Euthyonidiella occidentalis ( 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 : 442-445

Euthyonidiella occidentalis ( Ludwig, 1875)

( Figure 20 )

Thyonidium occidentale Ludwig, 1875: 119 .

Phyllophorus occidentalis: Deichmann 1930: 148 , pl. XVIII, figs 1–2.

Euthyonidium occidentalis: Deichmann 1938: 380 ; Deichmann 1941: 124.

Phyllophorus (Urodemella) occidentalis: Heding & Panning 1954: 164–165 , fig. 76; Domantay 1958: 191; Tommasi 1969: 10; Magalhães et al. 2005: 63; Miranda et al. 2012: 140.

Euthyonidiella dentata Cherbonnier, 1961: 612–613 , figs 1a–r; Tommasi 1969: 10, fig. 11; Mondin 1973: 8–9, fig. 5.

Euthyonidiella occidentalis: Martins & Souto 2015: 362–374 , figs 1–4; Prata & Christoferssen 2017: 54, fig. 2h; Prata et al. 2017: 6–7, figs 8c–i.

Material examined. Rio Grande do Norte State, Brazil: 1 spec., Búzios Beach , Nísia Floresta ( UFPB.ECH-2027), 1 spec., Búzios Beach, Nísia Floresta ( UFPB.ECH-1994). Paraíba State, Brazil: 1 spec., Ponta do Seixas, João Pessoa, ( UFPB.ECH-2105); 1 spec., 703’50”S; 3447’19”W ( UFPB.ECH-2106); 1 spec., 701’02”S; 3447’55”W, ( UFPB.ECH-2108); 1 spec., 0704’24.4”S; 3447’49”W ( UFPB.ECH-2109); 2 spec., Ponta do Seixas, João Pessoa ( UFPB.ECH-2110); 1 spec., Cabo Branco Beach, João Pessoa ( UFPB.ECH-2112); 1 spec., 706’59”S; 3446’04”W

( UFPB.ECH-2067); 1 spec., 0703’51”S; 3449’51”W ( UFPB.ECH-2063); 1 spec., 707’00”S; 3443’54”W ( UFPB. ECH-2041); 1 spec., 706’59”S; 3446’04”W ( UFPB.ECH-2018); 1 spec., Cabo Branco Beach, João Pessoa ( UFPB. ECH-2029), 1 spec., Cabo Branco Beach, João Pessoa ( UFPB.ECH-2023), 1 spec., Cabo Branco Beach, João Pessoa ( UFPB.ECH-2020), 1 spec., Cabo Branco Beach, João Pessoa ( UFPB.ECH-1996), 1 spec., Cabo Branco Beach, João Pessoa ( UFPB.ECH-1064), 1 spec., Cabo Branco Beach, João Pessoa ( UFPB.ECH-866), 1 spec., Cabo Branco Beach, João Pessoa ( UFPB.ECH-855), 1 spec., Cabo Branco Beach, João Pessoa ( UFPB.ECH-434), 1 spec., Cabo Branco Beach, João Pessoa ( UFPB.ECH-435), 1 spec., Cabo Branco Beach, João Pessoa ( UFPB.ECH- 1067); 1 spec., São Gonçalo Reef, João Pessoa ( UFPB.ECH-1608); 1 spec., Maceiozinho Beach, Jacum, Conde ( UFPB.ECH-1504); 2 spec., Areia Vermelha Reef, Cabedelo ( UFPB.ECH-1221); 1 spec., Barra de Camaratuba, Mataraca ( UFPB.ECH-1218); 1 spec., Reefs in front of Ponta de Campina, Poço Beach, Cabedelo ( UFPB.ECH- 1995); 2 spec., João Pessoa, 659’01”S; 3447’23”W ( UFPB.ECH-152); 1 spec., Pitimb Beach, Pitimb, 0728’01”S; 3448’47”W ( UFPB.ECH-2107). Pernambuco State, Brazil: 1 spec., Gaib Beach, Cabo ( UFPB.ECH-2018). Bahia State, Brazil: 2 spec., Pituba Beach, Salvador ( UFPB.ECH-2015); 3 spec., Itapo Beach, Salvador ( UFPB.ECH- 2028), 2 spec., Ponta de Aratuba, Itaparica ( UFPB.ECH-2111); 1 spec., South of Ilha Sueste, Abrolhos ( UFPB. ECH-2069); 1 spec., Ilha de Santa Bárbara (Portinho), Abrolhos (EQMN-1879).

Type locality. Surinam ( Deichmann 1930).

Description. Specimen UFPB.ECH-1064. Cylindrical body, curved, narrow in both ends, 6 cm in length, 2 cm in breadth in middle of body ( Fig. 20A ). Thin skin, smooth. Color light brown, with tube-feet yellowish in life, and whitish in alcohol. Mouth and anus directed upwards. Tentacles 20, bushy, similar in size ( Fig. 20C ). Introvert short. Tube-feet small, distributed in double rows in the radii and numerous in the interradii, more abundant ventrally. Calcareous ring complex, with radial plates and posterior processes divided into two pieces ( Fig. 20B ). Radial plates with a short indentation anteriorly, posterior processes long, broken in the specimen. Interradial triangular plates, anterior part pointed, with two lobes that slightly cover the initial part of the posterior processes of the radial plates. Madreporite rounded, stone canal long. Two balloon-shaped Polian vesicles, one smaller. Retractor muscles large, about 1/3 of body length. Longitudinal muscles thin. Respiratory trees with short branches. Gonad in single tuft, tubules numerous, elongated, branched once or twice. Body wall ossicles include tables with dentate margins (40 µm long, 20 µm high), four large central holes and some lateral, about three on each side, the two more central bigger than the others ( Figs. 20 J–K). Spire two-pillared, ending in three teeth. Tables from dorsal side with disc ends more pronounced. Body wall table disc from ventral side with eight or more holes, and three or more spines on each side of the margin. Tube feet with supporting plates (40 µm long) ( Fig. 20L ), supporting rods (100 µm long) ( Fig. 20N ), and endplates (250 µm long) ( Fig. 20M ). Introvert with rosettes ( Fig. 20G ), rods (100 µm long) ( Fig. 20I ) and tables (60 µm long) ( Fig. 20H ). Tentacles have rosettes (30 µm long) ( Fig. 20D ), rods (40 µm long) ( Fig. 20E ) and tables (50 µm long) ( Fig. 20F ).

Morphological variations. A total of 40 specimens were analyzed, the size varied from 6.5–20 mm in length, 2.5–23 mm in breadth in middle of body, 1.5–7 mm in breadth in anterior end, and 0.5–4.5 mm in breadth in posterior end. The body varied from cylindrical to barrel shape, probably due to the way they were fixed after collection, leaving the body more contracted. The tube feet are numerous, scattered in the interradii, in some specimens the radii are difficult to distinguish. The color in life varied among shades of yellow, orange, green, gray and dark brown. In alcohol, the color varied from brown to white. Young specimens have a translucent tegument and are usually found in algae.

Geographical distribution. Florida, Puerto Rico, Antilles, Aruba, Trinidad, Surinam, and Brazil ( Hendler et al. 1995). In Brazil, the species was recorded from Cear to Rio de Janeiro ( Martins & Souto 2015). It is found from the intertidal zone down to 99 m in depth ( Miller & Pawson 1984). In the Northeast coast of Brazil the specimens were found from the intertidal zone to depths of 20 m.

Remarks. This species was known as Phyllophorus (Urodemella) occidentalis and was recently synonymized with the genus Euthyonidiella in Martins & Souto (2015) . This genus has three species from the West Atlantic Ocean, Euthyonidiella occidentalis , Euthyonidiella arenicola Pawson & Miller, 1992 and Euthyonidiella trita ( Sluiter, 1910) . Both E. occidentalis and E. arenicola having similar color and body shape, but they differ by the form of the body wall ossicles. The tables of E. occidentalis are smaller and the pieces of calcareous ring have a flat or concave outer surface, without a trace of the longitudinal ridge ( Pawson & Miller 1992). Euthyonidiella occidentalis differs of Euthyonidiella trita ( Sluiter, 1910) by the calcareous ring morphology, number of tentacles, and shape of body wall tables.

Ecological note. The specimens analyzed were found associated with rhodoliths, buried in gravel and sand, under rocks, and in sandstone and reefs.

Figures

FIGURE 20. Euthyonidiella occidentalis (Ludwig, 1875), UFPB.ECH-1064. A, external view of animal; B, calcareous ring; C, tentacles; D, rosettes from tentacles, E, rods from tentacles; F, tables from tentacles; G, rosettes from introvert; H, tables from introvert; I, rod from introvert; J–K, tables from body wall; L, plate from tube feet; M, endplate; N, supporting rods from tube feet.