Biodiversity Data Journal : Taxonomic paper
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Corresponding author: Dang Xuan Nguyen ([email protected])
Academic editor: Riccardo Castiglia
Received: 24 Mar 2015 | Accepted: 15 May 2015 | Published: 19 May 2015
© 2015 Nghia Xuan Nguyen, Dang Xuan Nguyen, Tuong Xuan Ngo, Duy Dinh Nguyen.
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: Nguyen N, Nguyen D, Ngo T, Nguyen D (2015) New data on recently described rodent species Paulina's Limestone Rat Saxatilomys paulinae Musser, Smith, Robinson & Lunde, 2005 (Mammalia: Rodentia). Biodiversity Data Journal 3: e4961. doi: 10.3897/BDJ.3.e4961
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Paulina's Limestone Rat Saxatilomys paulinae Musser et al., 2005 was first discovered by
In April 2014, we conducted a rodent survey and collected four (4) whole specimens of Saxatilomys paulinae in Quang Binh province. This is the first record of Saxatilomys paulinae in Vietnam. External and craniodental characteristics of all specimens clearly exhibit the characters of Saxatilomys paulinae as described in
Rodent, morphology, Quang Binh, Khammouane, karst limestone forests, Central Indochina Limestone
The Central Indochina Limestone is the most extensive tracts of limestone karst habitat in Indochina (
Quang Binh limestone habitat is characterized by very specific natural conditions of precipitous karst ridges, which rise to elevations of around 400 m. Scattered among this ridges are narrow valleys and pockets of igneous rock formations. The limestone karst is almost entirely forested, apart from steep cliff faces. The forest clearance occurs only in flat valleys within the limestone massif and in lowland area bordering it. The most widespread forest type in the landscape is limestone evergreen forest, but there are also significant areas of lowland evergreen forest distributed on non-calcareous substrate in valleys among the limestone karsts (
We used Sherman live traps and Tomahawk live traps to sample the rodent specimens. At each survey location, trap-transects were established within various habitat types and contain 30-50 traps each depending on habitat type. Traps were set at each transect for 4–6 days and checked on subsequent mornings (for specimens and for bait replacement). Baits were made of fresh manioc or sweet potato. All captured animals were anesthetized and measured for external measurements following
Those individuals that could not be identified to the species level in the field (this includes all specimens of Saxatilomys paulinae) were preserved in 70% ethanol for later identification using museum mammal collections. Species identification follows
Study of habitat was carried out using transect and plot techniques (
Four whole specimens of Saxatilomys paulinae (two adult females, one adult male and one juvenile male) were collected in April 2014. The external and craniodental measurements of these specimens are shown in
External and crania-dental measurements of Saxatilomys paulinae specimens from Vietnam and those of specimens from Laos.
Note: * statistics of 3 adult specimens (NXN-215, NXN-218 and NXN-221) collected in Phong Nha - Ke Bang NP; ** data from specimens collected in Phoun Hin Poun NBCA, Lao PDR (in
Measu rement |
Specimens from Vietnam |
Statistics of specimens from Vietnam* |
Statistics of specimens from Lao** |
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NXN-217 |
NXN-221 |
NXN-218 |
NXN-215 |
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Sex |
♂ (juv.) |
♂ (adult) |
♀ (adult) |
♀ (adult) |
♂ & ♀ |
♂ & ♀ |
HB |
116 |
157 |
160 |
164 |
160.33 ± 2.03 (157-164) 3 |
(144-150) 2 |
T |
164 |
203 |
180 |
194 |
192.33 ± 6.69 (180-203) 3 |
(167-168) 2 |
T/HB (%) |
141 |
129 |
113 |
118 |
(113-129) 3 |
(112-116) 2 |
HF |
28.42 |
29.68 |
29.25 |
30 |
29.64 ± 0.22 (29.25-30.0) |
32-32 |
E |
23.52 |
24.96 |
25.18 |
25.42 |
25.19 ± 0.13 (24.96-25.42) 3 |
(24-25) 2 |
W |
50 |
130 |
110 |
110 |
116.67 ± 6.67 (110-130) 3 |
|
ONL |
36.54 |
43.69 |
42.71 |
42.81 |
43.07 ± 0.31 (42.71-43.69) 3 |
36.0 ± 1.37 (33.3-40.5) 48 |
ZB |
16.8 |
19.3 |
19.03 |
18.79 |
19.04 ± 0.15 (18.79-19.3) 3 |
16.9 ± 0.62 (15.7-18.9) 48 |
IB |
6.0 |
6.18 |
6.43 |
6.39 |
6.33 ± 0.08 (6.18-6.43) 3 |
5.8 ± 0.29 (5.1-6.5) 48 |
LR |
11.34 |
14.2 |
13.57 |
13.97 |
13.91 ± 0.18 (13.57-14.2) 3 |
11.0 ± 0.65 (9.7-12.7) 48 |
BR |
5.26 |
6.74 |
6.63 |
6.62 |
6.66 ± 0.04 (6.62-6.74) 3 |
5.9 ± 0.31 (5.3-6.7) 48 |
BBC |
15.87 |
16.27 |
16.53 |
16.02 |
16.27 ± 0.15 (16.02-16.53) 3 |
15.0 ± 0.36 (14.3-16.2) 48 |
HBC |
15.87 |
16.27 |
16.53 |
16.02 |
16.27 ± 0.15 (16.02-16.53) 3 |
9.9 ± 0.36 (9.0-10.9) 48 |
BZP |
3.5 |
4.77 |
4.41 |
4.52 |
4.57 ± 0.11 (4.41-4.77) 3 |
3.4 ± 0.26 (2.9-4.0) 48 |
LD |
8.19 |
11.69 |
11 |
10.63 |
11.11 ± 0.31 (10.63-11.69) 3 |
9.1 ± 0.54 (7.9-10.4) 48 |
LIF |
6.36 |
7.61 |
6.42 |
7.1 |
7.04 ± 0.34 (6.42-7.61) 3 |
6.6 ± 0.45 (5.6-7.5) 48 |
BIF |
2.24 |
2.49 |
2.43 |
2.33 |
2.42 ± 0.05 (2.33-2.49) 3 |
2.6 ± 0.19 (2.2-3.1) 48 |
LBP |
8 |
9.47 |
9.84 |
9.54 |
9.62 ± 0.11 (9.47-9.84) |
6.1 ± 0.36 (5.3-6.9) 48 |
BBP |
3.06 |
3.69 |
3.89 |
3.45 |
3.68 ± 0.13 (3.45-3.89) 3 |
3.3 ± 0.19 (3.0-3.9) 48 |
PPL |
10.74 |
13.72 |
12.61 |
12.81 |
13.05 ± 0.34 (12.61-13.72) 3 |
12.3 ± 0.68 (10.9-14.5) 48 |
BMF |
2.5 |
2.83 |
2.46 |
2.43 |
2.57 ± 0.13 (2.43-2.83) 3 |
2.7 ± 0.24 (2.3-3.4) 48 |
LB |
5.38 |
5.79 |
5.32 |
5.57 |
5.56 ± 0.14 (5.32-5.79) 3 |
5.4 ± 0.18 (5.5-5.8) 48 |
CLM1-3 |
7.7 |
7.81 |
7.57 |
7.86 |
7.75 ± 0.09 (7.57-7.86) 3 |
6.2 ± 0.17 (5.8-6.5) 48 |
BM1 |
2.08 |
2.03 |
1.95 |
1.97 |
1.98 ± 0.02 (1.95-2.03) 3 |
1.8 ± 0.08 (1.7-2.0) 48 |
Living specimen of Saxatilomys paulinae from Quang Binh province (the nose is wounded by trapping).
The specimens of Saxatilomys paulinae were captured only in Thung Uc locality (17°48' N, 105°55' E) of Thuong Hoa Commune (
All specimens of Saxatilomys paulinae were collected at the base of a Thung Uc karst tower (Thuong Hoa Commune), at elevation of 295 - 315 m, under limestone humid evergreen forest (
The habitat is characterized by complicated terrain comprising low karst towers (around 400 m) with steep slopes covered under limestone humid evergreen forest. The slopes have many large limestone boulders and crevices. The forest on the slopes has been affected by selected timber logging in the past; however, a 3-4 layer forest structure remains, with the following characters:
The canopy tree layer consists of trees 20-30 m high with stem diameter 0.5-0.8 m. The most common trees species are: Pometia pinnata (Sapindaceae), Dracontomelon duperreanum (Anacardiaceae), Toona surenii (Meliaceae), Paviesia anamensis (Sapindaceae), Pterospermum grewiaefolium (Sterculiaceae), Mahuca sp., Hopea sp., Streblus asper (Moraceae), Litsea sp. (Lauraceae), Sumbaviopsis macrophylla (Euphorbiaceae), Actinodaphne sp. (Lauraceae), Pometia chinensis (Sapindaceae), Choerospondias axillaris (Anacardiaceae), Alangium ridleyi (Alangiaceae), Knema sp. (Myristicaceae), etc.
The middle tree layer consists of trees 10-15 m high with stem diameter 0.3-0.5 m. The most common species are Knema corticosa (Myristicaceae), Streblus tonkinensis, Streblus asper (Moraceae), Xylopia vielana (Annonaceae), Diospyros sp. (Ebenaceae), Caryota mitis (Arecaceae), Arenga pinnata (Arecaceae), Camelia sp. (Theaceae), Actinodaphne sp. (Lauraceae), Pterospermum sp. (Sterculiaceae), Litsea sp. (Lauraceae), Ormosia laoensis (Fabaceae), Nephelium lappaceum (Sapindaceae), Sumbaviopsis macrophylla (Euphorbiaceae), Paranephelium spirei (Sapindaceae), Alangium ridleyi (Alangiaceae), Baccaurea sp. (Euphorbiaceae), Aglaia sp. (Meliaceae), etc.
The scrub layer consists of trees 3-7 m high, mostly with twisted stems, many branches, and several stems rising from one base. The most common species are from the families Euphorbiaceae, Theaceae, Myrtaceae and Verbenaceae. Some dominant species are Antidesma sp. (Euphorbiaceae), Trevesia panmalta (Araliaceae), Litsea valiabilis (Lauraceae), Arenga pinnata (Arecaceae), Excoecaria cochinchinensis (Euphorbiaceae), as well as seedlings of trees from higher layers.
The herb and fern layer is about 0.5-3 m high, with trees of 0.2-3 m high from family Araceae, the genera Calamus and Caryota (family Arecaceae), and many herb species from families Urticaceae, Melastomataceae, Balsaminaceae, Poaceae, Begoniaceae, Podipoliaceae, Convallariaceae, Zingiberaceae, Urticaceae and Acanthaceae. Some of the most common species are Homalomena occulta (Araceae), Aglaonema simplex (Araceae), Aglaonema siamensis (Araceae), Tacca chantrieri (Taccaceae), Aspidistra typica (Convallariaceae), Piper sp. (Piperaceae), Corymborkis veratrifolia (Orchidaceae), etc.
Apart from Saxatilomys paulinae, several other ground-living rodent species are found in this habitat including Bandicota indica, Berylmys bowersi, Leopoldamys sabanus, Leopoldamys edwardsi, Maxomys moi, Maxomys surifer, Niviventer fulvescens, Niviventer langbianis, Niviventer tenaster, Rattus tanezumi, Rattus andamanensis, and Laonastes aenigmamus (
Main threats to the population of Saxatilomys paulinae in Quang Binh province (Vietnam) is wildlife hunting and habitat disturbance. The distribution area of the Saxatilomys paulinae is situated close to the villages of ethnic minorities (Ruc, Sach, and Chut). These minority groups are very poor and their livelihood much depends on wildlife and forest products. Wildlife hunting is a long tradition of the local people, and a practice that remains extensive currently. Most men 15 to 60 years in age in these villages are engaged in wildlife hunting. Their hunting season lasts about eight months per year (from July to February). The most widely used mean for trapping rodents is metal spring snares. Each hunter usually keeps 30-100 active snares in forests; some hunters keep up to 300-500 active snares. Unfortunatlely, we were not able to estimate how many individuals of Saxatilomys paulinae they capture each year.
Simple comparison of external and craniodental measurement of specimens from Vietnam with those of specimens from Lao indicates that specimens from Vietnam are generally larger than specimens from Lao (
In Lao, Saxatilomys paulinae was reported to inhabit steep rocky slopes with large limestone boulders covered in heavily degraded deciduous forest mixed with scrub and bamboo at the base of the surrounding massive karst (
Before this study, Saxatilomys paulinae was recorded only in the Phoun Hin Poun NBCA in Khammuoane province of Lao (
It is interesting that both Saxatilomys paulinae and Laonastes aenigmamus share the same limestone forest habitat in Central Indochina Limestone. The Laonastes aenigmamus is the only surviving member of the otherwise extinct rodent family Diatomyidae, that was formerly believed to have been extinct for more than 11 million years (
This research is funded by Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grant number 106.15-2011.14