Part 2

Diagnosis.--Among American species of the genus, over-all size medium (total length 94 mm); body long (54); tail short (39); forearm of medium length (37); tibia short (14.5); foot long (58 per cent of length of tibia); wing membrane arising from side of foot at distal end of metatarsal; calcar simple (not keeled) and 7 mm long; ears 15 to 16 mm long measured in the flesh from the notch (posteroventral border of the meatus); tragus, measured from same place, 7 to 8 mm high with posterobasal lobe; third metacarpal longest and second metacarpal shortest; fifth shorter than fourth; ears brownish; membranes of wing and tail blackish; uropatagium almost hairless, the few hairs that are present being almost invisible; pelage of back 5 mm long with some overhairs 8 to 9 mm long; basal 3 mm of fur black, remainder Cinnamon-Brown (capitalized color terms, after Ridgway, Color Standards and Color Nomenclature, Washington, D. C., 1912); outline of skull viewed dorsally similar to that of Myotis lucifugus; sagittal crest well developed; distance across upper canines equal to or slightly exceeding interorbital constriction; braincase low; two premolars on each side in upper jaw and also in lower jaw, the one remaining small premolar in contact with both the canine and the fourth premolar.

Remarks.--Myotis fortidens is known only from the Tropical Life-zone. The skin, without a skull, from Esquinapa, Sinaloa, agrees in color with the undoubted specimens of M. fortidens from Papayo, Guerrero, but can be matched also by selected skins of Myotis occultus from Blythe, Riverside County, California. Without the skull the reference of this specimen to M. fortidens is provisional. Reason for referring it to fortidens rather than to M. occultus is provided, however, by a series of eleven specimens of M. occultus from Alamos, Sonora. These are Saccardo's Umber rather than Cinnamon-Brown and they are geographically intermediate between the reddish M. occultus of California and the reddish M. fortidens of Mexico. Furthermore, these specimens from Alamos have large skulls of slightly different proportions than those of M. fortidens or than those of M. occultus from California; possibly the animals from Alamos are representative of the larger, duller-colored variation for which Hollister proposed the name Myotis baileyi (Proc. Biol. Soc. Washington, 22:44, March 10, 1909). This duller-colored type of animal intervenes between the geographic ranges of undoubted M. occultus and undoubted M. fortidens. The specimen from Esquinapa, in the geographic sense, is on the fortidens side rather than on the occultus side of the baileyi population. This geographic position is the basis on which the specimen from Esquinapa is referred to M. fortidens. The third premolar is lacking from each side of both the upper and the lower jaws of each individual of this series from Alamos.

The specimens of M. fortidens are all distinguishable by their color from other kinds of Myotis found in the same area. Occasional individuals of Myotis velifer, as for example three from Las Vigas, Veracruz, also are reddish but they are of brighter tone. In addition, the larger size and cranial features of these specimens of M. velifer permit ready differentiation of them from specimens of M. fortidens. One specimen (No. 32113) of M. fortidens from twenty kilometers east-northeast of Jesus Carranza is lighter than the others, being near (j) Cinnamon-Brown above and is lighter on the under-parts than on the upper parts. Another individual (No. 32112) is duller colored than the others, being Snuff Brown both above and below. Otherwise the specimens of M. fortidens agree in color.

Among named kinds of Myotis, M. fortidens resembles Myotis lucifugus and Myotis occultus. From the former, M. fortidens differs in possessing a strong sagittal crest and in lacking the third premolar in both the upper jaw and the lower jaw. M. fortidens lacks the glossy sheen found on the pelage of many individuals of M. lucifugus. From M. occultus, M. fortidens differs in having the rostrum (viewed from above) smaller in relation to the braincase. This is true of specimens with the teeth showing much wear as well as in specimens with the teeth unworn or only moderately worn. Also, M. fortidens is longer bodied as may be seen by comparing the measurements given here with those recorded for M. occultus by Miller and Allen (Bull. U. S. Nat. Mus., 144:100, May 25, 1928). We are agreed that M. fortidens is as closely related to M. occultus as to any other named kind of Myotis, and that it is more closely related to it than to most other species of the genus, but one of us (Dalquest) thinks that M. fortidens is specifically distinct from M. occultus, whereas the other author (Hall) inclines to the view that additional specimens from localities intermediate between the known geographic ranges of M. occultus and M. fortidens will reveal intergradation between the two kinds. However that may be, there is no proof at present of such intergradation and the binomial is therefore used for the Cinnamon Myotis.

Specimens examined.--Total number, 10, all from Mexico, each a skin with skull except the skin-only from Sinaloa. Sinaloa: Esquinapa, 1 (Amer. Mus. Nat. Hist.). Guerrero: Papayo, 2 (U. S. Biological Surveys Collection). Veracruz: 20 km. WNW Piedras Negras, 3 (Mus. Nat. Hist., Univ. Kansas); 20 km. ENE Jesus Carranza, 200 ft. elevation, 3 (Mus. Nat. Hist., Univ. Kansas). Tabasco: Montecristo, 1 (U. S. Biological Surveys Collection).

Additional record.--Tabasco: Teapa, the holotype of Myotis lucifugus fortidens Miller and Allen 1928.

University of Kansas Museum of Natural History, Lawrence, Kansas. Transmitted October 31, 1949.

CRANIAL MEASUREMENTS OF Myotis fortidens

Column headings:

A: Greatest length B: Condylobasal length C: Zygomatic breadth D: Interorbital constriction E: Breadth of braincase F: Mandible G: Maxillary tooth-row H: Maxillary breadth at M3 I: Mandibular tooth-row J: Wear of teeth

============================================================================== Sex No. Age Locality A B C D E F G H I J ------------------------------------------------------------------------------ 25030 Esquinapa .... .... ... ... ... .... ... ... ... ? 126650 Papayo 15.0 14.2 9.7 3.9 7.1 11.5 5.5 5.6 6.0 0 126651 Do. 15.1 13.8 9.4 3.8 6.8 10.6 5.6 5.9 6.0 0 17834 P. Negras .... 4.1 10.6 5.6 5.7 6.0 0 17835 Do. 15.5 14.9 9.6 4.2 7.2 11.0 5.7 6.0 6.1 2 17836 Do. 15.5 14.5 9.7 4.2 7.3 10.9 5.4 5.9 5.7 3 32112 J. Carranza 15.3 14.4 9.7 4.1 7.3 11.5 5.7 5.9 6.3 1 32113 Do. 15.0 14.0 9.5 4.2 7.2 10.9 5.5 5.9 5.9 1 32114 Do. 15.0 13.9 9.7 4.1 7.2 10.8 5.4 6.0 5.9 1 88.8.8.18 Teapa 15.0 13.8 9.6 3.8 7.4 .... 5.4 5.8 5.8 1 100231 Montecristo 15.0 14.1 9.0 4.0 7.2 11.4 5.8 ... 6.0 0 Average 15.2 14.2 9.5 4.0 7.2 11.0 5.6 5.9 6.0 ------------------------------------------------------------------------------

EXTERNAL MEASUREMENTS OF Myotis fortidens

Column headings:

A: Total length B: Head and body C: Tail D: Tibia E: Foot F: Forearm G: Thumb H: Third metacarpal I: Fifth metacarpal J: Ear from notch

=============================================================================== Sex No. Age Locality A B C D E F G H I J ------------------------------------------------------------------------------- 25030 Esquinapa .. .. .. 14.2 8.1 35.6 5.5 33.3 30.8 .. 126650 Papayo .. .. .. 14.7 8.2 38.3 5.4 35.1 32.4 126651 Do. .. .. .. 14.8 7.9 35.6 5.7 32.7 31.1 17834 P. Negras 95 55 40 14.7 9.0 37.0 5.7 33.8 32.0 15 17835 Do. 93 55 38 15.6 9.4 37.5 6.0 35.4 32.2 15 17836 Do. 94 55 39 14.3 8.4 37.6 6.0 34.5 32.7 15 32112 J. Carranza 94 53 41 14.5 8.9 38.2 5.0 35.1 33.8 16 32113 Do. 94 57 37 14.2 8.0 36.5 5.3 34.9 32.7 16 32114 Do. 90 53 37 .... ... 37.0 5.1 34.2 33.0 16 88.8.8.18 Teapa .. 46 39 15.6 8.0 38.6 6.2 34.8 33.0 100231 Montecristo 99 56 44 15.4 9.6 37.0 6.0 .... .... Average 94 53.8 39.4 14.8 8.6 37.2 5.6 34.4 32.4 15.5 -------------------------------------------------------------------------------

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