Specimens examined.—Total number, 19 (18 CMNH, 1 MCZ), from Brazil, Bahia, Andaraí, Macaco Seco.
Proechimys albispinus sertonius [Thomas]
Proechimys albispinus sertonius [Thomas], July, 1921, Ann. Mag. Nat. Hist., 8 (ser. 9):142 (orig. descr.); [Tate], 1935, Bull. Amer. Mus. Nat. Hist., 68(5):401; [Ellerman], 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:122.
Type locality.—Lamarão ("about 70 miles north of Bahia City"), Ituiutaba, Bahia, Brazil; altitude 300 meters. Type: British Museum (Nat. Hist.), no. 3.9.5.86, adult male; collected on 16 June, 1903, by Alphonse Robert; original number, 1508.
Range.—Known from the type locality and Bonfim; probably occupies valleys of Jacuipe and the Itapicurú rivers and littoral between them.
Diagnosis.—Aristiforms wide; color of setiforms Ochraceous-Tawny on back, grading to Ochraceous-Buff on sides; incisors proodont; no molariform tooth with more than one counterfold.
Pelage.—Aristiforms on middorsal region: Lanceolate aristiforms whitish basally, gradually blackening toward tip; total length, 23 to 27 mm; maximum width, 1.3 mm. Clavate aristiforms, and some lanceolate ones, whitish basally, gradually blackening toward tip but interrupted by Ochraceous-Tawny, subapical zone. Some clavate aristiforms without subapical zone but blackened in distal part; total length, 23 to 24 mm; maximum width, 0.7 mm. Aristiforms on outer thighs: Whitish basally, gradually blackening toward tip but interrupted by Light Ochraceous-Buff, subapical zone; tip slightly darker; some whitish basally, grayish in middle and light yellowish toward tip; total length, 20 to 22 mm; maximum width, 0.9 mm. Setiforms on middorsal region: Whitish basal part succeeded by grayish, then by long, light, yellowish band, which becomes Light Ochraceous-Buff, and blackish tip; total length, 26 to 29 mm; maximum width, 0.15 mm. Setiforms on outer thighs: Whitish basal part succeeded by grayish, then Light Ochraceous-Buff, subapical zone and blackish tip; total length, 18 to 20 mm; maximum width, 0.13 mm.
Skull.—Broad; bullae small and smooth; jugals dorso-ventrally "wide," with conspicuous transverse ridge; postorbital process of zygoma well-developed and formed by both jugal and squamosal; incisive foramen narrow and short; vomerine sheath incomplete or complete but premaxillary part on a lower level than maxillary part (when skull is viewed from ventral face); mesopterygoid fossa extending forward as far as anterior faces of second molars.
Teeth.—Incisors proodont; molariform teeth with only one counterfold.
Comparisons.—Differences from P. a. albispinus are given in the account of that subspecies.