Cyamon amphipolyactinum van Soest, Carballo & Hooper 2012

Cyamon amphipolyactinum is 'n gewone sponsspesie uit die familie van die Raspailiidae. Die wetenskaplike naam van die spesie is die eerste keer geldig gepubliseer in 2012 deur Van Soest, Carballo & Hooper.

Cyamon amphipolyactinum adalah spesies spons yang tergolong dalam kelas Demospongiae. Spesies ini juga merupakan bagian dari genus Cyamon dan famili Raspailiidae. Nama ilmiah spesies ini pertama kali diterbitkan pada tahun 2012 oleh Van Soest, Carballo & Hooper.

Seperti spons pada umumnya, spesies ini memiliki tubuh yang berpori dan permukaan yang keras seperti batu. Selain itu, Cyamon amphipolyactinum juga dapat menyerap oksigen dari air melalui proses difusi.

Encrusting a sandstone flake accompanied by several other encrustations (position of holotype indicated by arrow in Fig. 4A). Lateral size of holotype approximately 4x3 cm, thickness up to 3 mm. Color red in life, light orange brown in alcohol. Surface irregularly grooved and venous. Consistency soft, easily damaged. Skeletal structure: A basal mass of polyactine spicules pierced by erect single or bundled thick styles, alternated by long thin styles protruding beyond the surface. At the periphery, the long styles are surrounded by bouquets of thin (tylo-)styles. Spicules: of five types, long thin styles, short thin styles, short thick styles, large polyactines and small double polyactines. Long thin styles (Figs 4B, B1), flexuous or curved snake-like, most were broken in the slides, size (based on 7 complete spicules): 1058–1294.0–1643 × 6–9.3–12 µm. Short thin styles (Figs 4C, C1), curved, faintly tylote at the base, 288–374.9–456 × 2–3.2–4 µm. Short thick styles (Figs 4D, D1), characteristically curved in the upper half, heads relatively thick with lower half narrowing strongly towards a sharp point, size varying strongly, 204–352.1–558 × 9–17.4–33 µm. Large polyactines (Figs 4E, E1), in full-grown condition with all cladi ending in prominent, heavily spined knobs (Fig. 4E1) except one, the basal cladus, which is bluntly pointed. Cladi are less heavily spined towards the centre and at low magnification appear smooth. Growth stages may be partly or entirely without spines, but they are recognizable as unfinished by their irregularly undulating surface. The number of cladi varies between three and seven. In the largest spicules the cladi may be occasionally bifid. Basal cladi usually slightly shorter than the remaining cladi. Overall length of cladi regardless of condition is 18–51 × 3–10 µm. Three-claded forms (rare), basal cladus 36–39 × 8–9 µm, lateral cladi 39–51 × 7–10 µm. Four-claded forms (most common), basal cladus 18–51 × 3–9 µm, lateral cladi 22–51 × 3–9 µm. Five-claded forms (also common), basal cladus 21–36 × 6–10 µm, lateral cladi 30–48 × 7–10 µm. Six-claded forms (rare), basal cladus 21–36 × 4–5 µm, lateral cladi 24–38 × 4–6 µm. Small double polyactines (Figs 4E and F), here termed amphipolyactines as they are obviously proliferated at both ends of the basal cladus. At first glance they resemble amphiasters or metasters (family Pachastrellidae Carter, 1875), but when studied with SEM they are similar in structure and ornamentation to the larger polyactines, but lack the swollen apices of the cladi of the larger ones. Cladi number from 5 to 10 (average 6.4) and they are spined in full-grown condition, smooth when still unfinished. Longest axis, presumably homologous to the basal cladus, is 18–30 × 1–4 µm, cladi 9–24 × 1–3 µm.

(Fig. 5). So far known only from the sandstone ridges of coastal flats of the Banc d’Arguin, Mauritania, West Africa.