Ophioderma hendleri sp. nov. urn:lsid:zoobank.org:act: 3455BEAC-DF5D-460A-89A8-A70B9A080BB4 Figs 1–4, 5 A–D; Table 1 Ophioderma sp. – Granja-Fernández et al. 2014: 135–137, fig. 7A–F; 2015a: 41–42; 2017: 172–175. Diagnosis Radial shields covered by granulation. Adoral shields naked, as long as broad. Up to 11 arm spines, dorsalmost the shortest and blunt, ventralmost the largest and robust. In vivo coloration, disc dark brown and mottled with small white spots, ventral margin beige and brown; arms dark brown with transverse white bands. Etymology This species is named after Dr. Gordon Hendler, an eminent ophiuroid taxonomist, curator of echinoderms at the Natural History Museum of Los Angeles County. Material examined Holotype MEXICO • 1 spec.; Chipehua, Oaxaca, 16°1´49.90˝ N, 95°21´33.70˝ W; 21 m; 5 Nov. 2011; R. Granja leg.; under rocks; ICML-UNAM 18315. Paratypes COSTA RICA • 6 specs; Coco Island; 19–28 Feb. 1994; Gordon Hendler leg.; MZUCR-ECH 321. MEXICO • 2 specs; Zacatoso, Ixtapa, Guerrero; 17°39´15.00˝ N, 101°37´19.00˝ W; 9.1 m; 1 Jun. 2012; R. Granja leg.; under rocks; ICML-UNAM 10582 • 1 spec.; Chahué, Oaxaca; 15°45´02.90˝ N, 96°07´23.43˝ W; 6.5 m; 14 Jan. 2017; R. Granja leg.; under rocks, 27°C; ICML-UNAM 18316 • 2 specs; Tijera, Oaxaca; 15°41´15.12˝ N, 96°26´31.47˝ W; 9 m; 29 Jan. 2016; D. Rangel and R. Granja leg.; under rocks, 27°C; ICML-UNAM 18317 • 1 spec.; Frente a Llano Grande, Oaxaca; 16°14´30.26˝ N, 98°27´04.64˝ W; 20 m; 1 Feb. 2016; Rebeca Granja leg.; sediment under rocks, 27°C; ICML-UNAM 18318 • 1 spec.; La Jeringa, Cacaluta Island, Oaxaca; 15°43´10.92˝ N, 96°09´39.91˝ W; 9–14 m; 26 Jan. 2016; D.Rangel and R. Granja leg.; sediment under rocks; ICML-UNAM 18319 • 2 specs; Punta Lobos, Espíritu Santo Island, Gulf of California; 24°28´29.06˝ N, 110°17´20.65˝ W; 15–17 m; 28 Oct. 2016; R. Granja leg.; under rocks, 28°C; ICML-UNAM 18320 • 3 specs; San Diego Norte, Gulf of California; 25°12´15.48˝ N, 110°41´41.64˝ W; 13 m; 29 Oct. 2016; R. Granja leg.; under rocks, 29°C; ICML- UNAM 18321 • 1 spec.; San Mateo Norte, Gulf of California; 25°22´43.54˝ N, 110°59´34.26˝ W; 12 m; 31 Oct. 2016; R. Granja leg.; under rocks, 29°C; ICML-UNAM 18322 • 10 specs; Isla San Diego, Gulf of California; 25°12´12.78˝ N, 110°41´40.14˝ W; 10–11 m; 31 Aug. 2008; F. Solís and Solís-Wolfowitz leg.; under rocks; ICML-UNAM 18323 • 5 specs; El Peruano, Guaymas, Sonora, Gulf of California; 27°54´30.06˝ N, 110°58´10.68˝ W; 12 m; 12 Aug. 2011; C. Sánchez leg.; under rocks, ICML-UNAM 18324 • 1 spec.; La Lobera, Bahía de La Paz, Gulf of California; 24°36´56.39˝ N, 110°24´00.57˝ W; 7 m; 2 Mar. 2010; F. Solís leg.; under rocks, ICML-UNAM 18325 • 1 spec.; Isla Larga (estación Este), Marietas Islands; 20°41´08.00˝ N, 105°34´00.00˝ W; 9 m; 22 Mar. 1996; F. Solís and C. Nepote leg.; under rocks; ICML-UNAM 18326 • 1 spec.; Los Islotes, Bahía de La Paz, Gulf of California; 24°35´00.00˝ N, 110°25´00.00˝ W; 18.3 m; 28 Apr. 1997; H. Cortés leg.; sediment under rocks; ICML-UNAM 18327. PANAMA • 2 specs; Panama; 24 Jun.–23 Jul. 1872; Hassler expedition leg.; MCZ OPH-116. Other material See: Supplementary material. Holotype description DD = 14.8 mm; 5 arms, AL = 69.1 mm. Disc flat, nearly circular. Dorsal disc densely covered by rounded, small granules, slightly separated from each other; granule density 113 mm-2. Granules at periphery of disc and on base of arms slightly larger than on central part of disc. Radial shields covered by granules (Fig. 1A). Interradii covered with granulation, similar to periphery and base of arms (Fig. 1B). Four genital slits in each interradius (Fig. 1B); proximal genital slits oval, in contact with distal part of oral shield and with 1 st LAP; distal genital slits rounded, elongated, placed between 5 th and 6 th arm segment and close to margin of disc, surrounded by granulation and numerous, elongated and imbricated scales next to side of lateral arm plates (Fig. 1B). Oral shields slightly broader than long, rounded triangular, with convex obtuse proximal angle, straight to convex distal edge, obtuse lateral angles. Madreporite with central, circular, shallow depression, located in distal part of oral shield. Adoral shields naked, as long as broad, triangular and completely separated from each other. Jaws bear 8–9 oral papillae on each side: LyOs small, 2 × as long as broad, angled upwards; AdShSp largest, rounded; 2°AdShSp elongated and narrow; LOPas 4–5 conical and pointed, slightly separated; IPa reduced, elongated and pointed; TPa pair at apex of jaw, elongated, robust and pointed, slightly separated. vT similar in shape and slightly larger than TPa. Four teeth: ventralmost broader than long, quadrangular but with rounded borders; dorsalmost pointed, slender and smallest. One OPRSp, large and pointed at each side, visible within buccal cavity. Granules covering oral plates and below adoral shields larger than those on dorsal disc and interradii (Fig. 1 C–D). Dorsal base of arms covered by granules and with approximately 11 oval scales, located laterally at first 3 dorsal arm plates (Fig. 1E). Dorsal arm plates 3 × broader than long, rectangular, overlapping; proximal edge straight, distal edge slightly concave with rounded lateral edges (Fig. 1F). Distalmost dorsal arm plates smaller, longer than broad, triangular. First ventral arm plate small, broader than long, with rounded edges; in contact with adoral shields. Second ventral arm plate quadrangular, as broad as long (Fig. 1C). Next ventral arm plates slightly longer than broad, quadrangular; proximal margin truncate and distal edge convex (Fig. 1G). Distalmost ventral arm plates wider distally, with a tapering proximal angle. Paired rounded depressions between most proximal ventral arm plates (Fig. 1B). LAPs conspicuous, semicircular, broader than long (Fig. 1H). LAP with up to 11 arm spines. First and 2 nd LAP with 3 arm spines; 3 rd with 4 arm spines; 4 th with 5; 5 th with 6; 6 th with 7; 7 th with 8; 8 th with 9; 9 th– 30 th arm plates with 10–11 arm spines; 35 th with 9 spines; 40 th– 50 th with 8; 60 th with 7; 70 th with 6; 75 th with 5; 80 th with 4;>80 th with 3 arm spines. Arm spines with blunt tip; length approximately ½ of LAP. Dorsalmost arm spine shortest, blunt; ventralmost arm spine longest and more robust, as long as 1 arm segment, almost in contact with tentacle scale of succeeding joint (Fig. 1H). Two tentacle scales; adradial tentacle scale ovoid, approximately ½× length of ventral arm plate; abradial tentacle scale slightly shorter, subtriangular (Fig. 1G). General coloration dark brown (dry specimen) (Fig. 1I). Dorsal side: disc dark brown and mottled with small white spots; middle of margin on each interradius of disc bearing white spot (Fig. 1A); arms dark brown with small black spots only observed microscopically and with every 5–6 arm plates with transverse white bands, located between distal part of ventral plate and proximal part of next arm plate (Fig. 1F, I). Ventral side: interradii, center and proximal part beige, margin dark brown with some beige marks (Fig. 1B). Jaw beige but oral shields can display brown color (Fig. 1C). Ventral arm plates beige, but that on tip of arms dark brown with some beige transversal lines (Fig. 1G). LAPs dark brown with some beige marks; arm spines dark brown and generally beige color on base and tip (Fig. 1H). Disarticulated ossicles Specimen analyzed: 1 spec., paratype ICML-UNAM 18323 (DD = 15 mm, AL = 80.8 mm). Radial shield (external view) irregularly triangular, with convex proximal margin, incised abradial edge with projection, convex to straight distal edge and irregular adradial edge, series of 8 pores on median to proximal margin (which are covered/overlapped by disc scales and granules in intact animal) (Fig. 2 A– B), most proximal ones deepest. Center of distal portion of radial shield covered in intact animal. Outer surface of stereom is open mesh of pores and small knobs (Fig. 2C). Dorsal arm plate slightly arched and somewhat rectangular, 3× as wide as long; proximal margin convex and distal margin straight, 1 spur on proximal portion of external surface (Fig. 2D). Ventral arm plate as long as wide, quadrangular with proximal side truncated and pointed spur, lateral sides concave forming border of tentacle pore (Fig. 2E). LAP D-shaped, 2× as high as wide, with 8 spine articulations sunken in notches of distal edge (Fig. 2 F–G). Ventral portion of LAP projecting ventro-proximalwards and ventro-distal tip projecting ventralwards (Fig 2F). Ventro-proximal margin with condyle (Fig. 2F). Proximal edge of LAP with 2 prominent and elongated spurs, protruding and modifying central-proximal edge (Fig. 2F), between spurs and across remaining proximal margin discernible band of different stereom structure (Fig. 2F). Outer surface finely meshed with relatively large polygonal knobs (Fig. 2I). Inner surface of LAP with continuous ridge on proximal edge, and at ventro-distal margin 2 spurs matching those on external surface (Fig. 2H), and 3 pores just below center. Spine articulations ventralwards increasing in size (Fig. 2G). Lobes with weak sigmoidal fold, tilted, curved, slightly joined on proximal margin by 3 or 4 knobs; ventral lobe smaller than dorsal lobe (Fig. 2J). Proximal vertebrae almost round, as wide as long, with large aboral muscle flange and smaller oral muscle flange (Fig. 2L). Distal face of vertebrae with large muscle flanges, with typical zygospondylous articulation (Fig. 2K). Tentacle scale longer than wide, with scale-like surface (Fig. 2M). Spines with scale-like surface and blunt tip (Fig. 2N). Dental plate consists of several pieces, 1 st piece bears 2 TPas on small round socket and 1 wide tooth socket, while rest of pieces with single tooth socket per piece (4 in total), none of sockets penetrate plate (Fig. 2O). Oral plates as long as high, abradial face with muscle fossa highly triangular, almost covering whole surface (Fig. 2P), adradial face in middle part with foot basin (Fig. 2Q). Paratype variations Large specimens showed some differences in morphology compared to small ones (Figs 1, 3–4). Large individuals have granules and scales on the base of the arms (Fig. 1E), but in the smallest specimens (DD = ~ 2–4 mm) the scales are covered by granules (Fig. 4B). The scales begin to appear as the animal grows; therefore, in specimens with DD = 4–6 mm there are up to 3 elongated scales to either side of the base of the arms (Fig. 3B), and with a DD = 7 mm there are up to six scales; the number of scales in larger specimens reaches 11 (Fig. 1E). Additionally, large individuals have numerous scales located on the distalmost part of the interradii (Fig. 1B) but in the smallest specimens (DD = 3–6 mm) these scales are not evident, and instead, only granules are present (Figs 3 F–G, 4F–G). In specimens larger than DD = 7 mm, a row of elongated scales in the distal genital slits is evident. Finally, in the smallest specimens the adoral shields are completely covered by granules, which disappear as the animal grows, and individuals with DD = 5 mm tend to have totally or partially covered adoral shields. Some specimens can have beige specks on the LAPs, the arm spines and the tentacle scales. Moreover, some specimens from the Gulf of California (Mexico) have a large white spot in the center of the dorsal disc. It is important to note that in vivo coloration (Fig. 5 A–D), generally conserved in all preserved specimens (Figs 1, 3–4), can be used as a distinctive character in the field. Habitat and distribution Widely distributed in the Eastern Tropical Pacific. Ophioderma hendleri sp. nov. has been collected in the Mexican Pacific from the Gulf of California (in the States of Sonora and Baja California Sur), Jalisco, Michoacán, Guerrero and Oaxaca as well as in Revillagigedo, Marías and Marietas Islands. In Costa Rica it has been collected from Murciélago, Caño, and Cocos Islands; in Panama from Pearl Islands; and finally, in Colombia from the localities La Parguera and La Roñosa Rock (see: Supplementary material). The northernmost locality of its distribution is off San Francisquito Bay (Gulf of California, Mexico; 28° N) and the southernmost point is La Roñosa Rock, Colombia (3° N). Due to its distribution, O. hendleri sp. nov. can be considered as a species with a Panamic affinity, suggesting that, similar to other ophiuroids (e.g., Ophiocoma aethiops Lütken, 1859 and Ophiocomella alexandri (Lyman, 1860)), its distribution may extend to northern Peru, where a transitional zone between the Panamic and the Peruvian Provinces is located (Granja-Fernández & Hooker 2020), but more sampling effort is needed to confirm its presence or absence in this area. The species inhabits depths between 0.40– 37 m. Ophioderma hendleri sp. nov. is mostly collected under rocks, burrowed in the sediment and it is common to find it associated with coral and rocky reefs (Granja-Fernández et al. 2014). Remarks Ophioderma hendleri sp. nov. is one the most widely distributed ophiodermatids in the Eastern Tropical Pacific and it is of interest to note that although it has been collected since 1936, it has been misidentified in all the reviewed collections as O. variegatum or O. panamense (see Discussion). In previous works, Granja-Fernández et al. (2014, 2015a, 2017) mentioned the presence of Ophioderma sp. 1, which actually corresponds to O. hendleri sp. nov.; therefore, these records are considered to be this species. In our revision of the specimens, we did not observe any differences in the morphological characters from different geographical areas, suggesting that intraspecific variation in O. hendleri sp. nov. is not related to its distribution. On the other hand, it is very notable that this species in most cases presents the same color pattern (dorsal side dark brown, ventral side beige and arms with transversal lines; Figs 1, 3–5), with some exceptions (see Paratype variations). This is in contrast to other Ophioderma species such as O. panamense or O. variegatum, which can display a great variety of colors (green, yellow, pink, etc.; Nielsen 1932; Ziesenhenne 1955). This species is commonly found at the same localities as O. panamense and other ophiuroids such as Ophiactis simplex (Le Conte, 1851), Ophiactis savignyi (Müller & Troshel, 1842), Ophiocoma aethiops, Ophiocomella alexandri, Ophionereis annulata (Le Conte, 1851), Ophiothela mirabilis Verrill, 1867 and Ophiothrix (Ophiothrix) spiculata Le Conte, 1851. It is one of the most conspicuous Ophioderma species of the Eastern Tropical Pacific and it is always hiding under small and medium-sized rocks and in sediment of median size of rocky and coral reefs (Fig. 5 A–B). Its abundance has not been quantified, but using scuba diving, in an hour of sampling effort of all the species of ophiuroids at one locality, a total of 5– 6 specimens were found, a smaller number compared to O. panamense (8– 12 specimens). It tends to be gregarious, and it is very common to find at least two specimens occupying the same space. Field notes denote that O. hendleri sp. nov. has been found in waters with a bottom temperature of 27–29°C.