Calthropella Calthropella geodioides (Carter, 1876)

Van Soest, Rob W. M., Beglinger, Elly J. & De Voogd, Nicole J., 2010, Skeletons in confusion: a review of astrophorid sponges with (dicho-) calthrops as structural megascleres (Porifera, Demospongiae, Astrophorida), ZooKeys 68, pp. 1-88 : 48-50

Calthropella Calthropella geodioides (Carter, 1876) Figs 24 A–G

Pachastrella geodioides Carter 1876: 407, pl. XIV fig. 23.

Calthropella geodiides (sic); Sollas 1888: 111.

Corticella geodioides ; Topsent 1904: 77, pl. IV fig. 14, pl. X fig. 12.

Calthropella geodioides ; Burton 1956: 142.

Pachastrissa geodioides ; Lendenfeld 1903: 80; Van Soest and Hooper 2002: 132, fig. 2D.

Material examined.

ZMA Por. 21666, EMEPC/G3 –D03A–Ma 012, Azores, Terceira Island, 38.4265°N; 26.8206°W, 1201 m, coll. J. Xavier, 18 May 2007.

Specimens provided by Dr Joana Xavier, as yet unregistered: EMEPC/G3 –D01– Ma005, Azores, São Jorge Island, 38.48°N; 27.798°W, 1222 m, 17 May 2007; EMEPC/G3 –D02– Ma006, Azores, Terceira Island, 38.5530°N; 26.7083°W, 744 m, 18 May 2007; EMEPC/G3 –D33A–Ma 011a, S of Azores, Cruiser Seamount, 32.2570°N; 27.553°W, 643 m, 4 June 2007; EMEPC/G3/08.30, S of Azores, Atlantis Seamount, 33.916°N; 30.171°W, 1132 m, 30 October 2008.

Description.

Flat mounds (Fig. 24A) and thick crusts, rounded off at the edges. Size up to 5 ×3.5× 1 cm. Surface generally smooth-looking and lacking obvious apertures. Rough to the touch, hard but crumbly. Colour white or cream (alcohol).

Skeleton: with a dense crust of microscleres carried by triaene megascleres, with scattered bundles of oxeas, which appear mostly broken and are sometimes entirely absent.

Spicules: calthrops, dichocalthrops, (broken) oxeas, tuberculated spherasters, oxyasters.

Calthrops (Fig. 24 B–C), with common triactine forms, in a wide size range, cladi 102 –350.9– 705 × 11 –51.5– 128 µm, cladomes 150 –471.4– 1050 µm, possibly divisible in two categories (cladi lengths 102-180 and 434-705 µm).

Dichocalthrops (Fig. 24D), few (absent in some specimens) and fairly small: protocladi 75-92 × 12 µm, deuterocladi 28-31 µm, rhabdome 92-120 µm, cladome 128-183 µm.

Oxeas (visible in Fig. 24B) invariably broken, at least 500 µm in length and 5 µm diameter. Absent in some specimens (Sollas gives oxea size 736 × 9.3 µm).

Oxyasters (Fig. 24E) with conical rays, perhaps to be considered oxyspherasters, not common, 13-18 µm.

Tuberculated spherasters (Fig. 24 F–G), quite variable, in some specimens entirely smooth and of irregular oval shape, usually in a large size range 7-28 µm, possibly divisible in two overlapping size classes (7-12 and 23-28 µm).

Habitat.

On rocks in deep water, 599-1222 m.

Distribution.

Off Cabo São Vicente, Portugal; Azores. Burton (1956) lists the species for Madeira, but the basis for that is not clear.

Remarks.

Topsent (1904) and Pulitzer-Finali (1983) both point out the great similarity of Calthropella simplex and Calthropella geodioides . Points of difference apparently are the absence of dichocalthrops and oxeas in Calthropella simplex . In our present series of samples we could not find any oxeas in samples Ma012 and Ma005 (see above) and in the other samples they were invariably single, not forming bundles or radiating towards the surface and appeared to be broken generally in all sections and spicule mounts. Possibly this was artefactual. Dichocalthrops were rare to extremely rare in all studied samples. Dichocalthrops that were encountered were all in the small size class of triaene megascleres (less than 200 µm cladome size) and often were not ‘complete’, i.e. only one or two of the cladi were forked.

We believe that the two species simplex and geodioides could very well be the same species and could eventually be merged, but we will await further studies including molecular sequencing.

Topsent’s (1897) variety of Calthropella geodioides from Ambon (Indonesia) is not close to the present species. It shares the presence of oxeas and dichocalthrops with Calthropella geodioides but calthrops are much smaller (200 µm) and thick–centred euasters are only 10-12 µm. It is redescribed in Desqueyroux-Faúndez (1981) but remains ill-known (see below).