Part 12

Proechimys leucomystax Ribeiro, May, 1914, Commissão de linhas telegraphicas estrategicas de Matto Grosso ao Amazonas, Annexo no. 5. Hit. Nat., Zool., Mammiferos, p. 42, pl. 24 (orig. descr.); Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):400; Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:119.

Type locality.--Utiarití, Rio Papagaio, Diamantion, Mato Grosso, Brazil. Type: Museu Nacional, no. 2212, adult, skull only, collected on 5 May 1909, by Prof. A. Miaranda Ribeiro, is here designated lectotype. See remarks.

Range.--Serra dos Parecís, Mato Grosso, Brazil.

Diagnosis.--Ochraceous-Buff, richly lined with blackish, on upper parts; some setiforms completely blackened distally; incisive foramen regularly ovoid; vomerine sheath incomplete; upper molariform teeth and lower premolar with three counterfolds; m2 with three counterfolds but m1 and m3 usually with two counterfolds.

Pelage.--Aristiforms on middorsal region: Grayish basally, gradually blackening toward tip which is extended as a long filament; total length 21 to 22 mm; maximum width 0.65 mm. Setiforms on middorsal region: Whitish basally, gradually blackening toward tip but interrupted by Ochraceous-Buff, subapical zone; some setiforms grayish basally and gradually blackening toward distal portion without any colored, subapical zone; total length 20 to 22 mm, maximum width 0.06 mm. Setiforms on outer thigh: White basally, gradually becoming gray toward tip but interrupted by Light Ochraceous-Buff, subapical zone; some setiforms gray basally and blackening toward tip, but interrupted by Ochraceous-Buff, subapical zone; total length 15 to 18 mm; maximum width 0.08 mm.

Skull.--Slender; supraorbital ridges conspicuous; bullae large, smooth and inflated, with slight, transverse groove; jugals narrow; postorbital processes of zygomata small and involving only squamosal; incisive foramen of medium size but narrow (5 x 2.5 mm), regularly oval and with margins uplifted posteriorly; vomerine sheath incomplete but maxillary part projecting forward and sometimes almost reaching premaxillary part; mesopterygoid fossa reaching forward as far as centers of third molars; posterior palatine foramina at plane of posterior faces of second molars or slightly anterior thereto.

Teeth.--Upper molariform teeth with three counterfolds. Lower molariform teeth: p4 and m2 always with 3 counterfolds; m1 and m3 with 2 counterfolds.

Comparisons.--From P. l. longicaudatus, leucomystax differs in: upper parts richly lined, instead of scarcely lined, with blackish; incisive foramen narrower, and regularly oval instead of widest anteriorly.

Remarks.--Proechimys leucomystax was described mainly on the basis of the Utiarití specimen, here designated lectotype of the species. The specimen from the Juina River is younger, as stated by Ribeiro in his description. Ribeiro mentions the skin of the specimen from Utiarití as "em muito mao estado" and I presume it was discarded as it has not been found in the collection of the Museu Nacional, Brazil.

Specimens examined.--Total number, 6, from Brazil, Mato Grosso: Cáceres, Salto Sepotube, 2 (MN); Cáceres, Tapirapoã, Rio Sepotuba, 2 (AMNH); Diamantino, Utiarití, Rio Papagaio, 1 skull (MN); Diamantino, Rio Juina, 1 (MN).

=Proechimys longicaudatus roberti= Thomas

Proechimys roberti Thomas, December, 1901, Ann. Mag. Nat. Hist., 8 (ser. 7):531 (orig. descr.); Thomas, 1904, Ann. Mag. Nat. Hist., 14 (ser. 7):195; Thomas, 1921, Ann. Mag. Nat. Hist., 8 (ser. 9):140; Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):400.

Proechimys cayennensis roberti Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:121.

Type locality.--Rio Jordão, Araguarí, Minas Gerais, Brazil; 960 meters alt. Type: British Museum (Nat. Hist.), no. 1.11.3.62, old male, collected 8 August, 1902, by A. Robert; original number, 705.

Range.--Western Minas Gerais and southern Goiaz.

Diagnosis.--Color almost uniformly Ochraceous-Orange on upper parts; setiforms long and narrow; incisive foramen long and wide; vomerine sheath usually complete; upper molariform teeth and lower premolar with three counterfolds; m3 with two, and m1 and m2 with two or three, counterfolds.

Pelage.--Aristiforms on middorsal region: Whitish basally, gradually blackening toward tip; total length, 21 to 23 mm; maximum width, 0.6 mm. Setiforms on middorsal region: Whitish on basal half, gradually blackening toward tip but interrupted by an Ochraceous-Orange, subapical zone 6 to 7 mm long; total length 25 to 30 mm; maximum width, 0.05 mm. Setiforms on outer thighs: Whitish on basal half, gradually becoming gray and then blackish toward tip but interrupted by wide, Ochraceous-Buff, subapical zone, the tip being brownish or blackish; total length, 22 to 23 mm; maximum width, 0.04 mm.

Skull.--Slender; supraorbital ridges bent outward and making sharp angle at point of frontosquamosal suture, then continuing backward parallel to each other and extending across parietals; squamosal taking small part in supraorbital ridges; bullae large (11 x 8 mm), inflated, with shallow depressions; incisive foramen not especially long but wide (5 x 3 to 3.5 mm), widest in anterior third and constricted posteriorly; vomerine sheath usually complete, with maxillary part reduced to slender threadlike process or, less commonly, missing; mesopterygoid fossa extending forward as far as centers of third molars; zygomatic arches strong with jugals of medium dorsoventral width (approximately 3.5 mm); postorbital process of zygoma weakly developed and involving only squamosal; posterior palatine foramina on plane of posterior margins of first molars or slightly anterior thereto.

Teeth.--Upper molariform teeth usually with three counterfolds (92.5 per cent of 42 specimens); M2 with four counterfolds in 5 per cent of specimens; M3 with two counterfolds in 2.5 per cent of specimens. Lower molariform teeth: p4 usually with three counterfolds (97.5 per cent of 39 specimens); rarely with four (2.5 per cent); m1 with three counterfolds in 58 per cent and two counterfolds in 42 per cent of specimens; m2 with three counterfolds in 61 per cent and two counterfolds in 39 per cent of specimens; m3 always with only two counterfolds.

Comparisons.--From P. l. boimensis, roberti differs in: wider incisive foramen; lower premolar with three, and one or two lower molars with only two, counterfolds, instead of lower premolar with four and all lower molars with three counterfolds. From P. longicaudatus, roberti differs in: upper parts Ochraceous-Orange instead of Ochraceous-Buff; incisive foramen wider in posterior third than in anterior third.

Remarks.--This subspecies seems to be adapted to forests of post-climactic conditions which is probably typical of most valleys and margins of the rivers in southern Goiaz and western Minas Gerais. It was found in Goiaz usually in riparian forests with climactic associations or in some advanced stage of the sere. The animals also make incursions into nearby open areas or crops of corn.

Specimens examined.--Total number, 52, from Brazil, as follows: Minas Gerais, Araguarí, Rio Jordão (effluent of Parnaiba), 960 meters alt., 2 (1 CNHM, 1 DZ); Goiaz, Anapolis, 1010 meters alt., 38 (MN); Goiaz, Pouso Alto, 768 meters alt., 11 (MN); Goiaz, Tio São Miguel, 2 (MN).

=Proechimys guyannensis= (E. Geoffroy)

Mus guyannensis E. Geoffroy Saint-Hilaire, 1803, Catalogue des mammifères du Museum d'Histoire Naturelle, Paris, p. 194.

Echimys cayennensis Desmarest, 1817, Nouv. Dict. Hist. Nat., Paris, nouv. ed., 10:59.

Proechimys cayennensis Allen, 1899, Bull. Amer. Mus. Nat. Hist., 12(20):261, 264; Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):399; Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:120.

General characters.--Size medium to large; tail usually short; aristiforms narrow to wide; general color of setiforms on back ranging from Tawny to Ochraceous-Buff and becoming gradually lighter on sides; no conspicuous dark longitudinal band on back; upper parts of hands and feet white to light brown; underparts white, including inner sides of legs; skull elongate and not conspicuously ridged; vomerine sheath complete or incomplete; upper premolar with three counterfolds and molars with two or three; lower premolar with three or four counterfolds, and lower molars with two or three.

=Proechimys guyannensis villicauda= subspecies nova