Nubes tubulata Reiswig, Dohrmann & Kelly, 2021

Reiswig, Henry M., Dohrmann, Martin, Kelly, Michelle, Mills, Sadie, Schupp, Peter J. & Woerheide, Gert, 2021, Rossellid glass sponges (Porifera, Hexactinellida) from New Zealand waters, with description of one new genus and six new species, ZooKeys 1060, pp. 33-84 : 33

Nubes tubulata Reiswig, Dohrmann & Kelly sp. nov.

Figs 4 , 5

Material examined.

Holotype NIWA 126159, RV Sonne Stn SO 254/36ROV10_BIOBOX7, Seamount No. 986, off Hawkes Bay shelf, 39.990°S, 178.214°E, 782.8 m, 09 Feb 2017 . Paratype NIWA 126160, RV Sonne Stn SO 254/36ROV10_BIOBOX10, Seamount No. 986, off Hawkes Bay shelf, 39.989°S, 178.214°E, 767 m, 09 Feb 2017 .

Distribution.

Known only from the type locality, Seamount 986 off Hawkes Bay shelf, east of North Island, New Zealand (Fig. 4A ).

Habitat.

Attached to hard substratum; depth 767-783 m (Fig. 4B ).

Description.

Morphology of the holotype and paratype a thick-walled, tubular sponge, attached to hard substratum by a narrow base (Fig. 4B ). A round osculum of moderate size is terminal and opens into a deep atrial cavity. The margin is sharp and there are indications of sparse diactin marginalia in deck images, but we have been unable to verify them in the material at hand. The dermal surface has a dense covering of raised, prostal, hypodermal pentactins (Fig. 4C, D, I ) projecting up to 1 cm from the surface proper. There is indication in some of the deck images of long diactins projecting sparsely up to 6 cm from the dermal surface, especially basally, but these may be choanosomal diactins pulled out during collection; we have not found such large diactins in the material we had for examination. Dimensions of the holotype are ~ 13.3 cm high, 7.0 cm wide, and 10.8 (9.2-13.3) (n = 9) mm in body wall thickness; the osculum is 2.2 cm in diameter in situ. The paratype is 19.5 cm high, 13.4 cm wide, and body wall is 7.4 (5.5-9.3) (n = 11) mm in thickness. The osculum is 4.2 cm in diameter in situ. Texture is soft, compressible, and resilient, neither hard nor fragile. Surface of the dermal side is covered by a thick layer of projecting hypodermal pentactins (Fig. 4E ). The dermal lattice is torn apart, and dermalia reside in preserved specimens as attached flakes on the hypodermalia (Fig. 4G ). The atrial layer retains the atrial lattice covering smaller apertures (Fig. 4F, H ); no large megascleres project into the atrium. Colour in life is transparent white, preserved in ethanol is medium brown (Fig. 4C ).

Skeleton. Choanosomal skeleton consists of a loose, vacuolar network of thin choanosomal diactins, large choanosomal hexactins, and the thicker proximal rays of the hypodermal pentactins. There is no evidence of fusion between any spicules. Microscleres are scattered evenly throughout the choanosome. Ectosomal skeleton of the dermal side consists of abundant prostal pentactins supporting a delicate lattice of hexactine, pentactine, and stauractine dermalia. The atrial ectosome lacks hypoatrial pentactins but has bands of diactins that support the atrial lattice of hexactins, providing greater support than available to the dermal lattice. Microscleres are present as in the choanosome.

Spicules. Megascleres (Fig. 5 ; Table 2 ) are prostal hypodermal pentactins, choanosomal diactins, choanosomal hexactins, dermalia, and atrialia. Prostal hypodermal pentactins (Fig. 5A ) are mostly large, raised paratropal forms (90% of 68 scored) with long, very curved tangential rays, but some regular, crucial forms occur (10%) in smaller forms especially near the margin. Tangential rays are 1.7 × the shorter, straighter proximal rays. The spicules are smooth except for the rough sharp tips. Choanosomal diactins (Fig. 5B ) are straight or strongly curved, usually with undetectable central swellings; they are smooth except for the rough, slightly inflated tips. Choanosomal hexactins (Fig. 5C ) are large forms with strongly curved or nearly straight, nearly equal length rays, which are otherwise similar to those of the hypodermalia. Dermalia (Fig. 5D ) are entirely spined and consist of stauractins (31% of 387 scored) and similar forms with reduced fifth ray (subpentactins) or both fifth and sixth rays in one axis (subhexactins) (64%) with a few (1-2%) as tauactins, diactins and paratetractins. It was not possible to differentiate the subpentactins and subhexactins either wet in dishes or mounted spicule microscope slides. Tips are either rounded or more often sharp. Atrialia (Fig. 5E ) are entirely spined and mostly subhexactins (71% of 125 scored) with one ray reduced or hexactins (26%) with all rays of nearly equal length; a few (1-2%) are stauractins and tauactins. Ray tips are sharp-pointed.

Microscleres (Fig. 5 ; Table 2 ) are oxyhexasters and their variants, with hemioxyhexasters being the most common, and anisodiscohexasters. Oxyhexasters and hemioxyhexasters (Fig. 5F, G ) have very short smooth primary rays and long straight secondary rays entirely ornamented with small, reclined spines. Secondary rays on each primary ray vary from 1-4. Anisodiscohexasters (Fig. 5H ) are spherical with stellate discs with 4-6 marginal claws on the ends of terminal rays. Primary rays are smooth and end in strobiloid discs with a short central projecting knob. Each primary strobilum supports 30-40 terminal rays with undulating, probably helically coiled, finely rough shafts of unequal lengths. Terminal discs vary in diameter with shaft length, the longer shafts carrying the larger discs, e.g., a series 1.7, 2.5, 3.1, 3.4, 3.6, 5.4, 6.9 µm diameter for shafts 15.0, 20.5, 23.5, 27.3, 32.0. 33.4, 37.1 µm in length. These spicules look very different in LM (lower image) and SEM (upper image) due to collapse of the rays during drying for SEM and support of them by balsam in LM.

Etymology.

Named for the tubular morphology of the sponge ( Nubes tubulata , tubular; Latin).

Remarks.

The characters of these two New Zealand specimens are inconsistent with the present diagnoses of all Rossellinae genera except Vitrollula Ijima, 1898. They differ, however, from those of V. fertilis Ijima, 1898, the only species in the genus, in characters not used as diagnostic. These are that V. fertilis has a smooth surface without raised hypodermalia, but the two new specimens have a bristly surface with raised hypodermalia, and that the discohexasters of V. fertilis are isodiscohexasters while those of the new species are anisodiscohexasters. In view of these differences, we opt not to include the new species in Vitrollula nor to change the diagnosis of that genus at this time. We choose to erect a new genus in Rossellinae with characters of this and the following second species described below, and designate this species as Nubes tubulata gen. nov., sp. nov.

Figures

Figure 4. Nubes tubulata gen. nov., sp. nov., holotype NIWA 126159, distribution, skeleton and morphology A Distribution in New Zealand waters B holotype in situ C holotype, deck image D holotype, deck image showing moderate-sized osculum and veil of hypodermal pentactins (deck images by PJS) E dermal surface with dense veil of prostal hypodermal pentactins F atrial surface without a hypodermal veil G closer view of dermal surface with disrupted lattice H closer view of atrial surface with intact lattice over exhalant apertures I section of body wall, dermal surface on left side. Image B captured by ROV Team GEOMAR, ROV Kiel 6000 onboard RV Sonne (voyage SO 254), courtesy of Project PoribacNewZ, GEOMAR, and ICBM.

Figure 5. Nubes tubulata gen. nov., sp. nov., holotype NIWA 126159, spicules A whole prostal hypodermal pentactin and enlarged ray ends B whole curved and straight choanosomal diactins with two enlarged ends; scales of whole spicules and parts in B and C as in A; C whole choanosomal hexactin with two enlarged ray ends D two dermalia, a subhexactin, and a stauractin, with enlarged ray ends and centres E two atrialia, a pinular subhexactin, and a regular hexactin with enlarged centrum of the pinular subhexactin and a ray end; scales of whole spicules and parts as in D; F two oxyhexasters G enlarged terminal ray of an oxyhexaster H anisodiscohexasters, from SEM preparation (above) and LM preparation (below).