Ref ID : 3074
Sudzuki Minoru; [Studies on the Egg-Carrying Types in Rotifera III. Genus Anuraeopsis]. Zoological Magazine (Dobutsugaku Zasshi) 66(11):407-415, 1957
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The present paper deals with a new type of the egg-carrying in a rotifer found in Urawa (M1 & R1), a type characteristic of the genus Anuraeopsis. In this animal, the egg remains attached to the caudal extremity of the mother worm by means of a prominent protuberance (5-7 by 5-7 µm) formed by a part of the egg-membrane, hitherto known as Gosse's nipple, and not by means of such threads as Hudson's, Gosse's, or Kato's. Now, it has not been explained clearly by what mechanism the mother carries the Gosse's nipple. At the anal region of the worm, there is a special structure which was first discovered by Hudson-Gosse ('86) and thought to be the rectum. Aferwards Weber ('98) called this structure `Un organe membraneux` for convenience the present author here calls this structure Weber's organ) and regarded it as the foot. Later de Beauchamp ('09) took it for the bladder, and recently Donner ('43) for "verbildeter Fuss". The features of Weber's organ described by previous authors are not in accord with one another, although the material used were all identified as A. fissa (Gosse). The present author has been able to study fairly well the said organ extruded from the anal orifice after treating the mother worm with hot water or artificial sea-water. The organ is chiefly characterized by having 1) a stiffened, recurved margin with about 5 membranous fingers (the latter organ is here called - Donner's hooks), 2) an accessory tuft of cilia like sepraanal Sinnesorgan and 3) a mass of glandular cells. Judging from these and other characteristics, the structure under question cannot be the rectrum or the bladder. Moreover, Weber's organ is too specialized to be regarded as a foot, for the foot of common rotifers is provided with toes but not Donner's hooks. In our animal, the laid egg may be held to the mother by the swelling of the sticky Weber's organ. In the case of carrying two eggs, these are connected in a series just like in Keratella, but unlike in Pompholyx, Brachionus and Filinia. The egg-carrying by the aid of Weber's organ with Donner's hooks and Gosse's nipple is assumed to be one of the main generic characters of anuraeopsid rotifers. Now we can safely separate Anuraeopsis fissa from the central group of Anuraea (Syn. Keratella), for in rotifers the type of the egg-carrying, according to the present author's opinion, is specific to each genus, at least under the subfamily Brachioninae.