Eumops delticus O. Thomas 1923

Eumops delticus O. Thomas, 1923 Summary of captures. One female (CMARF 2122). External measurements and weight. TLB: 107.00, TL: 42.00, LHL: 6.00, EL: 19.00, W: 11.00. Morphological description. Dorsal fur is cinnamon brown, with the basal portion of the hairs paler than the tips. The color of ventral and dorsal fur shows slight contrast, with the hairs around the neck and shoulders darker than the rest (Fig. 4). The upper lips are slightly wrinkled. The upper border of the nares is surrounded by small and obtuse warts. Small hairs cover internarial ribs. Ears broad, rounded, and joined at a common point. The upper border of ears with pointed and fleshy warts. The inner keel of the ears reaching the antitragus, not extending beyond the posterior part of this structure. Antitragus long and semicircular. The tragus is slightly subquadrate, with the upper extreme narrower, giving an obelisk appearance. The skull is broader across the rostrum with an evident depression near the mastoid bone, the braincase is deeper (globular shape), and the lateral region is curved (Fig. 5). Interparietal bones are elongated, clearly visible in the lateral view of the skull. Sagittal and lambdoidal crests developed. Upper incisors with divergent tips projected forward, forming an angle of 45 ° with the canines. Upper canines and first premolars in contact. The second upper premolars have protocones that are thin and not robust (Fig. 5). The third upper molars have a well-developed commissure. The posterior part of the third upper molar does not extend beyond the maxillary bone (Fig. 6). Palate extends beyond the level of the third upper molar (Fig. 6). Mesopterygoid fossa deep and narrower anteriorly, with basisphenoid pits deep, wider posteriorly and oval in shape (Fig. 5). Rib between basisphenoid pit thin. Incisive foramen large. The mandible is slender, with an articular process that is wider and more developed than the condylar and coronoid processes. Lower incisors are bilobed. The values of some cranial measurements of the female collected and comparable data from other studies, are shown in Table 1. Identification. Externally, the forearm length (> 40 mm) and the shape and depth of the basisphenoid pits (deep and wider posteriorly) separate this species from Eumops hansae (Eger 2008). When comparing differences to the closest congeners morphologically, Eumops patagonicus and Eumops bonariensis, E. delticus can be differentiated from E. patagonicus by being larger in some external and cranial measurements, including the lengths of forearm and skull, respectively. Additionally, the extension of the internal keel of the ears, not reaching the anterior antitragus area in E. patagonicus, is a discreet characteristic that can help differentiate E. patagonicus from E. delticus (Díaz et al. 2021). However, Bernardi et al. (2009) identified an individual as E. patagonicus with an internal keel reaching the middle region of the antitragus. Concerning differentiation of E. bonariensis, cranial morphological characters are provided in the Discussion to aid in distinguishing both species.