A New Species of Thyone (Echinodermata: Holothuroidea: Dendrochirotida: Phyllophoridae) from Wakayama, Japan Author Yamana, Yusuke Wakayama Prefectural Museum of Natural History, Funo 370 - 1, Kainan, Wakayama 642 - 0001, Japan E-mail: yamanamako @ gmail. com & Corresponding author yamanamako@gmail.com Author Hirai, Atsushi Susami Crustacean Aquarium, Esumi 808 - 1, Susami, Nishimuro, Wakayama 641 - 3142, Japan Author Hirashima, Kentarou Wakayama Prefectural Museum of Natural History, Funo 370 - 1, Kainan, Wakayama 642 - 0001, Japan E-mail: yamanamako @ gmail. com yamanamako@gmail.com text Species Diversity 2015 2015-11-25 20 141 151 journal article 10.12782/sd.20.2.141 2189-7301 5737583 78DD2363-D706-40C8-9F7D-2C9F2E116D55 Thyone susamiensis sp. nov. ( Figs 1–7 ) Material examined. Holotype , WMNH-2014-INV-2 (anaesthetized; length 127 mm , width 20 mm ). Paratypes : WMNH-2014-INV-1 (anaesthetized; length 111 mm , width 17 mm ); WMNH-2014-INV-3 (anaesthetized; length 121 mm , width 19 mm ); WMNH-2014-INV-4 (anaesthetized; length 94 mm , width 18 mm ); WMNH-2014-INV-5 (anaesthetized; length 74 mm , width 8 mm ); WMNH- 2014-INV-6 (unanaesthetized; length 54 mm , width 22 mm ); WMNH-2014-INV-7 (unanaesthetized; length 51 mm , width 9 mm ); WMNH-2014-INV-8 (unanaesthetized; length 71 mm , width 23 mm ); WMNH-2014-INV-9 (unanaesthetized; length 58 mm , width 25 mm ); WMNH- 2014-INV-10 (unanaesthetized; length 65 mm , width 22 mm ). All specimens from type locality; collection details given in Materials and Methods section above. Description. Appearance of anaesthetized specimens not drastically altered by fixation. General colour of specimens also not seriously affected by fixation/preservation ( Fig. 1A–C ). Body slightly curved or U-shaped, with both ends tapered and turned upwards; body wall soft and thin. Body whitish-yellow or cream, with blackish-purple marbling. Anterior and posterior ends with blackish-purple pigmentation in most specimens. Fig. 1. Thyone susamiensis sp. nov. , lateral views, A–C, WMNH-2014-INV-4 (paratype). A, B, Live specimen, before (A) and after (B) anaesthetization; C, fixed with anaesthesia; D, WMNH-2014-INV-2 (holotype), fixed with anaesthesia; E, WMNH-2014-INV-9 (paratype), fixed without anaesthesia, tentacles and introvert entirely retracted. Abbreviations indicate sites of tissue sampling for ossicle examination: aaa, anal appendage on abdominal-lateral side; aa, anterior part of body on abdominal side; am, middle part of body on abdominal side; ap, posterior part of body on abdominal side; da, anterior part of body on dorsal side; dm, middle part of body on dorsal side; dp, posterior part of body on dorsal side; ia, anterior part of introvert; im, middle part of introvert; ip, posteror part of introvert; ped, pedicel; ten, tentacle. Tentacles arranged in single circle; two tentacles on ventral side smaller ( Fig. 2A ). Colour of tentacles and introvert whitish-yellow or cream, and generally pigmented with brown or blackish-purple markings, occasionally variegated. Tentacle tips (nodules) tinged with brown or blackish-purple. Short processes present, surrounding entrance of oesophagus. Non-retractile pedicels covering entire body at constant density. On each side of narrow longitudinal muscles, pedicels forming ambiguous, contiguous row. Pedicels generally paler than adjacent body. Pedicels becoming gradually smaller anterior and posterior to those in middle portion of body, absent in introvert region ( Fig. 1B–D , Table 1 ). Pedicels blackish-purple on both ends of body in most speci- Fig. 2. Thyone susamiensis sp. nov. , A and B, WMNH-2014-INV-3 (paratype), front view of oral opening and circumoral tentacles (A), front view of anal opening and anal appendages (B). Abbreviations: ao, anal opening; ap, anal papilla; as, anal scale; ir, inter-radial tentacle; mvr, mid-ventral radial part; oo, oral opening; po, peri-oral part. Table 1. Summary of measurements and counts for 10 specimens of Thyone susamiensis sp. nov. Size of calcareous ring element in Type Body Gonad Body size abdominal-lateral side (mm) Counts No. a statusb statec stated Tentacles Length Width Length Width Length Width Body Introvert papillae scale canals vesicles 1 p a t 111 17 15.4 1.4 9.5 1.4>150 0 10 10 7 1 1 2 h a t 127 20 21.3 1.4 13.7 1.4>180 0 10 10 5 1 1 3 p a o 121 19 17.4 1.3 11.5 1.3>190 0 10 10 5 1 1 4 p a o 94 18 16.5 1.6 8.5 1.5>170 0 10 10 5 1 1 5 p a i 74 8 13.8 1.4 6.1 1.1>120 0 12 7 3 1 1 6 p u o 54 22 18.2 1.6 10.2 1.0? 0 10 10 5 1 1 7 p u i 51 9 13.4 1.0 6.0 1.0? 0 10 10 5 1 1 8 p u o 71 23 16.7 1.4 9.7 1.9? 0 10 10 5 2 1 9 p u o 58 25 18.5 1.5 9.8 1.2? 0 10 10 5 1 1 10 p u t 65 22 21.2 1.7 9.4 1.5? 0 10 10 5 2 1 a Registration No. Wakayama Prefectural Museum of Natural History , Invertebrate Collection of 2014 (WMNH-2014-INV-) . b p: paratype , h: holotype . c a: anaesthetized, u: unanaesthetized. d i: immature, o: ovarium, t: testis. e Number of pedicels in a row along to longitudinal muscle in abdominal side. mens. Ten anal papillae and five anal scales in most radii (five pairs of anal papillae in outer circle and five anal scales in inner circle; Fig. 2B , Table 1 ), generally pigmented brown or blackish-purple. Each anal scale containing a long calcareous structure. Base of anal scale connected to thin calcareous plate forming delicate calcareous ring surrounding anal region. Tubular composite calcareous ring present, encircling oesophagus. Pieces of radial and inter-radial elements forming mosaic pattern ( i.e. , not lined up). Radial elements bifurcate posteriorly, approximately twice as long as inter-radials, posterior forks of radial elements starting posterior to ends of adjacent inter-radial elements ( Fig. 3A, B , Table 1 ). Radials and inter-radials with sharp anterior projections; some projections on radials bifid at tip; anterior first piece of each radial and inter-radial element broad, pieces after that narrow, and usually aligned roughly in one to three (mostly two) longitudinal row. Most specimens ( n =8, including holotype ) with one Polian vesicle and one stone canal ( Table 1 ). Tubules of gonads unbranched. Fig. 3. Thyone susamiensis sp. nov. , elements of calcareous rings, viewed from body cavity. A, WMNH-2014-INV-7 (paratype); B, WMNH- 2014-INV-10 (paratype). Abbreviations: ie, inter-radial element; mvre, mid-ventral radial element; pb, posterior bifurcation; re, radial element. Table 2. Abundance (%) and size (µm) of ossicles from interradial tentacle of Thyone susamiensis sp. nov. (Fig. 4A, B).

Length	Widtha
%	Mean±sd	Mean±sd
( n )	(Range)	(Range)
WMNH-2014-INV-2
Rosettes and rodsb	100	62±25	20±11
(100)	(24–177)	(2–56)
WMNH-2014-INV-7
Rosettes and rodsb	100	61±19	18±8
(100)	(26–114)	(2–43)
WMNH-2014-INV-8
Rosettes and rodsb	100	78±36	17±10
(100)	(31–195)	(2–37)

Two types of ossicles found in tentacles, viz. , ‘rosettes’ and ‘rods’, as well as full series of intermediate forms; these ossicles, irrespective of form, with mean length and mean central width 61–78 µm and 17–20 µm (depending on specimen), respectively ( Fig. 4A, B , Table 2 ). Ossicle size not significantly different among three specimens examined (Kruskal-Wallis test, P s>0.05). a Width in the central part, not the maximam value. b Because it is difficult to draw a definite line of demarcation between rosettes and rods, both types were measured without distinguishing them. Two types of ossicles found in peri-oral skin: 1) ‘rosettes’, with mean length and mean central width 32–35µm and 19–21 µm (depending on specimen), respectively; size not significantly different among three specimens examined (Kruskal-Wallis test, P s>0.05); and 2) ‘tables’ with short spires and large discs, spires with two pillars and zero to two cross-beam connections, discs chiefly oval. Mean length and mean central width of discs 64–70 µm and 39–57 µm (depending on specimen), respectively ( Fig. 5A, B , Table 3 ); number of perforations in each disc 8–40, with mean of 18–27 holes (depending on specimen). Statistical analysis not applied to this type of ossicle, due to their very low frequency of occurrence. Fig. 4. Thyone susamiensis sp. nov. , ossicles of inter-radial tentacle on abdominal-lateral side. A, WMNH-2014-INV-7 (paratype); B, WMNH-2014-INV-8 (paratype). Single type of ossicle ( viz. , ‘small rosettes’) found in processes of oesophagus, mean length and mean central width 22–25 µm and 9–12 µm (depending on specimen), respectively ( Fig. 5A, B , Table 3 ). Measurements not different significantly among three examined specimens (Kruskal-Wallis test, P s>0.05). Single type of ossicle ( viz. , ‘rosettes’) found in introvert throughout its anterior, middle, and posterior parts; mean length and mean central width 31–39 µm and 21–27 µm (depending on specimen), respectively ( Fig. 5A, B , Table 3 ). These sizes not differing significantly among the three parts and three examined specimens (Kruskal-Wallis test, P s>0.05). Ossicles in posterior part not dense. Integument of body wall lacking ossicles throughout anterior, middle, and posterior parts, on both abdominal and dorsal sides. Pedicels displaying only one type of ossicle ( viz. , ‘endplates’). In middle part of abdominal side, diameter of endplates 117–195 µm (mean 149–180µm, depending on specimen) and approximately 47–144 holes (mean 81–123, depending on specimen) ( Fig. 6A, B , Table 4 ). Diameter of endplates significantly different among three specimens (Kruskal-Wallis test, P <0.01), smaller in smaller specimens. Approximately three different forms of hole arranged in three concentric areas on each endplate, viz. , latitudinally elongated holes near rim, longitudinally elongated holes in mid region, and almost circular holes in central area. Body-wall around anus lacking ossicles, except for fragments of calcareous plates surrounding anal region. Usually, anal appendages with one type of ossicle ( viz. , ‘rods’) in anal papillae ( Fig. 7A, B , Table 5 ), mean length and mean central width 91–96 µm and 4.4–6.3 µm (depending on specimen), respectively, not significantly different in size among three examined specimens (Kruskal-Wallis test, P s>0.05). Only one of these three specimens displaying, in low frequency, another type of ossicle ( viz. , ‘rosettes’) in anal appendages, with mean length of 39 µm and mean central width of 23 µm ( Fig. 7B , Table 5 ). Distribution. So far known only from type locality. Ecology. At the type locality, individuals of Thyone susamiensis were found burrowing in sand and pebbles that filled up spaces between boulders, often spreading their tentacles into the water (at least at night). We collected the following other species of sea cucumber nearby: Holothuria ( Lessonothuria ) pardalis Selenka, 1867 ; H. ( Mertensiothuria ) leucospilota Brandt, 1835 ; H. ( Platyperona ) sp.; Afrocucumis africana (Semper, 1867) ; Lipotrapeza sp. ; Polycheira sp. ; and Chiridota sp. Etymology. The specific name susamiensis is an adjective, derived from the type locality, Susami town.