Polymastia invaginata Kirkpatrick, 1907

Ekins, Merrick, Erpenbeck, Dirk, Wörheide, Gert & Hooper, John N. A., 2023, Deep Water Polymastiidae (Porifera, Polymastiida) from the South West Pacific, Zootaxa 5369 (1), pp. 57-88 : 76-78

Polymastia invaginata Kirkpatrick, 1907

Figure 9 , Table 5

Polymastia invaginata Kirkpatrick, 1907: 271 ; 1908: pp. 15–16, pl. XII(1b), pl. XIV (5–15a); Burton 1929: 446; Koltun 1964: 26, pl. IV (10–14); Boury-Esnault & van Beveren 1982: 36–37, pl. IV (13–14), Figs 9 D–F , Plotkin & Janussen 2008:102- 109, Figs 4–5 , Tables 2–3 .

Polymastia invaginata var. gaussi Hentschel 1914: 49 , Taf. V, Fig. 4 .

Material examined: QM G315026 , Casey Antarctic Research Base, Windmill Islands, Antarctica, -66.2822, 110.5266, 30 m, SCUBA, Coll. M. Riddle & P. Goldsworthy, 10/XI/1997 ; QM G335958 , same collection details as QM G315026 ; QM G311143 , Mc Murdo Base , Cape Armitage , Ross Island , Antarctica, -77.85, 166.67, 20 m, north Jetty, Judy’s 1 st dome site, NCIS Q66C3091 -Z, SCUBA, Coll. Australian Institute of Marine Sciences and National Cancer Institute, 18/X/1989 .

Morphology: Solitary circular sponge with a bulbous cushion base 52–83 mm wide and 25–40 mm in height ( Fig. 9 A–G ). Partially burrowing with a single large contractile and retractile central papilla, 13–19 mm wide, height 0–3 mm above the dermis in preservative, and judging by Fig. 9 A, B equal in height as width in vivo. There is a large single oscule at the top of the papillae (1–2 mm wide). The sponge is grey/brown in life and in ethanol, reflecting the colouration of the surrounding mud/silt. The papillae are ivory to cream in life and ethanol ( Fig. 9 A–G ). The sponge is firm but compressible, and is covered in a soft covering of fine hairs (except the papilla).

Skeleton: The ectosomal skeleton is composed of an erect palisade of smaller tylostyles on the base, absent from the papilla, with larger styles protruding out from the choanosomal tracts ( Fig. 9 H, I ). There is abundant sand/detritus on the surface providing grey colouration to the ectosome. The choanosomal skeleton consists of huge multispicular tracts diverging and providing support to the smaller ectosomal tylostyles ( Fig. 9 H, I ). Stellate formations of smaller tylostyles occur between the tracts ( Fig. 9 J ).

Spicules: Choanosomal principal styles tapering sight subtylostyle bases (hastate), tapering to sharp points ( Fig. 9 K ). Ectosomal tylostyles are straight to slightly curved and have a prominent tylote base ( Fig. 9 L ). Stellate tylostyles in the choanosome between the tracts, are indistinguishable from the tylostyles in the ectosome. Spicular measurements are given in Table 5 .

Distribution: Antarctic and Subantarctic waters

Ecology: Partially burrowing in soft mud

Molecular data: no unambiguous 28S-C region barcode could be generated from this species.

Remarks: These specimens match Kirkpatrick’s (1907) and subsequent authors’ descriptions of this species albeit with some variable spicule measurements between the publications. Plotkin & Janussen (2008) reviewed the various authors’ descriptions and measurements compared to their material, which is not repeated here. The location of this specimen from the Lord Howe Plateau is a range extension from the previous Antarctica and subantarctic records. In Plotkin & Janussen (2008), the P. invaginata samples from Antarctica deposited at the SMF, contain novel sceptre like spicules. Unfortunately, the P. invaginata specimens that were sequenced (Plotkin et al. 2017) were from a different cruise and are deposited at ZMBN. Plotkin et al. (2017) makes no mention of whether these samples have the sceptre like spicules. The morphology, skeleton and spicules match the original and more recent descriptions these new specimens also contain the stellate formations of tylostyles as reported by Kirkpatrick, (1907), Hentschel (1914), Koltun (1964), Boury-Esnault & van Beveren (1982), and Plotkin & Janussen (2008).

Figures

FIGURE 4. Radiella pumix sp. nov. A. The holotype QM G337516 attached to pumice. B. Paratypes QM G339364, still attached to the pumice. C. Upper surface of paratype QM G337616 showing the central papilla. D. Closeup of the fringe of the paratype QM G337616, showing the bouquets of tylostyles. E. Composite SEM image of a cross section through the holotype QM G337516 showing the central papilla and the radial tylostyle skeleton. F. Large tylostyles involved in the brush formation and the fringe. G. Intermediate tylostyles from the choanosome. H. Small tylostyles from the choanosome.

FIGURE 5. Radiella sclera sp. nov. Holotype QM G316333. A–B. Upper and lower surfaces of the preserved holotype. C–D. Light micrographs of sections through the radial thin ectosomal skeleton (C), and bouquets of tylostyles in the ectosome (D). E. Principal tylostyle. F. Enlarged view of principal tylostyle. G. Intermediate tylostyle. H. Enlarged view of intermediate tylostyle. I. Small tylostyle.

FIGURE 9. Polymastia invaginata Kirkpatrick, 1907. A. QM G315026 underwater. B. QM G311143 underwater. C. QM G315026 fixed. D. Cross section of QM G315026. E. QM G335958 fixed. F. QM G311143 fixed. G. Cross section of QM G311143. H. Composite section of QM G315026. I. section of QM G315026 showing the cortical palisade of tylostyles supported by the choanosomal tracts of styles. J. Stellate formations of tylostyles in the choanosome between the tracts of styles. K. Choanosomal styles. L. Tylostyles.