Stellettinopsis Carter

Kelly, Michelle & Sim-Smith, Carina, 2012, A review of Ancorina, Stryphnus, and Ecionemia (Demospongiae, Astrophorida, Ancorinidae), with descriptions of new species from New Zealand waters, Zootaxa 3480, pp. 1-47 : 31

Genus Stellettinopsis Carter

Stellettinopsis Carter, 1879: 348 .

Type species: Stellettinopsis corticata Carter, 1879: 348 .

Diagnosis. Massive, cushion-shaped, bulbous or thickly encrusting Ancorinidae , with oxeas packed obliquely or paratangentially in the choanosome. The ectosome is well developed and defined by bouquets of subdermal oxeas and triaenes, when present, emerging from the choanosome, in between which are large aquiferous canals. Euasters form a concentration below and throughout a crust of long microrhabds at the surface, and oxeas protrude through the surface, rendering it hispid and rough to the touch. Megascleres include medium-sized oxeas in 1 to 2 size categories with common stylote modifications, and relatively short triaenes of different types including dichotriaenes, plagiotriaenes, orthotriaenes, and rarely anatriaenes. Triaenes are frequently very rare. Microscleres include relatively long strongylote or hastate acanthomicrorhabds that form a crust at the surface of the sponge, under which is a concentration of small tylasters, chiasters, and oxyasters, and rarely anthasters in 1 to 2 size categories.

Remarks. We are confident in this proposal to resurrect Stellettinopsis without recourse to examination of the relevant material because the published descriptions of species are clear and definitive, particularly those in the later contributions by van Soest & Beglinger (2008) and Cárdenas et al. (2009) (Table 3). The species conform to a general form of sponge that shares a unique combination of the characters seen in Ecionemia (possession of uniform ectosomal microrhabds), Ancorina (bouquets of megascleres in the ectosome, second category of oxyasters in choanosome), and Stryphnus (megascleres in paratangential arrangement in the choanosome, second category of choanosomal oxyasters, and variable presence of triaenes) in particular. Species considered to be valid include Stellettinopsis corticata (type species), S. fenimorea , S. megastylifera , S. solida , S. cherbonnieri , and S. laviniensis .

Stellettinopsis (and Stryphnus ) species that appear to lack triaenes because of their rarity, bear a superficial resemblance to Melophlus (see van Soest & Beglinger 2008) and Asteropus (see Cárdenas et al. 2009 on Stryphnus ), genera which lack triaenes completely. However, species of Melophlus have a tangential layer of microrhabds in three size categories in the ectosome, and species of Asteropus have a tangential layer of large choanosomal oxeas.

It is interesting to briefly consider the biogeographic distribution of the genera Ancorina , Ecionemia , Stryphnus and Stellettinopsis ( Fig. 8 , see also Table 3). The greatest number of species (14) are found in the Western Indian Ocean, from the eastern coast of South Africa north to the Red Sea, with Ecionemia species extending east across the Indo-Pacific, down to warm temperate northern New Zealand, into the tropical west central Atlantic ( E. demera ) and across to West Africa ( E. nigra ). A further 14 species of Stryphnus and Ancorina are found in the cold southern waters off New Zealand. Five species of Stryphnus and Ancorina are found in the northeast Atlantic and Mediteranean, but only two species of Stryphnus are found in the tropical west central Atlantic with two species of Stellettinopsis . Thus, Ecionemia and Stellettinopsis are generally warm temperate–tropical species, Ancorina is a warm to cold temperate species, and Stryphnus is predominantly a cold to cool temperate water species.

Figures

FIGURE 8. Global distribution of Stryphnus, Ancorina, Ecionemia and Stellettinopsis species. Inset = distribution around New Zealand.