collections, including type specimens. All records found in the literature were checked. Our analyses confirmed the validity of 10 out of the 18 nominal species referred to the genus, and established four others (F. adnatum, F. bouvieri, F. contortum and F. plicatum) as species inquirenda. A new species, Filellum bouvetensis sp. nov., is described. The species Reticularia annulata Watso…
Phylogenetic analysis of the Antarctic genus Oswaldella Stechow, 1919 (Hydrozoa, Leptomedusae, Kirchenpaueriidae)
A cladistic study was carried out on known species of the characteristically Antarctic genus Oswaldella, adopting as out-groups some other genera included in the family Kirchenpaueriidae. The analysis resulted in a cladogram with low CI in which no relationship between genera can be depicted. However, the hypothesis of monophyly of the genus Oswaldella is corroborated, being supported in our cladogram by five synapomorphies (although all are homoplastic with other taxa or reversed within the species of the genus). The basal relationships of the genus are uncertain, but three species groups are distinguishable within Oswaldella: 1) the O. incognita group, 2) the O. Antarctica group, and 3) a…
Mediterranean species of Eudendrium Ehrenberg, 1834 (Hydrozoa, Anthomedusae, Eudendriidae) with the description of a new species
A new species of Eudendrium from the Chafarinas Islands (south-western Mediterranean) is described. The distinctive character of this species is its association with symbiotic zooxanthellae, a feature in common with Myrionema, the only other genus of the family Eudendriidae. The evolutionary implications of this similarity are discussed. A review of the Mediterranean species of Eudendriidae is presented, including data on the cnidome when available, biological data from the material studied, and a key to identify the Mediterranean species.
Revision of the genusAcryptolariaNorman, 1875 (Cnidaria, Hydrozoa, Lafoeidae)
The genus Acryptolaria is reviewed, with a complete redescription of the type specimens, with the exception of A. andersoni and A. rectangularis for which type material could not be located. The genus includes 16 valid species, though A. andersoni is insufficiently known. All records found in the literature have been checked. The cnidome proved to be a useful tool for species identification. A key for the identification of the species of the genus is also presented.
Redescription and systematic status of the Antarctic genusAbietinellaLevinsen, 1913 (Lafoeidae, Hydrozoa, Cnidaria)
The Antarctic–Patagonian genus Abietinella, comprising two known species, Abietinella operculata (Jaderholm, 1903) and Abietinella grandis (Vanhoffen, 1910), is reviewed. The holotype of Abietinella operculata is fully redescribed, including morphometry and cnidome, unknown up to now. Its distinctive characters are the growth habit, hydrothecal shape and, most important, the presence of a dish‐shaped operculum attached to the adcauline side of the hydrothecal aperture. We corroborate its conspecificity with A. grandis and, therefore, the monotypic condition of Abietinella.
Revision of the genusCryptolarellaStechow, 1913 (Lafoeidae, Leptothecata, Hydrozoa)
The bathyal genus Cryptolarella, comprising three known species, Cryptolarella abyssicola (Allman, 1888), Cryptolarella diffusa (Allman, 1888) and Cryptolarella humilis (Allman, 1888), is reviewed after the study of the holotypes of the species. A complete redescription and characterization of the species, including new data concerning morphometry and cnidome is presented, and its literature data reviewed. We conclude that all species are conspecific, resulting in a single valid species, C. abyssicola. The distinctive characters of the species are the growth habit, gonothecal arrangement and cnidome.
Southern Ocean areas of endemism: a reanalysis using benthic hydroids (Cnidaria, Hydrozoa)
The biogeographic history of the Southern Ocean (SO) fauna is complex and poorly studied, especially the areas of endemism. We reanalyzed the data of Marques & Peña Cantero (2010), along with other geographical records of endemic benthic hydroids below 45°S. A Parsimony Analysis of Endemicity (PAE) based on 5° latitude by 5° longitude matrix with 61 species resulted in eight areas of endemism. We discuss these results in the context of different hypotheses of the evolution of the SO fauna and previously proposed biogeography patterns.