Neacomys vargasllosai, Hurtado, Natali & Pacheco, Víctor, 2017

Hurtado, Natali & Pacheco, Víctor, 2017, Revision of Neacomys spinosus (Thomas, 1882) (Rodentia: Cricetidae) with emphasis on Peruvian populations and the description of a new species, Zootaxa 4242 (3), pp. 401-440: 418-420

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Neacomys vargasllosai

sp. nov.

Neacomys vargasllosai   , sp. nov.

Mario’s Spiny Mouse

Neacomys spinosus spinosus Lawrence, 1941:419   N [eacomys]. s [pinosus]. spinosus Hershkovitz, 1940:3   Neacomys spinosus Thomas, 1901:189  

Holotype. MUSM 35069, adult male, skin, and skull, collected on 9th May 2010 by Carlos Jiménez, original number 463.

Paratype. Seven adult specimens (MUSM 35063, 35066, 35071, 35073, 35074, 35081, and 35083) preserved as skull and skin. Selected measurements of the holotype and paratype specimens are provided in Table 4.

Type locality. Yanahuaya , Sandia, Puno, Peru, 1652 m. 14°14.5’ S, 69°10’ W ( Fig. 6 View FIGURE 6 ). GoogleMaps  

Distribution. Neacomys vargasllosai   is distributed from southern Peru, northern the Inambari River watershed in Puno, to southern Bolivia, western Santa Cruz.

Etymology. Dedicated in tribute to Mario Vargas Llosa, Peruvian writer and Nobel Prize winner in Literature 2011. Mario Vargas Llosa was born in Arequipa, Peru as N.H., and lived in Bolivia (as the current range of N. vargasllosai   ) the first years of his childhood until he returned back to Peru. He studied Laws in the Universidad Nacional Mayor de San Marcos, alma mater of V.P. and N.H.

Diagnosis. Neacomys vargasllosai   is medium sized rodent distinguished from other congeners by the combination of the following characters: dark brown dorsal fur, dull white with gray basis ventral fur, small metacarpal patch, tapering rostrum, flask-shaped bullae, convex pterygoid plate, presphenoid with concave lateral borders, antero-posteriorly convex and short mesoloph of M1, short and convex posteroloph of M1, deep protoflexus of M2, antero-posteriorly convex mesoloph of M2, straight and short posterolophid of m1, narrow anterolabial cingulum of m2, and straight posterior border of the posterolophid of m2.

Morphological description. Medium size. Dorsal fur is dark brown; soft hairs are dark brown with pale orange tips; fur length is 10 mm in average at rump level. Flanks are narrow and yellowish orange. Ventral fur is dull white, with gray roots; ventral fur length is 4 mm in average at belly level. Ungual manus tufts pass slightly the claws. Fifth digit of the forefeet passes the second interphalangeal joint of the fourth. Metacarpal patch is small, between II and III finger base, with colored scales and hairs. Carpal vibrissae pass the first interphalangeal joint of the fifth digit. Genal vibrissae do not pass the posterior border of the pinna. Mystacial and superciliary vibrissae pass the posterior border of the pinna. Interramal are inserted on basal protuberances. Hind feet are almost twice forefeet length. Ungual pedal tufts overlap claws. First pedal digit reaches the second digit base, and the fifth digit reaches the second interphalangeal joint of the fourth. Metatarsal patch is absent. Plantar squamation is restricted to the pad region. Tail is around 40 % longer than head-body length. Upper tail hairs are black and they cover 1–2.5 scales; lower hairs are whitish and cover 1.5–3 scales. Pencil present scarce long hairs.

Skull. ( Fig. 10 View FIGURE 10 ) Dorsal view. Rostrum is narrow, laterally flattened. Anterior borders of the nasals are rounded. Posterior borders of the nasals are irregularly square shaped; placed behind both premaxillary-maxillary-frontal and maxillary-frontal-lacrimal joints. Sutures between maxillary and frontal bones are large and numerous. Zygomatic notch is shallow and encloses partially the lacrimal foramen. Lacrimals are rounded; one-half is on the frontal and other in the zygomatic. Interorbital beads are poorly developed. Flanks of interparietal are not projected.

Lateral view. Skull profile is slightly convex. Rostrum presents a small hump. Gnathic anterior process is short. The most anterior part of the suture between nasal and premaxillary bones passes the squamosal root of zygomatic. Breadth of the maxillary root of zygomatic is as M3 length. Zygomatic plate breadth is subequal to the upper molar row length. Squamosal zygomatic root breadth is one-half of the zygomatic plate breadth. Ethmoid foramen is placed among the metacone of M1 to mesoloph of M2. Sphenopalatine foramen is placed at metacone of M2 level; its diameter is subequal or slightly greater than M3 length. Ethmoturbinals breadth is as M1 length. Alisphenoid strut is always absent. Tegmen tympani do not overlap the posterior process of the squamosal. Orbicular apophysis of the malleus is globose and elongate; the lamina is rectangle and shallow. Processus brevis of the incus is large, subequal to incus breadth. Internal surface of mastoid tubercle is concave. Upper border of postglenoid foramen is rounded, at subsquamosal foramen level is tapering; both foramina reach the upper border of the mastoid. Hamular process is narrow, as the orbicular apophysis breadth. Mastoid perforation is placed on the posterior border, similar to M3 length, and square shaped.

Ventral view. Inner borders of the incisive foramina borders are posteriorly convergent. Incisive foramina breadth is about as M1-M2 length. Septum of incisive foramina is narrow. Diastema is flat with a small and elongated hump, placed behind of the premaxillary-maxillary suture. Origin of the superficial masseter is ovoid and slightly protruded; it is placed behind of the anterior border of the zygomatic plate. Maxillary-palatine suture is at hypoflexus level of M1. Posterior palatine foramina are at the hypocone level of M1. Posterolateral palatal pits are placed anterior to the mesopterygoid border level. Sphenopalatine vacuities are open around basisphenoid and presphenoid. Presphenoid is laterally compressed with concave lateral borders. Mesopterygoid fossa breadth is lesser than the incisive foramina breadth. Parapterygoid processes are parallel; laterally, they pass the molar surface level. Borders of the pterygoid plate are convex. Fontanellae are tiny but distinguishable. The posterior opening of the alisphenoid canal breadth is as M3 length. Groove of the infraorbital branch of the stapedial artery is shallow.

Middle lacerate foramina width is as M3 length. Eustachian tube is short and broad. Bullae are flask-shaped. Anterior bulla process and the pterygoid plate are not in contact. Basioccipital breadth at petrosal level is subequal to breadth between second upper molars. Basioccipital pits are shallow. Anterior border of the foramen magnum is obtuse V-shaped with a moderate notch.

Jaw. Masseteric crest is below the procingulum of the m1. Mental foramen is at the labial border of the diastema. Capsular process is moderately developed but does not pass the condylar process. Coronoid process is slightly thin. Condylar process is large and thin. Angular process is short. Crest between condylar and angular process is rounded and shallow. Ventral border of the jaw is concave.

Teeth. Upper. Incisors are opisthodont, with rounded tips and yellow-orange enamel bands. Molar rows are parallel. Procingulum of M1 is anteriorly flattened, narrow and symmetrically divided. Anteroflexus of M1 does not reach the labial surface. Mesoloph of M1 is antero-posteriorly convex and does not reach the labial surface. Posteroloph of M1 does not reach to the labial surface; posterior border is convex. Anteroloph of M2 is broad and reaches the labial surface. Protoflexus of M2 is deep. Mesoloph of M2 is antero-posteriorly convex to the labial surface. Posteroloph of M2 reaches the molar surface. Posterior border of the posteroloph of M2 is rounded. Anteroloph of M3 reaches the paracone surface. Lower. Procingulum of m1 is symmetrically divided. Mesolophid of m1 is narrow. Hypoflexid of m1 is perpendicular to the labial surface. Posterior border of the posterolophid of m1 is straight, and does not reach the lingual surface. Anterolabial cingulum of m2 is narrow. Posterior border of posterolophid of m2 straight and does not reach the lingual surface.

Remarks. Thomas (1901) reported this species from Inambari River ( Peru) to Mapiri and Perené rivers ( Bolivia), but not specified additional information. Pacheco et al. (2011) recorded populations of N. vargasllosai   sp. nov. as N. spinosus in Challohuma   (1200 m) and Yanacocha (1985 m); both localities present yields of citrus fruits, and are placed in the vicinities of the Parque Nacional Bahuaja Sonene ( Peru). Adult males with scrotal testis were found from 9 to 21 May 2010. In the same period, female specimens with perforated and non-perforated vagina were found, but none pregnant or lactating. There is not additional information about the biology of this species.

TABLE 4. Measurements of the type series of Neacomys vargasllosai sp. nov. from Sandia, Puno, Peru. The number in the column heading is the MUSM catalogue number. Age and sex are in parentheses, f = female, m = male.

  Holotype 35069 (II, m)              














Neacomys vargasllosai

Hurtado, Natali & Pacheco, Víctor 2017

Neacomys spinosus spinosus

Lawrence 1941: 419
Hershkovitz 1940: 3
Thomas 1901: 189