Pentamera fonsecae n. sp. a new species of sea cucumber from the Pacific coast of Costa Rica (Holothuroidea: Dendrochirotida: Thyonidae) Author Solis-Marin, Francisco Alonso Colección Nacional de Equinodermos “ Dra. Ma. Elena Caso Muñoz ”, Laboratorio de Sistemática y Ecología de Equinodermos, Instituto de Ciencias del Mar y Limnología (ICML), Universidad Nacional Autónoma de México (UNAM), Ciudad de México, C. P. 04510, México. fasolis @ cmarl. unam. mx; http: // orcid. org / 0000 - 0001 - 5729 - 3316 fasolis@cmarl.unam.mx Author Alvarado, Juan Jose Centro de Investigación en Ciencias del Mar y Limnología (CIMAR), Ciudad de la Investigación, Universidad de Costa Rica, San Pedro, 11501 - 2060 San José, Costa Rica. juan. alvarado @ ucr. ac. cr http: // orcid. org / 0000 - 0002 - 2620 - 9115 Author Conejeros-Vargas, Carlos Andres Posgrado en Ciencias del Mar y Limnología, UNAM, Av. Ciudad Universitaria 3000, C. P. 04510, Coyoacán, Ciudad de México, México. conejeros @ ciencias. unam. mx; http: // orcid. org / 0000 - 0003 - 0148 - 0475 conejeros@ciencias.unam.mx Author Caballero-Ochoa, Andrea Alejandra Facultad de Ciencias, UNAM, Circuito exterior s / n, Ciudad de México, C. P. 04510, México. & Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Ciudad de México, México. text Zootaxa 2020 2020-11-16 4878 3 581 588 journal article 8047 10.11646/zootaxa.4878.3.9 0df1cd40-d273-4ddb-9fd7-dca7fc392a8b 1175-5326 4425512 F91B145A-D220-4634-B13B-1B66514333BF 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.