Monodelphis touan (IEPA, 1154)

Pavan, Silvia Eliza, Rossi, Rogerio Vieira & Schneider, Horacio, 2012, Species diversity in the Monodelphis brevicaudata complex (Didelphimorphia: Didelphidae) inferred from molecular and morphological data, with the description of a new species, Zoological Journal of the Linnean Society 165 (1), pp. 190-223 : 201-202

MONODELPHIS TOUAN ( SHAW, 1800)

Type information: Holotype lost, from ‘Cayenne’, French Guiana. Neotype FMNH 21720, designated by Voss et al. (2001), an adult male from Cayenne, 04 ° 56′N, 52 ° 20′W ( Gardner, 2008) preserved as skin and skull. Collected by S. Klages on 26.ii.1917.

Synonyms: Viverra Touan Shaw, 1800 ; Mustela touan Bechstein, 1800 ; Mustela touan Daudin in Lacépède, 1802; Didelphis tricolor Geoffroy, 1803 .

Morphological diagnosis: Same as for the M. brevicaudata complex with the following additions: HBL averages 137 mm in adult females and 159 mm in adult males (Supporting Information Table S2). Dorsal pelage with grizzled, grey coloured stripe at mid-dorsum, contrasting with reddish sides ( Fig. 4 ); head pelage reddish laterally, with mid-dorsal stripe narrow, sometimes ill-defined, confined by a band of red hairs above each eye; underparts greyish cream, sharply differentiated from the reddish sides ( Fig. 4 ); throat and chin distinctly reddish; tail dorsally covered with body fur to about one third of the caudal length; ventrally, body fur coverage is limited to the tail’s connection with the body. CBL averages 35.5 mm in adult females and 39.8 mm in adult males; interorbital region relatively narrow ( Fig. 5 ); zygomatic arches slightly convergent anteriorly; maxillopalatine foramina relatively short ( Fig. 5 ); UMS averages 7.8 mm in adult females and 8.0 mm in adult males (Supporting Information Table S2).

Geographical distribution: North-eastern South America, from French Guiana and the Brazilian state of Amapá southward to the Brazilian state of Pará south of the Amazon river and east of the Xingu river, including Marajó Island ( Fig. 6 ). Specimens of M. touan from south of the Amazon river were found in sympatry with specimens of M. glirina in the municipality of Marabá, in south-eastern Pará. Both species were caught in the same line of pitfall traps at Serra dos Carajás (A. C. M. Oliveira, UFPA – Universidade Federal do Pará, Belém, Brazil, pers. comm.), indicating syntopy for them.

Geographical variation: Specimens from localities south of the Amazon river are effectively distinguished from specimens from north of the Amazon river by exhibiting broader mid-dorsal stripe on head, coverage of the tail by body fur extending only about one fifth (in contrast to one third or one half) of caudal length, darker colour of tail (the portion not covered by body pelage), ears, and feet. Cranially, when comparing individuals from the same sex and age class, specimens from south exhibit larger molars, larger bulla, and slightly broader braincase and nasals.

Amongst specimens from the north of the Amazon river, the extension of body fur on the dorsal surface of the tail corresponds to about one third of caudal length in specimens from Amapá, and to about one half of caudal length in specimens from French Guiana. Specimens from Amapá also have skulls slightly longer when compared to French Guianan specimens, which show proportionally broader skulls.

Remarks: Based on Buffon’s (1789) description of Le Touan, with type locality in Cayenne, French Guiana, Shaw (1800) described Viverra touan . Shaw noted a blackish dorsal fur, ferrugineous sides and white lower parts, being the first reference to a tricoloured specimen of the M. brevicaudata group. Mustela touan Bechstein, 1800 and Mustela touan Daudin in Lacépède, 1802 were also based on Buffon’s specimen, and are objective synonymies of Viverra touan . Geoffroy (1803) described Didelphis tricolor based also on a tricoloured specimen from Cayenne ( MNHN 1990.421). Until now, D. tricolor has been regarded as a synonym of M. brevicaudata (e.g. Thomas, 1888; Cabrera, 1919; Gardner, 2005; Pine & Handley, 2008). Our new taxonomic arrangement, however, implies that D. tricolor should be considered as a synonym of M. touan .

The association of the name M. touan to the specimens from the eastern clade of our molecular analyses is explained by the morphological similarity of the neotype of V. touan Shaw, 1800 ( FMNH 21720) with those specimens. Our genetic samples of this clade include specimens from Cayenne, the type locality of the nominal taxa. The resurrection of M. touan to include the eastern clade is supported by the monophyly and genetic distinctiveness of this group, allied to a morphological differentiation from the species M. brevicaudata (sensu stricto).

Amongst the haplotypes of the eastern clade, the ones from the Brazilian state of Pará (localities south of the Amazon river) were regarded as Monodelphis species ‘D’ by Pine & Handley (2008). These specimens are morphologically distinct from specimens from the north of the Amazon river (see the Geographical variation section above), and form a strongly supported, truly monophyletic lineage that is embedded amongst haplotypes from French Guiana and the state of Amapá, Brazil (north of the Amazon river) in most analyses, rendering a paraphyletic group of northern specimens in most analyses ( Fig. 2 ). However, the monophyly of the northern specimens was also recovered in some analyses. Faced with the absence of resolution in our molecular analyses, we took a conservative decision, considering M. species ‘D’ under M. touan as a geographical variant of the latter, instead of describing it as a new species.

Figures

Figure 2. Phylogenetic relationships of species of the Monodelphis brevicaudata complex represented by the Bayesian tree resulting from the analysis of the combined matrices of 471 base pairs of the mitochondrial cytochrome b gene and 402 base pairs of the mitochondrial 16S rDNA gene. Numbers above branches represent parsimony followed by maximum-likelihood bootstrap; numbers below branches correspond to Bayesian posterior probabilities (‘-’ means a value lower than 50%). Asterisks refer to specimens/localities not examined morphologically.

Figure 4. Dorsal (left) and ventral (right) views of the skins of adult specimens of (top to bottom): Monodelphis glirina (USNM 521429), Monodelphis palliolata (USNM 406904), Monodelphis brevicaudata (USNM 385005), Monodelphis arlindoi sp. nov. (UFMG 3190, paratype), Monodelphis touan (IEPA 1154). Scale bar = 50 mm.

Figure 5. Dorsal (top) and ventral (bottom) views of the skulls of old adult specimens of: A, Monodelphis glirina (USNM 521431, female); B, Monodelphis palliolata (USNM 371285, female); C, Monodelphis brevicaudata (USNM 385005, female); D, Monodelphis arlindoi sp. nov. (MPEG 38052, holotype, male); E, Monodelphis touan (ISEM V-1563, male). Scale bar = 10 mm.

Figure 6. Distribution of species of the Monodelphis brevicaudata complex recognized in this study. Species boundaries (shades) are based on our data and Pine & Handley (2008). Points indicate collecting localities of specimens examined by us (except for species B, not analysed). Monodelphis palliolata also occurs in Colombia, but distribution in that country cannot be correctly drawn because of the absence of known precise localities (Pine & Handley, 2008).