Hymeniacidon globularis n. sp.

urn:lsid:zoobank.org:act: CCD8E346-515C-41C7-A8F5-A20EE67BE55A

Figure 12

Diagnosis. Light yellow, globular shape, highly compressible unlike most Hymeniacidon species which have chimneys or are encrusting.

Etymology The species name refers to the sponge habitus which is invariably globular in BC shallow waters.

Material Examined Holotype RBCM 023-00001 - 001, Stn NM 351, Sakinaw Rock, Sechelt Inlet, BC, 49° 33.988’ N / 123° 48.174’ W, coll. N. McDaniel, 28 Nov 2016, 20 m depth, 1 specimen . Paratypes RBCM 018- 00142 - 004, Stn NM 229, Piper Point, Sechelt Inlet, BC, 49° 32.755’ N / 123° 47.537’ W, coll. N. McDaniel, 11 May 2011, 24 m depth, 1 specimen; RBCM 018-00158 - 002, Stn NM 255, Christie Islet, Howe Sd, BC, 49° 29.919’ N / 123° 17.985’ W, coll. N. McDaniel, 19 May 2011, 17 m depth, 1 specimen; RBCM 024-00015 - 001, Stn NM 350, Miller Islet, Jervis Inlet, BC, 49° 47.249’ N / 123° 56.749’ W, coll. N. McDaniel, 27 Nov 2016, 20 m depth, 1 specimen .

Description

External (Figure 12A) Holotype RBCM 023-00001 - 001. The holotype is an oblong puffball 10 cm longest diameter by 5 cm high in life; flattens and compresses on preservation . Other specimens examined averaged 3 cm diameter alive. All specimens form highly compressible puffballs. All specimens examined have one approximately centrally located osculum surrounded by a slightly raised rim, 5 mm diameter in the holotype and 2–3 mm diameter in other specimens examined. Ostia numerous over the entire surface, 0.5–1 mm diameter. Colour is cream yellow in life; beige in alcohol; consistency is soft but not easily torn.

Skeleton (Figure 12B, C –measurements from the holotype) The sponge skeleton is 1 to 2 mm thick and forms the skin of a hollow subspherical body (Figure 12B). Loose bundles of spicules arise from the inside surface and run vertically to the surface in discontinuous tracts (Figure 12C). Many loose spicules and unoriented bundles fill spaces between vertical bundles (Figure 12C). Tracts are 30 to 50 µm thick and from 3 to 20 spicules across. Tracts are not systematically cross connected (no reticulation is formed) but are randomly cross connected by unoriented loose spicules or bispicular tracts. Choanosome tracts widen into brushes 200 to 300 µm from the surface and may penetrate the surface up to 100 µm. There is no specialized ectosome separable from the general skeletal structure.

Given the highly compressible habitus, a live sponge will have large choanosomal aquiferous lacunae which are compressed immediately upon removal from water. Some relatively large lacunae (up to 300 µm across) are still present in flattened preserved specimens.

Spicules (Figure 12 D). Spicules are exclusively straight subtylostyles with elliptical heads, cylindrical shafts and moderately short apices with slightly rounded tips (hastate). Many are polytylote, a frequent characteristic of the genus. Table 12 lists spicule dimensions of specimens examined.

There is only one other described Hymeniacidon that forms a largely hollow sac: H. calva (Ridley, 1881) from Magellan Straits; no depth information was provided by Ridley. Ridley (1881, p. 115) describes the sponge as having a dermal membrane. Ridley’s sponge has shorter styles (based on Ridley’s figure) 77 x 13 µm and choanosome tracts penetrate the surface in tufts. The geographical separation makes conspecificity unlikely.