Delimitation of Ophioderma teres (Lyman, 1860) and Ophioderma unicolor H. L. Clark, 1940 stat. nov. (Echinodermata: Ophiuroidea), including the description of two new species Author Humara-Gil, Karla J. 8173990E-CA82-4B7C-BE3E-D31228CB51CD Laboratorio de Ecología Marina, Centro Universitario de la Costa, Universidad de Guadalajara, Puerto Vallarta, Mexico. k.humaragil@gmail.com Author Granja-Fernández, Rebeca 98B31C6C-C2FF-4BC2-A556-5782D3001A91 Postdoctoral researcher (CONAHCYT) associated with Programa de Maestría en Biosistemática y Manejo de Recursos Naturales y Agrícolas (BIMARENA) / Laboratorio de Ecología Molecular, Microbiología y Taxonomía (LEMITAX). Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Zapopan, Mexico. beckygranja@gmail.com Author Bautista-Guerrero, Eric 0C7DC2DA-EBB9-4998-9237-F7C7FC86B96F Laboratorio de Ecología Marina, Centro Universitario de la Costa, Universidad de Guadalajara, Puerto Vallarta, Mexico. eric.bautista0177@academicos.udg.mx Author Solís-Marín, Francisco A. A2417F0D-CA2A-4BE2-A6F0-C8991F4B90EA 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), Mexico City, Mexico. fasolis@cmarl.unam.mx Author Rodríguez-Troncoso, Alma P. B44F0417-F061-4B52-8AE6-190149FA2E41 Laboratorio de Ecología Marina, Centro Universitario de la Costa, Universidad de Guadalajara, Puerto Vallarta, Mexico. alma.rtroncoso@academicos.udg.mx text European Journal of Taxonomy 2024 2024-08-06 947 130 174 https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2625/12067 journal article 301866 10.5852/ejt.2024.947.2625 27dcea2b-bb85-4820-8073-deae02945f59 2118-9773 13310019 CBC9DA40-EC6D-4280-8BBC-6826D72A291E Key to the eastern Pacific species of Ophioderma This key serves as a reference for the identification of valid nominal species of Ophioderma in the EP. Before use, the following should be considered: 1) possible new undescribed species have been reported in the region, particularly in California, Baja California (Pacific side), and Clipperton Island ( Lessios & Hendler 2022 ). Caution should be used when employing this key to identify specimens from these locations; 2) some diagnostic characters vary according to size (e.g., granulation extent, fragmentation of DAPs, number of arm spines) ( Granja-Fernández et al. 2020 ; Stöhr et al. 2020 ; Humara-Gil et al. 2022 ). Therefore, small individuals (= younger) may not have developed all the characters included in the key. 1. Disc covered with flattened, brick-like granules ...................................... O. vansyoci Hendler, 1996 – Disc covered with rounded granules ................................................................................................. 2 2. Dorsal arm plates mostly or always entire ........................................................................................ 3 – Dorsal arm plates fragmented into two or more pieces .................................................................... 6 3. Dorsal arm plates mostly entire; a few can be divided into up to two pieces. Radial shields naked. Adoral shields covered with granules. Arms with transverse bands (in vivo and preserved) ............ ................................................................................................................ O . panamense Lütken, 1859 – Dorsal arm plates entire. Radial shields covered with granules. Adoral shields naked .................... 4 4. Distal genital slit with granule-bearing scales only. Disc olive green with dark pink or red (in vivo), or light brown (preserved); arms with olive green and dark pink/red (in vivo) or dark brown transverse bands (preserved) ................................................................................... O . variegatum Lütken, 1856 – Distal genital slit with naked and granule-bearing scales. Disc brown (preserved); arms with transverse bands (in vivo and preserved) .......................................................................................... 5 5. Disc dark brown with small white spots. Up to 11 arm spines ........................................................... .......................................................................................... O . hendleri Granja-Fernández et al. , 2020 – Disc orange (in vivo) or brown (preserved), with dark blotches. Up to six arm spines ..................... ..................................................................................................... O . pentacanthum H.L. Clark, 1917 6. Coloration uniform brown on disc and arms .................................................................................... 7 – Coloration with characteristic patterns on disc or arms .................................................................... 8 7. Distal genital slit with granule-bearing scales only .................................................. O . bichi sp. nov. – Distal genital slit with naked and granule-bearing scales ..... O . unicolor H.L. Clark, 1940 stat. nov. 8. Disc dark olive green to brown (in vivo), or dark gray to brown (preserved); arms with transverse bands (more subtle in preserved specimens) and parallel white bands in the median and distal arm sections .................................................................................... O . occultum Humara-Gil et al. , 2022 – Disc with specks or rings; arms without bands ................................................................................ 9 9. Disc dark brown with darker, sinuous rings on both dorsal and ventral sides. Radial shields naked ..................................................................................................................................... O . aija sp. nov. – Disc speckled. Radial shields covered or naked ............................................................................. 10 10. Granules present on the disc and the distal part of dorsal arm plates in the proximalmost and median arm sections .................................................................... O . peruanum Pineda-Enríquez et al. , 2013 – Granules limited to the disc and arm base ..................................................... O. teres ( Lyman, 1860 )