Eucestoplana ittanmomen, Tsuyuki & Oya & Kajihara, 2023
|
publication ID |
https://dx.doi.org/10.3897/zse.99.102604 |
|
publication LSID |
lsid:zoobank.org:pub:D7ACA636-4B03-46F4-AF77-D5DEC8EB7084 |
|
persistent identifier |
https://treatment.plazi.org/id/0D14C91F-156B-46C2-88C4-B1E63F94AC34 |
|
taxon LSID |
lsid:zoobank.org:act:0D14C91F-156B-46C2-88C4-B1E63F94AC34 |
|
treatment provided by |
|
|
scientific name |
Eucestoplana ittanmomen |
| status |
sp. nov. |
Eucestoplana ittanmomen sp. nov.
Figs 4 View Figure 4 , 5 View Figure 5
Material examined.
Holotype: Japan •1; Okinawa Prefecture, the Okinawa Islands, Kouri Island, Tokei Beach ; 26°42.86'N, 128°1.108'E; intertidal gravelly sediments; 11 Aug. 2021; A. Tsuyuki and Y. Oya leg.; sagittal sections (6 slides); GenBank: LC740490 View Materials (16S), LC740492 View Materials (18S), and LC740495 View Materials (28S); ICHUM 8443 GoogleMaps . Paratype: Japan •1; same data as for holotype; sagittal sections (4 slides); ICHUM 8444 GoogleMaps .
Type locality.
Japan, Okinawa Prefecture, Kunigami, Nakijin, Kouri Island, Tokei Beach (26°42.86'N, 128°1.108'E).
Diagnosis.
Body slender and elongated; anterior margin rounded; dorsal surface translucent white without any color pattern; pair of eyespot-clusters distributed along midline in front of brain; penis papilla with heavily sclerotized stylet; penis sheath dome-shaped with external epithelium covered with cilia; cilia absent in inner wall of male atrium; adhesive organ present at posterior end of body.
Description of holotype.
Body slender and elongated, 26 mm long and 0.75 mm wide in living state (Fig. 4A View Figure 4 ); anteriorly rounded, spreading like fan; posteriorly tapered. Dorsal surface smooth, translucent, without any color pattern. Ventral surface translucent. Tentacles absent. Pair of eyespot-clusters, each composed of 12-14 eyespots (12 on left; 14 on right), distributed along midline in front of brain (Fig. 4B View Figure 4 ), spreading out in fan shape anteriorly. Intestine highly branched without anastomosing, spreading throughout body, not reaching body margin. Pharynx ruffled, 1.94 mm long, situated on last fourth of body (Fig. 4A, C View Figure 4 ). Mouth opening at last third of pharyngeal pouch (Fig. 4C View Figure 4 ). Male gonopore opening at last ninth of body (Fig. 4A View Figure 4 ). Female gonopore situated posterior to male gonopore. Male copulatory apparatus consisting of true seminal vesicle, interpolated prostatic vesicle, and penis papilla with stylet (Fig. 4A View Figure 4 ). Testicular follicles arranged in single, lateral, longitudinal row on each side, about half length of body, running anteriorly from area in front of pharynx (Fig. 4A View Figure 4 ). Pair of sperm ducts separately entering proximal end of seminal vesicle; each duct forming spermiducal vesicle before entering seminal vesicle (Fig. 5A, B View Figure 5 ). Seminal vesicle extending posteriorly, about 700 µm long and 90 µm wide at its widest point, posteriorly turning 180° right in front of female copulatory apparatus before running anteriorly to lead to ejaculatory duct at position of proximal end of penis stylet; thick muscular wall, about 19 µm thickness, coating seminal vesicle and ejaculatory duct (Fig. 5A, B View Figure 5 ). Prostatic vesicle oval, elongated, with about 18-µm thick muscular wall, lined with thick glandular epithelium; distal end of prostatic vesicle forming penis papilla (Fig. 5A, C View Figure 5 ). Penis papilla with wedged, strongly sclerotized stylet (131 µm long), projecting into male gonopore (Fig. 5A, D View Figure 5 ). Penis sheath dome-shaped, about 184 µm wide at its widest point, housing penis stylet (Fig. 5A, C, D View Figure 5 ); external epithelium being exposed to male atrium, former being lined with cilia (Fig. 5C, D View Figure 5 ); penis pocket lined with non-ciliated epithelium. Male atrium lined with thin epithelium without cilia (Fig. 5C, D View Figure 5 ). Male gonopore about 27 µm deep. Female copulatory organ lacking Lang’s vesicle. Pair of oviducts running posteriorly, then connecting to proximal end of vagina independently. Vagina narrow, curved dorsoventrally, lined with ciliated epithelium, leading to female gonopore via narrow cement pouch (Fig. 5A, E View Figure 5 ). Numerous cement glands releasing their contents into cement pouch (Fig. 5E View Figure 5 ). Adhesive organ located at posterior end of body.
Description of paratype.
Due to lack of anterior part of body, body length, width and eyespot arrangements unknown. Body coloration same as holotype. Pharynx ruffled, 1.27 mm in length; mouth opening at posterior region of pharyngeal pouch. Male copulatory apparatus composed of elongate seminal vesicle, interpolated prostatic vesicle, and penis papilla with wedged stylet (106 µm long); penis stylet slenderer than that of holotype. Penis sheath dome-shaped, with external epithelium ciliated; numerous eosinophilic glands piercing distal part of penis sheath. Male atrium covered with non-ciliated epithelium. Female copulatory apparatus same as holotype except for shape of cement pouch being more expanded than that of holotype. Adhesive organs present at posterior end of body (Fig. 5F View Figure 5 ).
Etymology.
The specific name ittanmomen (Ittan-momen) is a Japanese noun, representing the name of one of the “yokai” (a class of supernatural entities and spirits in Japanese folklore). It is named after the long and narrow cloth-like white body of the flatworm, which evokes the similar-looking yokai, Ittan-momen.
Distribution.
To date, only from the Okinawa Islands, Japan.
Remarks.
Our specimens belong to Eucestoplana based on the following characteristics: i) the evident sclerotized penis stylet and ii) a female copulatory apparatus without any accessory ducts or Lang’s vesicle. Eucestoplana ittanmomen sp. nov. can be easily distinguished from E. meridionalis by the following characteristics: i) translucent body, ii) fewer eyespots distributed only anterior to the brain, and iii) the presence of the adhesive organ (Table 3 View Table 3 ). Our new species is most similar to E. cuneata in having the following characteristics: i) around 30 eyespots distributed only anterior to the brain, ii) a wedge-shaped stylet, and iii) the adhesive organ located on the posterior end of the body. However, E. ittanmomen sp. nov. is differentiated from E. cuneata by the following characteristics: i) the shape of the penis sheath (dome-shaped in E. ittanmomen sp. nov.; cone-shaped in E. cuneata ), ii) the arrangement of the cilia in the inner wall of the male atrium (only present along the outside of the penis sheath in E. ittanmomen sp. nov.; surrounding the whole male atrium in E. cuneata ), and iii) the stylet length (106-131 µm in E. ittanmomen sp. nov.; 70 µm in E. cuneata ). Eucestoplana ittanmomen sp. nov. can be also distinguished from E. cf. cuneata collected from the same locality by the same morphological differences as mentioned above. In addition, the genetic distance for 16S and 28S sequences between them could support that the two entities are likely to be genetically independent. The values for 16S (3.153%-3.378%) were much larger than the three interspecific values 0.5-1.8%, which were observed among three species of Notocomplana ( N. hagiyai , N. japonica , and N. koreana ) ( Oya and Kajihara 2017). The p -distance between the 28S sequences of E. ittanmomen sp. nov. and E. cf. cuneata was also much larger than that between C. salar and C. techa , which are clearly different species because of their morphological difference (Table 2 View Table 2 ).
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.
|
Kingdom |
|
|
Phylum |
|
|
Order |
|
|
Family |
|
|
Genus |