Ophiactis lymani Ljungman, 1872

Ophiactis lymani Ljungman, 1872 View in CoL

Ophiactis lymani View in CoL — Ljungman 1872: 629; Tommasi 1965: 5; 1970: 22, Fig.14 View FIGURE 14 ; 1999; Lima-Verde 1969: 11; Boffi 1969: 450; 1972: 319; Albuquerque 1986: 138, Fig. 23a–c View FIGURE 23 , est. VII, Fig. 2a–c View FIGURE 2 ; Monteiro 1987: 29, Est. Ie; 1997: 183; Tommasi & Aron 1987: 3; Manso 1993: 193; Pires-Vanin et al. 1997: 36; Capítoli; Monteiro 2000: 46; Morgado & Tanaka 2001: 177; Borges et al. 2002: 36, Fig. 21A–B View FIGURE 21 ; Borges et al. 2004: 157; Capítoli & Benvenuti 2004; Neto et al. 2005: 213; Borges & Amaral 2005: 249, Fig. A–D; Magalhães et al. 2005:63; Borges 2006: 57, Fig. 1.17 View FIGURE 1 ; Ventura et al. 2006: 351; Ventura & Veríssimo 2007c: 239, Fig. A–D; Neves et al. 2007: 1265; Gondim et al. 2008: 154; Majer 2008; Manso et al. 2008: 187, Fig. 14a,b View FIGURE 14 ; Lima & Fernandes 2009: 61; Barboza 2010: 15; Oliveira et al. 2010: 5; Lima et al. 2011: 6, Fig. 4B View FIGURE 4 ; Barboza & Borges 2012: 9; Miranda et al. 2012: 139; Gondim et al. 2013a: 513, Fig. 4G–H View FIGURE 4 ; Paim et al. 2015: 9, Fig. 6A–C View FIGURE 6 ; Alitto et al. 2016: 12, Fig. 5E–F View FIGURE 5 ; Souto & Martins 2017: 306; Bueno et al. 2018: 217, Fig. 58.

Material examined: Barra de Mamanguape reefs, Rio Tinto, PB: 6°45'49.35"S 34°55'4.85"W, 1 spec. ( UFPB /ECH– 2477). Bessa Beach, João Pessoa, PB: 7º04'33.0"S 34º49'30.0"W, 2 spec. ( UFPB /ECH–2459). Praia de Carapibus, Conde, PB: 7°17'59.0"S 34°47'54.0"W, 1 spec. ( UFPB /ECH–2460); 1 spec. ( UFPB /ECH–2461) GoogleMaps .

Description: specimen UFPB/ECH–2460. Circular disc ( dd = 1.42 mm and dh = 0.46 mm), convex, dorsally covered by large, irregular, overlapping scales, the largest are at the center of the disc ( Figs 17A, B View FIGURE 17 ). Triangular radial shield, longer than wide, separated by two large scales, the most internal triangular ( Fig. 17B View FIGURE 17 ). Ventral interradial region with scales smaller than the dorsal ones. Bursal slits extend from the second ventral arm plate (VAP) ( Fig. 17C View FIGURE 17 ). Jaw with diamond shape oral shield, tapered proximal edge, and rounded distally. Large triangular adoral shield, with an expanded lateral edge, that almost touch. Spatulate adoral shield spine, rectangular infradental papillae ( Fig. 17D View FIGURE 17 ). Six arms ( aw = 0.76 mm), about twice longer than the dd. Triangular dorsal arm plate, wider than long, with a tapered proximal edge and a straight distal ( Figs 17F View FIGURE 17 ; 18B View FIGURE 18 ). Pentagonal VAP, with the triangular proximal region ( Figs 17G View FIGURE 17 ; 18C View FIGURE 18 ), first ventral arm plate similar to VAP ( Fig. 17C View FIGURE 17 ). A single small triangular tentacle scale ( Fig. 17G View FIGURE 17 ). Three denticulated arm spine, ventral most arm spine smaller and sometimes modified in a hook, the medial large and the dorsalmost arm spine longest ( Figs 17F, G View FIGURE 17 ; 18G View FIGURE 18 ).

Microstructures: oral plate with abradial muscular area well defined, short radial channel ( Fig. 17E View FIGURE 17 ). Dental plate with an expanded distal region; the outer portion with two large tooth sockets, without perceivable protruding knobs and septum ( Fig. 18A View FIGURE 18 ). Lateral arm plate, convex in the proximal region ( Fig. 18D View FIGURE 18 ); inner portion with a single perforation ( Fig. 18E View FIGURE 18 ); outer portion with three spine articulations ( Fig. 18F View FIGURE 18 ). Vertebrae zygospondylous type: vertebra dorsal view with medial portion V-shape, slightly deep dorsal groove ( Fig. 18H View FIGURE 18 ); vertebra ventral view with narrow, elongated, and deep ventral groove, with several perforations ( Fig. 18I View FIGURE 18 ); vertebra proximal view ( Fig. 18J View FIGURE 18 ) with dorsal muscle area (Dma) larger than ventral muscle area (Vma) and vertebra distal view ( Fig. 18K View FIGURE 18 ) with Dma very united, while the Vma is very separated.

Intraspecific variations: in some specimens (UFPB/ECH–2459, dd = 0.90 mm) the spine in the ventral interradial disc portion was not observed, in others, it was possible to observe a small pointed spine. Disc coloration can vary from whitish to light gray ( Fig. 17A View FIGURE 17 ).

Taxonomic Comments: the species was also described with the ventral interradial region without pointed spines and a blunt spine in the indentation of the disc behind the radial shield (RS), like the example illustrated in the description ( Tommasi 1970). Delicate spines are sparse on the disc, ventral interradial region with smaller spines than the dorsal ones ( Paim et al. 2015). RS anteriorly separated by a triangular scale, sparse spines in the marginal region of the disc, behind the RS with two blunt spines. Ventral interradial surface covered by small scales and some smaller spines than the dorsal ones, and specimens were analyzed with five arms ( Borges et al. 2002). The projection of the proximal region of the dorsal arm plate is smoother and the vertebra ventral view with more large fossae ( Alitto et al. 2018).

Morphometric variations: a total five specimens were analyzed. Bigger dd: 1.42 mm, smaller dd: 0.79 mm. Average of dd = 1.15 mm with sd = 0.22 mm, dh = 0.38 mm with sd = 0.06 mm, aw = 0.50 mm with sd = 0.14 mm, and la = 2.17 mm with sd = 0.66 mm ( Table 8).

Substrate: the specimens were collected in algae, sediment and next to the Ophionereis reticulata , can also occur under rocks ( Paim et al. 2015), sponges, polychaetes ( Lima et al. 2011) and associated with the coral Carijoa riisei (Duchassaing & Michelotti 1860) ( Lima & Fernandes 2009) .

Bathymetric distribution: from the intertidal zone to 90 m ( Tommasi 1970).

Geographic distribution: Virginia, Bermuda, Tortugas, Tobago, Brazil, Cape Green, Gulf of Guinea ( Tommasi 1970). In Brazil: Maranhão ( Gondim et al. 2013b), Ceará ( Lima-Verde 1969), Paraíba in Cabo Branco Beach

( Gondim et al. 2008), Bessa, Carapibus, and Barra de Mamanguape reefs (present study), Pernambuco ( Lima & Fernandes 2009), Alagoas ( Lima et al. 2011; Miranda et al. 2012) and Bahia ( Magalhães et al. 2005; Manso et al. 2008; Paim et al. 2015; Souto & Martins 2017).