Ophiothrix brasiliensis Santana, Manso, Almeida & Alves, 2020

Ophiothrix brasiliensis Santana, Manso, Almeida & Alves, 2020 View in CoL

Ophiothrix (Ophiothrix) angulata View in CoL — Tommasi 1970: 54–60; Viana 2010: 10–14, Fig. 2a–h View FIGURE 2 ; Gondim et al. 2013a: 67–68 View Cited Treatment , Fig. View FIGURE 2

2f–j; Gondim et al. 2013b: 514–515, Fig. 4a–b View FIGURE 4 . Ophiothrix ailsae View in CoL — Guille & Albuquerque 1987: 147; Albuquerque &

Guille 1991: 9. Ophiothrix angulate — Borges et al. 2002: 58–59, Fig. 34c–d; Borges et al. 2005: 65–66; Manso et al. 2008: 194, Fig. 21a–c View FIGURE 21 . Ophiothrix brachyactis — Oliveira et al. 2010: 8. Ophiothrix brasiliensis — Santana et al. 2020: 9, Fig. 6 View FIGURE 6 .

Material examined: Barra de Mamanguape reefs, Rio Tinto, PB: 6°45'49.35"S 34°55'4.85"W, 1 spec. ( UFPB / ECH–2478). Formosa Beach, Cabedelo, PB: 6º58'38.8"S 34º48'57.4"W, 2 spec. ( UFPB /ECH–2455) GoogleMaps .

Description: specimen UFPB/ECH–2455. Circular disc ( dd = 7.39 mm and dh = 2.20 mm), dorsally covered by small scales, from where bifid or trifid spines emerge; in the interradial region and in the radial shield (RS) the spines have two to six denticles ( Figs 23A View FIGURE 23 ; 24A, B View FIGURE 24 ). Large and triangular RS, occupying almost half of the dd, longer than wide, separated by elongated scales and by bundles of spines ( Fig. 23A View FIGURE 23 ). Ventral interradial region with scales similar to dorsal, spines with three to six denticles ( Fig. 23B View FIGURE 23 ). Wide and long bursal slits, extending to the fourth arm segment, with large genital plates at the base of the arms. Rounded madreporite ( Fig. 23B View FIGURE 23 ). Jaw with diamond-shaped oral shield, with a slightly tapered proximal edge, expanded, and rounded lateral edge ( Figs 23C, F View FIGURE 23 ). Narrow, triangular, and separated adoral shield, with tapered proximal edge and distal straight ( Figs 23C, G View FIGURE 23 ). Spaces between each hemimandible very evident. A medial column of abbreviated tooth papillae (TPa) flanked by columns of larger TPas ( Fig. 23C View FIGURE 23 ). Five Arms ( aw = 4.82 mm), about four times longer than the dd. Pentagonal dorsal arm plate, as long as wide, with a tapered proximal edge and slightly rounded distal edge ( Figs 23H View FIGURE 23 ; 24F View FIGURE 24 ). Rectangular ventral arm plate, with a concave distal edge ( Figs 23I View FIGURE 23 ; 24G View FIGURE 24 ); square first ventral arm plate ( FiG. 23C View FIGURE 23 ). A small and triangular tentacle scale ( Fig. 23I View FIGURE 23 ). Proximal lateral arm plate with eight to ten arm spines and six to eight distal, arm spine with a crown of denticles at the apex, the last spine modified into a hook ( Figs 23H, I View FIGURE 23 ; 24K View FIGURE 24 ).

Microstructures: oral plate longer than wide, abradial muscular area well defined, with rib-like branching structures, and long radial channel ( Fig. 23D View FIGURE 23 ); adradial joint area with narrow and striated muscle insertion area; large dorsal tentacle compartment and ventral tentacle compartment ( Fig. 23E View FIGURE 23 ). Dental plate with six tooth sockets (Ts) in the proximal region of the plate, that gradually decrease in size, with protruding knobs from the sides of Ts and separated by narrow septum; also, another five smaller sockets of tooth papillae are present in the distal lateral region of the plate ( Figs 24C, D View FIGURE 24 ), teeth as long as wide, smooth and short distal surface ( Fig. 24E View FIGURE 24 ). Lateral arm plate, convex in the proximal region ( Fig. 24H View FIGURE 24 ); inner portion with a single large perforation positioned near the end of the plate ( Fig. 24I View FIGURE 24 ); outer portion with six spine articulations ( Fig. 24J View FIGURE 24 ). Vertebrae zygospondylous type: vertebra dorsal view with a middle portion Y-shaped, slightly deep dorsal groove ( Fig. 24L View FIGURE 24 ); vertebra ventral view with wide, elongated, and deep ventral groove ( Fig. 24M View FIGURE 24 ); vertebra proximal view ( Fig. 24N View FIGURE 24 ) and distal view ( Fig. 24O View FIGURE 24 ) with dorsal muscle area much larger than ventral muscle area.

Intraspecific variations: the youngest specimen shows a violet dorsal disc. Dorsal and ventral disc whitish, with dorsal arm plate violet in color ( Figs 23A, H View FIGURE 23 ).

Taxonomic comments: the species was described with dorsal surface covered by small rounded and imbricated scales that support short and hyaline spines, with two to six thorns in the apex, circular oral shield, lateral arm plate cover part of the dorsal surface of the arm, with eight to ten arm spine proximally and six to eight distally, and vertebra ventral view with more large fossaes ( Santana et al. 2020).

Morphometric variations: a total of three specimens were analyzed. Bigger dd: 7.39 mm, smaller dd: 3.67 mm. The general average dd = 5.61 mm with sd = 1.86 mm, dh = 1.73 mm with sd = 0.42 mm, aw = 3.43 mm with sd = 1.21 mm and la = 23.69 mm with sd = 5.62 mm ( Table 11).

Substrates: the specimens were collected under rhodoliths.

Bathymetric distribution: possibly found at similar depth to Ophiothrix ( Ophiothrix) angulata , from the intertidal zone to 540 m of depth since they were previously identified as a single species ( Santana et al. 2020). More surveys are needed to verify that its bathymetry really corresponds to that Ophiothrix (Ophiothrix) angulata .

Geographic distribution: Pará, Maranhão, Piauí, Ceará, Rio Grande do Norte, Paraíba (Formosa Beach and Barra de Mamanguape reefs), Pernambuco, Alagoas, Bahia, Espírito Santo, Rio de Janeiro, São Paulo, Paraná, Santa Catarina, and Rio Grande do Sul ( Santana et al. 2020, present study).