Eptesicus miradorensis (H. Allen, 1866 )

Ramírez-Chaves, Héctor E., Alarcón Cifuentes, Mallerly, Noguera-Urbano, Elkin A., Pérez, Weimar A., Torres-Martínez, Maria M., Ossa-López, Paula A., Rivera-Páez, Fredy A. & Morales-Martínez, Darwin Manuel, 2023, Systematics, morphometry, and distribution of Eptesicus fuscus miradorensis (H. Allen, 1866) (Chiroptera: Vespertilionidae), with notes on baculum morphology and natural history, Therya 14 (2), pp. 299-311 : 302-311

Eptesicus miradorensis (H. Allen, 1866)

S [cotophilus]. miradorensis H. Allen, 1866:287 ; type locality ̎Mirador,” Veracruz, México. [ Vespertilio (Eptesicus) fuscus ] miradorensis : Trouessart, 1904:77; name combination.

Eptesicus fuscus miradorensis : Miller, 1912:62; name combination.

Eptesicus fuscus pelliceus O. Thomas, 1920 b:361 ; type locality̎La Culata,” Merida, Venezuela.

E [ptesicus]. s [erotinus]. miradorensis : Koopman, 1994:120; name combination

Eptesicus brasiliensis : Niceforo Maria [2004]:225; in part.

LSID: urn:lsid:zoobank.org:act:39C7676F-8E25-4F4C-9B92-491AB516E427 .

Holotype: Not designated. The description was based on a fluid-preserved female (National Museum of Natural History - USNM 5411) collected by Dr. C. Sartorius in Mirador, Veracruz, México ( Davis 1966). According to Lyon and Osgood (1909), the specimen could not be located.

Emended diagnosis: Eptesicus miradorensis is the largest species of the genus with continental distribution in America (forearm: 48.54 to 51.13 mm). The skull is robust (greatest length of the skull: 19.79 to 20.59 mm; condyle-canine length: 17.7 to 18.47 mm) and presents well developed sagittal and lambdoidal crests, with a triangular appearance in caudal view. The dorsal fur is long (9.0 to 11.0 mm), lustrous, smooth,and shiny,with a brown color. The dorsal coloration is brown to golden yellow, dark to light, and bright, with two bands, the lower band being darker. The ventral coloration is lighter than the dorsal, with two bands, the lower band being darker. Both ventral coloration and dorsal have a mottled appearance. The wing and uropatagium membranes are dark. The ears are large (mean 17.5 mm) with the same coloring of the membranes. The tragus is elongated, reaching about 40 % of the length of the ears. The face is bare, and the skull is not flared and domed ( Figure 2 ).

Skeleton and baculum morphology. All specimens analyzed have seven cervical vertebrae, 11 thoracic, six lumbar, the sacral vertebrae fused into a single bone (the sacrum), and eight caudal vertebrae. The number of ribs is 10 ( Figure 3 ). The baculum of one specimen from México ( QM JM 6365) is small (length 0.83 mm, base width 0.54 mm, shaft width 0.34 mm), slightly convex dorsally, and slightly concave ventrally ( Figure 3 ). The baculum morphology of E. fuscus from North America (without specific locality but likely from the USA; see Hamilton, 1949) is similar in size (0.8 mm length), and general morphology to the one observed in E. miradorensis described here.

Assessment of morphometric variation of E. miradorensis . We reviewed 85 specimens from Colombia, Guatemala, México, Panamá, and Venezuela. All individuals match the diagnostic characters of E. miradorensis : large size ( FA 48.0 to 54.0 mm, GLS ~ 18.5 to 21.2 mm, weight 10 to 19.6 g), and long brownish hair (8 to 12 mm). Dorsal fur presents lighter tips. Ventral hair coloration is lighter than dorsal coloration. The membranes, ear, and rostrum are dark. The rostrum is naked ( Figure 2 ).

Specimens from the northern distribution range ( México) are similar in size to those from South America ( Table 2 ). Colombia-Venezuela and Mexican populations are similar in two wing measurements ( FA, IIIMT) between sexes; however, females have larger VMT (Mann - Whitney U - test, Z = - 2.031, p = 0.0423, n = 9) in South American populations, and IVMT (Z = - 1.979, p = 0.04783, n = 16) in Mexican populations. Similarly, both populations found no significant differences in the skull measurements ( GLS, CBL, POC, BBC, BM, ZB, M3M3, CM 3, ML).

The PCA analysis showed no clear distinction between North/Central and South American populations ( Figure 4 ), with specimens from México and Colombia overlapping the first component's negative and positive axis. Specimens from Central America (Guatemala-Panamá) were more centrally distributed along the PC1. The PCA of wing measurements shows that the first principal component accounted for most of the wing size variation (88 %, eigenvalue> 1; n = 30). For the cranial characters, the first two PC accounted for the largest variation (76.04 %: PC1: 49.42, PC2: 26.62, eigenvalues <1; n = 18). The variables that contributed most strongly to PC1 were GLS (0.6847) and ML (0.4946).

Distribution. We compiled 964 records from 1,098 localities in México, Costa Rica, Guatemala, Honduras, Panamá, Colombia, Venezuela, and Ecuador ( Figure 5 ). The localities cover an altitudinal range between 35 and 4,035 m, with an average greater than 1,951 m ( Table 3 ). The number of localities for each country and the elevation intervals are presented in Table 3 . The evaluation metrics showed a model with acceptable complexity (Features classes: H, hinge; regularization multiplier: 3; AUCtrain: 0.87; AUC difference = 5 %, Partial ROC: 0; Omission rate at 10P: 0.1; Number of parameters: 55). Seventeen predictors have a low correlation according with VIF, however, five of them had low impact on the Maxent model, and thus 12 variables were used (Bio2: Mean Diurnal Range, Bio3: Isothermality, Bio8: Mean Temperature of Wettest Quarter, Bio15: Precipitation Seasonality, Bio19: Precipitation of Coldest Quarter, Prec05: Precipitation May, Prec07: Precipitation July, Prec09: Precipitation September, Prec12: Precipitation December, Srad03: Solar Radiation March, Srad09: Solar Radiation September, Wind07: Wind Speed July). The maps of suitability and distribution ( Figure 5 ) showed that E. miradorensis has a potential distribution along the Andes in Ecuador to northern México. The higher suitability values are present in México, Guatemala, north Colombia, and Venezuela. The elevation and species suitability were positively correlated (r = 0.64, p-value <0.001), indicating low suitability values in the northern ( México) and southern ( Ecuador; Supplementary material). In the Mexican Transition Zone and Colombia Andes, the species had higher suitability values at medium and high altitudes (~ 2000 m MSL; Supplementary material), while in the records located at low altitudes such as in northern México, the species had low suitability. Interestingly, maps ( Figure 5 ; Supplementary material) showed that lowlands such as the Isthmus of Tehuantepec or the Nicaraguan depression and some Ecuadorian localities where the species has been recorded have inadequate climatic characteristics.

Eptesicus miradorensis

(n = 6) COLOMBIA: Caldas: MHN-UCa2022 MW926796 ; Cundinamarca: FMNH49154 OP157114 ; GUATEMALA: Chimaltenango: AMNH74304 OP157111 ; MÉXICO: Oaxaca: AMNH190167 OP157112 OP137059 ; PANAMA: Chiriquí: USNM541106 OP157110 ; VENEZUELA: Distrito Federal: AMNH143003 OP157113 OP137060 .

Figures

Figure 2. Details of the skull (ICN 17189; female from Department of Santander, Colombia) of E. miradorensis. a. Ventral view. b. Dorsal view. c. Lateral view. d. Alive specimen from Serranía del Perijá, Colombia (ICN uncatalogued) shows long brownish hair and a dark,naked face.

Figure 3. Details of the skeleton (a-b) and baculum (c-e) of Eptesicus miradorensis (QM JM 6365) from México. a.Dorsal view. b.Ventral view. c.Baculum shape and position (green) embedded in the penis (grey structure). d:Dorsal view of the baculum. e.Ventral view of the baculum.

Figure 4. PCA plots of (a) cranial and (b) external measurements of Eptesicus miradorensis from different localities along its distribution range.

Figure 5. a.Suitability map ofEptesicus miradorensis in America using the Maxent algorithm. The higher suitability values are present in México,Guatemala,north Colombia, and Venezuela. b. Binary distribution map of Eptesicus miradorensis using the 10-percentile threshold value. Red points represent the species records.