Marmosops (Marmosops) noctivagus (Tschudi, 1844)

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 : 59-61

Marmosops (Marmosops) noctivagus

(Tschudi, 1845)

VOUCHER MATERIAL (TOTAL = 38): Nuevo San Juan (AMNH 272704, 272715, 272775, 272782, 272809, 273034, 273051, 273058, 273060, 273061, 273131; MUSM 11032–11036, 11038, 11041, 11042, 11044, 11048, 13288–13292, 15301–15305, 15314), Orosa (AMNH 73853, 73854), San Pedro (UF 30451–30454), Santa Cecilia (FMNH 87122).

OTHER INTERFLUVIAL RECORDS: Jenaro Herrera ( Fleck and Harder, 1995).

IDENTIFICATION: Like other material traditionally referred to Marmosops noctivagus (e.g., by Tate, 1933; Patton et al., 2000; Voss et al., 2004; Hice and Velazco, 2012), specimens from the Yavarí-Ucayali interfluve are rather large mouse opossums (table 24) with mostly selfwhitish ventral fur and conspicuously beaded interorbital regions, but without distinct postorbital processes at any age or in either sex. 11 As

11 A few old adult males (e.g., MUSM 15305, AMNH 73853) have indistinct processes.

reported by Díaz-Nieto et al. (2016), DNA sequences from specimens with these phenotypic traits form a geographically widespread clade that extends across much of western Amazonia and along the adjacent eastern foothills and lower slopes of the Andes. However, this clade includes several allopatric haplogroups, which differ among themselves by about 3%–5% in mean uncorrected sequence comparisons at the cytochrome b locus. Sequenced specimens from the Yavarí-Ucayali interfluve belong to the haplogroup that Díaz-Nieto et al. (2016) called “ noctivagus C,” which (in their analyses) also included other sequences from south of the Amazon in western Brazil, eastern Peru, and northeastern Bolivia. Although the “ noctivagus C” haplogroup is widespread in lowland habitats, it is also known to extend to at least 2200 m above sea level in southeastern Peru (e.g., near Amaybamba in Cuzco department; Díaz-Nieto et al., 2016: appendix, locality 98).

Eleven nominal taxa are currently regarded as synonyms of Marmosops noctivagus (e.g., by Voss and Jansa, 2009), but it is currently difficult to determine the application of names to most of the haplogroups discovered by Díaz-Nieto et al. (2016), a problem that those authors discussed at

TABLE 24

some length. The difficulty arises both from the lack of unambiguously diagnostic characters by which to distinguish taxa in the M. noctivagus complex and from the lack of sequence data from many type localities. Although geographically distant samples of M. noctivagus often exhibit modest morphological differences, such differences are hard to interpret in the absence of data from geographically intermediate sites and in the absence of relevant genetic information. Our material from the Yavarí-Ucayali interfluve, for example, averages larger in most measured dimensions than specimens collected near the type locality of M. noctivagus (in the Andean foothills of Junín department; Gardner, 2008), 12 but the differences

12 For example, AMNH 230005, 230007–230013.

we observed are insufficient as a basis for taxonomic distinction, and we have no sequence data from the vicinity of the type locality, which is not, in fact, far outside the known geographic range of the “ noctivagus C” haplogroup.

In the absence of a comprehensive revision of the Marmosops noctivagus complex based on better morphological samples and denser molecular sequencing than those available to us at present, it seems profitless to speculate about trinomial nomenclature. However, it is relevant for the purposes of this report to note that sequences obtained from specimens collected on the left (“north”) bank of the Amazon (e.g., at the Estación Biológica Allpahuayo; fig. 1) belong to a different mtDNA haplogroup than those from the Yavarí-Ucayali interfluve, from which they differ by about 3.9% at the cytochrome b locus (Díaz-Nieto et al., 2015: table S4). Because the left-bank haplogroup (“ noctivagus A”) also occurs in eastern Ecuador, the type locality of the nominal taxon politus Cabrera, 1913, that epithet would seem to apply to it if there were any point in recognizing subspecies. However, measurements and side-by-side comparisons of our vouchers with left-bank specimens (e.g., the LACM and TTU specimens reported by Hice and Velazco, 2012) did not reveal any consistent morphological differences between them.

ETHNOBIOLOGY: The Matses do not distinguish this species from other pouchless, longtailed, black-masked species of small opossums (all known as chekampi; see the account for Marmosa , above) and therefore have no particular beliefs about it.

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

REMARKS: Of 25 specimens accompanied by definite habitat information, 13 (52%) were taken in primary upland (unflooded) forest, 10 (40%) were taken in secondary growth (abandoned swiddens), and 2 (8%) were captured in houses. Of 12 specimens accompanied by substrate information, 9 (75%) were trapped on the ground or on fallen logs, 2 (17%) were trapped on lianas between 1.5 and 1.8 m above the ground, and one was taken by hand as it perched close to the ground on a small tree. A single specimen was taken in the daytime from a leaf nest in the crown of an Astrocaryum palm at an unrecorded height above the ground, and another specimen was found dead, but all the specimens shot or captured by hand while active were taken at night, and all of the specimens trapped by D.W.F. and R.S.V. were found at dawn in traps that had been baited in the late afternoon of the previous day.