Several mammal inventories have been reported from the lowland Amazon of Madre de Dios, Peru, but few have been reported for the Las Piedras River. Here we present a list of mammal species from the Las Piedras River. Over a period of seven years (2013–2020), we recorded the presence of mammal species, excluding bats and small rodents, using camera traps and opportunistic sightings. Our study area was near the Huascar-Las Piedras River confluence, 58 km north of the Madre de Dios River and covering an area of 22,430 ha. We recorded 60 species belonging to seven orders, 26 families, and 53 genera, including novel records for the Las Piedras tributary. Notable records reported include Leopardus cf. tigrinus (Schreber, 1775), Galictis vittata (Schreber, 1776), Saguinus imperator subgrisecens (Lönnberg, 1940), Cebuella niveiventris (Lönnberg, 1940), Cyclopes thomasi (Linnaeus, 1758), Coendou ichillus Voss & da Silva, 2001, and Caluromys lanatus (Olfers, 1818).

Rhabdophis helleri envenomations may cause lethal coagulopathy, yet the venom mechanisms are poorly characterized. This study investigated the procoagulant mechanisms of R. helleri venom, with particular focus on coagulation factor activation and cofactor dependencies. We demonstrate that R. helleri venom potently activates Factor VII (FVII) and Factor X (FX) in a highly cofactor-dependent manner. FVII activation was minimal with venom alone but increased dramatically with the addition of the cofactor protein Factor V (FV) and reached maximal activity with the addition of the cofactor Factor Va (FVa). In addition to using endogenous thrombin produced FVa, the itself is able to convert FV into a useable FVa product. Similarly, FX activation was greatly amplified in the presence of FV or FVa, and showed similar cofactor dependence and the ability to use venom-activated FVa. Under comparable FV or FVa cofactor conditions, FX was activated at substantially lower magnitude than Factor VII, suggesting that Factor VII is the primary pathophysiological target. Systematic calcium and phospholipid requirement analysis revealed extremely high levels of dependence upon both cofactors. This is the first time for any venom that such a high level of phospholipid dependence has been noted. These results represent the first documentation of Factor Va-dependent zymogen activation in a non-front-fanged species, indicating convergent evolution of this mechanism across Natricidae, Elapidae, and Viperidae snake families. The determination of the biochemistry underpinning the rapid plasma clotting induced by the venom provides mechanistic insight into the consumption coagulopathy observed clinically in human envenomations and the stroke-inducing effect in prey. These toxicological findings advance understanding of rear-fanged snake venom evolution and inform development of treatment strategies for this understudied but medically important species.

Literature on the predation ecology of Amazonian canids is scarce, especially for the two rarely observed canids; Speothos venaticus (Bush Dog) and Atelocynus microtis (Short-eared Dog). Between 2000 and 2005 we documented one observation of predation of a A. microtis from southeastern Peru and an observation of S. venaticus predation from southwestern Brazil.

Mammalogy Notes. Publicación de la Sociedad Colombiana de Mastozoología (SCMas)

While elucidating the evolutionary trajectory of green anacondas, we previously documented the existence of two distinct species, Eunectes akayima sp. nov. and Eunectes murinus (Linnaeus, 1758), that separated approximately 10 million years ago. Our research integrates a novel molecular clock approach, focuses on tectonic plate movements with fossil records as minimal chronological markers, and offers a refined understanding of speciation events in relation to major biogeographical occurrences in South America. Mitochondrial DNA analysis demonstrates a significant genetic divergence between the species, which is supported by a notable difference in sexual size dimorphism (SSD) intensity between the two species, along with other morphological differences. This paper also rectifies earlier oversights in the description of the new species and clarifies taxonomic ambiguities in compliance with the International Code of Zoological Nomenclature (henceforth ICZN). In addition, we designate a neotype for E. murinus to stabilize the group. In an effort to honor Indigenous nations, E. akayima sp. nov. derives its name from the Carib language, advocating for the inclusion of traditional names in scientific discourse. Our paper not only contributes to the taxonomic stability of anacondas but also advocates for the usage of Indigenous names in zoological nomenclature by adopting a more inclusive and flexible approach to the ICZN and eliminating unintended exclusionary practices that we have inherited in science as in other disciplines.

Desert vipers (Eristicophis and Pseudocerastes) employ diverse procoagulant strategies despite their close phylogenetic relationships, yet the biochemical mechanisms underlying the variations in their coagulotoxic activities remain poorly understood. We conducted comprehensive coagulation factor activation studies across all four species in the clade: Eristicophis macmahoni (Ema), Pseudocerastes fieldi (Pfi), P. persicus (Ppe), and P. urarachnoides (Pur). Plasma clotting assays revealed extreme variation in coagulation speed (17.3-376.1 s), with E. macmahoni and P. urarachnoides emerging as rapid coagulators. Fluorometric zymogen activation studies demonstrated that all species require Factor Va as a cofactor for optimal activity, with species-specific preferences for either the endogenous form of Factor Va produced by circulating thrombin or the FVa produced by the venom directly cleaving Factor V. This suggests that the venoms cleave FV at sites distinct from the cleavage site utilised by endogenous thrombin. The species had dramatically distinct patterns of factor activation: Factor XII was most strongly activated factor, and had a venom rank order of Pur ≫ Ema > Pfi = Ppe; Factor X was the next most potently activated factor, with a venom rank order of Ema = Pfi > Pur > Ppe; followed by Factor VII Pfi > Ppe > Ema = Pur; and prothrombin (Factor II) Ema > Pur, with activation by Pfi or Ppe not detectable. None of the venoms activated Factor XI. Notably, despite being suggested as a bird-specialist, P. urarachnoides exhibiting the highest Factor XII activation capacity is significant as avians have secondarily lost FXII as a component in their coagulation cascade. As such, the potent activation of FXII suggest non-avian prey species such as lizards or small rodents make up a significant proportion of this species diet. Antivenom efficacy studies revealed species-specific patterns, with the VINS Jorven antivenom showing superior neutralization against P. urarachnoides and Eristicophis macmahoni relative to the Inosan Inoserp-MENA antivenom and National Antivenom and Vaccine Production Centre of Saudi Arabia antivenom. These toxicology findings reveal that despite morphological similarity and shared ecological niches, desert vipers have evolved fundamentally distinct coagulotoxicity approaches to prey immobilization. These species-specific pathophysiological profiles have important clinical implications for antivenom development and bite treatment protocols in endemic regions.