This study investigated the structure and diversity of the endohelminth community and its interactions with Pseudoplatystoma fasciatum, caught in the Aquidauana River, in the State of Mato Grosso do Sul, Brazil. Ten helminth species were represented in 1,228 specimens of parasites found in the intestine and mesentery of 33 specimens of P. fasciatum. Cestodes were observed in the intestine, while nematodes Cucullanus sp. in the mesentery. Contracaecum sp. Type 1, Spatulifer rugosa and Choanoscolex abscisus showed the highest mean intensity and mean abundance and Nomimoscolex sudobin showed the highest prevalence. Simpson's index indicated dominance in the endohelminth infracommunities (C = 1.0792) and Choanoscolex abscisus was considered the central species. A clumped pattern of dispersion according to Green's index was related. 69.69% of hosts analyzed had between 2 and 5 species of endohelminths. Mean diversity was H = 0.5517 (SD = 0.4209). Two pairs of species showed significant positive association and four pairs presented significant positive correlation among abundance data. Significant negative correlations between total length and prevalence and abundance of Peltydocotyle rugosa and Nomimoscolex sudobim were found. However, no significant correlation was observed between condition factor and abundance, as well as total length and diversity. There was significant prevalence of Harriscolex kaparari in male hosts. Keywords

In this study the structure and diversity of the endohelminth community, as well as its interactions with 73 specimens of Piaractus mesopotamicus are described. The fish were caught in Aquidauana and Miranda rivers, both located in the Pantantal region, in the state of Mato Grosso do Sul. A total of 608,788 specimens of helminthes were found, representing five species: Dadaytrema oxycephala, Chabaudinema americanum, Spectatus spectatus, Rondonia rondoni and Echinorhynchus jucundum. D. oxycephala was more prevalent (91.78%) followed by R. rondoni (73.97%).

During the INVEMAR - MACROFAUNA I expedition (1998-1999), specimens of 16 species of crustacean decapods of the Galatheidae family, belonging to three genera, were collected. In this paper the distictive characteristics of 12 of the species, registered for the first time for the Colombian Caribbean, are presented. This paper also includes taxonomic keys, species images, bathymetric and geographic data and comments of their morphological variations. Additionally, the holdings of the family, collected in Colombian localities and deposited in biological collections, according to the reviewed bibliographical references, are listed. The species are: Agononida longipes (A. Milne-Edwards, 1880); Munida constricta A. Milne-Edwards, 1880; M. evermanni Benedict, 1901; M. flinti Benedict, 1902; M. forceps A. Milne-Edwards, 1880; Munidopsis alaminos Pequegnat and Pequegnat, 1970; M. brevimanus (A. Milne-Edwards, 1880); M. erinaceus (A. Milne-Edwards, 1880); M. longimanus (A. Milne-Edwards, 1880); M. platirostris (A. Milne-Edwards and Bouvier, 1894); M. polita (Smith, 1883); and M. ramahtaylorae Pequegnat and Pequegnat, 1971.

Six slipper lobsters (Crustacea: Scyllaridae) are reported from the Colombian Caribbean and a diagnosis for each species, and a key for their identification is included. It reported for the first time from this area: Scyllarides aequinoctialis, S. delfosi, Scyllarus depressus and Parribacus anctarcticus.

The genus Munida is one of the most diverse within the superfamily Galatheoidea. This genus also represents one of the richest and most abundant decapod crustaceans from the continental shelves and upper slopes of the Caribbean and Pacific coasts of Colombia. A morphological study of species of this genus showed taxonomic difficulties mainly due to the lack of topological correspondence of some of the diagnostic characters, confusion in the nomenclature and poor or incomplete descriptions of some species. The majority of the species belonging to the genus Munida found in the tropical Atlantic and eastern Pacific oceans were analyzed. Based on the topological correspondence of several external morphological characters of the examined species, a standardization of the nomenclature of the diagnostic characters for species identification is proposed.