Browsing by Autor "Jorge S. Coronel"

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A Redescription of Branchinecta pollicifera Harding, 1940, and Its Placement In A New Genus (Branchiopoda: Anostraca: Branchinectidae)
(Oxford University Press, 2011) D. Christopher Rogers; Jorge S. Coronel
Branchinecta pollicifera is redescribed from type material and additional material collected from Bolivian bofedal wetlands. Specific unique gonopod and genital segment features demonstrate that B. pollicifera constitutes a new genus, Archaebranchinecta, morphologically distinct fromBranchinecta sensu stricto. Additionally, in B. pollicifera, the gonopod proximal projection is bifurcated as opposed to a spiniform Branchinecta, and the first abdominal segment bears a pair of ventrolateral spinule covered plates. These plates are unique amongst Anostraca. The form of the male second antennae in this species and in the related fossil species B. barstowensis demonstrates a potential close relationship, and this species is also referred to Archaebranchinecta. We also report melanisation in Andean anostracans.
Differential population history in the migratory catfishes Brachyplatystoma flavicans and Pseudoplatystoma fasciatum(Pimelodidae) from the Bolivian Amazon assessed with nuclear and mitochondrial DNA markers
(Wiley, 2004) Jorge S. Coronel; Gregory E. Maes; S. C. Claus; Paul A. Van Damme; F.A.M. Volckaert
The catfishes Brachyplatystoma flavicans ( n = 49) and Pseudoplatystoma fasciatum ( n = 69) showed comparable low allozyme diversities ( H e = 0·012 and 0·009–0·028, respectively), but contrasting PCR‐RFLP restriction site mitochondrial DNA diversities (three haplotypes: π = 0·034–0·092 and five haplotypes: π = 0·001–0·023, respectively) in the Rio Ichilo and Beni (Bolivia). Genetic homogeneity between samples was high for B. flavicans and lower for P. fasciatum . Based on mitochondrial diversity, both species probably experienced a historic population reduction but at different time scales.
Distribution patterns, population status and conservation of Melanosuchus niger and Caiman yacare (Crocodylia, Alligatoridae) in oxbow lakes of the Ichilo river floodplain, Bolivia
(Vicerractoría Investigación, 2007) Ximena Aguilera; Jorge S. Coronel; Thierry Oberdorff; Paul A. Van Damme
Caiman yacare (lagarto) and Melanosuchus niger (black caiman), sympatric species in the Bolivian Amazon basin, have been severely overexploited in the past. We present the results of a standardized survey of C. yacare and M. niger populations in order to evaluate their actual population status in twelve oxbow lakes of the Ichilo River floodplain. Additionally we explored the effect of environmental and anthropogenic variables on caiman distribution patterns. The average density of C yacare and M niger in the shoreline of floodplain lakes was of 6 and 1 ind/km, respectively. For both species, the population was composed mainly of juvenile individuals. We used regression tree analysis (RTA) to assess patterns of M. niger and C. yacare densities with eight environmental and two anthropogenic variables. The RTA analysis showed that the variation in the densities of both C. yacare (52.4%) and M. niger (36.8 %) was related to water conductivity. For C yacare, higher densities occurred at higher values of water conductivity, while M. niger densities followed an opposite trend, resulting in relatively well spatially segregated populations of the two species. After excluding conductivity, Lake-River Distance (LRD) was shown to be the main splitting variable in the RTA analysis. The observed distribution patterns may be the result of the historical post-hunting situation, in combination with differences in habitat selection by the two species, and competitive exclusion processes between the two species. M. niger, a species reported to be recovering slowly from previous low population levels, appears relatively well protected in the Ichilo river floodplain.
High-altitude peatland temporary pools in Bolivia house a high cladoceran diversity
(Springer Science+Business Media, 2007) Jorge S. Coronel; Steven Declerck; Luc Brendonck
Partial revision of theaduncus‐like species ofPleuroxusBaird, 1843 (Chydoridae, Cladocera) from the southern hemisphere with comments on subgeneric differentiation within the genus
(Taylor & Francis, 2006) Н. Н. Смирнов; Alexey A. Kotov; Jorge S. Coronel
The aim of this study is to revise the aduncus‐like species of the genus Pleuroxus Baird, 1843 (Chydoridae, Cladocera) from the southern hemisphere and test the accuracy of subgeneric differentiation within this genus according to Frey (1993a Frey, D. G. 1993a. Subdivision of the genus Pleuroxus (Anomopoda, Chydoridae) into subgenera worldwide.. Hydrobiologia, 262: 133–144. [Crossref] , [Google Scholar]). Pleuroxus wittsteini Studer, 1878 Studer, T. 1878. Beiträge zur Naturgeschichte wirbelloser Tiere von Kerguelensland.. Archiv für Naturgeschichte, 44: 102–121. [Google Scholar] from the Kerguelen archipelago is re‐examined with special attention to thoracic limbs. Forgotten P. carolinae (Methuen, 1910 Methuen, P. A. 1910. On a collection of freshwater Crustacea from the Transvaal.. Proceedings of the General Meetings for Scientific Business of the Zoological Society of London for, 1910: 148–166. [Crossref] , [Google Scholar]) from the mountains of South Africa is redescribed in detail; it is a species having nine to ten setae in filter plate II, and six to seven setae in filter plate IV, which is a plesiomorphic, non‐oligomerized state. Brief descriptions are also provided for P. scopuliferus (Ekman, 1900 Ekman, S. 1900. Cladoceren aus Patagonien, gesammelt von der schwedischen Expedition nach Patagonien 1899.. Zoologische Jahrbücher, Abteilung für Systematik, Geographie und Biologie der Tiere, 14: 62–84. [Google Scholar]) and P. varidentatus Frey, 1993 Frey, D. G. 1993a. Subdivision of the genus Pleuroxus (Anomopoda, Chydoridae) into subgenera worldwide.. Hydrobiologia, 262: 133–144. [Crossref] , [Google Scholar]. A new species, P. hardingi sp. nov., is reported from high altitudes of the Bolivian Andes; this species was previously misidentified as P. aduncus by Harding (1955 Harding, J. P. 1955. Percy Sladen Trust Expedition. XIX. Crustacea: Cladocera.. Transactions of the Linnean Society of London, 1: 329–354. [Crossref] , [Google Scholar]). A key for identification of aduncus‐like species in the southern hemisphere (except Australia and New Zealand) is proposed. Frey's (1993a Frey, D. G. 1993a. Subdivision of the genus Pleuroxus (Anomopoda, Chydoridae) into subgenera worldwide.. Hydrobiologia, 262: 133–144. [Crossref] , [Google Scholar]) system for differentiation of the subgenera of Pleuroxus is found to be vulnerable in view of the new data. New studies, most probably using genetic methods, are needed for the construction of a consistent phylogenetic tree for the genus.