Rowedota chippiru Yamana & Tanaka & Nakachi 2017, sp. nov.
Creators: name: Yamana, Yusuke
name: Tanaka, Hayato
name: Nakachi, Shu
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Echinodermata
Holothuroidea
Apodida
Chiridotidae
Rowedota
Rowedota chippiru

description: Rowedota chippiru sp. nov.
(Figs 1B, 2B, 3B, 4B, 5B, 7)
Material examined. Holotype: WMNH-2015-INV- 1476 (ARA, 14 September 2015) (length 10.8 mm, width 0.8 mm). Paratypes: WMNH-2015-INV-1477 (ARA, 14 September 2015) (length 6.3 mm, width 0.5 mm); WMNH- 2015-INV-1478 (ARA, 14 September 2015) (length 3.6 mm, width 0.4 mm); WMNH-2015-INV-1479 (ARA, 14 September 2015) (length 9.2 mm, width 0.7 mm); WMNH- 2015-INV-1480 (ARA, 14 September 2015) (length 6.6 mm, width 0.6 mm).
Description. Body small, anaesthetized length of largest specimen (WMNH-2015-INV-1476) 10.8 mm (aπer preservation), cylindrical, slightly tapered toward posterior end (Fig. 1B, Table 1). Body colour (in preserved and living specimens) transparent white to greyish-pink. Mouth anterior; anus posterior. Oral disc inclined toward ventral side.
Ten tentacles non-retractile, slender, with bumpy skin. Each tentacle with one pair of digits; sensory cups absent (Fig. 2B). Colour of tentacles white to pink (in preserved specimens). Calcareous ring composed of five radial and five inter-radial plates, these all broad with distally flattened ginglymus ends (Fig. 3B). Polian vesicle single (Table 1). Stone canal undiscovered. Two long and unbranched tubules of ovaries; testis not observed. One ambiguous row of ciliated funnels situated in inter-radius of middle to posterior body cavity, near right side of mid-ventral longitudinal muscle.
Body wall containing wheel, sigmoid-hook, and thick-rod ossicles (Figs 4B, 5B, 7, Table 2). Wheel ossicles roundedhexagonal with six spokes. Inner margin of rim not parallel to outer margin, and rim narrower at corners. Teeth blunt, trapezoidal, 7–15 per radiant (means of 9–12 in different specimens), discontinuous at slight concavities of rim at corners. Spokes not broad, their breadth amounting to 11–21% of diameter (means 11–19%) (Fig. 7). Wheel ossicles scattered sparsely in ventral inter-radial body wall but clearly arranged in longitudinal row in anterior ventral region. Wheel ossicle aggregations (wheel papillae) absent. Wheel ossicle diameter varying widely even in same tissue sample: 44–109 µm (means 61–79 µm) in anterior dorsal side, 49–88µm (means 59–83 µm) in anterior ventral side, 45–86 µm (means 54–66 µm) in posterior dorsal side, and 46–87 µm (means 54–60 µm) in posterior ventral side. Wheel ossicle diameter in anterior dorsal side significantly different among five specimens (Kruskal-Wallis test, P <0.05) but not in other body wall parts among three fully checked specimens (Table 2). In two of latter specimens (WMNH-2015-INV-1477, -1479), wheel ossicle diameter significantly different among four body parts (Kruskal-Wallis test, P s<0.05), but not in third specimen (WMNH- 2015-INV-1480).
Sigmoid-hook ossicles thick and large, arranged in single rows in inter-radii along both sides of longitudinal muscles, with pointed end facing toward inter-radius and blunt end facing toward longitudinal muscles. Outer edge of bend with 2–5 minute teeth. Shank broadest at bend, suddenly narrower distal to bend. Shank length 71–110 µm (means 75–101 µm) in anterior dorsal side, 71–100 µm (means 76–92 µm) in anterior ventral side, 57–81 µm (means 66–77 µm) in posterior dorsal side, and 51–77 µm (means 55–72 µm) in posterior ventral side. Shank length significantly different among five specimens in anterior dorsal part and among three specimens in other parts (Kruskal-Wallis test, P s<0.05) (Table 2). Shank length significantly different among four body parts in two fully checked specimens (WMNH-2015-INV-1477, -1479) (Kruskal-Wallis test, P s<0.05), but not in other one (WMNH-2015-INV-1480).
Thick-rod ossicles arc-shaped, distally blunt, with approximately 10–40 minute verrucae, arranged between wheel ossicles and sigmoid-hook ossicles. Length of thick-rod ossicles 64–79 µm (means of 68–73 µm in different specimens) in anterior dorsal side, 55–79 µm (means 63–71 µm) in anterior ventral side, 51–57 µm (means 52–55 µm) in posterior dorsal side, and 47–59 µm (means 50–54 µm) in posterior ventral side. Length of thick-rod ossicles in anterior ventral side significantly different among three specimens (Kruskal-Wallis test, P <0.05) but not those of anterior dorsal side among five specimens and posterior ventral side among three specimens (Table 2); posterior dorsal side not analysed statistically as thick-rod ossicles very rare. Length of thick-rod ossicles in two fully checked specimens (WMNH- 2015-INV-1479, -1480) significantly different among four body wall parts (Kruskal-Wallis test, P s<0.01) (Table 2); other fully checked specimen (WMNH-2015-INV-1477) not analysed due to its near lack of thick-rod ossicles in posterior dorsal side.
Tentacles containing rod ossicles (Figs 5B, 7, Table 3), these spinous with low number of branches, length 41–78 µm, means 51–68 µm in five specimens, significantly different among them (Kruskal-Wallis test, P <0.01) (Table 3).
Distribution. In sand in lower intertidal zone of calm beach, Araha Beach, Okinawa Prefecture, southern Japan.
Etymology. The specific name chippiru, a noun in apposition, is derived from a Ryukyuan word for “something that is small”.
DNA barcode sequence. A 650bp sequence of the mitochondrial CO1 gene was obtained from a paratype specimen (WMNH-2015-INV-1479, GenBank accession number LC152967). Base frequency was A=16.3%, C=14.2%, G=24.2%, T=45.4%.
description: Published as part of Yamana, Yusuke, Tanaka, Hayato & Nakachi, Shu, 2017, Three New Shallow Species of Taeniogyrus and Rowedota (Echinodermata: Holothuroidea: Apodida: Chiridotidae: Taeniogyrinae) from Southern Japan, pp. 53-68 in Species Diversity 22 (1) on pages 55-57, DOI: 10.12782/sd.22_53, http://zenodo.org/record/4585067