Cyamon hamatum, Soest, Rob van, Carballo, Jose Luis & Hooper, John, 2012

Soest, Rob van, Carballo, Jose Luis & Hooper, John, 2012, Polyaxone monaxonids: revision of raspailiid sponges with polyactine megascleres (Cyamon and Trikentrion), ZooKeys 239, pp. 1-70 : 28-29

Cyamon hamatum sp. n. Figs 15 A–C

Cyamon vickersii ; Burton and Rao 1932: 355 (S India).

Not: Cyamon vickersii (Bowerbank, 1864)

Material examined.

Type specimen: Holotype (schizotype), 1 slide BMNH 1931.1.1.19a, labeled Cyamon vickersii (Bow.) Ind. Mus. Coll. in Burton’s handwriting. Presumably the type specimen was at one time lodged in the collections of the Indian Museum, Kolkata, India, but present whereabouts are unknown. It is likely housed in the Zoological Survey of India, Kolkata.

Type locality: India, 21 miles S.W.W. of Mangalore, 4 May 1888.

Description.

partly from Burton and Rao 1931:

The single representative is a portion of a dull brown spherical mass. It agrees with the specimen described by Dendy (l.c.) except that the longest ray of the pseudactines bears a few recurved rays on the shaft and a crown of spines at the apex; the basal rays of these spicules have spines at the apex only; and the styli are very scarce. Locality. - 21 miles S.W.W. of Mangalore, S India (4th May 1888).

The slide (Fig. 15A) contains thick sections of the skeleton, showing the usual columnar structure of thick styles and polyactines (Fig. 15B). The slide allows the recognition and measurement of the spicule complement.

Spicules: long thin styles, short thin centrotylote styles, short thick styles, polyactines.

Long thin styles, not frequent, invariably broken, longest fragment measured 1300 × 30 µm.

Short thin styles, wavy outline, faintly centrotylote, under light microscopy mostly looking smooth but occasionally some spines are visible on the pointed end and also in at least one spicule two spines on the rounded end, 272 –313.2– 355 × 2.5 –3.4– 5 µm

Short thick styles, smooth, curved rather strongly near the rounded end: 421 –495.6– 604 × 16 –19.9– 31 µm.

Polyactines (Fig. 15C), predominantly three-claded, but occasionally four-claded, with long basal clades with prominent recurved hook-like spines and with short, stub by lateral cladi spined only at the bluntly rounded apices, basal cladi 104 –114.2– 126 × 11 –14.8– 21 µm, lateral cladi 42 –47.8– 65 × 10 –11.7– 20 µm.

Etymology.

The adjective hamatus (L.), means provided with hooks.

Distribution.

South India.

Ecology.

No data.

Discussion.

It is with some hesitation that we decided to name this scanty material as a valid new species. Although measurements of the megascleres conform to or are close to those of Cyamon vickersii , the shape and spination of the polyactines is distinctly different, as Burton & Rao already observed. With their strong hooks on the basal cladi and the peculiar short crowned lateral cladi the polyactines are different from any other known Cyamon .