Parathyone itapuaensis Martins & Tavares 2021, sp. nov.
Creators: name: Martins, Luciana
name: Tavares, Marcos
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Echinodermata
Holothuroidea
Dendrochirotida
Cucumariidae
Parathyone
Parathyone itapuaensis

description: Parathyone itapuaensis sp. nov.
(Figures 1–4)
Type material. Holotype: 40 mm (MZUSP 2089), 12°57’ S; 38°21’ W, Itapuã beach, Salvador, Bahia, Brazil, L.R. Martins coll., 21.iv.2011, intertidal, found burrowed into soft sediments, underneath rocks. Paratypes: 1 spec 40 mm (UFBA 631), same data as holotype. 1 spec 40 mm (UFPB ECH 438), 07°04’ S; 34°49’ W, João Pessoa, Paraíba, Brazil. 1 spec 100 mm (MZUSP 2103), Ubatuba, São Paulo, Brazil. 5specs 10–25 mm (MZUSP 2756), 12°57’ S; 38°21’ W, Itapuã beach, Salvador, Bahia, Brazil. 5specs 10–25 mm (MZUSP 2756), 12°57’ S; 38°21’ W, Itapuã beach, Salvador, Bahia, Brazil.
Comparative material examined. Aslia pygmaea (Théel, 1886), 2 specs 50–70 mm (CASIZ 117956) [originally labeled as Ocnus pygmaeus], 13.viii.1977, intertidal, Venezuela. 1 spec 50 mm (USNM E 30519) [originally labeled as Ocnus pygmaeus], 29.iv.1981, 27m, Georgia, EUA. Parathyone braziliensis (Verrill, 1868), Praia da Figueira, São Sebastião, São Paulo, Brazil: 1 spec 70 mm long (MZUSP 1095), coll 14 October 1997. Ilha de Boipeba, Bahia, Brazil: 1 spec 40 mm (MZUSP 1207), coll 22 June 2015. Prado, Bahia, Brazil: 1 spec. 40 mm long (MZUSP 1147), coll 10 January 2015.Itapuã beach, Salvador, BA, Brazil, (12°57’ S; 38°21’ W), intertidal: 72 spec 10–60 mm long (UFBA 0180), coll 03 November 2006. Itapuã beach, Salvador, BA, Brazil, (12°57’ S; 38°21’ W), intertidal, 1 spec 35 mm long (MZUSP 1354), coll 05 April 2006. Itapuã beach, Salvador, BA, Brazil, (12°57’ S; 38°21’ W), intertidal, 24 spec 15–50 mm long (MZUSP 1143), coll 31 January 2015.Itapuã beach, Salvador, BA, Brazil (12°57’ S; 38°21’ W): intertidal, 3 spec 35–40 mm long (MZUSP 1383), coll 05 April 2008. Alagoas, Maceio, Brazil 1 spec 30 mm long (MZUSP 1100), coll 31 May 2011.Passo do Camaragibe, Alagoas, Maceio, Brazil. 3 spec 25–30 mm long (MZUSP 1094), coll 11 January 2011. MNHN-IE-2005 1237, 1238, 1239 [Slides of body wall and tentacles]. Parathyone surinamensis (Semper, 1867), 1 spec 40 mm (USNM E27248) [originally labeled as Ocnus surinamensis], 6.ii.1977, Limon Bay, Canal Zone, Panamá, Caribe. Parathyone suspecta (Ludwig, 1875), 2 specs 20–35 mm (USNM E22299) [originally labeled as Ocnus (Urodemella) suspectus, 28.ii.1966, Andros island, Bahamas. 1 spec 40 mm (ZBM – ECH 5687), Barbados. MNHN-IE-2005 3378, 33576 [Slides of body and tentacles].
Etymology. The specific name refers to the type locality: Itapuã.
Diagnosis. Length of anterior process (radial plate of the calcareous ring) larger than length of base of radial plate. Body wall buttons with triangular knobs; knobbed multiperforated plates in anal region. Two Polian vesicles and single madreporite.
Description. Body barrel-shaped to oval when fixed; tube feet scattered throughout body (Fig. 1a). Ten dendritic tentacles, ventral pair reduced (Fig. 1b). Anal papillae present (Fig. 1c) Longitudinal muscles well developed (Fig. 1d, e), split at anterior region (Fig. 1e). Retractor muscle short and attached to the middle of radial plate (Fig. 1g, i). Stone canal single, short, attached to round madreporite (Fig. 1g). Two Polian vesicle (Fig. 1h). Colour in ethanol brown
Plates of the calcareous ring lacking posterior processes. The radial and interradial plates of same height and laterally connected to each other for most of their length (Fig.1i). MidIR (IR5) is not modified (Fig.2b), and the midR (RI) is smaller than the other radials (Fig.2c). Radial and interradial plates with pointy anterior region and strongly concave at base (Fig.1 d–f). Anterior region of the radial plate slightly depression for attachment the RMA (Fig. 2d). AP close together, anterior notch small (Fig. 2d). Marginal grooves for AB deep, broad (Fig. 2d). GV at inner region of radial plates conspicuous (Fig. 2d). TCT X- to H-shaped (Fig. 2f). Size of radial plates varies; radial plates usually wider than interradial plates.
Body wall ossicles four holed-knobbed buttons with triangular knobs at the center (60–120 μm long, Fig. 3a–b; fig 4a–c); four-holed to multilocular shallow cups (35–45 μm long, Fig. 3c–d); knobbed perforated plates (60–100 μm long, Fig. 3e) at anal region. Introvert with shallow cups; knobbed in its inner and outer faces (30–40 μm long, Fig. 3f) and rosettes. Tentacles with three types of perforated rods: elongated with irregular margins (180–240 μm long, Fig. 3g); large arched rods (600–800 μm long, Fig. 3h) and knobbed curved rods at base of tentacles (60–180 μm long, Fig. 3i) sometimes tri-armed (300–400 μm long, Fig. 3j) and rosettes. Tube feet supporting rods with small perforations at extremities, one central perforation and one central apophysis (250–300 μm long, Fig 3k); end plate circular; small holes around margin, bigger ones centrally (100–140 μm long, Fig 3l).
Occurrence. Only known from Brazil (Paraiba, Bahia, and São Paulo).
Taxonomic Remarks. Parathyone itapuaensis sp. nov. is herein assigned to Parathyone, whose diagnostic characters (cf. Deichmann 1957) are recognized in the new species. They are as follow: 1) ambulacral feet stout spreading out into the interambulacral; 2) calcareous ring simple lacking posterior process; 3) dermal ossicles are baskets and knobbed buttons; tube feet with end plates and large supporting rods.
The new species shares with P. braziliensis and P. suspecta, two reduced ventral tentacles. However, differs from both, P. braziliensis and P. suspecta, in having the anterior process of the radial plate longer than the length of base of radial plate (vs anterior process of the radial plate as long as the base of the radial plate in P. braziliensis and P. suspecta). The new species further differs from P. braziliensis in that the anal region is provided with knobbed multiperforated plates (lacking in P. braziliensis) and in having two Polian vesicles (vs. one Polian vesicle in P. braziliensis).
Parathyone itapuaensis sp. nov. superficially resembles P. surinamensis in the general aspects of the calcareous ring. However, the new species stands apart from P. surinamensis in having the body wall buttons slightly knobbed and triangular knobs at the center (Fig. 4a–c); two Polian vesicle and the longitudinal muscle split anteriorly and in having tentacles with ventral pair reduced whereas P. surinamensis has body wall buttons strongly knobbed and rounded knobs at the center (Fig. 4d–f), one Polian vesicle; longitudinal muscle split before the midlength of the body cavity and in having tentacles of equal size.
Juveniles and adults of the same species can differ in the form of the ossicles (Cutress 1996). Also, ontogenetic changes in the form of the ossicles or even disappearance of the ossicles have been shown to occur, including in dendrochirotids (Vaney 1914; Thandar 1989; O’Loughlin and Alcook 2000; O’Loughlin et al. 2012; Martins 2019). However, in Parathyone itapuaensis sp. nov., the only difference found between adults and younger specimens was the number of ossicles, with the younger specimens tended to have more ossicles (stage of development based on size: 10–25mm in length).
description: Published as part of Martins, Luciana & Tavares, Marcos, 2021, A new species of Parathyone (Holothuroidea: Dendrochirotida: Cucumariidae) from northeastern Brazil, with a key to species, pp. 245-252 in Zootaxa 4985 (2) on pages 246-250, DOI: 10.11646/zootaxa.4985.2.7, http://zenodo.org/record/4943527