Otonyctomys hatti Anthony, 1932
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publication ID |
https://doi.org/ 10.1644/825.1 |
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persistent identifier |
https://treatment.plazi.org/id/96161403-FF9E-1955-A1E8-B0EF8866FEA2 |
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Carolina |
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scientific name |
Otonyctomys hatti Anthony, 1932 |
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Otonyctomys hatti Anthony, 1932
Yucata´n Vesper Mouse
Otonyctomys hatti Anthony, 1932:1 . Type locality ‘‘ Chichen Itza , Yucatan, Mexico.’’
CONTEXT AND CONTENT. Context as above. Otonyctomys hatti is monotypic.
mouse ( Nyctomys sumichrasti ), but its pelage is brighter russet ( Anthony 1932). The most conspicuous character separating O. hatti from the genus Nyctomys is the size of auditory bulla, which is up to 3 times larger than that of N. sumichrasti ( Anthony 1932) . Overall, O. hatti is consistently smaller in most cranial measurements than N. sumichrasti , except breadth and depth of braincase, which are larger due to the effect of inflated bullae ( Genoways et al. 2005). Cheek teeth and maxillary toothrow are noticeably smaller in O. hatti ( Anthony 1932; Hall 1981); differences in toothrow size can be detected by direct observation without measurement ( Genoways et al. 2005). External measurements are generally NOMENCLATURAL NOTES. Otonyctomys hatti is called Yucata´ n vesper mouse in English, and Chó’ in Mayan ( Navarro et al. 1990). Otonyctomys is from the Greek otos meaning ears, nyktos meaning night, and mys meaning mouse (Alvarez- Castan˜ eda and Alvarez 1996). The specific epithet hatti is a patronym for Robert T. Hatt, who collected the 1st specimen ( Anthony 1932).
DIAGNOSIS
Otonyctomys hatti ( Fig. 1 View Fig ) is almost identical in external characters to the closely related Central American vesper
similar, but hind foot is narrower than in N. sumichrasti ( Anthony 1932; Hall 1981).
GENERAL CHARACTERS
Otonyctomys hatti is a medium-sized, brightly colored mouse. Ears are of medium size, well covered with hair at the base but otherwise mostly naked ( Anthony 1932). Pelage of upperparts is nearly uniform bright russet to hazel, with the darkest tone on the back; sides are tawny to ochraceous tawny; individual hairs of upperparts are blackish slate at base and lighter apically; pelage of venter is white or creamy from base to tip of hairs; dark facial spots present anterior to eyes and at the base of whiskers; upper side of feet whitish washed with buff or tawny tones ( Anthony 1932; Hall 1981; Peterson 1966). The tail is well furred with individual hairs that increase in length from base to tip of tail; pelage of tail is bone-brown both above and below ( Anthony 1932). There are 2 pairs of inguinal mammae ( Anthony 1932).
No sexual dimorphism is apparent from available specimens. External measurements (means, ranges in parentheses, in mm or g) of 9– 14 adult individuals of both sexes were: total length, 201.9 (163–231); length of body and head, 100.6 (90–116); length of tail, 102.6 (60–127); length of hind foot, 21.3 (18–23); length of ear, 15.0 (13–20); and body mass, 29.0 (23–36— Anthony 1932; Aranda et al. 1997; Genoways et al. 2005; Herna´ndez-Huerta et al. 2000; Jones et al. 1974; Peterson 1966; Rick 1965; Vargas-Contreras et al. 2004). External measurements (in mm or g) of 3 juveniles from Guatemala and Quintana Roo were: total length, 157, 130, 160; length of body and head, 72, 65, 75; length of tail, 85, 65, 85; length of hind foot, 20, 18, 10; length of ear, 11, 10, 14; and body mass, 13, 5.5, 10 ( Aranda et al. 1997; Peterson 1966; Rick 1965).
Rostrum is relatively short; auditory bullae are disproportionally large and occupy most of the basicranial region ( Fig. 2 View Fig ); zygomatic arch is compressed rather than flaring; anterior margin of zygomatic plate approximately perpendicular to palatal plane; mandible is delicate with a low coronoid process and a weak ascending ramus; cheek teeth are noticeably small ( Anthony 1932; Hall 1981). Skull measurements (means, ranges in parentheses, in mm) of 3– 9 adult specimens were: greatest length of skull, 28.3 (26.8– 29.5); condylobasal length, 26.5 (24.4–28.5); length of nasals, 9.0 (8.4–9.3); zygomatic breadth, 15.1 (14.4–16.2); least interorbital breadth, 5.2 (5.0–5.5); breadth of braincase, 13.7 (13.1–14.3); depth of braincase, 11.7 (11.5–12.0); length of rostrum, 9.3 (8.8–9.8); breadth of rostrum, 5.0 (4.8–5.2); mastoid breadth, 13.7 (13.0–14.5); length of palatal bridge, 4.3 (3.9–4.6); length of upper toothrow, 4.2 (3.8–4.4); length of lower toothrow, 4.2 (4.0–4.4); length of incisive foramen, 4.6 (4.4–5.1); length of auditory bulla, 8.5 (8.0–9.5); and breadth of auditory bulla, 6.9 (6.6–7.9— Anthony 1932; Aranda et al. 1997; Genoways et al. 2005; Herna´ndez- Huerta et al. 2000; Jones et al. 1974; Peterson 1966; Rick 1965).
DISTRIBUTION
Otonyctomys hatti is endemic to the Yucatan Peninsula ( Fig. 3 View Fig ). The range of O. hatti includes northeastern Guatemala, central and northern Belize, and most of the
auditory bullae ( Genoways et al. 2005; Peterson 1966). Dental formula is i 1/1, c 0/0, p 0/0, m 3/3, total 16.
ONTOGENY AND REPRODUCTION
Individuals of Otonyctomys hatti may be separated into 3 age classes (juvenile, subadult, and adult) based on tooth wear, cranial measurements, and body measurements. Breeding may occur in 2 peaks during summer and winter. At Chiche´n-Itza´, females with enlarged uteri were captured in October and July ( Hatt 1938; Jones et al. 1974); a lactating female was present in February in Quintana Roo ( Aranda et al. 1997).
(m). Modified from Genoways et al. 2005.
Mexican states of Campeche, Yucatan, and Quintana Roo ( Genoways et al. 2005; Hall 1981). O. hatti mouse has been recorded at only 10 localities: Chichén-Itzá, Yucatan; Calakmul, Conhua´s, Esca´rcega region, and Dzibalchén, Campeche; Rancho Las Palmas and Reserva Ecolo´gica El Ede´n, Quintana Roo; Cayo District and Rockstone Pond, Belize; and Tikal, Guatemala ( Anthony 1932; Aranda et al. 1997; Genoways et al. 2005; Herna´ndez-Huerta et al. 2000; Jones et al. 1974; Laurie 1953; Peterson 1966; Rick 1965; Vargas-Contreras et al. 2004). Elevational range of known localities is sea level to 250 m.
FOSSIL RECORD
Remains of Otonyctomys hatti are from Pleistocene deposits in caves Lara, Has, Loltu´ n, Coyok, Chacaljas, and Spukil in Yucatan, Mexico. The largest number of remains correspond to cave Spukil, where 18 mandibles, 2 upper toothrows, and other fragments were recovered ( Hatt et al. 1953).
FORM AND FUNCTION
Pelage of juvenile individuals is duller in color and lacks the glossiness of the adults ( Rick 1965). The skull of Otonyctomys hatti is characterized by the greatly inflated
ECOLOGY AND BEHAVIOR
Otonyctomys hatti occurs in mature semideciduous tropical forests that are relatively open ( Aranda et al. 1997; Genoways et al. 2005; Herna´ndez-Huerta et al. 2000; Vargas-Contreras et al. 2004), and vegetation near cenotes (water-filled sinkholes— Jones et al. 1974). In Belize, vesper mice were restricted to the broad-leafed forests of the northern plains and watersheds of rivers ( McCarthy 1998).
Otonyctomys hatti seems to have strongly arboreal habits. It has been trapped on dead logs ( Genoways et al. 2005), in trees (Herna´ndez-Huerta et al. 2000; Jones et al. 1974), on lianas ( Peterson 1966), and from the top of a coconut palm ( Peterson 1966), usually at 1–2 m from the ground. In Reserva de la Biofera Ria Lagartos, Yucatan, 1 individual was observed in June 2005 using an abandoned nest of a woodpecker in a dead tree at 1.8 m from the ground (J. Chable´, pers. comm.).
Otonyctomys hatti also is found in human-made structures. Two individuals were trapped between the thatch and wall of a guest house at Chiche´n-Itza´ ( Anthony 1932); 1 was taken on a rafter under the roof of a house in Campeche ( Jones et al. 1974); and 1 in the main station building La Sabana of Reserva Ecolo´ gica El Ede´n, Quintana Roo ( Aranda et al. 1997). The individuals from Tikal were probably collected from the thatched wooden houses in the camp ( Rick 1965). In June 2002, 2 individuals were observed on a rafter under the roof of a house at cenote Lucero (16 km road Cancun–Puerto Morelos, Quintana Roo —J. Chable´, pers. comm.).
Otonyctomys hatti feeds on seeds on the ground or in shrubs ( McCarthy 1993) and probably also on soft-bodied fruits ( Genoways et al. 2005). O. hatti has been caught in the same trap lines with other species of rodents including Heteromys gaumeri , Oryzomys melanotis , Ototylomys phyllotis , and Peromyscus yucatanicus ( Genoways et al. 2005; Hatt 1938). Competition between O. hatti and N. sumichrasti might occur in a small area of Belize considering the similar size of these 2 highly arboreal mice and their reliance upon fruit in y Recursos Naturales 2002). Although this species might not be under risk of extinction, evaluation of its current conservation status is warranted (Jua´rez 2005).
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