Neoamphicyclus Hickman, 1962

O’Loughlin, P. Mark, 2007, New cucumariid species from southern Australia (Echinodermata: Holothuroidea: Dendrochirotida: Cucumariidae), Memoirs of Museum Victoria 64, pp. 23-34 : 24-25

Neoamphicyclus Hickman, 1962

Neoamphicyclus Hickman, 1962: 58 .— Rowe, 1995: 275.

Diagnosis (emended). Dendrochirotid holothuroid genus, up to 60 mm long with maximum diameter 25 mm (preserved; tentacles excluded); sub-cylindrical form, elongate, narrowing anteriorly, tapering posteriorly to a narrowly rounded anal cone; 25 dendritic tentacles, irregularly grouped outer ring of 15 large, 5 irregularly grouped inner pairs small, total number and sizes variable, groups not aligned with radii; lacking collar of papillae around tentacle ring; tube feet on radii only, in 5 paired single series, paired zig-zag to double series in mid-body; radial tube feet present or absent across true introvert; calcareous ring not composite, lacks posterior prolongations; radial plates sub-rectangular, variable form in same specimen, commonly asymmetrical anteriorly, deep notch above muscle attachment, lateral shallow indentation, deep posterior notch, posterior projections not upturned; interradial plates almost as tall as radial plates, posteriorly wide with shallow indentation, tapering to point anteriorly; single dorsal stone canal and madreporite near vascular ring, rarely 2 or 3, small, madreporite with “split pea” form, less than 1 mm diameter; 1–3 ventral tubular polian vesicles; longitudinal muscles flat, undivided, retractor muscles branch from mid-body; tufts of gonad tubules on both sides of dorsal mesentery; respiratory trees extend coelom length.

Ossicles. Body wall and introvert with table disc ossicles only, with or without spires, sparse to numerous, predominantly irregular in form, pillars 2–5, predominantly 3. Tube feet with endplates, each with narrow rim of elongate perforated support plates, typically 2 large central perforations. Tentacles with irregular rods; variably with or lacking rosettes and tables. Posterior anal body wall with 5 rudimentary scale ossicles.

Type species. Neoamphicyclus lividus Hickman, 1962 (original designation).

Other species. N. altoffi sp. nov.; N. materiae sp. nov.; N. mutans ( Joshua, 1914) .

Distribution. Southern Australia: New South Wales (south of Bateman’s Bay), Tasmania, Victoria, South Australia, Western Australia (south of Abrolhos Is.); 0– 165 m.

Remarks. In describing his species and diagnosing his monotypic genus Hickman (1962) accurately observed that the table discs always lacked spires. This has been confirmed here by extensive sampling of specimens of Neoamphicyclus lividus from SE Tasmania. Specimens of a superficially similar species from N Tasmania, Victoria, South Australia and Western Australia have been determined in the past as N. lividus . However, in all of the many specimens sampled in this work most of the otherwise similar table discs have spires. Rowe (1982) and Marsh (1991) noted these spires. This has led to the recognition of a second allopatric Neoamphicyclus species ( N. materiae sp. nov. below). Cucumaria mutans Joshua, 1914 was reassigned to Cucumella Ludwig and Heding, 1935 by Heding and Panning, 1954, partly on the basis of having 20 tentacles. The syntypes and many specimens of C. mutans available for this study have 25 tentacles. C. mutans has all of the emended diagnostic characters of Neoamphicyclus Hickman, 1962 to which it is reassigned below. In fact one of the syntypes of C. mutans is Neoamphicyclus materiae sp. nov. (discussed below). Some specimens from across southern Australia, previously identified as Cucumella mutans , are recognized in this work as a 4th Neoamphicyclus species ( N. altoffi sp. nov., below). In the 4 species of Neoamphicyclus both the “true” introvert and part of the anterior body (“pseudo” introvert) may be withdrawn by the retractor muscles. This distinction between true and pseudo introvert is made in the descriptions. Radial tube feet are present on the pseudo introvert in all Neoamphicyclus species, but may be present or absent on the true introvert in the various species. The 165 m depth in the distribution range is taken from H.L. Clark (1946), but the specimen is not confirmed here as N. mutans ( Joshua, 1914) or N. altoffi sp. nov. (below) or N. materiae sp. nov. (below).