Psolidae Forbes 1841

Key to Australian species of Psolidae Forbes, 1841

1 Oral valves interradial if present; 10 tentacles............................................................... 2

- Oral valves radial; 15 tentacles.......................... Ceto cuvieria (Cuvier, 1817) (southern and western Australia)

2 Mid-body tube feet project through dorsal and lateral scales.................................................... 3

- Mid-body tube feet absent dorsally and laterally............................................................ 15

3 “Thorn” ossicles present in body wall and tentacles........................................................... 4

- Body wall and tentacles lacking “thorn ossicles”............................................................ 5

4 Mid-ventral radial series of tube feet present; buttons and rosettes present in dorsal and lateral ossicles, lacking spires on dorsal and lateral multi-layered ossicles; live and preserved colour “black”............................................................................................. Psolidium nigrescens H. L. Clark, 1938 (central New South Wales)

- Lacking mid-ventral radial series of tube feet; buttons and rosettes not present in dorsal and lateral ossicles, calcareous spires present on dorsal and lateral multi-layered ossicles; live and preserved colour not “black”................................................................................... Psolidium parmatum (Sluiter, 1901) (NW Australia slope)

5 Dorsal and lateral scales with spires/pillars (not lumps)........................................................ 6

- Dorsal and lateral scales lacking spires/pillars, some species with surface lumps on the scales......................... 7

6 Dorsal and lateral scales predominantly multi-layered ossicles, each with up to two thick, spinous spires, distally digitiform; lacking mid-ventral radial series of tube feet........................ Psolidium oloughlini sp. nov. (southern Australia)

- Dorsal and lateral scales lacking multi-layered ossicles, single-layered, thick, perforated plates with predominantly single, marginal, digitiform spires; mid-ventral radial series of tube feet present............................................................................................ Psolidium spinuliferum (H. L. Clark, 1938) (N and W Australia)

7 Body wall with cupped crosses and/or cups................................................................. 8

- Body wall lacking cupped crosses and/or cups.............................................................. 14

8 Cupped crosses and/or cups in sole of 2 size ranges........................................................... 9

- Cupped crosses and/or cups in sole of 1 size............................................................... 10

9 Rosettes present in dorsal body wall and tentacles; smaller cupped crosses and cups up to 32 μm long; sole with irregular thick perforated plates, knobbed on surface and margin........... Psolidium marshae O'Loughlin & Maric, 2008 (SW Australia)

- Rosettes absent from dorsal body wall and tentacles; smaller cupped crosses and cups up to 24 μm long; sole with smooth per-

forated plates............................................. Psolidium minutum (H.L. Clark, 1938) (E Tasman Sea) 10 Dorsal and lateral cups shallow, completely covered by fine spinelets, including the cross; lacking mid-ventral radial series of tube feet................................. Psolidium mccallumae O'Loughlin & Maric, 2008 (Western Australia slope)

- Dorsal and lateral cups and cupped crosses not shallow; spinelets on rim of cup or distally on branches of cupped cross, not on cross; mid-ventral radial series of tube feet present.......................................................... 11

11 Body wall with predominantly cups, fewer cupped crosses.................................................... 12

- Body wall with predominantly cupped crosses, fewer cups.................................................... 13

12 Knobbed plates in sole; tentacle rosettes small, up to 40 μm long; body rounded ventrally in transverse section............................................................ Psolidium berentsae O'Loughlin & Maric, 2008 (NE Queensland)

- Perforated plates in sole predominantly smooth; tentacle rosettes large, up to 80 μm long; body flat ventrally............................................................... Psolidium laperousazi O'Loughlin & Maric, 2008 (SE Australia)

13 Knobbed perforated plates in sole; irregular perforated plates in tentacles..................................................................................... Psolidium hutchingsae O'Loughlin & Maric, 2008 (N New South Wales)

- Perforated plates in sole predominantly smooth; tentacles lack irregular perforated plates............................................................................................ Psolidium ravum Hickman, 1962 (SE Australia)

14 Lacking series of mid-ventral radial tube feet; dorsal and lateral tube feet inconspicuous in mid-body; dorsal and lateral scales coarsely granuliform............................ Psolidium granuliferum H.L. Clark, 1938 (southern to SW Australia)

- Mid-ventral radial tube feet present as scattered series; dorsal and lateral tube feet conspicuous in mid-body; dorsal and lateral scales finely granuliform............................. Psolidium karenae O'Loughlin & Maric, 2008 (South Australia)

15 Dorsal and lateral scales microscopically smooth; digitiform oral scales interspersed with larger oral scales; very low, flattened profile............................................................ Psolus springthorpei sp. nov. (Queensland)

- Dorsal and lateral scales granuliform; lacking digitiform oral scales interspersed with larger oral scales or valves; low to domed profile....................................................................................... 16

16 Dorsal and lateral scales coarsely granuliform; either cups or half-cylinders present in dorsal ossicles.................. 17

- Dorsal and lateral scales finely granuliform; lacking either cups or half-cylinders in dorsal ossicles.................... 18

17 Macroscopically visible dome-like lumps on dorsal and lateral scales; half-cylinders present but lacking cups in dorsal ossicles................................ Psolus salottii sp. nov. (Great Australian Bight - South Australia to Macquarie Island)

- Macroscopically visible thick granules (not dome-like lumps) on dorsal and lateral scales; cups present but lacking half-cylinders in dorsal ossicles....................................................... Psolus steuarti sp. nov. (Victoria)

18 Little to no encroaching on oral valves by body wall scales; multi-layered ossicles and perforated plates present dorso-laterally, lacking bowl ossicles in sole........ Psolus antarcticus (Philippi, 1857) (Magellan Strait, Macquarie Island, South Georgia)

- Encroaching on oral valves by body wall scales; multi-layered ossicles only present dorso-laterally, bowl ossicles present in sole......................................................... Psolus parantarcticus sp. nov. (Macquarie Island)