Porifera source details

SourceID	164848
Name	Van Soest, R.; Carballo, J.L.; Hooper, J. 2012. Polyaxone monaxonids: revision of raspailiid sponges with polyactine megascleres (Cyamon and Trikentrion). Zookeys 239: 1-70.
Type	Publication
Link	http://dx.doi.org/10.3897/zookeys.239.3734
Full text	Available for editors   [request]
Abstract	Among the thousands of non-tetractinellid (monaxonid) Demospongiae species, less than twenty possess polyactine (usually three- or four-claded) megascleres. These are currently assigned to two closely related genera, viz. Cyamon Gray and Trikentrion Ehlers, both members of the raspailiid subfamily Cyamoninae. The two genera are considered valid on account of differences in the shape and the ornamentation of the polyaxone spicules. Cyamon predominantly has four-claded equiangular spicules with all cladi spined or rugose, whereas Trikentrion usually has a majority of three-claded spicules on which spines are found only on a single basal clade. Nevertheless, the differences between the two genera appear to overlap in several known and newly discovered species, necessitating a revision of the two groups. Two new species of Cyamon were found to occur on inshore sandstone platforms off the coast of Mauritania. One of the new species, Cyamon amphipolyactinum sp. n., possesses unique small ‘double’ polyactine spicules in addition to the usual calthrops-like polyactine megascleres characteristic for Cyamon. The second new species, Cyamon arguinense sp. n., possesses polyactine megascleres of which only one of the cladi is spined the remaining three or more cladi being smooth, a feature that is considered characteristic of sponges of the genus Trikentrion. The type species of Cyamon, C. vickersii (Bowerbank) appears to have been misinterpreted as a Caribbean species, because circumstantial evidence strongly indicates an Indian Ocean origin. This has the consequence that specimens recorded subsequently under the name C. vickersii from various Western Atlantic localities are reassigned to Cyamon agnani (Boury-Esnault), a species originally described from Brazil. A new species, reported as Cyamon vickersii sensu Burton & Rao from the east coast of India, and available to us only as a single thick section mounted on a glass slide, is named Cyamon hamatum sp. n. The Cyamon membership of the only deep-sea species, Cyamon spinispinosum (Topsent) is drawn in doubt due to considerable morphological deviation from mainstream Cyamon. The type species of Trikentrion, T. muricatum (Pallas), is extensively described and discussed, and a neotype is assigned. West African Trikentrion laeve (Carter) is for the first time since its original description properly redescribed from the type material. The specimen recorded by Burton as Trikentrion laeve from Congo turned out to be different from the original material of Carter and is assigned to a new species, Trikentrion africanum sp. n. All species of both genera considered valid are reviewed, mostly based on the examination of type or other original specimens. Our revision shows the existence of twelve species of Cyamon and six species of Trikentrion. A key to the species is provided and remarks on the geographic distribution of both genera are made. Based on our study, the differences between Cyamon and Trikentrion are re-evaluated. Only one character absolutely distinguishes the two genera, the presence (Trikentrion) or absence (Cyamon) of trichodragmata. A further discriminating character is the possession of short thick styles (most Cyamon species) versus thick oxeas (many Trikentrion), but this is complicated by absence of the oxeas in three Trikentrion species. Although spination of the polyactine spicules in itself cannot serve to distinguish the two genera with certainty, those of Trikentrion are usually recognizable by excessive hook-like spines against a finer spination in Cyamon. Possibly, the polyactine spicules of both groups are non-homologous, with Cyamon polyactines derived from styles and Trikentrion polyactines from oxeas, but this remains to be further investigated.
Bibliographical term	Systematics, Taxonomy
Taxonomic term	Porifera
Taxa (26)	Cyamon Gray, 1867 (basis of record) Cyamon agnani (Boury-Esnault, 1973) (redescription) Cyamon amphipolyactinum Van Soest, Carballo & Hooper, 2012 (original description) Cyamon argon Dickinson, 1945 (basis of record) Cyamon arguinense Van Soest, Carballo & Hooper, 2012 (original description) Cyamon aruense Hentschel, 1912 (basis of record) Cyamon catalina Sim & Bakus, 1986 accepted as Trikentrion catalina (Sim & Bakus, 1986) (basis of record) Cyamon hamatum Van Soest, Carballo & Hooper, 2012 (original description) Cyamon koltuni Sim & Bakus, 1986 (basis of record) Cyamon neon de Laubenfels, 1930 (basis of record) Cyamon quadriradiatum (Carter, 1880) (basis of record) Cyamon quinqueradiatum (Carter, 1880) (basis of record) Cyamon spinispinosum (Topsent, 1904) (basis of record) Cyamon vickersii (Bowerbank, 1864) (basis of record) Cyamoninae Hooper, 2002 (additional source) Plectronella Sollas, 1879 accepted as Trikentrion Ehlers, 1870 (basis of record) Plectronella papillosa Sollas, 1879 accepted as Trikentrion muricatum (Pallas, 1766) (basis of record) Timea agnani Boury-Esnault, 1973 accepted as Cyamon agnani (Boury-Esnault, 1973) (redescription) Trikentrion Ehlers, 1870 (basis of record) Trikentrion africanum Van Soest, Carballo & Hooper, 2012 (original description) Trikentrion catalina (Sim & Bakus, 1986) (basis of record) Trikentrion flabelliforme Hentschel, 1912 (basis of record) Trikentrion helium Dickinson, 1945 (basis of record) Trikentrion laeve Carter, 1879 (basis of record) Trikentrion muricatum (Pallas, 1766) (basis of record) Trikentrion wickersi (Bowerbank, 1864) accepted as Cyamon agnani (Boury-Esnault, 1973) (taxonomy source)
Distributions (12)	Carolinian for Cyamon agnani (Boury-Esnault, 1973) Cortezian for Cyamon koltuni Sim & Bakus, 1986 Greater Antilles for Cyamon agnani (Boury-Esnault, 1973) Gulf of Guinea Central for Trikentrion muricatum (Pallas, 1766) Gulf of Guinea South for Trikentrion africanum Van Soest, Carballo & Hooper, 2012 Lesser Sunda for Trikentrion flabelliforme Hentschel, 1912 Mexican part of the North Pacific Ocean for Cyamon koltuni Sim & Bakus, 1986 Sahelian Upwelling for Cyamon amphipolyactinum Van Soest, Carballo & Hooper, 2012 Sahelian Upwelling for Cyamon arguinense Van Soest, Carballo & Hooper, 2012 Southern California Bight for Trikentrion helium Dickinson, 1945 Southern Norway for Cyamon spinispinosum (Topsent, 1904) Western India for Cyamon hamatum Van Soest, Carballo & Hooper, 2012
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