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We review the extent and nature of scientific knowledge of the Big-headed Amazon River Turtle, Peltocephalus dumerilianus, covering distribution, morphology, taxonomy, diet, behaviour, reproduction, and ecology. We discuss the phylogenetic position of the species and its evolutionary relationships with the other podocnemidids, comparing morphological, karyological and molecular information. Also, we describe the importance of this species and its relationship with traditional Amazonian communities, including capture techniques, uses, beliefs and taboos. Finally, we comment on the conservation status of the species and the urgent need for additional studies. Besides discussing and reinterpreting published data, we provide new information from recent genetic studies, field activities and captive observations.

Chelonians represent an important resource in the Amazon, either as a source of protein at the base of the food chain of aquatic and transition ecosystems, or in the dispersion of seeds of plants from floodplains and flooded forests. The consumption and predatory exploitation of their meat and eggs by local populations has been, and still is, one of the main threats to these animals. Community-based conservation projects allied to official protection programs have been restoring populations of chelonians of the genus Podocnemis throughout the Amazon since 1974. In this study, we analyzed the historical time series of protection data of Podocnemis expansa, P. unifilis, P. sextuberculata and P. erythrocephala in areas protected by the government and communities in the Amazonas state and northwest of Pará state. Between 1974 and 2019, 230,444 nests and 21,350,201 hatchlings of P. expansa, 170,076 nests and 3,229,821 hatchlings of P. unifilis, 647,715 nests and 6,410,092 hatchlings of P. sextuberculata and 24,617 nests and 168,856 hatchlings of P. erythrocephala were protected. Community protection schemes emerged in 1990, and covered 80.7% of the areas and produced 64.2% of P. unifilis hatchlings and 44.6% of P. sextuberculata hatchlings. The areas with the highest production of P. expansa remain under government protection (57.4%). Using the time series of production of nests and hatchlings per beach, logistic growth curves were estimated, and the values of r and K were compared between the two protection systems (government and community). Beaches controlled by the government showed higher support capacity in the production of nests (1,910.7 ± 1,035) and hatchlings (211,513 ± 93,031) of P. expansa and P. sextuberculata (81,160 ± 34,924 hatchlings). However, the communities were more efficient in protecting nests (r = 0.102 ± 0.2315) and hatchlings (r = 0.282 ± 0.166) of P. unifilis. Community-based protection and monitoring programs are an important component that should be incorporated by the government’s environmental agencies for the management and conservation of turtles in the Amazon.

Se analizaron cuarenta pares de ovarios de hembras adultas de Peltocephalus dumerilianus (Schweigger 1812), para establecer los cambios morfológicos mensuales producidos durante un año. Se llevaron a cabo exámenes macroscópicos de los oviductos y de los ovarios de especímenes que los habitantes ribereños del municipio de Barcelos, Amazonas, Brasil, utilizaron para su consumo, usando metodológicamente la medida del diámetro y conteo de los folículos ováricos y de los cuerpos lúteos. Los resultados muestran la presencia gradual de folículos acorde con la época reproductiva, resaltando que durante el último tercio del proceso, justo antes de la postura se hacen más evidentes; se analiza la relación existente entre el tamaño de la hembra y la masa ovárica, la cual es estadísticamente significativa (F (10,29)=3,655, p < 0,05). Se hace evidente la existencia de una jerarquía ovario folicular que demuestra que para esta especie solo es posible fisiológicamente una postura por año.Forty pairs of ovaries of mature female Peltocephalus dumerilianus (Schweigger 1812) were analyzed, to establish the morphologic monthly changes that take place during one year; we examined macroscopically the oviducts and the ovaries of specimens that the riverside inhabitants of the municipality of Barcelos, Amazons, Brazil, used for their consumption. We measured the diameter and recorded the number of enlarged ovarian follicles and corpora lutea. The results show the gradual enlargement of follicles in agreement with the reproductive period, observing that during the last third of the process; just before oviposition they become more evident. The positive relationship between the size of the female and the ovarian mass, is statistically significant (F (10.29)=3.655, p < 0.05). Follicullar sizes suggest that this species nests only once a year.

La alimentación es uno de los aspectos más importantes en la vida de los organismos. En el grupo de los quelonios acuáticos amazónicos del género Podocnemis este aspecto es descuidado para P. sextuberculata. En este trabajo se presentan los resultados de una investigación sobre la alimentación de esta especie en la Reserva de Desarrollo Sustentable Mamirauá-RDSM. Se analizaron 235 muestras de contenidos estomacales, 117 machos y 118 hembras. Para obtener muestras de contenido estomacal, se utilizó el método de lavado con agua. Los contenidos estomacales también fueron colectados por disecación de tracto digestivo. Materia vegetal fue el ítem predominante en la alimentación de P. sextuberculata. No hubo diferencia en la frecuencia de semillas en las temporadas de aguas bajas y altas de los ríos. En todos los hábitat el volumen total de las semillas fue muy alto. La especie está adaptada a los cambios de estación, siendo las áreas inundables el hábitat más apropiado, en relación a la abundancia de las especies de la familia Poaceae. La información obtenida destaca la importancia de proteger las especies vegetales y los hábitat usados por P. sextuberculata en la RDSM.