Polymastia zitteli A. QM G
Creators: name: Ekins, Merrick
name: Erpenbeck, Dirk
name: Wörheide, Gert
name: Hooper, John N. A.
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Porifera
Demospongiae
Polymastiida
Polymastiidae
Polymastia
Polymastia zitteli

description: Polymastia zitteli (Lendenfeld, 1888)
Figures 1, 2 & 11.
Sideroderma zitteli Lendenfeld, 1888: 211.
Polymastia zitteli: Hallmann 1914: 400–402, pl. XV (Fig. 6); Plotkin & Janussen 2008: 109–110, Fig 6.
Material examined: QM G337502, Central Eastern Commonwealth Marine Reserve, New South Wales, Australia, -30.0977, 153.8987 to -30.1193, 153.8745, 2429–2518 m, Beam Trawl, Coll. Merrick Ekins on RV Investigator, Cruise IN2017_ V03, 1 specimen, sample 86-150, 5/ VI /2017; QM G339438 same collection details as QM G337502, sample 86-150.1.
Morphology: The first specimen QM G337502 is a grey-coloured anemone shaped cylindrical vase with medusoid papillae on the upper surface. There are about 22 papillae of tubular to tapering shape of up to 10 mm in length and 1–4 mm in width. There are terminal oscular apertures of less than 0.5 mm, diameter on the papillae. The sponge was attached to the substrate by a pedestal measuring 43 mm in height, 36 mm in width at the broadest part and only 25 mm wide at the base. The specimen has clearly flattened upon collection and preservation, and is now only 8mm thick. The surface is macroscopically smooth, and velvety. The cortex is firm, detachable and cream in colour, the same colour as the papillae and the choanosome. On one side of the body there is a flattened depression, either from a previous injury or where the sponge has been overgrowing some structure.
The second specimen QM G339438 is a lighter cream in colour than specimen QM G337502, but it has a similar morphology. It is 27 mm in height, 18 × 7 mm in width, and 17 papillae on the upper surface ranging from 2–4 mm in height and 1–2 mm in width. It also has a depression/injury on one side where part of the cortex has been removed.
Skeleton:The cortical skeleton is composed of bouquets of the small subtylostyles, forming a palisade, producing a hispid surface 200–400 μm thick. The inner layer of the cortex is composed of a thin layer of tangential styles less than 100 μm thick. The choanosomal skeleton has a very cavernous open architecture with a loose reticulation formed by the tracts of principal styles, which lie against and are attached to the lower cortex layer, forming a porous wall on the outer layer of the choanosome. The majority of space within the choanosome is aquiferous canals, with occasional principal styles in a disorganised array.
The papillae also have a very hispid palisade of small subtylostyles projecting directly outwards from the surface, with the large oxeote styles forming the skeleton paratangentially somewhat disorganised but mainly in columns, in a similar fashion to the rest of the sponge body. The choanosomal skeleton of the papillae is also very open and cavernous with aquiferous canals.
Spicules: The oxeote fusiform styles provide the support of the skeleton, they are 613-(964)-1450 × 11.6-(20.2)- 31.1 μm (n=59). There was a continuous range in sizes of styles that could not be differentiated into principal and intermediate sizes. The thin slightly curved subtylostyles forming the hispid surface are 201-(260)-412 × 2.2-(4.4)- 6.7 μm (n=29). In the second specimen the spicules are of similar dimensions i.e. 613-(1132)-1830 × 10.6-(18.3)- 29.3 μm (n=57). The thin slightly curved subtylostyles forming the hispid surface are 173-(231)-329 × 2.3-(4.2)-6.0 μm (n=27).
Distribution: New South Wales, Australia and Antarctica, abyssal depths.
Ecology: Mud substrate.
Molecular Data: 28S-C region barcode of G337502 (ENA Accession number OY741342). Recent sequencing of many Artic species (Plotkin et al. 2018) has allowed comparison with many species, although P. zitteli was not included in their data set. This sample is genetically different from all other samples analysed in this study.
Remarks: This is the third record of P. zitteli after its first description from Port Jackson in Australia (Lendenfeld 1888; Hallmann 1914) and the later record from the Antarctic (Plotkin & Janussen 2008). Our specimens differ from the previously described sponges in lacking the extra small tylostyles mentioned by Hallmann (1914) and intermediately sized styles noted by Plotkin & Janussen (2008). Furthermore, our specimens are distinguished by a massive upright body resembling a sea anemone, while the previously described individuals are all thinly encrusting.
In his original description Lendenfeld (1888) mentions 150–200 μm long tylostyles and 1 mm long styles. In his redescription of Lendefeld’s type specimen Hallmann (1914) lists 500–1200 μm long styles, choanosomal tylostyles, 145–210 μm long, and cortical tylostyles, 85–135 μm long. Additionally, he indicates that P. zitteli shares similar polytylote characteristics of the large styles with those of P. isidis Thiele, 1905, and P. affinis Thiele, 1898; none of which bear resemblance to our specimens.
Plotkin & Janussen (2008) described large styles, 812–1315 μm long, intermediate styles, 340–598 μm long, and subtylostyles, 247–333 μm long, for their specimen. Furthermore, they also describe the choanosomal skeleton of P. zitteli as reticulated, also found in the two specimens described above. This feature is also found in P. crocea Kelly-Borges & Bergquist, 1997, from New Zealand, and P. boletiformis (Lamarck, 1815) from the North Atlantic. Polymastia boletiformis has been well redescribed by Plotkin et al. (2018), having only small and intermediate size categories of subtylostyles, and is a large yellow sponge with larger papillae. Polymastia crocea is another yellow shallow water species, with an unusual three layered cortex.
description: Published as part of Ekins, Merrick, Erpenbeck, Dirk, Wörheide, Gert & Hooper, John N. A., 2023, Deep Water Polymastiidae (Porifera, Polymastiida) from the South West Pacific, pp. 57-88 in Zootaxa 5369 (1) on pages 82-84, DOI: 10.11646/zootaxa.5369.1.3, http://zenodo.org/record/10146837