The family Ascothoracidae Grygier, 1987, a review with descriptions of new abyssal taxa parasitizing ophiuroids and remarks on the invalidity of the genus Parascothorax Wagin, 1964 (Crustacea: Thecostraca: Ascothoracida)

Kolbasov, G.A.; Petrunina, A.S.

Авторы: Kolbasov G.A., Petrunina A.S.
Журнал: Marine Biodiversity
Год издания: 2018
Издательство: Springer Verlag
Местоположение издательства: Germany
Первая страница: 1
Последняя страница: 31
DOI: 10.1007/s12526-018-0921-6
Аннотация: Two new ascothoracidan species in the family Ascothoracidae Grygier, 1987, Ascothorax rybakovi sp. nov. and Cardiosaccus pedri gen. et sp. nov., are described from the Kuril-Kamchatka Trench at abyssal depths of 5150–5700 m. They are among the deepest known ascothoracidans. They live as mesoparasites in permanent cysts within the bursae of the brittle stars Ophiacantha pacifica Lütken and Mortensen, 1899 and Amphiophiura pacifica Litvinova, 1971, respectively. This is the first study of new forms of Ascothoracidae in which SEM has been used in the descriptions, including the lattice organs and the early nauplius. Cardiosaccus differs from Ascothorax in displaying the following apomorphic traits: (i) absence of thoracopod 1; (ii) a smaller fifth antennular segment that is completely fused with the claw; (iii) absence of small setae at the base of this claw; and (iv) an extremely large ventral protrusion of the fourth abdominal segment. Material of Parascothorax synagogoidesWagin, 1964 from near the type locality, studied with SEM, could not be distinguished from Ascothorax by any reliable morphological criteria. Cyst structure and the manner of cyst formation cannot be used, because although cyst is the result of the parasites activity, this is a feature of the host, not something inherent to the parasite. Moreover, the inferred settlement of the larvae of P. synagogoides on the outer edge of the bursal slit is best regarded as plesiomorphic behavior, reflecting how the Ascothoracidae became bursal mesoparasites in the first place. We therefore regard Parascothorax as invalid and refer P. synagogoides to Ascothorax. Within the family Ascothoracidae as now constituted, Ascothorax is cosmopolitan and speciose and includes species that exclusively infect a single host species, whereas Cardiosaccus is monotypic and restricted to the northwest Pacific. Ascothorax rybakovi sp. nov. is the third species of this genus known to harbor hyperparasitic cryptoniscid isopods.
Добавил в систему: Колбасов Григорий Александрович

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The family Ascothoracidae Grygier, 1987, a review with descriptions of new abyssal taxa parasitizing ophiuroids and remarks on the invalidity of the genus Parascothorax Wagin, 1964 (Crustacea: Thecostraca: Ascothoracida)статья

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