Part 11

=Proechimys longicaudatus boimensis= J. A. Allen

Proechimys boimensis Allen, 24 July, 1916, Bull. Amer. Mus. Nat. Hist., 35(27):523; 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.

Proechimys cayennensis Osgood, 1944, Zool. Ser. Field Mus. Nat. Hist., 29(13):199.

Type locality.--Boim, Rio Tapajoz, Santarem, Pará, Brazil. Type: American Museum of Natural History, no. 37486, adult male; "October 10, 1911 (ex Museu Goeldi)."

Range.--Along lower course of Tapajoz River.

Diagnosis.--Upper parts Ochraceous-Orange; incisive foramen posteriorly constricted; mesopterygoid fossa sharply pointed anteriorly; p4 with four counterfolds, remaining molariform teeth with three counterfolds.

Pelage.--Aristiforms on middorsal region: Gray basally, gradually blackening toward tip which is extended as a long filament; total length, 16 to 18 mm; maximum width, 0.5 mm. Setiforms on middorsal region: Gray basally, gradually blackening toward tip, but interrupted by short (1.5 mm), Ochraceous-Orange, subapical zone; total length 18 to 20 mm; maximum width 0.09 mm. Setiforms on outer thighs: White basally, gradually blackening toward tip but interrupted by Ochraceous-Orange, or Ochraceous-Buff, subapical zone 3.5 mm long; total length 15 to 17 mm; maximum width, 0.06 mm.

Skull.--Elongate and slender; rostrum slender and long; nasals evenly pointed posteriorly; supraorbital ridges weak and barely reaching anteriormost part of parietals; zygomatic arches slender; infraorbital foramen with groove for nerve-transmission obsolete; postorbital process of zygoma weak and involving mostly squamosal; incisive foramen 5 mm long and 2.5 to 3 mm wide, oval, with margins not much extended caudad as ridges; posterior margin of incisive foramen approximately 2 mm anterior to premolars; vomerine sheath complete with maxillary part slender; mesopterygoid fossa sharply pointed anteriorly and extending forward as far as anterior part of third molar; bullae of medium size, smooth and more or less triangular in contour.

Teeth.--Crown length of upper molariform teeth 7 to 7.5 mm; all upper molariform teeth with three counterfolds; lower premolar with four counterfolds; lower molars with three counterfolds each.

Comparisons.--From three of the other four subspecies found in Brazil, boimensis differs in having four, instead of three, counterfolds in the lower premolars. Differences from P. l. brevicauda are indicated in the account of that subspecies.

Remarks.--The material available from Boim, Tapajoz, is rather poor and of no great significance. The Museu Nacional has one specimen from Boim which agrees with the type in the American Museum of Natural History. The Museum of Comparative Zoology at Harvard College, however, has one specimen in its collection (MCZ no. 30888 ), adult, also from Boim, in which the color pattern is different although agreement with the type specimen is shown in cranial characters and width and length of hairs. This specimen is much darker than the other specimens (of orange-tint) assigned to this subspecies. However, in other samples of this species, similarly dark animals have been noted. It seems that the orange tint is gained only in old age. Another specimen (MCZ no. 30878 ) agrees in all respects with the type of the subspecies but the locality recorded on the label is Cametá, on the Tocantins River. Possibly the subspecies has a range so wide as to include Cametá but I suspect that the data on the label is incorrect as to locality. The collector marked on the label although the specimen is a . The mistake might have occurred through labeling of specimens at a time later than that at which they were collected. The collector was in both localities on more than one occasion.

Specimens examined.--Total number, 5, from Brazil, Pará, as follows: Santarem, Rio Tapajoz, Boim, 3 (AMNH type, MCZ 1, MN 1); Porto de Moz, Tauarí, 1 (MCZ); Cametá (?) 1 (MCZ).

=Proechimys longicaudatus longicaudatus= (Rengger)

Echimys longicaudatus Rengger, 1830, Naturgeschichte der Saeugethiere von Paraguay, p. 236.

Loncheres myosuros Lichtenstein, 1832, Darstellung neuer oder wenig bekannter Säugethiere, pl. 36 and text.

Echimys myosuros Is. Geoffroy Saint-Hilaire, 1840, Mag. Zool., Ann. 2 (ser. 2):15, 17; Allen, 1899, Bull. Amer. Mus. Nat. Hist., 12(20):261.

Echimys cayennensis Pictet, 1841, Mém. Soc. Phys. Hist. Nat., Genéve, 9:145; Waterhouse, 1848, Nat. Hist. Mammalia, 2:334.

Proechimys longicaudatus Thomas, 1901, Ann. Mag. Nat. Hist., 8 (ser. 7):532; Thomas, 1904, Proc. Zool. Soc. London, p. 240; Allen, 1916, Bull. Amer. Mus. Nat. Hist., 35(30):569; Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):400.

Proechimys cayennensis longicaudatus Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:121; Osgood, 1944, Zool. Ser. Field Mus. Nat. Hist, 29(13):198.

Type locality.--Northern Paraguay ("unter dem ein und zwansigsten Breitengrade"). Type: Apparently no type specimen was preserved.

Range.--Western Mato Grosso, Brazil, and northern Paraguay.

Diagnosis.--Upper parts almost uniformly Ochraceous-Buff; incisive foramen widest posteriorly; vomerine sheath complete; p4 and m2 with three counterfolds; m1 and m3 usually with two counterfolds.

Pelage.--Aristiforms on middorsal region: Dark gray, gradually blackening toward tip that has long filament; total length 20 to 22 mm; maximum width 0.6 mm. Setiforms on middorsal region: Whitish basally, gradually blackening toward tip but interrupted by Ochraceous-Buff, subapical zone; blackish tip extended (3.5 mm) and thin; total length 19 to 20 mm; maximum width 0.06 mm. Setiforms on outer thighs: Whitish basally, progressively grayish or blackish toward tip but interrupted by Light Ochraceous-Buff or Ochraceous-Buff, subapical zone; total length 18 to 20 mm; maximum width 0.06 mm.

Skull.--Slender; supraorbital ridge notably raised; bullae large, elongate, smooth and inflated; jugals narrow; postorbital process of zygoma of medium size and constructed entirely of jugal; incisive foramen wide and large (5.5 x 3 mm), being wider posteriorly than anteriorly and with posterior margins raised; vomerine sheath complete, maxillary part slender and laterally flattened; mesopterygoid fossa extending forward as far as centers, or anterior margins, of third molars; posterior palatine foramina on plane with posterior faces, or centers, of second molars.

Teeth.--Upper molariform teeth always with three counterfolds. Lower molariform teeth: p4 and m2 always with three counterfolds, sometimes the two anterior ones coalesced in m2; m1 with three counterfolds in one specimen (33 per cent); m3 with only two counterfolds in all specimens.

Comparisons.--Differences from P. l. leucomystax and P. l. roberti are given in the accounts of those subspecies.

Specimens examined.--Total number, 3 (2 AMNH, 1 CNHM), from Brazil, Mato Grosso, Corumbá, Urucum.

=Proechimys longicaudatus leucomystax= Ribeiro