Part 13

Marginal records.--MORELOS: 5 mi, W Tepoztlan, 6000 ft. PUEBLA: 2 mi. S Atlixco, 5800 ft.; Acatlan, 4100 ft. OAXACA: 2 mi. NW Tamazulapan, 6550 ft; Tepantepec; Oaxaca , 5000 ft; Yalalag, 3000 ft; Jalapa, El Campanario; Reforma; Huilotepec; 3 mi. S Candelaria; Cerro Otate; Pinotepa, 700 ft. GUERRERO: Acapulco; Zihuatanejo Bay; El Limon; 9 mi. SE Taxco, 3800 ft.

U. S. Nat. Museum (Biol. Surv. Coll.).

Univ. Michigan, Museum of Zoology.

Texas A & M, Cooperative Wildlife Research Collection.

Chicago Natural History Museum.

California Academy of Sciences.

American Museum of Natural History.

University of Florida Collections.

=Baiomys musculus pullus= Packard

Baiomys musculus pullus Packard, Univ. Kansas Publs., Mus. Nat. Hist., 9:401, December 19, 1958.

Baiomys musculus grisescens, Goodwin, Bull. Amer. Mus. Nat. Hist., 79(2):161, May 29, 1942 (part); Miller and Kellogg, Bull. U. S. Nat. Mus., 205:513, March 3, 1955 (part); Hall and Kelson, The Mammals of North America, 2:661, March 31, 1959 (part).

Type.--Adult female, skin and skull; No. 71605 University of Kansas Museum of Natural History; 8 mi. S Condega, Esteli, Nicaragua, obtained on July 15, 1956, by A. A. Alcorn, original number 4218.

Range.--West-central Nicaragua, from Matagalpa northwest into the valley of the Rio Esteli, east as far as Jinotega, see Figure 10. Zonal range: Upper Tropical Life-zone.

Diagnosis.--Size medium to small for the species; dorsum Fuscous-Black, individual hairs black-tipped with a subterminal band of Ochraceous-Buff, Neutral Gray at base; some hairs on dorsum all black to Neutral Gray at base; hair on sides Neutral Gray tinged with blackish; face blackish, becoming buffy on sides of head, and white on throat; vibrissae black; tail unicolored Chaetura Black; forefeet and hind feet sooty to dusky-white; mid-ventral region of venter white, hairs white to base; in region of anus and throat, hairs white-tipped, Neutral Gray at base; average and extreme external and cranial measurements of the type and 16 paratypes are as follows: total length, 117.3 (111-121); length of tail vertebrae, 47.2 (44-50); length of body, 70.4 (66-74); length of hind foot, 15.5 (14-17); length of ear from notch, 11.9 (10-13); occipitonasal length, 19.3 (18.9-19.8); zygomatic breadth, 10.2 (9.7-10.6); postpalatal length, 7.0 (6.8-7.3); least interorbital breadth, 3.9 (3.8-4.1); length of incisive foramina, 4.3 (4.0-4.6); length of rostrum, 7.0 (6.5-7.4); breadth of braincase, 9.6 (9.3-10.0); depth of cranium, 7.0 (6.8-7.3); alveolar length of maxillary tooth-row, 3.1 (3.0-3.2); for photographs of skull, see Plate 1h, and Plate 3h.

Comparisons.--From B. m. grisescens, B. m. pullus differs in: dorsum and tail darker; sides and lateral parts of venter grayish instead of buffy-brown, thus forming distinct mid-ventral white stripe; average length of body and tail significantly longer, thus total length greater; maxillary tooth-row significantly shorter; slightly larger in other cranial and external dimensions.

From B. m. nigrescens, B. m. pullus differs in: dorsum slightly darker; face grayish, not sooty; mid-ventral white stripe (absent in most specimens of nigrescens) present and becoming grayish laterally; tail darker, less hairy, and averaging significantly longer; smaller in most external and cranial dimensions.

Remarks.--B. m. pullus resembles B. m. nigrescens in size and color but can readily be distinguished from nigrescens by the shorter tail. B. m. pullus intergrades with nigrescens as shown by specimens, referable to B. m. nigrescens, from 1 mi. NW San Salvador and from 1 mi. S Los Planes, El Salvador. In color of the dorsum, specimens from these localities are intermediate between nigrescens and pullus.

The mid-ventral white stripe characteristic of pullus is present in three of 28 adults from El Salvador. Goodwin (1942:160) reported white hairs on the pectoral region of several topotypes of B. m. grisescens. The areas of white hairs on the venter of grisescens occur in approximately 10 per cent of the specimens examined, whereas in pullus, the frequency of occurrence is 90 per cent. The areas of white hairs in grisescens are in broad patches on the pectoral region, while in pullus, a white stripe passes from the pectoral region to the inguinal region in both males and females. I know of no selective advantage that the presence of this white stripe would confer on the mice.

Specimens examined.--Total 46, all from NICARAGUA, and distributed as follows: Type locality, 32 (including the type); 9 mi. NNW Esteli, 8; 8 mi. NNW Esteli, 3; San Rafael Del Norte, 1 (Amer. Mus. Nat. Hist.); 1 mi. NW Jinotega, 1; Matagalpa, 1 (Amer. Mus. Nat. Hist.).

Marginal records.--NICARAGUA: San Rafael Del Norte; Matagalpa; type locality.

=Baiomys taylori=

Northern Pygmy Mouse

(Synonymy under subspecies)

Type.--Hesperomys (Vesperimus) taylori Thomas, Ann. Mag. Nat. Hist., Ser. 5, 19:66, January, 1887.

Range.--Southeastern Arizona and southwestern New Mexico, south into Chihuahua and Durango, just east of the Sierra Madre Occidental, thence southeast through Zacatecas, Aquascalientes, Jalisco, Queretaro, and Guanajuato; two fingerlike projections extend northward, one on the west along the coast of Sinaloa into southern Sonora, and the other on the east covering eastern San Luis Potosi, Tamaulipas, eastern Coahuila, Nuevo Leon, into south, southeast, and north-central Texas. Southern margin of range in central Mexico approximates the 19th degree of latitude (see Figure 11). Arid lower and arid upper subdivisions of the Tropical Life-zone in south; principally Lower Sonoran and Lower Austral life-zones in north.

Characters for ready recognition.--Unless otherwise noted, characters are usable for the age-categories of adult and old adult. Differs from B. musculus in: hind foot less than 16 millimeters; occipitonasal length less than 19 millimeters; zygomatic breadth less than 10 millimeters; rostrum deflected ventrally at frontoparietal suture rather than curving gradually toward anteriormost point of nasals; cingular ridges and secondary cusps on teeth reduced or absent; basihyal having entoglossal process much reduced or absent, shoulders of basihyal not protruding anteriorly, but more flattened (characteristic of all age categories); baculum having narrower shaft, knob-shaped tip, wings at base projecting laterally, baculum less than 3 millimeters long; short process of incus attenuate; muscular process of posterior crus of stapes reduced.

Characters of the species.--Size small (extremes in external measurements of adults: total length, 87-123; length of tail vertebrae, 34-53; length of hind foot, 12-15; length of ear, 9-12). Upper parts pale drab or reddish-brown to almost black; underparts grayish to cream-buff.

Geographic variation.--Eight subspecies are here recognized (see Figure 11). Features that vary geographically are mostly the same as those that do so in B. musculus (see page 609).