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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 3068

Sudzuki Minoru; [On the General Structure and the Seasonal Occurrence of the Males of Some Japanese Rotifers V.]. Zoological Magazine (Dobutsugaku Zasshi) 65(9):329-334, 1956

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The present paper deals with the general structure and the seasonal occurrence of the males in two species of rotifers, Ascomorpha agilis and A. ovalis, under the family Gastropodidae (cf. Anapodidae). 15) Ascomorpha agilis Zacharias: This species appeared early in the beginning of May, but its population was observed in M1 usually from June to the middle of October and the maximum lay almost always in the rainy periods. In R1, however, the species was sporadic throughout the year; in 1953 and 1955 individuals occurred during the short period from late summer to early fall, while in 1952 and 1954 not a single specimen was found. The male was found at the time just before the disappearance of amictic females, namely from the end of September to the beginning of October. A summer stenothermal form. Monocyclic. Total length 57-68 µm, width 34-38 µm. Lorica remarkably well developed, 49~52x30~31 µm in size. The male much resembles the female of Anuraeopsis in its general features. 16) A. ovalis Bergendal (syn. Chromogaster [Anapus] ovalis Bergendal = Ch. testudo Lauterborn); Seasonal occurrence of this species was similar to that of the species mentioned above: the maxima were observed in July and from September to October in M1. In R1, however, this species was sporadic during these five years. As in A. agilis, the males were collected from M1 in the rainy periods, i.e. in the beginning of July in '54 and the middle of October in '55. Presumably dycyclic. 70 µm long, 31 µm broad. Dorsal lorica 46~46.5x24~27 µm, ventral 47.5x30 µm in size. At a glance the male of this species is closely allied to that of A. agilis. The writer is of the opinion that the characters of the male (degenerated) can be used for generic, while those of the female for species diagnosis, and for family diagnosis both can be used. From this viewpoint the Bergendal's species. Anapus ovalis, the male of which is much like, A. agilis, may be comprised within the genus Ascomorpha. Further, the males of these two species under the genus Ascomorpha remind us of the male of the species under the Fam. Trichocerideae rather than those of the genus Gastropus under the Fam. Gastropodidae. Accordingly, it is not appropriate to include the genus Ascomorpha in the Gastropodidae represented by the genus Gastropus, as was done by Harring-Myers and Remane. Furthermore, the young of A. ovalis may perhaps be identical with A. testudo, which has hitherto been treated as a valid species of Chromogaster on the basis of usual taxonomic characters.