Mazama nemorivaga (Cuvier, 1817) is a gray brocket deer that inhabits the Amazon region. An assessment of previous studies revealed inconsistencies in its current taxonomic classification, suggesting the need for an update in its genus classification. A taxonomic repositioning of this species is proposed through the collection of a specimen from its type locality (French Guiana) with subsequent morphological (coloring pattern, body measurements, and craniometry), cytogenetics (G Band, C Band, conventional Giemsa, Ag-NOR staining, and BAC probe mapping), and molecular phylogenetic analysis (mitochondrial genes Cyt B of 920 bp, COI I of 658 bp, D-loop 610 bp), and comparisons with other specimens of the same taxon, as well as other Neotropical deer species. The morphological and cytogenetic differences between this and other Neotropical Cervidae confirm the taxon as a unique and valid species. The phylogenetic analysis evidenced the basal position of the M. nemorivaga specimens within the Blastocerina clade. This shows early diversification and wide divergence from the other species, suggesting that the taxon should be transferred to a different genus. A taxonomic update of the genus name is proposed through the validation of Passalites Gloger, 1841, with Passalites nemorivagus (Cuvier, 1817) as the type species. Future research should focus on evaluating the potential existence of other species within the genus Passalites, as suggested in the literature.

The Yucatan brown brocket deer was initially described as Mazama pandora Merriam, 1901. Phylogenetic analysis of mitochondrial DNA recovered the species as sister group of the genus Odocoileus and subsequently the species was repositioned to this genus naming Odocoileus pandora (Merriam, 1901). However, there is still a lack of taxonomic consensus that could assist in nomenclature definition of the species. We aim to clarify the taxonomy of O. pandora through an integrative assessment using morphological, cytogenetic, and molecular data from recently collected specimens. Morphological characterizations identified O. pandora as a medium-sized brocket deer. The skull shows an inflated auditory bulla and a narrow zygomatic arch. Males present long, broad, spike-like antlers converging inward, marked with deep longitudinal grooves. Odocoileus pandora shows a karyotype with 2 n = 60 FN = 74. Bacterial artificial chromosome clone hybridization showed that centric and tandem fusions, and inversions are involved in karyotypical divergences between O. pandora, S. gouazoubira, M. americana, and O. virginianus. Our phylogeny based on Bayesian Inference of mitogenome recovered O. pandora as monophyletic within the subtribe Odocoileina, with Odocoileus as sister taxa. Morphological and genetic characteristics of O. pandora agrees in differencing the Yucatan brown brocket from Mazama and Odocoileus genera. Therefore, a new generic name should be indicated for this taxon.

Sampling skin fragments has been an important strategy for genetic studies and ex situ conservation, aiding in the preservation of genetic diversity in Neotropical deer and other wild species. From the moment of collection in the field, transport media must ensure tissue viability by providing the necessary nutrients until laboratory processing for culture or cryopreservation. This study aimed to evaluate the effects of temperature and storage duration on tissue viability and cell growth using two types of skin transport media: Dulbecco's modified Eagle medium (DMEM) supplemented with 15% fetal bovine serum and 0.9% physiological saline solution. Skin fragments were collected from the inguinal region of five captive gray-brocket deer (Subulo gouazoubira) and divided into small samples, which were randomly assigned to each transport medium. The samples were stored at 5°C and 24°C for 24 and 72 hours, followed by cryopreservation and thawing to assess histomorphology, apoptosis (TUNEL test), cell growth, viability (Trypan blue and MTT assay), and mitotic index. The results showed that physiological saline solution is as efficient as DMEM in maintaining tissue viability, with 80% of viable cells observed and no significant difference after storing in different skin transport media (p > 0.05). Cell morphology and apoptosis did not change in response to media, temperature, or storage duration. We recovered metaphases from all skin tissue storing conditions, with a similar mitotic index to those presented in other cell culture studies from deer biopsies. These results showed the feasibility of storing skin tissue samples during 24 and 72 hours at 5°C and 24°C in different transport media guaranteeing the cell growth and viability for genetic studies and reproductive biotechnologies. The study may contribute to sampling collection in places where displacement with large equipment is limited, allowing the establishment of simplified skin transport protocols as an important step to accessing genetic material from individuals inhabiting isolated localities.

The Neotropical region is currently facing a critical period of biodiversity loss, with deer species (family Cervidae) being particularly affected by severe habitat degradation, genetic bottlenecks, and population fragmentation. In this context, germplasm biobanks emerge as strategic tools for conservation efforts. This article presents a comprehensive review of the Deer Research and Conservation Center germplasm bank, the largest repository of genetic material for Neotropical deer worldwide. We detail the diversity of species represented, the types and quantities of cryopreserved samples, and the operational costs associated with maintaining the biobank. Additionally, we discuss the main advantages of germplasm banking, such as preserving genetic diversity without the logistical challenges of managing large captive populations, as well as critical challenges, particularly those arising from ongoing taxonomic uncertainties that complicate species identification and sample management. Scientific applications and conservation actions already enabled by this resource are presented, alongside a discussion of future perspectives, including potential expansions of sample types and integrative genomic analyses. This review underscores the essential role of germplasm biobanks in preserving the genetic legacy of Neotropical deer and supporting long-term biodiversity conservation strategies.