Thyone toyoshiomaruae Yamana, Ogawa & Ohtsuka, 2021

Yamana, Yusuke, Nakaguchi, Kazumitsu, Yamaguchi, Shuhei, Katoh, Mikio, Ogawa, Akito & Ohtsuka, Susumu, 2021, Four new dendrochirotid holothurians collected from the Seto Inland Sea and the western part of the Sea of Japan, western Japan, Zootaxa 5023 (1), pp. 1-43 : 18-30

publication ID

https://doi.org/ 10.11646/zootaxa.5023.1.1

publication LSID

lsid:zoobank.org:pub:E759FD85-1904-45A7-9A4D-56815FB9649B

persistent identifier

https://treatment.plazi.org/id/AD40CD45-4126-FFF3-FF02-FAA4F87BFD64

treatment provided by

Plazi

scientific name

Thyone toyoshiomaruae Yamana, Ogawa & Ohtsuka
status

sp. nov.

Thyone toyoshiomaruae Yamana, Ogawa & Ohtsuka View in CoL sp. nov.

[New Japanese name: Toyoshio-kehada-namako]

( Figs 2D View FIGURE 2 , 3D View FIGURE 3 , 7A–H View FIGURE 7 )

Material examined. Holotype, WMNH-INV-2015-2483 (ST- 11 in 2015, length 46 mm, width 7 mm, INSD accession number LC528686 View Materials , 514 bps, Fig. 2 View FIGURE 2 D-m) . Paratypes: WMNH-INV-2015-2484 (ST- 11 in 2015, anesthetized length 14 mm, width 2 mm, Fig. 2 View FIGURE 2 D-n); WMNH-INV-2015-2438 (ST- 3 in 2015, length 15 mm, width 4 mm, posterior only, Fig. 2 View FIGURE 2 D-k); WMNH-INV-2015-2439 (ST- 3 in 2015, length 7 mm, width 1 mm, Fig. 2 View FIGURE 2 D-l).

Diagnosis. Bodywalltable ossicles, with regular, oval disc with four large central perforations and small peripheral ones, low two-pillared spires with one crossbeam and 4–8 minute apical spines.

Description. Body medium, up to 46 mm, fusiform, curved, with both ends tapered and turned slightly upwards ( Fig. 2D View FIGURE 2 ); bodywall thick, soft. Living body color pale orange or pale olive-brownish, not seriously affected by fixation/preservation. Tentacles 10, arranged in a single circle, medioventral two tentacles smaller than the other eight. Live color of tentacles and introvert same as body in most parts. One row of short villi surrounding oral opening. Color of oral periphery and mouth brown. Pedicels minute, not retractile, covering entire body at constant density, lacking in introvert region. Color of pedicels same or slightly paler than adjacent body. Pedicels becoming gradually smaller anteriorly and posteriorly from middle portion of body. Ten anal papillae and five anal teeth on radii. After preservation in ethanol, color turned slightly paler than that of living state.

Table 7. Congeneric comparison of the morphologies amongst all the species of Massinium Samyn & Thandar, 2003

Tubular calcareous ring, with fragmented radial and interradial elements. Radial elements bifurcated posteriorly, approximately twice as long as inter-radials, posterior bifurcations of radial elements start after end of adjacent interradial elements ( Fig. 3D View FIGURE 3 ). Radials and inter-radials with anterior projections, each projection with terminal split; radial and interradial elements end with broad anterior piece, followed by usually 1–3 (mostly two) aligned rows of narrow pieces. One long Polian vesicle in medioventral, single stone canal in mediodorsal position. Wellmatured gonad situated in anterior mid-body, in two clumps, one on each side of dorsal mesentery, most tubules not branched. Gonad lacking ossicles.

Bodywall with abundant tables ( Fig. 7F, G View FIGURE 7 , Table 6), with oval disc and low, two-pillared spire, one crossbeam and 4–8 minute apical spines. Table disc with 4–9 (mostly 6-8) perforations, four large central ones and small peripheral ones.

Tentacles with rods, plates, and intermediate forms, varying in size and shape ( Fig. 7A View FIGURE 7 , Table 6). Some plates of complex shapes, occasionally possessing several free-branches, resulting in rosette-like forms. Peri-oral skin with small rosettes, with numerous short branches, and with regular tables adjacent to tentacle bases ( Fig. 7B View FIGURE 7 , Table 6). Tables with two pillars, mostly with 1–2 crossbeams, ending in 2–4 apical spines, occasionally the two pillars are united into one. Table disc oval with undulant margin, with four large central and 0–11 (mostly 4–5) small peripheral perforations. Pharyngeal villi with numerous, small, short, branching rosettes ( Fig. 7C View FIGURE 7 , Table 6). Introvert with tables and rosettes ( Fig. 7D View FIGURE 7 , Table 6). Tables with distorted, oval discs with undulating margins, with four large central, 4–12 (mostly 4–8) small peripheral perforations. Table with two, high pillars, mostly with two crossbeams and 2–8 minute apical spines, occasionally with low spires with only one crossbeam and rudimentary apical spines. Rosettes, medium size, with numerous, short branches.

Most pedicels with endplate and supporting tables ( Fig. 7E View FIGURE 7 , Table 6). Supporting table discs distorted, oval or rhomboidal, with unduling margin, weakly arced, with 2–4 large central and 2–8 small distal perforations. Supporting tables with two pillars with one crossbeam, ending in 4–8 minute processes. Endplate brittle, with approximately three rings of holes, viz., commarginally elongated holes near rim, radially elongated ones in mid-region, and almost circular ones in central area. Anal papilla with various shaped supporting plates ( Fig.7H View FIGURE 7 , Table 6). Skin around anus with regular tables, with distorted, oval discs with undulating margins, with four large central and 3-10 (mostly 4-8) small peripheral perforations, two pillars with one crossbeam, and 4–8 minute apical spines.

Remarks. Thyone toyoshiomaruae sp. nov. is most similar to T. villosa Semper, 1867 . Both species have thin, crowded pedicels that cover the entire body, an olive-brownish color, and one long Polian vesicle (Table 8). However the new species differs from T. villosa in its bodywall ossicles: T. villosa has table ossicles with single pillars, ending in one cluster of four or five minute apical spines ( Semper 1867 –1868; Panning 1949) (Table 8), whereas the new species, T. toyoshiomaruae , has table ossicles with two-pillars ending in two clusters of 2–4 minute apical spines. Tips of pillars in the new species are usually bifurcated and not fused into united single spire. The new species is also similar to T. papuensis (in Théel, 1886) (presently known as deichmannae ) in that their body ossicles possessing oval disc with low spire and four large central holes and small perforation at each corner, however the pedicel supporting tables of T. papuensis are unique form in their outline, supporting tables with rod-like disc ( Théel 1886) (Table 8). Additionally, the tentacles of T. papuensis have smooth rod ossicles only ( Liao & Pawson 2001), quite unlike the rods and plates of the present new species.

Distribution. The western part of the Sea of Japan, depth 78–87 m, on sand and muddy sand bottoms. Western part of the Sea of Japan, depth 87 m, sand bottom (ST- 11 in 2015) and depth 78 m, muddy sand bottom (ST- 3 in 2015).

Etymology. The specific name toyoshiomaruae alludes to the name TR/V TOYOSHIO MARU of Hiroshima University.

Molecular data comparison. In BLAST searches, the closest hit to the partial COI sequence is from Thyone pedata (INSD accession number KF142165 View Materials , NMV F173267, National Museum Victoria Australia, 83.0% similarity with 96% coverage). The results of BLAST searches supports that the present species belongs to Thyone .

TABLE 8-2. Congeneric comparison of the ossicles morphologies of bodywall and tentacles, amongst the presently nominated species of Thyone Oken, 1815 (Continued) TABLE 8-2. Congeneric comparison of the ossicles morphologies of bodywall and tentacles, amongst the presently nominated species of Thyone Oken, 1815 (Continued) TABLE 8-2. Congeneric comparison of the ossicles morphologies of bodywall and tentacles, amongst the presently nominated species of Thyone Oken, 1815 (Continued) TABLE 8-2. Congeneric comparison of the ossicles morphologies of bodywall and tentacles, amongst the presently nominated species of Thyone Oken, 1815 (Continued) TABLE 8-2. Congeneric comparison of the ossicles morphologies of bodywall and tentacles, amongst the presently nominated species of Thyone Oken, 1815 (Continued)

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