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O. S. Boikova - One of the best experts on this subject based on the ideXlab platform.
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Postembryonic development in Diaphanosoma Brachyurum (Lievin, 1848) (Crustacea: Ctenopoda: Sididae)
Hydrobiologia, 2005Co-Authors: O. S. BoikovaAbstract:Postembryonic females and males Diaphanosoma Brachyurum from Lake Glubokoe (Moscow) have 3–4 and 3 juvenile instars, respectively. Females and males of the first three postembryonic instars can be identified by the different number of setae and setal rudiments on the proximal and distal segments of the exopodite of the swimming antennae: 3 + 7; ( i + 3) + 7; 4 + ( i + 7), respectively ( i = rudiment of seta). The subsequent instars have 4 + 8 long plumose setae on these segments, but the fourth instar has the proximal lateral seta of the distal exopod segment slightly shorter and thinner than the others. The antennules and copulatory appendages of males are instar-specific. Diaphanosomas show small increments in body length during the postembryonic molts. The largest increments (about 115 μ m) occur during the first or second molts. The allometric equation of Huxley (1924) was used for a comparison of the relative growth rate of different body parts. In the middle of summer, the head and swimming antennae with the body and the antennal exopodite with the antennal basipodite grow in isometry. At the same time, the branches of the swimming antennae and their setae show allometric growth: the exopodite and distal setae grow faster than the endopodite and the lateral setae, respectively.
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The resting eggs of the Ctenopoda (Crustacea: Branchiopoda): a review
Hydrobiologia, 1996Co-Authors: Nikolai M. Korovchinsky, O. S. BoikovaAbstract:The resting eggs of the Ctenopoda have been studied since the second half of the 19th century. By now they are known in 21 species of the group but only in 4 species (Sida crystallina, Diaphanosoma Brachyurum, Penilia avistoris and Holopedium gibberum) have they been investigated thoroughly. Gross and internal structure of eggs are characterized by considerable diversity. In general their structure has much in common with resting eggs of the Anostraca, Notostraca, “Conchostraca” and Onychopoda as well as with that of some other remotely related groups of freshwater invertebrates (Rotifera, Hydra). The taxonomic value of resting eggs is discussed. Probably they play a significant role in determining geographical distribution. Waterfowl are the main agent of their dispersal.
Alfred Seitz - One of the best experts on this subject based on the ideXlab platform.
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Differences in allozyme patterns between Diaphanosoma Brachyurum and Diaphanosoma mongolianum, as revealed in Central European populations
Hydrobiologia, 1995Co-Authors: Jakob Müller, Alfred SeitzAbstract:Recent taxonomic revisions in the genus Diaphanosoma have made the uncertainty in species discrimination with morphological characters obvious. Therefore species characterization on a genetic basis seems to be required. Here we examined the genetic structure of two Diaphanosoma mongolianum populations and three Diaphanosoma Brachyurum populations in Central Europe by allozyme electrophoresis. A genetic differentiation between both species was evident. 5 out of 9 tested loci carried diagnostic alleles. Both species differed in their habitat choice: D. mongolianum was adapted to higher trophic levels than D. Brachyurum . Co-occurrence was observed in a eutrophic lake. Populations sampled from their preferred habitats showed high genotype diversities. Most genotype frequency distributions were in agreement with Hardy-Weinberg expectations and temporal (between years) changes in genotypic compositions were not common. This indicated annually occurring bouts of sexual reproduction, similar to intermittent Daphnia populations. Genetic differentiation among lakes suggested restricted gene flow.
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Differences in allozyme patterns between Diaphanosoma Brachyurum and Diaphanosoma mongolianum, as revealed in Central European populations
Hydrobiologia, 1995Co-Authors: Jakob Müller, Alfred SeitzAbstract:Recent taxonomic revisions in the genus Diaphanosoma have made the uncertainty in species discrimination with morphological characters obvious. Therefore species characterization on a genetic basis seems to be required.
Ulrich Sinsch - One of the best experts on this subject based on the ideXlab platform.
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Tolerance of Ceriodaphnia quadrangula and Diaphanosoma Brachyurum(Crustacea: Cladocera) to experimental soft water acidification
Hydrobiologia, 2005Co-Authors: Heike Kappes, Ulrich SinschAbstract:We analysed in how far the decrease of pH, that is part of the ongoing restoration of the softwater Lake Windsborn (conductivity below 30 μS cm−1), may in future influence the occurrence of the two cladoceran species Ceriodaphnia quadrangula and Diaphanosoma Brachyurum. In the field, the abundance of Ceriodaphnia was positively correlated with lake water pH, whereas there was no correlation between abundance and pH for D. Brachyurum. Experiments on the tolerance against acidification included dynamic (24 h) and static tests (24, 48 h, 30 d), and were conducted with acidified lake water. C. quadrangula tolerated a slight acidification to pH 5.2, but not pH 4.8, whereas the NOEC value seems to be between pH 4.2 and 4.5 for D. Brachyurum. Differences between the experimental NOEC values and field data may be explained by diurnal pH fluctuations and the low ion content of Lake Windsborn which puts an additional physiological challenge to its inhabitants.
Jakob Müller - One of the best experts on this subject based on the ideXlab platform.
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Differences in allozyme patterns between Diaphanosoma Brachyurum and Diaphanosoma mongolianum, as revealed in Central European populations
Hydrobiologia, 1995Co-Authors: Jakob Müller, Alfred SeitzAbstract:Recent taxonomic revisions in the genus Diaphanosoma have made the uncertainty in species discrimination with morphological characters obvious. Therefore species characterization on a genetic basis seems to be required. Here we examined the genetic structure of two Diaphanosoma mongolianum populations and three Diaphanosoma Brachyurum populations in Central Europe by allozyme electrophoresis. A genetic differentiation between both species was evident. 5 out of 9 tested loci carried diagnostic alleles. Both species differed in their habitat choice: D. mongolianum was adapted to higher trophic levels than D. Brachyurum . Co-occurrence was observed in a eutrophic lake. Populations sampled from their preferred habitats showed high genotype diversities. Most genotype frequency distributions were in agreement with Hardy-Weinberg expectations and temporal (between years) changes in genotypic compositions were not common. This indicated annually occurring bouts of sexual reproduction, similar to intermittent Daphnia populations. Genetic differentiation among lakes suggested restricted gene flow.
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Differences in allozyme patterns between Diaphanosoma Brachyurum and Diaphanosoma mongolianum, as revealed in Central European populations
Hydrobiologia, 1995Co-Authors: Jakob Müller, Alfred SeitzAbstract:Recent taxonomic revisions in the genus Diaphanosoma have made the uncertainty in species discrimination with morphological characters obvious. Therefore species characterization on a genetic basis seems to be required.
A. A. Kotov - One of the best experts on this subject based on the ideXlab platform.
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Cladocera (Crustacea, Branchiopoda) of Central Yakutia: 1. Some Representatives of the Families Sididae, Daphniidae, and Ophryoxidae
Biology Bulletin, 2017Co-Authors: A. I. Klimovsky, N. M. Korovchinsky, E. I. Bekker, A. A. KotovAbstract:This series of communications is aimed to report on a study of the water fleas (Crustacea, Cladocera) of Central Yakutia. This first communication provides brief descriptions of the representatives of the families Sididae, Daphniidae, and Ophryoxidae, namely Sida crystallina (O.F. Müller 1776), Diaphanosoma orghidani orghidani Negrea 1982, Diaphanosoma amurensis Korovchinsky et Sheveleva 2009, Diaphanosoma Brachyurum (Liévin 1848), Scapholeberis mucronata (O.F. Müller 1776), Scapholeberis rammneri Dumont et Pensaert 1983, Megafenestra cf. nasuta (Birge 1879), Simocephalus cf. serrulatus (Koch 1841), and Ophryoxus kolymensis Smirnov 1992. Remarks are given on the occurrence of these taxa in Northern Eurasia.
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Cladocera (Crustacea, Branchiopoda) of Central Yakutia: 1. Some Representatives of the Families Sididae, Daphniidae, and Ophryoxidae
Biology Bulletin, 2017Co-Authors: A. I. Klimovsky, N. M. Korovchinsky, E. I. Bekker, A. A. KotovAbstract:This series of communications is aimed to report on a study of the water fleas (Crustacea, Cladocera) of Central Yakutia. This first communication provides brief descriptions of the representatives of the families Sididae, Daphniidae, and Ophryoxidae, namely Sida crystallina (O.F. Muller 1776), Diaphanosoma orghidani orghidani Negrea 1982, Diaphanosoma amurensis Korovchinsky et Sheveleva 2009, Diaphanosoma Brachyurum (Lievin 1848), Scapholeberis mucronata (O.F. Muller 1776), Scapholeberis rammneri Dumont et Pensaert 1983, Megafenestra cf. nasuta (Birge 1879), Simocephalus cf. serrulatus (Koch 1841), and Ophryoxus kolymensis Smirnov 1992. Remarks are given on the occurrence of these taxa in Northern Eurasia.
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Comparative analysis of the late embryogenesis of Sida crystallina (O.F. Müller, 1776) and Diaphanosoma Brachyurum (Lievin, 1848) (Crustacea: Brachiopoda: Ctenopoda)
Hydrobiologia, 1998Co-Authors: A. A. Kotov, Olga S. BoikovaAbstract:The embryonic development of two ctenopods Sida crystallina and Diaphanosoma Brachyurum has been investigated by observing living embryos removed from the female brood pouches. The sequence of morphological changes was analysed, as was the time at which the activity of certain organs began. The timing of these events at 21–22 °C is documented for both species. During embryogenesis four membranes are cast off. The growth in length of embryos began only after the shedding of the external egg envelope. Growth rates throughout embryogenesis are documented. A new outline of ctenopod embryogenesis is proposed. It includes four stages (= instars) demarcated by the shedding of membranes (= moults), as is commonly accepted for juvenile and mature animals in ctenopods and other crustacean groups. These instars are well distinguished morphologically. Their characteristics are presented. Differences in the duration of embryogenesis in Sida and Diaphanosoma are explained by greater extension of the first, and especially the fourth, instars of Sida, while the duration of the second and third instars are approximately the same in both. A list of instar features is given which may be used to determine the instar (and approximate age) of embryos in the broud pouch of ctenopod females from natural populations.