Marmosops chucha, Díaz-Nieto & Voss, 2016

Díaz-Nieto, Juan F. & Voss, Robert S., 2016, A Revision Of The Didelphid Marsupial Genus Marmosops, Part 1. Species Of The Subgenus Sciophanes, Bulletin of the American Museum of Natural History 2016 (402), pp. 1-72 : 56-58

Marmosops chucha , new species

Figures 25–27

HOLOTYPE: CTUA 434 (original number CACE004 ), consisting of the skin, skull, fluidpreserved carcass, and associated tissues of an adult female collected by Camilo A. Calderón- Acevedo on 15 July 2010 at Hacienda Vegas de La Clara (fig. 28: locality 18), municipio Gómez Plata, Antioquia, Colombia.

DISTRIBUTION, HABITATS, AND SYMPATRY: Examined specimens of Marmosops chucha are from west of the Río Magdalena in northern Colombia between 130 m and 1400 m; known collection localities are in the foothills of the Ser- ranía de Abibe (the northwestern terminus of the Cordillera Occidental), the northeastern part of the Cordillera Central, and the interandean valley of the Río Porce (fig. 28). Recorded capture habitats include premontane rain forest ( Sánchez-Giraldo and Díaz-Nieto, 2015), premontane moist forest ( Estrada-Pareja et al., 2007), and lowland rain forest ( Castaño and Corrales, 2010), all of which now occur as fragments within an anthropogenic matrix of pastures and agricultural fields. At the upper limit of its known elevational range, M. chucha occurs sympatrically with M. handleyi (e.g., near Valdivia [appendix 1: locality 24]; see Díaz-N. et al., 2011).

DESCRIPTION: Body pelage brownish (near Prout’s Brown in darker specimens, closer to Dresden Brown in others) middorsally, indistinctly paler laterally, and about 7–10 mm long at midback; ventral pelage continuously selfwhite from chin to groin (usually including the insides of the fore- and hind limbs), but selfwhite fur narrowed by lateral zones of gray-based abdominal fur (tipped with brown) in some specimens. 16 Manus covered dorsally with uniformly pale hairs (the metacarpals not contrasting sharply in color with the digits); lateral carpal tubercle bladelike, not spoon shaped. Mammary formula 4–1–4 = 9 in all examined females with visible teats. Tail substantially longer than combined length of head and body (mean LT/HBL × 100 = 130%), usually indistinctly bicolored and sometimes indistinctly paler distally than basally.

Nasals not very long (usually not extending posteriorly behind the lacrimals) and much wider posteriorly than anteriorly (laterally expanded at the maxillary-frontal suture). Lacrimal foramina concealed from lateral view inside anterior orbital margin; zygomatic process of squamosal broadly overlapped dorsally by the jugal. Palatine fenestrae absent or minute. Dorsolateral margin of ethmoid foramen formed by the orbitosphenoid.

16 This might be a sexually dimorphic trait. The midventral zone of self-white fur—measured across the sternum—seems to be wider in females (17–20 mm, N = 3) and narrower in males (7–12 mm, N = 5).

Upper canines short in both sexes but apparently sexually dimorphic: males usually with only posterior accessory cusp and females usually with both anterior and posterior accessory cusps (MHNUC 986, a male with both anterior and posterior accessory cusps, and FMNH 69822, a female with just a posterior accessory cusp, are exceptions). Upper third molar (M3) anterolabial cingulum narrowly continuous with preprotocrista (anterior cingulum complete). Lower canine (c1) premolariform (procumbent, with posterior accessory cusp) and small, subequal in height to p1; c1 anterolingual accessory cusp absent in most examined material (but dis- tinctly present in FMNH 70925). Entoconid of m1 shorter than adjacent m2 paraconid; unworn m4 talonid with three distinct cusps.

COMPARISONS: Comparisons of Marmosops chucha with M. bishopi , M. juninensis , and M. ojastii have already been provided in the accounts for those species (above).

Marmosops chucha and M. magdalenae are similar in most qualitative and morphometric traits, but palatine fenestrae are consistently absent or indistinct in M. chucha , whereas these openings are consistently large in M. magdalenae . Additionally, the dorsolateral margin of the ethmoid foramen is usually formed by the orbitosphenoid in M. chucha whereas the dorsolateral margin of this foramen is usually formed by the frontal in M. magdalenae . Lastly, there are apparent taxonomic differences in the presence of C1 accessory cusps: in M. chucha most males have only posterior accessory cusps and most females have both anterior and posterior cusps, whereas in M. magdalenae both sexes have only posterior accessory cusps.

ETYMOLOGY: From chucha , a colloquial term for “opossum” in Colombian Spanish (Comisión de Lingüística de la Academia Colombiana, 2012), here treated as a noun in apposition.

REMARKS: The known geographic ranges of Marmosops chucha and M. magdalenae are separated by the Río Magdalena, an important geographic barrier ( Chapman, 1917; Gutiérrez-Pinto et al., 2012), and they differ from one another by about 5.9% in average uncorrected pairwise comparisons of partial cytochrome- b sequences. Although additional phenotypic and genetic evidence that these are fully differentiated species would be welcome, the results at hand seem sufficient to justify their recognition as such in the context of this revision.

The material that we refer to Marmosops chucha was previously identified as Marmosa parvidens by Pine (1981), as Marmosops parvidens by Díaz-N. et al. (2011), and as Marmosops “West Magdalena ” by Díaz-Nieto et al. (2016a).

SPECIMENS EXAMINED (N = 10): Colombia — Antioquia, Amalfi (CTUA 428), Gómez Plata

(CTUA 434), Valdivia (FMNH 69822, 69825, 69826), Villa Arteaga (FMNH 69837); Caldas, Norcasia (MNHUC 750, 986), Samaná (FMNH 70925; MNHUC uncataloged DCV69).

Figures

FIG. 25. Dorsal views of skulls of Marmosops ojastii (left, USNM 371299), M. chucha (center, CTUA 434), and M. magdalenae (right, ICN 19924). All views about ×3.

FIG. 26. Ventral views of skulls of Marmosops ojastii (left, USNM 371299), M. chucha (center, CTUA 434), and M. magdalenae (right, ICN 19924). All views about ×3.

FIG. 27. Lateral views of skulls of Marmosops ojastii (above, USNM 371299), M. chucha (center, CTUA 434), and M. magdalenae (below, ICN 19924). All views about ×3.