Monodelphis (Pyrodelphys) emiliae (Thomas, 1912)

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 : 38-41

Monodelphis (Pyrodelphys) emiliae

(Thomas, 1912)

Figure 12

VOUCHER MATERIAL (TOTAL = 7): Jenaro Herrera (AMNH 276721, MUSM 23807), Nuevo San

Juan (AMNH 268221; MUSM 11065, 13298), Río Aucayo (FMNH 58955), San Pedro (MUSM 22333).

OTHER INTERFLUVIAL RECORDS: Quebrada Curacinha (photograph, fig. 12).

IDENTIFICATION: Our voucher material exhibits all of the distinctive phenotypic traits of the monotypic subgenus Pyrodelphys , including disruptively colored dorsal pelage (a reddish head and rump separated by grizzled-grayish middorsal fur), contact or fusion of the thenar and first interdigital pads of the hind foot, a rounded but distinct frontal process of the jugal, parietal-mastoid contact, exposure of the basioccipital in the rear of the orbit, a broadly rounded rostral tym- panic process of the petrosal, broad lower-molar anterior cingulids, and distinct entoconids on m1–m3 ( Pavan and Voss, 2016).

A cytochrome b sequence from MUSM 13298 was analyzed by Pavan et al. (2014), who recovered it as part of a strongly supported haplogroup with other specimens that exhibit the diagnostic morphological traits of Monodelphis emiliae . Although substantial phylogeographic structure was reported among the sequences that Pavan et al. (2014) identified as M. emiliae , morphological comparisons of our Peruvian specimens with the holotype and other material from eastern Amazonia have not revealed any consistent differences. At least for the time being, we recognize M. emiliae as a widespread and morphologically uniform species.

According to Pine and Handley (1984: 242), Monodelphis emiliae has “well-defined postorbital processes on the frontals,” but among the specimens we examined this trait is developed in just a few old adult males (e.g., BMNH 20.7.14.44, MUSM 20452). By contrast, females and other adult males (some of which have wellworn teeth; e.g., FMNH 58955) lack any trace of frontal processes. The same authors (op. cit.: 241) described the tail of M. emiliae as “furred throughout its length,” but only the base of the tail bears soft fur on the specimens we examined, the remainder of that organ being covered with the usual caudal bristles (albeit thicker, longer, and more densely crowded than in many other congeneric species). The measurements of M. emiliae reported by Patton et al. (2000: table 15) include several values that are smaller than any obtained by us (table 13) or by Pine and Handley (1984); although we have not examined all of Patton et al.’s material, at least one of their measured specimens (MVZ 190335) is a subadult. This species is one of the few didelphid species that is polymorphic for presence/absence of secondary foramina ovales, which are formed by stout medial bullar laminae in some specimens (e.g., AMNH 96810, MUSM 20452), but not in others (e.g., AMNH 268221, BMNH 20.7.14.44). The fugitive ventral coloration origi- nally reported by Thomas (1912a) and subsequently noted by Pine and Handley (1984), Patton et al. (2000), and Pavan and Voss (2016: fig. 14) was also seen in our fresh material. The ventral fur of MUSM 2083 (an adult female), for example, was bright pink in life (on 27 May 1998), but it soon faded to a dull beige on the dried skin. Although sample sizes are small, it seems noteworthy that adult males and adult females in our Peruvian material have nonoverlapping measurements for many craniodental dimensions (table 13).

ETHNOBIOLOGY: The Matses do not distinguish this species from other short-tailed opossums (all known as yama; see the account for Monodelphis , above) and therefore have no particular beliefs about it.

TABLE 13

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

REMARKS: Of the five specimens we collected, one (AMNH 268221) was captured in a Matses house surrounded by secondary vegetation; another (MUSM 11065) was captured by hand in old secondary vegetation near a Matses swidden; another (MUSM 13298) was trapped on the ground in valley-bottom primary forest; a third (MUSM 23807) was trapped on the ground in primary forest growing on white sand; and the last (AMNH 276721) was taken in a pitfall in swampy primary forest. The specimen from San Pedro was trapped “on a hilltop in a primary terra firme forest” ( Valqui, 2001). Based on these observations, it would seem that Monodelphis emiliae is a habitat generalist, although Patton et al.’s (2000) trapping results suggest that it might not occur in seasonally flooded forests. One of our specimens (MUSM 13298) was taken on the same date, along the same trapline, and in the same habitat (primary upland rainforest) as a specimen of M. peruviana (AMNH 272695). Consistent with the Matses’ observation that short-tailed opossums are diurnal, MUSM 11065 was captured by hand at 07:30 hrs, and MUSM 13298 was found at 17:00 hrs in a trap that had previously been checked and found empty at dawn.

Although Monodelphis emiliae was reported from the “Iquitos area” by Patton et al. (2000), all the specimens known to have been collected in northeastern Peru are from the right (“south”) bank of the Amazon. 9 Despite many decades of collecting near Iquitos—on the left 9 Note that, due to the river’s convoluted course, the right bank of the Amazon near Iquitos is actually the east side and the left bank is the west side (fig. 2, inset). To avoid confusion, however, we use “south” and “north” with respect to the river’s macrogeographic orientation.

(“north”) bank of the river—including the impressive faunal survey effort monographed by Hice and Velazco (2012), no specimens or sightings of M. emiliae have been reported from there. Nor has M. emiliae , which is very widely distributed along the right bank of the lower Amazon ( Pine and Handley, 2008: map 41), been reported to occur at any other leftbank locality. Thus, it seems reasonable to conclude that the Amazon effectively limits the northward distribution of this species.

OTHER SPECIMENS EXAMINED (TOTAL = 12): Brazil — Amazonas, Igarapé Porongaba (MVZ 190335), Seringal Condor (MVZ 190334); Pará, Baião (AMNH 96810), Boim (AMNH 37491, BMNH 11.12.22.16 [holotype]), Vila Braga (BMNH 20.7.14.44). Peru — Cusco, Cashiriari (MUSM 14146, 14148), Pagoreni A (MUSM 36686), San Martín (MUSM 14149); Loreto, Cerros de Canchaguaya (MUSM 18028), Cerros de Contaya (MUSM 20452).

Figures

FIG. 12. Bothriopsis taeniata (Serpentes: Viperidae) eating Monodelphis emiliae at Quebrada Curacinha, Loreto, Peru (photo and observation by Roosevelt García). Although no voucher specimen was preserved, M. emiliae is unambiguously identifiable in the photograph by its diagnostic dorsal coloration (see text).