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Proposal of research internship abroad associated with the pos-doc project Phylogenetic Study of Priocharax Weitzman & Vari (Teleostei, Characiformes, Characidae) in the Ontogenetic Context: an Approach of the Miniaturization Process

Grant number: 12/01075-1
Support Opportunities:Scholarships abroad - Research Internship - Post-doctor
Effective date (Start): June 01, 2012
Effective date (End): August 31, 2012
Field of knowledge:Biological Sciences - Zoology - Taxonomy of Recent Groups
Principal Investigator:Mônica de Toledo-Piza Ragazzo
Grantee:George Mendes Taliaferro Mattox
Supervisor: Ralf Britz
Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Research place: Natural History Museum, London, England  


Priocharax is a genus of Amazonian miniature fishes that includes two of the smallest characids known. Recently, it was proposed as closely related to Heterocharax, Hoplocharax and Lonchogenys, all with diminute representatives, but the relationships among these genera were not adequately established because miniature species present paedomorphic features that difficult the definition of homologies and consequently of their phylogenetic relationships. To circumvent this problem, some authors have suggested an approach comparing the anatomy of the miniaturized taxon to early ontogenetic stages of non-miniaturized related species to determine the heterochronic events involved in its evolution. This scope constitutes a new line of research for the miniature Characiformes of the neotropical region. An osteological study of Priocharax is being developed with the international collaboration between the laboratories of Prof. Dr. Mônica de Toledo-Piza (Instituto de Biociências - USP) and of Dr. Ralf Britz (Natural History Museum, London) aiming to access the anatomical features of Priocharax in the ontogenetic context within the Characidae. In a previous visit to the laboratory of Dr. Britz, the candidate had a first contact with the main methods used in the anatomical studies of larvae and miniature fishes. In this occasion, the osteological study of Priocharax was started based on ten available specimens. Despite of being restricted, this small sample allowed to raise significant questions regarding developmental truncation, sexual dimorphism and intraspecific variation, with respective taxonomic implications. To address the sampling limitation, an expedition was organized in October 2011 to the Upper Rio Negro, which resulted in 214 additional specimens of Priocharax adequately preserved. In the first visit of the candidate to the laboratory of Dr. Britz, a sketch of the ossification sequence of Salminus brasiliensis was also produced based on 86 specimens, but some events of the organogenesis of the skeleton were not completely established due to the restricted number of specimens examined until then. Recent partnerships with fish-farms have yielded additional specimens to complement this developmental series. At last, aiming at a broader comparative context, in this previous visit the candidate also prepared and analyzed the ossification sequence of Lebiasina bimaculata. To complete the inclusion of these data in the study, images and descriptions of the different anatomical complexes still need to be done. Therefore, it is proposed in the present project a three-months research internship at the laboratory of Dr. Britz (Natural History Museum, London) with the objective to finish the activities started in the previous part of this study (i.e., osteological study of Priocharax, ontogenetic study of Salminus, illustration and description of the ossification sequence of Lebiasina). (AU)

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Scientific publications (7)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
GEORGE M. T. MATTOX; MARTIN HOFFMANN; PETER HOFFMANN. Ontogenetic development of Heterocharax macrolepisEigenmann (Ostariophysi: Characiformes: Characidae) with comments on the form of the yolk sac in the Heterocharacinae. Neotropical Ichthyology, v. 12, n. 2, p. 353-363, . (12/01075-1)
MATTOX, GEORGE M. T.; HOFFMANN, MARTIN; HOFFMANN, PETER. Ontogenetic development of Heterocharax macrolepis Eigenmann (Ostariophysi: Characiformes: Characidae) with comments on the form of the yolk sac in the Heterocharacinae. Neotropical Ichthyology, v. 12, n. 2, p. 353-363, . (12/01075-1)
GEORGE M. T. MATTOX; ALESSANDRO G. BIFI; OSVALDO T. OYAKAWA. Taxonomic study of Hoplias microlepis (Günther, 1864), a trans-Andean species of trahiras (Ostariophysi: Characiformes: Erythrinidae). Neotropical Ichthyology, v. 12, n. 2, p. 343-352, . (12/01075-1)
MATTOX, GEORGE M. T.; BRITZ, RALF; TOLEDO-PIZA, MONICA. Osteology of Priocharax and Remarkable Developmental Truncation in a Miniature Amazonian Fish (Teleostei: Characiformes: Characidae). Journal of Morphology, v. 277, n. 1, p. 65-85, . (11/50282-7, 11/13735-3, 12/01075-1)
MATTOX, GEORGE M. T.; BRITZ, RALF; TOLEDO-PIZA, MONICA. Skeletal development and ossification sequence of the characiform Salminus brasiliensis (Ostariophysi: Characidae). Ichthyological Exploration of Freshwaters, v. 25, n. 2, p. 103-158, . (12/01075-1)
MATTOX, GEORGE M. T.; BRITZ, RALF; TOLEDO-PIZA, MONICA; MARINHO, MANOELA M. F.. Cyanogaster noctivaga, a remarkable new genus and species of miniature fish from the Rio Negro, Amazon basin (Ostariophysi: Characidae). Ichthyological Exploration of Freshwaters, v. 23, n. 4, p. 297-318, . (09/15075-0, 11/13735-3, 12/01075-1, 12/00063-0)

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