Dicyemennea desmocephalum, Furuya, 2018
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publication ID |
https://doi.org/ 10.12782/specdiv.23.143 |
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publication LSID |
lsid:zoobank.org:pub:82CD9349-810A-42F1-A602-343EBA1AE7A4 |
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persistent identifier |
https://treatment.plazi.org/id/6598A34C-29F7-49BB-80B9-49543EEAF765 |
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taxon LSID |
lsid:zoobank.org:act:6598A34C-29F7-49BB-80B9-49543EEAF765 |
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treatment provided by |
Felipe |
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scientific name |
Dicyemennea desmocephalum |
| status |
sp. nov. |
Dicyemennea desmocephalum sp. nov.
( Figs 18 View Fig , 19 View Fig ; Tables 2, 3)
Diagnosis. Medium dicyemid; body length to 1,300 µm. Calotte disc-shaped. Vermiform stages with 23 peripheral cells: 4 propolars+5 metapolars+2 parapolars+12 trunk cells. Infusoriform embryos with 39 cells; refringent bodies solid; 2 nuclei present in each urn cell.
Description. Nematogens ( Figs 18a, c, d, f View Fig , 19a, c View Fig ). Body length 500–1,320 µm and width 100–350 µm; widest in region of parapolars; trunk width narrower to posterior. Peripheral cell number 23 ( Table 3): 4 propolars+5 metapolars+2 parapolars+10 diapolars+2 uropolars. Calotte discshaped, cilia on calotte about 6 µm long, oriented anteriorly. Propolar cells and their nuclei larger than metapolar cells and their nuclei ( Figs 18f View Fig , 19c View Fig ). Cytoplasm of propolar and metapolar cells more darkly stained by hematoxylin than cytoplasm of other peripheral cells. Individuals gather, adhere one another at periphery of metapolar cells, to form an aggregated mass ( Fig. 18a View Fig ) that covering surface of renal appendages and inner surface of renal sacs. Verruciform cells present. Axial cell cylindrical, enlarged anteriorly; cell extending forward to propolar cells ( Figs 18d View Fig , 19a View Fig ). About 90 vermiform embryos per axial cell of large individuals.
Vermiform embryos ( Figs 18e View Fig , 19d, e View Fig ). Full-grown vermiform embryo length 92–220 µm and width 20–25 µm. Peripheral cell number 23 ( Table 3); trunk cells arranged in opposed pairs. Anterior end of calotte rounded. Axial cell rounded anteriorly, extending to propolar cells. Anterior abortive axial cell absent. Axial cell of full-grown embryos with 2 agametes.
Rhombogens ( Figs 18b, g View Fig , 19b View Fig ). Body similar in length to nematogens, length 500–1,150 µm and width 200–440 µm. Peripheral cell number 23 ( Table 3). Calotte disc-shaped. Axial cell shape and anterior extent similar to those of nematogens. Verruciform cells present. Usually, 4–9 (maximum 10) infusorigens per axial cell, of each parent individual. Usually, 60–100 (maximum 343) infusoriform embryos per axial cell of large individuals. Accessory nuclei occasionally present in trunk cells.
Infusorigens ( Figs 18h View Fig , 19f; n View Fig =20). Mature infusorigens large, composed of 30–105 (mode 58) external cells (oogonia and primary oocytes) +20–64 (mode 33) internal cells (spermatogonia, primary spermatocytes, and secondary spermatocytes)+30–143 (mode 48) spermatozoa. Mean diameter of fertilized eggs 17.3 µm; that of spermatozoa 3.5 µm. Axial cell round, range in diameter from 23–57 µm.
Infusoriform embryos ( Figs 18i, j View Fig , 19g –i; n View Fig =50). Fullgrown embryos large, length 28.3±2.9 µm in length (mean±SD); length-width-height ratio 1.0: 1.0: 0.9; shape round; cilia at posterior end 6 µm long. Refringent bodies present, liquid-form, occupying anterior 10% of embryo length when viewed laterally ( Fig. 19i View Fig ). Cilia project from ventral internal cells into urn cavity ( Fig. 19i View Fig ). Capsule cells contain small granules. 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 paired 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 (2 apical micro cells+1 couvercle cell+2 first ventral cells+2 second ventral cells+2 shield 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 germinal cell ( Fig. 19i View Fig ). All somatic nuclei pycnotic in mature infusoriform embryos.
Remarks. Dicyemennea desmocephalum sp. nov. differs from the other congeners principally on the basis of its distinctly aggregated mass. Dicyemennea leptocephalum sp. nov. forms a similar structure but it is a multinucleated mass. In this respect, D. desmocephalum sp. nov. is clearly distinguished from D. leptocephalum sp. nov.
Etymology. Species name desmocephalum is an adjective composed of 2 Greek roots, desmós and - kephalos meaning “adhered” and “-headed”, in reference to the characteristic adhered heads of the adults.
Taxonomic summary. Type material: a syntype slide (NSMT-Me-55) collected at 13 January 2016; additional syntypes on slide series No. OT3347 (5 slides) in the author’s collection.
Type locality: off Minami-Ise (34°05′N, 136°50′E), Mie Prefecture, Honshu , Kumano-nada Sea, North Pacific Ocean, Japan, depth 360 m GoogleMaps .
Other materials examined: slide series Nos. OT1450–1452 (each 5 slides) collected off Owase (33°54′N, 136°18′E), Mie Prefecture, Honshu , Kumano-nada Sea, North Pacific Ocean, Japan, depth 300 m, 9 June 2004; Nos GoogleMaps . OT3341– 3346 (each 5 slides) collected off Kii-Nagashima (33°58′N, 136°28′E), Mie Prefecture, Honshu , Kumano-nada Sea, North Pacific Ocean, Japan, depth 300 m, 26 February 2016 in the author’s collection GoogleMaps .
Host: symbiotype, Octopus tenuicirrus ( Sasaki, 1929) (Mollusca: Cephalopoda: Octopoda ), male (mature), 67 mm ML (NSMT-Mo-85870).
Site : surface of renal appendages within renal sac.
Prevalence: in 40 of 48 specimens of hosts examined (83.3%).
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.