Ancient DNA of the pygmy marmoset type specimen Cebuella pygmaea (Spix, 1823) resolves a taxonomic conundrum.

The pygmy marmoset, the smallest of the anthropoid primates, has a broad distribution in Western Amazonia. Recent studies using molecular and morphological data have identified two distinct species separated by the Napo and Solimões-Amazonas rivers. However, reconciling this new biological evidence with current taxonomy, i.e., two subspecies, Cebuella pygmaea pygmaea (Spix, 1823) and Cebuella pygmaea niveiventris (Lönnberg, 1940), was problematic given the uncertainty as to whether Spix's pygmy marmoset ( Cebuella pygmaea pygmaea) was collected north or south of the Napo and Solimões-Amazonas rivers, making it unclear to which of the two newly revealed species the name pygmaea would apply. Here, we present the first molecular data from Spix's type specimen of Cebuella pygmaea, as well as novel mitochondrial genomes from modern pygmy marmosets sampled near the type locality (Tabatinga) on both sides of the river. With these data, we can confirm the correct names of the two species identified, i.e., C. pygmaea for animals north of the Napo and Solimões-Amazonas rivers and C. niveiventris for animals south of these two rivers. Phylogenetic analyses of the novel genetic data placed into the context of cytochrome b gene sequences from across the range of pygmy marmosets further led us to re-evaluate the geographical distribution for the two Cebuella species. We dated the split of these two species to 2.54 million years ago. We discuss additional, more recent, subdivisions within each lineage, as well as potential contact zones between the two species in the headwaters of these rivers.

On a new species of titi monkey (Primates: Plecturocebus Byrne et al., 2016), from Alta Floresta, southern Amazon, Brazil.

The taxonomy of the titi monkeys (Callicebinae) has recently received considerable attention. It is now recognised that this subfamily is composed of three genera with 33 species, seven of them described since 2002. Here, we describe a new species of titi, Plecturocebus, from the municipality of Alta Floresta, Mato Grosso, Brazil. We adopt an integrative taxonomic approach that includes phylogenomic analyses, pelage characters, and locality records. A reduced representation genome-wide approach was employed to assess phylogenetic relationships among species of the eastern Amazonian clade of the Plecturocebus moloch group. Using existing records, we calculated the Extent of Occurrence (EOO) of the new species and estimated future habitat loss for the region based on predictive models. We then evaluated the species' conservation status using the IUCN Red list categories and criteria. The new species presents a unique combination of morphological characters: (1) grey agouti colouration on the crown and dorsal parts; (2) entirely bright red-brown venter; (3) an almost entirely black tail with a pale tip; and (4) light yellow colouration of the hair on the cheeks contrasting with bright red-brown hair on the sides of the face. Our phylogenetic reconstructions based on maximum-likelihood and Bayesian methods revealed well-supported species relationships, with the Alta Floresta taxon as sister to P. moloch + P. vieirai. The species EOO is 10,166,653 ha and we predict a total habitat loss of 86% of its original forest habitat under a "business as usual" scenario in the next 24 years, making the newly discovered titi monkey a Critically Endangered species under the IUCN A3c criterion. We give the new titi monkey a specific epithet based on: (1) clear monophyly of this lineage revealed by robust genomic and mitochondrial data; (2) distinct and diagnosable pelage morphology; and (3) a well-defined geographical distribution with clear separation from other closely related taxa. Urgent conservation measures are needed to safeguard the future of this newly discovered and already critically endangered primate.

The cost-effectiveness of biodiversity surveys in tropical forests.

The identification of high-performance indicator taxa that combine practical feasibility and ecological value requires an understanding of the costs and benefits of surveying different taxa. We present a generic and novel framework for identifying such taxa, and illustrate our approach using a large-scale assessment of 14 different higher taxa across three forest types in the Brazilian Amazon, estimating both the standardized survey cost and the ecological and biodiversity indicator value for each taxon. Survey costs varied by three orders of magnitude, and dung beetles and birds were identified as especially suitable for evaluating and monitoring the ecological consequences of habitat change in our study region. However, an exclusive focus on such taxa occurs at the expense of understanding patterns of diversity in other groups. To improve the cost-effectiveness of biodiversity research we encourage a combination of clearer research goals and the use of an objective evidence-based approach to selecting study taxa.