Ophiophragmus luetkeni ( Ljungman, 1872 )

Alitto, Renata A. S., Bueno, Maristela L., Guilherme, Pablo D. B., Domenico, Maikon Di, Christensen, Ana Beardsley & Borges, Michela, 2018, Shallow-water brittle stars (Echinodermata: Ophiuroidea) from Araçá Bay (Southeastern Brazil), with spatial distribution considerations, Zootaxa 4405 (1), pp. 1-66 : 24-26

Ophiophragmus luetkeni ( Ljungman, 1872)

( Fig. 7 )

Type locality. Tortola, British Virgin Islands.

Maximum size. dd up to 9 mm (Barboza & Borges 2005).

Material examined. 2 specimens (dd: 5.7–9.1 mm) from intertidal: ZUEC OPH 2164, St. 48, 1 spm; ZUEC OPH 2346, St. 13H, 1 spm.

Description. Disc: (dd: 5.7 mm) circular or pentagonal, covered by numerous small and imbricating scales, approximately 20 between the centrodorsal and the edge of the disc. Radial shields as long as wide, separated by three scales. Fence of tapered papillae at the edge of the disc interradius ( Fig. 7A,C ). Ventral interradius covered with scales smaller than the dorsal and strongly imbricated. Bursal slits broad ( Fig. 7B ). Oral shields spearheadshaped, distally rounded, proximal angle acute, with lateroposterior indentations ( Fig. 7D ). Madreporite larger than other oral shields, but with similar shape and with pores distally ( Fig. 7E ). Adoral shields triangular, wider distally and united proximally. Two lateral oral papillae, distal slightly larger than the proximal. A pair of infradental papillae, well developed and rectangular ( Fig. 7D ).

Arms: dorsal arm plates semi-circular to rectangular, three times as wide as long, some fragmented, contiguous ( Fig. 7F,H ). Ventral arm plates pentagonal, twice as wide as long, distally straight and proximal angle acute, contiguous ( Fig. 7G,I ). Two tentacle scales on the proximal segments, one attached to ventral plate and one to lateral plate. Three pointed arm spines ( Fig. 7G ).

Lateral arm plates ( Fig. 7J,K ): general outline: ventral portion projecting ventro-proximalwards; ventro-distal tip not projecting ventralwards. Outer surface ornamentation: trabecular intersections protruding to form knobs approximately the same size as stereom pores. Outer proximal edge: surface lined by discernible band of different stereom structure, restricted to central part; without spurs; central part not protruding; surface without horizontal striations. Spine articulations: on same level as remaining outer surface; sizes all similar; distance between spine articulations increasing dorsalwards. Lobes simply separated, dorsal lobe clearly larger than the ventral lobe; lobes parallel, dorsalmost bent, and oriented nearly horizontal; stereom massive; sigmoidal fold absent. Inner side, ridges and knobs: dominated by two separate central knobs; without dorsal structure on inner side; single large perforation on inner side.

Vertebrae: zygospondylous of universal type and non-keeled. Proximal side of vertebrae dorsally without large groove on the dorsal-distal muscular fossae ( Fig. 7L ). Zygocondyles dorsalwards converging and zygosphene fused with pair of zygocondyles ( Fig. 7M ). Dorso-distal muscular fossae transformed distalwards projecting far from distal edge of zygocondyles ( Fig. 7N ). Zygosphene projecting beyond ventral edge of zygocondyles with projecting part longer than zygocondyles ( Fig. 7O ).

Taxonomic comments. Only two specimens of O. luetkeni were collected, one with a regenerating disc ( Fig. 7 ) and another without the disc. They were identified by comparing with descriptions in the literature ( Thomas 1962; Tommasi 1970; Borges & Amaral 2005), and with specimens from ZUEC OPH ( Ophiophragmus brachyactis , O. filograneus , O. pulcher and O. wurdemanii ). O. brachyactis differs from O. luetkeni in having two or three terminal hooks on the second arm spines. O. filograneus differs in having a disc with papillae on the ventral surface and bluntly rounded marginal disc papillae. O. pulcher differs in having arms banded with green, and a green or red stripe the length of the dorsal arm surface and O. wurdemanii differs in having arms banded with dark brown or black.

Remarks. Often only a few specimens of O. luetkeni are collected, possibly indicating it is not abundant ( Borges & Amaral 2005). It occurs in muddy, sandy and silt bottoms ( Clark 1918; Tommasi 1970; Borges & Amaral 2005; Manso et al. 2008). O. luetkeni was collected from very fine sand with corer.

Distribution. Tropical Atlantic (realm), Tropical Southwestern Atlantic (province): Northeastern and Eastern Brazil ( Manso et al. 2008; Correia & Sovierzoski 2013). Temperate South America (realm), Warm Temperate Southwestern Atlantic (province): Southeastern ( Tommasi 1970; Manso & Absalão 1988; Pires-Vanin et al. 1997; Netto et al. 2005; Oliveira et al. 2010; Pires-Vanin et al. 2014).

From intertidal to 50 m depth ( Alvarado & Solís-Marín 2013). The present study samples were collected in the intertidal.

Selected references. Ljungman (1872): p. 636 [as Amphipholis luetkeni ]; Tommasi (1970): p. 31, fig. 28, 29; Monteiro (1987): p. 88, est.Ve,f; Borges & Amaral (2005): p. 269, fig. a–d [as Ophiophragmus lutkeni ]; Manso et al. (2008): p. 193, fig. 19f,g [as Ophiophragmus luetkeni ].

Figures

FIGURE7. Ophiophragmus luetkeni ZUEC OPH 2164 (5.7 mm dd). (A) Dorsal view.(B) Ventral view.(C) Detail of fence of papillae. (D) Detail of the oral view. (E) Detail of madreporite. (F) Detail of dorsal arm. (G) Detail of ventral arm. (H) Dorsal arm plate. (I) Ventral arm plate. (J-K) Lateral arm plate. (L) Vertebra—proximal surface. (M) Vertebra—distal surface. (N) Vertebra—dorsal surface. (O) Vertebra—ventral surface. Abbreviations: ads: adoral shields; as: arm spine; bs: bursal slits; d: dorsal; dap: dorsal arm plate; ddi: dorso-distal; ddmf: dorso-distal muscular fossae; di: distal; dp: dorso-proximal; fp: fence of papillae; ip:infradental papillae; lop:lateral oral papillae; ma:madreporite; mp:madreporite pore; os:oral shields; p:proximal; pe: perforation; rs: radial shields; tn: tentacle notch; ts: tentacle scale; v: ventral; vap: ventral arm plate; vdi: ventro-distal; vp: ventro-proximal; zd: zygocondyle; zp: zygosphene. Stereomicroscope photos: (A)–(G), scale bar equal to 0.5 mm. SEM photos: (H)–(O), scale bar equal to 100 µm.