Sheveleva N.G., Timoshkin O.A., Aleksandrov V.N., Tereza E.P. 2010. A new psammophilic species of the genus Diacyclops (Crustacea: Cyclopoida) from the littoral zone of Lake Baikal (East Siberia) // Invertebrate Zoology. Vol.7. No.1: 47–54 [in English].

Limnological Institute of Siberian Branch of Russian Academy of Sciences, Ulan-Batorskaya, 3, 664033 Irkutsk, Russia; e-mail: shevn@lin.irk.ru

KEY WORDS: Diacyclops zhimulevi Sheveleva et Timoshkin, sp.n., Cyclopoida, Cyclopidae, Lake Baikal, psammon.

ABSTRACT: An illustrated description of Diacyclops zhimulevi Sheveleva et Timoshkin, sp.n. (Crustacea, Cyclopoida: Cyclopidae) is provided. The new species is widely distributed along the southwestern coast of Lake Baikal, inhabiting sandy bottoms of the shallow littoral zone. A comparison is made with the previously studied and closely related species Diacyclops eulitoralis Alekseev et Arov, 1986 from the sandy interstitial environment of Lake Baikal. The new species differs from its most closely related species D. eulitoralis by a combination of characters: shorter, nearly square caudal furca (furcal index 1:1 in contrast to 1:3.5 in D. eulitoralis), a larger number of antennular segments, and a different segment pattern of the swimming legs: 2.2/3.2/3.3/3.3 compared to 2.2/3.2/3.2/3.2 in D. eulitoralis. The armament of the distal endopodal segments of the swimming legs 1 and 2 is generally characterized by presence of a long and stout apical spine. The two species are also clearly divergent in ecology: D. eulitoralis inhabits the upper surf zone of the beach and may fairly be called an interstitial species (Alekseev & Arov, 1986; Boxshall et al., 1993), whereas the new species colonizes sandy bottom of the littoral zone.

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