# A Historical Reassessment of the Authorship Year of Brachyteles arachnoides (Primates: Atelidae)

## TL;DR

This paper reevaluates the historical authorship of the primate species Brachyteles arachnoides, arguing that the correct date is 1809, not 1806, based on examination of a verified specimen.

## Contribution

The paper challenges the traditional 1806 authorship of Brachyteles arachnoides and establishes 1809 as the correct date with a verified holotype specimen.

## Key findings

- The 1806 description of Brachyteles arachnoides lacks verifiable material and is considered a nomen dubium.
- The 1809 description, based on specimen MNHN-ZM-2007-1475, is validated as the correct authorship date.
- Historical trade data suggests that 18th-century Jamaica likely hosted Colombian/Panamanian primates, not Brazilian ones.

## Abstract

The authorship of Brachyteles arachnoides has traditionally been ascribed to É. Geoffroy Saint‐Hilaire, 1806. However, É. Geoffroy Saint‐Hilaire's original description was based entirely on secondary accounts, namely, Browne's (1756) Simia 2 and Edwards' (1764) report of a brown, long‐limbed, and four‐fingered monkey, without directly examining specimens or illustrations. Browne's Simia 2 describes a large brown primate with a prehensile tail and four‐fingered hands in Jamaica, characteristics that could apply to either Ateles or certain Brachyteles populations. Edwards' account, meanwhile, references two four‐fingered “spider monkeys” observed in London but lacks sufficient detail for definitive taxonomic assignment. Historical trade data further undermine this link, as 18th‐century Jamaica likely hosted Colombian/Panamanian primates, with no evidence of Brazilian primate imports. Étienne Geoffroy Saint‐Hilaire obtained the first verifiable Brachyteles specimen only in 1808, seized during Napoleon's Lisbon campaign. His 1809 redescription, including an illustration and the specimen MNHN‐ZM‐2007‐1475, meets modern taxonomic standards, whereas the 1806 name, based solely on ambiguous accounts, fails ICZN criteria for type association. We argue that Ateles arachnoides É. Geoffroy Saint‐Hilaire, 1806, constitutes a nomen dubium, as it cannot be tied to verifiable material. Instead, we validate Ateles arachnoides É. Geoffroy Saint‐Hilaire, 1809, with MNHN‐ZM‐2007‐1475 as the holotype by monotypy. This redefinition stabilizes the species' nomenclature, anchoring it to a concrete specimen and Geoffroy Saint‐Hilaire's empirically grounded 1809 work. By resolving these historical ambiguities, we provide a clearer framework for understanding Brachyteles taxonomy and highlight the importance of type specimens in early primatological classifications.

Key historical milestones in the taxonomy of Brachyteles arachnoides. It begins with Browne's (1756) early depiction of Simia 2, “The Four‐fingered Monkey”, in Jamaica, followed by Edwards' (1764) account of a brown four‐fingered monkey in the streets of London. In 1806, Étienne Geoffroy Saint‐Hilaire named Ateles arachnoides based on these accounts. The classification was later refined after he examined a specimen from the Museu de Ajuda in 1808, culminating in a redescription in 1809.

The conventional attribution of Brachyteles arachnoides to Étienne Geoffroy Saint‐Hilaire (1806) is contested, as the original description relied solely on unverifiable secondary accounts and lacked direct examination of the specimens.Historical evidence suggests that Browne's Simia 2 and Edwards' “brown monkey” lack links to Brachyteles, likely referring to Ateles species from the Caribbean region, given the historical trade routes between Jamaica and mainland Central and South America.
Ateles arachnoides É. Geoffroy Saint‐Hilaire, 1809 is recognized as the correct authorship date of the Southern Muriqui, with MNHN‐ZM‐2007‐1475 designated as the holotype by monotypy, supported by a detailed description and illustration from 1809.

The conventional attribution of Brachyteles arachnoides to Étienne Geoffroy Saint‐Hilaire (1806) is contested, as the original description relied solely on unverifiable secondary accounts and lacked direct examination of the specimens.

Historical evidence suggests that Browne's Simia 2 and Edwards' “brown monkey” lack links to Brachyteles, likely referring to Ateles species from the Caribbean region, given the historical trade routes between Jamaica and mainland Central and South America.

Ateles arachnoides É. Geoffroy Saint‐Hilaire, 1809 is recognized as the correct authorship date of the Southern Muriqui, with MNHN‐ZM‐2007‐1475 designated as the holotype by monotypy, supported by a detailed description and illustration from 1809.