A new carnivorous shallow-water sponge from McMurdo Sound, Antarctica (Porifera, Poecilosclerida)
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ORIGINAL PAPER
A new carnivorous shallow-water sponge from McMurdo Sound, Antarctica (Porifera, Poecilosclerida) Rob W. M. van Soest & Bill J. Baker
Received: 18 August 2010 / Revised: 4 October 2010 / Accepted: 12 November 2010 / Published online: 1 December 2010 # The Author(s) 2010. This article is published with open access at Springerlink.com
Abstract A new shallow-water representative of the carnviorous sponge genus Asbestopluma is described from the southernmost Antarctic region of McMurdo Sound. Asbestopluma (Asbestopluma) vaceleti n.sp. is a white, thin, sparingly branched sponge fringed by filaments along its entire length, with a slight thickening at the top of the branches. It was collected at 30 m depth by SCUBA divers from under densely populated overhangs of rocky substrata. The new species stands out among Antarctic Asbestopluma by the possession of forceps microscleres, a feature shared with several species from Arctic–Boreal waters (bathyal to deep-sea) and one from the Kermadec Trench (deep sea), but not previously reported from Antarctic species. A unique trait of the new species distinguishing it from all forceps-bearing Asbestopluma is a second category of reduced anisochelae. The new species is most similar to A. hypogea, a shallow-water cave species from the Mediterranean, which differs in having a smooth stalk and a filament-bearing ovoid body. A comparison is made with descriptions of Antarctic Asbestopluma species and all species possessing forceps microscleres. Keywords Antarctica . Carnivorous sponge . Asbestopluma . New species
R. W. M. van Soest (*) Zoölogisch Museum Amsterdam, Netherlands Centre for Biodiversity, P.O. Box 94766, 1090 GT, Amsterdam, the Netherlands e-mail: [email protected] B. J. Baker Department of Chemistry, University of South Florida, Tampa, FL 33620, USA e-mail: [email protected]
Introduction Carnivorous sponges, family Cladorhizidae, are unique in the phylum Porifera in possessing a combination of skeletal and organic tissue properties allowing them to catch small prey animals such as copepods and cladocerans (Vacelet and Boury-Esnault 1995). With the exception of the genus Chondrocladia Thomson (1873), the sponges of this family lack an aquiferous system. The overwhelming majority of carnivorous sponges occur in deep sea soft bottom habitats, and their deviating feeding strategy and accompanying physical features are explained as an adaptation to paucity of filter feeding biomass in oligotrophic deep sea habitats. The carnivorous feeding strategy was first detected in Asbestopluma hypogea Vacelet and Boury-Esnault (1996), which in contrast to most other cladorhizids lives in a shallow-water rocky habitat (caves near Marseille). Nevertheless, this habitat is considered similarly oligotroph and considered a displaced deep sea environment allowing the colonization of deep sea specialist sponges. Recently, SCUBA exploration of Antarctic rocky habitats near McMurdo Sound, yielded approximately 45 species of sponges (B. Baker, personsal communication). Among the
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