Peromyscus polionotus (Wagner 1843)

Mus polionotus Wagner, 1843:52 .

Hesperomys niveiventris (Chapman), 1889:18 .

Sitomys niveiventris subgriseus Chapman, 1893:341 .

Peromyscus phasma subgriseus Bangs, 1898c:199 .

Peromyscus subgriseus subgriseus Bangs, 1898c:200 .

Peromyscus subgriseus rhoadsi Bangs, 1898c:201 .

Peromyscus subgriseus arenarus Bangs, 1898c:202-203 .

Peromyscus subgriseus baliolus Bangs, 1898c:214-215 .

Peromyscus polionotus Osgood, 1907:49 .

Peromyscus polionotus niveiventris Osgood, 1909:105 .

Peromyscus polionotus phasma Osgood, 1909:107 .

Peromyscus polionotus rhoadsi Osgood, 1909:107 .

Peromyscus polionotus albifrons Osgood, 1909:108 .

Peromyscus polionotus leucophalus A. H. Howell, 1920:239 .

Peromyscus polionotus decoloratus A. H. Howell, 1939:363 .

Peromyscus polionotus peninsularis A. H. Howell, 1939:364 .

P[eromyscus]. p[olionotus].subgriseus Schwartz, 1954:562 .

Peromyscus polionotus lucubrans Schwartz, 1954:564 .

Peromyscus polionotus colemani Schwartz, 1954:566 .

Peromyscus polionotus ammobates Bowen, 1968:16 .

Peromyscus polionotus griseobaracatus Bowen, 1968:16 .

Peromyscus polionotus trissyllepsis Bowen, 1968:17 .

Peromyscus polionotus allophrys Bowen, 1968:18 .

Peromyscus polionotus sumneri Bowen, 1968:20 .

Holotype.— Osgood (1909) examined the type specimen (catalog number) on exhibit at the museum of the Polytechnic in Zurich. Skull and tail vertebrae were still in the specimen. The specimen initially was identified by Wagner (1843) as Mus polionotus, from somewhere in Georgia, United States. Osgood noted the identity of the specimen was most probably assignable to P. p. subgriseus .

Type locality.— Little information is available for determination of the type locality of P. polionotus . As researched and reviewed by Osgood (1909), it appears that Georgia, United States may be as precise a locality as is possible to determine.

Subspecies.— Hall (1981) recognized the following 16 subspecies: P. p. albifrons, P. p. allophrys, P. p. ammobates, P. p. colemani, P. p. decoloratus, P. p. griseobaracatus, P. p. leucophalus, P. p. lucubrans, P. p. niveiventris, P. p. peninsularis, P. p. phasma, P. p. polionotus, P. p. rhoadsi, P. p. subgriseus, P. p. sumneri, and P. p. trissyllepsis.

Diagnosis.— Size is very small for the species group (Osgood 1909). External measurements obtained from Osgood (1909), for several of the subspecies now assigned to P. polionotus, indicated a total length that ranged between 125–137 mm; (= 131 mm) and a tail length that ranged between 41–52 mm; (= 46.5 mm). Dorsal pelage is gray along back and shoulders with sides containing a mixture of gray and light cinnamon coloration. Tail is short and bicolored.

Distribution.— This species is restricted to the southeastern United States and ranges from northeastern Mississippi to western South Carolina, southward through Alabama and Georgia to central Florida (Osgood 1909).

Comparisons.— A member of the P. maniculatus species group. With the exception of slightly larger auditory bullae the skull is much smaller than other members of the genus and most closely resembles that of P. maniculatus (Osgood 1909; Hall 1981).

Cyt b sequences (this study) indicated that P. polionotus differs from P. maniculatus (sensu stricto) and P. sonoriensis by 5.12% and 4.71% respectively. Genetic differentiation (= 0.50%) based on DNA sequences obtained from 13 individuals of P. polionotus indicated the lowest level of genetic divergence for members of the P. maniculatus species group. The small geographic distribution of this species may explain this observation.

Remarks.— Thirteen samples were examined in this study that are assignable to P. polionotus . Of these samples, all were from Florida, given that the type locality is unknown we could not estimate the relative proximity; however, given that no other P. maniculatus species occurs in this area we assume these samples are good representatives of P. polionotus .

Although the karyotype of P. polionotus (FN = 69–71; Te and Dawson 1971) is unique relative to those of other species in the P. maniculatus group, several synapomorphies place it in this group (Robbins and Baker 1981; Stangl and Baker 1984). However, determining the phylogenetic association of P. polionotus to other members of the P. maniculatus species group has been problematic. Hooper (1968), and later Greenbaum et al. (1978), viewed P. polionotus to be an earlier peripheral isolate of grassland forms of P. maniculatus (bairdi and pallescens). Although allozyme and chromosome data (Greenbaum 1978; Avise et al. 1979; Robbins and Baker 1981; Stangl and Baker 1984) indicated that P. polionotus was sister to a clade containing taxa now recognized as P. sonoriensis and P. keeni, Avise et al. (1983) suggested that P. polionotus was paraphyletic with P. maniculatus and that P. polionotus may represent a peripheral population of P. maniculatus that underwent speciation approximately 1.5 mya. Herein, this species is loosely allied (no nodal support) with clades I ( P. sonoriensis), K ( P. maniculatus), and L ( P. labecula) but may have differentiated at a more recent date, approximately1.40 mya from the putative common ancestor with P. sonoriensis (Fig. 3).