Caluromys (Mallodelphys) derbianus (Waterhouse, 1841)

Voss, Robert S., 2022, An Annotated Checklist Of Recent Opossums (Mammalia: Didelphidae), Bulletin of the American Museum of Natural History 2022 (455), pp. 1-77 : 7-8

Caluromys (Mallodelphys) derbianus

(Waterhouse, 1841)

TYPE MATERIAL AND TYPE LOCALITY: LIVCM- D 194, the holotype by monotypy, is a female specimen of unstated age, originally mounted for exhibition, but subsequently remade as a study skin and skull ( Thomas, 1913; Largen, 1985; Fisher, 2002). The type locality is unknown, but it has often been assumed to be somewhere in the Río Cauca watershed of northern Colombia (e.g., by Allen, 1904; Thomas, 1913).

SYNONYMS: antioquiae Matschie, 1917; aztecus Thomas, 1913; canus Matschie, 1917 ; centralis Hollister, 1914; fervidus Thomas, 1913; guayanus Thomas, 1899; nauticus Thomas, 1913; pallidus Thomas, 1899 ; pictus Thomas, 1913; pulcher Matschie, 1917; pyrrhus Thomas, 1901; senex Thomas, 1913.

DISTRIBUTION: Caluromys derbianus is a transAndean species that occurs in lowland rainforest, dry forest, and montane (“cloud”) forest from Veracruz ( Mexico) throughout most of Central America to northwestern South America (Bucher and Hoffmann, 1980: fig. 3). In South America, the species is known from the Pacific littoral and adjacent Andean foothills of western Colombia and western Ecuador, but it is also known from the Caribbean lowlands of northwestern Colombia and from the interAndean valley of the Río Cauca ( Gardner, 2008: map 2). 3

REMARKS: Phylogenetic analyses of mtDNA sequence data suggest that Caluromys derbianus and C. lanatus are genetically divergent and reciprocally monophyletic species ( Voss et al., 2019), but most 19th and early 20th century authors (e.g., Thomas, 1913) regarded these taxa as conspecfic. Apparently, the first researcher to treat them as valid species was Gilmore (in Bugher et al., 1941), who mentioned ear color and differences in the extent of caudal pelage as distinguishing characters. However, because there is said to be some species overlap in caudal pelage traits ( Gardner, 2008: 5), and because pelage markings said to distinguish these species appear to be similarly unreliable ( Voss et al., 2019), only ear coloration seems to be diagnostically useful (the pinnae are unpigmented in derbianus versus blackish or purple in lanatus ). Although Bucher and Hoffman (1980: 1) claimed that C. derbianus is the “largest species in the genus,” measured series of C. derbianu s and C. lanatus exhibit broad morphometric overlap (R.S.V., personal obs.). Recent landmark-based multivariate morphometric analyses of Caluromys have either failed to convincingly distinguish C. derbianus and C. lanatus from one another ( López-Fuster et al., 2008) or have simply not addressed the problem (Fonseca and Astúa, 2015).

3 Insofar as I am aware, Caluromys derbianus and C. lanatus are allopatric, but several problematic records of C. derbianus mapped by Fonseca and Astúa (2015: fig. 2) merit comment because they imply geographic range overlap. One such Colombian record (their locality 69) is based on USNM specimens from the Río Raposo, which is in the Cauca valley, not (as mapped) in the Cordillera Oriental. A second Colombian record (locality 68) is based on FMNH specimens from the upper Río Sinú, which drains the western slopes of the Cordillera Occidental, not (as mapped) the northeastern slopes of the Serranía de San Lucas. A third problematic record (locality 71), mapped in the Cordillera Oriental of Ecuador, is based on AMNH 10058, a specimen from Costa Rica. A fourth anomalous record, from Tingo Maria in eastern Peru (locality 75), is based on a specimen (LSUMZ 17681) that is almost certainly misidentified ( C. derbianus is not known from Peru; Pacheco et al., 2020).

Some authors (e.g., Hall, 1981) have recognized valid subspecies of Caluromys derbianus , but there is a striking lack of mtDNA sequence variation among samples collected in Costa Rica, Panama, and Ecuador ( Voss et al., 2019). Broader geographic sampling of genetic variation is needed to determine whether any of the nominal taxa herein treated as synonyms of C. derbianus represent evolutionarily significant units worthy of taxonomic recognition.