Isabella mirabilis, Schlacher-Hoenlinger & Pisera & Hooper, 2005

Schlacher-Hoenlinger, Monika A., Pisera, Andrzej & Hooper, John N. A., 2005, Deep-sea “ lithistid ” assemblages from the Norfolk Ridge (New Caledonia), with description of seven new species and a new genus (Porifera, Demospongiae), Zoosystema 27 (4), pp. 649-698 : 670-673

publication ID	https://doi.org/ 10.5281/zenodo.5393958
persistent identifier	https://treatment.plazi.org/id/03CE2F2C-7E1F-D942-3BE9-FAA2FDE8FDA1
treatment provided by	Marcus
scientific name	Isabella mirabilis
status	sp. nov.

Treatment

Isabella mirabilis View in CoL n. sp.

( Figs 3A View FIG ; 12 View FIG ; 26 View FIG )

HOLOTYPE. — Jumeau-West seamount, Norfolk Ridge, 23°40’33”S, 168°00’E, 237-250 m, RV Alis, 21.VI.2001, Warén dredge, coll. T. Schlacher ( MNHN DCL 3903 About MNHN , a fragment of the holotype in QM [G318560s). GoogleMaps

ETYMOLOGY. — Named for the intense, dark purple stain excreted by this species ( mirabilis, Latin for wonderful, strange, causing wonder).

OTHER MATERIAL EXAMINED (see Table 1). — Antigonia, 180-250 m (QM G318737). — Jumeau-

West, 237-250 m (QM G318751, QM G318765). — Banc 2, 185- 207 m (QM G318803).

DESCRIPTION

Growth form

Massive, shallow cup-shaped, artichoke-like sponge with broad base and an uneven margin, and outer surface bearing numerous, blind, very short, evenly distributed fistules. Dimensions are approximately 4 to 5 cm high and 5 to 7 cm wide with an approximately 3 to 5.5 cm broad base.

Colour

Dark brown in etoh, discolours alcohol deep purple-brown.

Oscules

Not visible.

Texture

Hard, but not stony, brittle, with some compressible parts.

New “lithistids” (Porifera, Demospongiae) from New Caledonia

Surface ornamentation

Uneven, fistulose.

Ectosomal skeleton

Contains a layer of very abundant smooth dichotriaenes perpendicular to the surface and abundant microscleres. Microscleres at the surface are numerous forming a crust and consist of microspinose, often centrotylote and curved, microxeas and asymmetrical euaster-like streptasters.

Choanosomal skeleton

Composed of regular and slightly curved dicranoclones. These desmas form an extremely distinct root/vine-like mesh. Choanosomal microscleres are typically microspinose spirasters with long, more or less pointed rays. There are also thick bundles of long oxeas.

Megascleres

Dicranoclone desmas are regular, slightly curved, tripodal slender dicranoclone desmas which are

Schlacher-Hoenlinger M. A. et al.

completely smooth or bear numerous low, indistinct, smooth tubercles. Often the centrally locat- ed tubercle is higher than the others. Adjacent desmas produce a complex skeletal network via entanglement of their extremities, which is aided by the root/vine-like lateral extension of the desmas: 520-610 µm/25-45µm.

Dichotriaenes smooth, often with tips of the cladome bent in an angle and lower third of the rhabdome with several grooves: 523-784 µm long × 297-479 µm diameter (cladome).

Oxeas very long, but all broken, some shorter unbroken ones measure 468 × 7-8 µm, but it is unsure if they are native or foreign.

Microscleres

Microacanthoxeas (centrotylote): 65.9-107 × 3.86-5.6 µm.

Streptaster (spiraster) very variable, with slender arms: 17.5-25.9 × 15-20.8 µm.

Streptaster (resembling euaster, but asymmetrical with long, thick rays), diameter: 8.2-15.0 µm.

REMARKS

This species has a very distinctive gross morphology, very characteristic dicranoclones and euaster-like streptaster microscleres. No similar combination of microscleres is known so far in any described lithistids. All these characteristics suggest that the new species belong to a new genus within the family Corallistidae .