Kingdom Animalia Order Clathrinida Genus Arthuria Higher classification Arthuria | Phylum Porifera Family Clathrinidae Scientific name Clathrina alcatraziensis Rank Species | |
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Arthuria alcatraziensis is a species of calcareous sponge in the genus Arthuria from Brazil. It is named after the Alcatrazes Islands where it was discovered.
Description
The cormus is spherical, composed of thin, regular and tightly anastomosed tubes. The anastomosis of the external tubes is tighter than that of the internal ones. Surface is hispid because of the large amount of diactines. Water-collecting tubes are present. Colour is white when alive and beige when preserved.
The skeleton is composed of triactines, diactines and rare tetractines. The triactines and tetractines have no special organisation. They are equiangular and equiradiate. Actines are straight, conical and sharp. The apical actine of the tetractines is projected inside the tubes. It is straight or undulated, sometimes slightly curved near the tip, smooth, slightly conical to cylindrical and sharp. Diactines are perpendicular to the surface. They are slightly arrow-shaped, almost fusiform. The tip that penetrates the cormus is larger than the distal one. Both tips are sharp. The size of the diactines is very variable. On the surface, several trichoxeas are also present.