Petrogale assimilis Ramsay, 1877e

Parnaby, Harry & Gill, Anthony C., 2021, Mammal type specimens in the Macleay Collections, University of Sydney, Zootaxa 4975 (2), pp. 201-252 : 236-238

Petrogale assimilis Ramsay, 1877e

Proc. Linn. Soc. N.S.W. (ser. 1) 1 (4), 360. (March 1877).

Description read at the 25th November 1876 meeting of the LSNSW.

Current name. Allied Rock-wallaby Petrogale assimilis Ramsay, 1877 following Jackson & Groves (2015).

Taxonomic status. Considered a valid species until Thomas (1888), who thought it was a synonym of P. penicillata ( Gray, 1827) . Regarded as a synonym for the ensuring century, either of P. inornata Gould, 1842c or P. penicillata , sometimes as a subspecies. Re-instated as a valid species by Calaby & Richardson (1988) and confirmed by subsequent studies, see review by Eldridge (1997).

Holotype. M.422, by subsequent determination. Skin mount, skull apparently in situ, adult female, collected early June 1875 by Chevert party. Several collecting parties operated concurrently on the island from 1st to 3rd June, as indicated in Macleay’s diary ( Horning 1994), and the collector of the holotype is not recorded.

Topotype.?M.423, subadult (near adult) male, skin mount.

Type locality. Palm Islands ( Ramsay 1877e) = Great Palm Island , Queensland .

Comments. The type series consists of the holotype only, a female suspected to be adult by Ramsay. In his original description, Ramsay (1877e; published March) twice stated his belief that the species was known from a unique specimen but later stated ( Ramsay 1877a: 11; published July) that two specimens were obtained from Palm Island during the Chevert Expedition, the other being a young animal for which he did not indicate the sex. The second specimen has no type status and is a topotype. Its identity amongst specimens now in the Collection remains unclear.

It is evident from the pencil annotations made to the MAMU 1890s Catalogue, and dated 1965, that attempts at that time to assign registration numbers against the original list of specimens in the 1890s Catalogue was problematic and unresolved. Given the confusion, we examine this in further detail. Species of eastern Queensland Petrogale can be difficult to distinguish on external features. Identification would have been more challenging during registration in the 1960s because P. assimilis was not recognised as a distinct species but as a synonym of P. inornata . The 1890s Catalogue listed two skins as P. assimilis (both female, one not fully adult) and eight as P. penicillata but confused species identifications during the 1960s registration resulted in three specimens being assigned M numbers against the two Palm Island P. assimilis . The MAMU Mammal Register marked two of these (M.422 and M.423) as “types” and as alternatives against the single adult female listed in the 1890s Catalogue, along with M.424 against the young adult female. Crucially, the sex was not recorded for the three specimens when assigned M numbers, otherwise it would have been evident that male skin M.423 could not be the holotype, a female. The other skin mount, an adult female M.424, labelled Palm Island and as having been collected on the Chevert Expedition, was identified as P. penicillata by Dr Tim Flannery. Incorrect locality data has evidently been assigned to that specimen, given that the species does not occur on Palm Island. Therefore M.423 is the only skin of P. assimilis from Palm Island now in the Collection other than M.422. That specimen remains problematic. Whereas the second specimen in the 1890s Catalogue is listed as a young female skin, M.423 is a young, near adult male. Either the incorrect sex was entered during compilation of the 1890s Catalogue; M.423 is not the topotype from Palm Island, or perhaps more than two individuals were collected from Palm Island.

Stanbury (1969) listed female M.422 as the holotype and we are confident that specimen is the original one examined by Ramsay. Stanbury (1969) noted that M.423 (male) from Palm Island was overlooked in Ramsay’s original account but Stanbury overlooked the subsequent statement by Ramsay (1877a), that there were two specimens only. Macleay’s ambiguous Chevert diary entry for the evening of 1st June 1875 offers no clarity on the number captured at Palm Island on that day: “..total captures of the day consisted of about 2 wallabys (a new species)...” ( Horning 1994).

Ramsay stated that his description was based on a well-prepared skin. His 15 external measurements were therefore taken on a skin already prepared as a mount and not a flat skin. Six of the 11 measurements that we assessed of skin M.422 are consistent with those given by Ramsay for the holotype ( Table 8 ). Some of his measurements, such as head length, are difficult to corroborate as they are poorly delineated on the skin. M.422 cannot be a match for three of his measurements. Length of toe does not equate to 2.1 inches (53.3 mm), irrespective of how it is measured nor can it be a misprint for 1.1 inches (27.9 mm). The intact right ear length and “snout to base of ear” are both about 0.2 inch (5.0 mm) short of Ramsay’s measurements. Perhaps the skin has shrunk. The MAMU vertebrate collection was stored for decades throughout the 20th century in temperature extremes in the Macleay Museum roof space ( Stanbury 1988; Fulton 2012).

The taxonomic literature has not cited the conclusion of Stanbury (1969) that the holotype is M.422. The type was considered to be unlocated by Calaby & Richardson (1988) and Eldridge & Close (1992). While this might seem to have been an oversight, it is likely that Calaby and Richardson were aware of the confused attempt to match Petrogale specimens during the 1960s registration of unnumbered specimens, and this could be the basis for their conclusion that the holotype had not been reliably identified. This confusion appears to have mislead Fulton (2016b), who relied on the Australian Faunal Directory database (apparently incorporating the conclusions of Calaby & Richardson (1988)). He mistakenly believed that the holotype was missing, although the specimen and the Register entry of its type status have remained unchanged in the Collection since Stanbury (1969). Reliable species identification by a specialist in Petrogale taxonomy has been a critical step in resolving the identity of Ramsay’s holotype amongst over a dozen specimens now in the MAMU. We were fortunate that such a specialist, Dr Mark Eldridge (Australian Museum) examined the Petrogale collection in December 2016 and corroborated the likely species identity of M.422 and M.423.