Toromys grandis ( Wagner, 1845 )

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 : 35-37

Toromys grandis ( Wagner, 1845)

Loncheres grandis Wagner, 1845: 146 (original description).

TYPE SPECIMEN AND TYPE LOCALITY: NMW 920 ; a skin with missing distal tail and skull without rostrum, sex unknown but probably male; collected by J. Natterer ( JN 167 ) in “Amazonstrom,”

5 DNA sequenced to confirm identity. this locality given by Pelzeln (1883: 63) as “Manaqueri im Mündungsbereich des Rio Solimões,” now Manaquiri ( Paynter and Traylor, 1991). Pelzeln also noted, from Natterer’s catalogue, that the specimen was received from Estanislao stuffed and unfortunately missing the tail tip.

DIAGNOSIS AND DESCRIPTION: The largest of the Echimyini (head and body length 275– 254 mm; greatest length of skull 67–70 mm; tables 5, 6). Dorsal pelage a striking mixture of pitch black and ochraceous yellow-banded aristiform bristles that impart a golden or warm ochraceous-yellow appearance at the midbody ( fig. 14A ). Head, crown, and neck black speckled with a few yellow-banded hairs. Underparts gray, with dark gray-based hairs tipped with translucent cream; the inguinal region tends to be cream colored. The dorsal color grades gradually into the ventral color field. Tail robust, generally about the same as head-and-body length, thickly haired at the base above and below with an extension of dorsal pelage onto tail; tail pelage changes abruptly to long, dense, straight, pitch-black hairs that nearly cover scales and are longest near tail base to form a puff on the basal third ( fig. 14A ). Rare specimens have the extreme tail tip whitish, but not tufted. Hind feet broad at the base of the toes and narrow at the heel ( fig. 14A ); blackish above, finely speckled with yellow, with black toes; ungual tufts sparse and shorter than the robust claws; palmar surfaces are pinkish, but otherwise as described for T. rhipidurus ( fig. 6A ). Cranium narrow and elongate in dorsal view, with a narrow rostrum, nasals distally flared laterally and slightly pinched-in medially; medial parietal-interparietal suture recurved anteriorly between the separated temporal ridges (insertions of the posterior temporalis, 33/35 crania), which are raised in older individuals ( fig. 9A , black arrow), or more rarely, the suture is nearly straight (2/35); squamosal expanded laterally into a broad shelf over the meatus (the insertion of the pars posterior of the temporalis muscle), such that the skull is much wider over the ear than at its narrower point posterior to the tip of the jugal ( fig. 9A , white arrow). In dorsal view, the zygomatic arches generally narrow anteriorly. In lateral view, jugal robust and deep dorsoventrally; and squamosal forms a strong beaded ridge over the auditory meatus ( fig. 7A ). Upper incisors orange faced and extremely robust, with roots within the anterior maxillary base of the zygoma (posterior to a vertical line drawn from the anterior edge of the ascending arch). Many characters were reported in Iack-Ximenes et al. (2005), but others are first noted here.

NATURAL HISTORY: Toromys grandis appears to be restricted to seasonally or permanently flooded forests of várzea (white water) and igapó (black water) rivers. The BBC film “Amazon, Land of the Flooded Forest” shows two T. grandis using a treehole and traveling with monkeylike agility along branches in flooded forest (but it might have been filmed ex situ). Abreu- Júnior et al. (2017) twice saw T. grandis jump into the water and swim beneath the surface to escape when approached. Toromys grandis descends to terrestrial riverbanks, perhaps for mineral nutrients ( fig. 14A ), as does Echimys saturnus (see Blake et al., 2010). A recent image shows T. grandis feeding on green, unripe fruit of Gustavia sp. (Lecythidaceae) along the Rio Maués- Mirim about 70 km S of Urucurituba (fig. 1: loc. 16; J. Hall, personal commun.), and F. Reid (personal commun.) saw T. grandis feed on both leaves of a leguminous tree, and fruits. The large body size, robust cranium, and tendency in Toromys toward near-laminarity of the upper cheekteeth may be associated with a herbivorous or fibrous diet, as might the lateral expansion of the squamosal attachment of the temporalis muscle of T. grandis ( fig. 9A ), which is similarly expanded in the herbivorous “dactylomyines.”

SPECIMENS EXAMINED: BRAZIL: Amazonas, Lago Manaquiri ( NMW 920 [holotype]) ; Villa Bella Imperatriz (= Parantins), Santa Clara, Amazon River , south bank, ( AMNH 92907 , 92909– 92950 , 93151–93153 , 93594–93624 , 93785 , 93786 ) ; Serra do Parintins, Amazon River , south bank (not located); ( AMNH 93625–93633 , 94020–94036 ) ; Boca do Igarapé Piaba ( MCZ 32352, 32353 ) ; Paraná de Faro, ( BMNH 11.12.22.12) ; Santarém, ( BMNH 5.6.3.1) ; Rio Amazonas, Ilha Urucurituba ( FMNH 92198 *, 92199) ; Pará, Faro, Fazenda Paraiso , ( AMNH 37476 ) ; Faro , ( AMNH 94037–94043 ) ; Villarinho do Monte, Rio Xingu , ( AMNH 95957 ) ; Faro, Amazon River, north bank, Nhamundá River , Lago Uaimy , ( AMNH 94193 , 94194 ) ; Rio Nhamundá, Fazenda Paraiso , ( FMNH 19497 ) .

Figures

FIG. 14. Living Toromys and Pattonomys. A, Toromys grandis, lower Rio Purus, (fig. 1, locality 31). Note the elongate body, the longer black hair on the proximal tail, and the broad foot with narrow heel. There is a postauricular patch of pale skin. The anterior bright eyeshine spot seems to show an oval, vertical pupil, the other spot is a reflection of the flash (image by Vinicius Carvalho). B, Pattonomys semivillosus in a black mangrove tree (Avicennia germinans) in Parque Nacional Isla de Salamanca, Magdalena, Colombia. The white postauricular tufts above and behind the ear are striking (photograph by Fabrice Schmitt). C, Toromys rhipidurus, captured near Iquitos, Peru. The evident cream-colored postauricular patches are not visible on most museum skins. The camera-flash has accentuated the yellow midbody hues (image by Pamela Sánchez-Vendizú).

FIG. 6. Variation among genera in plantar surfaces of hindfeet, fluid-preserved specimens. A, Toromys rhipidurus AMNH 276710; B, Pattonomys carrikeri USNM 496501; C, Phyllomys pattoni, UFES 121; D, Makalata cf. didelphoides USNM 581981 (Bolivia); E, M. cf. macrura USNM 496480 (Venezuela); F, Echimys chrysurus, USNM 549839 (Rio Xingu). Note small digital pads, especially D3, and collars of small tubercles around pads in (A–C); large digital pads and no collars of tubercles in (D–F); merged D1 and thenar pad in (E–F), leaving three separated digital pads; and differences in digital pad shapes (see text). Abbreviations: D, digital pads; Th, thenar pad; Hy, hypothenar pad. Arrow in A indicates supernumerary separated pad of Pattonomys spp. Figures not to scale. Photo panel C, Yuri Leite.

FIG. 9. Crania, dorsal view. A, Toromys grandis AMNH 93601; B, T. rhipidurus BMNH 28.7.21.89 (holotype); C, T. sp. nov., FMNH 55483 (holotype), D, Leiuromys occasius. AMNH 71897; E, Pattonomys punctatus BMNH 98.12.1.18 (holotype); F, P. flavidus USNM 63218 (holotype); G, P. carrikeri AMNH 130790; H, P. semivillosus USNM 280205. Black arrow in A indicates recurved parietal-interparietal suture, white arrow the expanded squamosal shelf.

FIG. 7. Crania and mandibles, lateral view. A, Toromys grandis AMNH 93601; B, T. rhipidurus BMNH 28.7.21.89 (holotype); C, T. sp. nov., FMNH 55483 (holotype), D, Leiuromys occasius. AMNH 71897; E, Pattonomys punctatus BMNH 98.12.1.18 (holotype); F, P. flavidus USNM 63218 (holotype); G, P. carrikeri AMNH 130790; H, P. semivillosus USNM 280205. Black arrow in F indicates the deep mandible of P. flavidus relative to its congeners.