Thylamys venustus ( Thomas, 1902 )

Giarla, T. C., Voss, R. S. & Jansa, S. A., 2010, Species Limits And Phylogenetic Relationships In The Didelphid Marsupial Genus Thylamys Based On Mitochondrial Dna Sequences And Morphology, Bulletin of the American Museum of Natural History 2010 (346), pp. 1-67 : 56-58

Thylamys venustus ( Thomas, 1902)

SYNONYMS: cinderella Thomas, 1902 .

DISTRIBUTION: Based on specimens that we sequenced, Thylamys venustus occurs along the eastern slopes and foothills of the Andes from Bolivia (Cochabamba, Chuquisaca, Santa Cruz, and Tarija) to northwestern Argentina (Jujuy and Tucumán; fig. 9) with recorded elevations ranging from about 350 to 4000 m above sea level. Although we have not investigated every published extralimital record of this species, those from Lima, Peru ( Tate, 1933) and Oruro, Bolivia ( Anderson, 1997) appear to be based on misidentified material (see Remarks). Gardner’s (2005) record from Neuquén, Argentina, was based on an editing error (A.L. Gardner, in litt., 23 February 2010).

The known geographic range of Thylamys venustus overlaps those of T. pallidior , T. pusillus , and T. sponsorius ; known cases of sympatry among these species have already been described in preceding accounts.

MORPHOLOGICAL DIAGNOSIS: Body pelage tricolored (abrupt line of transition from darker middorsal to paler dorsolateral coloration present); ventral pelage gray-based yellowish or whitish; plantar pads of manus separate, surrounding a convex central palmar surface; manual claws short, not extending much if at all beyond fleshy apical pads of digits; tail substantially longer than the combined length of head and body (LT/ HBL X 100 5 131%; N 5 21), without pale tip; prehensile ventral surface of tail tip well developed. Nasal bones usually extending posteriorly as far as or behind lacrimals; lacrimal foramina variable in position (no unambiguously modal condition observed among sequenced specimens); infraorbital foramen usually above P3 or above P3/M1 commissure; nasolabial fossa shallow; supra- orbital margins usually rounded or squared, sometimes produced as small postorbital processes; maxillary fenestrae almost always present bilaterally; crown of second upper incisor (I2) consistently smaller than or subequal to crown of I3; stylar cusp C variably present or absent on M1 and M2, but seldom a discrete, well-developed structure (usually partially fused with stylar cusp D); metaconule usually absent on M3.

COMPARISONS: See the preceding species account for morphological comparisons between Thylamys venustus and T. sponsorius .

REMARKS: Diligent visual and morphometric comparisons of voucher material has not allowed us to discover any phenotypic attribute that distinguishes the three allopatric haplogroups of Thylamys venustus designated A, B, and C in figures 8 and 10. The skins, skulls, and dentitions assignable to those groups are qualitatively similar and overlap broadly in all recorded measurements. In effect, they appear to represent a single morphological species. Despite the apparent absence of diagnostic morphological traits, however, available names can tentatively be assigned to two of them based on geographic criteria: the type locality of venustus (in the Bolivian department of Cochabamba; table 14) falls within the known range of the haplogroup A, whereas the type locality of cinderella (in the Argentinian province of Tucumán) falls within the known range of haplogroup C. Apparently, no name is currently available for haplogroup B.

We examined one of the two specimens that Tate (1933: 225) identified as Marmosa venusta from the Peruvian department of Lima, on the wrong (western) side of the Andes and over 1000 km from the nearest collection locality of any material conforming to T. venustus as recognized herein. The specimen in question (FMNH 24141), a juvenile male skin and skull collected in 1922 by J.T. Zimmer at Matucana (11 ° 51 9 S, 76 ° 24 9 W, 2378 m; Stephens and Traylor, 1983), has a relatively short tail (108% of HBL), long claws, and a narrow but continuous median streak of self-white ventral fur flanked by broad lateral zones of gray-based hairs, traits that better match the characteristics we associate with the Elegans Group than those we associate with the Venustus Group (table 16). Solari (2003) examined this specimen and identified it as T. pallidior , but we believe it to represent one of the unnamed phenotypes related to T. tatei , as discussed above in the account for the latter species.

Three specimens from the Bolivian department of Oruro that Anderson (1997) identified as Thylamys venustus are the only examples reported from the altiplano, where only T. pallidior is known to occur. Although Anderson did not publish the museum catalog numbers of the material he examined, his card files (in the AMNH Department of Mammalogy archives) identify the Oruro specimens as CM 5227, MVZ 119912, and USNM 121157. We have not been able to examine all of these, but CM 5227 (currently identified in the Carnegie Museum database as ‘‘ T. elegans ’’) was collected by José Steinbach in Cochabamba (not Oruro; S. McClaren in litt., 26 January 2010), and USNM 121157 (which we did examine) is unambiguously identifiable as T. pallidior . The current identification of MVZ 119912 in the database of the Museum of Vertebrate Zoology (Berkeley) is T. pallidior , in agreement with what we would have supposed based on its geographic origin.

SPECIMENS EXAMINED (N 5 43): Argentina — Jujuy, Highway 9 at border with Salta ( OMNH 29952 ), Santa Bárbara ( AMNH 185323 ), Yuto ( AMNH 186948 ) ; Tucumán, 12 km WNW Burruyacú along Río Cajón ( OMNH 29966 ), Los Chorillos ( OMNH 29976 ). Bolivia — Chuquisaca, 3.8 km by road E Carandaytí ( AMNH 261245 ), 2 km SW Monteagudo ( MSB 63261, 63262 ), 9 km by road N Padilla ( MSB 63267, 63268 ), 11 km N and 16 km W Padilla ( AMNH 263558 , MSB 63269), Porvenir ( AMNH 261254 , 261255 , 261260 ; MSB 55837), 1.3 km SW Porvenir ( AMNH 261264 ), Río Limón ( MSB 63264), 2 km N Tarabuco ( AMNH 263556 ), 4 km N Tarabuco ( AMNH 263555 ), 12 km N and 11 km E Tarabuco ( MSB 63265, 63272 , 63273 ) ; Cochabamba, 1.3 km W Jamachuma ( AMNH 275427 ), Parotani ( BMNH 2.1.1.118–2.1.1.121 [type series of venustus ]), 7.5 km SE Rodeo ( AMNH 275429 , MSB 87100, 87109 ), Tholapujru ( AMNH [uncataloged]), 17 km E Totora ( AMNH 275428 , MSB 67001) ; La Paz, Caracato ( AMNH

TABLE 25

Documented Cases of Sympatry Among Species of Thylamys

Locality Sympatric species a

Argentina: Jujuy, 9 km NW Barcena b T. pallidior (OMNH 29963) and T. sponsorius (OMNH 29974)

Argentina: Mendoza, ‘‘Nacunan Reserve’’ c T. pusillus (UWBM 72205) and T. pallidior (UWBM 72195)

Bolivia: Chuquisaca, 3.8 km E Carandaytí b T. pusillus (AMNH 261268, MSB 55846) and T. venustus (AMNH 261245)

Bolivia: Tarija, 3 km SE Cuyambuyo b T. sponsorius (AMNH 275448–275450, MSB 67014) and T. venustus (AMNH 275436, 275447; NK 23762d)

Bolivia: Tarija, 8 km S & 10 km E Villa Montes T. pusillus (AMNH 246442–246450) and T. venustus (AMNH 246451)

a

Museum catalog

number(s) of exemplar specimen(s) in parentheses.

b See gazetteer (appendix 1) for geographic coordinates.

c Reserva Biósfera de Ñacuñán (ca. 34 ° S, 68 ° W).

d Tissue number (voucher not seen).

e Villa Montes is at 21 ° 15 9 S, 63 ° 30 9 W.

248704, 248705); Santa Cruz, Cerro Itahuaticua (MSB 63260), 5 km by road SE Comarapa (AMNH 260030), 15 km NE Quiñe (MSB 87106), 6 km NNE Quiñe (MSB 87107), 17 km S Quiñe (MSB 67003), Río Ariruma (AMNH 275433), 5.5 km by road NE Vallegrande (MSB 67005), 5.5 km by road NNW Vallegrande (MSB 67004); Tarija, 1 km S Camatindy (MSB 67007), 3 km WNW Carapari (MSB 67392), Tapecua (MSB 67008).