Paracaudina bacillis O'Loughlin and Barmos 2011, sp. nov.

Paracaudina bacillis O’Loughlin and Barmos sp. nov.

Figures 5a–f, 6a–c Paracaudina sp. Rowe, 1982: 470, fig. 10.34c.

Paracaudina australis.—Gowlett–Holmes, 2008: 263. — Saunders, 2009: 99, fig. 5.19. (non Molpadia australis Semper, 1868)

Material examined. Holotype. Victoria, Westernport Bay, Phillip Island, Ventnor, McHaffie Point, MRG, 16 Feb 2008, NMV F151853.

Paratypes. Westernport Bay, San Remo, Griffith Point, 2 Jan 1999, NMV F89700 (1); Merricks beach, 5 Nov 1967, NMV F45254 (1); 27 Jul 1969, NMV F45240 (1); 4 Jun 2011, NMV F174893 (1); 10 Jun 2011, NMV F174894 (1); Shoreham, 26 Aug 1978, NMV F76071 (2); 30 Mar 1902, NMV F173250 (1) (removed from Shoreham lot 60669– 71 / H19 (3) examined in part by Joshua 1914).

Other material. Victoria, Westernport Bay, Crawfish Rock, 12 m, 13 Oct 1968, NMV F169343 (1); Somers, 28 Sep 1968, NMV F45273 (1); Port Phillip Bay, Brighton beach, NMV F45020 (1); Rosebud beach, NMV F173247 (1); Rye pier, 6 Apr 2011, NMV F173272 (1); Blairgowrie Marina, 5 m, 18 Jun 2011 (photo J. Finn, NMV); Tootgarook beach, 20 Jun 2011, NMV F174896 (1). South Australia, Yorke Peninsula, Browns Beach, SAM K2493 (6); Edithburgh, sand, 3–4 m, 12 May 1999, SAM K2486 (1); 2–3 m, 11 Jun 2005, SAM K2487 (1); sand, low tide, 26 Oct 2007 SAM K2490 (1); 8 Nov 2003, SAM K2491 (1). Western Australia, east of Duke of Orleans Bay, Niminup beach after storm, Nov 1990, WAM Z31888 (1); Albany, 5 Dec 1983, WAM Z31881 (1).

Diagnosis. Paracaudina species up to 180 mm total length, up 55 mm diameter, caudal taper 45 mm long (SAM K2491, preserved); thin, parchment-like to soft leathery body wall (preserved); live colour off-white, preserved colour off-white to pale yellow or brown; posterior body with caudal taper to narrow rounded end, sometimes short discrete tail, lacking a discrete long thin tail; body wall ossicles small irregular rods only, straight, bent, wavy, J-shaped, sometimes with nodes, rarely with short branches, up to 64 µm long.

Type locality. Victoria, Westernport Bay, Phillip Island, Ventnor, McHaffie Point.

Distribution. Victoria (Westernport Bay, Port Phillip Bay), South Australia Gulfs, Eyre Peninsula, to southern Western Australia (Albany); 0–145 m (Rowe 1982); 0–230 m (Gowlett– Holmes 2008).

Etymology. From the Latin baculus (rod), and its diminutive bacillus, referring to the very small rod ossicles only in the body wall.

Remarks. Paracaudina bacillis O’Loughlin and Barmos sp. nov. is distinguished diagnostically amongst Paracaudina species by having only small irregular rod ossicles in the body wall. Rods of similar form occur also in Paracaudina australis (Semper, 1868), a species that also has irregular marginally spinous perforated plate ossicles in the body wall. Rowe 1982 recognised this “undescribed form” from Port Phillip Bay and southern Western Australia, and illustrated (fig. 10.34c) the diagnostically characteristic minute irregular rod ossicles from the body wall. Gowlett–Holmes 2008 illustrated and described a species from southern Australia as Paracaudina australis that has the body form, size up to 20 cm long, and off-white colour of Paracaudina bacillis O’Loughlin and Barmos sp. nov. Gowlett–Holmes 2008 described the habit as “usually completely buried 5–10 cm below the sediment surface; moves slowly through the sand feeding on detritus, leaving a broad furrow-like trail”. Saunders 2009 also illustrated a specimen as P. australis at Coffin Bay on the Eyre Peninsula that we judge to be P. bacillis based on size and form and colour. Joshua 1914 referred two specimens from Westernport Bay and “Mordialloc” (Port Phillip Bay) to Caudina chilensis (Müller). We found these two specimens with a third specimen in lot H19 / 60669– 71 / NMV F45019, and assigned (below) the two referred to by Joshua 1914 to the new species Paracaudina cuprea O’Loughlin and Barmos (F169344) and Paracaudina tetrapora (H. L. Clark, 1914) (F45019, original registration). The label indicated all three specimens were collected by J. A. Kershaw at Shoreham. We judge that Joshua’s reference to “Mordialloc” was a mistake. We found no specimens from Mordialloc in the NMV collection. The third specimen in the lot, not commented on in Joshua 1914, is the third new species (above) Paracaudina bacillis O’Loughlin and Barmos (F173250).