Research Article |
Corresponding author: Tsuyoshi Takano ( ttakano@kiseichu.org ) Academic editor: Edmund Gittenberger
© 2020 Tsuyoshi Takano, Shoichi Kimura, Yasunori Kano.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Takano T, Kimura S, Kano Y (2020) Host identification for the deep-sea snail genus Haliella with description of a new species (Caenogastropoda, Eulimidae). ZooKeys 908: 19-30. https://doi.org/10.3897/zookeys.908.46613
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A new parasitic species of eulimid gastropod, Haliella seisuimaruae sp. nov., is described from bathyal (728–978 m) waters off the Pacific coasts of Japan. It shows the closest resemblance to the type species H. stenostoma from the North Atlantic and Barents Sea in having a tall shell with an almost straight outer lip, but differs in having a junction of the parietal wall and columellar lip at 38% of the aperture height from the suture (33% in H. stenostoma), a slightly wider aperture and a more curved and extended columellar lip. The holotype of H. seisuimaruae sp. nov. was found attached to an irregular sea urchin, Brissopsis cf. luzonica (Spatangoida: Brissidae). This represents the first direct observation of parasitic ecology and echinoderm host for the genus Haliella. A new replacement name, Eulima tsushimensis nom. nov., is proposed here for Eulima stenostoma A. Adams, 1861, which is preoccupied by Eulima stenostoma Jeffreys, 1858 (type of Haliella).
Brissopsis, Echinoidea, Gastropoda, irregular sea urchin, parasite, Vanikoroidea
Snails of the family Eulimidae (Caenogastropoda: Vanikoroidea) are exclusive parasites of echinoderms including all five classes of the phylum, namely Asteroidea (sea stars), Crinoidea (sea lilies and feather stars), Echinoidea (sea urchins), Holothuroidea (sea cucumbers) and Ophiuroidea (brittle stars;
Haliella Monterosato, 1878 is one of such deep-sea genera of Eulimidae without host information. The type species Haliella stenostoma (Jeffreys, 1858) occurs over a wide depth range (50–3000 m) in the North Atlantic and Barents Sea (
Five more species have been described under this genus (
Here, we describe Haliella seisuimaruae sp. nov. from bathyal waters in Japan. The holotype of the species was found attached to an irregular sea urchin, Brissopsis sp. cf. luzonica (Gray, 1851) (Echinoidea: Spatangoida: Brissidae; Figs
Holotype of Haliella seisuimaruae sp. nov. and its host sea urchin Brissopsis sp. cf. luzonica (both
The holotype of Haliella seisuimaruae sp. nov. (Fig.
In regard to the identification of the host, Brissopsis luzonica was described very briefly from Luzon Island, Philippines, without accompanying illustration or depth information (
Two paratypes of the new species (Figs
Specimen | Locality | Coordinates | Depth | Cruise, station number |
---|---|---|---|---|
Holotype | Off Tanabe, Wakayama, Japan | 33°32.2'N, 135°08.1'E | 641–727 m | T/V “Seisui-maru” No. 1803, B2 |
Paratype 1 | Tosa Basin, off Kochi, Japan | 33°00.7'–01.9'N, 133°45.8'–45.4'E | 955–978 m | R/V “Tansei-maru” KT-11-12, K5 |
Paratype 2 | Tosa Basin, off Kochi, Japan | 33°05.5'–04.4'N, 134°03.4'–03.6'E | 728–746 m | R/V “Tansei-maru” KT-11-12, K6-2 |
The snail and sea urchin specimens were sequenced for the mitochondrial cytochrome c oxidase subunit I (COI) gene to confirm their systematic positions and to provide molecular-based identification criteria. Total DNA was extracted from the foot of the three snail specimens, as well as the intestinal tissue of the host Brissopsis, using a DNeasy Blood and Tissue Kit (Qiagen). Partial fragments of the COI gene were amplified with
Phylogenetic trees were reconstructed separately for the snail and host using the maximum likelihood (ML) method. Newly determined fragments of the COI gene were aligned in MEGA7 (
The holotype and paratype 2 of Haliella seisuimaruae sp. nov. yielded near-identical sequences of the COI gene (DDBJ/EMBL/GenBank accession numbers LC514118 and LC514119), with one missense and two silent nucleotide substitutions out of 633 base pairs (bp). No successful amplification was achieved for the paratype 1. Although the caenogastropod affinity of the sequences was verified through BLAST searches, ML tree reconstruction based on this fast-evolving gene resulted in almost no resolution among genera within the superfamily Vanikoroidea or the family Eulimidae (tree not shown). Haliella seisuimaruae sp. nov., the only representative of the genus in the tree, ambiguously clustered with Vanikoro cancellata (Lamarck, 1822) (KT149317) of the polyphyletic Vanikoridae with a bootstrap probability (BP) value of 24%.
The sea urchin parasitized by the holotype of H. seisuimaruae sp. nov. (
Maximum likelihood tree for host sea urchin (Brissopsis sp. cf. luzonica_TT2;
Superfamily Vanikoroidea Gray, 1840
Family Eulimidae Philippi, 1853
Eulima stenostoma Jeffreys, 1858, by monotypy.
Holotype
(
Voucher and shell measurements of type specimens of Haliella seisuimaruae sp. nov.
Specimen | Voucher | Preservation | DNA number | Accession number | Shell height | Shell width | Aperture height | Aperture width | Number of whorls |
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Holotype |
|
Pure ethanol | AORI_YK#3469 | LC514118 | 7.8 mm | 2.0 mm | 2.5 mm | 1.2 mm | 7.8 |
Paratype 1 | MPM Coll. No. 21596 | Dry | AORI_YK#1473 | – | 9.8 mm | 2.2 mm | 2.8 mm | 1.3 mm | 9.0 |
Paratype 2 |
|
Pure ethanol | AORI_YK#1520 | LC514119 | 7.1 mm | 1.8 mm | 2.1 mm | 1.1 mm | 7.5 |
Off Tanabe, Wakayama, Honshu Island, Japan; 33°32.2'N, 135°08.1'E; 641–727 m deep.
The name refers to the T/V “Seisui-maru” of Mie University, which captured the holotype of the new species.
Known only from the localities of the type specimens.
A typical Haliella species with high, narrow aperture. Columellar lip tilted at 20° angle from coiling axis, twisted, extended outward near base; junction of parietal wall and columella at ca. 38% of aperture height from suture.
Shell slender, conical with blunt apex, up to 9.8 mm high, 2.2 mm wide and 9 slightly convex whorls (7.8 mm high, 2.0 mm wide, 7.8 whorls in holotype), smooth, thin but not fragile, translucent white. Protoconch large, smooth, paucispiral with 1.5 whorls, indistinctly demarcated from teleoconch. Teleoconch whorls bear straight, irregularly spaced incremental lines or growth pause scars, which are situated at 0.5, 1.6, 2.2, 2.9, 3.4, 3.7, 4.4, 4.7, 5.3 and 5.8 whorls in holotype. Body whorl occupies 45% of total shell height. Aperture high, narrow and oblique; outer lip simple, only slightly curved or almost straight in lateral view, with its most protruding part at 3/4 of aperture height from suture; parietal callus absent; columellar lip tilted at angle of 20° from coiling axis in holotype, thick, twisted, extended outward near round base; junction of parietal wall and columellar lip placed at ca. 38% of aperture height from suture. Umbilicus absent. Operculum teardrop shaped, thin, yellowish. Pigmented eyes absent.
The generic position of the present species is determined most readily by its shell with (1) a slender and cylindrical outline, (2) a blunt apex, (3) slightly convex whorls, and (4) a high, narrow aperture with (5) a twisted columella (Figs
Haliella seisuimaruae sp. nov. is more easily distinguished from the five other described species of the genus. Haliella ventricosa from the South China Sea is characterized by a larger body whorl relative to the total shell height (> 60%) and an accordingly higher aperture (
As a side note,
This study presents the first direct observation of parasitic ecology and echinoderm host for the genus Haliella. The holotype of H. seisuimaruae sp. nov. was found attached to the dorsal (aboral) side of an irregular sea urchin, Brissopsis sp. cf. cf. luzonica (Fig.
1 | Body whorl occupies ≥ 0.6 times of total shell height | H. ventricosa Feng, 1996 |
– | Body whorl occupies < 0.6 times of total shell height | 2 |
2 | Shell aperture ≥ 2 times as high as wide | 3 |
– | Shell aperture < 2 times as high as wide | 5 |
3 | Columellar lip almost parallel to coiling axis | H. abyssicola Bartsch, 1917 |
– | Columellar lip oblique to coiling axis | 4 |
4 | Junction of parietal wall and columellar lip at 33% of aperture height from suture | H. stenostoma (Jeffreys, 1858) |
– | Junction of parietal wall and columellar lip at 38% of aperture height from suture | H. seisuimaruae sp. nov. |
5 | Parietal wall and columellar lip join in a straight line | H. canarica Bouchet & Warén, 1986 |
– | Junction of parietal wall and columellar lip distinct | 6 |
6 | Shell small, ≤ 3 mm high with up to ca. 5 whorls | H. tyrrhena Di Geronimo & La Perna, 1999 |
– | Shell large, > 5 mm high with more than 7 whorls | H. chilensis Bartsch, 1917 |
We are grateful to the captains and crews of T/V “Seisui-maru” (Mie University) and R/V “Tansei-maru” (
Financial support was provided by JSPS KAKENHI grants (nos. 15J10840, 18H02494 and 19K16221).