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Sollas, 1888

Species Overview

Pachymatisma normani Sollas (1888) is recently rediscovered in Norwegian waters after being considered a junior synonym of P. johnstonia for more than a century. Differences are in the arragement of the oscules (not in rows as in P. johnstonia) and in the spicules sizes and categories.


Taxonomic Description

Colour: White to light brown.
Shape, size, surface and consistency: Most of the specimens have a massive irregularly bumpy flattened shape. The biggest specimen found had a diameter of 10 cm and a height of 4 cm. Like P. johnstonia, most specimens appear to be attached through a large basal area, occasionally a specimen is stalked. Choanosome brownish to whitish. Uniporal oscules (2-3.5 mm) are white-rimmed, slightly raised or flushed with surface. They are gathered in small groups in any area of the sponge or restricted to a flat top. 'Fusion' of two oscules was seldom observed, these could also be interpreted as very simple cribriporal oscules. Pores 0.1-0.01 mm in diameter, cribriporal, similar to those in P. johnstonia. The cortex is on average 1 mm thick but can reach 2 mm. Surface is rather smooth except in some sheltered hispid areas.
Spicules: Megascleres. All intermediates between strongyles and oxeas exist but the latter are far more abundant. Strongyles and oxeas are straight or bent, 400-2000 µm. Numerous fused oxeas forming 'X' or 'Y' shapes or even more complicated assemblies, were observed. Large plagiotriaenes are present, with rare dichotriaenes (found only in one specimen), 220-1130 µm. Microscleres. Large spiny regular oxyasters with 4-7 slender actines are fairly abundant, 36-122 µm. Spiny microrhabds, sometimes centrotylote, 10-34 µm. Large, slightly flattened sterrasters are present, 80-228 µm with all intermediate forms between globular and ellipsoid.
Skeleton: The ectocortex of microrhabds is usually poorly developed, except in pore areas. The endocortex of sterrasters is quite developed. Microrhabds and the flattened sterrasters are tangentially disposed with respect to the surface. Microrhabds can also be found in the wall of large canals. Plagiotriaenes and oxeas are more or less radially disposed near the surface; this arrangement is less obvious in the interior of the sponge. Oxyasters can be found throughout the choanosome. The skeleton is similar to that of P. johnstonia, except for the presence of hispid areas in sheltered convolutions where oxeas cross the cortex.
Distribution: To date, P. normani has been unambiguously identified only in Norway. According to Koltun (1966), it can be found in the south-west of the Barents Sea.
Ecology: Pachymatisma normani lives attached to the steep cliff walls of the fjords (200-400 m) and in Norwegian Lophelia pertusa (L., 1758) reefs. In the latter case, it was found living on coral rubble. In the Skagerrak, P. normani was found living on a rock and mud bottom (149-137 m). Burton (1931) found two specimens in the Foldafjord at two different stations: 50-100 m and 10-75 m.
Etymology: named after the reverend A.M. Norman.
Type material: Holotype: presumably lost (Clare Valentine, personal communication). Neotype: adult specimen broken in two pieces (9 cm and 7 cm) collected at the type locality: Skorpeodden in the Korsfjord (60°10'N 05°10'E), Norway; water depth: 200- 400 m. Bergen Museum collection number: ZMBN 77858. Collected by H.T. Rapp, 21 March 2007.

Remarks

Since the material was collected by dredging, much is fragmented and only three complete specimens are known. P. normani differs from P. johnstonia by (1) outermorphology, (2) larger upper size of the spicules, especially the sterrasters, (3) geographic distribution, and (4) there are samll genetic differences.
Source: Cardenas et al. 2007.

Pachymatisma normani