Abstract
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.
Highlights
Pygmy marmosets (Cebuella) are the smallest of all living anthropoid primates
Using the mitochondrial cytochrome b gene and ddRAD nuclear genome sequences from geographically representative samples from both sides of the Solimões River, Boubli et al (2018) recovered two highly supported clades that diverged 2.25 million years ago (Ma), leading the authors to suggest the existence of two species of Cebuella; one comprising pygmy marmosets sampled on the northern side of the Solimões and the other comprising samples collected on the southern side
The sequence from Spix’s holotype grouped with contemporary animals sampled in Tabatinga on the north bank of the Solimões River, and other localities north of the Amazon/Solimões, including the Japurá River, while the pygmy marmoset from the south bank of the Solimões, near Benjamin Constant, grouped with the second clade
Summary
Pygmy marmosets (Cebuella) are the smallest of all living anthropoid primates. They have a wide geographic distribution across the upper Amazon region in northwestern Bolivia, Brazil, Peru, Ecuador, and southern Colombia. Johann Baptist von Spix described pygmaea based on a pet pygmy marmoset given to him, probably by a local Tikuna Indian, during his visit to the upper Solimões River on the Brazilian-Colombian border (von Spix, 1823; von Spix & von Martius, 1824) He assigned the type locality as near Tabatinga, a small village in Brazil, near the Colombian border on the left bank of the Solimões. In 1940, Lönnberg described niveiventris as a distinct pygmy marmoset from the Lago Ipixuna, approximately midway between the Tefé and Purus rivers, a little west of Coarí on the right (south) bank of the Solimões (Lönnberg, 1940) To describe this new taxon, he compared his type series with specimens collected by the Olalla brothers near the Brazilian village of Eirunepé ( known as Joāo Pessoa) on the right bank of the Juruá River (see Boubli et al, 2018). He affirmed that the Spix’s type came from the right bank of the Solimões, and the opposite bank of Tabatinga (Lönnberg, 1940)
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