Paradota plentyensis, Davey, 2014

Davey, Nicola, 2014, First record of genus Paradota Ludwig & Heding in New Zealand waters and description of a new species (Echinodermata: Holothuroidea: Synaptida), Memoirs of Museum Victoria 72, pp. 1-4 : 2-4

Paradota plentyensis sp. nov.

Zoobank LSID. http://zoobank.org/ urn:lsid:zoobank.org:act:

7F0984EC-E875-431F-9F58-5CF59A9BD0A2

Material examined. Holotype. New Zealand, Bay of Plenty, White Island: NIWA 87163 , Stn TAN1206/144, 37.53° S, 177.29° E, 1182 m, 28/04/2012 . Paratypes. NIWA 83152 (13 specimens); same station data as holotype .

Other material. New Zealand, Bay of Plenty, Tauranga Canyon: NIWA 82999 (1 specimen) Stn TAN1206/113, 37.25° S, 176.97° E, 1222 m, 25/04/2012 . Bay of Plenty, White Island: NIWA 83167 (1 specimen) Stn TAN1206/145, 37.52° S, 177.30° E, 918–1003 m, 28/04/2012 , NIWA 83224 (1 specimen) Stn TAN1206/152, 37.55° S, 177.27° E, 918–1003 m, 28/04/2012 . NIWA 87164 (2 specimens) Stn TAN1206/144, 37.53° S, 177.29° E, 1182 m, 28/04/2012 .

Description of holotype. Paradota species 20 mm long, 4 mm wide, 4 mm high (preserved). Body form long, cylindrical with slightly bulbous posterior end (possible preservation artefact), bulbous end skin is thinner than rest of the body. Skin contracted, covered in small papillae giving a granular texture. No tube feet. Mouth is terminal, surrounded by a tentacle crown with 12 equal sized tentacles of peltato-digitate shape with 4-5 digits per side of each tentacle, which become smaller nearer the tentacle trunk.

Paratypes follow the general description above with the following differences: specimens are up to 40 mm long, 4 mm wide and 4 mm high (preserved). The bulbous end can be either anteriorly or posteriorly located.

Due to the small size of specimens the paratypes were extensively dissected. Internally the majority of the coelomic cavity is occupied by sediment filled intestine. The longitudinal muscles are large, up to 2 mm high and wide, divided. One large (1.5 mm) polian vesicle (structure responsible for maintaining water vascular system pressure) is present with 2-3 smaller thinner ones. Gonads not visible in dissected specimens but tubule like strands present posteriorly which may be undeveloped gonad material. Calcareous ring consists of 12 large square pieces, radial and interradial pieces evenly sized, some radial pieces have a perforation in the upper part, posterior rim undulating.

The only ossicles present are in the tentacles and the longitudinal muscles. The body wall proper is completely devoid of ossicles. Ossicles of tentacles— smooth rods to slightly curved branched rods with varying degrees of branching distally: up to 70 µ m length and 15 µ m width. Ossicles of longitudinal muscles are miliary granules—smooth, oval, baton to rod-shaped: up 70 µ m length and 10 µ m width.

Colour. Deep purple (preserved and live)

Etymology. Named for the Bay of Plenty in the North Island of New Zealand as the type locality and presently the only known distribution for this species.

Distribution. New Zealand, Bay of Plenty, 918–1222 m.

Remarks. The lack of ossicles in the body wall and associated number of tentacles immediately indicated that we had encountered a new genus in New Zealand waters. There are three known genera within the Chiridotidae that are devoid of body wall ossicles: Achiridota Clark, 1908 which has 12 tentacles and is completely devoid of any ossicles; Kolostoneura Becher, 1909 which has 10 tentacles which do contain ossicles; Paradota with 12 tentacles and tentacle ossicles. Already known from New Zealand shallow waters is Kolostoneura novae-zealandiae Dendy and Hindle, 1907 with 10 tentacles. Our new species clearly falls into the genus Paradota .

Three species have been previously described for this genus. Our new species differs from them all ( Table 1 ). Firstly the type species P. ingolfi from European and American North Atlantic Coast has tentacle rods which are similar in appearance to P. plentyensis with straight smooth lengths and branching at the extremities. However the tentacles rods are much longer (200 µ m compared to 100 µ m) in P. ingolfi .

Secondly, P. weddellensis Gutt, 1990 has been described from Antarctic waters. This species differs from P. plentyensis as it does not have miliary granules in the longitudinal muscles and the tentacle ossicles are more curved. P. weddellensis is a pale red to pale purple colouration compared to the deep even purple colour (live and preserved) found in P. plentyensis . Paradota marionensis Massin, 1992 was described from Marion Island in the Southern Indian Ocean. This species has similar tentacle arrangement and polian vesicles to P. plentyensis but is an opaque pale purple. The calcareous ring is almost identical to our new species. The tentacle ossicles are distinctly more curved in P. marionensis forming an almost complete ‘C’.

With a combination of the features described above we have a new species and a first encounter of the Paradota genus in New Zealand waters.