Daptomys nunashae, Pacheco & Sánchez-Vendizú & Fajardo & Cossíos & Cadenillas, 2025

Daptomys nunashae sp. nov.

Tingo María fish-eating rat

Figures. 3–9 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9

Holotype. An adult female (toothwear class 5 with a fused sphenoccipital suture) preserved in 95º alcohol with skull removed, and muscle tissue preserved in alcohol 95º, deposited in the Museo de Historia Natural, Universidad Nacional Mayor de San Marcos, Lima, Peru ( MUSM 45056 ); collected by Pamela Sánchez-Vendizú on December 8, 2015 under field catalog number PSV 012.

Type locality. Parque Nacional Tingo María , Puesto de control Tres de Mayo , Mariano Damaso Beraún District , Leoncio Prado Province, Huánuco Department, Peru, at 1115 m elevation ( 9.405733° S, 76.003342° W; Fig. 1 View FIGURE 1 ) GoogleMaps .

Paratype. One male juvenile specimen ( MUSM 44669 ) from the type locality collected by Ursula Fajardo on 10 November 2014 under field catalog BIO 013 ( 9.407142° S, 76.003719° W, 1129 m) GoogleMaps .

Distribution. Daptomys nunashae is known only from Parque Nacional Tingo María, Leoncio Prado Province, Huánuco Department, Peru ( Fig. 1 View FIGURE 1 ).

Etymology. The specific epithet nunashae refers to a local legend about Princess Nunash, who was transformed into the iconic “Sleeping Beauty” Mountain (“Bella Durmiente” in Spanish), a prominent mountain surrounding the city of Tingo María. The mountain’s silhouette resembles a lying woman and is a well-known landmark in the region. The city of Tingo María is near both the type locality and the national park where the species was discovered.

Diagnosis. Daptomys nunashae is distinguished from congeners by the combination of the following characters: pelage brown chocolate, tail unicolored with a distinct pencil of white hairs, thenar of hindfeet large and swollen, gnathic process of the premaxillae well developed, nasals expanded anteriorly and tapering posteriorly, incisive foramina short, interparietal antero-posteriorly short and narrow, ectotympanic process large and overlapping the suspensory process of squamosal, orbicular apophysis absent, palate very long with prominent median process, postglenoid foramen large, lacrimal small and narrow, and toothrow small.

Morphological description. A small-sized ichthyomyine rodent (HBL: 139 mm). Body. The pelage is glossy, grizzled-dark brown chocolate and not countershaded ( Figs. 4 View FIGURE 4 , 5 View FIGURE 5 ). The hairs are long, about 10–11 mm with abundant guard hairs reaching up to 13 mm; the hair bases are gray and woolly, guard hairs are pale brown. The juvenile specimen (MUSM 44669) exhibits a small whitish patch on the ventral surface, absent in the adult. The pinnae are moderately sized ( 12.5 mm), rounded, and visible above fur; dark brown and densely haired on the internal and external surfaces. The length of the forefeet digits is arranged as follows: III> IV> II >> V >> I. The dorsal surface of metacarpals is pale brown; claws are well developed, with their bases closed, and short ungual tufts. Thenar, hypothenar, and three interdigital pads are well developed ( Fig. 6c View FIGURE 6 ). The hindfeet appear long and moderately broad, with no plantar squamation; metatarsals are pale brown. The thenar pad is large and swollen while the hypothenar pad is absent. Four large interdigital pads are present ( Fig. 4a View FIGURE 4 ). A fringe of stiff hairs is present, though moderately developed, on the medial side of pes, but absent on the lateral side of pes ( Fig. 6b View FIGURE 6 ). The length of the hindfeet digits is arranged: III> IV> II >> V> I; digit I (including claw) is long, extending near to 1st interphalangeal joint of digit II; digit V is long, the claw of digit V extends beyond the 1st interphalangeal joint of digit IV. Webbing is small between all digits. The tail is unicolored, dark brownish, and shorter than head-and-body length. It is hirsute, with 4–5 mm long hairs on both dorsal and ventral surfaces and ends in a prominent apical tuft of long white hairs ( 9–10 mm) in the adult specimen l ( Fig. 6d View FIGURE 6 ). The caudal scales are not externally visible. Most mystacial vibrissae are dense and short, with a few extending just beyond the pinnae when laid backward. Genal and superciliary vibrissae are absent. Carpal, submental, and long interramal vibrissae are present. The philtrum is present. Three pairs of mammae are present in pectoral, abdominal, and inguinal pairs.

Skull. Medium-sized and moderately robust (greatest length of skull= 26.9 to 27.3 mm in adults), with an almost flat and non-inflated braincase ( Fig. 7 View FIGURE 7 ). The rostrum is short and broad, with nasolacrimal capsules concealed from dorsal view. The nasals are long posteriorly and tapering, extending behind the fronto-maxillary suture and longer than premaxillae. The anterior third of the nasals is conspicuously expanded. The lacrimals are small, narrow, and lack a posterior process ( Fig. S1.1 View FIGURE 1 ). The interorbital region is narrow with smoothly rounded supraorbital margins that converge posteriorly in a weak-defined constriction. The supraorbital foramina are placed on the lateral surface of the frontals, within the orbital fossae. A postorbital crest is absent. The zygomatic arches are complete, slender, and subparallel. The braincase is elongated and rather subrectangular, with small lambdoid crests. The fronto-parietal suture is wedge-shaped. The interparietal bone is short antero-posteriorly and narrow ( Fig. S1.2 View FIGURE 1 ). The parietal-occipital suture is wide. The occipital condyles are produced posteriorly beyond the occiput being fully exposed in dorsal view. In lateral view, the rostrum appears low and moderately robust; the gnathic process is large and distinctly projected beyond the anterior surfaces of the upper incisors. The zygomatic plate is vertical, relatively narrow, and laterally strongly flared; the anterior margin is concave. The posterior edge of the inferior zygomatic root levels the anterocone of M1. A distinct masseteric tubercle is present on the ventral portion of the zygomatic plate. The jugal bone is slender. The optical foramen is small, oval, and distinctly posterior to M3. The alisphenoid strut is present. The carotid circulation conforms to pattern 1 as determined by Voss (1988): large stapedial foramen, squamosal-alisphenoid groove, and sphenofrontal foramen present. The postglenoid foramen is large and rounded; the subsquamosal fenestra is closed except in the juvenile specimen that exhibits a small fenestra. In ventral view, the incisive foramina are conspicuously short; their anterior halves are slightly narrower than the posterior portions and extends posteriorly well anterior to the M1 plane. The palate is long and wide (sensu Hershkovitz 1962), bearing small, simple posterolateral palatal pits on either side of the anterior margin of the mesopterygoid fossa. The mesopterygoid fossa is moderately broad with parallel sides, and its anterior margin lies well posterior to M3. A distinct median posterior palatal process is present. The sphenopalatine vacuities are absent, and the bony roof and walls of the mesopterygoid fossa are completely ossified. The parapterygoid fossa is narrow and subtriangular with a large posterior opening of the alisphenoid canal. The middle lacerate foramen is conspicuous. The ectotympanic bone exhibits a large and robust process that overlaps the suspensory process of the squamosal. The auditory bullae are slightly inflated, and the eustachian tubes relatively short and broad.A long and well-developed stapedial process overlaps the squamosal. The orbicular apophysis of the malleus is absent ( Fig. S1.3 View FIGURE 1 ). In posterior view of the skull, the dorsal margin of the foramen magnum is rounded, and the lateral margins are slightly convex ( Fig. S1.4 View FIGURE 1 ).

Teeth. The upper incisors are robust, wide, and deep, approaching the orthodont condition, with the anterior surfaces medially inclined ( Fig. 7 View FIGURE 7 ). The cutting edge of the upper incisors forms a shallow “V” shape. The upper molar series is small, delicate, and parallel; main cusps are arranged in slightly alternate pairs, with the labial cusps slightly anterior to the lingual ones; flexi and conules are conspicuous in the subadult specimen ( Fig. 8 View FIGURE 8 ). The first upper molar (M1) exhibits a distinct undivided anterocone of similar width to the paracone–protocone pair ( Fig. 8 View FIGURE 8 ). The anteroloph, mesoloph, and posteroloph are absent. In M1, the metacone–hypocone pair is subequal in width to the paracone–protocone pair, whereas the metacone–hypocone pair of M2 is narrower than the paracone–protocone pair. The protoflexus of M2 is distinct. The M3 is small and peg-like. The first lower molar (m1) exhibits a small and narrow anteroconid, the protoflexid and metaflexid are indistinct, and the anteromedian flexid is absent. The metaconid–protoconid pair is narrower than the entoconid–hypoconid pair. The mesolophid and posterolophid are absent. In m2, the metaconid–protoconid pair is subequal to the entoconid–hypoconid pair, and a tiny posterolophid is present. The m3 is peg-like ( Fig. 8 View FIGURE 8 ).

Mandible and hyoid. The mandibular bone is not deep, and the ventral surface is concave ( Fig. 7 View FIGURE 7 ). The coronoid process is well developed, falciform, and higher than the condylar process; the sigmoid notch between them is deep. The angular process extends to the condylar process plane and the sigmoid notch between them is deep. The capsular process of the lower incisor is not developed. A retromolar fossa is conspicuous. In the hyoid, the anterior margin of the basihyal is convex and lacks a medial process, while the posterior margin is concave. The tyrohyal is long and slender.

Stomach and Gall bladder. The stomach is nearly hemiglandular, with gastric glandular epithelium extending from the esophagus to the pyloric sphincter; the incisura angular is shallow. Gall bladder present ( Fig. S1.5 View FIGURE 1 ).

Measurements of holotype: HBL = 139, TL = 113, HF = 24.1, Ear = 12.5, CIL = 27.88, CML = 18.83, LOF = 10.21, LN = 10.85, LD = 7.15, LIF = 4.91, LM = 3.64, BN = 3.68, BIF = 2.07, BPB = 2.72, BM1 = 1.17, LIB = 4.72, ZB = 14.61, BB = 12.12, BZP = 1.29, BIT = 2.03, HI = 4.75, DI = 1.62, BOC = 7.07, HBC = 8.85.

Comparisons. Table 4. Species of Daptomys and Neusticomys are externally very similar, but are distinguishable by several discrete craniodental characters. Compared to Neusticomys , D. nunashae has the posterior edge of the inferior zygomatic root at level of the anterocone of M1 (versus posterior to M1); incisive foramina short (versus long); interparietal reduced (versus moderate), and occipital condyles projected backward (versus unprojected). Therefore, D. nunashae only needs further comparisons with other species of Daptomys .

Daptomys nunashae , as well as D. ferreirai , D. oyapocki , D. mussoi , and D. peruviensis , exhibits a metaconehypocone pair of M2 narrower than the paracone-protocone pair whereas in D. venezuelae this condition is subequal. Additionally, three upper molars are consistently present in D. nunashae , compared to only two in D. oyapocki , and two or three molars in D. ferreirai . Therefore, further comparisons are only required between D. nunashae and D. ferreirai , D. mussoi , and D. peruviensis .

Compared to Daptomys peruviensis , D. nunashae has the ventral pelage not countershaded (versus slightly paler) ( Figs. 3 View FIGURE 3 , 5 View FIGURE 5 ) and a distinct terminal white pencil on the tail (versus absent) ( Fig. 6D View FIGURE 6 ); the feet have a well-developed thenar and smooth plantar pes (versus moderately developed thenar and scaled plantar pes)( Fig. 6A View FIGURE 6 ); shorter incisive foramina and molar toothrow ( Figs. 7 View FIGURE 7 , 9 View FIGURE 9 ); the posterior edge of inferior zygomatic root is at level of the anterocone of M1 (versus anterior to M1); the orbicular apophysis of the malleus is absent (versus present); the palate exhibit a conspicuous posterior median process (versus small in D. peruviensis ; the M1 anterocone is barely narrower than the paracone–protocone pair (versus narrower in D. peruviensis ; also the M1 anterocone and the m1 anteroconid are undivided (versus slightly divided in D. peruviensis ) ( Fig. 8 View FIGURE 8 ).

Compared to Daptomys musseri , D. nunashae has the ventral pelage not countershaded (versus slightly paler) ( Figs. 3 View FIGURE 3 , 5 View FIGURE 5 ) and a distinct terminal white pencil on the tail (versus absent) ( Fig. 6D View FIGURE 6 ); shorter incisive foramina and molar toothrow ( Figs. 7 View FIGURE 7 , 9 View FIGURE 9 ); the posterior edge of inferior zygomatic root is at level of the anterocone of M1 (versus anterior to M1); the orbicular apophysis of the malleus is absent (versus present); the palate exhibit a conspicuous posterior median process (versus absent); the M1 anterocone is barely narrower than the paracone–protocone pair (versus narrower).

Compared to Daptomys ferreirai , D. nunashae exhibits a distinct terminal white pencil on the tail (versus absent), tapering nasals (versus subrectangular), and very short incisive foramina not close to M1 plane (versus almost reaching M1 plane); the posterior edge of inferior zygomatic root is at level of the anterocone of M1 (versus anterior to M1. Additionally, the protoflexid and metaflexid of m1 are indistinct (versus distinct).

Compared to Daptomys mussoi , D. nunashae differs in having brownish ear fur (versus cream-colored), tapering nasals (versus subrectangular), and very short incisive foramina not close to M1 plane (versus long, nearly reaching M1 alveolus), a well-developed ectotympanic process (versus absent), and an absent orbicular apophysis (versus present but small). Furthermore, D. nunashae is larger than D. mussoi in nearly all morphometric variables ( Table 2).

Natural history. The known specimens of Daptomys nunashae were collected in pitfall traps set on the right bank of a steep ravine following a prolonged an intense storm, similar to the collecting condition for D. musseri ( Pacheco et al. 2020) . The habitat ( Fig. 10 View FIGURE 10 ) is a premontane forest characterized by tall trees ( 20–25 m in height), including Nectandra longifolia ( Lauraceae ), Virola sebifera ( Myristicaceae ), and palms such as Iriartea deltoidei ( Arecaceae ). Following Britto (2017), D. nunashae inhabits Montane Rain Forest and Very Humid Montane Forest. The species was collected on the left bank of Huallaga River in sympatry with Neacomys amoenus , Neacomys macedoruizi , Monodelphis peruviana , and Euryoryzomys macconnelli .