Kurzfassung
Almatium gusevi (Chernyshev 1940) (Branchiopoda, Kazacharthra) wird auf der Grundlage eines umfangreichen und sehr gut erhaltenen Materials aus der spättriassischen Huangshanjie-Formation des Turpan-Beckens, Xinjiang Uygur Autonome Region, China, neu beschrieben. Die »Eigenshape«-Analyse der Kopfschildformen bestätigt das Vorhandensein zweier distinkter Formen, die früher als Männchen (kleiner) und Weibchen (größer) gedeutet wurden. Neue Interpretationen führen indessen zu weiteren Spekulationen über die Reproduktion beiAlmatium gusevi, die, außer dem normalen Schlüpfen der Eier aus den Eierstöcken reproduktionsreifer Weibchen, möglicherweise auch folgendermaßen vor sich gehen kann: 1. Bildung ephippiumartiger Ruhestadien, um ein Austrocknen der Umgebung überleben zu können; 2. Entwicklung hermaphroditischer Weibchen; und 3. das Vorkommen zweier größendifferenzierter Klone in einer Population parthenogenetischer Weibchen.
Abstract
Almatium gusevi (Chernyshev 1940), a kazacharthran branchiopod, is redescribed on the basis of plentiful new and well preserved material from the Late Triassic Huangshanjie Formation in the Turpan Basin, Xinjiang Uygur Autonomous Region, China. Eigen-shape analysis of head shield-shapes confirms the occurrence in these fossils of two distinct shapes which were previously interpreted as representing males (smaller) and females (larger). New interpretations, however, lead to further speculation of the reproductive modes inA. gusevi as possibly including, in addition to hatching of normally fertilised eggs from the ovisacs of mature females: 1) formation of ephippium-like resting stages to survive ambiental drying-out; 2) development of hermaphroditic females; and 3) the possible occurrence of two electrophoretically-distinct size-differentiated clones in a population of parthenogenetic females.
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McKenzie, K.G., Pei-Ji, C. & Majoran, S. Almatium gusevi (Chernyshev 1940): Redescription, shield-shapes; and speculations on the reproductive mode (Branchiopoda, Kazacharthra). Paläont. Z. 65, 305–317 (1991). https://doi.org/10.1007/BF02989846
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DOI: https://doi.org/10.1007/BF02989846