An overview on the freshwater sponge fauna (Demospongiae: Spongillida) of New Zealand and New Caledonia with new insights into Heterorotula from deep thermal vents of the Lake Taupo

ABSTRACT

Data on the freshwater sponge fauna of New Caledonia and New Zealand (5 species, 3 genera, and 2 families) of the order Spongillida (Porifera, Demospongiae) is reported in the framework of an assessment of Australasian biodiversity. Literature screening and a comparative study by LM and SEM of these poorly known taxa on the basis of historical and recent materials delineated the compositions of local spongillofauna. Pachyrotula raceki, Oncosclera diahoti and Heterorotula caledonensis are endemic to New Caledonia, as is the monospecific genus Pachyrotula. New Caledonia shares Heterorotula multidentata with Eastern Australia. The endemic Heterorotula kakahuensis is known from New Zealand. Results highlighted (a) the problematic status of Oncosclera diahoti; (b) the congeneric divergence/convergence of traits among closely related genera, i.e. Heterorotula and Ephydatia, and yielded (c) the discovery in BMNH material of a New Zealand Spongillida, sharing some morphotraits with the genus Pottsiela never recorded before in Australasia. Further integrated molecular, morphological and biogeographical analyses will clarify the tangled phylogenetic and evolutionary history of Australasian and Gondwanan lineages of Spongillida.

KEYWORDS:

• Australasian Bioregion
• Pacific archipelagos
• freshwater biodiversity
• Porifera checklist
• type materials
• morphotraits (SEM)
• biogeographic patterns
• Gondwanan tracks

Acknowledgements

We are very grateful to the Tuwharetoa Maori Trust Board for granting us permission to study the fauna of the Horomatangi Reefs area. We kindly acknowledge Cornel de Ronde (Institute of Geological and Nuclear Science, Lower Hutt, New Zealand) project leader of the joint New Zealand–Germany ‘Taupo ’98ʹ dive project, Karen Hissman, Jago dive coordinator (Max Planck Institute for Behavioural Physiology, Seewiesen, Germany) and Belinda Alvarez de Glasby (Lund University, Sweden) for making available such interesting material. Our thanks to Klaus Rützler of National Museum of Natural History, Smithsonian Institution, Washington D.C., USA; Cecilia Volkmer-Ribeiro of Museu Nacional do Rio de Janeiro, Brazil; Clare Valentine of The Natural History Museum, London, United Kingdom; and Rob van Soest of RMNH, Nationaal Natuurhistorisch Museum, Leiden. This paper was supported by the University of Genoa (Italy), Fondazione di Sardegna (FS–2016), Regione Autonoma Sardegna (RAS 2016-L.R. 7/2007 e RAS2012-L.R.7/2007-CRP60215) and Italian MIUR-PRIN.

Disclosure statement

No potential conflict of interest was reported by the authors.