Hypopigmentation in mantled howler monkeys Alouatta palliata (gray 1849): First documented cases of whole‐body leucism in South America

Abstract

The existence of hypopigmentation like leucism is the result of genetic anomalies that might be enhanced by external factors such as pollution. This anomaly may reduce survival rates. Leucism has been recorded in wildlife, but overall, it is considered very rare. There have been few records of mantled howler monkeys with leucism in Mexico and Costa Rica, but whole‐body leucism in howler monkeys from South America was unknown. In this article, we report for the first‐time documented cases of whole‐body leucism in young individuals of mantled howler monkeys Alouatta palliata in an isolated remanent of tropical dry forest in southwestern Ecuador known as Cerro Blanco Protective Forest. In total, we found two juvenile individuals with leucism in October 2021. The report of howler monkeys with whole‐body leucism may be caused by two processes: inbreeding because of isolated populations, environmental pressure caused by pollution, or the interaction of both. Our findings also reveal that hypopigmentation is becoming more frequent in howler monkey populations along its distributional range. Therefore, it is important to promote research in this field to disentangle the causes of hypopigmentation and to consider a regional management strategy for the species.

First records of leucism in Leontocebus nigricollis graellsi (Primates: Callitrichidae)

“…According to the scientific literature, leucism in monkeys may be caused by two processes: inbreeding because of isolated populations (Aximoff et al, 2020;Aximoff & Vaz, 2016;do Vale et al, 2018;Guzmán Caro et al, 2018;López-Platas et al, 2021), environmental pressure caused by pollution, or the interaction of both (Barros-Diaz et al, 2022), conditions that we believe do not correspond to the records presented here. L. n. graellsi is a species frequently sighted in the Cuyabeno Reserve, which means that its population is large.…”

“…The few known reports of leucism in primates have been documented mostly in large species, particularly in the genus Alouatta (Aximoff & Vaz, 2016;Barros-Diaz et al, 2022;López-Platas et al, 2021), but also in Ateles (Guzmán Caro et al, 2018); in small primates, there are only a few reports for the genus Callithrix (Aximoff et al, 2020;do Vale et al, 2018). Therefore, in this short communication, we present the first reports of leucism in the genus Leontocebus.…”

“…Leucism is an atypical condition of recessive genetic origin that occurs as a consequence of mutations that affect the generation, distribution, and aggregation of the melanin pigment in the skin of many vertebrates and is particularly noticeable in mammals (Lamoreux et al, 2010). Although this condition has been frequently mentioned in various orders of mammals (Tirira & Arbeláez, 2020), reports in primates are extremely rare (Aximoff et al, 2020;Barros-Diaz et al, 2022;Ramos-Luna et al, 2022), even though they comprise a conspicuous group that is frequently sighted (Mittermeier et al, 2013).…”

Cordillera Chongón Colonche: un punto caliente de diversidad para la conservación de mamíferos en el occidente de Ecuador

“…However, we were able to ascertain that its target was a young monkey that had strayed from the group. This group of howler monkeys consisted of more than 20 individuals; interestingly, this was the same group where the presence of a full-body leucistic monkey had previously been documented (Barros-Diaz et al, 2022). Notably, the leucistic monkey chose to climb to the top of the trees and positioned itself against the light, which hindered our ability to distinguish it clearly.…”

“…Creating ecological corridors both within and outside the Cordillera Chongón Colonche will play a pivotal role in reestablishing a connection with the Chocó, offering genetic protection to mammal species present in western Ecuador. A clear example of this need is provided by Alouatta palliata populations in Bosque Protector Cerro Blanco, where leucistic individuals have been reported (Barros-Diaz et al, 2022). However, achieving this objective requires concerted efforts involving inter-institutional participation from both the public and private sectors of the country.…”