Microcavia maenas ( Thomas, 1898 )

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 : 11-12

Microcavia maenas ( Thomas, 1898)

( Figs. 3-6 )

Cavia maenas Thomas, 1898:284 .

Caviella australis salinia Thomas, 1921:447 [type locality “Recreo,” Catamarca, Argentina].

Caviella australis joannia Thomas, 1921:446 [type locality “ Cañada Honda, San Juan. Alt. 500 m,” Argentina].

Type locality: “Chilecito, Rioja, 1200 metres,” La Rioja, Argentina ( Thomas 1898).

Emended morphological diagnosis: A largesize species of Microcavia (length of head and body ca. 203 mm, condylo-incisive length ca. 44 mm) having the following combinations of characters: dorsal coloration yellowish gray in some samples (e.g., cata, lari) to brownish in others (e.g., sjun), underparts grayish to yellowish; skull strongly built, wide and larger than in australis and the new species described below; dorsal profile of the skull slightly bowed; outer margins of nasals almost parallel-sided; zygomatic arches widely expanded and rounded; jugals posteriorly extended behind the border of the glenoid fossa; long and narrow to long and slightly rhomboidal palatal crista along the suture between palatine bones; usually angled to rounded posterior palatal edge, sometimes with a caudal nasal spine; sphenopalatine vacuities small; presphenoids broad; incisors nearly orthodont and not visible from above.

Distribution: The distribution of M. maenas extends up to 2,500 m along montane and hilly areas of Catamarca, La Rioja, Salta, San Juan and Tucumán provinces, and arid lowlands of western Córdoba, north-central Mendoza and northern San Luis provinces. Cabrera (1953) referred an individual trapped in Yavi Chico, Jujuy (MACN- Ma 36.426) to M. a. maenas , but our inspection of this specimen led us to re-identify it as Galea comes . Microcavia australis and M. maenas are both present in Mendoza province, although their distributions appears to be allopatric; whereas M. australis is restricted to localities at middle and high altitude (> 2000 m a.s.l.), M. maenas is found in the lowland terrains east of los Andes (<1500 m a.s.l.). The distributional ranges of both forms are rather uncertain diffuse and further studies are needed to clarify the limits between them.

Taxonomic remarks: The taxonomic arrangement proposed here, in which salinia is recognized as synonym of maenas , was suggested earlier by Thomas (1921) who wrote “No doubt [salinia is] nearly allied to C. a. maenas …”. Qualitative and quantitative traits suggest that samples from cata, cord, lari, menc, menl, sjun sjus, salu, salt, and tucu belong to a single lineage for which the oldest available name is maenas . Samples from sjus, nearl topotypes of joannia, do not differ in size or morphology from other samples referred to maenas . Specimens from Salta (salt), were not include in the quantitative analyses because the entire sample was composed by broken skulls; however, the available measurements are close to those of other northwestern samples, warranting its inclusion in maenas .

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.