Calthropella Corticellopsis stelligera (Schmidt, 1868)

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 : 63

Calthropella Corticellopsis stelligera (Schmidt, 1868) Figs 32 A–C

Corticium stelligerum Schmidt 1868: 25, pl. III fig. 6; Desqueyroux-Faúndez and Stone 1992: 10, pl. I figs 4-6.

Corticella stelligera ; Sollas 1888: 281; Lendenfeld 1894: 18, pl. II fig. 11, pl. III fig. 49; Topsent 1895: 339, pl. XXII fig. 1.

Corticellopsis stelligera ; Bergquist 1968: 62.

Calthropella stelligera ; Cruz and Bacallado 1982: 81; Cruz 2002: 89; Voultsiadou and Vafidis 2004: 593.

Material examined.

Type fragment of LMJG 15352 from Sebenico, Northern Adriatic (slide in ZMA). There are further fragments, not examined, BMNH 1867.7.26.14, 45, 104, BMNH 1910.1.1.863, MZUS P0005, and slides BMNH 1868.3.2.5 and ZMB 6563).

Description.

From Schmidt (1868) and Topsent (1895), based on a fragment presented to the British Museum (Natural History), BMNH 1910.1.1.863. Encrusting on corals and bridging crevices between coral branches, thickness about 5 mm. Colour white (in dry condition), yellowish inside. Desqueyroux-Faúndez and Stone (1992) picture the Schmidt specimen of which a fragment was studied from Sebenico as a massively encrusting sponge of 4 × 4 cm, encrusted and riddled with shells. According to Sollas (1888) it has a thickness of 5 mm. Cruz (2002) reports pale yellow or greyish live colour. The World Porifera Database ( van Soest et al. 2008) has an in situ picture made by Dr B. Picton from a locality just off the coast of Marseille showing a pale yellow colour. No apparent oscules.

Skeleton: densely spiculous at the surface, organic with few spicules in the interior. No definite skeletal structure.

Spicules: calthrops, euasters.

Calthrops (Fig. 32B) or short-shafted triaenes (Fig. 32A), variable in size, cladi 142 –288.2– 356 × 16 –25.6– 33 µm (cladomes 212 –436.0– 570 µm), Topsent gives cladus lengths 130-400 × 12-30 µm.

Microscleres euasters in two categories (although the LMJG fragment available to us only contained a single one: strongylasters 16 –20.2– 22 µm in diameter (Fig. 32C) with microspined rays in the studied fragment). Schmidt (1868) gives 20 µm as size of the strongylasters, whereas the oxyasters were measured by him as 50 µm. Topsent gives only ray lengths, 30 µm for the oxyasters (which could conform to 50 µm in overall diameter), and 4-7 µm for the ‘chiasters’ (which seems a bit too short for an overall 20 µm diameter mentioned by Schmidt). Presumably the various type specimens have considerable size variation in the asters.

Habitat.

Fairly shallow water, from intertidal caves to 20 m.

Distribution.

Adriatic; Marseille; Canary Islands; NW Aegean Sea, 39°N; 25°E (Algeria is given by previous authors, but this is probably based on a misunderstanding of Schmidt’s text).

Remarks.

The species is the type of the preoccupied genus Corticella Sollas (1888) replaced by Corticellopsis Bergquist, 1968 (see Van Soest and Hooper 2002 for details). It is apparently quite rare as there are only a few records from the Mediterranean (Northern Adriatic, Greece, and unconfirmed from Marseille). Schmidt (l.c.) mentions Algeria in his text, but very probably refers to another Corticium species (either Calthropella candelabrum or Calthropella plicatum = Dercitus plicatus ). The species has been reported recently from the Canary Islands ( Cruz and Bacallado 1982 and Cruz 2002) as pale yellow or grey masses with a skeleton of calthrops with cladi of 60-320 µm, irregular chiasters (strongylasters) of 8-23 µm diameter, drawn with smooth rays, five–rayed oxyasters also drawn with smooth rays of 16-40 µm. Voultsiadou and Vafidis (2004) give calthrops cladi of 120-240 × 20 µm, ‘chiasters’ with 5-8 µm ray lengths, and six–rayed oxyasters of 20-28 µm ray length. They also mention the presence of considerable amounts of oxeas, but these were assumed to be foreign. The various measurements of either ray length or overall diameter make it difficult to monitor the size variation of the asters. This species needs to be revised further, based on examination of all extant specimens.