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| Plecturocebus parecis
Gusmão, Messias, Carneiro, Schneider, Alencar, et al., 2019.
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Abstract
In 2011, a distinct but unnamed form of titi, Plecturocebus, was re-discovered in the Chapada dos Parecis, a plateau in
the southern extreme of the Brazilian state of Rondônia. Here we describe it as a new species based on an analysis of morphological and molecular traits. It can be distinguished from all other species of the genus Plecturocebus by its generally grayish agouti
pelage. The limbs are grayish agouti on the outer surface, and grayish white on the inner surface; the breast, throat, and sideburns
are also grayish white; the dorsum is reddish chestnut, and the tail is gray, paler to white at the tip. A phylogenetic analysis of the
new species revealed a monophyletic clade with the four geographically closest species, and four scenarios of species delimitation
indicated that speciation was recent. The geographic distribution of the new species is still poorly defined. Most of the recorded
localities coincide with areas of higher elevation in the transition zone between the Amazon forest and the Cerrado savanna, in
southern Rondônia and western Mato Grosso, including part of the Chapada dos Parecis (Parecis Plateau), and extending into
the Aripuanã/Juruena and Aripuanã/Roosevelt interfluves. The range of the new species is in the area of the Amazon’s “Arc of
Deforestation”, where enormous tracts of forest are being destroyed for timber, colonization and industrial agriculture. It occurs
in the Juruena National Park and a few Indigenous protected areas. Based on the categories and criteria of the IUCN Red List,
this new titi should be considered Near Threatened.
Key words: Pitheciidae, Chapada dos Parecis, geographic distribution, morphology, genetics
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| Figure 6. Plecturocebus parecis sp. nov. and its geographically adjacent species to the east, P. cinerascens,
provided by Stephen D. Nash.
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Plecturocebus parecis sp. nov.
Synonyms: Callicebus cinerascens (Spix, 1823) (in part). Miranda Ribeiro, A. de. 1914. Hist. Nat. Zool. Publ. 84. Annexo n. 5, p.19. Commissão de Linhas Telegraphicas Estratégicas de Matto-Grosso ao Amazonas, Rio de Janeiro; Hershkovitz, P. 1990. Fieldiana, Zool. n.s. (55); Van Roosmalen et al. 2002. Neotrop. Primates (10 suppl.);
Callicebus moloch (Hoffmannsegg, 1807) (in part). Hershkovitz, P. 1990. Fieldiana, Zool. n.s. (55).
Callicebus brunneus (Wagner, 1842) (in part). Hershkovitz, P. 1990. Fieldiana, Zool. n.s. (55).
Diagnosis: The beard, sideburns, thorax, and anterior portion of the
anterior members of Plecturocebus parecis sp. nov. are grayish-white, as are the hands, feet, and distal portion of the tail
(Fig. 5). The general coloration of the new species is dark
grayish agouti, in particular on the flanks and external surface
of the members (Fig. 1), with a distinctly reddish chestnutcolored dorsal region (Fig. 4). This combination of external morphological traits confers the new species with a unique
appearance when compared with all other Plecturocebus
species.
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| Figure 5. Plecturocebus parecis from the forest reserve of the UHE Rondon II hydroelectric plant.
Photograph A by Alberto Caldeiras; photographs B, C and D by Manoel Pinheiro, and
photographs E and F by Fabiano Mattos.
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Natural history: Plecturocebus parecis sp. nov. has been the subject of two ecological studies at the type locality (Alencar 2011; Mattos 2016). They have shown that the behavior and ecology of the new species are typical of other titis of the genus Plecturocebus (see Bicca-Marques and Heymann 2013).
The group studied by Alencar (2011) was formed of a breeding pair and their immature offspring, which engaged in typical territorial behaviors, in particular the characteristic vocal duet at the beginning of the daily activity period. Infants were carried almost exclusively by the breeding male. The study group occupied a small home range, of only 5.5 ha, and had a predominantly frugivorous diet (70% fruit, 20% leaf, 8% insects, and 2% flowers; n = 4060 scan sample records), with the consumption of fruit declining during the dry season, when other items increased in importance.
Mattos (2016) recorded Plecturocebus parecis sp. nov. groups of up to six individuals, with a modal size of four. This study also emphasized the importance of ripe fruit pulp, seeds, and arils in the diet of the species, which is typical of Plecturocebus.
Etymology: The species’ epithet is a reference to the Chapada dos Parecis, or the Parecis Plateau, where the new species, Plecturocebus parecis sp. nov., was found.
Vernacular names: Miranda-Ribeiro (1914) reported that the Parecis people refer to the new species as “otôhô”. The non-indigenous residents of the region refer to the new species as “zogue-zogue”, the name given to titi monkeys throughout the Brazilian Amazon basin. We recommend the Parecis titi.
Conclusions:
The genetic, morphological, and zoogeographic evidence presented here are sufficient to denominate Plecturocebus parecis sp. nov., a taxon distinct from P. cinerascens, with which it had been synonymized historically (Miranda-Ribeiro, 1914). The findings of the present study indicate a recent speciation process, with P. cinerascens as the sister group. Following the recognition of this new taxon, the genus Plecturocebus is now composed of 24 species.
Almério Câmara Gusmão, Mariluce Rezende Messias , Jeferson Costa Carneiro , Horacio Schneider ,
Thiago Bento de Alencar, Armando Muniz Calouro, Júlio Cesar Dalponte, Fabio de Souza Mattos, Stephen
F. Ferrari, Gerson Buss, Renata Bocorny de Azevedo, Eduardo Marques Santos Júnior, Stephen D. Nash,
Anthony B. Rylands and Adrian A. Barnett. 2019. A New Species of Titi Monkey, Plecturocebus Byrne et al., 2016 (Primates, Pitheciidae), from Southwestern Amazonia, Brazil. Primate Conservation. 33; S. 1–15.
