Didelphis marsupialis Linnaeus, 1758

Feijó, Anderson & Voss, Robert S., 2019, A Neotype for Didelphis marsupialis Linnaeus, 1758, American Museum Novitates 2019 (3923), pp. 1-12 : 5-9

Didelphis marsupialis Linnaeus, 1758

NEOTYPE: An adult female specimen in the Royal Ontario Museum ( ROM 113908 , original number F40983 ; fig. 3 ), consisting of a skin, skull, postcranial skeleton, pouch young preserved in alcohol, and frozen tissues. A large (657 bp) fragment of the mitochondrial gene encoding cytochrome oxidase 1 ( COI) was amplified and sequenced from this specimen by ROM researchers and has been deposited in GenBank with accession number MG 828824 .

TYPE LOCALITY: The neotype was collected at the Brownsberg Nature Park headquarters (4°57 ʹ N, 55°11 ʹ W, 500 m above sea level), Brokopondo District, Surinam, on 11 April 2002

4 This is not quite accurate because Seba’s (1734) “Thesaurus” was sold in both colored and uncolored versions ( Engel, 1937), and the uncolored plates are not informative about ear pigmentation. It is not known whether the colorists who tinted the plates had access to the specimens from which the original drawings were actually made. In fact, it is to be doubted that the opossum in the colored version of plate 39 (reproduced by Dias et al., 2018: fig. 1 ) was rendered accurately, because its fur is brownish, whereas species of Didelphis have grayish or blackish fur. Additionally, the colorized plate does not show the prominent black-and-white caudal marking that is exhibited by all species in the genus ( Voss and Jansa, 2009).

by a field crew that included M.D. Engstrom, B.K. Lim, S.L. Peters, F.M. Catzeflis, and M. Djosetro. Local habitats and the mammalian fauna of the Brownsberg Nature Park were described by Lim et al. (2005), who listed eight other specimens of Didelphis marsupialis collected in the park, all of which can be considered topotypes.

REMARKS: The neotype skin agrees in all essential morphological details with Husson’s (1978) detailed external description of Didelphis marsupialis . Salient features include its entirely blackish ears, indistinct facial markings, and a bicolored tail that is furred only near the base (for approximately one-fiπh of its length). 5 External measurements (taken in the field) include total length (888 mm), tail length (463 mm), hind foot (including claws, 68 mm), and ear length (from notch, 57 mm); the specimen weighed 1250 grams.

Craniodental traits of the neotype conform to the generic description provided by Voss and Jansa (2009: 116–118). Selected craniodental measurements (taken as described and illustrated by Voss et al., 2018) include condylobasal length (98.1 mm), nasal length (47.0 mm), nasal breadth (12.4 mm), least interobital breadth (17.0 mm), least postorbital breadth (11.9 mm), zygomatic breadth (47.2 mm), palatal length (59.3 mm), palatal breadth (30.1 mm), maxillary toothrow length (41.7 mm), length of M1–M4 (20.1 mm), length of M1–M3 (16.5 mm), and width of M3 (6.0 mm).

The neotype of Didelphis marsupialis is strikingly unlike specimens of D. imperfecta (also known to occur in the Brownsberg Nature Park; Lim et al., 2005), which are substantially smaller in both external and craniodental dimensions and have white-tipped ears, more sharply defined facial markings, and longer-furred tail bases ( Mondolfi and Pérez-Hernández, 1984).

DUE DILIGENCE: The Code requires that we state why we think that the previous namebearing specimen of Didelphis marsupialis is lost or destroyed ( ICZN 1999: Article 75.3.4). Unfortunately, tracking down every possible location where the lectotype might be is a daunting task, because Seba’s material was widely dispersed in the centuries following the 1752 auction of his collection. According to Boeseman (1970), who carefully reviewed all of the existing documents pertaining to this event and to subsequent transfers of ownership, Seba’s zoological specimens are known to have been acquired by at least 11 European museums, of which one (in Groningen) was destroyed by fire, which only slightly simplifies matters. The remaining 10 museums are those in Amsterdam, Berlin, Bremen, Copenhagen, Leiden, London, Paris, Stockholm, Utrecht, and St. Petersburg.

Because the importance of Seba specimens as potential Linnaean types has long been known to taxonomists, and because all the major museums in these cities are (or were) centers of active zoological research, it seems unlikely that any 18th-century specimen convincingly identifiable as the opossum illustrated by Seba would have remained undetected to the present day; nor, having been identified as such, is it likely that its significance as lectotype would have been overlooked by the European research community. Unfortunately, Seba’s mammals were not distinctively labelled, and their identity can only be inferred from original containers (e.g., antique glass jars hermetically sealed with red wax) and particular resemblances to the individuals depicted in Seba’s plates ( Thomas, 1892). In the absence of such indications (the origi-

5 The furry tail base (90 mm) was measured in the field by F. Catzeflis (personal commun.). nal containers having been discarded, for example, or fluid-preserved specimens having been dissected), it seems unlikely that any material can now be confidently identified as Seba’s. Therefore, we assume that the lectotype of Didelphis marsupialis , if it does not appear in lists of type material at museums where it might reasonably be expected to have survived on documentary evidence, is either lost or unidentifiable. Of the 10 museums mentioned above, the likeliest to have Seba’s mammals based on Thomas’s (1892), Engel’s (1961), and Boeseman’s (1970) narratives are those in London, Leiden, Paris, and St. Petersburg.

The largest single trove of Seba’s mammals is preserved in the Natural History Museum in London—formerly the British Museum (Natural History)—which acquired it by purchase in 1867. Thomas (1892) explained the details by which he identified 26 fluid-preserved (“spirit”) specimens that closely correspond to illustrations in Seba (1734). Although these included several opossums (e.g., BMNH 67.4.12.542 [lectotype of Marmosa murina ] and BMNH 67.4.12.540 [holotype of Monodelphis brevicaudata ]; Voss et al., 2001), there were no specimens of Didelphis marsupialis among them, nor has subsequent curatorial activity at the Natural History Museum turned up any specimen that can now be positively identified as the lectotype ( Jenkins and Knutson, 1983).

The Naturalis Biodiversity Center in Leiden includes the collections formerly held by the Rijksmuseum van Natuurlijke Historie (RMNH) and the Zoological Museum Amsterdam (ZMA). Both museums were major recipients of Seba material through multiple purchases and donations ( Boeseman, 1970). Although Naturalis currently preserves one of Seba’s opossums (RMNH 25421 [lectotype of Philander opossum ]; Voss et al., 2001), it does not have any type material of Didelphis according to collection manager Steven van der Mije (personal commun.), who is currently supervising the publication of a type catalog compiled by Chris Smeenk, the late RMNH mammal curator.

Aπer the 1752 auction a significant part of Seba’s collection passed into the zoological cabinet of the Stadholder William V at the Hague, but much of this material was carted off as war booty by French revolutionary troops, who overran Holland in 1795 ( Thomas, 1892; Holthuis, 1969; Boeseman, 1970). In Paris, the stolen specimens were integrated into the collections of the Muséum National d’Histoire Naturelle (MNHN), with the result that, decades later, most of them were no longer recognizable as having belonged to the Stadholder; in particular, some mounted specimens had deteriorated and numerous fluid-preserved specimens had been dissected ( Pieters, 1980). Although some specimens were subsequently returned to Holland by way of restitution, others are known to have remained in Paris ( Holthuis, 1969; Boeseman, 1970). We do not know whether or not any of Seba’s mammals still exist in the Muséum National d’Histoire Naturelle, but none of the MNHN specimens mentioned by Geoffroy St.-Hilaire (1803)—whose catalog notably included specimens plundered by French troops from museums in other occupied countries—are certainly identifiable as the lectotype of Didelphis marsupialis , nor was any nomenclaturally relevant material of Didelphis listed by Beaufort (1966) or Julien-Laferrière (1994) in their lists of Paris museum marsupial types.

A substantial number of Seba’s zoological specimens are thought to have been purchased at the 1752 auction by agents acting for the Russian czar, and at least some of these presumably ended up at the Zoological Institute of the Russian Academy of Sciences ( Boeseman, 1970). However, a catalog of the Zoological Institute’s mammalian types ( Abramov et al., 1992) included no didelphid material.

We have made reasonable bibliographic and online efforts to find the lectotype of Didelphis marsupialis in other European collections, but without success. Although we cannot altogether discount the possibility that it still exists in some obscure museum attic or cellar, Boeseman’s (1970) account suggests that much of Seba’s material has been lost, destroyed, or rendered unrecognizable over the years. Our unsuccessful efforts to find the lectotype lead us to believe that it has suffered one or another of these melancholy fates.

Figures

FIGURE 1. The lectotype of Didelphis marsupialis, reproduced from an uncolored copy of Seba (1734: pl. 39) in the library of the American Museum of Natural History.

FIGURE 3. Neotype of Didelphis marsupialis (ROM 113908).