Marmosa robinsoni Bangs, 1898

Part, Tate’, The Species In, Mexicana’, And, Closely, Mitis’ Sections And Other & Forms, Related, 2010, A Revision Of The Didelphid Marsupial Genus Marmosa, Bulletin of the American Museum of Natural History 2010 (334), pp. 1-83 : 48-58

Marmosa robinsoni Bangs, 1898 Figures 23, 24

? Didelphys murina: Alston, 1880: 200 . Part, not Didelphis murina Linnaeus, 1758 .

Didelphis (Micoureus) murina: Allen and Chapman, 1893: 230 . Name combination.

Marmosa murina: Thomas, 1896: 314 . Name combination.

Marmosa murina: Allen and Chapman, 1897: 27 .

Marmosa robinsoni Bangs, 1898a: 95 . Type locality ‘‘Margarita Island, Venezuela.’’

Marmosa mitis Bangs, 1898b: 162 . Type locality ‘‘Pueblo Viejo, Colombia, 8000 ft. ’’

Marmosa chapmani Allen, 1900: 197 . Type locality ‘‘Caura, Trinidad.’’

Marmosa fulviventer Bangs, 1901: 632 . Type locality ‘‘San Miguel Island[, Panama].’’

Marmosa mitis: Allen, 1904a: 337 .

Marmosa mitis: Allen, 1904b: 417 .

[ Marmosa ] fulviventer: Elliot, 1904: 5 .

Marmosa fulviventer: Elliot, 1905: 3 .

Marmosa grenadae Thomas, 1911: 514 . Type locality ‘‘Annandale[, Island of Grenada, West Indies].’’

Marmosa nesaea Thomas, 1911: 515 . Type locality ‘‘Caparo[, Trinidad].’’

Marmosa mitis casta Thomas, 1911: 516 . Type locality ‘‘San Esteban, Carabobo, N. Venezuela.’’

Marmosa chapmani: Allen, 1911a: 194 .

Marmosa mitis costa: Allen, 1911b: 245. Incorrect subsequent spelling of Marmosa mitis casta Thomas, 1911 .

Marmosa mitis casta: Allen, 1911b: 246 .

Marmosa mitis pallidiventris Osgood, 1912: 39 . Type locality ‘‘El Guayabal, 10 miles N. of Cucuta, Colombia.’’

[ Marmosa ] mitis: Cabrera, 1913: 12 .

[ Didelphis (Marmosa) ] fulviventer: Matschie, 1916: 270 . Name combination.

[ Didelphis (Marmosa) ] chapmanni: Matschie, 1916: 270. Incorrect subsequent spelling of Marmosa chapmani Allen, 1900 ; name combination.

[ Didelphis (Marmosa) ] grenadae: Matschie, 1916: 270 . Name combination.

[ Didelphis (Marmosa) ] robinsoni: Matschie, 1916: 270 . Name combination.

[ Didelphis (Marmosa) ] casta: Matschie, 1916: 270. Name combination.

[ Didelphis (Marmosa) ] pallidiventris: Matschie, 1916: 270. Name combination.

[ Didelphis (Marmosa) ] mitis: Matschie, 1916: 270 . Name combination.

[ Marmosa (Marmosa) ] chapmani: Cabrera, 1919: 36 .

[ Marmosa (Marmosa) ] fulviventer: Cabrera, 1919: 36 .

[ Marmosa (Marmosa) ] mitis casta: Cabrera, 1919: 38.

[ Marmosa (Marmosa) ] mitis mitis: Cabrera, 1919: 38 .

[ Marmosa (Marmosa) ] mitis pullidiventris: Cabrera, 1919: 38. Incorrect subsequent spelling of Marmosa mitis pallidiventris Osgood, 1912 .

[ Marmosa (Marmosa) ] robinsoni: Cabrera, 1919: 39 .

Marmosa mitis mitis: Tate, 1933: 115 .

Marmosa mitis casta: Tate, 1933: 116 .

Marmosa mitis fulviventer: Tate, 1933: 117 . Name combination.

Marmosa mitis robinsoni: Tate, 1933: 118 . Name combination.

Marmosa chapmani: Tate, 1933: 119 .

Marmosa mitis chapmani: Hershkovitz, 1951: 552 . Name combination.

Marmosa [( Marmosa )] robinsoni robinsoni: Cabrera, 1958: 24 . Name combination.

Marmosa mitis chapmani: Goodwin, 1961: 4 .

Marmosa mitis luridavolta Goodwin, 1961: 5 . Type locality ‘‘Speyside, Tobago, the West Indies.’’

Marmosa mitis grenadae: Goodwin, 1961: 8 . Name combination.

Marmosa robinsoni robinsoni: Musso, 1962: 165 .

Marmosa robinsoni: Handley, 1966: 755 . Part.

Marmosa robinsoni: Handley, 1976: 7 .

Marmosa robinsoni: Handley and Gordon, 1979: 68 .

Marmosa robinsoni fulviventer: Hall, 1981: 14 . Name combination.

Marmosa robinsoni grenadae: Hall, 1981: 14 . Name combination.

Marmosa robinsoni: Honacki et al., 1982: 23 . Part.

Marmosa robinsoni: O’Connell, 1983: 1 . Part.

Marmosa robinsoni: Pérez-Hernández, 1985: 61 .

Marmosa robinsoni robinsoni: Pérez-Hernández, 1989: 368 .

Marmosa robinsoni: Eisenberg, 1989: 39 . Part.

Marmosa robinsoni: Gardner, 1993: 18 . Part.

Marmosa (Marmosa) robinsoni: Pérez-Hernández et al., 1994: 40 .

Marmosa robinsoni: Reid, 1997: 48 . Part.

Marmosa robinsoni: Emmons, 1997: 26 . Part.

Marmosa robinsoni: Linares, 1998: 61 .

Marmosa robinsoni: Nowak, 1999: 21 . Part.

Marmosa robinsoni: López-Fuster et al., 2000: 829 .

Marmosa robinsoni: Brown, 2004: 65 . Part.

[ Marmosa robinsoni ] chapmani: Gardner, 2005: 9 .

[ Marmosa robinsoni ] fulviventer: Gardner, 2005: 9 .

[ Marmosa robinsoni ] grenadae: Gardner, 2005: 9 .

[ Marmosa robinsoni ] luridavolta: Gardner, 2005: 9.

[ Marmosa robinsoni ] robinsoni: Gardner, 2005: 9 .

M[armosa]. r.[obinsoni]. chapmani: Creighton and Gardner, 2008: 59 .

M[armosa]. r[obinsoni]. luridavolta: Creighton and Gardner, 2008: 59.

M[armosa]. r[obinsoni]. robinsoni: Creighton and Gardner, 2008: 59 .

TYPE MATERIAL: The holotype (by original designation, MCZ B7749 ) is a mature adult (age class 8) male preserved as a skin and skull ; although the skull lacks both ectotympanics, the specimen is otherwise in good condition.

TYPE LOCALITY: The holotype was collected by U.S. Army Lieutenant Wirt Robinson on 12 July 1895 on Isla Margarita, a large (ca. 1000 km 2) Caribbean island comprising the Venezuelan state of Nueva Esparta. Although the published type locality (‘‘Margarita Island’’) is imprecise, Robinson’s published itinerary ( Robinson and Richmond, 1896) states that he spent the week from 8 to14 July 1895 at El Valle de Espíritu Santo (10 ° 59 9 N, 63 ° 52 9 W, ca. 200 m above sea level; Paynter, 1982) on the lower slopes of Cerro Copey a few kilometers inland from Porlamar (10 ° 57 9 N, 63 ° 51 9 W) on the arid southeastern coast.

MORPHOLOGICAL DIAGNOSIS: Midrostral fur pale, usually contrasting sharply with darker fur of crown; dark median rostral stripe usually absent (an indistinct marking is occasionally present); dark facial mask usually not extending posteriorly to contact base of ear; dorsal body pelage variable but usually some shade of yellowish or grayish brown; dorsal cover hairs 8–11 mm in length, guard hairs 10–14 mm; gray-based ventral pelage conspicuous or not, usually restricted to sides of abdomen (but sometimes extending to the sides of lower chest, rarely to the inner parts of arms and legs), with yellowish hair tips; self-colored ventral pelage (extending as a continuous median strip of variable width from chin to anus) dark or light yellowish buff. Exposed skin of tail dark brown to yellowish brown, indistinctly bicolored (paler ventrally), without any consistent pattern of scale arrangement (both spiral and annular patterns coexisting); 14–22 scales/cm on dorsal surface at caudal midlength; caudal-scale hairs pale brown or whitish, detectable without magnification; central hair of each caudal-scale triplet as long as (or slightly longer) than two scales. Gular gland present. Mammae at least 6–1–6 5 13 (but perhaps sometimes as many as 9–1–9 5 19; see table 3). Lateral and medial carpal tubercles present in mature adult males; medial carpal tubercle long or short (reaching the base of the pollex or not), with globular proximal part and comma-shaped distal part.

Rostral process of premaxillae short, about half as long as I1 height. Orbitosphenoid-alisphenoid suture somewhat less than twice as long as sphenorbital fissure height in lateral view. Supraorbital ridges straight or slightly divergent posteriorly, tending to become thick and dorsally reflected in mature adults but seldom produced laterally to form distinct postorbital processes; temporal ridges usually conspicuous and converging posteriorly, sometimes forming a low sagittal crest in old adults. Palatine fenestrae consistently present and usually large (typically as a single rounded hole on each side); posterolateral palatal foramina large, usually similar in length to M3 (measured across paracone-metacone). Tympanic wing of alisphenoid usually large and globular; medial process of ectotympanic usually well developed. I1 hypsodont; crown of I2 sharply defined in relation to root; C1 without accessory cusps; preparacrista connected to stylar cusp B on M1–M3; stylar cusps D and E usually separated by a distinct notch.

COMPARISONS: Morphological comparisons of Marmosa robinsoni with M. mexicana , M. zeledoni , and M. isthmica are provided in the preceding accounts. Comparisons of M. robinsoni with M. xerophila , M. simonsi , and M. rubra are provided below.

Marmosa robinsoni closely resembles M. xerophila in size and qualitative characters. Although robinsoni averages larger than xerophila in most external measurements (tables 4, 5), the two species overlap broadly in postcranial dimensions and cannot be identified on this basis alone. In side-by-side comparisons of skins, the dorsal pelage of robinsoni is usually darker and somewhat less grayish than that of xerophila , and the ventral pelage of robinsoni is usually yellowish (‘‘cream-colored’’ sensu Handley and Gordon, 1979) whereas the ventral pelage of xerophila is usually whitish. Also, the lateral zones of gray-based ventral fur are more conspicuous in robinsoni than they are in xerophila because the pale hair tips are shorter (the longer pale hair tips of xerophila more effectively conceal the gray hair bases when the ventral fur is unruffled). Marmosa robinsoni averages larger than M. xerophila in almost all measured craniodental dimensions (tables 6, 7), with minimal overlap in observed ranges for Maxillary Tooth Row (MTR), Upper Molar Series (UMS), and Lower Molar Series (LMS).2 Visual comparisons of skulls suggest that the rostrum is proportionately longer and more slender, and that the orbits are proportionately smaller in robinsoni than in xerophila . The qualitative cranial trait that differs most consistently between the species is the rostral process of the premaxillae, which, although small, is almost always distinct in robinsoni ; by contrast, the rostral process seems to be

2 Despite such overlap, discriminant function analyses of craniodental measurements have already demonstrated that robinsoni and xerophila are morphometrically distinct (López- Fuster et al., 2002).

consistently absent in xerophila . Additionally, postorbital processes are less often distinct in robinsoni than they are in xerophila , and the temporal ridges are less strongly convergent posteriorly in robinsoni than they are in like-aged specimens of xerophila .

Marmosa robinsoni can be distinguished unambiguously from M. simonsi in numerous qualitative characters despite their similarity in external and craniodental measurements (tables 4–7). Whereas the dark facial mask of robinsoni seldom extends posteriorly to the base of the ear, the mask often extends continuously from the ear to the mystacial region in simonsi , some specimens of which closely resemble mexicana in this respect. Dorsal and ventral pelage coloration is also widely divergent in these species: the dorsal pelage is usually some shade of yellowish brown, and a broad streak of self-colored (usually yellowish) ventral fur invariably extends from chin to anus in robinsoni ; by contrast, the dorsal pelage is distinctly grayish and the ventrum is almost entirely covered by gray-based fur in simonsi (only the chin and groin of which are self-colored). The tail, which is uniformly dark (brownish) in robinsoni , is boldly marked with white in simonsi . Postorbital processes are usually absent or indistinct in robinsoni , but they are consistently well developed and often large in simonsi . The temporal ridges are better developed and more strongly convergent posteriorly (sometimes forming a low saggital crest) in robinsoni than they are in like-aged specimens of simonsi (which never develops a saggital crest).

Marmosa robinsoni is unlikely ever to be confused with M. rubra , from which it differs externally by its relatively shorter tail and larger ears (tables, 4, 5), lack of a dark midrostral streak (usually present in rubra ), yellowish- (versus reddish-) brown dorsal pelage, presence (versus absence) of a gular gland, inconsistent (versus spiral) caudal scale patterning, and much longer caudalscale hairs. Marmosa robinsoni differs craniodentally from M. rubra by having a short (versus long) rostral process of the premaxillae; by having palatine fenestrae (which are absent in rubra ); by having large, globular alisphenoid tympanic processes (the alisphenoid bullae are small and laterally com- pressed in rubra ); by having a small but usually distinct medial process of the ectotympanic (absent in rubra ); and by the preparacrista connecting to stB on M1–3 (the preparacrista usually connects to stA in rubra ).

Marmosa robinsoni also merits comparison with M. murina —a distantly related species not treated in this report—with which it occurs sympatrically in northern Colombia, northern Venezuela, and on the island of Tobago (see below). Among other characters, these species differ in caudal scale patterning (inconsistent in robinsoni , spiral in murina ), carpal tubercles (present in mature adult male robinsoni , absent in murina ), caudalscale hairs (macroscopically visible in robinsoni but not in murina ), the rostral process of the premaxillae (shorter in robinsoni than in murina ), occurrence of palatine fenestrae (present in robinsoni , absent in mainland forms of murina ), shape of the tympanic process of the alisphenoid (smoothly globular in robinsoni , laterally compressed and sometimes pointed ventrally in murina ), medial process of the ectotympanic (well-developed in robinsoni , absent or indistinct in murina ), and stylar cusps D and E (usually separated by a distinct notch in robinsoni but not in murina ).

GEOGRAPHIC DISTRIBUTION AND SYM- PATRY: The known distribution of Marmosa robinsoni extends from Finca Santa Clara (locality 109; fig. 25) in the western Panamanian province of Chiriquí eastward across the isthmus to Colombia and northern Venezuela. Although most Venezuelan specimens are from north of the Orinoco River, we examined one specimen (AMNH 16132) from Ciudad Bolívar (locality 236) on the south (right) bank of the river in Bolívar state. The species is also known from several islands on the continental shelf of Central America (e.g., Isla del Rey, Isla Saboga) and South America (Isla Margarita, Trinidad, and Tobago), and from the Caribbean island of Grenada.

Marmosa robinsoni occurs in a wide variety of habitats from sea level to 2600 m elevation including lowland and montane moist forests, lowland dry forests, mangroves, savannas, and xeric shrublands. Among the collecting localities mapped in figure 25, approximately 32% correspond to open habitats (llanos, xeric shrublands, etc) from which about 45% of the specimens examined were collected. Large numbers of museum specimens with the same locality data suggest that this species is often among the most abundant nonvolant small mammals in such environments ( Handley and Gordon, 1979).

The range of Marmosa robinsoni partially overlaps the distributions of M. mexicana , M. zeledoni , and M. isthmica in Panama, as described above in the accounts of those species. The range of M. robinsoni also overlaps the distribution of M. xerophila in the arid and semiarid landscapes surrounding the Gulf of Venezuela in the Venezuelan states of Falcón and Zulia, and in the adjacent department of La Guajira, Colombia. However, there appear to be no collecting localities where both species have been taken sympatrically. The only other congeneric species with a distribution that overlaps the range of M. robinsoni is M. murina , which also occurs in northern Colombia, northern Venezuela, and on the island of Tobago ( Goodwin, 1961; Handley, 1976; Pérez-Hernández, 1989; Linares, 1998). In Venezuela, M. robinsoni and M. murina have been collected sympatrically near Urama (locality 239), Ciudad Bolívar (locality 236), and San Augustín (locality 261); on the island of Tobago, these species have been collected together at Charlotteville (locality 294) and Speyside (locality 295).

GEOGRAPHIC VARIATION: Available population samples of Marmosa robinsoni exhibit noteworthy geographic variation in size and pelage color. Insular specimens—such as those from Trinidad ( chapmani ), Tobago (luridavolta), and Grenada ( grenadae )—tend to be larger, on average, than specimens from the adjacent mainland regardless of the habitats in which they were collected. According to López-Fuster et al. (2000), however, mainland Venezuelan specimens from agricultural landscapes and disturbed forests exhibit larger craniodental dimensions than those from cloud forests and gallery forests. In general, specimens of M. robinsoni from humid habitats (including mangroves and high altitude cloud forests) tend to have darker pelage (grayish brown washed with orange or dark yellow dorsally, and orangish buff or dark yellowish buff ventrally) as well as dark-brown ears, feet, and tail. By contrast, specimens from drier, more open habitats (e.g., dry forests, savannas, and xeric shrublands) tend to have paler pelage (light grayish brown washed with yellow dorsally, and yellowish buffy or cream buffy ventrally) and light-brown ears, feet, and tail ( Tate, 1933; Handley and Gordon, 1979).

TAXONOMIC HISTORY: The first published reference to material identifiable as Marmosa robinsoni was Allen and Chapman’s (1893) report of Didelphis (Micoureus) murina from Trinidad. Subsequently, Thomas (1896) and Allen and Chapman (1897) also misidentified specimens of M. robinsoni as M. murina .

Bangs (1898a) described Marmosa robinsoni based on three specimens from Isla Margarita ( Venezuela). Later, and in the same volume of the Proceedings of the Biological Society of Washington, Bangs (1898b) described Marmosa mitis based on 27 specimens from Pueblo Viejo ( Colombia). Although the type series of mitis and robinsoni exhibit obvious external and cranial similarities, Bangs (1898b) provided comparisons only between mitis and murina . Because Bangs did not compare mitis with robinsoni , and because he provided only superficial descriptions of the cranial morphology of both taxa, several subsequent authors failed to recognize their close relationship to each other and to other related nominal taxa described in the years that followed.

Tate (1933) was the first author to recognize robinsoni and mitis as conspecific, treating them as valid subspecies along with casta (from mainland Venezuela) and fulviventer (from Isla del Rey, Panama). Howev- er, Tate erroneously used mitis as the senior name, and he recognized chapmani (from Trinidad) as a separate valid species. Finally, Tate grouped M. chapmani , M. mitis , M. ruatanica (5 M. mexicana), and M. simonsi as members of the Mitis Section of his Murina Group of Marmosa (table 1).

As explained in the introduction, Hershkovitz (1951) treated all of the species in Tate’s (1933) Mitis Section, together with isthmica and mimetra , as subspecies of Marmosa mitis . This broad concept of M. mitis was subsequently endorsed by Cabrera (1958) who, however, correctly used robinsoni as the oldest available name. Cabrera’s taxonomy was then adopted by Hall and Kelson (1959) and effectively persists (with minor modifications) to the present day ( Gardner, 2005; Creighton and Gardner, 2008).

REMARKS: Despite the marked geographic variation in size and pelage color noted above, specimens that we refer to Marmosa robinsoni resemble one another closely and differ as a group from other valid species of Marmosa as diagnosed herein. Although molecular data would be welcome to assess the genetic distinctness of and phylogenetic relationships among the many named forms here treated as junior synonyms of M. robinsoni (including casta, chapmani , fulviventer , grenadae , luridavolta, mitis , nesaea , and pallidiventris), only morphological inferences are possible at present.

The larger body size of island populations of small nonvolant mammals by comparison with their mainland counterparts is a welldocumented phenomenon for which a multitude of explanatory hypotheses have been proposed ( Crowell, 1983; Lomolino, 1985; Adler and Levins, 1994; McNab, 1994). Several nominal taxa have been described for insular populations of M. robinsoni , including the nominotypical form (from Isla Margarita), chapmani and nesaea ( Trinidad) , fulviventer (Isla del Rey), grenadae ( Grenada) , and luridavolta ( Tobago). Our examination of holotypes and other representative material of these taxa suggest that they are nothing more than large island forms with habitat-correlated coat color differences similar to those observed among many other widespread species of small mammals.

Most continental forms average smaller than typical (insular) M. robinsoni , but the young adult female holotype of pallidiventris (FMNH 18692) is exceptionally small by comparison with the mature adult male holotypes of casta (BMNH 11.5.25.184) and mitis (MCZ B-8123), a difference plausibly attributable to age and sexual dimorphism. Continental forms also differ from typical robinsoni in pelage color. The tropical moist forest ecoregions ( Olson et al., 2001) where the holotypes of the former were collected plausibly explain their darker pelage when compared with the type material of robinsoni from the predominantly arid environments of Isla Margarita. Although the holotype of mitis has wider and more conspicuously graybased ventral fur than the holotype of casta, comparable variation in ventral pelage markings is observable among other species of Marmosa and is not, in our opinion, a sufficient basis for taxonomic diagnosis.

SPECIMENS EXAMINED (N 5 541): Without locality data (BMNH 95.3.9.6). PANA- MA —No other locality data (USNM 303051). Canal Zone, no other locality data (USNM 318316), Balboa (USNM 456818, 456822), Fort Kobbe (USNM 298697, 298698, 300329, 300330, 301141, 303049), Miraflores (USNM 396415), Quarry Heights (USNM 303281– 303283). Chiriquí, Near Escopeta Camp (5 23–25 km NNE San Felix: USNM 541000, 541002; 5 Colorado Camp: USNM 541324), Finca Santa Clara (USNM 520772), Tolé (USNM 331071). Coclé, Río Hato (USNM 331069). Panamá, Pacora (USNM 305146), Isla Saboga (5 Saboga Island: MCZ 10809), Isla del Rey (5 San Miguel Island: FMNH 34071; MCZ B8435 [holotype of Marmosa fulviventer Bangs, 1901 ], B8437, B8438). Veraguas, Santa Fé (5 Río Santa Maria : USNM 304696–304709). COLOMBIA — Atlántico, Barranquilla (MVZ 135234–135243; 5 ‘‘Barranquilla’’, place of shipment: MVZ 183339; 5 Vicinity Barranquilla: MVZ 183334–183338). Bolívar, San Juan Nepomuceno (FMNH 69315). Cesar, El Salado (USNM 280814– 280816), El Orinoco (5 Río Cesar: USNM 280820, 280886–280888; 5 Río Guaimaral: USNM 280817, 280819), San Sebastián de Rábago (5 San Sebastián: FMNH 69320, 69321), Valledupar (5 Aguas Verdes: USNM 280818). Cundinamarca, Bogotá (AMNH 143521). Huila, Naranjal (5 Valle de Suaza: USNM 541857–541861, 543120), Villavieja (MVZ 113366, 113367, 113833–113835– 113840). La Guajira, El Pueblito (5 Pueblo Viejo: FMNH 18509; BMNH 9.4.15.18– 9.4.15.20; MCZ B8117–B8122, B8123 [holotype of Marmosa mitis Bangs, 1898 ], B8125– B8127, B8132, B8143; USNM 85531, 85532; 5 Santa Marta : FMNH 18508), La Concepción (FMNH 18507), Las Marimondas (USNM 280876–280880, 280882, 280883, 280885), San Miguel (FMNH 18506), Villanueva (USNM 280853–280875; 5 Sierra Negra: USNM 280821–280852). Magdalena, Bonda (AMNH 14610, 14611, 15357–15361, 23273–23276, 23280, 23281, 23292, 23627), Colonia Agrícola de Caracolicito (USNM 280806), Mamatoco (AMNH 15362), Minca (AMNH 23293), Palomino (USNM 85533), Pueblo Bello (USNM 280807–280813), Santa Marta (AMNH 244887), Taganga (AMNH 15363). Norte de Santander, Cúcuta (FMNH 18692 [holotype of Marmosa mitis pallidiventris Osgood, 1912 ]). Santa Marta , no other locality data (AMNH 244887). Tolima, Honda (AMNH 34602–34604), Mariquita (AMNH 207766). VENEZUELA — Apure, Hato El Frío (USNM 448524). Aragua, Camp Rangel (USNM 314171), Ocumare de La Costa (USNM 517271–517280), Rancho Grande (USNM 517262–517270). Barinas, Altamira (USNM 418540). Bolívar, Ciudad Bolívar (AMNH 16132). Carabobo, El Trompillo (BMNH 14.9.1.86–14.9.1.97), San Esteban (AMNH 31532; BMNH 11.5.25.178–11.5. 25.183, 11.5.25.184 [holotype of Marmosa mitis casta Thomas, 1911 ], 11.5.25.185, 11.5.25.187; 5 San Esteban Valley: BMNH 11.5.25.186), Urama (USNM 372938–372940, 372942–372944, 372947). Distrito Federal, Caracas (AMNH 130586–130589). Falcón, Cerro Santa Ana (5 15 km SSW Pueblo Nuevo: USNM 442907; 5 49 km N and 32 km W Coro: USNM 443870–443874, 443877, 443880–443888, 443890–443896), Hacienda Socopito (5 20 km S and 98 km E Maracaibo: USNM 443801; 5 24 km S and 94 km E Maracaibo: USNM 418531, 418532), Mirimire (USNM 406953). Guárico, Estación Biológica de los Llanos (USNM 385052; 5 9 km SE Calabozo: USNM 442908, 443906, 443908, 443910; 5 7 km S and 5 km E Calabozo: USNM 443897, 443901–443905, 443911), Hato Las Palmitas (USNM 385053– 385056, 418518, 418519, 443794, 443797, 443798, 443800). Lara, Caserio Boro (USNM 443913), Puerta Vieja (USNM 443914), La Concordia (USNM 443912), Río Tocuyo (AMNH 130577–130585, 130600). Mérida, Mérida (BMNH 2.3.4.8; 5 Cafetos de Chama: AMNH 24320, 24323, 24324, 33166; BMNH 5.1.1.6), Milla (5 Cafetos de Milla: BMNH 98.7.1.21; USNM 149005), Pedregosa (BMNH 98.7.1.19). Miranda, Curupao (USNM 385057–385060), San Andrés (5 8 km SSE Caracas: USNM 385047–385049). Monagas, Hato Mata de Bejuco (5 47 km SE Maturin: USNM 385068–385072; 5 54–55 km SE Maturín: USNM 443915–443917, 442720), Ipuré (BMNH 0.5.1.59), San Agustín (USNM 406951), San Antonio de Maturín (5 San Antonio: AMNH 69939, 69940). Nueva Esparta, Isla Margarita (5 Margarita Island: BMNH 99.11.12.1; MCZ B7749 [holotype of Marmosa robinsoni Bangs, 1898 ]; USNM 63209, 63210, 63212), Salamanca (USNM 388381, 388388–388397, 388399, 388400; 5 3 km S La Asunción: USNM 388398). Portuguesa, Guanarito (AMNH 266951– 266954). Sucre, Campo Alegre (BMNH 0.5.1.58), Cuchivano (AMNH 69938), Cumaná (USNM 388377–388379, 388385, 388386), Guaraúnos (AMNH 257208– 257210). Trujillo, Isnotú (5 Near Isnoto: USNM 370050), Agua Viva (USNM 371304), Agua Santa (USNM 370048, 370049), El Dividive (USNM 371305, 371315, 371316), La Ceiba (5 Hacienda Valle Verde: USNM 371317), Valera (FMNH 22175). Zulia, Cerro Azul (5 17 km N and 55 km W Maracaibo: USNM 443807; 5 18 km N and 56 km W Maracaibo: USNM 443802– 443804; 5 39 km NW La Paz: USNM 443805, 443806), Novito (5 3 km S and 19 km W Machiques: USNM 418529, 418530), Río Chama (BMNH 98.7.1.20). TRINIDAD AND TOBAGO —No other locality data (AMNH 6127; USNM 197042), El Cerro del Oropuche (5 Orepouche Heights: AMNH 31229–31231), Bush Bush Forest (AMNH 188357, 189314–189316, 204855–204857, 206595–206597, 206761, 206762, 206764– 206768). ‘‘Trinidad Island’’ (BMNH 95.3.9.7, 97.6.7.25, 97.6.7.26). Arima, Arima (5 St. Patricks: AMNH 169671, 188355). Caroni, Caparo River (5 Caparo Valley: BMNH 97.6.7.24 [holotype of Marmosa nesaea Thomas, 1911 ]), Caparo (AMNH 7426, 7429, 7660/ 6046–7664/6050). Saint Andrew, no other locality data (AMNH 186440), Cumaca (AMNH 188354, 208996, 208999–209003, 212128–212130, 214425–214438, 214444, 234963–234970), Cumuto (AMNH 212303– 212305), Sangre Grande (AMNH 173984, 173996, 174000, 174007, 174008, 174012, 174162, 188356; 5 El Reposo Rd.: AMNH 173990; 5 Maingot Estate: AMNH 173998), Turure Forest (AMNH 214440, 234972, 234976), Upper Fishing Pond (5 Fishing Pond: AMNH 173997). Saint George, Brazil Village (AMNH 208997, 208998), Caura (AMNH 7665/6051, 7666/6052 [holotype of Marmosa chapmani Allen, 1900 ], 7667/6053– 7670/6056, 7672/6058, 7674/6060–7676/6062; USNM 85556; 5 Caura Mts.: AMNH 7430). Saint Patrick, Aripo Savanna (5 Aripo Valley: BMNH 35.2.10.1), Cedros Point (5 Cedros: AMNH 234960, 234961; 5 Cedros Ward: AMNH 214424). Tobago, Charlotteville (AMNH 259973, 259983; USNM 537898, 537899, 538075–538078), Speyside (AMNH 184845, 184846, 184848 [holotype of Marmosa mitis luridavolta Goodwin, 1961 ], 184849). Victoria, Princestown (AMNH 4799–4802, 6046, 6049, 6121, 6123, 6045/4767, 6047/ 4768, 6048/47669, 6050/4770–6053/4773, 6055/ 4775, 6056/4776, 6058/4778), Savana Gran- de (BMNH 1939.3270). GRENADA – Saint George, Annandale (BMNH 87.6.30.5 [holotype of Marmosa grenadae Thomas, 1911 ]).

Marmosa xerophila Handley and Gordon, 1979 Figures 23, 24

Marmosa xerophila Handley and Gordon, 1979:

68. Type locality ‘‘La Isla, 15 m, near Cojoro,

37 km NNE Paraguaipoa, Dpto. Guajira,

Colombia.’’ Marmosa xerophila: Honacki et al., 1982: 23 . Marmosa xerophila: Pérez-Hernández, 1989: 369 . Marmosa xerophila: Eisenberg, 1989: 41 . Marmosa xerophila: Gardner, 1993: 19 . Marmosa (Marmosa) xerophila: Pérez-Hernández

et al., 1994: 41. Marmosa xerophila: Linares, 1998: 65 . Marmosa xerophila: Nowak, 1999: 21 . Marmosa xerophila: López-Fuster, 2002: 201 . Marmosa xerophila: Brown, 2004: 69 . Marmosa xerophila: Gardner, 2005: 10 . Marmosa xerophila: Creighton and Gardner, 2008:

61.

TYPE MATERIAL: The holotype (by original designation, USNM 443819) is a mature adult (age class 7) male specimen preserved as a skin in good condition and a skull that is missing the left ectotympanic but is otherwise complete.

TYPE LOCALITY: The holotype was collected on 28 June 1968 at a locality called ‘‘La Isla’’ near Cojoro (gazetteer entry 163) in the Colombian department of La Guajira by a Smithsonian Venezuelan Project field team consisting of Norman E. Peterson, Fred P. Brown, Jr., and John O. Matson, whose field notes were the basis for Handley’s (1976: 67) published description of coastal-desert habitats near Cojoro.

MORPHOLOGICAL DIAGNOSIS: Midrostral fur pale, usually contrasting sharply with darker fur of crown; dark median rostral stripe absent or inconspicuous; dark facial mask not extending posteriorly to contact base of ear; dorsal body pelage pale, usually some shade of faded yellowish brown or light grayish brown; dorsal cover hairs about 7 mm in length, guard hairs about 10 mm; graybased ventral pelage restricted to the sides of abdomen, with whitish or yellowish hair tips; self-colored ventral pelage (extending as a wide median stripe from chin to anus) whitish or yellowish. Exposed skin of tail grayish brown, indistinctly bicolored (paler ventrally), without any clear pattern of scale arrangement (both spiral and annular patterns coexisting); 14–16 scales/cm on dorsal surface at caudal midlength; caudal-scale hairs usually whitish and detectable without magnification; central hair of each caudalscale triplet as long as (or slightly longer than) two scales. Gular gland present. Mammae at least 5–1–5 5 11 (but perhaps as many as 6–1–6 5 13; see table 3). Lateral and medial carpal tubercles present in mature adult males; medial carpal tubercle long or short (reaching the base of pollex or not), with subequal but recognizable proximal and distal parts.

Rostral process of premaxillae absent. Orbitosphenoid-alisphenoid suture somewhat less than twice as long as sphenorbital fissure height in lateral view. Supraorbital ridges parallel or slightly divergent posteriorly, usually thick and dorsally reflected in mature adults, sometimes produced laterally as more or less distinct postorbital processes; temporal ridges conspicuous, usually strongly convergent posteriorly and sometimes joining to form a low sagittal crest in old adults. Palatine fenestrae consistently present and well developed (typically as a single rounded hole on each side); posterolateral palatal foramina large, similar in length to M3 (measured across paracone-metacone) or even longer. Tympanic wing of alisphenoid usually large and globular; medial process of ectotympanic well developed. I1 hypsodont; crown of I2 sharply defined in relation to root; C1 without accessory cusps; preparacrista connected to stylar cusp B on M1–M3; stylar cusps D and E usually separated by a distinct notch.

COMPARISONS: Morphological comparisons of Marmosa xerophila with M. mexicana , M. zeledoni , M. isthmica , and M. robinsoni are provided in the preceding accounts. Marmosa xerophila differs from M. simonsi , M. rubra , and M. murina in all of the same characters by which M. robinsoni differs from those species, except that the rostral process of the premaxillae (short in M. robinsoni ) is entirely lacking in M. xerophila .

GEOGRAPHIC DISTRIBUTION AND SYM- PATRY: The known geographic distribution of Marmosa xerophila is restricted to the coastal deserts surrounding the Golfo de Venezuela (including the Península de Paraguaná) in the Venezuelan states of Falcón and Zulia and in the Colombian department of La Guajira (fig. 26). The habitats in which specimens have been collected correspond to the ‘‘Paraguaná Xeric Scrub’’ and the ‘‘Guajira/Barranquilla Xeric Scrub’’ ecoregions of Olson et al. (2001). Although the species is not known from the Netherlands Antilles, it may once have occurred on the continentalshelf island of Aruba, where several other species of small mammals that now inhabit arid or semiarid mainland habitats have been reported as subfossils ( Hooijer, 1960, 1967).

Although the range of Marmosa xerophila is completely overlapped by the macrogeographic distribution of M. robinsoni , these species have yet to be recorded in sympatry. The range of M. xerophila is also contained within the macrogeographic distribution of M. murina , a rainforest species not treated in this report.

GEOGRAPHIC VARIATION: According to López-Fuster et al. (2002), Marmosa xerophila is a morphometrically homogeneous species that exhibits no noteworthy geographic differences in measured dimensions. Although our observations and data are broadly consistent with their assessment, we agree with Handley and Gordon (1979) that specimens from the west coast of the Golfo de Venezuela (in the Venezuelan state of Zulia and the Colombian department of La Guajira) have visibly smaller bullae than those on the east coast (in the Venezuelan state of Falcón).

TAXONOMIC HISTORY: Remarkably, no specimens of this locally abundant mouse opossum appear to have been collected prior to the Smithsonian Venezuelan Project expeditions to the northwestern coastal lowlands of Venezuela in 1968. Therefore, the brief taxonomic history of Marmosa xerophila effectively began with Handley and Gordon’s (1979) original description, which was based on the Colombian holotype and 245 paratypes from the localities listed below. Despite a close resemblance to M. robinsoni , the distinctness of M. xerophila has not been questioned by subsequent researchers.

SPECIMENS EXAMINED (N 5 105): CO- LOMBIA— La Guajira, Cojoro (5 37–55 km NNE Paraguaipoa: USNM 443812–443818 , 443819 [holotype of Marmosa xerophila Handley and Gordon, 1979 ], 443820– 443831). VENEZUELA — Falcón, Capatárida ( USNM 442721–442727 , 442729– 442731 , 442733–442735 , 442744 , 443918– 443925 , 443927–443929 , 443931 , 443936– 443938 , 443940–443942 , 443946 , 443947 , 443951 , 443952 , 443955–443957 , 443959 , 443960 , 443963–443972 , 443974–443978 ; 5 18 km WSW Capatárida: USNM 442728 ), Moruy (5 49 km N and 33 km W Coro: USNM 443834–443848 , 443851 ), Yabuquiva (5 25 km SW Pueblo Nuevo: USNM 442906 ; 5 48 km N and 46 km W Coro: USNM 443852 , 443854–443856 , 443862 , 443863 , 443868–443869 ). Zulia, Paraguaipoa (5 114 km N and 32 km W Maracaibo: USNM 443810 , 443811 , 443832 ) .