Hyladelphys kalinowskii ( Hershkovitz, 1992 )

Voss, Robert S., Fleck, David W. & Jansa, Sharon A., 2019, Mammalian Diversity And Matses Ethnomammalogy In Amazonian Peru Part 3: Marsupials (Didelphimorphia), Bulletin of the American Museum of Natural History 2019 (432), pp. 1-89 : 20-23

Hyladelphys kalinowskii ( Hershkovitz, 1992)

Figures 9A , 10A

VOUCHER MATERIAL (TOTAL = 2): Nuevo San Juan (AMNH 276725; MUSM 11031).

OTHER INTERFLUVIAL RECORDS: None.

IDENTIFICATION: This tiny marsupial, long unknown to science and only recently recognized as the sole survivor of an ancient lineage, is still represented by fewer than two dozen museum specimens despite its wide Amazonian distribution and apparent lack of habitat specificity ( Hershkovitz, 1992; Voss et al., 2001; Jansa and Voss, 2005; Astúa, 2006; Hice and Velazco, 2012; Catzeflis, 2018). Our two specimens consist of the damaged skull of a juvenile that retains the diagnostically reduced milk dentition ( Voss et al., 2001: figs. 17, 18), and the fluid-preserved carcass and extracted skull of an adult female.

Díaz (2014) erroneously reported that the latter specimen (AMNH 276725) was collected at Jenaro Herrera.

Hyladelphys kalinowskii is one of three superficially similar species in our region, all of which are very small (<30 g) opossums with long tails, black masks, and reddish-brown dorsal fur. Despite these resemblances, they are only distantly related to one another, and specimens in hand are easily identified by numerous integumental and craniodental differences (figs. 9, 10; table 4). Traits unique to H. kalinowskii among this trio of tiny didelphids include the posterior extent of its blackish facial markings, possession of just four mammae, an indistinctly banded tail (due to paler skin over the vertebral articulations), lack of a premaxillary rostral process, absence of a posterior accessory cusp on C1, a third upper premolar (P3) that is conspicuously smaller than P2, and an exceptionally short upper molar row (LM ≤4.6 mm). Hyladelphys kalinowskii additionally differs from Marmosa lepida by its exclusively self-white ventral fur and lack of postorbital processes. Hyladelphys kalinowskii additionally differs from Gracilinanus emiliae by having a much shorter tail, and by lacking a gular gland, palatine fenestrae, and secondary foramina ovales.

Both of our specimens conform in all qualitative traits to the emended description of Hyladelphys kalinowskii provided by Jansa and Voss (2005). Measurements of our adult female specimen are a bit smaller than those of the adult female holotype from Cuzco department and the adult female paratype from Junín (table 5), but without any adequate population sample to assess individual (nongeographic) variation in this species, such differences are hard to interpret. Although Jansa and Voss (2005) discussed the possibility that multiple species of Hyladelphys might be represented among the specimens currently referred to H. kalinowskii , ours are so similar to Hershkovitz’s (1992) original material that this identification would seem to be beyond dispute.

TABLE 4

ETHNOBIOLOGY: The Matses do not distinguish this species from other pouchless, longtailed, black-masked species of small opossums, all of which are known indiscriminately as chekampi (see the account for Marmosa , below). Therefore, they have no particular beliefs about it, nor is it of any cultural importance.

MATSES NATURAL HISTORY: The Matses have no definite knowledge of this species.

REMARKS: Our juvenile specimen was captured during the day by a Matses boy when it ran out of some leaf litter. 4 Another was captured by a Matses hunter in unknown circumstances.

OTHER SPECIMENS EXAMINED (TOTAL = 5): French Guiana —Paracou (AMNH 267003, 267338, 267339). Peru — Cuzco, Hacienda

4 Although the original phrasing of the Matses conversation that elicited this information was not recorded, the usual term for leaf litter is shapu, which can either refer to a thick layer of dead leaves on the ground or to an accumulation of dead leaves in the crown of a stemless palm (typically 1–2 m above the ground). Unfortunately, this ambiguity cannot now be resolved, but the latter interpretation would be more consistent with what is currently known about the nesting habits of Hyladelphys ( Catzeflis, 2018) .

Cadena (FMNH 89991 [holotype]; Junín, Chanchamayo (FMNH 65754).

Figures

FIG. 9. Dorsal and ventral cranial views of three small opossums. A, Hyladelphys kalinowskii (AMNH 267338, an adult male from French Guiana); B, Marmosa lepida (AMNH 273186, an adult male from the Yavarí- Ucayali interfluve); C, Gracilinanus emiliae (MUSM 15292, an adult female from the Yavarí-Ucayali interfluve). Abbreviations: amp, anteromedial process of the alisphenoid bulla (enclosing a secondary foramen ovale); pal, palatine fenestra; pop, postorbital process (of frontal); rp, rostral process (of premaxilla).

FIG. 10. Lateral cranial views of three small opossums (same specimens as in fig. 9). A, Hyladelphys kalinowskii; B, Marmosa lepida; C, Gracilinanus emiliae. Abbreviations: P2, second upper premolar; P3, third upper premolar; pac, posterior accessory cusp (of upper canine); rp, rostral process (of premaxilla).