Cynomops planirostris ( Peters, 1866 )

López Berrizbeitia, M Fernanda & Díaz, M Mónica, 2021, Cynomops planirostris (Chiroptera: Molossidae), Mammalian Species 53 (1013), pp. 174-185 : 175-181

Cynomops planirostris ( Peters, 1866)

Southern Dog-faced Bat

M [olossus ( Molossops )]. planirostris W. Peters, 1866:575 , footnote. Type localities “ British Guiana, Barra do Rio Negro [ Brazil], and Buenos Aires [ Argentina];” restricted to British Guiana by Cabrera (1958:119), but later corrected to Cayenne, French Guiana, based on information associated with the lectotype, by Carter and Dolan (1978:86).

[ Molossus (Myopterus) ] planirostris: Trouessart, 1897:142 . Name combination.

Molossus planirostris paranus Thomas, 1901a:190 . Type locality “Para,” Pará, Brazil (see “Nomenclatural Notes”).

[ Molossus (Myopterus) planirostris ] paranus: Trouessart, 1904:101 . Name combination.

Molossops planirostris: Miller, 1907:248 . Name combination.

Molossops paranus: Miller, 1907:248 . Name combination.

Cynomops planirostris: O. Thomas, 1920:189 . Generic description; first use of current name combination.

Cynomops paranus: O. Thomas, 1920:189 . Name combination (see “Nomenclatural Notes”).

Molossops planirostris paranus: Vieira, 1942:432 . Name combination.

Molossops [( Cynomops )] planirostris planirostris: Cabrera, 1958:119 . Name combination.

Molossops [( Cynomops )] planirostris paranus: Cabrera, 1958:119 . Name combination.

Cynomops planirostris paranus: Goodwin, 1958:5 . Name combination.

Molossops greenhalli: Mares, Willig, Streilein, and Lacher, 1981:112 . Not Cynomops greenhalli Goodwin, 1958 .

CONTEXT AND CONTENT. Context as for genus. Cynomops planirostris is monotypic ( Eger 2008; Burgin 2020).

NOMENCLATURAL NOTES. Thomas (1901a) described Cynomops paranus as a subspecies of C. planirostris , but in 1920 he elevated paranus to a full species. Subsequently, authors such as Koopman (1978, 1993, 1994) and Sanborn (1941) continued to consider C. paranus to be a subspecies of C. planirostris , whereas other authors recognized C. paranus as a species, distinct from C. planirostris ( Handley 1976; Williams and Genoways 1980; Barquez 1987; Simmons and Voss 1998; Barquez et al. 1999; Eger 2008). Gregorin and Taddei (2002) included C. paranus in C. planirostris , due to overlapping qualitative and morphometric characters that make differentiation of these taxa difficult. Molecular and morphometric analysis by Peters et al. (2002) supported a sister relationship of C. paranus and C. planirostris and indicated that C. milleri should not be considered synonymous with C. planirostris , as previously suggested by Koopman (1978, 1993, 1994). As currently recognized, C. milleri was reelevated to a species ( Eger 2008). Moras et al. (2016, 2018) conducted phylogenetic, molecular, and morphological analyses and concluded that Cynomops paranus of Thomas (1901a) was a junior synonym of C. planirostris . In their molecular analyses, specimens previously attributed to C. paranus were recovered in clades with other taxa including C. planirostris and C. milleri ( Moras et al. 2016, 2018), and in a monophyletic clade currently recognized as C. freemani ( Moras et al. 2018) . Unfortunately, neither Moras et al. (2016) nor Moras et al. (2018) identified the specimens included in their analyses that would have been previously attributed to C. paranus , other than the holotype. However, specimens previously recognized as C. paranus from Panama are now recognized as C. freemani and those from Ecuador as C. tonkigui . The consideration of Cynomops paranus as a synonym of C. planirostris was based on morphological comparison of the types of these two species which Moras et al. (2016) were unable to differentiate.

The distribution of C. paranus was recorded from Guyana, Surinam, French Guiana, Brazil, northern Argentina, eastern Peru, Columbia, and as far north as Honduras ( Eger 2008). The characteristic dark venter color observed in C. paranus ( Thomas 1901a; Simmons and Voss 1998) was also present in a series of C. planirostris from the Brazilian Amazonia, Para, and Amazonas states and could be geographical or individual variation ( Moras et al. 2016).

Cynomops milleri was originally described as a species within Molossops ( Osgood 1914) , treated as a subspecies of C. planirostris ( Koopman 1978) , and synonymized with C. paranus ( Simmons and Voss 1998) . According to Peters et al. (2002) the relationship between C. paranus and C. milleri still needs to be examined. Currently C. milleri is considered a valid species and distinct from C. planirostris , and some specimens previously identified as C. paranus now are included as C. milleri ( Eger 2008; Moras et al. 2016, 2018).

Common name in Spanish for this species is “moloso de pecho blanco” ( Barquez 2006). The etymology of the genus name is: cyn —kyon, genitive kynos (Greek), dog + mops, a group of mastiff bats ( Conisbee 1953; Braun and Mares 1995), and the species name is: plan —planus (Latin), flat + rostr — rostrum (Latin), snout, muzzle; the species name refers to the flattened snout ( Braun and Mares 1995).

DIAGNOSIS

Cynomops is distinguished from Molossops by a smooth face, rounded ears, and rounded antitragus with a broad base (as opposed to the presence in Molossops of papillae on both the face and nostrils, triangular ears, and a small, pointed antitragus); by the degree of separation of the ears (4 mm or less in Cynomops ; 4.5 mm in Molossops ); by the more robust skull with a pronounced nuchal crest and more robust mandible; by the number of lower incisors (1/ 2 in Cynomops ; 1/ 1 in Molossops ); by having M3 without a premetacrista (with a partial premetacrista in Molossops ); and by having digit IV of the wing with the second phalanx shorter than the first phalanx (first and second phalanges of similar length in Molossops — Thomas 1920; Barquez et al. 1993, 1999; Gregorin and Cirranello 2015).

Cynomops planirostris ( Fig. 1 ) can be distinguished from all other species within the genus by having ventral coloration paler than dorsal, gular and midventral region usually whitish or pale buff, bicolored dorsal hairs, ears that almost touch at the base (separated by only 1–2 mm), and incisive foramina arranged in the shape of equilateral triangle ( Eger 2008; Díaz et al. 2011, 2016; Moras et al. 2016, 2018). Cynomops planirostris has weakly developed basisphenoid pits and a relatively low and short rostrum with the anterior face of the lacrimal ridges sloping posteriorly ( Eger 2008). A molecular analysis by Peters et al. (2002) supports the autapomorphy of the white venter as diagnostic for C. planirostris (excluding C. paranus ). However, according to Moras et al. (2016) the darker dorsal and ventral pelage coloration observed by some authors ( Thomas 1901a; Simmons and Voss 1998; Barquez et al. 1999) is also present in some specimens of C. planirostris from Brazil and may reflect geographical or individual variation.

GENERAL CHARACTERS

Body size is small, dorsal color varies from chocolate brown to grayish brown, and individual dorsal hairs are bicolored, with the basal one-half of each hair pale buff or cream. Ventral coloration is paler than dorsal with gular and midventral region usually whitish, pale buff or almost orangish, and most specimens of Cynomops planirostris have a prominent pale, generally white, patch on the throat, neck, chest, and part of the abdomen ( Peters 1866; Williams and Genoways 1980; Linares 1998; Barquez et al. 1999; Gregorin and Taddei 2002; Eger 2008; Moras et al. 2016). In the female the ventral patch is less evident than in the male ( Olrog and Barquez 1979). The membranes are dark brown; fur is short (2 or 3 mm), soft, velvety, and extends on the venter along the plagiopatagium and over the uropatagium to the sides of the tail; dorsally, the fur extends over the basal part of the uropatagium, to the sides of the forearm in the propatagium and plagiopatagium, and over the fifth metacarpal; forearms are naked without warts ( Linares 1998; Barquez et al. 1999). The ears are wide and rounded; the ear keel is well-marked and extends midway across the internal part of the ear; the tragus is small, higher than wide, with a rounded tip and, externally, has a small bump at its midpoint; the antitragus is well-developed, semicircular, and extends forward as a fold of skin that reaches the corner of the mouth ( Husson 1962, 1978; Barquez et al. 1999). The muzzle is notably procumbent, flat, and wide; the upper lip has a fringe of fine hairs, and the lower lip is naked; the tail is long, with two-fifths of its length projecting free beyond the posterior margin of the uropatagium; and the calcars are long and extend for one-half the distance between the feet and tail ( Peters 1866; Husson 1962, 1978; Linares 1998; Barquez et al. 1999; Emmons and Feer 1999; Moras et al. 2016).

The skull of C. planirostris ( Fig. 2 ) is similar to that of other species of Cynomops , with the rostrum relatively low and short; the lacrimal ridge is conspicuous and its anterior face slopes smoothly to the forehead as in C. abrasus (cinnamon dog-faced bat); the incisive foramina are located closer to the accessory foramen, and the arrangement of the three foramina (incisive and accessory) forms an equilateral triangle as in C. mastivus (Thomas’s dog-faced bat); the basisphenoid pits are shallow ( Husson 1962, 1978; Eger 2008; Moras et al. 2016). There is a lack of clarity concerning the presence and absence of basisphenoid pits because Debaeremaeker and Fenton (2003) determined that basisphenoid pits are present in C. planirostris and are absent in C. paranus . Moras et al. (2016), in their emended diagnosis, listed shallow basisphenoid pits as a diagnostic characteristic of C. planirostris but failed to comment if this character allowed differentiation from specimens previously assigned to C. paranus .

Ranges of external measurements (mm) of 13 specimens from Argentina ( Barquez et al. 1999, 2011; Idoeta et al. 2012) were: total length, 83.0–94.0; tail length, 21.0–31.0; length of hind foot, 6.0–8.0; ear length, 11.0–16.10; forearm length, 31.19–35.0. Body mass (g) was 10.5–15.0 (n = 10— Idoeta et al. 2012). In Brazil ( Vizotto and Taddei 1976), means ± SD (mm; range, coefficient of variation) for 15 males and 15 females, respectively, were: head–body length, 55.7 ± 0.5 (51.0–59.0, 3.3), 52.9 ± 0.3 (50.5–54.5, 2.4); tail length, 25.2 ± 0.5 (21.5–28.0, 7.1), 25.6 ± 0.3 (23.5–28.0, 5.2); height of ear, 13.3 ± 0.1 (12.5–14.0, 3.9), 12.7 ± 0.2 (11.5–14.0, 5.5); height of tragus, 3.3 ± 0.1 (3.0–3.5, 7.3), 3.1 ± 0.05 (3.0–3.5, 6.7); forearm length, 31.6 ± 0.3 (30.0–34.0, 3.4), 30.7 ± 0.15 (29.5– 31.5, 1.9); length of metacarpus III, 32.2 ± 0.3 (30.5–34.5, 3.5), 31.0 ± 0.2 (29.5–32.0, 2.2); length of phalanx I, 14.0 ± 0.2 (12.5–15.0, 5.3), 13.3 ± 0.1 (12.5–14.5, 3.4); length of phalanx II, 12.5 ± 0.2 (11.5–14.0, 5.2), 11.7 ± 0.2 (10.5–13.0, 6.4); length of metacarpus IV, 31.0 ± 0.3 (29.0–33.0, 3.4), 29.8 ± 0.2 (28.5–31.0, 2.4); length of phalanx I, 11.7 ± 0.2 (10.5–12.5, 5.5), 11.1 ± 0.1 (10.5–11.5, 2.7); length of phalanx II, 4.1 ± 0.1 (3.5–4.5, 9.7), 4.0 ± 0.1 (3.5–4.5, 6.7); length of metacarpus V, 20.3 ± 0.3 (19.0–22.5, 5.0), 19.5 ± 0.1 (18.5–20.0, 2.6); length of phalanx I, 8.5 ± 0.1 (7.5–9.5, 6.0), 8.3 ± 0.1 (7.5–9.0, 5.5); length of phalanx II, 3.1 ± 0.1 (3.0–3.5, 7.3), 3.7 ± 0.1 (2.5–3.5, 8.4); tibia length, 10.5 ± 0.1 (10.0–11.5, 4.4), 10.0 ± 0.1 (9.5– 10.5, 4.4); length of hind foot, 6.5 ± 0.1 (6.0–7.0, 4.1), 6.2 ± 0.1 (6.0–6.5, 4.0). Husson (1978) presented external measurements (mm) from one female and one male, respectively, from British Guiana: forearm length, 32.0, 32.5; length of metacarpus III, 33, 35; length of phalanx I, 15, 15; length of phalanx II, 13, 14; length of phalanx III, 3, 3; length of metacarpus IV, 32.5, 34.0; phalanx I, 11, 10; phalanx II, 4.5, 4.0; length of metacarpus V, 20, 21; length of phalanx I, 9, 10; length of phalanx II, 3, 3; tail length, 30, 29. In Paraguay, López-González (2005) published means ± SD (mm; range), for seven females and four males, respectively: total length, 88.9 ± 8.17 (78.0–100.0), 87.0 ± 0.81 (86.0–88.0); tail length, 26.6 ± 2.76 (23.0–30.0), 25.8 ± 0.96 (25.0–27.0); length of hind foot, 8.4 ± 0.98 (7.0–10.0), 8.0 ± 1.41 (7.0–10.0); ear length, 14.3 ± 1.11 (13.0–16.0), 15.0 ± 0.00 (n = 3); forearm length, 31.2 ± 1.02 (29.9–33.1), 32.4 ± 0.24 (32.1–32.6); length of metacarpus III, 32.6 ± 1.21 (30.4– 34.0), 35.1 ± 1.35 (34.0–37.0); and body mass (g), 9.3 ± 1.01 (8.0–10.8), 11.1 ± 1.87 (9.0–12.5; n = 3). Range of external measurements (mm) and mass (g) of three females from Perú (Díaz 2011) were: total length, 81–83; length of tail, 26–27; length of hind foot, 8–9; ear length, 14–15; forearm length, 30.5–31.8; mass, 9.00–10.2. In Venezuela, Linares (1998) provided the ranges of the following external measurements (mm): head–body length, 54–63; tail length, 24–30; length of hind foot, 9–10; ear length, 15–16; forearm length, 29.5–34.6; and mass (g), 10.5–14.9. Moras et al. (2018) provided means (range and n) for males and females, respectively, of forearm length (mm) 33.57 (31.36–36.56, 50); 32.20 (29.00–34.92, 83) and body mass (g) 12.63 (10.00–15.00, 10); 10.86 (8.60–14.00, 15).

Ranges of skull measurements (mm; n) of specimens from Argentina ( Barquez et al. 1999, 2011; Idoeta et al. 2012) were: greatest length of skull, 13.30–17.80 (13); condylobasal length, 14.78–16.74 (12); least interorbital breadth, 6.18–7.18 (13); zygomatic breadth, 10.56–11.58 (10); postorbital constriction, 3.91–4.60 (13); breadth of braincase, 7.68–8.30 (13); length of maxillary toothrow, 5.89–7.00 (13); palatal length, 6.16–7.10 (13); mastoidal breadth, 9.68–11.50 (10); length of mandibular toothrow, 6.30–7.50 (13); length of mandible, 11.69–13.58 (12); width across canines, 4.07–5.0 (13); width across molars 6.82–8.0 (13). Peters et al. (2002) reported the following means (mm; ranges) for six females and 12 males, respectively: greatest length of skull, 15.9 (15.0–16.4), 17.0 (16.2–18.0); zygomatic breadth, 10.4 (9.9–10.9), 10.9 (10.3–11.8); postorbital width, 4.3 (4.0–4.7, 4.2 (3.9–4.4); breadth of braincase, 8.0 (7.5–8.4), 8.1 (7.7–8.4); length of maxillary toothrow, 5.8 (5.5–6.1), 6.3 (5.7–6.6); mastoidal breadth, 9.9 (9.3–10.7), 10.4 (9.4–11.8); width across lacrimal, 6.5 (6.1–7.0), 6.9 (5.9–7.5); dentary length, 10.9 (10.3–11.7), 11.8 (10.9–12.4); width across molars, 7.1 (6.7–7.5), 7.3 (7.1–7.8). Giménez and Giannini (2016) provided means (mm; ranges) of craniodental measurements of six specimens: condylobasal length, 15.36 (14.43–16.76); zygomatic breadth, 10.55 (9.69–11.34); height of braincase, 5.62 (4.72–6.02); mastoidal breadth, 9.44 (9.15–9.98); maximum external width between left and right upper molars, 7.35 (6.87–7.94); length of maxillary toothrow, 6.23 (5.88–6.75); postorbital constriction, 4.30 (4.15–4.62); length of rostrum, 4.58 (4.25–5.08); palatal length, 6.83 (6.41–7.54); width across upper canines, 4.48 (4.14–4.84); length of upper canine, 2.59 (1.99–3.25); length of mandible, 12.0 (11.41–12.89); height of mandibular body at lower third premolar, 2.13 (1.86–2.54); length of lower canine, 2.29 (1.39–2.88); length of mandibular toothrow, 6.90 (6.59–7.47); and three measurements of the coronoid process (H1, H2, H3—see details in Giménez and Giannini 2016:4, figure 2), 3.55 (3.19–3.98), 3.53 (3.26–4.01), 3.57 (3.34–3.69). Means (mm; ranges, n) of cranial measurements ( Moras et al. 2018) for females and males, respectively, were: greatest length of skull, 15.40 (14.11–16.20, 93), 16.33 (15.21– 17.29, 46); greatest breadth of braincase, 15.40 (14.11–16.20, 93), 16.33 (15.21–17.29, 46); mastoidal breadth, 10.06 (9.27– 10.98, 89), 11.03 (9.68–11.91, 40); rostral width, 6.57 (5.94– 7.08, 96), 7.32 (6.49–7.95, 49); condyloincisive length, 15.33 (14.34–16.39, 87), 16.65 (15.29–17.52, 45); zygomatic breadth, 10.52 (9.54–11.19, 80), 11.19 (9.88–12.00, 46); postorbital breadth, 4.22 (3.80–4.56, 96), 4.33 (3.92–4.90, 48); length of maxillary toothrow, 6.02 (5.52–6.63, 97), 6.45 (5.91–6.97, 49); width across molars, 7.21 (6.34–7.68, 97), 7.49 (7.02–8.10, 49); width across canines, 4.23 (3.88–5.07, 97), 4.85 (4.34–5.25, 49); and length of mandible, 11.27 (10.20–12.19, 97), 12.13 (11.12–12.83, 48). In Brazil ( Vizotto and Taddei 1976), means ± SD (mm; range, coefficient of variation) for 15 males and 15 females, respectively, were: total length, 15.4 ± 0.1 (14.9–15.9, 1.9), 14.5 ± 0.2 (14.1–15.0, 1.8); condylobasal length, 14.9 ± 0.1 (14.3–15.6, 2.1), 13.9 ± 0.1 (13.6–14.3, 1.7); condyle-canine length, 14.4 ± 0.1 (13.5–15.2, 2.7), 13.5 ± 0.05 (13.1–13.8, 1.6); basal length, 12.7 ± 0.1 (12.0–13.3, 2.6), 12.0 ± 0.1 (11.4–12.4, 2.1); palatal length, 6.2 ± 0.04 (6.0–6.4, 2.4), 5.8 ± 0.04 (5.5– 6.0, 3.1); length of maxillary toothrow, 5.9 ± 0.04 (5.6–6.2, 3.0), 5.5 ± 0.03 (5.3–5.7, 2.2); length of mandibular toothrow, 6. 3± 0.04 (6.0–6.7, 2.8), 6.1 ± 0.03 (5.9–6.2, 1.7); length of mandible, 11.1 ± 0.05 (10.8–11.5, 1.8), 10.4 ± 0.05 (10.1–10.8, 1.9); width across canines, 4.5 ± 0.04 (4.3–4.8, 3.6), 4.2 ± 0.04 (4.0–4.4, 3.9); width across molars, 7.1 ± 0.05 (6.8–7.5, 3.0), 6.8 ± 0.03 (6.7–7.1, 1.7); postorbital breadth, 4.1 ± 0.03 (3.9–4.3, 2.7), 4.0 ± 0.02 (3.8–4.1, 2.4); zygomatic breadth, 10.4 ± 0.1 (10.0–11.0, 2.5), 10.0 ± 0.03 (9.7–10.1, 1.2); breadth of braincase, 7. 8± 0.04 (7.4–8.0, 1.9), 7.6 ± 0.04 (7.3–7.8, 2.0); mastoidal breadth, 10.0 ± 0.1 (9.6–10.6, 3.7), 9.4 ± 0.05 (9.0–9.7, 2.1); height of braincase, 5.3 ± 0.02 (5.2–5.5, 1.7), 5.2 ± 0.03 (5.0–5.3, 2.4). Husson (1978) provided skull measurements (mm) of one female and one male, respectively, from British Guiana: greatest length, 15.6, 17.9; condylobasal length, 15.3, 16.2; condyle to front of canine, 14.8, 16.0; basal length, 13.2, 14.3; palatal length, 6.5, 7.5; zygomatic breadth, 10.7, 11.6; breadth of braincase, 8.3, 8.7; height of braincase, 5.8, not available; mastoid breadth, 10.3, 11.7; interorbital constriction, 4.4, 4.3; width across molars, 7.3, 7.7; width across canines at the cingula, 4.2, 5.0; upper toothrow, C–M3, 6.1, 6.6; lower toothrow, c–m3, 6.5, 7.1; length of mandible, 11.1, 11.8. In Paraguay, López-González (2005) cited means ± SD (mm; range, n) of the following measurements for females and males, respectively: greatest length of skull, 15.9 ± 0.64 (15.0–16.7, 7), 17.1 ± 0.26 (16.9–17.5, 4); condylobasal length, 15.2 ± 0.62 (14.2–15.9, 7), 16.5 ± 0.49 (15.9–17.1, 4); mastoidal breadth, 10.0 ± 0.27 (9.6–10.4, 7), 10.8 ± 0.24 (10.5–11.1, 4); zygomatic breadth, 10.5 ± 0.27 (10.0–10.7, 6), 11.3 ± 0.36 (10.9–11.6, 4); postorbital constriction, 4.1 ± 0.16 (3.9–4.4, 7), 4.3 ± 0.09 (4.2–4.4, 4); width across canines, 4.2 ± 0.10 (4.0–4.3, 7), 4.9 ± 0.14 (4.8–5.1, 4); width across molars, 7.2 ± 0.11 (7.1–7.4, 7), 7.6 ± 0.22 (7.5–7.9, 4); length of maxillary toothrow, 5.8 ± 0.19 (5.6–6.1, 7), 6.5 ± 0.23 (6.3–6.8, 4); length of mandibular toothrow, 6.3 ± 0.26 (5.9–6.6, 7), 7.0 ± 0.33 (6.6–7.3, 4). Additional external and cranial measurements are provided by Anderson (1997), Simmons and Voss (1998), Díaz (2011), dos Santos et al. (2015), and Moras et al. (2016).

DISTRIBUTION

Cynomops planirostris occurs in South America on the eastern slopes of the Andes and is known from the lowlands and highlands at elevations of 4–2,500 m in French Guiana, Guyana, Suriname, Venezuela, Colombia, Peru, Bolivia, Brazil, Paraguay, and Argentina ( Fig. 3; Moras et al. 2016).

In Colombia, C. planirostris is found in theAndean, Amazon, and Orinoco regions in the following departments: Amazonas, Casanare, Meta, Northern Santander, Putumayo, Tolima, and Vichada ( Aellen 1970; Muñoz Arango 2001; Peters et al. 2002; Bejarano-Bonilla et al. 2007; Solari et al. 2013). In Venezuela, it is known from the southern Orinoco and Los Llanos ( Linares 1998) and from the Amazonas, Apure, Bolivar, Guárico, Miranda, Monagas, and Yaracuy states ( Handley 1976; Williams and Genoways 1980; Linares 1998; Peters 2002; Eger 2008; Delgado-Jaramillo et al. 2016). In French Guiana, C. planirostris is listed for the district of Cayenne ( Eger 2008; Moras et al. 2018). In Suriname the species is listed for Paramaribo and Sipaliwini districts ( Husson 1978; Eger 2008); the locality referenced by Peters et al. (2002) as Sipaliwini Airstrip is located in Sipaliwini District and not in Nickerie District as previously reported. In Guyana, C. planirostris is recorded in: Berbice, East Demerara-West Coast Berbice, Upper Demerara-Berbice, Upper Essequibo, Upper Takutu-Upper Essequibo, Rupunnini ( Peters et al. 2002; Moras et al. 2016). In Peru, it is listed for the departments of Loreto, Ucayali, Huánuco, San Martín, Puno, Madre de Dios, and Cusco ( Solari et al. 1999; Díaz 2011). In Bolivia, C. planirostris inhabits the Amazonian forests, the Cerrado, and the Chiquitanos forests in the departments of Beni, La Paz, Pando, and Santa Cruz ( Anderson 1997; Siles 2007). In Brazil, it is widely distributed, and has been recorded in 18 states (see dos Santos et al. 2015). In Paraguay, C. planirostris is found in nine departments: Alto Paraguay, Boquerón, Central, Concepción, Cordillera, Misiones, Paraguarí, Presidente Hayes, and San Pedro (see López-González 2005). In Argentina, C. planirostris is known from the provinces of Salta, Jujuy ( Barquez and Díaz 2009; Barquez et al. 2011), and Misiones ( Idoeta et al. 2012).

The specimens from Panamá and Ecuador previously identified as C. planirostris are now recognized as two new species, C. freemani (Freeman’s dog-faced bat) and C. tonkigui (Waorani dog-faced bat), respectively ( Moras et al. 2018). No fossils are known.

FORM AND FUNCTION

Form. —The dental formula of Cynomops planirostris is i 1/2, c 1/1, p 1/2, m 3/3, total 28. Upper incisors are about one-half the height of the canines, with their bases in contact and tips divergent, and are separated from the canines by a small diastema ( Husson 1962, 1978). In some specimens, the posterior border of the cingulum of the upper canines does not project posteriorly, thus leaving a small space between the canines and the premolars; the posterior margin of P4 is in contact with the anterior margin of Ml (or are separated by a space); a well-developed median ridge is present in the lingual face of the second lower premolar ( Husson 1962, 1978; Barquez et al. 1999; Moras et al. 2016). M3 lacks a third commissure ( Freeman 1981; Barquez et al. 1999). Lower incisors are small, bifid, and crowded, with their height being much less than that of the cingulum of the canines; the two lower premolars are in contact with each other with p3 being shorter than p4 ( Husson 1962, 1978).

In specimens from Brazil, the mean external and cranial measurements of males were greater than the means of females except for the length of tail ( Vizotto and Taddei 1976). Peters et al. (2002) and Moras et al. (2018) reported that mean cranial measurements of males were larger than those of females from samples across northern South America.

The results from principal components analysis indicated that C. planirostris , specimens formerly recognized as C. paranus , C. greenhalli (Greenhall’s dog-faced bat), and C. mexicanus (Mexican dog-faced bat) cannot be definitively separated based on size ( Peters et al. 2002). The overlap in size has been a major cause of taxonomic confusion within this group; although C. planirostris is the smallest taxon, the size of the largest individuals of C. planirostris overlap primarily with individuals previously recognized as C. paranus ( Peters et al. 2002) . These specimens of C. paranus are now considered either a synonym of C. planirostris or have been reassigned to C. freemanii , C. tonkigui , or C. milleri (Miller’s dog-faced bat—see Moras et al. 2016, 2018).

Van Staaden and Jones (1997) studied the morphology of the dorsal hair of 31 species of New World molossid bats using both conventional light microscopy and scanning electron microscopy. The dorsal hair of C. planirostris was described as follows: base moderately curved, with greatest width at midpoint of hair; cuticle and cortex light and moderately pigmented, respectively, forming clear horizontal bands.

Comelis et al. (2017) described the external morphology and histomorphology of the penis of C. planirostris and other species of molossid bats. In C. planirostris , the length of the glans penis reaches 1.74 mm, and it has an ellipsoidal morphology with a rounded apex. The ventral surface of the glans has two median wrinkles with an hourglass-like morphology; above these wrinkles is a ventromedial lanceolate-shaped ridge, which does not extend to the apex. The urinary meatus is located behind this ridge. The ventral lanceolate ridge is long and narrow, presenting laterally two pairs of epithelium domes, a smaller internal pair and a larger external pair. On the dorsal surface there is a deep median groove, which extends the entire length of the glans separating it into two equivalent regions. Although the groove reaches the distal apical rounded portion, it does not extend toward the ventral surface. The outer surface of the glans is covered by small, proximally directed, spiniform epidermal projections, with bases larger than tips. Regarding the internal penile morphology, the prepuce of C. planirostris has a keratinized epithelium externally and internally and presents little pigmentation; the glans is covered by a thick layer of keratinized epithelium, which gives rise to small spiniform projections. The cavernous bodies are not well-developed and are positioned ventrally. However, Gregorin and Cirranello (2015) mentioned that the accessory cavernous tissue occupies a considerable volume of the penis in C. planirostris . The corpora cavernosa shows a low level of development, is located ventrally, and the urethral cap is absent ( Gregorin and Cirranello 2015). Cynomops planirostris does not have a baculum. The baculum was hypothesized as present in the common ancestor of all bats (present in 99% of taxa), followed by five independent losses, among them Molossops temminckii (dwarf dog-faced bat) and C. planirostris (absent in 76% of the individuals— Schultz et al. 2016).

Gregorin (2003) conducted descriptive and comparative studies on the tongue of 19 Molossidae , one Mystacinidae , and four Vespertilionidae species and described the shape of the tongue in Cynomops as quadrangular and centrally curved. Fungiform papillae were distributed regularly in the lateral surface from the middle to the posterior region of the tongue and were proportionally larger in this genus than in other Molossidae and Vespertilionidae taxa. The dorsal region between the lobe and vallate papillae was slightly naked, with some irregularly spread fungiform papillae.

Function. — Giménez and Giannini (2016) showed a clear segregation in morphospace among the majority of molossid species that inhabit Argentina and the vast region of the “Southern Cone” of South America. In their analysis, C. planirostris , C. paranus (now a synonym of C. planirostris or included in several species of Cynomops ), and Nyctinomops laticaudatus (broad-eared free-tailed bat) shared the space near the centroid with varying degrees of overlap and exhibited skulls of intermediate structure and of very-small-to-small size. According to these authors, the morphofunctional pattern was determined principally by the evolutionary history of the family in the Neotropics, with major events involving the expansion of occupied space beginning some 20 Ma with the emergence of the large-bodied molossids ( Eumops ) and the smallest species of Molossops and Cynomops .

Wing morphology has a direct influence on the flight maneuverability, agility, and speed of bats. Marinello and Bernard (2014) characterized the wing shape of 51 bat species (including C. planirostris ) found in Brazilian Amazonia by measuring the aspect ratio and relative wing load for each species. They found high variability in wing shape: aspect ratio varied from 5.0862 ( Lophostoma brasiliense , pygmy round-eared bat) to 8.2774 ( Molossops paranus , now probably C. planirostris ). These highest values of aspect ratio indicate long, narrow wings associated with higher aerodynamic efficiency and lower energy cost during flight.

Cynomops planirostris emits search-phase echolocation calls within a narrow frequency range of 20–35 kHz, allowing the detection of a rather ample range of differently sized potential prey items, while maximizing the response time for successful prey capture ( Jung et al. 2014). These same authors reported considerable differences in echolocation call structure between Cynomops and Molossops ; this agrees with molecular data indicating that both genera are divergent lineages meriting separate taxonomic recognition.

ONTOGENY AND REPRODUTION

Cynomops planirostris probably has more than one reproductive peak per year; in Brazil pregnant females were recorded between May and October ( Reis et al. 2013) and from September to January ( Peracchi et al. 2006). Females in advanced pregnancy were found in January and were lactating in February ( Vizotto and Taddei 1976; Peracchi et al. 2006; Reis et al. 2013). Vizotto and Taddei (1976) recorded embryos in September with crown rump lengths of 9.5–12.5 mm and in January with crown rump lengths of 15.2–18.7. In Salta, Argentina, a pregnant female with a well-developed fetus was reported in November ( Olrog and Barquez 1979) and in Bolivia, seven pregnant females were captured in September in the Chiquitanian Cerrado ( Siles 2007). In Peruvian Amazonia, three females with developed mammae were collected on 20 September 2005; one of which was pregnant with a single fetus with a crown rump length = 16 mm (Díaz 2011).

Figures

Fig. 1.—An adult male Cynomops planirostris from Machadinho D’Oeste, Rondônia, Brasil. Used with permission of the photographer R.L.M. Novaes.

Fig. 2.—Dorsal, ventral, and lateral views of skull and lateral view of mandible of an adult male Cynomops planirostris (CML [Colección Mamíferos Lillo, Universidad Nacional de Tucumán] 5991) from Salta Province, Río El Naranjo 14 km of road n° 5 (access to the Parque Nacional El Rey). Greatest length of skull is 16.89 mm.