Neophasis oculata (Chubrik, 1966)
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publication ID |
https://doi.org/ 10.1016/j.ijppaw.2021.05.001 |
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persistent identifier |
https://treatment.plazi.org/id/CB7C1671-0068-FFFA-733B-E4E979A0FEE0 |
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treatment provided by |
Felipe |
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scientific name |
Neophasis oculata |
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3.3.1. Intramolluscan stages of Neophasis oculata View in CoL ( Fig. 2 View Fig )
Locality: White Sea; Keret Archipelago, Velikaya Salma Strait (Kandalaksha Bay).
Hosts: Buccinum undatum , Neptunea despecta .
Sites: Reproductive and digestive gland.
Prevalence: 0.4% (5 of 1376) B. undatum in Keret Archipelago; 7% (5 of 68) N. despecta in Keret Archipelago; 66% (2 of 3) N. despecta in Velikaya Salma Strait.
Vouchers: Isogenophores (NO006–NO011) corresponding to isolates No 9, 10 and 13 deposited in the collection of the Department of Invertebrate Zoology of Saint Petersburg University .
Description:
Daughter rediae ( Fig. 2A View Fig ).
[Measurements based on 20 specimens fixed with saturated solution of mercury (II) chloride with acetic acid: 10 specimens from B. undatum and 10 specimens from N. despecta .]
Rediae elongated, sausage-shaped, 828–1964 (1345) × 133–251 (181). Posterior end usually pointed. Mouth terminal, pharynx small, oval, 35–51 (44) × 18–48 (35). Cecum oval, short, 33–111 (65) × 24–46 (32). Brood cavity occupying almost all inner space of rediae, containing cercarial embryos at different stages of development. Birth pore with distinct birth canal posterior to pharynx. Germinal mass at posterior body end, embedded in parenchyma.
Cercariae ( Fig. 2B and C View Fig ).
[Measurements based on 20 specimens fixed with saturated solution of mercury (II) chloride with acetic acid.]
Distome larvae with pair of pigmented eyespots and simple tail ( Fig. 2C View Fig ). Body 245–504 (356) long, 90–139 (116) wide, bottle-shaped, with narrowed anterior and dilated posterior ends ( Fig. 2B View Fig ; 3A, F View Fig ).
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Spines small, simple; size and density decreasing towards posterior end ( Fig. 3F View Fig ). Tail simple, 260–826 (524) long, 33–52 (46) wide at base ( Fig. 2C View Fig ; 3A View Fig ). Oral sucker subterminal, oval, 35–58 (46) × 34–48 (40). Ventral sucker spherical, 33–50 (42) × 35–47 (40), near center of body, slightly closer to posterior end ( Fig. 2B View Fig ; 3A, F View Fig ). Sucker-ratio 1:0.67–1.23 (0.93). Prepharynx long ( Fig. 2B View Fig ). Pharynx pyriform to oval ( Figs. 2B View Fig and 3A, B, H, I View Fig ), 21–26 (24) × 11–18 (14). Oesophagus primordium short ( Fig. 2B View Fig ; 3A, H View Fig ). Ceca primordia as rows of cells, extending to posterior body end, lateral to excretory vesicle ( Fig. 2B View Fig ; 3A, H View Fig ). Cerebral ganglion dorsal to prepharynx ( Fig. 2B View Fig ; 3A, B, G View Fig ). Two pigmented eyespots, large, oval, lateral to oesophagus ( Fig. 2B View Fig ; 3 View Fig A-E, H, I). Phospho Y positive structure (unpaired unpigmented eyespot) anteromedial to pigmented eyespots ( Fig. 2B View Fig ; 3I View Fig ); also staining with TRITC-labeled phalloidin ( Fig. 3I View Fig ). Thirteen small unicellular penetration glands in two groups ( Fig. 2B View Fig ; 3A View Fig ). Anterior group of six glands in forebody, lateral to pharynx ( Fig. 2B View Fig ; 3A View Fig ); ducts running medially to pigmented eyespots towards anterior body end ( Fig. 2B View Fig ; 3B View Fig ). Posterior group of seven glands lateral and posterior to ventral sucker ( Fig. 2B View Fig ; 3A View Fig ); only five ducts present, running lateral to anterior penetration glands and pigmented eyespots towards anterior body end ( Figs. 2B View Fig and 3B View Fig ). Each duct opening through individual pore near anterior edge of oral sucker, 11 pores in total ( Fig. 2B View Fig ). Cystogenous glands not detected. Excretory vesicle in hindbody, I-shaped, voluminous, slightly asymmetrical ( Fig. 2B View Fig ; 3A, C View Fig ); sometimes appearing Y-shaped, due to dilated proximal parts of main collecting ducts. Excretory vesicle wall thick, staining slightly with eosin ( Fig. 3C View Fig ). Excretory system of ‘‘Mesostoma” type ( Fig. 2B View Fig ). Main collecting ducts dividing into anterior and posterior parts near anterior edge of ventral sucker. Excretory formula 2[(4 + 4 + 4) + (4 + 4 + 4)] = 48. Caudal excretory duct present in underdeveloped cercariae and absent in infective cercariae ( Fig. 2B View Fig ; 3H View Fig ). Small testes primordia in hindbody, slightly oblique; posterior testis slightly larger than anterior one ( Fig. 2B View Fig ). Vasa efferentia visible ( Fig. 2B View Fig ). Cirrus-sac primordium as C-shaped group of cells ( Fig. 2B View Fig ). Primordium of female reproductive system crooked, compact (including metraterm, uterus, ootype, Laurer’ s canal, oviduct and ovary); from its dorsal part vitellarium primordium passing as two strands of cells laterally, then dividing into short anterior and long posterior part ( Fig. 2B View Fig ).
Developing cercariae and mucoid structures ( Fig. 3A, D, E View Fig ).
Cercariae leave rediae underdeveloped, and morphogenesis is completed in the digestive gland of the host. Development of pigmented eyespots begins soon after formation of the tail bud ( Fig. 2A View Fig ). Mucoid glands as described in Xiphidiata and Opisthorchiata are absent. Mucoid substances were found in cytons at the dorsal side of the body, and in the tail of cercaria embryos ( Fig. 3D and E View Fig ). Development of mucoid cytons begins before the larvae leave the rediae ( Fig. 3E View Fig ). During the final stages of cercarial development outside rediae, the mucoid substance is
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transferred into the tegument which becomes swollen ( Fig. 3A View Fig ).
Remarks:
In early infections daughter rediae are located only in the reproductive gland while at more advanced stages of infection they move into the digestive gland. We observed numerous infective cercariae only in the two specimens of B. undatum captured in April 2018. All the other infected specimens of B. undatum and N. despecta contained mostly underdeveloped larvae, with few infective cercariae among them.
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