Oecomys mamorae (Thomas)

Carleton, Michael D., Emmons, Louise H. & Musser, Guy G., 2009, A New Species of the Rodent Genus Oecomys (Cricetidae: Sigmodontinae: Oryzomyini) from Eastern Bolivia, with Emended Definitions of O. concolor (Wagner) and O. mamorae (Thomas), American Museum Novitates 3661, pp. 1-32: 25-26

publication ID

http://doi.org/ 10.1206/612.1

persistent identifier

http://treatment.plazi.org/id/B603DD14-6D70-FF9F-01DE-8AA2FDC9A393

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Felipe

scientific name

Oecomys mamorae (Thomas)
status

 

Oecomys mamorae (Thomas)  

Oryzomys (Oecomys) mamorae Thomas, 1906b: 445   (type locality— Bolivia, Cochabamba, Yungas, upper Río Mamore´, Mosetenes ; holotype —BMNH 1900.8.3.21).

Oecomys mamorae: Osgood, 1916: 206   (name combination).

Oryzomys mamorae: Ellerman, 1941: 358   (name combination).

Oryzomys mamorae mamorae: Cabrera, 1961: 405   (retained as species, ranked as nominate subspecies).

Oryzomys concolor roberti: Hershkovitz, 1960: 559   (part, mamorae   allocated as full subspecific synonym).

Oecomys concolor roberti: Anderson, 1985: 12   (part, marmorae listed as full synonym).

EMENDED DIAGNOSIS: A species of Oecomys   ( Sigmodontinae   : Oryzomyini   ) characterized by a combination of medium-large size (HBL <130–150 mm, HFL <25–29 mm, ONL <31–33 mm), relatively long tail (TL <150–170 mm), narrow interorbit and weakly developed supraorbital ridges, long and narrow incisive foramina, relatively short bony palate and simple posterolateral palatal pits, alisphenoid struts typically absent, and a derived carotid circulatory pattern (skull lacking squamosal-alisphenoid groove, sphenofrontal foramen, and posterolateral groove on the parapterygoid plate; posterior opening to the alisphenoid canal compressed; stapedial foramen absent; groove dorsally crossing the parapterygoid plate present).

DISTRIBUTION: Subhumid and gallery forests in savanna and Chaco zones of central and eastern Bolivia, contiguous westcentral Brazil, and northern and eastern Paraguay (fig. 6). Known elevational range sea level to 2100 m   , most localities within 200–500 m.

REMARKS: The cranium of the type specimen of mamorae   (BMNH 1900.8.3.21), an old adult female, exhibits the essential traits of a derived carotid pattern (no sphenofrontal foramen, stapedial foramen minute), yet it does retain shallow traces of the squamosalalisphenoid groove on the inner walls of the braincase. As in most specimens of O. mamorae   that we have examined (table 5), the type lacks alisphenoid struts. Thomas (1906b: 446) critically contrasted his new form O. mamorae   to marmosurus   , here allocated as a junior synonym of O. concolor   , and captured the consistent proportional differences that we have observed in the larger samples of each species now available: ‘‘the distinction of this animal [ O. mamorae   ], which may be separated from its only equal in size, O. (Oe.) marmosurus   , by its narrower interorbital region, less developed orbital ledges, and larger palatal foramina.’’ The interorbital constriction (IOB) and long incisive foramina (LIF) correlate strongly with the first canonical variate that discriminates specimens of O. mamorae   from those of O. concolor   and O. sydandersoni   (fig. 3; tables 3, 4, 7).

Following Thomas, O. mamorae   had been retained as a distinctive species by most authors until Hershkovitz (1960) submerged it within his expansive view of O. concolor   , as a full synonym of O. c. roberti   . Hershkovitz’s definition of the subspecies confused two distinctive species, O. roberti Thomas (1903)   and O. mamorae Thomas (1906b)   , which are easily separable from one another and from O. concolor (Wagner)   proper. Examples of O. roberti   , like most other Oecomys   , retain the complete carotid arterial pattern in contrast to the derived condition found in O. mamorae   . Although the dorsal pelage of both species tends to be pale ochraceous-tawny and the venter mostly white, the cover hairs are typically shorter in O. roberti   (3–5 mm over the rump) than O. mamorae   (7–9 mm). In addition, the supraorbital shelf and posterolateral palatal pits are more pronounced in O. roberti   . Specimens of O. roberti   have been recorded in northern and easternmost Bolivia ( Anderson, 1997; Emmons et al., 2006), just peripheral to the range of O. mamorae   (fig. 6), but the two species have yet to be discovered in sympatry.

Specimens of Oecomys   have been recovered from owl pellets in northeastern Argentina, from the provinces of Chaco ( Massoia and Fornes, 1965, as O. concolor   ) and Formosa ( Pardiñas and Ramírez-Llorens, 2005, as O. sp.). By geographic proximity alone, these samples are plausibly referable to O. mamorae   , but certain measurements reported for the fragmented crania of the Argentine form seem to run larger than O. mamorae   proper from Bolivia (notably IOB, LIF, BIF, LD, WM1— Pardiñas and Ramírez-Llorens, 2005: table 1). Critical review of variation within nominal O. mamorae   and comparisons with the Argentine populations are required to verify their specific assignment. Such a review should include those populations documented in eastern Paraguay, to the east of the Paraguay River, reported as O. concolor ( Myers, 1982)   and here referred to O. mamorae   based on our examinations.

SPECIMENS EXAMINED: 128, as follows. Bolivia — Beni, Baures ( FMNH 117063–117066 View Materials )   ; Boca del Río Ibaré ( AMNH 211749 View Materials )   ; Río Ibare´ , 26 km from mouth ( AMNH 211718 View Materials , 211719 View Materials , 211750–211752 View Materials )   ; Busurucucú, Yacuma Prov. , 200 m ( AMNH 263491 View Materials )   ; Lúcuma , 6 leagues S San Ramón ( USNM 460430 View Materials )   ; Magdalena ( FMNH 117055–117058 View Materials )   ; Río Beni, El Consuelo, 196 m ( NHMS 153)   ; Río Beni, Puerto Salinas, 226 m (NHMS 62–64, 74–77, 79, 80); Mamoré River ( AMNH 211753 View Materials )   ; Río Mamore´, Marbán , 240 m ( AMNH 129254 View Materials , 129255 View Materials )   ; Mamore´, San Joaquín ( FMNH 117053 View Materials , 117059 View Materials , 117067 View Materials , 117068 View Materials ; USNM 391302 View Materials )   ; Río Tijamuchi , sea level ( AMNH 262012 View Materials )   ; Yuatre ( FMNH 117060 View Materials , 117061 View Materials )   ; Km 35, NW of Yucumo, 253 m ( AMNH 264769 View Materials ; MSB 68481 View Materials )   . Chuquisaca, 2 km E Chuhuayacu , 1200 m ( MSB 63355 View Materials )   ; Tomina Province, 40 km from Padilla, Tola Orko , 2100 m ( USNM 271581 View Materials , 271582 View Materials , 271584– 271587 View Materials )   ; Río Limón , 1300 m ( MSB 63354 View Materials )   ; Tomina Province , Tihumayu ( USNM 290906 View Materials )   ; Ticucha, Río Capirenda ( FMNH 72890 View Materials )   . Cochabamba, Boca Río Chapare , 825 ft ( ANSP 19405 View Materials )   ; Río Moile Ichilo (Inst. Roy. Sc. Nat. Belgium 20103, 25297); Todos Santos , 1300 ft ( AMNH 38520–38523 View Materials , 38561 View Materials , 38563–38566 View Materials , 38568–38578 View Materials , 40782–40786 View Materials ; FMNH 21520–21524 View Materials )   ; Yungas Prov., upper Río Mamore´ , Mission Mosetenes ( BMNH 1900.8.3.21 [holotype of mamorae   ], 1900.8.3.24)   . La Paz, 1 mi W Puerto Linares ( MSU 33018 View Materials )   . Santa Cruz, Andrés Ibáñez Prov. , Ayacucho ( USNM 390655 View Materials )   ; Cordillera Prov. , Basilio ( USNM 390654 View Materials )   ; Buena Vista , 350, 450, and 500 m ( AMNH 61776 View Materials ; BMNH 26.12.4.52, 28.2.9.39–28.2.9.42, 51.5.23.6; FMNH 25267, 25268, 51907, 51913, 51915)   ; Cordillera Province, 5 km S Choreti, Camiri , 1000 m ( CAS 13805 View Materials ; USNM 276602 View Materials )   ; 3.5 km W Estación Pailón , 300 m ( AMNH 260420 View Materials ; MSB 55313 View Materials )   ; 3 km N and 7 km E Ingeniero Mora , 490–580 m ( AMNH 247757 View Materials )   ; Punta Rieles ( AMNH 263101–263104 View Materials , 263366 View Materials )   ; San Rafael de Amboró , 400 m ( AMNH 262013 View Materials , 262014 View Materials , 262119 View Materials , 262099 View Materials ; MSB 56072 View Materials )   ; Velasco Prov. , Santa Ana ( USNM 390656 View Materials , 391301 View Materials )   ; 15 km S Santa Cruz, 400 m ( MSB 58648 View Materials )   ; Santa Cruz de la Sierra, 410 m ( CM 2146, 2749)   ; Río Yapacaní ( FMNH 51914 View Materials )   . Brazil — Mato Grosso, Caiçara ( NMW B475 View Materials )   ; Descalvados, Uca ( FMNH 26643 View Materials )   . Mato Grosso do Sul, Fazenda Acurizal ( USNM 531278 View Materials )   ; Río Paraguai, Urúcum de Corumbá ( FMNH 26811 View Materials )   . Paraguay — Amambay, Bella Vista, Colonia Sargento Dure´ , 3 km (by road) E Río Apa ( MSB 70699 View Materials , 70739 View Materials )   . Chaco, 50 km WNW Fortín Madrejón, Cerro León ( UMMZ 125456 View Materials )   ; 28 km WNW Mayor Pablo La Gorenza, edge Río La Gorenza (5 Río Timane), San Alfredo ( UCONN 19187–19189 View Materials )   . Misiones, 40 km S San Ignacio ( AMNH 234787 View Materials )   . Paraguari, 17 km SW Piribebuy, Saltos de Pirareta ( UMMZ 133793 View Materials )   .

MSB

Museum of Southwestern Biology

MSU

Michigan State University Museum

CAS

California Academy of Sciences

NMW

Naturhistorisches Museum, Wien

Kingdom

Animalia

Phylum

Chordata

Class

Mammalia

Order

Rodentia

Family

Muridae

Genus

Oecomys

Loc

Oecomys mamorae (Thomas)

Carleton, Michael D., Emmons, Louise H. & Musser, Guy G. 2009
2009
Loc

Oecomys concolor roberti:

Anderson, S. 1985: 12
1985
Loc

Oryzomys mamorae mamorae:

Cabrera, A. 1961: 405
1961
Loc

Oryzomys concolor roberti:

Hershkovitz, P. 1960: 559
1960
Loc

Oryzomys mamorae: Ellerman, 1941: 358

Ellerman, J. R. 1941: 358
1941
Loc

Oecomys mamorae:

Osgood, W. H. 1916: 206
1916
Loc

Oryzomys (Oecomys) mamorae

Thomas, O. 1906: 445
1906