Ref ID : 3073
Sudzuki Minoru; [Studies on the Egg-Carrying Types in Rotifera II. Genera Brachionus & Keratella]. Zoological Magazine (Dobutsugaku Zasshi) 66(1):11-20, 1957
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In this paper are dealt with two egg-carrying types found in rotifers of the genera Brachionus and Keratella from Urawa. In the following 11 valid species (with varieties and formae), B. angularis (Female-Female, Male-Female, D-Female), B. benni (Female-Female), B. budapestinensis (Female-Female, Male-Female, D-Female), B. calyciflorus (Female-Female, Male-Female, D-Female), B. diversicornis (Female-Female, Male-Female, D-Female), B. falcatus (Female-Female, Male-Female, D-Female), B. forficula (Female-Female, Male-Female, D-Female), B. leidigi, B. plicatilis (Female-Female, Male-Female), B. quadridentatus (Female-Female), B. urceoralis and B. spp., eggs are carried by a thread-like structure like Gosse's thread of Pompholyx already described. Our thread is clearly distinguishable from Gosse's in thickness, length, transparency and elasticity. All these species have, besides the so-called foot glands, the special glands for secreting this thread at just above the coxal part of their foot, where the large diverticula of the foot glands are also present. Strictly speaking these special glands cannot be referred to as the so-called foot glands, but rather to the style glands mentioned in Pompholyx, and the thread of this type appears to be characteristic to the genus. The author, therefore, would call it the Hudson's thread. All the Keratella species have no foot at the adult stage. The females of three representative species, K. cochlearis (Female-Female, Male-Female, D-Female), K. quadrata (Female-Female, Male-Female, D-Female), K. valga (Female-Female, Male-Female, D-Female) and their varieties and formae are provided also with two kinds of paired glands: the one pair which is situated around the cloaca seems to be the foot glands, while the other pair near the rectum may be regarded as the style glands. Each egg of Keratella is carried by means of two slender, short threads or pedunclets produced by the style glands. If Keratella carries two or more eggs, eggs except the last produced are connected each other by two threads with the eggs subsequently produced, thus forming a series (In genera, Brachionus, Pompholyx and Filinia, on the contrary, each egg is connected separately by a thread with their mother). These threads or pedunclets are not so elastic as Hudson's thread. By the ventral retractors associated with the style glands these threads may be retracted through the cloacal opening into the body. This egg-carrying type is also clearly different from that of the genus Anuraeopsis, which is so closely related to the genus Keratella that formerly it was treated as Anuraea together with three species mentioned in this paper. Since these threads have never been observed, the author would propose to name them Kato's threads. The formation process of the Hudson's and Kato's threads is similar to that of Gosse's thread of Pompholyx described in a previous paper.