Glaciambulata neumayeri gen. et sp. nov., a new Antarctic trachymedusa (Cnidaria: Hydrozoa), with a revision of the family Ptychogastriidae

Abstract

Abstract.A new genus and species of sympagic trachymedusa, Glaciambulata neumayeri gen. et sp. nov., are described based on material from Antarctica. Its generic features are compared to those of its relatives, Ptychogastria Allman, 1878 and Tesserogastria Beyer, 1959, and a review of the family Ptychogastriidae Mayer, 1910, based on literature data, is provided. From this, it results that the poorlyknown Pectis antarctica Haeckel, 1879, formerly assigned to Ptychogastria by a number of authors, displays all characters of the contemporary rhopalonematid genus Voragonema Naumov, 1971. It is additionally demonstrated that V. laciniata Bouillon et al., 2001 is coterminous with P. antarctica, a finding that clarifies, 137 years later, the morphology and the taxonomic status of Haeckel's medusa. In accordance with the Principle of Priority, Pectis is recognized as the valid name of the genus, and Voragonema is assigned to its synonymy. Similarly so, the specific name introduced by Haeckel has priority over laciniata.

The illusion of rarity in an epibenthic jellyfish: facts and artefacts in the distribution of Tesserogastria musculosa (Hydrozoa, Ptychogastriidae)

“…The number and position of the statocysts are diagnostic characters separating Tesserogastria from all other genera in family Ptychogastriidae [12,21]. However, some confusion exists regarding the exact position of these structures in T. musculosa, as they have been alternatively described in scientific accounts as adradial [6] or interradial [12].…”

“…However, some confusion exists regarding the exact position of these structures in T. musculosa, as they have been alternatively described in scientific accounts as adradial [6] or interradial [12]. The original description of the species does not include information on the position and number of statocysts because Beyer was unable to find any in formalin-preserved animals, presumably due to the disintegration of the statoliths in this fixative [4].…”

“…After collection, the medusae were brought to the laboratory and identified to species level with the aid of specialized literature [4,12]. Specimens were then fixed either in 4% formalin (for morphological analysis) or 96% ethanol (for DNA barcoding), with the latter group of specimens photographically documented prior to fixation.…”

“…The population assessment of benthic ptychogastriid medusae has only recently become feasible thanks to improved sampling techniques and in situ observations by divers or ROVs, resulting in the description of new species and several new records for the already-known ones [3,12]. Other multidisciplinary approaches (e.g.…”

“…Although the paper by Beyer was actually published in 1958, some authors have mistaken the date of this publication as 1959 [2, 12,21] probably based on a series of copies of Vol. 6 of the Nytt Magasin for Zoology printed in that year.…”