Polyphemidae of the Pontocaspian Basin

Mordukhai-Boltovskoi, Ph. D.

doi:10.1007/bf00189864

Cited by 20 publications

(8 citation statements)

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“…Finally, cercopagidids are unique in their possession of a tremendously elongate caudal process (formed by retention of shed cuticle), virtual loss of thoracopodal exopods (although still identifiable as such at least in Bythotrephes), possession of a first thoracopod that differs dramatically in shape and size from the other thoracopods, and in the loss of the paired caudal setae in Zoologicu Scripta 24 adults (character set 11). Of the two cercopagidid genera, there is little doubt that Cercopagis is the more derived, given the often bizarre size and form of its caudal process, 'more delicate constitution' (Mordukhai-Boltovskoi 1965: 213), somewhat smaller eye (compared to Bythotrephes), larger thoracopod 1 relative to body size (Mordukhai-Boltovskoi and Rivier, 1987), and reduced size of the caudal articles and their paired spines (Mordukhai-Boltovskoi, 1965, 1968.…”

Section: Onychopod Phylogenymentioning

confidence: 99%

The external morphology of the onychopod ‘cladoceran’ genus Bythotrephes (Crustacea, Branchiopoda, Onychopoda, Cercopagididae), with notes on the morphology and phylogeny of the order Onychopoda

Martin

Cash-Clark

1995

Zoologica Scripta

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The onychopod ‘cladoceran’ genus Bythotrephes Leydig is reviewed and redescribed based on introduced material of the B. cederstroemi‘form’ from the Great Lakes of North America. Reviewed briefly are the systematic history, introduction into North America, and natural history of the genus. Using S.E.M. and light microscopy, we then illustrate a mixture of plesiomorphic and (predominantly) derived features, most of which can be explained as modifications for predation. An emended generic diagnosis includes unique and previously poorly known characters that serve to distinguish Bythotrephes from the confamilial genus Cercopagis, such as a distinctly bilobed labrum, spinose anterior mandibular process, small (exopodal?) spines on the external face of thoracopods 1–3, and a gnathobasic process (proximal endite) on thoracopod 1. A redescription, combined with observations on the external morphology, highlights several morphological peculiarities. These include the strongly bilobed labrum, the loss of one of the original two pairs of maxillae (with a question raised as to which pair has been lost), an unusual point of origin for the ‘proximal endite’ (termed herein the ‘gnathobasic process’ because of uncertainty of homology) on thoracopods two and three, a bulbous process of unknown significance located just posterior to the last thoracopod, and the presence of what might be a remnant of the food groove believed to have been present in a hypothesized ancestral group leading to the Onychopoda. The problem of whether Bythotrephes contains one dimorphic species or two species, B. Iongimanus and B. cederstroemi, is reviewed briefly, and the morphological feature in which these forms differ (the caudal process) is described in detail for the cederstroemi form. Comparison with descriptions of other cercopagidids suggests that Bythotrephes is a highly derived taxon, with short‐abdomen genera of the Podonidae and Polyphemidae (e.g., Polyphemus) appearing closer to the onychopod phyletic stem, and with the more closely related genus Cercopagis more derived still. Phylogeny within the Cladocera, and the possible origin of the Cladocera from a cyclestheria‐like ancestor among the spinicaudate conchostracans, is reconsidered. A hypothesis of evolutionary relationships is presented that depicts the ctenopods and anomopods as having arisen from a hypothetical Cyclestheria‐like ancestor, with the predatory cladoceran taxa Haplopoda and Onychopoda being derived from the base of the anomopod lineage. Some of the many problems in the suggested phylogeny are discussed.

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Section: Onychopod Phylogenymentioning

confidence: 99%

The external morphology of the onychopod ‘cladoceran’ genus Bythotrephes (Crustacea, Branchiopoda, Onychopoda, Cercopagididae), with notes on the morphology and phylogeny of the order Onychopoda

Martin

Cash-Clark

1995

Zoologica Scripta

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“…The fact that most (72%) onychopod species are endemic to the Caspian, Azov and Aral Seas, or to the estuaries and lagoons of the Black Sea ( Fig. 1) suggests that the Ponto-Caspian basin fostered much of the radiation within this group (Zenkevitch, 1963;Mordukhai-Boltovskoi, 1965;Dumont, 1998b). The onychopods are not the only group which diversified in this area.…”

Section: Introductionmentioning

confidence: 99%

“…However, the timing of these radiations and the extent of their diversification outside the Ponto-Caspian area remain uncertain. Unlike other ancient lakes, where adaptive radiations were restricted to benthic lineages, the Ponto-Caspian area fostered several episodes of radiation in planktonic lineages such as Mysis (Vä inö lä , 1995), the cyclopoid copepods (Monchenko, 1998) and the onychopods (Mordukhai-Boltovskoi, 1965). Most of these groups are euryhaline, which suggests that fluctuations in salinities, coupled with the fragmentation of waterbodies within the Ponto-Caspian basin, were important in triggering their diversification (Zenkevitch, 1963;Dumont, 1998b).…”

Section: Introductionmentioning

confidence: 99%

Phylogeny and adaptive radiation in the Onychopoda (Crustacea, Cladocera): evidence from multiple gene sequences

Cristescu

Hebert

2002

Journal of Evolutionary Biology

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Members of the order Cladocera show remarkable morphological and ecological diversity. One of the most spectacular adaptive radiations in this group has involved species of the suborder Onychopoda, which have adopted a novel feeding strategy, predation, and have colonized habitats with a broad range of salinities. In order to evaluate the origins and systematics of this group, we derived a molecular phylogeny for its three component families including nine of 10 recognized genera based on three mitochondrial (mt) gene sequences: cytochrome c oxidase subunit I (COI), the ribosomal small and large subunits (12S and 16S) and one nuclear gene sequence: the small ribosomal subunit (18S). Maximum-parsimony, maximum-likelihood and neighbour-joining phylogenetic analyses were largely congruent, supporting the monophyly of the suborder and each of its families. Comparative analyses of data based on total evidence and the conditional combination of the ribosomal genes produced relatively congruent patterns of phylogenetic affinity. By contrast, analyses of single gene results were inconsistent in recovering the monophyletic groups identified by the multigene analyses. Based on the reconstructed phylogeny, we discriminate among the existing hypotheses regarding the evolutionary history of the onychopods. We identify a prolonged episode of speciation from the Miocene to the Pleistocene with two pulses of diversification. We discuss our results with reference to the geological history of the Ponto-Caspian basin, the region which fostered the onychopod radiation.

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“…The only species with substantially lower lipid storage on the mass-specific basis was the invasive onychopod cladoceran Cercopagis pengoi (Fig. 2), also of freshwater origin (Mordukhai-Boltovskoi, 1965). Since its appearance in the Baltic Sea in the mid-1990-ties, Cercopagis has become a common prey for zooplanktivorous fish (Gorokhova et al , 2004).…”

Section: Discussionmentioning

confidence: 99%

Individual body size as a predictor of lipid storage in Baltic Sea zooplankton

Gorokhova

2019

Journal of Plankton Research

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The size structure of a zooplankton community is frequently used as a trait reflecting functional properties, including biochemical composition. Therefore, a shift in zooplankton body size can reflect shifts in the nutritional quality of zooplankton. In dominant Baltic copepods and cladocerans, neutral to polar lipid ratio (NL/PL ratio), a proxy for the mass-normalized lipid storage, was determined and related to individual body weight. A significant relationship between the NL/PL ratio and body weight was found; the latter was the strongest and the most significant predictor of the lipid storage capacity across different species and developmental stages. These findings provide support for using mean body weight in zooplankton community as a proxy for lipid storage capacity of zooplankton prey and justify applicability of zooplankton mean size as an indicator of nutritional conditions for Baltic zooplanktivores.

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Polyphemidae of the Pontocaspian Basin

Cited by 20 publications

References 0 publications

The external morphology of the onychopod ‘cladoceran’ genus Bythotrephes (Crustacea, Branchiopoda, Onychopoda, Cercopagididae), with notes on the morphology and phylogeny of the order Onychopoda

The external morphology of the onychopod ‘cladoceran’ genus Bythotrephes (Crustacea, Branchiopoda, Onychopoda, Cercopagididae), with notes on the morphology and phylogeny of the order Onychopoda

Phylogeny and adaptive radiation in the Onychopoda (Crustacea, Cladocera): evidence from multiple gene sequences

Individual body size as a predictor of lipid storage in Baltic Sea zooplankton

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