Description

Description: The holotype is a round, thin specimen 12 mm in diameter at its widest (Fig. 6 A, B). It is only 1 mm in height and encrusting on the base of the stem of a dead Keratoisis sp. It has a rough surface due to the protruding tangential styles. The preserved sponge has folds on the upper surface (Fig. 6 B), most likely as the sponge was of a greater height underwater (possibly 2 – 4 mm in height) that collapsed once out of the water. The sponge has no apparent oscula, although it is possible there were oscules terminal in what could be conules of several millimetres in height, but these may have been destroyed in collection by the rock dredge. As is usual with this genus there are numerous scattered ostia 0.5 mm in diameter, that are obvious on the surface (Fig. 6 C). The sponge is white on deck and in preservative, although highly translucent when preserved in ethanol. Skeleton: The ectosomal skeleton consists of a tangential layer of styles, often surrounding the apparently randomly scattered ostia of 0.3 – 0.5 mm in diameter (Fig. 6 D). The choanosomal skeleton was not obvious but consisted of the usual supporting bundles of styles typical for this genus Spicules: The megascleres are styles, which are abundant, fusiform, straight, sharply pointed and thickest in the centre (Fig. 6 H, I). The blunt end is much narrower than the middle and has a rounded style end. They measure 337 – (410) – 574 x 6.7 – (10.4) – 14.7 μm, n = 29. The large diancistras (I) are not common, with the shaft twisted less than 45 o, the thin sharp fimbriae run the entire length of the inner surface except around the notch (Fig. 6 E). These measure 102 – (108) – 119 x 5.9 – (8.3) – 10.5 μm, n = 12. The medium sized elongated diancistras (II) are common, with the shaft twisted greater than 90 o, and have large equal, almost touching elongated fimbriae (Fig. 6 F). These are less than half the size of the diancistras (I), and measure 28.8 – (46.6) – 66.1 x 1.2 – (2.1) – 3.1 μm, n = 42. The small diancistras (III) are not common, with the shaft twisted greater than 90 o (Fig. 6 G). These have large equal alae with almost touching curvaceous fimbriae. These small diancistras are approximately half as smaller than the intermediate-sized diancistras (II) again, measuring 21.4 – (23.6) – 26.3 x 1.0 – (1.3) – 1.5 μm, n = 10.

Common Names

Taxonomic Hierarchy

Kingdom: Animalia

Phylum: Porifera

Class: Demospongiae

Order: Merliida

Family: Hamacanthidae

Genus: Hamacantha

Species: Hamacantha levii Ekins & Hooper, 2023