Pseudalopex

Lyras, George A. & Van Der Geer, Alexandra A. E., 2003, External brain anatomy in relation to the phylogeny of Caninae (Carnivora: Canidae), Zoological Journal of the Linnean Society 138 (4), pp. 505-522 : 518-519

PSEUDALOPEX

There has been a general disagreement on the classification of the South American Caninae species Dusicyon australis (Falkand Island wolf), Pseudalopex vetulus (hoary fox) and the zorros Pseudalopex culpaeus (culpeo fox), P. griseus ( Argentine grey fox), P. gymnocercus (pampas fox) and P. sechurae (sechuran fox). Earlier works ( Thomas, 1914; Kraglievich, 1930; Cabrera, 1931; Osgood, 1934) each presented a different taxonomy of these species.

Langguth (1969, 1970) placed the hoary fox in the genus Lycalopex and the other species into the genus Dusicyon , giving them only subgeneric recognition. Later (1975) he moved these latter species to the genus Canis , as according to him they did not differ enough to grant a full generic rank. Clutton-Brock et al. (1976) noted that there were close similarities between the six species, and accordingly grouped them into the genus Dusicyon . Berta (1987, 1988), however, suggested that † Dusicyon australis should be separated from the others, and placed under the generic name Pseudalopex the species Pseudalopex culpaeus , P. griseus , P. sechurae and P. gymnocercus . She also moved the genus Lycalopex into Pseudalopex ; this was, however, a taxonomic mistake as the generic name Lycalopex has priority above Pseudalopex ( Zunino et al., 1995) . Tedford et al. (1995) kept the genus Lycalopex (for L. vetulus ) and considered the Pseudalopex group (sensu Berta, 1988) as paraphyletic. Within the genus Pseudalopex they placed only the culpeo fox ( P. culpaeus ), while the three remaining species were indicated by quotation marks, since there was no proper generic name: ‘ Pseudalopex ’ gymnocercus , ‘ P. ’ sechurae and ‘ P. ’ griseus . Wayne & O’Brien (1987), based upon allozymes, placed P. vetulus with Cerdocyon ; later, Wayne et al.’s (1997) analysis resulted in a dichotomy with P. culpaeus and P. vetulus on one side and P. sechurae on the other.

The brain morphology of the above mentioned South American species (including † Dusicyon australis ) indicates that they are not directly related to the genus Canis . The patterns of the external cerebrum anatomy of culpaeus , griseus , sechurae , gymnocercus and vetulus are very similar ( Fig. 8 ). Only P. culpaeus deviates, whose coronal sulci forms a heartshaped outline on the dorsal cortex, whereas in P. vetulus , P. griseus , P. gymnocercus , P. sechurae , and mitochondrial DNA, to Speothos alone ( Wayne et al., 1997).

Features of the external brain anatomy of Chrysocyon separated this genus from Canis , and support its classification within the South American Caninae . Its sulcal pattern, especially at the cortex medial to the coronal sulci, differs completely from that found in the Canis species. In the latter genus it is always orthogonal or oblong ( Fig. 5), whereas in Chrysocyon it is more oval, parenthesis-like, and with a very welldeveloped posterior part of the sigmoid gyrus ( Fig. 7 ). The parenthesis-like sulcal pattern is also found in Pseudalopex , † Dusicyon and Cerdocyon ( Fig. 8 ), but these last three genera all lack the typical expansion of the posterior part of the sigmoid gyrus. The remaining South American canids, Atelocynus and Speothos , have an orthogonal sulcal pattern ( Fig. 7 ) which is more or less similar to Canis . Chrysocyon should be placed with Pseudalopex , † Dusicyon and Cerdocyon , but we are not able to say where exactly.

they form a parenthesis-like or oval outline ( Fig. 8 ). This is the only difference seen in the anterior part of the brain that might support a separate generic status of P. culpaeus . There are no features of the brain morphology that distinguish P. vetulus from the others, so a separate generic status of the former cannot be defended from the point of view of anterior brain morphology.

Figures

Figure 7. Endocasts from Chrysocyon, Speothos, Atelocynus and the recently extinct †Dusicyon australis, dorsal and lateral views.

Figure 8. Endocasts from Pseudalopex spp. and Cerdocyon thous, dorsal and lateral views.