New records and modelling the impacts of climate change on the black-tailed marmosets

protection of the areas forming the current and future habitat of this species through such measures as protected area creation. Introduction Threats to global biodiversity have reached unparalleled levels, with the majority caused directly or indirectly by human activities [1, 2]. Since they threaten the survival of taxonomic groups in diverse ecosystems, such occurrences represent an unprecedented challenge for con- servationists planet-wide [3–7]. Prominent among these is climate change, which is being accelerated by industrial activities and changes in land use [3]. While the impacts of climate change on scientifically-described species are alarming, their potential impact on species for which knowledge is still limited is also of great concern. Such losses are incalculable due to the many knowledge gaps in terrestrial biodiversity. This includes gaps in such basic information as the abundance (Prestonian shortfalls), evolutionary patterns (Darwinian shortfalls), limits of species traits (Raunkieran shortfalls), form of biotic interac- tion (Eltonian shortfalls), abiotic tolerances of species (Hutchinsonian shortfalls),species distri- bution patterns (Wallacean shortfalls), and the taxonomic delimitation of species (Linnean shortfalls) [8, 9]. Such gaps present a particular challenge for those who wish to understand species distribution patterns so as to develop effective conservation strategies [10]. Such issues are aggravated in megadiverse regions, such as the tropics, where species richness per unit area is greatest, but overall knowledge is poor [3].

Basic questions of taxonomy and distribution exist even for high-profile groups such as pri- mates, especially for smaller-bodied species. For Neotropical primates, for example, despite the increase in the general number of studies, the species Mico nigriceps [11] (Primates: Calli- trichidae) remains one of the least-known primates, with a lack of even basic information, such as geographic distribution and general ecology [11]. The original description of M. nigri- ceps [11] indicated the geographic distribution was unknown in its entirety, with only two locations being confirmed in the Madeira-Marmelos interfluvium, on the mid-section of the Madeira river, in the Brazilian states of Amazonas and Rondoˆnia. Prior to this, Mico popula- tions from the head of the Ji-Parana´/Machado river had been allocated to M. emiliae [12], based on studies of specimens collected during studies by the Integrated Development Pro- gram of Northwest Brazil (POLONOROESTE). These were collected in the district of Nova Brası´lia (today the municipality of Ministro Andreazza, Rondonia State), and their taxonomic allocation was followed by subsequent studies [11, 13–15]. Mico nigriceps has the general color pattern characteristic of the argentatus group [11]: the body is silvery-gray, with the coat dark- ening on the posterior and ventral parts of the body; the dark pigmentation of the face and ears is a diagnostic characteristic of the species; the general pattern is for black extremities; the arm, mantle and belly have light brown and orange tones, the back is brown, and the hind

limbs brownish-orange; the tail is completely black [11]. Nearly three decades after its scientific description, M. nigriceps is still little-known scientifi- cally. Current knowledge of the species is limited to that given by Ferrari and Lopes [11], plus subsequent additional data-points [16]. Accordingly, an expansion of knowledge of the spe- cies, its ecology and true distribution, thus minimizing the effects of Wallacean and Linnean shortfalls, is highly desirable, especially given that the species appears on the Brazilian List of Endangered Species as Data Deficient (DD) [17]. In addition, the extent of habitat destruction in the region where the species occurs has been severe, especially in recent years, as policies of PLOS ONE Modeling of Mico nigriceps PLOS ONE | https://doi.org/10.1371/journal.pone.0256270 September 7, 2021 2 / 14 any direct financial benefits that may result from the publication. Competing interests: No authors have competing intests.