Occurrence of parasitism promoted by Myzobdella lugubris Leidy, 1851 (Annelida: Piscicolidae) in Callinectes bocourti (Crustacea: Portunidae): A report of invasive leech in Brazilian Amazon province.

This study reports the presence of high parasitic load by Myzobdella lugubris Leidy, 1851 in the swimming crab Callinectes bocourti A. Milne-Edwards, 1879 from Amazon mangrove. We sampled the swimming crabs using a baited trap, between January and June 2023, in Santa Maria River, located in the municipality of Curuçá, state of Pará, Brazil (geographical coordinates 0°40'3.705"S, 047°54'43.405"W). After sampling, each swimming crab was individually placed in plastic containers for the count of leeches per individual. In the laboratory, the specimens were sexed, measured (parasite and host) and fixed in 70% alcohol. For the leech species identification, macroscopic techniques were combined with light microscopy (LM) and scanning electron microscopy (SEM). We examined 86 specimens of C. bocourti (75 males and 11 females) in a ratio of 1 M:0.14 F, all infested with leeches. In total, 186 leech specimens were collected, ranging from 1 to 21 leeches per host. Leeches oviposited the cocoons in greater quantities in ventral area of swimming crab carapace (32%), followed by dorsal area of carapace (29.09%), chelipeds (24.34%) and ambulatory legs (14.57%). The presence of M. lugubris is a risk to the health of the host, once it may transmit a range of diseases to aquatic organisms, and subsequently risk to human health.

Redescription of Brevimulticaecum baylisi () (Nematoda: Heterocheilidae), a parasite of Caiman crocodilus (Crocodylia: Alligatoridae) in the north-eastern Peruvian Amazon.

Caiman crocodilus is among the most abundant and widely distributed predators in the Neotropical region. These animals consume prey such as crustaceans, birds, small mammals, reptiles, amphibians, and fish, which can carry infective larval forms of nematodes. Brevimulticaecum has few studies on its morphology available, lacking detailed images. Therefore, the aim of this study was to redescribe Brevimulticaecum baylisi, stomach parasite of Caiman crocodilus, from subsistence hunting in the Yavari-Mirin River, Peruvian Amazon, using light and scanning electron microscopy. Four caimans were analyzed, and, macroscopically, all had ulcerative lesions in the stomach caused by this parasite. Histopathology showed an inflammatory infiltrate with a predominance of lymphocytes. Morphological characteristics of nematodes include the presence of three diamond-shaped lips wider than they are long, interlabia pyramidal, excretory pore located above the nerve ring, present intestinal cecum, ventriculus with five ventricular appendages, and long, winged spicules. These morphological characters, added to the number and distribution of the pre- and postcloacal papillae of the male specimens, allowed the identification of these parasites as B. baylisi. Scanning electron microscopy of these nematodes showed the presence of a dentigerous ridge on the inner surface of the lips in both sexes, while in males, the presence of a horseshoe-shaped median papilla was observed on the upper lip of the cloaca. Our research, therefore, adds these characteristics to the original description of B. baylisi, in addition to expanding the biogeographical distribution of this parasite.

Diversity of endohelminths parasitizing bred Muscovy ducks Cairina moschata domestica (Anseriformes: Anatidae) from the eastern Brazilian Amazon.

Raising of Muscovy ducks Cairina moschata domestica for subsistence of human populations is common in northern Brazil, although their helminth infections have been poorly investigated, despite the possible presence of helminths with zoonotic potential. The aim of this study was to investigate the diversity of parasite endohelminths in C. moschata domestica raised in the Marajó Island region, state of Pará, Brazilian Amazon region. Of 33 specimens examined, 90.9% were parasitized by one or more parasite species, for a total of 926 parasites recorded. The species mean richness of endohelminths varied from 0 to 6, and there was a predominance of hosts with 1 to 2 species of parasite endohelminths and low prevalence and low abundance of parasites. This was the first report of larvae of Anisakis sp., Contracaecum sp., Hysterotylacium sp., Raphidascaris sp., Eustrongylides sp., Syngamus sp., Ascocotyle sp. and Athesmia heterolecithodes for C. moschata domestica. The parasitic community of C. moschata domestica was composed of 11 species, with a high species richness for nematode species and a small number of digeneans.