Cryptonanus chacoensis ( Tate, 1931 )

VOSS, ROBERT S., LUNDE, DARRIN P. & JANSA, SHARON A., 2005, On the Contents of Gracilinanus Gardner and Creighton, 1989, with the Description of a Previously Unrecognized Clade of Small Didelphid Marsupials, American Museum Novitates 3482, pp. 1-35 : 14-15

Cryptonanus chacoensis ( Tate, 1931)

Marmosa agilis chacoensis Tate, 1931: 10 . Original description based on the holotype (by original designation: BMNH 4.1.5.48) collected at Sapucay , Paraguay, and five paratypes.

Marmosa (Thylamys) agilis agilis: Cabrera, 1958: 27 (part). New name combination and synonymy based on alleged identity with the nominotypical form of M. (T.) agilis (Burmeister, 1854) .

Gracilinanus agilis: Gardner and Creighton, 1989: 5 (part). New name combination.

IDENTIFICATION AND DISTRIBUTION: We are using this name for specimens of Cryptonanus with self­colored ventral fur (versus ventral fur gray­based in C. guahybae ), 4– 1–4 5 9 abdominal­inguinal mammae (versus 7–1–7 5 15 mammae, of which the anteriormost two or three pairs are pectoral in C. guahybae ), small molars (LM 5 4.9–5.4 mm, versus mostly. 5.4 mm in C. unduaviensis ), and an incomplete anterior cingulum on M3 (versus M3 anterior cingulum narrow but complete in other forms). Specimens that we examined with these traits are from Paraguay and northern Argentina (Chaco and Jujuy). If correctly identified, the specimens reported by Massoia and Fornes (1972) also document the occurrence of this species in the Argentinian provinces of Buenos Aires, Entre Ríos, Formosa, and Misiones. 7 External and craniodental measurements of representative specimens examined are provided in table 6.

REMARKS: Tate (1933) reported BMNH specimens of both Marmosa agilis agilis and M. a. chacoensis from Sapucay, Paraguay, but he did not appear to recognize the paradox of sympatric subspecies at this locality, nor did he provide any unambiguous morphological criterion for distinguishing them. Cabrera (1958) thought that two such doubtfully distinct taxa were unlikely to occur together and synonymized them under the former trinomen, apparently without having examined the material in question. In fact, the BMNH specimens from Sapucay were correctly identified by Tate and exhibit all of the diagnostic features of the genera to which we now refer them. Although taken at the same locality, the Sapucay specimens of Gracilinanus agilis and Cryptonanus chacoensis were not collected simultaneously, and it is

7 Massoia and Fornes (1972) did not describe any of the diagnostic traits of Cryptonanus , but their cranial illustration seems to indicate that maxillary vacuities and a secondary foramen ovale are absent, and their cranial measurements (e.g., zygomatic breath and least interorbital breadth) broadly overlap our measurements of C. chacoensis . On the other hand, the illustrated dentition lacks accessory canine cusps (usually present in C. chacoensis ), and P2 seems to be subequal in height to P3. Because their report provides unique information about the distribution and natural history of C. chacoensis in northeastern Argentina, the specimens they collected should be reexamined to confirm this identification.

possible that they were found in different local habitats. 8

Anderson (1997) reported four specimens of ‘‘ Gracilinanus agilis chacoensis ’’ from three Bolivian localities. Based on a card file in the AMNH Department of Mammalogy archives that provides the museum catalog numbers of the specimens Anderson examined, we determined that his record of chacoensis from Chuquisaca was based on MSB 63275, an unidentified species of Marmosops (see Voss et al., 2004b). Unfortunately, we have not been able to examine the other material that Anderson reported as chacoensis , most of which was returned to Bolivia.

SPECIMENS EXAMINED: Argentina — Chaco, Las Palmas ( USNM 236329 ) ; Jujuy, Santa Barbara ( AMNH 185270 ) , Yuto ( AMNH 167851 ) . Paraguay — Alto Paraguay, Estancia Doña Julia (TK 61053, 61072, 61074, 61103); Caazapá, Estancia Dos Marias ( GD 521 ) ; Canendiyú , 13.3 km N Curuguaty by road ( UMMZ 137143 ) ; Chaco, Palmar de las Islas (TK 65331); Concepción, Concepción ( BMNH 11.11.19.23), Río Aquidaban at Paso Horqueta ( UMMZ 134552 ) ; Cordillera, 1.6 km by road S Tobatí ( UMMZ 126105 ) ; Paraguarí, Sapucay ( BMNH 4.1 .5.48, 5.8.1.8); Presidente Hayes, Estancia La Victoria (TK 60201) .