Thyone brasiliana, Prata & Manso & Christoffersen, 2020

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 : 425-428

Thyone brasiliana sp. nov.

( Table 1 , Figures 13–14 )

urn:lsid:zoobank.org:act:1294BB74-2D96-420D-8732-5FA9DDB87B2D

Type material. Holotype: 1 spec., João Pessoa , Paraíba State, Brazil, 07º03’50”S; 34º47’19”W ( UFPB.ECH-2121) . Paratype: 1 spec., João Pessoa, Paraíba State, Brazil, 07º04’24.4”S; 34º47’49”W ( UFPB.ECH-2122).

Type locality. João Pessoa, Paraíba State, Brazil, 07º03’50”S; 34º47’19”W, at a depth of 10 m.

Etymology. The specific epithet brasiliana is used in reference to the country where the specimens were collected.

Diagnosis. Barrel-shaped body, slightly curved. Calcareous ring medium-sized, about 1/3 of total body length, radial and interradial plates united along the length, radial about three times smaller than interradial. Radial plates with posterior processes subdivided in five to seven pieces. Body wall with two-pillared tables, ending in four short teeth in the apex, disc oval, often with four holes. Tube feet with supporting tables of elongated disc with four central holes and two short pillars ending in three to four teeth, irregular supporting plates and endplate. Introvert with oblong tables two-pillared with several holes, ending in a crown of teeth that form a superstructure that can present small holes. Tentacles have small simple rods, large rods, rosettes and large elongated plates.

Description of holotype. Barrel-shaped body, slightly curved ( Fig. 13A ), 8.5 mm in length, 4 mm in breadth in mid-body. Slightly thickened skin, rough, with numerous ossicles. Color yellowish, with some brown spots in both ends, more numerous near the anus. Introvert whitish, tube feet and tentacles whitish with numerous brown spots. Color whitish in alcohol. Mouth upwards. Anus terminal, with five elongated anal teeth. Tentacles 10, bushy, retracted, two ventral ones reduced. Tube feet covering the body, arranged in double rows in the radii, with many tube feet scattered in the interradii. Calcareous ring tubular, fragile ( Fig. 13B ), about 1/3 of total body length, radial and interradial plates united along the length, radial about three times smaller than interradial. Radial plates notched anteriorly for the passage of the radial nerves and radial canal, with long posterior processes, subdivided in five to seven pieces; dorsal radial plates narrow and elongated; lateral and ventral radial plates wider than dorsal ( Fig. 13B ); the dorsal and ventral radial plates have anterior region narrower ( Figs. 13 C–D). Interradial plates arrowshaped, with an anterior depression, without posterior processes; dorsal interradial plates bigger than others ( Fig. 13B ); the lateral and ventral interradial plates smaller and slightly askew than dorsal ( Figs. 13 C–D). Madreporite rounded, stone canal elongated. Polian vesicle single. Retractor muscles thick, about 1/3 of body length. Longitudinal muscles thin, not divided. Respiratory trees a little branched, extending along the length of the body. Gonads in single tuft, tubules thin, numerous, unbranched. Body wall ossicles consist of two-pillared tables ending in four short teeth in the apex, disc oval, often with four holes, sometimes more (88–130 µm long; ± 40 µm high) ( Fig. 14E ). Tube feet include numerous supporting tables of elongated disc with four central holes, sometimes more holes near the ends (100–140 µm long, 40–60 µm high) ( Figs. 14 F–H), formed by two short pillars ending in three to four teeth ( Fig. 14G ), irregular supporting plates (± 100 µm long) ( Fig. 14I ) and endplates (± 180 µm long) ( Fig. 14J ). Introvert with oblong tables two-pillared with several holes, ending in a crown of teeth that form a superstructure that can present small holes (70–100 µm long, 30–40 µm high) ( Figs. 14 A–D). Tentacles include small simple rods (30–60 µm long), some with holes in both ends ( Fig. 13G ), large rods (± 150 µm long) ( Fig. 13H ), rosettes, some forming a second layer (30–60 µm long) ( Fig. 13F ) and large elongated plates (140–220 µm long) ( Fig. 13I ).

Paratype variation. The two specimens have similar features, including ossicles from body wall, introvert, tube feet and tentacles, and the arrangement of the tube feet. There are some differences in the calcareous ring that can be related to changes with growth ( Fig. 13E ).

Geographic distribution. The species is recorded for coordinates 07º03’50”S; 34º47’19”W, and 07º04’24.4”S; 34º47’49”W, João Pessoa, Paraíba State, Brazil. The species was found in depths from 6– 10 m.

Remarks. The new species is referred to Thyone Oken, 1815 by having diagnostic features of this group, as ten tentacles, tube feet scattered on body wall, not restricted to radii; calcareous ring tubular with posterior prolongations segmented in small pieces; both radial and interradial plates subdivided; body wall tables with four or more holes, 2-pillared, and introvert with tables.

Thyone brasiliana sp. nov. appears to be close to the species Thyone bidentata Deichmann, 1941 , from Gulf of California, when considered the presence of tables with multilocular disc in the introvert. However, the specimens analyzed present small to large rods and large elongated plates in tentacles, characters that are not mentioned for T. bidentata . In addition, they differ by the form of the calcareous ring and of the other ossicles.

The species of Thyone Oken, 1815 from the Western Atlantic are Thyone adinopoda Pawson & Miller, 1981 , Thyone crassidisca Pawson & Miller 1981 , Thyone deichmannae Madsen, 1941 , Thyone florianoi Martins & Tavares, 2018 , Thyone pawsoni Tommasi, 1972 , Thyone pseudofusus Deichmann, 1930 , Thyone tanyspiera Pawson & Miller, 1988 and Thyone waltinhoi Martins & Souto, 2018 .

Thyone adinopoda Pawson & Miller, 1981 differs from Thyone brasiliana sp. nov. by the morphology of the calcareous ring, presence of only rosettes in the introvert, for having body wall tables with tall spire, ending in a crown of four to seven teeth. Thyone crassidisca Pawson & Miller 1981 differs from Thyone brasiliana sp. nov. by the morphology of the calcareous ring, with plates formed by a mosaic of small pieces, besides the presence of rosettes in the introvert, and body wall tables with tall spire, ending in one tooth.

Thyone deichmannae Madsen, 1941 differs from Thyone brasiliana sp. nov. by the irregular and multilocular body wall table, with spire ending in a crown of teeth and introvert with tables and rosettes. Thyone brasiliana sp. nov. differs from Thyone florianoi Martins & Tavares, 2018 by the calcareous ring morphology, absence of rosettes in the introvert, short spire of the body wall tables, ending in four teeth, supporting tables from tube feet with short spire, ending in three to four teeth, and tentacles with rods, rosettes and plates.

Thyone brasiliana sp. nov. differs from Thyone pawsoni Tommasi, 1972 by the morphology of the calcareous ring, with interradial plates about three times bigger than interradial, the presence of a large crown of teeth in the apex of the introvert tables, with elongated disc, body wall tables with short spire, ending in four teeth. Thyone pseudofusus Deichmann, 1930 differs from Thyone brasiliana sp. nov. by the morphology of the calcareous ring, with interradial plates about two times bigger than radial, the presence of tables and rosettes in the introvert, short spire of the body wall tables, ending in a crown of teeth.

Thyone tanyspiera Pawson & Miller, 1988 differs from Thyone brasiliana sp. nov. by the morphology of the calcareous ring, with short interradial plates, similar at the radials in size, by the two kinds of body wall tables, oblong regular tables and irregular large cross-shaped tables, besides presence of only rosettes in the introvert. Thyone waltinhoi Martins & Souto, 2018 differs from Thyone brasiliana sp. nov. by the morphology of the calcareous ring, with bigger radial plates and interradial plates with short posterior processes, also differs by presence of rosettes in the introvert, regular body wall tables, with short spire, ending in a crown of teeth, and tentacles with only rosettes. A comparison between Atlantic Thyone species with Thyone brasiliana sp. nov. is given in table 1.

Ecological notes. The specimens were found in association with rhodoliths.

Figures

FIGURE 13. Thyone brasiliana sp. nov., UFPB.ECH-2121. A, external view of animal; B, dorsal view of calcareous ring; C, lateral view of the calcareous ring; D, ventral view of the calcareous ring; E, dorsal view of the calcareous ring from paratype (UFPB.ECH-2122); F, rosette from tentacles; G, small rod from tentacles; H, large rod from tentacles; I, large elongated plates from tentacles. Where, IRd = dorsal interradial plate; Rd = dorsal radial plate; IRL= lateral interradial plate; RL = lateral 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 14. Thyone brasiliana sp. nov., UFPB.ECH-2121. A, introvert tables; B–D, detail of the introvert table; E, body wall tables; F, supporting tables from tube feet; G, teeth detail of the tube feet table; H, supporting tables from tube feet; I, supporting plate from tube feet; J, endplate.