Rossella podagrosa Kirkpatrick, 1907—A valid species after all

Abstract

In this study we provide evidence that the species Rossella podagrosa Kirkpatrick, 1907, commonly considered a synonym of Rossella racovitzae Topsent, 1901, is truly a valid species. We show that it can be clearly distinguished from other species especially when taking into consideration the in situ habitus of the sponge in combination with the spicules. Furthermore we demonstrate the weaknesses in the so far published synonymy concept for the very complicated genus Rossella Carter, 1872. From this we conclude that the best strategy for further analysis of Rossella and establishment of acceptable synonymies will need to be based on detailed examination of the spicules, the holotypes, and in situ habitus. When possible it will be useful to analyze specimens from all Antarctic oceanographic regions.

Macroscopic characteristics facilitate identification of common Antarctic glass sponges (Porifera, Hexactinellida, Rossellidae)

“…Contamination can be reduced or avoided by taking dermal spicule samples from the inner wall of the sponges and where it appears most intact. Table 1 Most relevant species descriptions consulted and material analyzed for this study (numbers refer to references) 1: Carter (1872), 2: Topsent (1901), 3: Kirkpatrick (1907), 4: Schulze and Kirkpatrick (1910), 5: Topsent (1916), 6: Burton (1929, 7: Barthel and Tendal (1994), 8: Teixidó et al (2006), 9: Göcke and Janussen (2013, 10: Göcke et al (2015)…”

“…There was no obvious pattern in the local and regional distribution of the different morphotypes. Rossella podagrosa, in contrast, has a distinct habitus which is very different from R. racovitzae: the body shape is mostly slender and elongate with a small osculum and without any conules (Göcke et al 2015). Its surface is rough and covered by a thin spicule veil which collects sediment and organic debris and gives the sponge a dirty appearance ( Fig.…”

“…Besides lacking clarity or comprehensiveness in species descriptions, the complicated taxonomic history of the genus Rossella adds further problems. About 25 species and varieties have been described (Reiswig 1990), followed by numerous synonymizations and revisions (for a summary see Göcke et al 2015). In the latest taxonomic revision of Antarctic Rossellidae, Barthel and Tendal (1994) recognized seven species of Rossella: R. antarctica, R. fibulata, R.…”

“…By contrast, R. racovitzae is considered highly variable regarding its external morphology and spicules and was suggested to include several cryptic species (Barthel and Tendal 1994;Göcke and Janussen 2013). Indeed, the species R. podagrosa, which has long been synonymized with R. racovitzae and considered a strongly budding morphotype of the latter, has recently been re-described and re-established as a valid species based on material from the Ross Sea (Göcke et al 2015). Although this has reduced the morphological variability of R. racovitzae, the species is still poorly defined and shows similarities to R. villosa and R. levis (Barthel and Tendal 1994;Göcke and Janussen 2013).…”

Benthic responses to an Antarctic regime shift: food particle size and recruitment biology

“…The data for those species that were confounded in 1968 with their 2010 species designations are presented in Table 2. The most important sponge species, Rossella podagrosa, was misidentified as R. racovitzae in 1968 (Gocke et al 2015). This is the most abundant sponge in the area, but because the individuals within patches were indistinguishable and often partially buried, the 1968 black and white photographs were inadequate and overestimated their percent cover.…”