STUPENDIDAE, Kelly & Cárdenas, 2016

Kelly, Michelle & Cárdenas, Paco, 2016, An unprecedented new genus and family of Tetractinellida (Porifera, Demospongiae) from New Zealand’s Colville Ridge, with a new type of mitochondrial group I intron, Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) 177 (2), pp. 335-352 : 341-342

FAMILY STUPENDIDAE FAM. NOV.

Type species

Stupenda singularis gen. et sp. nov.

Diagnosis

Tetractinellida with s pherical growth form. Skeleton strictly radial with bundles of huge oxeas spiralling outwards from a centrum. Cortex thick and armoured with brushes of packed oxeas and orthotriaenes, the cladomes of which project beyond the surface. Orthotriaenes are huge with typically clubbed clads and a long conical rhabdome, the upper third of which is acanthose. Microscleres are contorted microspined sigmaspires.

Remarks

The partially acanthose clubbed orthotriaenes of this species are unprecedented in the Recent and fossil lit- erature in terms of their large size and morphology, and the single specimen and holotype displays characteristics of both tetillid and astrophorine taxa. Tetillid characters include a spherical external form, a strictly radiating skeleton with huge attenuated oxeas and triaenes spiralling from a siliceous centrum, and microspined sigmaspire microscleres. The long, robust orthotriaenes are reminiscent of the triaenes in the astrophorine family Ancorinidae but are unlike the frequently delicate hair-like pro- and anatriaenes typical of tetillid species. Finally, the orthotriaenes are acanthose with clubbed clads, two features that have not been recorded in any other triaene-bearing taxa except Yucatania sphaeroidocladus ( Hartman & Hubbard, 1999) (family Thrombidae Sollas, 1888 ). However, in this species the triaenes are very small by comparison ( Y. sphaeroidocladus acanthotriaene rhabdome length 248–480 μm, cladome width 10– 24 μm; S. singularis gen. et sp. nov. rhabdome length 2075–3075 μm, cladome width 140–240 μm) and the rhabdome and cladome are sparsely microspined along the entire length of the megasclere; in S. singularis gen. et sp. nov. the triaenes are acanthose only in the proximal third. Both Yucatania Gómez, 2006 and

† and the last 110 bp

‡ of the same intron and so they are merged here

COI, cytochrome c oxidase subunit I. CDS, coding sequence.

Thrombus Sollas, 1886 , also possess unique ‘trichotriaene’ microscleres in addition to unique minute pseudobirotulate rhabds; these are also microspined. Both taxa belong to the Thrombidae , currently considered to be in the suborder Astrophorina ( Uriz, 2002; Cárdenas et al., 2011). The astrophorine genus Acanthotriaena Vacelet, Vasseur & Lévi, 1976 (family Pachastrellidae Carter, 1875 ) has anatriaenes that are sparsely basally spined but these are very different from those of S. singularis gen. et sp. nov.

Stupendidae fam. nov. is monogeneric, forming a sister group to the desma-bearing Scleritodermidae / Siphonidiidae / Azoricidae in the 18S tree ( Fig. 2 ). Genetically however, these two sister groups seem quite distant: if we compare only the short V4–V5 region (494 bp) of S. singularis gen. et sp. nov. with, respectively, Leiodermatium lynceus Schmidt, 1870 (Azoricidae) , Scleritoderma sp. (Scleritodermidae) , and Siphonidium ramosum ( Schmidt, 1870) (Siphonidiidae) , we find 11– 15 bp differences. As a comparison, we find smaller genetic differences when we compare the same V4– V5 region between Neophrissospongia microstylifera ( Lévi & Lévi, 1983) (Corallistidae) and Theonella atlantica van Soest & Stentoft, 1988 (Theonellidae) (1 bp) or between Geodia barretti Bowerbank, 1858 (Geodiidae) and Pachastrella sp. (Pachastrellidae) (4 bp). In the morphological taxonomic sense Stupendidae fam. nov. and Scleritodermidae / Siphonidiidae / Azoricidae form a strongly supported and separate clade at the same taxonomic level as the astrophorine and tetillid clades. Based on morphology, we place this new family in the suborder Spirophorina because it possesses sigmaspires and triaene megascleres but molecular results may suggest otherwise (see Discussion).

Figures

Figure 2. Tetractinellida 18S rDNA maximum likelihood (ML) tree reconstructed with RAxML under the generalized time-reversible Gamma (GTRGAMMA) model: 89 sequences. At each key node, ML bootstrap supports (100 bootstrap replicates) and Bayesian posterior probabilities are given (only bootstrap supports above 50 are shown). GenBank accession numbers are given after each taxon name; when sequences have been merged, two accession numbers are given. ‘K94’ indicates that this is a short 18S sequence (V4–V5 region) from Kelly-Borges & Pomponi (1994) (accession numbers KT356876–KT356885).