Pentamera, Ayres, 1852

Solis-Marin, Francisco Alonso, Alvarado, Juan Jose, Conejeros-Vargas, Carlos Andres & Caballero-Ochoa, Andrea Alejandra, 2020, Pentamera fonsecae n. sp. a new species of sea cucumber from the Pacific coast of Costa Rica (Holothuroidea: Dendrochirotida: Thyonidae), Zootaxa 4878 (3), pp. 581-588 : 586-587

Key to the Pentamera species from the Eastern Pacific (modified from Lambert 1998; Prata & Christoffersen 2016).

1 Tube feet with supporting tables......................................................................... 2

- Tube feet lacking supporting tables......................................... Pentamera chierchiae ( Ludwig, 1887)

2 Cylindrical form. Oval to elongated tables with four central holes and a short two-pillared spire table. Tube feet supporting tables with a tall spire.................................................................................. 3

- U-shaped to curved body form, podia in five bands. Circular to triangular tables, more than four central holes and a short to tall two-pillared spire. Tube feet supporting tables with a short to medium-size spire................................... 4

3 Mean length of body wall tables 50 to 99 μm; width of spire at base 25 to 49 μm. Temperate distribution (California, USA).................................................................... Pentamera charlottae Deichmann, 1938

- Mean length of body wall tables less than 50 μm; width of spire at base less than 25 μm. Tropical distribution ( Costa Rica)......................................................................... Pentamera beebei Deichmann, 1938

4 Moderate calcareous ring, oval tables with four central holes in the body wall..................................... 5

- Long calcareous ring, triangular, rounded or acorn-shaped tables with ladder-shaped spire in the body wall.............. 6

5 Small oval buttons with two central and up to eight marginal knobs in body wall, tentacles with round to oblong plates with perforations and knobs.............................................. Pentamera montereyensis Deichmann, 1938

- Body wall with thick oval, knobbed plates with meshwork of bumps covering one side, without buttons, tentacles with oblong reticulate plates...................................................... Pentamera trachyplaca (H.L. Clark, 1924)

6 Body wall without triangular ossicles..................................................................... 7

- Body wall with triangular ossicles........................................................................ 8

7 Crowded layer of acorn-like cups with two-pillared, tapering spire rising from a cup-shaped base.............................................................................................. Pentamera zacae Deichmann, 1938

- Without a crowded layer of acorn-like cups with two-pillared, tapering spire rising from a cup-shaped base.............. 9

8 Large, oval to triangular plates, rarely star-shaped tables, supporting tables with moderate spire, introvert with oval plates with serrated edge and blunt spines on surface.............................. Pentamera pseudocalcigera Deichmann, 1938

- Circular to triangular or star-shaped tables with a wide central spire, supporting tables with low bumpy spire, introvert with elongated to oval plates with numerous bumps and raised central holes.................. Pentamera rigida Lambert, 1998

9 Circular to oval tables, with smooth margin................................................................ 10

- Elongated tables, with wavy margin......................................... Pentamera constricta ( Ohshima, 1915)

10 Introvert with plates and/or rosettes...................................................................... 11

- Introvert with tables...................................................... Pentamera pediparva Lambert, 1998

11 Ossicles of body wall in one layer....................................................................... 12

- Ossicles of body wall in two layers....................................... Pentamera lissoplaca (H.L. Clark, 1924)

12 Tentacles with rosettes only................................................ Pentamera chiloensis ( Ludwig, 1887)

- Tentacles with plates only, or plates and rosettes............................................................ 13

13 Tentacles with elongated diamond-shaped plates with two large central holes, some with bumps or low pillar arch............................................................................. Pentamera populifera ( Stimpson, 1864)

- Tentacles with plates and rosettes....................................................................... 14

14 Ossicles of body wall with tables with stout spire (diameter of the disk 70–100 μm), ending in a few teeth............................................................................. Pentamera pseudopopulifera Deichmann, 1938

- Ossicles of body wall with tables with ladder-shaped spire (diameter of the disk 30–50 μm)...... Pentamera fonsecae n. sp.