Proechimys albispinus albispinus [Thomas], 1921, Ann. Mag. Nat. Hist., 8 (ser. 9):141; [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.—Ilha Madre de Deus, Itaparica (near Salvador), Bahia, Brazil. Type: Museum d'Histoire Naturelle, Paris, no. A 7669, "skull ... practically perfect" ([Thomas], 1921:142).
Range.—Island Madre de Deus, Macaco Seco, Andaraí and probably islands of the bay of Todos os Santos and valley of the Paraguassú River.
Diagnosis.—Aristiforms wide; color on setiforms Ochraceous-Tawny on upper parts and sides; incisors orthodont; molariform teeth with one counterfold, p4 rarely with two.
Pelage.—Aristiforms on middorsal region: Lanceolate aristiforms, with basal part whitish, gradually blackening toward tip; total length, 25 to 28 mm; maximum width, 1.2 mm; clavate aristiforms with base whitish, gradually blackening toward tip but interrupted by Ochraceous-Tawny, subapical zone. Aristiforms on outer thighs: Whitish on basal half, gradually blackening toward tip; total length, 24 to 26 mm; maximum width, 0.9 mm. Some are whitish basally, gradually blackening toward distal part but distal fourth or fifth near (15'j) Ochraceous-Tawny. Setiforms on middorsal region: Whitish basally, gradually blackening toward tip but interrupted by Ochraceous-Tawny, subapical zone; total length, 20 to 23 mm; maximum width, 0.1 mm. Some setiforms almost completely whitish. Setiforms on outer thighs: Whitish basally, gradually blackening toward tip but interrupted by near (15'j) Ochraceous-Tawny, subapical zone; total length, 18 to 20 mm; maximum width, 0.06 mm.
Skull.—Narrow; bullae small and smooth; jugals dorso-ventrally wide with conspicuous transverse ridge; postorbital process of zygoma well-developed and formed by jugal and squamosal; posterior palatine foramina obsolete; incisive foramen narrow and short; vomerine sheath complete or incomplete but premaxillary part at a level lower than that of maxillary part (when skull is viewed from ventral face); mesopterygoid fossa extending forward as far as anterior borders of second molars.
Teeth.—Incisors orthodont; molariform teeth with only one counterfold, except that p4 rarely has two counterfolds.
Comparisons.—From P. a. sertonius, albispinus differs in: sides of body darker; incisors orthodont as opposed to proodont; p4 rarely with two counterfolds instead of always with one counterfold.
Remarks.—The localities where P. a. albispinus has been collected have a forest climax with a moderate percentage of deciduous trees.