Pattonomys carrikeri (J.A. Allen, 1911 )

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 : 31-32

Pattonomys carrikeri (J.A. Allen, 1911)

Loncheres carrikeri J.A. Allen, 1911: 251 (original description).

TYPE SPECIMEN AND TYPE LOCALITY: The holotype (by original designation, AMNH 31530 ) consists of the skin and skull of an adult female collected by M.A. Carriker, Jr., on 15 November 1910 at “San Esteban,” Carabobo, Venezuela .

DIAGNOSIS AND DESCRIPTION: Similar externally to Pattonomys punctatus , but smaller and upperparts usually paler and laterally more yellowish tinged ( tables 5, 6); dorsal midbody between limbs washed dull rusty from long, rust-orange tipped setiforms among the spines. Scattered whitetipped aristiforms start to appear behind the shoulder and increase posteriorly. Underparts whitish gray either sharply demarcated from sides, or grading gradually, with hairs pale gray based and white tipped; midline, chest, and inguinal area nearly white. Head in front of ears, forelimbs, and tops of feet grizzled slate gray, frosted with white-tipped hairs. Postauricular pale patches inconspicuous, gray. Tail hairs blackish above, paler below. We examined the feet of fluid-fixed specimens of this species only (N = 16): hind feet with small, indistinct plantar tubercles between the pads; digital pads 1 and 2 elongate, narrow ovals or semicircles; a small auxiliary pad lateral to digital pad 4 always present ( fig. 6B ). Incisors white and slightly opisthodont; maxillary molar toothrows straight and parallel. Cranium moderately robust, with zygomatic arches usually bowed outward. Supraorbital shelves wide and curved upward. Unique in the genus, basicranium with a single, joined masticatory and buccinator foramen ( fig. 15B ). Palatal notch narrow, with straight sides and a narrow canal. Auditory tympanic bullae distinctly inflated and rounded anteroventrally ( figs. 7G , 10G ).

GEOGRAPHIC RANGE AND HABITAT: Northern Venezuelan lowlands (fig. 1) from about Apure and Falcón east to Caracas and south to Guárico (Zaraza). Collected in trees and from tree hollows near water sources, usually in thorn forest or isolated trees in savanna; in a general region of savannas, arid scrub, and cactus ( Allen, 1911; Tate, 1935; Handley, 1976).

REMARKS: This species is represented by many specimens in collections, and there is much variation in color pattern of the underparts within series of specimens from the same locality. The original description states it to be much darker than P. punctatus , with blackish middorsum, but this coloration does not seem to be found in specimens seen by us. However, Allen (1911), as we did, noted the more inflated bullae and markedly narrower palatal notch (“posterior nares”) of P. carrikeri compared to those of P. punctatus . We have not dissected the basicranial region and what we call the “joined” maxillary and buccinator foramina is present as a single wide foramen positioned laterally at the site of the buccinator ( fig. 15B ). We follow the nomenclature of Wahlert (1974: 370, fig. 1) in classing them as joined, but instead the masticatory foramen may simply be lacking and the associated artery passed internally through the alisphenoid canal.

SPECIMENS EXAMINED: VENEZUELA: Carabobo, San Esteban (AMNH 31530); Montalbán, 1.2 km SE Montalbán, El Castaño, (USNM 442715); Falcón, Urama, 19 km NW Urama, km 40, (USNM 372701); Lara, Río Tocuyo, (AMNH 130790–130814, 131087); 10 km N El Tocuyo, Caseria Boro, (USNM 456429, 456430, 456433–456437, 456439, 456440, 456443, 456444*, 496483, 496485, 496487–496490, 496492, 496494–496496, 496500–496506, 496508, 496509); San Miguel, San Gerónimo, (AMNH 132836–132844, 132846); San Miguel, Hacienda La Fortuna, (AMNH 132849–132859); San Rafael (AMNH 132845, 132847); Distrito Federal, Caracas, (AMNH 130815); Guárico, Zaraza, (AMNH 135442, 135443, 135471, USNM 314996); Río Orituco, 10 km W of Chaguaramas, (ROM 107955*).

Figures

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. 15. Pattonomys basicrania. A, Pattonomys punctatus USNM 374741; B, P. carrikeri USNM 456429. Note separate masticatory and buccinator foramina (arrows), robust extra bony rings below meatus, wide mesopterygoid fossa, and less inflated auditory tympanic bullae in A; joined foramina and more inflated bullae in B.

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.

FIG. 10. Crania, palatal 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.