Saxatilomys paulinae Musser, Smith, Robinson & Lunde, 2005

Nguyen, Nghia Xuan, Nguyen, Dang Xuan, Ngo, Tuong Xuan & Nguyen, Duy Dinh, 2015, New data on recently described rodent species Paulina's Limestone Rat Saxatilomyspaulinae Musser, Smith, Robinson & Lunde, 2005 (Mammalia: Rodentia), Biodiversity Data Journal 3, pp. 4961-4961 : 4961

Saxatilomys paulinae Musser, Smith, Robinson & Lunde, 2005

Materials

Type status: Other material. Occurrence: recordedBy: Nghia Xuan Nguyen; individualCount: 1; sex: female; Location: country: Vietnam; stateProvince: Quang Binh; verbatimLocality: Thuong Hoa Commune, Minh Hoa District; verbatimElevation: 295 m; verbatimLatitude: 17°48'N; verbatimLongitude: 105°55'E; Event: eventDate: April 13, 2014; habitat: Karst forest; Record Level: collectionID: NXN-215; institutionCode: IEBR; collectionCode: DVZ-Rodentia; ownerInstitutionCode: IEBR

Type status: Other material. Occurrence: recordedBy: Nghia Xuan Nguyen; individualCount: 1; sex: male (juv.); Location: country: Vietnam; stateProvince: Quang Binh; verbatimLocality: Thuong Hoa Commune, Minh Hoa District; verbatimElevation: 315 m; verbatimLatitude: 17°48'N; verbatimLongitude: 105°55'E; Event: eventDate: April 14, 2014; habitat: Karst forest; Record Level: collectionID: NXN-217; institutionCode: IEBR; collectionCode: DVZ-Rodentia; ownerInstitutionCode: IEBR

Type status: Other material. Occurrence: recordedBy: Nghia Xuan Nguyen; individualCount: 1; sex: female; Location: country: Vietnam; stateProvince: Quang Binh; verbatimLocality: Thuong Hoa Commune, Minh Hoa District; verbatimElevation: 315 m; verbatimLatitude: 17°48'N; verbatimLongitude: 105°55'E; Event: eventDate: April 15, 2014; habitat: Karst forest; Record Level: collectionID: NXN-218; institutionCode: IEBR; collectionCode: DVZ-Rodentia; ownerInstitutionCode: IEBR

Type status: Other material. Occurrence: recordedBy: Nghia Xuan Nguyen; individualCount: 1; sex: male; Location: country: Vietnam; stateProvince: Quang Binh; verbatimLocality: Thuong Hoa Commune, Minh Hoa District; verbatimElevation: 298 m; verbatimLatitude: 17°48'N; verbatimLongitude: 105°55'E; Event: eventDate: April 17, 2014; habitat: Karst forest; Record Level: collectionID: NXN-221; institutionCode: IEBR; collectionCode: DVZ-Rodentia; ownerInstitutionCode: IEBR

Description

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 Table 1. The external and craniodental characteristics of all specimens fit well the diagnosis of Saxatilomys paulinae described in Musser et al. (2005). The rats have medium size (HB: 160.3 ± 2.03 mm, T: 192.3 ± 6.69 mm) with the following key specific characteristics: semispinous dark gray upperparts, dark frosted gray underparts, no sharp demarcation between dorsal and ventral fur and no white patches on the body (Fig. 1 and Fig. 2). Each palmar surface is covered with five huge and swollen pads while each plantar surface is covered with 6 very large and extremely bulbous pads (Fig. 3). Tail is slim, round in cross-section, gray in dorsal and lateral surfaces, whitish (un-pigmented) in ventral surface. The tail length is significantly longer than head-body length (adult: 113-129%, juvenile: 149%). Skull is elongated with narrow rostrum and wide braincase.

Distribution

The specimens of Saxatilomys paulinae were captured only in Thung Uc locality (17°48' N, 105°55' E) of Thuong Hoa Commune (Fig. 4). Local villagers reported they have captured this species in several localities near 3 villages of Thuong Hoa Commune (Ban On, Yen Hop and Mo-O villages). However, this information have not yet been verified by our trapping survey.

Ecology

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 (Fig. 5). This habitat type covers larger area in Thuong Hoa Commune where the species occurence was reported by local residents.

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 ( Nguyen et al. 2013).

Conservation

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.