Search results for "Oswaldella"
showing 8 items of 8 documents
On several species of Oswaldella Stechow, 1919 (Cnidaria, Hydrozoa), including the description of a new species
2018
Oswaldella is the most speciose genus of Antarctic hydroids, being one of the most characteristic genera of hydrozoans of the Antarctic benthic marine ecosystem. A relatively high number of taxonomic characters allow species identification, but some key ones are difficult to study properly with a light microscope. In order to improve knowledge of species of the genus, a SEM survey of five of the 27 known nominal species of Oswaldella was carried out, including type material of O. grandis and O. terranovae. The study has revealed no significant differences between O. stepanjantsae and O. terranovae and, consequently, the former is considered a junior synonym of the latter. The type material …
Species of Oswaldella Stechow, 1919 (Cnidaria, Hydrozoa) from recent antarctic expeditions with R.V. 'Polarstern', with the description of eight new …
1997
Twelve species of the genusOswaldellaStechow have been studied, eight of which are new to science [Oswaldella delicatasp. nov.,O. encarnaesp. nov.,O. garciacarrascosaisp. nov.,O. gracilissp. nov.,O. grandissp. nov.,O. incognitasp. nov.,O. obscurasp. nov.andO. rigidasp. nov.], originating from the Weddell Sea and collected by several antarctic expeditions with R.V.Polarstern. Each is described and figured, its systematic position is considered and current data concerning its autecology and geographical distribution are given. Finally, a comparative table is presented including the principal features of all known species of the genus.
Breaking molds: Oswaldella laertesi, sp. nov., a unique Antarctic species of Oswaldella Stechow, 1919 (Cnidaria: Hydrozoa: Kirchenpaueriidae)
2007
A new species of the Antarctic genus Oswaldella Stechow is described and figured, and its position amongst the remaining species of the genus is discussed. The material was collected from the Ross Sea area (Antarctica) during the BioRoss survey of the western Ross Sea and Balleny Islands in 2004. Oswaldella laertesi, sp. nov., is unique amongst known species of the genus in having hydrocladia arranged in three longitudinal rows.
<p><strong>SEM study of species of <em>Oswaldella</em> Stechow, 1919 (Cnidaria, Hydrozoa, </strong><br /><stro…
2015
Oswaldella is the most speciose genus, and one of the most characteristic, of hydrozoans inhabiting the Antarctic benthic marine ecosystem. Its species have relatively many important taxonomic characters allowing for their identification. Some of them, however, are difficult to study properly with a compound microscope. With the aim of improving scientific knowledge concerning species of the genus, a SEM survey of species of Oswaldella was carried out to study key morphological characters. Fourteen out of the 27 known nominal species were considered. The study has revealed unknown important characters, such as the presence of nematothecae associated with the nematophores at the cauline apop…
On two new species of Oswaldella Stechow, 1919 (Cnidaria, Hydrozoa) from Bransfield Strait (Antarctica)
1998
Two species of the genus Oswaldella Stechow, 1919 new to science (Oswaldella crassa sp. nov. and O.␣curiosa sp. nov.) were studied. Both species are described and figured; their systematic position amongst the remaining species of the genus is discussed. The material originates from the Bransfield Strait area (Antarctica) and was collected during the United States Antarctic Research Program with R.V. Eltanin. A comparative table listing the main features of the known species of Oswaldella is presented. Finally, a general survey of geographical and bathymetrical distribution of the known species of Oswaldella is given.
Phylogenetic analysis of the Antarctic genus Oswaldella Stechow, 1919 (Hydrozoa, Leptomedusae, Kirchenpaueriidae)
1999
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…
Estudio, mendiante electroscopía electrónica de barrido, de 16 especies del género Oswaldella Stechow, 1919 (Cnidaria: Hidrozoa)
2013
El género Oswaldella Stechow (1919) es el género de hidrozoos antárticos más diverso y uno de los géneros de invertebrados más abundante de los fondos oceánicos del sur de nuestro planeta. En este estudio se emplea la microscopía electrónica de barrido (MEB) para detallar numerosas características morfológicas de este género hasta ahora poco conocidas. En concreto, el número de nematotecas axilares, la forma de las nematotecas caulinares y de las hidrotecas adquieren un nuevo significado a través de este instrumento. En concreto, observamos que estas caracteríticas morfológicas parece variar mucho más de lo que en anteriores estudios con microscopía óptica se había observado. Se hace, ademá…
Benthic hydroids associated with volcanic structures from Bransfield Strait (Antarctica) collected by the Spanish Antarctic expedition GEBRAP96
2006
During the Spanish Antarctic expedition GEBRAP96 a survey to study the benthic fauna associated with deep volcanic structures in the Bransfield Strait was carried out. Amongst the benthic samples, a small collection of hydroids was gathered. A total of 10 species, most of them Leptothecata, was recorded; only two species of anthoathecates were present. Kirchenpaueriidae and Sertulariidae were the dominant families, and Symplectoscyphus and Oswaldella the predominant genera. Oswaldella niobae sp. nov. is described and figured. Since samples were taken at great depth, the lowest limit of the bathymetrical distribution for several species is distinctly increased. None of the samples showed sig…