PMC

Species names are given according to the PhyloCode (Article 21.5). Bootstrap nodal support values of clades defined by the PhyloCode are given (2,000 replicates). For the color-codes of the Astrophorida families sensu Systema Porifera, see .

Bootstrap nodal support values >50 are given at the nodes (2,000 replicates). Species names (according to the Linnaean classification) and sampling localities are given in . Names established under the PhyloCode are in italics and identified with the symbol ‘p’.

The ML reconstructions of the ancestral conditions at the nodes were estimated using Mesquite 2.74. For the readers' convenience, species clades have been reduced to one sample (except in cases of para- or polyphyletic species). Species names in blue represent deep-water species. Species names in black represent shallow-water species. For the color-codes of the Astrophorida families sensu Systema Porifera, see .

The ML reconstructions of the ancestral conditions at the nodes were estimated using Mesquite 2.74. For the readers' convenience, species clades have been reduced to one sample (except in cases of para- or polyphyletic species). Species names in blue represent deep-water species. Species names in black represent shallow-water species. For the color-codes of the Astrophorida families sensu Systema Porifera, see .

(a–d) A few Astrophorida species. (a): Geodia phlegraei (Geodiidae) collected in the Denmark Strait. Uniporal oscules are on the top surface. (b): Cross-section of a Stelletta raphidiophora (Ancorinidae) collected on the ‘Schultz Massive’ seamount (Greenland Sea) (ZMBN 85223). The grayish thick cortex is clearly visible. Specimen is 13 cm in diameter. (c): Calthropella geodioides (Calthropellidae) collected South of the Azores (ZMAPOR 21659). (d): Thenea valdiviae (Pachastrellidae) collected on the Norwegian coast. (e): Characteristic Astrophorida microscleres. ox – oxyaster of Geodia papyracea (diameter: 23 µm); st – sterraster of Geodia barretti (diameter: 80 µm); as – aspidaster of Erylus expletus (length: 330 µm); mi – microrhabd of Pachymatisma normani (length: 20 µm); pl – plesiaster of Poecillastra compressa (diameter: 37 µm); sa – sanidaster of Stryphnus raratriaenus; am – amphiaster of Characella pachastrelloides (length: 18 µm); sp – spiraster of Thenea levis (length: 23 µm). (f): cross-section of the cortex of Geodia barretti showing the skeleton organization. ec – ectocortex made of a thin layer of strongylaster and microxeas. en – endocortex made of a thick layer of sterrasters. ch – choanosome. tr – triaene supporting the cortex. Scale: 1 mm. (g): Characteristic Astrophorida megascleres. cal – calthrop of Pachastrella sp. from Norway (actine length: 100 µm); tr – long-shafted triaene of Stelletta sp. from Panama (rhabdome length: 850 µm); dicho – dichotriaene of Characella pachastrelloides (rhabdome length: 500 µm); ana – cladome of anatriaene of Geodia tumulosa from Panama (clad length: 24 µm); disco – discotriaene of Discodermia polymorpha (disc diameter: 180 µm) (photo: A. Pisera); phyllo – phyllotriaene of Theonella sp. (cladome: 730 µm) (photo: A. Pisera).