Pseudicyema daioense, Furuya & Moritaki, 2022
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publication ID |
https://doi.org/ 10.12782/specdiv.27.181 |
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publication LSID |
lsid:zoobank.org:pub:03A070DC-A02C-4FF8-A00D-FD59C7614189 |
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persistent identifier |
https://treatment.plazi.org/id/06F5F6E3-0ED4-4F07-ABC9-141F824AEED6 |
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taxon LSID |
lsid:zoobank.org:act:06F5F6E3-0ED4-4F07-ABC9-141F824AEED6 |
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treatment provided by |
Felipe |
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scientific name |
Pseudicyema daioense |
| status |
sp. nov. |
Pseudicyema daioense sp. nov.
[New Japanese name: Daiō-nihaichū] ( Figs 24 View Fig , 25 View Fig ; Tables 1–3)
Diagnosis. Small- to medium- sized dicyemid, body length reaching 1550µm. Calotte cap-shaped. Vermiform stages with 29–35 peripheral cells: 4 propolar cells+4 metapolar cells+2 parapolar cells+19–25 trunk cells. Infusoriform embryos with 39 cells; refringent bodies solid; and 2 nuclei present in each urn cell.
Description. Nematogens ( Figs 24a–c, d View Fig , 25a, c View Fig ). Body length 850–1550 µm, width 50–81µm; widest in region of parapolars; trunk width mostly uniform. Peripheral cell number 29–35 ( Table 2): 4 propolar cells+4 metapolar cells+2 parapolar cells+17–23 diapolar cells+2 uropolar cells. Calotte cap-shaped, rounded anteriorly; cilia about 4 µm long, oriented anteriorly. Propolar cells equal to or larger than metapolar cells, their nuclei equal to or smaller than metapolar cell nuclei. Propolar cells occupy anterior 50–60% of calotte length when viewed laterally ( Figs 24a, b View Fig , 25a, b View Fig ). Cytoplasm of propolar cells more darkly stained by hematoxylin than that of other peripheral cells ( Fig. 24a, b View Fig ). Axial cell cylindrical, rounded anteriorly, extending forward to base of metapolar cells ( Figs 24a, b View Fig , 25a, b View Fig ). About 10 vermiform embryos present per axial cell of large individuals. Accessory nuclei seen in trunk peripheral cells.
Vermiform embryos ( Figs 24c View Fig , 25f, g View Fig ). Full-grown vermiform embryos length 52–88µm, 15–21 µm in width. Peripheral cell number 29–35 ( Table 2); trunk cells arranged in opposed pairs. Anterior end of calotte rounded. Axial cell rounded anteriorly, extending to the base of propolar cells ( Figs 24c View Fig , 25g View Fig ). Axial cell of full-grown embryos with 2 agametes.
Rhombogens ( Figs 24d, e View Fig , 25c, e View Fig ). Body length 750– 1580 µm, similar to that of nematogens, in length and 42–75 µm in width. Peripheral cell number typically 29–35 ( Table 2). Calotte, axial cell shape and anterior extent similar to nematogens. Maximum of 2 infusorigens present in the axial cell of each parent individual. About 60 infusoriform embryos present per axial cell of large individuals.
Infusorigens ( Figs 24e View Fig , 25h; n View Fig =10). Mature infusorigens medium-sized; composed of 7–12 (mode 8) external cells (oogonia and primary oocytes)+3–5 (mode 4) internal cells (spermatogonia, primary spermatocytes, and secondary spermatocytes)+4–13 (mode 4) spermatozoa. Mean diameter of fertilized eggs 11.0 µm; that of spermatozoa 3.1 µm. Axial cell round or ovoid, diameter 12–15 µm.
Infusoriform embryos ( Figs 24f, g View Fig , 25i–k; n View Fig =27). Fullgrown embryos large, length 22.6±2.2 µm (mean±SD, excluding cilia); length–width–height ratio 1.0:0.86: 0.86; shape ovoid, pointed posteriorly; cilia at posterior end 7 µm long. Refringent bodies present, solid, occupying anterior 40–50% of embryo length when viewed laterally ( Figs 24f View Fig , 25k View Fig ). Cilia project from ventral internal cells into urn cavity ( Fig. 25k View Fig ). Capsule cells contain small granules ( Fig. 25k View Fig ). Mature embryos with 39 cells: 35 somatic+4 germinal cells. Somatic cells of several types present: external cells covering large part of anterior and lateral surfaces of embryo (2 enveloping cells); external cells with cilia on external surfaces (2 pairs of dorsal cells+1 median dorsal cell+2 dorsal caudal cells+2 lateral caudal cells+1 ventral caudal cell+ 2 lateral cells+2 posteroventral lateral cells); external cells with refringent bodies (2 apical cells); external cells without cilia (1 couvercle cell+2 anterior lateral cells+2 first ventral cells+2 second ventral cells+2 third ventral cells); internal cells with cilia (2 ventral internal cells); and internal cells without cilia (2 dorsal internal cells+2 capsule cells+4 urn cells). Each urn cell containing 2 nuclei and a germinal cell ( Fig. 25k View Fig ). All somatic nuclei pycnotic in mature infusoriform embryos.
Remarks. Pseudicyema daioense sp. nov. is the first species of the genus found in S. lorigera and is very similar to P. cappacephalum , P. anemophilum sp. nov., and P. cupulacephalum sp. nov. in the calotte shape and the number of infusoriform embryos. However, P. daioense sp. nov. is distinguished from P. cappacephalum and P. anemophilum sp. nov. in the anterior extent of adult vermiform stages (metapolar cells vs. propolar cells) ( Furuya 2009), and from P. cupulacephalum sp. nov. by the shape of anterior axial cell of vermiform embryos (rounded vs. pointed) and the external shape of second ventral cells of infusoriform embryos (extended laterally vs. located ventrally).
Etymology. The species name “ daioense ” refers to the type locality, near Cape Daio in the picturesque Ise-Shima National Park at the northern end of Kumano Sea.
Taxonomic summary. Type material: a syntype slide (NSMT-Me-67) collected on 26 February 2016; additional syntypes on slide series No. OL3383 (5 slides) in the author’s collection.
Type locality: off Minami-Ise (34°08′N, 136°34′E), Mie Prefecture, Honshu, the Kumano Sea, Japan, depth 360 m GoogleMaps .
Other materials examined: slide series No. SA3382 (each 5 slide) collected off Minami-Ise (34°08′N, 136°34′E), Mie Prefecture, Honshu, the Kumano Sea, Japan, depth 360 m, 26 February 2016, in the author’s collection GoogleMaps .
Host: symbiotype, Sepia aureomaculata Okutani and Horikawa, 1987 (Mollusca: Cephalopoda: Sepiida ), male (mature), 82 mm ML (NSMT-Mo-85909).
Site : anterior ends (calottes) attach to surfaces of the renal appendages or inserted into crypts of the renal appendages within the renal sacs.
Prevalence: in 4 of 5 host specimens examined (80%).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.