Tylomyinae Reig 1984

Wilson, Don E. & Reeder, DeeAnn, 2005, Order Rodentia - Family Cricetidae, Mammal Species of the World: a Taxonomic and Geographic Reference (3 rd Edition), Volume 2, Baltimore: The Johns Hopkins University Press, pp. 955-1189 : 1186

Tylomyinae Reig 1984

Tylomyinae Reig 1984 , Revista Brasil. Genet., 7 (2): 338.

Synonyms: Tylomyini McKenna and Bell 1997 .

Genera: 4 genera with 10 species:

Genus Nyctomys Saussure 1860 (1 species)

Genus Otonyctomys Anthony 1932 (1 species)

Genus Ototylomys Merriam 1901 (1 species)

Genus Tylomys Peters 1866 (7 species)

Discussion: Emended definition—Medium to large-sized arboreal cricetid rodents with tail slightly longer than head and body; four mammae arranged as two inguinal pairs; hindfoot short and broad, digit V nearly equal to II-IV, plantar pads large and closely approximate, ungual tufts present; interorbit cuneate, supraorbital shelves pronounced, dorsally reflected, continuing (in adults) as well-defined temporal ridges; interparietal conspicuous, long and wide, laterally contacting squamosal; zygomatic plate relatively narrow, dorsal notch absent or weakly suggested; tegmen tympani adnate to squamosal (Voss, 1993); alisphenoid strut present, postglenoid foramen tiny, subsquamosal fenestra absent, hamular process undefined ( Carleton, 1980); palatal conformation short-wide ( Hershkovitz, 1962), parapterygoid fossa shallow and relatively narrow; mesopterygoid fossa typically fully ossified, sphenopalatine vacuities absent or inconspicuous slits ( Carleton, 1980); molars brachyodont, strongly cuspidate with principal cones opposite, mesoloph(id) and other accessory enamel ridges well developed; M2 four-rooted, m3 large and in size and coronal topography resembling m2; 1 st rib articulating only 1 st thoracic vertebra, humerus with entepicondylar foramen, trochlear process of calcaneum broad and positioned proximally ( Carleton, 1980); stomach unilocular-hemiglandular, gall bladder absent, caecum long and elaborately infolded ( Carleton, 1973, 1980); glans penis short and wide with rudimentary to deep crater, spines large and widely spaced, baculum shorter than glans, with moderate cartilaginous spine but without lateral bacular digits ( Hooper, 1960; Hooper and Musser, 1964 a). Contents— Nyctomys Saussure, 1860 ; Otonyctomys Anthony, 1932 ; Ototylomys Merriam, 1901 ; Tylomys Peters, 1866 .

Vorontsov (1959) arranged these genera as members of Oryzomyini (including "thomasomyines"), within a broadly defined Cricetinae . Hooper (1960) first advanced a family-group concept for these Middle American endemics, then comprising only Tylomys and Ototylomys which he associated as one group of four within North American genera having a "simple" phallus, the neotomine-peromyscines (= Neotominae sensu Reig, 1980 , and others). Subsequently viewed either as early offshoots of a lineage leading to Neotoma ( Hooper and Musser, 1964 a) or as an older clade, possibly including Nyctomys , basal to the divergence of neotomine-peromyscines and sigmodontines ( Carleton, 1980). Reig (1984) nomenclaturally formalized the rank as subfamily and listed its generic contents; McKenna and Bell (1997) used it as tribe within Sigmodontinae sensu lato.

Although tylomyines can be morphologically circumscribed, as here defined, abundant traits indicate that Tylomys Ototylomys (Tylomyini; see emended definition under Tylomys account) and Nyctomys Otonyctomys ( Nyctomyini new tribe; see Nyctomys account) are themselves distantly related (see below). While various kinds of evidence do point to the antiquity of certain of these genera ( Arata, 1964; Carleton, 1980; D’Elía et al., 2003; Engel et al., 1998; Haiduk et al., 1988; Hooper and Musser, 1964 a; Sarich, 1985; Steppan, 1995; Voss and Linzey, 1981), no recent study has mustered the taxonomic sampling needed to critically test the several questions of monophyly at issue, whether early diverging members of Neotomini ( Hooper and Musser, 1964 a), a primitive clade apart from Neotominae and Sigmodontinae ( Carleton, 1980; Reig, 1984), or another phyletic topography as yet unrecognized in our classification .