Microcavia australis (I. Geoffroy and d'Orbigny, 1833)

Teta, Pablo, Ojeda, Ricardo A., Lucero, Sergio O. & D’Elía, Guillermo, 2017, Zavreliella shidai Han & Liu & Luo & Tang 2021, sp. n., Zoological Studies 56 (29), pp. 1-18 : 9-11

Microcavia australis (I. Geoffroy and d’Orbigny,

1833)

( Figs. 3-6 )

C [avia]. australis I. Geoffroy and d’Orbigny, 1833:1 .

Kerodon Kingii Bennett, 1836:190 [type locality “apud Portum Desire dictum, ad Patagoniae littus orientale” (= Puerto Deseado, Santa Cruz, Argentina)].

Caviella australis nigriana Thomas, 1921:446 [type locality “ Neuquen, R. Negro” (= Neuquén, Argentina).

Type locality: “sur les bords du Rio Negro, vers le Quarante- unième degré,” restricted to “on the Lower Rio Negro,” Río Negro, Argentina ( Thomas 1929:44).

Emended morphological diagnosis: A medium-size species of Microcavia (length of head and body ca. 188 mm, condylo-incisive length ca. 40 mm) characterized by the following combinations of characters: dorsal coloration brownish to olive brown, with gray to yellowish gray underparts; skull strongly built, wide and relatively short; dorsal profile bowed to strongly bowed; nasals narrow anteriorlyt; zygomatic arches widely expanded and rounded; inferior process of the jugal posteriorly extended to the level of the posterior border of the glenoid fossa; suture between palatines occupied by a triangular to more or less heart-shaped palatal crista; rounded to acute posterior palatal edges, large sphenopalatine vacuities and relatively narrow presphenoids; incisors orthodont to proodont and usually visible from above.

Distribution: M. australis is found in Argentina from highland areas (> 2000 m a.s.l.) of Mendoza province in the west and southern Buenos Aires province in the east, south to Santa Cruz province and adjoining parts of southern Chile ( Dunnum 2015; Udrizar Sauthier et al. 2016). Populations from high mountain areas of San Juan Province could also correspond to M. australis , at least judging by their small size and skull morphology (q.v., Taraborelli et al. 2007).

Taxonomic remarks: No trend in size or morphologic variation was detected throughout the extensive distribution of M. australis s.s. We found not evidence indicating that southern Patagonian populations are different, as has been suggested by the taxonomic scheme of Thomas (1921); therefore, no subspecies are recognized.

Figures

Fig. 3. Dorsal (A-C) and ventral (D-F) views of the skull of three species of Microcavia: M. australis (A, D; MACN-Ma 14.543), M. maenas (B, E; MACN-Ma 34.116) and Microcavia n. sp. (C, F; MACN-Ma 17333). Scale bars = 5 mm.

Fig. 4. Lateral views of the skull and right dentaries in labial views of three species of Microcavia: M. australis (A; MACN-Ma 14.543), M. maenas (B; MACN-Ma 34.116) and Microcavia n. sp. (C; MACN-Ma 17331). Scale bars = 5 mm.

Fig. 5. Selected anatomical traits of three species of Microcavia (A, MACN-Ma 16379; B, MACN-Ma 34.81; C, MACN-Ma 17331; D, MACN-Ma 16379; E, MACN-Ma 36.72; F, MACN-Ma 17333; G, MACN-Ma 28.51; H, MACN-Ma 36.84; I, MACN-Ma 17331), depicting the relative position of inferior process of the jugal (marked by the arrow) relative to the glenoid cavity (a-c) and size and shape of the palatal cristae (d-i). A, D, G = M. australis; B, E, H = M. maenas; C, F, I = M. n. sp. Abbreviations: gc = glenoid cavity; jf = jugal fossa; mpp = medial process of the palate; pc = palatal crista; sq = squamosal. Photographs are not in scale to facilitate comparisons among proportions.

Fig. 6. Selected anatomical traits of three species of Microcavia (A, MACN-Ma 14543; B, MACN-Ma 36.72; C, MACN-Ma 17331; D, MACN-Ma 25.51; E, MACN-Ma 36.84; F MACN-Ma 17333), depicting the contour of the posterior border of the palate and size of sphenopalatine vacuities (epv). Abbreviations: fo = foramen oval; pc = palatal crista; ps = presphenoid; pt = pterygoid. Photographs are not in scale to facilitate comparisons among proportions.