Section 39
Chapter 38,094

Composition, origin and formation of the stygobite Cyclopidae fauna of Bulgaria and definition of the kieferi species group of the genus Acanthocyclops Crustacea, Copepoda, Cyclopoida Composition, origine et formation de la faune cyclopidienne stygobie de Bulgarie et definition du groupe despeces kieferi du genere Acanthocyclops Crustacea, Copepoda, Cyclopoida

Pandourski, I.

Museo Regionale di Scienze Naturali Bollettino (Turin) 152: 279-297


ISSN/ISBN: 0392-758X
Accession: 038093190

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A review of the literature data, distribution and habitats of 21 species and subspecies of stygobiont cyclopids discovered in groundwaters of Bulgaria is presented. The male of Acanthocyclops radevi Pandourski is described. Short descriptions and drawings are given to show the variability of important morphological traits (shape of caudal ramus, of swimming legs 1-5 and other characters) of the Bulgarian endemits Acanthocyclops iskrecensis, A. radevi and A. strimonis. The taxonomic status of four species is discussed. The Acanthocyclops kieferi-group of species is redescribed. The species of this group differs from all the other species of the same genus by the following characters: - antennule of 11 articles; - swimming legs 1-4 with 3-segmented exopods; - setal formula of legs 1-4 exopod distal segments spine formula; - inner surface of caudal ramus smooth. The morphological similarity with the group including Acanthocyclops rupestris, A. talievi, A. profundus and A. notabilis from the Baikal lake is discussed. The "kieferi" group includes paleoendemic species remainders of an ancient Boreal fauna, which areal covers part of Western and Eastern Europe and reaches the desert Kizil-Kum in Kazakhstan to the East. All the species of this group are found in groundwaters. The analysis of the paleoecological scenario of the territory of Kazakhstan shows that Acanthocyclops biarticulatus Monchenko (or its ancestor) colonized the subterranean milieu probably during the Oligocene. During the Miocene only its hypogean populations survived because of the destruction of surface habitats during dry climatic periods. The epigean populations of the species of A. kieferi-group disappeared in Europe probably in the late Pliocene and early Quaternary, at the beginning of glacial periods, when the subterranean milieu played a conservative role for the populations of this group.

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