Cryptotis aroensis, Quiroga-Carmona, Marcial & Molinari, Jesús, 2012

Quiroga-Carmona, Marcial & Molinari, Jesús, 2012, Description of a new shrew of the genus Cryptotis (Mammalia: Soricomorpha: Soricidae) from the Sierra de Aroa, an isolated mountain range in northwestern Venezuela, with remarks on biogeography and conservation, Zootaxa 3441, pp. 1-20 : 3-11

Cryptotis aroensis , new species

Sierra de Aroa shrew

Holotype. CVULA I–8548, an adult male ( Fig. 1 A, 1B), with complete skull and mandibles ( Figs. 2 and 3 ) plus ethanol-preserved body, collected on March 12, 2011. Measurements in Table 1.

Type locality. Las Cumaraguas Sector, Sierra de Aroa, Municipio Cocorote, Estado Yaracuy, Venezuela (10°22'02.6''N, 68°49'20.4'W), elevation 1730 m. This site is a pristine patch of cloud forest near a dirt road and around a small creek ( Fig. 4 ). See Map ( Fig. 5 ).

Paratypes. CVULA I–8546, an adult female, collected on March 8, 2011 (right hindfoot shown in Fig. 1 ; dentition in Fig. 3 ). CVULA I–8547, an adult male, collected on March 12, 2011 (dentition shown in Fig. 3 ). Both obtained in the type locality, and prepared as skulls and mandibles (which are in good conditions, except for the left angular process which is broken in CVULA I–8546) plus ethanol-preserved bodies. Measurements in Table 1.

Etymology. The species name aroensis [Aro(a) + ensis] is a toponym meaning “from Aroa.”

Diagnosis. A member of the C. thomasi group (for characters defining this group, see Choate 1970; Woodman et al. 2003; and below in description). Pelage rich grayish brown. Pinnae almost as broad as high, and therefore visible frontally. Anterior border of zygomatic plate in line and above the metastyle of M1, and posterior border in line and above the paracone of M3. Palate at the level of the second molars narrower than that of any other known member of the C. thomasi group (M2B averaging 5.5 mm; Table 1). In occlusal view of the posterior palate, a small part of the nasal cavity and the ethmo-turbinals can be observed at each side of the vomer, which is the only bone of the roof of the mesopterygoid fossa penetrating the choanae. Lacrimal foramina wide and deep. A minute foramen on the posterior edge of the tympanic process of each petromastoid. U1, U2, and U3 with posterolingual cuspules. U4 small to medium-sized for a member of the C. thomasi group. U4 labially placed, thus U4 visible in lateral view. Upper molars conspicuously pigmented. M3 complex, and nearly as wide as M2. Bicuspulate lower incisors, each with a poorly developed, almost imperceptible, anterior cusp separated from the posterior cusp by a shallow anterior notch.

Description. External and craniodental measurements, and body masses of the holotype, and the 2 paratypes, are shown in Table 1.

External characters ( Fig. 1 ).—A medium-sized and long-tailed member of the C. thomasi group (mean HB> 72 mm is a diagnostic character for members of the C. thomasi group; Woodman et al. 2003), HB averaging 79.0 mm, and tail averaging 46% of HB (Table 1). General coloration rich grayish brown. Long (about 6–7 mm), luxuriant fur (a diagnostic character for members of the C. thomasi group; Woodman et al. 2003). Hairs bicolored, with gray bases and brown tips. Dorsal pelage darker and brighter than ventral pelage, but lacking a clear dorsoventral demarcation. Tail unicolored. Muzzle with 8 or 9 pairs of postnasal warts, and with mystacial vibrissae reaching the ears. Upper half of philtrum with a smooth, long and narrow wart. Pinnae moderately long (standard ear length, which measure height, averaging 6.8 mm; Table 1) and broad (projecting about 6 mm laterally), each with a laterally well-developed helix, antihelix and antitragus, and deep scapha. Flanks of body without noticeable bare patches marking the location of lateral glands (a diagnostic character for members of the C. thomasi group; Woodman et al. 2003). Forefeet somewhat enlarged (a diagnostic character for members of the C. thomasi group; Woodman et al. 2003), robust, covered by abundant short hair, and having long central digits. Foreclaws, not broadened, relatively straight, and elongated (a diagnostic character for members of the C. thomasi group; Woodman et al. 2003). Forefeet and hindfeet with moderately developed and circular thenar and hypothenar eminences, and palmar pads. Thenar eminences slightly more distal than hypothenar eminences ( Fig. 1 C). Digits with moderately developed, granular, and juxtaposed scales arranged in 2 longitudinal rows ( Fig. 1 C). Tail covered with short and coarse hairs, and with small scales (averaging 32 per cm) lacking sharp edges.

Cranial and mandibular characters ( Fig. 2 ).—Nasal openings narrow (rectangular-shaped in occlusal view), fully encased laterally by the premaxillary bones. In occlusal view, zygomatic plate with its anterior border in line and above the metastyle of M1, and its posterior border in line and above the paracone of M3. Palate short (PL averaging 9.1 mm; Table 1), and very narrow at the level of M2 (M2B averaging 5.5 mm; Table 1). Posterior branch of maxillary process aligned over the mesostyle of M3, and not in touch with the posterior border of palate. Lacrimal foramina wide and deep. Apertures formed by the combined foramen rotundum and inferior orbital fissure of each side ( Gaughran 1954) wide and ovoid, located posteriorly on alisphenoids. Ovale foramina wide. The vomer is the only portion of the roof of the mesopterygoid fossa penetrating the choanae, thus, in occlusal view, a small part of the nasal cavity and the ethmo-turbinals can be observed at each side of the vomer ( Fig. 3 ). Petromastoids each with a short, thin, and low anterior process. Posterior border of tympanic processes of petromastoids each with a minute foramen that is posterior in position to the paraoccipital process. Mandibles long (averaging 7.3 mm; Table 1), short behind m3 (AC3 averaging 5.1 mm; Table 1). Coronoid processes low (a diagnostic character for members of the C. thomasi group; Woodman et al. 2003), wide, and straight. Articular processes high, broad, and not robust (a diagnostic character for members of the C. thomasi group; Woodman et al. 2003). Upper sigmoid notches angled. Lower sigmoid notches shallow to very shallow (a diagnostic character for members of the C. thomasi group; Woodman et al. 2003).Angular processes straight, short (not surpassing posteriorly the condyle), broad at base, and blunt-tipped.

Dental characters ( Figs. 2 and 3 ).—Teeth robust (nonbulbous). U1, U2, and U3 relatively narrow, and concave to very concave on the posteroventral margin (a diagnostic character for members of the C. thomasi group; Woodman et al. 2003). U1, U2, and U3 with well-developed cuspules. U1, U2, U3, and U4 with low and broad cingula, and dark red cusps. U4 small to medium-sized for a member of the C. thomasi group, of approximately circular contour in occlusal view, and labially placed, thus, if cranium is rotated sideways as necessary, U4 visible in lateral view. P4 with an anteriorly well developed and well pigmented parastyle, and a well pigmented protocone. M1 with the anterior element of ectoloph shorter than the posterior element (a diagnostic character for members of the C. thomasi group; Woodman et al. 2003). M1 and M2 having well-developed and intensely pigmented protocones, little developed and unpigmented hypocones, and precentrocristae and postcentrocristae with fully developed and very high labial sides. M3 complex (mesostyle, postcentrocrista, and metacone conspicuous), and nearly as wide as M2. Bicuspulate lower incisors with dark red terminal halves, each with a poorly developed, almost imperceptible, anterior cusp separated from posterior cusp by a shallow anterior notch. Lower molars as follows: m1 and m2 with well-developed and pigmented entoconids and hypoconids; m3 having an elongated talonid, a high and pigmented hypoconid, and a high and posteriorly well-developed hypoconulid.

Distribution. Known only from the type locality ( Fig. 5 ). Cryptotis aroensis is most likely an endemic species to the highlands of the Sierra de Aroa, in northwestern Venezuela.

Comparisons. The morphometric values to which we refer in the comparisons are taken from Table 1, and from the sources mentioned above (Materials and methods). In the comparisons, we enumerate as morphometric differences only measurements whose means are significantly different (in each case we indicate p -values) between the new species and other members of the C. thomasi group.

There is 1 unique distinguishing character of C. aroensis that, for the sake of brevity, we do not repeat in the comparisons that follow. Namely, the species has a very narrow palate at the level of molars, i.e., the mean value of M2B of C. aroensis is significantly (p <0.01, or p << 0.01, depending on the species) smaller than the M2B values of all other species of the C. thomasi group, with the exception of C. peruviensis , of which only 2 specimens are known (M2B is smaller but p is not significant). Moreover, the individual M2B values of the 3 specimens of C. aroensis (Table 1) fall below the range of the individual M2B values of the 146 specimens of the 10 species (including C. peruviensis , and C. squamipes ) of the C. thomasi group for which cranial measurements are available (for the M2B value of the holotype of C. squamipes , see Allen 1912).

Comparison with Cryptotis sp. A Quiroga-Carmona, in press. – Cryptotis aroensis differs from this species, which occurs in the Venezuelan Cordillera de la Costa ( Fig. 5 ), in having: 1) pelage rich grayish brown (as opposed to dark gray with a dark brown luster); 2) better developed pinnae that are nearly as broad as high, thus visible frontally, each with a laterally well-developed helix, antihelix and antitragus, and deep scapha (as opposed to pinnae that are higher than broad, thus hidden in pelage, each with scarcely developed helix, antihelix, and antitragus, and a superficial scapha); 3) muzzle with a long and narrow wart restricted to the upper half of philtrum (as opposed to a long and narrow wart extending from the edge of the upper lip to the base of the rhinarium); 4) muzzle with 8 or 9 pairs of postnasal warts (as opposed to 4 pairs); 5) digits robust, with poorly developed, semisquare, and juxtaposed scales, arranged in 2 longitudinal rows (as opposed to digits delicate, with well-developed, granular, and juxtaposed scales, arranged in 3 longitudinal rows); 6) tail scales smaller, averaging 32 per cm (as opposed to larger, averaging 26 per cm); 7) in occlusal view, anterior margin of the mesopterygoid fossa covered by the palatine extension of the hard palate only centrally (as opposed to anterior margin of the mesopterygoid fossa completely covered by the palatine extension of the hard palate); 8) U4 visible in lateral view if cranium is rotated sideways as necessary (as opposed to U4 not visible in lateral view, even if rotated sideways); 9) M3 about as wide as M2 (as opposed to narrower than M2); 10) lower incisors with a well defined, albeit shallow, anterior notch (as opposed to with an almost imperceptible anterior notch); 11) coronoid processes slightly higher than condyles (as opposed to much higher than condyles); 12) angular processes narrow-tipped (as opposed to broadtipped).

Comparison with Cryptotis meridensis ( Thomas, 1898) , and Cryptotis tamensis Woodman, 2002 .– Cryptotis aroensis differs from either or both species ( C. meridensis occurs in the Venezuelan Cordillera de Mérida, and C. tamensis occurs in the Colombian Cordillera Oriental, and adjacent Venezuelan Andes, namely in the Páramo del Tamá; Fig. 5 ) in having: 1) head-and-body shorter (p << 0.01), HB averaging 79.0 mm (as opposed to head-andbody longer, HB averaging 86.0 mm, in C. tamensis ); 2) pelage rich grayish brown (as opposed to dark gray or gray, with a brownish luster, in C. meridensis ; and to chocolate-brown, in C. tamensis ); 3) better developed pinnae that are nearly as broad as high, thus visible frontally, each with a laterally well-developed helix, antihelix and antitragus, and deep scapha (as opposed to pinnae that are higher than broad, thus hidden in pelage, each with scarcely developed helix, antihelix, and antitragus, and a superficial scapha); 4) muzzle with a long and narrow wart restricted to the upper half of philtrum (as opposed to upper half of philtrum with a very short wart in contact with the rhinarium); 5) muzzle with 8 or 9 pairs of postnasal warts (as opposed to 4 or 5 pairs); 6) digits robust, with poorly developed, semi-square, and juxtaposed scales (as opposed to delicate, with well-developed, granular, and juxtaposed scales); 7) tail scales smaller, averaging 32 per cm (as opposed to larger, averaging 30 per cm); 8) lacrimal foramina wide and deep (as opposed to very narrow and shallow); 9) in occlusal view, anterior margin of the mesopterygoid fossa covered by the palatine extension of the hard palate only centrally (as opposed to anterior margin of the mesopterygoid fossa completely covered by the palatine extension of the hard palate); 10) palate shorter (p <0.03), PL averaging 9.1 mm (as opposed to longer, PL averaging 9.5 mm, in C. tamensis ); 11) palate narrower at the level of the third unicuspid (p <0.03), U3B averaging 3.2 mm (as opposed to broader, U3B averaging 3.5–3.7 mm); 12) U4 small to medium-sized and visible in lateral view if cranium is rotated sideways as necessary (as opposed to extremely reduced or absent, and not or little visible in lateral view when present, even if rotated sideways, in C. meridensis ); 13) M3 complex, and as wide as M2 (as opposed to simple in most specimens, and narrower than M2, in C. meridensis ; and simple or complex, and narrower than M3, in C. tamensis ); 14) lower incisors bicuspulate, each with an almost imperceptible anterior cusp separated from the posterior cusp by a shallow anterior notch (as opposed to a well-developed anterior cusp separated from the posterior cusp by a deep anterior notch); 15) m1 and m2 with well-developed and pigmented entoconids (as opposed to m1 and m2 with low entoconids showing pigmentation only on tips); 16) m3 having an elongated talonid, a high hypoconid, and a conspicuous hypoconulid (as opposed to a short talonid, and a medium hypoconid in C. meridensis and C. tamensis ; no hypoconulid in C. meridensis ; a reduced hypoconulid in C. tamensis ); 17) angular processes short (not surpassing posteriorly the condyle), broad at base, straight, and blunt tipped (as opposed to long and narrow).

Comparison with Cryptotis thomasi ( Merriam, 1897) .— Cryptotis aroensis differs from this species, which occurs near Bogotá, in the central part of the Colombian Cordillera Oriental, in having: 1) tail longer (p << 0.01), TL averaging 36.3 mm (as opposed to shorter, TL averaging 24.0 mm); 2) pelage rich grayish brown (as opposed to brown); 3) a minute foramen on the posterior edge of the tympanic process of each petromastoid (as opposed to a large foramen on the same position); 4) posterior border of zygomatic plate in line and above the paracone of M3 (as opposed to above or slightly behind the M2–M3 border); 5) mandible shorter behind m3 (p << 0.01), AC3 averaging 5.1 mm (as opposed to longer, AC3 averaging 5.7 mm); 6) upper sigmoid notch of each mandible semicircular, and much deeper than coronoid process and condyle (as opposed to upper sigmoid notch irregularlyshaped, and slightly deeper than coronoid process and condyle); 7) angular processes short (not surpassing posteriorly the condyle), and broad at base (as opposed to long and narrow).

Comparison with Cryptotis medellinius Thomas, 1921 .— Cryptotis aroensis differs from this species, which occurs in the northern parts of the Colombian Cordillera Central and Cordillera Occidental, in having: 1) body mass lower (p <0.02), BM averaging 11.0 g (as opposed to higher, BM averaging 16.2 g); 2) pelage rich grayish brown (as opposed to light brown); 3) a minute foramen on the posterior edge of the tympanic process of each petromastoid (as opposed to a huge foramen on the same position); 4) anterior border of zygomatic plate in line and above the metastyle of M1, and posterior border in line and above the paracone of M3 (as opposed to anterior border of zygomatic plate at the level of the metacristae of M1, and posterior border above the metacristae or metastyle of M2); 5) forehead narrower (p <0.04), IO averaging 5.0 mm (as opposed to broader, IO averaging 5.4 mm); 6) palate shorter (p <0.04), PL averaging 9.1 mm (as opposed to longer, PL averaging 9.8 mm); 7) unicuspid toothrow shorter (p <0.01), UTR averaging 2.7 mm (as opposed to longer, UTR averaging 3.0 mm; 8) U4 small to medium-sized, and labially placed, thus U4 visible in lateral view (as opposed to U4 reduced and lingually displaced, with U3 and M1 almost in touch labially, thus U4 barely visible in lateral view).

Comparison with Cryptotis squamipes ( J. A. Allen, 1912) .— Cryptotis aroensis differs from this species, which occurs in Colombia (southern parts of the Cordillera Central and Cordillera Occidental, and Cordillera del Sur), in having: 1) external and cranial measurements (Table 1) apparently lesser (comparable measurements of the holotype of C. squamipes are: HB, 86; TL, 42; HL, 18, PL, 9.8; MTR, 6.0; M2B, 6.0; Allen 1912); 2) pelage rich grayish brown (as opposed to blackish or dark grayish brown; Allen 1912); 3) U1, U2, and U3 with posterolingual cuspules (as opposed to U1, U2, and U3 usually lacking posterolingual cuspules; Woodman & Péfaur 2008); 4) U4 labially placed (as opposed to U4 lingually displaced; photograph of the holotype); 5) coronoid process lower, HCP/ML averaging 64% (as opposed to higher, HPC/ML averaging 71%; Table 1, Woodman & Péfaur 2008).

Comparison with Cryptotis equatoris equatoris ( Thomas, 1912) , and C. e. osgoodi ( Stone, 1914).– Cryptotis aroensis differs from either or both taxa, which occur in the central Ecuadorian Andes, in having: 1) pelage rich grayish brown (as opposed to dark chocolate brown); 2) a minute foramen on the posterior edge of the tympanic process of each petromastoid (as opposed to absence of such foramen); 3) anterior border of zygomatic plate in line and above the metastyle of M1, and posterior border in line and above the paracone of M3 (as opposed to anterior border of zygomatic plate at metacristae and slightly anterior to metastyle of M1, and posterior border behind the M2–M3 border); 4) longer cranium (p <0.01), CBL averaging 21.3 mm (as opposed to shorter, CBL averaging 20.7 in C. e. osgoodi); 5) cranium broader (p <0.04), CB averaging 10.6 mm (as opposed to narrower, CB averaging 9.9 mm, in C. e. osgoodi); 6) zygomatic plate narrower (p <0.03), ZP averaging 1.9 mm (as opposed to broader, CB averaging 2.2 in C. e. equatoris ); 7) palate anteriorly broader (p <0.01, both for U1B and U3B), U1B averaging 2.8 mm, and U3B averaging 3.2 mm (as opposed to narrower, U1B averaging 2.4 mm, and U3B averaging 2.9 mm, in C. e. osgoodi); 8) upper molars conspicuously pigmented (as opposed to almost entirely white owing to absence of red pigment on hypoconal basins); 9) upper toothrow longer (p <0.03), TR averaging 8.5 mm (as opposed to shorter, TR averaging 7.9–8.0 mm); 10) lower incisors bicuspulate, with an almost imperceptible anterior cusp (as opposed to tricuspulate); 11) coronoid process higher (p << 0.01), HCP averaging 4.7 mm (as opposed to lower, HCP averaging 4.2 mm in C. e. osgoodi); 12) coronoid valley higher (p << 0.01), HCV averaging 3.2 mm (as opposed to lower, HCV averaging 2.8 mm); 13) articular condyle much higher (p << 0.01), HAC averaging 4.2 mm (as opposed to much lower, HAC averaging 2.6–2.7 mm); 14) lower sigmoid notch deep (as opposed to shallow, or moderately deep); 15) m3 with both hypoconid and hypoconulid on talonid (as opposed to with only hypoconid).

Comparison with Cryptotis montivagus ( Anthony, 1921) .— Cryptotis aroensis differs from this species, which occurs in the southern Ecuadorian Andes, in having: 1) pelage rich grayish brown (as opposed to medium gray, with a speckled appearance); 2) a minute foramen on the posterior edge of the tympanic process of each petromastoid (as opposed to absence of such foramen); 3) anterior border of zygomatic plate in line and above the metastyle of M1, and posterior border in line and above the paracone of M3 (as opposed to anterior border of zygomatic plate vertically oriented and above metacristae of M1, and posterior border above the M2–M3 contact); 4) upper molars conspicuously pigmented (as opposed to almost entirely white owing to absence of red pigment on hypoconal basins); 5) U4 labially placed (as opposed to in line with other unicuspids); 6) articular condyle much higher (p << 0.01), HAC averaging 4.2 mm (as opposed to much lower, HAC averaging 3.0 mm); 7) lower incisors bicuspulate, with an almost imperceptible anterior cusp (as opposed to conspicuously tricuspulate); 8) m3 with both hypoconid and hypoconulid on talonid (as opposed to only hypoconid).

Comparison with Cryptotis peruviensis Vivar, Pacheco and Valqui, 1997 .— Cryptotis aroensis differs from this species, which occurs in the northern Peruvian Andes, in having: 1) pelage rich grayish brown (as opposed to dark grayish brown); 2) nasal openings narrow, fully encased laterally by the premaxillary bones (as opposed to broad, partially encased laterally by the premaxillary bones); 3) a minute foramen on the posterior edge of the tympanic process of each petromastoid (as opposed to absence of such foramen); 4) posterior border of zygomatic plate in line and above the paracone of M3 (as opposed to posterior border of zygomatic plate above M3); 5) U4 approximately circular in occlusal view, and labially placed, thus U4 visible in lateral view (as opposed to U4 triangular in occlusal view, and lingually displaced, with U3 and M 1 in touch labially, thus U4 usually not visible in lateral view); 6) lower incisors bicuspulate, with an almost imperceptible anterior cusp (as opposed to conspicuously tricuspulate); 7) coronoid process relatively straight (as opposed to flared to labial side of mandible); 8) articular condyle much higher (p <0.01), HAC averaging 4.2 mm (as opposed to much lower, HAC averaging 2.9 mm); 9) angular process short and broad at base (as opposed to long and slender).

Remarks. Sexual dimorphism is not apparent in our small series of Cryptotis aroensis . This is consistent with observations made on larger samples of C. meridensis and C. tamensis ( Durant & Péfaur 1984; Woodman 2002).

Figures

FIGURE 1. External appearance of Cryptotis aroensis. A, lateral view of the holotype (CVULA I – 8548), which had a headand-body length of 81 mm, and a tail length of 40 mm (Table 1); B, ventral view of the holotype; C, ventral view of the right hindfoot of a paratype (CVULA I – 8546), which had a length of 13 mm (Table 1). Photographs by J. Molinari.

FIGURE 2. From top to bottom, dorsal, ventral, and lateral views of crania, and lateral view of mandible of the holotype (CVULA I – 8548) of Cryptotis aroensis.

FIGURE 3. Occlusal view of the upper (right) and lower (left) dentitions showing variation in 3 specimens of Cryptotis aroensis. A, views of the holotype (CVULA I – 8548); B, views of the paratype CVULA I – 8546; C, views of the paratype CVULA I – 8547.

FIGURE 4. Cloud forest at the type locality of Cryptotis aroensis; left, forest edge viewed from road; right, understory vegetation. Photographed by J. Molinari on March 12, 2011.

FIGURE 5. Map of Western Venezuela and adjacent Colombia showing collection localities of specimens of small-eared shrews examined in the present study. Areas shaded in gray indicate elevations from 1000 to 2000 m. Areas shaded in green indicate elevations above 2000 m. Species symbols are: Cryptotis aroensis (star), Cryptotis sp. A (inverted triangles), C. meridensis (solid circles), C. tamensis (triangle), and Cryptotis sp. from Sierra de Perijá (solid squares).