Research Article |
Corresponding author: Thomas E. Lee Jr. ( leet@acu.edu ) Academic editor: Clara Stefen
© 2022 Thomas E. Lee Jr., Nicolás Tinoco, Jorge Brito.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Lee Jr. TE, Tinoco N, Brito J (2022) A new species of Andean mouse of the genus Thomasomys (Cricetidae, Sigmodontinae) from the eastern Andes of Ecuador. Vertebrate Zoology 72: 219-233. https://doi.org/10.3897/vz.72.e78219
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We name and describe a new species of Andean mouse from the eastern slope of the Andes of central Ecuador (Sangay National Park). This rodent is large-bodied (head-body length 167–184 mm) inhabiting the wet montane forest between 3,400–3,900 m in elevation. A molecular phylogeny based on mitochondrial genes resolved the new species as a member of the “aureus” group, closely related to an undescribed species from north Ecuador. This finding increases the diversity of Thomasomys to 48 species, of which 18 species inhabit Ecuador. In addition, the species described herein is the largest species of the genus described in Ecuador.
Montane forest, Rodentia, Thomasomyini
The genus Thomasomys contains the highest diversity of any Sigmodontinae genus (
The subfamily Sigmodontinae is the most species rich subfamily of Cricetidae (
Currently, 47 species of Thomasomys are recognized (
We used Sherman traps with an accumulated trap effort of 5,675 trap/nights in very remote and difficult to access mountain regions of Sangay National Park, Ecuador (
We followed the main concepts explained by
We extracted DNA from tissues (liver and dry skin) of four specimens identified as Thomasomys aureus (MEPN 6144,
The sequences were edited in Geneious R11.5 (https://www.geneious.com) and aligned with CLUSTALW (
The IB and ML analysis presented different topologies within the aureus group. The IB analysis failed to recover the monophyly of the aureus group because the sample DQ914653 (Thomasomys sp, Bolivia) was located outside the aureus group (Fig.
Phylogenetic tree of the species of the group aureus, of the genus Thomasomys, based on the mitochondrial gene cytochrome b (cyt b). A Phylogenetic tree of Bayesian inference, the numbers represent the posterior probability values, PP>0.90 are considered high supports. B Phylogenetic tree of maximum likelihood, the numbers represent the bootstraps values, BS>70 are considered high supports.
Extension of the clade aureus of the phylogenetic tree of the aureus group. A Bayesian inference phylogenetic tree, numbers represent posterior probability values, PP>0.90 are considered high supports. B Maximum likelihood phylogenetic tree, numbers represent bootstraps values, BS>70 are considered high supports.
Genetic distance in percentage (K-2P) between the described species of the Thomasomys aureus group. The values on the right represent the standard deviation.
Taxa | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
1 T. apeco | 1.04 | 1.12 | 1.13 | 1.19 | 1.05 | 1.03 | 1.00 | 1.30 | 1.18 | 1.58 | 1.57 | |
2 T. sp. 1 PE Cusco | 10.88 | 1.00 | 0.99 | 1.11 | 1.12 | 0.96 | 1.06 | 1.14 | 1.12 | 1.55 | 1.50 | |
3 T. praetor | 11.42 | 10.99 | 0.93 | 0.97 | 1.05 | 1.06 | 1.02 | 1.09 | 1.09 | 1.50 | 1.19 | |
4 T. antoniobracki | 10.96 | 11.09 | 8.55 | 0.99 | 1.04 | 1.02 | 0.96 | 0.85 | 1.06 | 1.48 | 1.33 | |
5 T. aureus | 12.06 | 12.24 | 10.17 | 10.17 | 1.14 | 0.86 | 0.89 | 1.38 | 0.85 | 1.27 | 1.14 | |
6 T. pyrrhonotus | 11.53 | 12.54 | 10.37 | 9.65 | 9.91 | 1.02 | 1.00 | 1.34 | 1.09 | 1.45 | 1.52 | |
7 T. burneoi sp. nov | 10.72 | 12.48 | 10.41 | 8.88 | 4.69 | 9.47 | 0.44 | 1.10 | 0.72 | 1.06 | 1.04 | |
8 T. sp. Pichincha | 10.93 | 11.61 | 10.07 | 8.66 | 5.76 | 9.45 | 2.15 | 1.13 | 0.73 | 1.02 | 1.17 | |
9 T. auricularis | 11.17 | 11.64 | 8.42 | 5.86 | 9.74 | 8.15 | 10.07 | 8.78 | 0.81 | 1.74 | 1.43 | |
10 T. pardignasi | 12.49 | 12.65 | 10.50 | 9.06 | 4.73 | 10.00 | 5.26 | 5.51 | 7.48 | 1.14 | 1.06 | |
11 T. sp. El Angel | 13.34 | 12.60 | 10.53 | 11.41 | 7.42 | 10.77 | 4.05 | 4.67 | 5.45 | 6.30 | 1.26 | |
12 T. sp. Cajanuma | 12.33 | 12.02 | 10.20 | 10.61 | 6.59 | 11.23 | 4.75 | 5.87 | 6.85 | 5.29 | 7.09 |
The data presented in detail below suggest that the taxon discussed represents a new species. We provide below a description of the species, a comparison with other congeners and a discussion of their morphology and phylogenetic relationships. Relevant summaries of qualitative diagnostic traits variation are provided in Table
Tribe Thomasomyini Steadman & Ray, 1982
Genus Thomasomys Coues, 1884
Thomasomys praetor:
Thomasomys aureus:
Ecuador, Provincia de Morona Santiago, cantón Morona, parroquia Zúñac, Parque Nacional Sangay (Sangay National Park), Laguna Negra –2.179672° S, –78.502919° W (coordinates taken by GPS at the site of collection), elevation 3,553 m).
A species of Thomasomys from the aureus group described by the following character combinations: large size (combined head and body length 167–184 mm); postauricular patch present; wide metatarsal patch; hind foot large > 40 mm; M1 with broad and deep anteroflexus; additional anterior edge on procingulum of M1 present; M3 with metaflexus large and mesoloph distinctive; m1 with small and distinctive anterolophid; m1 with ectolophid; m2–m3 with hypoflexid wide; m3 size equals m2.
Head and body length = 172, Tail length = 232, Hind foot length = 43, Ear length = 27, Body mass = 105, Condylo-incisive length = 38.28, Zygomatic breadth = 22.04, Least interorbital breadth = 5.16, Length of rostrum = 13.14, Length of nasals = 14.53, Breadth of rostrum = 7.91, Orbital fossa length = 13.87, Length of upper diastema = 10.87, Crown length of maxillary toothrow = 7.8, Length of incisive foramina = 8.95, Breadth of incisive foramina = 3.13, Breadth of first maxillary molar = 2.84, Length of palatal bridge = 6.96, Breadth of bony palate = 3.34, Bullar breadth = 5.43, Depth of upper incisor = 2.05, Breadth of zygomatic plate = 3.98, Braincase breadth = 17.26, Length of mandible = 22.7, Crown length of mandibular toothrow = 8.2, Length of lower diastema = 5.17. External and craniodental of additional specimens are presented in Table
Large body size (head and body length combined with a range between 128 and 184 mm). Cinnamon-brown dorsal fur (Fig.
The cranium is large for the genus (38.2–40.13 mm of CIL). The rostrum is long, somewhat acuminate and narrow, with the nasal bones exceeding the anterior face of the incisors; poorly developed gnathic process (Fig.
Composed figure illustrating selected differences in the cranial anatomy of Thomasomys burneoi, sp. nov. (
Detail of the bulla in ventral view. A Thomasomys burneoi, sp. nov. (
Dentary moderately short, robust, with long and wide coronoid process that exceeds the upper edge of the condylar process, (Fig.
Opistodont incisors with orange front enamel; brachydont and pentalophodont molars (sensu
Tuberculum of first rib articulates with transverse processes of seventh cervical and first thoracic vertebrae; second and third thoracic vertebra with differentially elongated neural spine; thoracicolumbar vertebrae 19–20, the 16–17th with moderately developed anapophyses; sacrals 4; caudals 42, with complete hemal arches; 13 ribs present.
Thomasomys burneoi sp. nov., apart from being large (Fig.
Occlusal view of the right upper (A–C) and right lower (D–F) tooth row of: A, D Thomasomys burneoi sp. nov. (
Thomasomys burneoi sp. nov., differs from T. aureus (based on sensu stricto material,
Selected morphological differences with species that could be confused with Thomasomys burneoi sp. nov., compiled from
T. burneoi | T. pardignasi | T. aureus ss | T. auricularis |
Head and body length between 167–184 mm | Head and body length between 137–145 mm | Head and body length between 120–173 mm | Head and body length between 138–155 mm |
Tail ~ 119–136 % head-body length | Tail ~ 152 % head-body length | Tail ~ 125–141 % head-body length | Tail ~ 122–134 % head-body length |
Tail with 12-13 rows of scales per cm on the axis | Tail with 12 rows of scales per cm on the axis | Tail with 16 rows of scales per cm on the axis | Tail with 12 rows of scales per cm on the axis |
Genal 1 vibrissae present | Genal 1 and 2 vibrissae present | Genal 1 vibrissae present | Genal 1 vibrissae present |
Postauricular patch present | Postauricular patch absent | Postauricular patch absent | Ochraceous postauricular patch present |
Body mass > 100 gr. | Body mass < 100 gr. | Body mass < 100 gr. | Body mass < 100 gr. |
Upper maxillary row 7.72–8.30 mm | Upper maxillary row 6.4–6.6 mm | Upper maxillary row 6.90–7.42 mm | Upper maxillary row 6.6–7.4 mm |
Wide and robust presphenoid | Wide and robust presphenoid | Narrow presphenoid | Narrow presphenoid |
Auditory bullae small and inflated | Auditory bullae small and uninflated | Auditory bullae small and uninflated | Auditory bullae large and inflated |
Eustachian tube short and wide | Eustachian tube long and narrow | Eustachian tube long and wide | Eustachian tube short and narrow |
Moderately developed etmoturbinals | Undeveloped etmoturbinals | Moderately developed etmoturbinals | Moderately developed etmoturbinals |
Additional anterior edge on procingulum of M1 present | Additional anterior edge on procingulum of M1 absent | Additional anterior edge on procingulum of M1 absent | Additional anterior edge on procingulum of M1 present |
M1 with deep anteroflexus | M1 with shallow anteroflexus | M1 with deep anteroflexus | M1 with deep anteroflexus |
M1 with narrow anteroloph | M1 with wide anteroloph | M1 with wide anteroloph | M1 with wide anteroloph |
M1-M2 with narrow mesoloph | M1-M2 with wide mesoloph | M1-M2 with wide mesoloph | M1-M2 with wide mesoloph |
M3 with distintive mesoloph | M3 with indistinct mesoloph | M3 with indistinct mesoloph | M3 with indistinct mesoloph |
m1 with distintive anterolophid | m1 with indistinct anterolophid | m1 with indistinct anterolophid | m1 with distintive anterolophid |
Ectolophid present in m1 | Ectolophid present in m1 and m2 | Ectolophid absent | Ectolophid absent |
m1-m2 with ectostylid | m1-m2 lack ectostylid | m1-m2 with ectostylid | m1-m2 with ectostylid |
m2-m3 with wide hypoflexid | m2-m3 with narrow hypoflexid | m2-m3 with narrow hypoflexid | m2-m3 with narrow hypoflexid |
m3 equals m2 | m3 slightly shorter than m2 | m3 is longer than m2 | m3 equals m2 |
Weight (in grams) and measurements (in millimeters) of adult specimens of Thomasomys burneoi sp. nov. T. aureus. and T. pardignasi. Values of T. aureus and T. pardignasi were taken from
T. burneoi | T. pardignasi | T. aureus | |||||||||
Voucher |
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MEPN 6144 |
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Sex | M | F | M | F | F | F | F | F | M | ||
Age | 5 | 2 | 5 | 3 | 4 | 3 | 3 | 3 | 3 | ||
HB | 183 | 128 | 184 | 172 | 167 | 145 | 137 | 120 | 165.5 | ||
TL | 249 | [137] | 220 | 232 | 207 | 226 | 210 | 183 | 210.4 | ||
HF | 42 | 40 | 41 | 43 | 41 | 35 | 38 | 37 | 34 | ||
E | 25 | 24 | 28 | 27 | 25 | 23 | 21 | 24 | 23 | ||
W | - | - | 160 | 105 | 111 | 68 | 63 | 72 | - | ||
CIL | 40.8 | 32.49 | 40.13 | 38.28 | 39.18 | 33.1 | 32.21 | 32.72 | 36.57 | ||
ZB | 22.33 | 18.78 | 22.3 | 22.04 | 21.81 | 19.5 | 19.5 | 19.28 | 19.94 | ||
LIB | 4.78 | 5.12 | 5.47 | 5.16 | 5.13 | 5.1 | 5.33 | 5.17 | 5.12 | ||
LR | 14.52 | 11.07 | 13.98 | 13.14 | 13.53 | 11.54 | 11.31 | 11.26 | 12.63 | ||
LN | 17.41 | 13.22 | 16.74 | 14.53 | 15.01 | 13.47 | 12.27 | 12.52 | 15.26 | ||
BR | 5.88 | 5.04 | 8.4 | 7.91 | 7.71 | 5.81 | 6.24 | 6.2 | 6.43 | ||
OFL | 14.55 | 11.9 | 14.17 | 13.87 | 13.78 | 12.22 | 11.2 | 12.35 | 12.33 | ||
LD | 11.9 | 8.86 | 11.94 | 10.87 | 10.94 | 9.1 | 8.82 | 8.98 | 9.94 | ||
LM | 7.83 | 7.67 | 7.72 | 7.8 | 7.78 | 6.4 | 6.6 | 7.27 | 7.25 | ||
LIF | 9.68 | 7.48 | 9.29 | 8.95 | 8.64 | 6.6 | 6.51 | 7.04 | 8.43 | ||
BIF | 3.47 | 2.95 | 3.14 | 3.13 | 2.92 | 2.45 | 2.37 | 2.28 | 2.48 | ||
BM1 | 2.4 | 2.39 | 2.19 | 2.48 | 2.4 | 1.9 | 1.92 | 2.05 | 2.04 | ||
LPB | 6.88 | 6.26 | 7.32 | 6.96 | 6.88 | 6.12 | 6.09 | 6.61 | 6.84 | ||
BPB | 4.75 | 3.78 | 3.22 | 3.34 | 3.62 | 2.91 | 2.96 | 2.76 | 2.83 | ||
BB | 5.65 | 5.12 | 5.59 | 5.43 | 5.5 | 4.71 | 4.87 | 4.95 | 5.07 | ||
DI | 2.39 | 1.78 | 2.26 | 2.05 | 2.38 | 1.8 | 1.79 | 1.91 | 2.19 | ||
BZP | 4.03 | 3.15 | 4.08 | 3.98 | 3.49 | 3.27 | 3.25 | 3.43 | 3.73 | ||
BCB | 16.63 | 16.39 | 16.76 | 17.26 | 16.31 | 15.55 | 15.38 | 16.22 | 16.38 | ||
LMN | 23.45 | 18.83 | 23.44 | 22.7 | 22.8 | 19.1 | 19.03 | 19.74 | 20.84 | ||
LLM | 8.12 | 8.29 | 8.19 | 8.2 | 8.32 | 7.02 | 6.92 | 7.47 | 7.48 | ||
LLD | 5.64 | 4.79 | 5.19 | 5.17 | 5.03 | 4.14 | 4.09 | 4.58 | 4.4 |
Named for Santiago F. Burneo, of the Pontificia Universidad Católica del Ecuador, Quito, Ecuador in recognition of his teaching and support of mammalogists both in Ecuador and the United States of America. The specific epithet is a noun in the genitive case formed by the addition of an “i” to the stem of the name.
Known only from Sangay National Park, Chimborazo Province and Morona Santiago Province, Ecuador, 3,400–3,900 m in elevation (Fig.
Thomasomys burneoi sp. nov., has been recorded in the Altoandino floor (
The genus Thomasomys evolved into 48 recognized taxa, and most of these species are endemic to the Andes (
Based on molecular data T. burneoi falls into the T. aureus group (Fig.
The distribution of T. burneoi is poorly known, but we do know that it occurs in Sangay National Park; the elevation where these specimens were collected is around 3,400–3,900 m on the eastern slope of the Andes along the Cordillera Real or Oriental (Fig.
Recent expeditions to previously unexplored areas in Sangay National Park have resulted in the discovery of sanctuaries of diversity, from which numerous species new to science have been described (eg,
The authors declare no conflict of interest.
We thank the staff of the Ministry of Environment of Morona Santiago, especially Paúl Tito and Christian Clavijo, for their collaboration with logistic help in the field. Furthermore, we thank Glenda Pozo, Jenny Curay, Rocío Vargas, Érika Beltrán and Eulogio Zúñiga for their assistance during the work collecting specimens. Jorge Brito thanks Earth Deeds Carbon Mitigation Initiative of Pacific Lutheran University for the funds allocated to carry out part of the expeditions, and Diego Inclán, Francisco Prieto of INABIO for their sponsorship and permanent support. Tom Lee thanks the Clark Stevens endowment for funding work on this project. Mateo Vega kindly assisted in preparing Figure
Thomasomys sp. Pichincha (n=22). Pichincha, Lloa, Atacazo:
Thomasomys aureus (n=6). Azuay, Molleturo:
We included 30 sequences from different species of Thomasomys from the “aureus” group and some species from other groups of Thomasomys:
Accession Number | Identification |
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AF108679 | Chilomys intans |
KY366342 | Rhipidomys albujai |
KY366344 | Rhipidomys albujai |
HM594636 | Rhipidomys emiliae |
HM594628 | Rhipidomys ipukensis |
HM594659 | Rhipidomys leucodactylus |
HM594646 | Rhipidomys macrurus |
HM594643 | Rhipidomys mastacalis |
HQ634184 | Rhipidomys wetzeli |
MN557094 | Thomasomys paramorum |
MN557095 | Thomasomys paramorum |
MN557096 | Thomasomys paramorum |
MN557097 | Thomasomys paramorum |
MN557098 | Thomasomys paramorum |
DQ914643 | Thomasomys andersoni |
DQ914644 | Thomasomys andersoni |
MW788413 | Thomasomys antoniobracki |
MW788412 | Thomasomys antoniobracki |
MW788416 | Thomasomys apeco |
MW788414 | Thomasomys apeco |
MW788415 | Thomasomys apeco |
MW788418 | Thomasomys aureus |
MW788417 | Thomasomys aureus |
MN557061 | Thomasomys auricularis |
MN557124 | Thomasomys auricularis |
MN557125 | Thomasomys auricularis |
DQ914645 | Thomasomys australis |
DQ914650 | Thomasomys australis |
KR818876 | Thomasomys baeops |
KR818877 | Thomasomys baeops |
KR818878 | Thomasomys baeops |
MN557062 | Thomasomys bombycinus |
KR818905 | Thomasomys burneoi sp. nov |
MN557075 | Thomasomys burneoi sp. nov |
MN557077 | Thomasomys burneoi sp. nov |
DQ914648 | Thomasomys caudivarius |
MN557059 | Thomasomys caudivarius |
MN557060 | Thomasomys caudivarius |
MN557126 | Thomasomys caudivarius |
KR818895 | Thomasomys cinnameus |
KR818896 | Thomasomys cinnameus |
KR818897 | Thomasomys cinnameus |
AF108673 | Thomasomys daphne |
DQ914649 | Thomasomys daphne |
KY754167 | Thomasomys daphne |
EU579476 | Thomasomys erro |
KR818901 | Thomasomys fumeus |
AF108674 | Thomasomys gracilis |
MN557076 | Thomasomys hudsoni |
MN557078 | Thomasomys hudsoni |
MN557079 | Thomasomys hudsoni |
AF108675 | Thomasomys ischyurus |
AF108678 | Thomasomys kalinowskii |
DQ914647 | Thomasomys ladewi |
DQ914652 | Thomasomys ladewi |
AF108676 | Thomasomys notatus |
AF108677 | Thomasomys oreas |
MN557083 | Thomasomys pardignasi |
MN557084 | Thomasomys pardignasi |
MN557085 | Thomasomys pardignasi |
MW788421 | Thomasomys praetor |
MW788419 | Thomasomys praetor |
MW788420 | Thomasomys praetor |
MW788424 | Thomasomys pyrrhonotus |
MW788423 | Thomasomys pyrrhonotus |
MW788422 | Thomasomys pyrrhonotus |
KR818888 | Thomasomys salazari |
KR818889 | Thomasomys salazari |
KR818890 | Thomasomys salazari |
KR818900 | Thomasomys silvestris |
MN557063 | Thomasomys silvestris |
MN557064 | Thomasomys silvestris |
MW788426 |
Thomasomys sp. 1 sensu |
MW788425 |
Thomasomys sp. 1 sensu |
DQ914653 |
Thomasomys sp. 1 sensu |
MN557127 | Thomasomys sp. Cajanuma |
MN557089 | Thomasomys sp. El Angel |
MN557090 | Thomasomys sp. El Angel |
KR818879 | Thomasomys taczanowskii |
KR818880 | Thomasomys taczanowskii |
KR818881 | Thomasomys taczanowskii |
KR818882 | Thomasomys taczanowskii |
KR818883 | Thomasomys taczanowskii |
KR818884 | Thomasomys taczanowskii |
KR818885 | Thomasomys taczanowskii |
KR818886 | Thomasomys taczanowskii |
KR818887 | Thomasomys taczanowskii |
MN557069 | Thomasomys taczanowskii |
MN557070 | Thomasomys taczanowskii |
MN557071 | Thomasomys taczanowskii |
MN557086 | Thomasomys taczanowskii |
KR818898 | Thomasomys ucucha |
KR818899 | Thomasomys ucucha |
MN557093 | Thomasomys ucucha |
KR818902 | Thomasomys vulcani |
KR818903 | Thomasomys vulcani |
KR818904 | Thomasomys vulcani |