Pattonomys Emmons, 2005

Emmons, Louise H. & Fabre, Pierre-henri, 2018, A Review of the Pattonomys / Toromys Clade (Rodentia: Echimyidae), with Descriptions of a New Toromys Species and a New Genus, American Museum Novitates 2018 (3894), pp. 1-52: 27-29

publication ID 10.1206/3894.1


persistent identifier

treatment provided by


scientific name

Pattonomys Emmons, 2005


Pattonomys Emmons, 2005  

TYPE SPECIES: Nelomys semivillosus I. Geoffroy St.   -Hilaire, 1838.

CONTENTS: Four valid species, as diagnosed below.

DIAGNOSIS: A genus of large, arboreally adapted Echimyidae   ( tables 5, 6). Dorsal pelage with strong, wide, gray-based aristiform spines that narrow to sharp tips; some spines entirely black or dusky tipped, others with dark subterminal bands and contrasting white tips that impart a pronounced speckled appearance ( fig. 4B View FIG ). Prominent pale postauricular patches ( fig. 14B View FIG ). Cranium generally like that of Makalata   and Echimys   , short and broad, with more or less expanded, winglike supraorbital shelves that curve upward from the frontal bones ( figs. 7E–H View FIG , 9E–H View FIG , 10E–H View FIG ; see also Emmons, 2005: figs. 11 View FIG , 14 View FIG ). Upper cheekteeth with widely open flexi, greatly anteroposteriorly expanded protocone and posteroloph (probably metaloph and posteroloph combined), and a markedly oblique paraflexus on dP4 ( fig. 12E–G View FIG ). These expanded lophs are accentuated with wear. The four lophs of dP4–M2 are markedly unequal in length and width: the anteroloph is broad and squared lingually, tapering labially; and the posteroloph is pointed labially and strongly curved along the posterior margin of the tooth. Lower premolar tetralophodont, with two labial and two lingual flexids ( fig. 12E–G View FIG ).

DESCRIPTION: Spines wide, sharp, and stiff, with tips not drawn out into long hairlike processes but end in microscopic hairs ( fig. 4B View FIG ). White-tipped spines are sprinkled singly among the lateral and dorsal pelage from shoulder or midback to rump, increasing posteriorly in number and in the length of pale tips. Pale-tipped spines sparsely and evenly distributed over the speckled rump. Dorsal spines mixed with fine, ochraceous yellow to orange setiform bristles and sparse dull reddish or yellow-ochraceous underhairs; pelage slate-gray based. Head, neck, and shoulders grizzled gray lined with black, in a mixture of long, narrow, dusky and whitish aristiforms ( fig. 14B View FIG ). Sides grayish from head to flank between gradually or sharply demarcated pale venter and yellowish or reddish-brown tinged middorsal pelage. Ear tips with an inconspicuous, sparse fringe of long fine, salient hairs. Dorsal pelage extends onto the tail base to about the hind feet of study skins; distal tail evenly covered above and below to its tip with fine, monocolored white to red-brown hairs that do not cover scales but curl outward, so that the tail looks distinctly hairy ( fig. 5A View FIG ). Vibrissae robust, dense, and black, the longest reaching to shoulder when laid back. Two pairs of lateral mammae lie in the dorsal pelage field, one about midway between the limbs, the other just anterior to the flank. Hind feet, based only on P. carrikeri   , with four small, ovoid digital pads and a fifth small outer pad budding laterally from D4. Hypothenar pad joined to large naked heel pad with only a slight depression between them ( fig. 6B View FIG ); thenar pad elongate and slender, separated from the joined hypothenar and heel pads by a deep, narrow groove containing palmar tubercles. Plantar surfaces between pads with a few inconspicuous tubercles; digital pads bordered by distinct rings or collars of tubercles ( fig. 6B View FIG ); forefoot digital pads also bordered by indistinct collars of tubercles, but the central palm with few or none. On the cranium, the frontal-squamosal suture at the back of the orbit is raised in a sharp ridge ( fig. 7E–H View FIG ). Mastoid processes short, to the middle or lower edge of the auditory meatus, adpressed to the bulla, and enclosed to the tip by occipital bone ( fig. 7E–H View FIG ) and see also Emmons (2005: 263, fig. 5 View FIG ). Postglenoid foramen enclosed below by the petrosal bone in an anteriorly facing tube; the salient ventral lip of the auditory meatus is usually visible in dorsal aspect ( fig. 9G View FIG ), and is further extended in mature individuals by two overlapping additional bony rings that cup the meatus ventrally and laterally, but are incomplete dorsally ( fig. 15A View FIG ). These are not fused and can be lost in skin preparation. Nasal bones in dorsal aspect flared distally, slightly pinched in medially, and about squared or slightly rounded posteriorly ( fig. 9E–H View FIG ). Incisive foramina small, narrow, and slightly ovoid, with deep grooves and ridges leading onto the anterior palate to between the first or second cheekteeth ( fig. 10E–H View FIG ). Maxillary toothrows nearly parallel. Mandible with a low coronoid process only slightly shorter than the narrow condyloid process, and a shallow sigmoid notch ( fig. 7E–H View FIG ). Mandibular foramen in a fossa arising low on the condyloid ridge; masseteric crest not curved upward anteriorly, but forms a nearly straight line from the base of the angular process ( fig. 7E–H View FIG ). Incisor enamel yellowish white, lowers tinged more orange than uppers; upper incisors opisthodont, robust, and strongly curved, with the base of the roots outside of, or level with, the maxillary base of the zygoma. Maxillary cheekteeth ( fig. 12E–G View FIG ) squarish to rectangular, with rounded posterior lophs and an uneven appearance due to unequal loph sizes. DP4–M3 always with two labial and two lingual flexi. Anterior lingual flexi (paraflexi) short, reaching only about half of the width of the tooth; the posterior lingual flexi (hypoflexi) longer; both labial flexi (para + hypoflexi) extend slightly more than half of the width of the tooth and are of the same length. DP4 and M1 always with a mure in the center of the tooth; M2–3 are with or without a mure, and all four flexi slant posteriorly from the edge to the middle of the tooth, so that labial and lingual flexi slant slightly in opposite directions. If without a mure, the joined flexi have a sharp elbow where the mure would be ( fig. 12G View FIG , arrow). Lower premolar usually divided by one central flexid into two V-shaped lophs, but with wear forms a midtooth mure. In m1–2 the lingual flexids are parallel and of about equal length. Flexids of all mandibular cheekteeth wide. Hypoconid with a flat labial profile ( fig. 12E–G View FIG ). Posterior borders of lower cheekteeth straight. Phallus of P. carrikeri   long and slender, with a long, pointed, bacular papilla, small urethral lappet, border of ventral crater wall a straight line without a U- or V-shaped ventral fold ( Emmons, 2005: fig. 10C View FIG ); those of other species are undescribed. Karyotypes of four specimens, which from their localities we assign to P. flavidus   and P. carrikeri   , were identical, 2 N = 94, among the highest found in Mammalia ( Aguilera et al., 1998)  .

COMPARISONS WITH OTHER GENERA: A white-speckled, spiny pelage is unique to the genus, although Leiuromys   , Mesomys   , Lonchothrix   , and Phyllomys pattoni   have strong, buff-tipped spines. There is no geographic overlap of these genera with Pattonomys   . The maxillary occlusal pattern of Pattonomys species   is unique for the family, and even single or worn upper teeth usually can be identified to genus. A quadralophodont lower premolar is shared only with Leiuromys   among Echimyini   , but in that genus, the mure is near the lingual edge of the upper molars, and the posterior edges of the lower cheekteeth are curved, while the mure of Pattonomys species   is near the center of the upper molars, and the posterior edges of the lower molars are straight. The flexids of Pattonomys   are wider than those of other Echimyini   . Likewise, the long, thin, simple phallus of P. carrikeri   is thus far unique among the Echimyini   ; those known for the other genera are short, thick, and with additional folds ( Leite, 2003; Emmons et al., 2005: fig. 10C View FIG ), but descriptions are needed for other species in every genus.