Parathyone suspecta ( Ludwig, 1875 )

Prata, Jéssica, Manso, Cynthia Lara De Castro & Christoffersen, Martin Lindsey, 2020, Dendrochirotida (Echinodermata: Holothuroidea) from the northeastern coast of Brazil, Zootaxa 4755 (3), pp. 401-453 : 406-408

Parathyone suspecta ( Ludwig, 1875)

( Figures 2–3 )

Thyone suspecta: Ludwig, 1875: 16 , fig. 19; Lampert 1885: 157; Théel 1886: 133; Sluiter 1910: 338; Clark H.L. 1919: 63; Deichmann 1926: 23; Deichmann 1930: 175, pl. XVI, figs 3–4.

Ocnus suspectus: Miller & Pawson 1984: 393 ; Hendler et al. 1995: 262, figs 178e–j; Laguarda-Figueras et al. 2001: 32–33, fig. 12; Gondim et al. 2008: 154; Miranda et al. 2012: 141.

Parathyone suspecta: Deichmann 1957: 16 ; Deichmann 1963: 110; Prata & Christoffersen 2017: 51, fig. 1g.

Material examined. Rio Grande do Norte State, Brazil: 1 spec., Diogo Lopes , Macau, 0505’0.31”S; 3627’18.9”W ( UFPB.ECH-867); 11 spec., Diogo Lopes, Macau, 0504’46.9”S; 3626’19.5”W ( UFPB.ECH-868). Paraíba State, Brazil: 1 spec., Cabo Branco Beach, João Pessoa ( UFPB.ECH-1061); 1 spec., Cabo Branco Beach, João Pessoa ( UFPB.ECH-1499); 1 spec., Areia Vermelha Reef, Cabedelo ( UFPB.ECH-1216). Bahia State, Brazil: 1 spec., Barra Grande, Itaparica ( UFPB.ECH-2012).

Type locality. Barbados ( Deichmann 1930).

Description. Specimen UFPB.ECH-1061. Barrel-shaped body, 40 mm long, 20 mm in breadth in mid-body ( Fig. 2A ). Smooth and thick skin, color light brown with dark spots. Mouth and anus slightly upturned, five anal teeth present. Tentacles 10, very bushy, four most ventral reduced ( Fig. 2B ). Tube feet short, distributed in two rows in the radii and several rows in the interradii, more abundant ventrally. Calcareous ring simple formed by 10 pieces, with short posterior processes in radial plates, robust. Dorsal radial plate sub-rectangular, narrow anteriorly, at the point of attachment of the retractor muscles ( Fig. 2C ); dorsal interradial plates triangular, notched posteriorly ( Fig. 2D ). Ventral radial plate more elongated than dorsal, with bigger posterior processes ( Fig. 2E ); ventral interradial plates wider than that dorsal ( Fig. 2F ). Madreporite rounded, brain-like, stone canal spiraled. Polian vesicle single, elongated, balloon-shaped. Retractor muscles not thick, elongated, reaching half of the body. Longitudinal muscles thin, not divided. Respiratory trees thin, with short branches. Gonad in a single tuft, with tubules not branched, filling the cavity. Body wall ossicles consist of thick irregular knobbed buttons, some rectangular (60 µm long) ( Fig. 3G ); knobbed buttons of four holes, two central bigger; some knobbed buttons elongated, with six to eight holes ( Fig. 3H ); plates with four or more holes (70 µm long) ( Fig. 3I ); shallow baskets with four holes, some very knobbed, other baskets slightly shallow, with four holes and crown with about 10–12 spines (50 µm long) ( Fig. 3F ). Ossicles more numerous in the anterior region. Tube feet include irregular supporting rods (100 µm long) ( Fig. 3L ), irregular supporting plates with large holes (70 µm long) ( Fig. 3J ), and endplate (60 µm long) ( Fig. 3K ). Introvert with numerous small rosettes (40 µm long), baskets of four holes, some knobbed (40 µm long) ( Fig. 3E ) and knobbed buttons (50 µm long). Tentacles have small to large irregular rods (220 µm long) ( Fig. 3D ), elongated plates (70 µm long) ( Fig. 3C ), large to small rosettes (40 µm long) ( Fig. 3A ) and knobbed baskets of four holes (40 µm long) ( Fig. 3B ).

Morphological variations. A total of 16 specimens were analyzed, the size varied from 14–40 mm long and

5.5–20 mm wide in the middle, 2.5–8 mm wide in anterior end, and 1.5–2.5 mm wide in posterior end. The tentacles are 10, with two to four most ventral smaller, most species analyzed have four reduced tentacles. Young specimens show tube feet distributed in two distinct rows in the radii and few in the interradii. Plates and buttons are scarce in old specimens. According Deichmann (1930) Dendrochirotida species tend to reduce the ossicles throughout life.

Geographical distribution. Antilles, Colombia and Brazil ( Hendler et al. 1995). In Brazil, the species was recorded from Rio Grande do Norte to Bahia ( Tommasi 1969; present study). The bathymetric distribution is down to 60 m deep ( Martínez 1991). Here, the specimens were found only in the intertidal zone.

Remarks. The genus Parathyone was erected by Deichmann (1957) to accommodate the species with tube feet scattered over the body, simple calcareous ring and body wall with baskets and regular, strongly knobbed buttons/plates. Initially two species were transferred to this genus, Thyone suspecta and Thyone surinamensis ( Semper, 1867) . Parathyone suspecta differs from Parathyone surinamensis by the lack of equal tentacles and having relatively deep baskets. According to Deichmann (1930), the ossicles of P. surinamensis and P. suspecta are very variable.

Ecological note. This species was found between rocks, gravel and algae. Young specimens were found in association with algae.

Figures

FIGURE 2. Parathyone suspecta (Ludwig, 1875), UFPB.ECH-1061. A, external view of the animal; B, tentacles; C, dorsal view of the calcareous ring, detail of radial plate; D, dorsal view of the calcareous ring, detail of interradial plate; E, ventral view of the calcareous ring, detail of radial plate; F, ventral view of the calcareous ring, detail of interradial plate. Where, IRd = dorsal interradial plate; Rd = dorsal radial plate; IRv = ventral interradial plate; Rv = ventral radial plate; PA = point of attachment of the retractor muscles and notch for the passage of radial nerves.

FIGURE 3. Parathyone suspecta (Ludwig, 1875), UFPB.ECH-1061. A, rosette from tentacles; B, baskets from tentacles; C, elongated plate from tentacles; D, rods from tentacles; E, baskets from introvert; F, baskets from body wall; G, thick button from body wall; H, buttons from body wall; I, plates from body wall; J, supporting plates from tube feet; K, endplate; L, perforated supporting rod.