A New Species of Ryukyu Spiny Rat, Tokudaia (Muridae: Rodentia), from Tokunoshima Island, Kagoshima Prefecture, Japan

Mammal Study 31: 47–57 (2006) © the Mammalogical Society of Japan

A new species of Ryukyu spiny rat, Tokudaia (Muridae: Rodentia), from Tokunoshima Island, Kagoshima Prefecture, Japan

Hideki Endo1,* and Kimiyuki Tsuchiya2,** 1 Section of Morphology, Primate Research Institute, Kyoto University, Inuyama, Aichi 484-8506, Japan 2 Laboratory of Wild Animals, Department of Animal Sciences, Faculty of Agriculture, Tokyo University of Agriculture, Atsugi, Kanagawa 243-0034, Japan

Abstract. A new species of Ryukyu spiny rat, Tokudaia tokunoshimensis was described in the specimens originating from Tokunoshima Island in the southernmost region of Japan. The populations of Tokudaia are separately distributed only in Amami-Oshima, Tokunoshima, and Okinawa-jima Islands. We have described the osteological and external morphological characteristics and clarified the osteometrical distinctions among the three populations using the skull and skin collections. All external dimensions of head and body length, tail length, hindfoot length and ear length were larger in the Tokunoshima population than in the other two in mean value. The raw osteometrical data separated the Tokunoshima Island population from the other two in all measurements except for the length of molar row in the Okinawa-jima Island population. The principal component analysis also demonstrated that the skulls from the Tokunoshima Island population were morphologically distinct from those of the other populations. Here, from these findings, we point out that the Tokunoshima population of Tokudaia should be regarded as an independent species from the two other populations.

Key words: osteology, Ryukyu spiny rat, Tokudaia muenninki, Tokudaia osimensis, Tokunoshima.

The Ryukyu spiny rats (genus Tokudaia) are distributed mal DNA (Tsuchiya et al. 1989), the mitochondrial DNA only in the three Islands of Amami-Oshima, Tokuno- sequence data also suggested that the population in shima and Okinawa-jima in the Ryukyu Islands of Japan. Tokunoshima Island were taxonomically separated from The first taxonomical record of the Ryukyu spiny rat was the population in Amami-Oshima Island (Suzuki et al. from the population in Amami-Oshima (Abe 1933), and 1999). All the other genetic data including blood serum the new genus Tokudaia was described for the popula- polymorphisms have consistently indicated the differen- tions (Kuroda 1943). Since the body size is larger in the tiations at a species level of the genus Tokudaia among Okinawa-jima Island population than in the Amami- the three populations. Oshima Island one, the population of Ryukyu spiny rat The detailed osteometrical comparisons (Kaneko from Okinawa-jima Island had been considered as a sub- 2001) demonstrated that the skulls of the Okinawa-jima species of Ryukyu spiny rat from Amami-Oshima Island population had a longer row of upper teeth from the inci- (Johnson 1964), and after that it had been generally sor to the third molar and possessed a wider first upper named as T. osimensis muenninki as shown in the species molar than those of the Amami-Oshima population, lists of the Asian mammals (Ellerman and Morrison- while the palatine foramen was situated more posteriorly Scott 1951; Corbet and Hill 1992). in the skulls of the Okinawa-jima population than those The variations of karyotype were obviously revealed of the Amami-Oshima population. These skull charac- among the three island populations of Tokudaia (Honda teristics supported the theory that the two populations et al. 1977, 1978; Tsuchiya 1979, 1981; Tsuchiya et al. should belong to the valid species T. muenninki and T. 1989). In addition to the restriction fragments length osimensis, respectively, unlike the original work on the polymorphisms of the mitochondrial DNA and riboso- Okinawa-jima population (Johnson 1964). However, no

*To whom correspondence should be addressed. E-mail: [email protected] **Present address: Ooyo-Seibutsu Co. Ltd., 4-12-3 Minami- Aoyama, Minato-ku, Tokyo 107-0062, Japan 48 Mammal Study 31 (2006) morphological comparison using the Tokudaia speci- Table 1. Locality and sex composition of the skull specimens. mens from Tokunoshima Island has been carried out. Origin of Specimens Symbols Male Female Tokunoshima T 1 2 Materials and methods Amami-Oshima A 11 5 Okinawa-jima O 7 3 We examined 29 skulls of the Ryukyu spiny rats 19 10 (genus Tokudaia) that had been stored in the Department of Zoology, National Science Museum, Tokyo (Tokyo, Japan), and the Mammal Division, the National Museum Table 2. List of measurements and their abbreviations. of Natural History in the Smithsonian Institution (Wash- Cranium ington DC, U.S.A.) (Appendix 1). Sex determination Profile length PL was dependent on the biological data for each speci- Maximum length ML men. Only specimens of adults with fully erupted molars Basal length BL were examined. The composition of origin and sex, and Short lateral facial length SL locality symbols are shown in Table 1. The skulls were Length from Prosthion to Bregma LPB Oral zygomatic breadth OZB measured with vernier calipers to the nearest 0.05 mm Zygomatic breadth ZB based on the examples of lagomorphs, artiodactyls and Maximum width of the nasal bone MWN carnivores in the textbook by Driesch (1976) (Table 2, Least breadth between the orbits LBO Fig. 1). The external measurements from the original Greatest neurocranium breadth GNB data of the specimens are also arranged in Table 2. The Greatest breadth of the occiputal condyles GBO head and body length and tail length were measured to Median palatal length MPL the nearest 0.5 mm, the hindfoot and ear lengths, to the Dental length DL nearest 1 mm. In the skull measurements the statistical Length of molar row LMR1 differences in mean values among the three populations Greatest palatal breadth GPB were examined by Student’s t-test. The proportion Length from Basion to Staphylion LBS indices were the quotients of each measurement value Length from Basion to the most rostral point of LBR zygomatic arch divided by the geometric mean of all measurement Length from Basion to the most medial point of orbit LBM values. The significant differences in proportion indices Length from Basion to Bregma LBB were examined among localities by non-parametric U- Height from Akrokranion to Basion HAB test using software Statistica (Statsoft Inc., Tokyo, Japan). Mandible The principal component analysis was also carried out Length from the condyle LC with all skull measurement data to clarify the variations Length from the angular process LA among the three geographical localities. The 16 skin Length of molar row LMR2 specimens were examined to confirm the external char- Aboral height of the vertical ramus AHR acteristics of the Tokunoshima population (Appendix 1). External measurements Head and body length HBL Tail length TL Results Hindfoot length HFL Ear length EL Taxonomic description: The measurement items of the skull were based on Driesch (1976). Tokudaia tokunoshimensis sp. nov. [Japanese name: Tokunoshima Toge-nezumi, new] M33903, adult female. These were collected in the same locality, on 17 December 1988 and 2 March 1987, Holotype: NSMT-M33901, adult female, skin and respectively, also by Kimiyuki Tsuchiya. Both are skull collected in a forest of Mikyo Area of Amagi-cho stored in the National Science Museum, Tokyo. Town in Tokunoshima Island on 14 May 1987 by Type locality: Mikyo Area, Amagi-cho Town, Tokuno- Kimiyuki Tsuchiya. The holotype is preserved in the shima Island, Kagoshima Prefecture, Japan. National Science Museum, Tokyo. Diagnosis: A middle-sized rat which is dark-brown Paratype: NSMT-M33902, adult male and NSMT- above, light gray and buff beneath. The ventral side of Endo and Tsuchiya, New species of spiny rat from Tokunoshima 49

Fig. 1. Measurements used in this study. Abbreviations are also explained in Table 2.

Table 3. Skull and external dimensions (mm) in the holotype and paratype specimens.

PL ML CBL SL LPB OZB ZB MWN LBO GNB GBO MPL DL LMR1 NSMT-M33901 39.60 39.45 35.40 17.25 29.45 17.75 18.40 4.55 8.05 15.45 9.25 21.25 20.40 6.15 NSMT-M33902 39.20 39.25 35.95 17.10 29.55 18.25 18.80 4.70 8.05 15.85 9.25 20.90 19.90 5.95 NSMT-M33903 38.60 38.45 35.30 17.00 28.65 18.60 18.45 4.10 7.90 15.80 9.55 20.65 19.60 6.05

Position of GPB LBS LBR LBM LBB HAB LC LA LMR2 AHR HBL TL HFL EL palatine foramen* Left Right 7.60 14.45 25.45 22.50 14.90 9.50 21.85 19.85 6.50 6.85 141.0 – 38 35 m p 7.95 14.80 26.75 22.00 15.05 9.60 21.75 20.15 6.00 6.95 170.0 – 37 34 m p 7.80 14.65 26.45 22.90 15.50 9.55 21.65 19.95 6.20 6.85 153.5 117.5 38 33 m p *Position of the palatine foramen in comparison to the postrior end line of the anterostyle of the second molar: p, postrior; m, middle position. the head and throat regions is also grayish. The tail is not is not particularly elongated. The positions of the so long, blackish on the upper and whitish on the lower palatine foramen of the skulls are arranged in Table 3. side. Its tip seems black also on the ventral side. The The auditory bulla is rounded but flat dorso-ventrally. spine is dark-brown and black, but its base is light gray. The coronoid process is not dorsally extended in the The spine is hard, and reaches 15–25 mm in length, and mandible. The photographs of the specimens are shown it cannot be seen around the mouth, ear, and extremities. (Figs. 2–4). The data of external and skull dimensions of The ears are rounded and large. The skull is similar to the holotype and paratypes are shown in Table 3. The that of the genus Tokudaia from other localities, but values of the external measurements of the three popu- larger than any other population. The braincase is lations are arranged in Table 4. The raw measurement enlarged laterally and flat dorso-ventrally. The rostrum data, proportion indices, and the statistical differences 50 Mammal Study 31 (2006)

Fig. 2. Holotype cranium specimen (NSMT-M33901). A, dorsal aspect. B, Ventral aspect. C, Left lateral aspect. Fig. 3. Left lateral aspect of the holotype mandible specimen (NSMT-M33901). Fig. 4. Paratype skin specimen (NSMT-M33903). A, dorsal aspect. B, Ventral aspect.

among localities are shown in Tables 5–8. The results of arm of the X chromosome in the two XO-typed popula- the principal component analyses from the skull mea- tions of Tokudaia (Arakawa et al. 2002). surements are shown in the charts (Figs. 5–8, Table 9). In mammalian species, the absence of the Y chromo- some has been reported only in Tokudaia from the Discussion Amami-Oshima and Tokunoshima Islands (Tsuchiya et al. 1989; Sutou et al. 2001, Arakawa et al. 2002) and in The karyological studies were carried out in all island Ellobius lutescens (Just et al. 1995). And it suggests that populations of Tokudaia (Honda et al. 1977, 1978: the assumptive speciation may occur primarily between Tsuchiya 1979, 1981; Tsuchiya et al. 1989). The chro- Amami-Oshima-Tokunoshima group and Okinawa-jima mosome number was 2n = 45 for the Ryukyu spiny rat Island population based on the translocation of the Y from Tokunoshima Island, whereas it was 2n = 25 for T. chromosome onto the X chromosome. We also suggest osimensis osimensis from Amami-Oshima Island. These that the Amami-Oshima and Tokunoshima populations two populations had XO-type sex chromosomes in both were secondarily separated at a species level, since sexes. These studies also pointed out that the karyotype Robertsonian fusions had occurred only in the popula- was 2n = 44 indicating XY type sex-chromosome for T. tion isolated within Amami-Oshima Island as discussed osimensis muenninki from Okinawa-jima Island. Inter- by Sutou et al. (2001). estingly, Sry gene was not found in both populations The differentiation patterns of mitochondrial DNA from Amami-Oshima and Tokunoshima Islands with using several restriction enzymes demonstrated that the XO-typed sex chromosome; and the sex determination sequence divergence between the Tokunoshima and system does not depend on the Sry gene at least in these Amami-Oshima populations reached 16.2% (Tsuchiya et two populations (Sutou et al. 2001). It has also been al. 1989). The pattern of the restriction fragment length reported that the functional Y-linked genes such as Tspy polymorphism for spacer regions of nuclear ribosomal and Zfy were translocated onto the distal part of the long DNA genes suggest that the divergence time between the Endo and Tsuchiya, New species of spiny rat from Tokunoshima 51

Table 4. External measurement data in the three populations. The external dimensions point out that the measure- HBLTLFLEL ments of HBL, TL, FL and EL are larger in the Tokuno- shima population than in the two other populations at Tokunoshima Total 155.00 118.00 37.67 23.67 least in mean value (Table 4). The present osteometrical 14.53 0.58 0.58 data demonstrate that the skulls from Tokunoshima 3133Island population are morphologically distinguished Male* 154.00 118.00 38.00 23.00 from the two other populations of Tokudaia (Tables 5 1111and 6). Mean values are larger in Tokunoshima popula- Female 155.50 37.50 23.75 tion than in the two other populations in all measure- 20.51 0.71 0.35 ments except for LMR1 and LMR2 in T. muenninki 2022(Table 5). The statistical differences (P < 0.05) between Amami-Oshima Tokunoshima and the two other populations can be con- Total 141.69 109.93 33.75 22.69 firmed in many measurements in total and female speci- 13.94 13.17 1.18 1.08 mens (Table 6). In the case of the total specimens, only 16 15 16 16 MWN is not significantly different between Tokuno- Male 136.40 103.00 33.20 23.20 13.41 12.85 0.84 1.48 shima population and T. osimensis, whereas between the 11 10 11 11 Tokunoshima population and T. muenninki the differ- Female 144.09 113.40 34.00 22.45 ences are not significantly observed in the seven mea- 14.12 12.51 1.26 0.82 surements of OZB, MWN, GNB, MPL, DL, LMR1, and 5555LMR2. In the analysis of the male, only four measure- Okinawa-jima ments of OZB, ZB, MWN and LBO indicate no signifi- Total 148.44 105.78 35.20 22.86 cant difference between the Tokunoshima population 8.63 9.16 1.23 1.95 and T. osimensis; in fact, most measurements of the 99107Tokunoshima population are not significantly different Male 148.83 106.33 35.43 22.83 from those of the T. muenninki. As only one male skull 10.19 11.11 1.40 2.14 was available from the Tokunoshima population for this 6676 study, significant differences could not be easily con- Female 147.67 104.67 34.67 23.00 6.11 4.93 0.58 firmed. Since we suggest a tendency towards large sizes 3331in the male and female skulls of the Tokunoshima popu- lation, more skulls from the population should be exam- Mean values are arranged in upper, standard deviations in middle, and number of specimens in lower row. ined in the future. Although significant differences *Male from Tokunoshima Island consists of one specimen. cannot be discerned in the four measurements of OZB, GNB, HAB and LMR2 between the Tokunoshima popu- lation and T. muenninki, all measurement data obviously Tokunoshima and Amami-Oshima populations may be show the statistical differences between the Tokuno- 2–4 million years (Tsuchiya et al. 1989). From these shima population and T. osimensis in the analysis of studies, the taxonomic references suggest that the three the female. populations were genetically isolated and differentiated The proportion indices (Tables 7 and 8) reveal the sta- to a large extent (Musser and Carleton 1993; Nowak tistical differences in the six ratios of SL, OZB, GNB, 1999). Furthermore, the results from the sequence data HAB, LC and AHR between the Tokunoshima popula- of cytochrome b were consistent with the conclusions tion and T. osimensis, and in the seven ratios of LBO, indicating the genetic separation at an inter-specific level MPL, LMR1, LBS, LBR, KBM and LBR2 between the between the two populations from Tokunoshima and Tokunoshima population and T. muenninki in the analy- Amami-Oshima Islands (Suzuki et al. 1999). The data sis of total specimens. Since only one skull from the from 1140 nucleotide sequences revealed the divergence Tokunoshima population is available for the analysis of of 8.8% and the authors pointed out that the two popula- male, a non-parametric test could not be carried out to tions were genetically isolated for some million years, compare the skulls from Tokunoshima Island and the despite their having many chances to exchange genetic other two Islands. No ratios show statistical differences elements during the Pleistocene ice ages. related to females in the Tokunoshima populations. 52 Mammal Study 31 (2006) .047 0.438 0.000 0.011 0.000 0.008 .69 23.97 20.46 13.87 8.89 20.60 18.66 6.48 6.29 rmed between the two populations. ement of the three populations. 0.76 0.20 0.280.78 0.74 0.19 0.90 0.270.72 0.68 0.76 0.24 0.37 0.96 0.26 0.20 0.64 0.550.89 0.68 0.43 0.70 0.31 0.91 0.19 0.79 0.201.09 0.19 0.75 0.19 0.86 0.36 0.30 0.97 0.18 0.99 0.160.20 0.19 0.52 1.06 0.96 0.18 0.30 0.66 0.48 1.17 0.22 0.18 0.33 1.15 0.40 0.32 0.89 0.58 0.58 0.87 0.32 0.65 0.21 1.02 0.13 0.41 1.03 0.44 0.23 0.25 0.48 0.23 0.13 0.13 0.40 0.10 0.18 0.180.35 0.68 0.14 0.45 0.25 0.31 0.25 0.05 0.92 0.10 0.35 0.15 0.11 0.25 0.07 0.06 0.07 0.21 0.35 0.07 .000 0.000 0.049 0.399 0.004 0.006 0.020.001 0.230 0.000 0.000 0.070 0.001 0.414 0.000 0.044 0.000 0.012 0 .013 0.042 0.014 0.003 0.024 0.010 0.001 0.071 0.002 0.002 0.284 0.009 alues among the three populations. 0 0.0006 0.001 0.103 0.000 0.079 0.000 0.000 0.000 0.001 0.0007 0.002 0.000 0.029 0.0053 0.000 0.042 0.001 0.782 0.000 0.017 0.003 0.550 0.000 0.041 0.026 0.000 0.011 0.007 0.013 0.132 0.000 0.001 0.0571 0.093 0.001 0.015 0.002 0.1249 0.008 0.027 0.041 0.013 0.007 0.003 0.101 0.042 0.038 0.001 0.452 0.014 0.033 0.001 0.322 0.003 0.006 0.002 0.243 0.024 0.000 0.270 0.010 0.012 0.001 0.000 0.071 0.001 0.002 0.010 0.002 0.002 0.284 0.009 ficant differences are confi ficant differences deviations in each skull measur .26 7.20 14.92 8.30 18.47 17.52 5.60 7.00 12.78 23.05.26 19.65 7.33 13.48 15.44 8.90 8.38 19.01 20.63 17.53 19.26 5.70 6.29 5.74 7.17 12.87 23.96 20.70 13.90 8.89 20.77 18.76 6.52 6.23 rcentage in which the signi Siginificant differences of mean v 3 4.22 7.31 15.45 8.33 20.57 19.24 6.34 7.11 12 1 4.22 7.13 14.99 8.20 18.13 17.19 5.58 6.795 12.21 22.52 4.12 19.32 7.25 13.56 15.48 9.11 8.22 18.73 20.42 16.93 19.17 5.62 6.43 5.68 6.95 12.25 23.98 19.90 13.78 8.90 20.18 18.43 6.38 6.42 7 4.25 7.18 14.94 8.27 18.37 17.42 5.59 6.93 12.60 22.88 19.55 13.50 8.97 18.92 17.34 5.68 5.72 5 4.100 7.90 4.63 15.80 8.05 9.55 15.65 20.65 9.25 19.60 21.08 6.05 20.15 7.80 6.05 14.65 7.78 26.45 14.63 22.90 26.10 15.50 22.25 9.55 14.98 21.65 9.55 19.95 21.80 6.20 20.00 6.85 6.25 6.90 5 4.45 8.00 15.70 9.35 20.93 19.97 6.05 7.78 14.63 26.22 22.47 15.15 9.55 21.75 19.98 6.23 6.88 Table 6. Mean values (mm) and standard ons in lower row. Table 5. ach value indicates the limit pe standard deviati 1.17 1.14 1.450.85 0.72 0.71 0.92 1.03 0.80 0.37 0.71 0.59 0.18 0.941.83 0.33 0.72 1.58 0.36 0.20 1.730.44 0.20 0.28 0.79 0.03 0.62 0.16 1.24 0.13 0.13 1.18 0.13 0.61 0.88 0.25 0.23 0.71 0.39 0.28 0.63 0.08 0.35 0.13 0.89 0.47 0.13 0.24 1.54 1.38 1.45 0.66 1.02 1.03 0.73 0.20 0.33 0.56 0.30 0.74 1.06 1.04 1.36 0.64 0.83 0.86 0.73 0.18 0.31 0.31 0.18 0.62 0.28 0.14 0.39 0.11 0.07 0.35 0.28 0.11 0.00 0.28 0.00 0.25 0.50 0.53 0.35 0.13 0.49 0.43 0.22 0.31 0.09 0.22 0.17 0.30 PL ML CBL SL LPB OZB ZB MWN LBO GNB GBO MPL DL LMR1 GPB LBS LBR LBM LBB HAB LC LA LMR2 AHR PL ML CBL SL LPB OZB ZB MWN LBO GNB GBO MPL DL LMR1 GPB LBS LBR LBM LBB HAB LC LA LMR2 AHR Total 37.17 36.09 33.09 16.28 27.73 17.60 17.2 Male 34.90Female 34.98 31.25 34.64 14.90 34.40 25.89 30.39 17.09 14.59 17.13 25.48 16.48 4 16.6 Male 37.36Female 36.39 33.29 36.70 16.35 35.38 27.73 32.60 17.66 16.10 17.21 27.72 17.43 4 17.2 Total 34.82 34.80 30.98 14.81 25.76 16.90 16.9 Male* 38.60 38.45 35.30 17.00 28.65 18.60 18.4 Female 39.40 39.35 35.68 17.18 29.50 18.00 18.6 TXA 0.013 0.016 0.024 0.019 0.016 0.099 0.104 0.402 0.074 0.041 0.000 0.00 Total 39.13Total 39.05 35.55 17.12 29.22 18.20 18.5 TXA 0.000 0.000 0.000 0.000 0.000 0.011 0.001 0.066 0.000 0.000 0.000 0.00 TXOAXO 0.029 0.002 0.000 0.008 0.006 0.028 0.001TXO 0.018 0.000 0.176AXO 0.000 0.006 0.551 0.037 0.076 0.268 0.194 0.001 0.002 0.318 0.349 0.021 0.238 0.471 0.171 0.008 0.000TXO 0.514 0.003 0.001 0.21 0.487 0.250AXO 0.001 0.239 0.000 0.003 0.116 0.526 0 0.000 0.410 0.003 0.222 0.000 0.497 0.000 0.607 0.001 0.241 0.000 0.019 0.001 0.020 0.001 0.98 0.193 0.262 0.001 0.007 0.000 0.193 0.004 0 0.007 0.002 0.004 0.346 0.002 0.001 0.346 0.02 0.001 0.029 0 TXA 0.000 0.000 0.001 0.000 0.000 0.043 0.007 0.024 0.003 0.004 0.000 0.00 Okinawa-jima Amami-Oshima Male Tokunoshima Total Female Mean values are arranged in upper row, Island consists of one specimen. *Male from Tokunoshima Locality symbols are shown in Table 1. E Locality symbols are shown in Table Endo and Tsuchiya, New species of spiny rat from Tokunoshima 53 .025 0.021 0.018 0.035 0.011 0.016 2 0.999 0.630 1.4347 1.318 1.027 0.411 0.633 0.454 1.434 1.321 0.411 0.454 4 0.985 0.628 1.435 1.316 0.411 0.454 rmed between the two populations. urement of the three populations. 23 0.014 0.014 0.030 0.031 0.025 0 .011 0.011 0.014 0.028 0.046 0.042 0.011 0.029 0.020 0.019 0.008 0.010 .128 0.011.000 0.128 0.000 0.018 0.018 0.028 0.005.001 0.043 0.461 0.001 0.091 0.317 0.052 1.000 0.035 0.027 0.311 0.001 0.258 0.398 0.000 0.751 0.011 0.065 0.189 0.176 .025 0.000 0.013 0.053 0.040 0.002 0.180 0.258 0.053 0.000 0.655 0.221 0.297 0.053 0.025 0.053 0.053 0.053 0.025 .025 0.007 0.011 0.011 0.044 0.036 0.024 0.003 0.006 0.008 0.017 0.002 .027 0.010 0.015 0.014 0.056 0.027 0.004 0.003.022 0.008 0.010 0.010 0.015 0.024 0.030 0.003 0.031 0.021 0.024 0.018 0.020 0.037 0.008 0.016 .021 0.015 0.014 0.033 0.029 0.035 0.031 0.026 0.025 0.022 0.012 0.020 .025 0.014 0.014 0.032 0.020 0.028 0.037 0.027 0.026 0.025 0.014 0.021 ant ratios among the three populations. 0 1.317 0.399 0.513 0.965 1.729 1.48 4 0.094 0.057 0.823 0.074 0.146 0.146 0.911 0.019 0.0101 0.180 0.121 0.3713 0.245 0.010 0.248 0.439 0.083 0.053 0.248 0.439 0.083 0.439 0.248 0.121 0.083 0.053 0.248 0.121 0.564 0.053 0.564 0.699 0.248 0.053 0.083 1.000 8 1.298 0.401 0.517 0.970 1.752 1.51 7 1.326 0.398 0.512 0.9629 1.717 1.288 1.46 0.414 0.5130 0.932 1.289 1.693 0.412 1.446 0.515 0.999 0.940 0.664 1.696 1.400 1.447 1.282 0.992 0.420 0.656 0.423 1.399 1.289 0.420 0.422 6 1.2869 0.418 0.029 0.508 0.022 0.913 0.013 1.685 0.022 1.445 0.032 1.015 0.034 0.682 0.022 1.401 0.015 1.266 0.016 0.421 0.026 0.425 0.018 0.017 1 1.347 0.444 0.498 0.888 1.679 1.433 0.972 0.623 1.443 1.307 0.454 0.440 0 1.344 0.439 0.501 0.897 1.672 1.444 0.971 0.621 1.450 1.309 0.455 0.434 4 1.355 0.455 0.491 0.866 1.696 1.407 0.975 0.629 1.427 1.303 0.451 0.454 ficant differences are confi ficant differences andard deviations in each skull meas rcentage in which the signi Siginificant differences of measurem Proportion indices and st ons in lower row. Table 8. Table 7. ach value indicates the limit pe standard deviati PL ML CBL SL LPB OZB ZB MWN LBO GNB GBO MPL DL LMR1 GPB LBS LBR LBM LBB HAB LC LA LMR2 AHR PL ML CBL SL LPB OZB ZB MWN LBO GNB GBO MPL DL LMR1 GPB LBS LBR LBM LBB HAB LC LA LMR2 AHR 0.011 0.008 0.030 0.011 0.030 0.048 0.031 0.012 0.021 0.031 0.011 0.01 0.028 0.027 0.015 0.007 0.025 0.031 0.011 0.019 0.004 0.015 0.014 0.018 0 0.025 0.016 0.019 0.010 0.0000.033 0.020 0.024 0.015 0.041 0.006 0.0250.037 0.001 0.032 0.030 0.016 0.036 0.043 0.002 0.027 0.029 0.020 0.017 0.034 0 0.021 0.028 0.032 0.023 0.019 0.019 0.016 0.021 0.0 0.031 0.022 0.016 0 0.035 0.038 0.022 0.013 0.021 0.041 0.022 0.011 0.013 0.047 0.018 0.025 0 0.037 0.041 0.024 0.015 0.019 0.039 0.021 0.013 0.015 0.054 0.022 0.028 0 0.035 0.009 0.013 0.011 0.012 0.054 0.023 0.006 0.009 0.030 0.008 0.019 0 AXO 0.052TXA 0.063 0.258 0.004 1.000 0.033 0.245 0.160 0.053 0.001 0.053 0.077 0.245 0.042 0.121 0.298 0.699 0.077 0.121 0.000 0.699 0 0.053 0.245 0.12 Total 2.581Total 2.575 2.344 1.129 1.927 1.200 1.223 0.293 0.528 1.035 0.617 1.38 TXA 0.911 1.000 0.057 0.034 0.219 0.044 0.057 0.074 0.434 0.014 0.737 0.07 TXOAXO 0.398 0.091 0.045 0.063 0.004 0.176 0.082 0.128 0.000 0.176 0.002 0.237 0.225TXO 1.000 0.000 0.011 0.008AXO 0.028 0.008 0.564 0.043 0.171 0.083 0.018 0.456 0.003 0.083 0 0.025 0.000 0.248 0.180 0 0.083 0.025 0.083 0.025 1.000 0.655 0.083 0.297 0.083 0.025 0.083 0.101 0.083 0.297 0.08 0.025 0.025 0 Male* 2.557 2.547 2.338 1.126 1.898 1.232 1.222 0.272 0.523 1.046 0.633 1.36 Female 2.593 2.589 2.348 1.130 1.941 1.184 1.224Male 0.304 0.530 2.569 1.030 2.575 0.609 2.300 1.38 1.097 1.906 1.257 1.261 0.314 0.530 1.099 0.611 1.36 Total 2.576 2.575 2.291 1.095 1.906 1.249 1.255 0.315 0.531 1.106 0.612 1.35 Female 2.591 2.573 2.273 1.091 1.906 1.232 1.242 0.316 0.533 1.122 0.614 1.35 Total 2.604 2.529 2.318 1.140 1.943 1.232 1.207 0.296 0.512 1.083 0.584 1.44 Male 2.607 2.540 2.323 1.141 1.935 1.232 1.201 0.298 0.511 1.079 0.585 1.44 Female 2.595 2.502 2.305 1.138 1.960 1.233 1.220 0.291 0.513 1.095 0.581 1.44 Male Female Tokunoshima Total Amami-Oshima Okinawa-jima Mean values are arranged in upper row, Island consists of one specimen. *Male from Tokunoshima Locality symbols are shown in Table 1. E Locality symbols are shown in Table 54 Mammal Study 31 (2006)

Fig. 5. Principal component chart of skulls of the Ryukyu spiny rats Fig. 7. Principal component chart. The raw measurement data in between the first and second transformed variables from 24 measure- the female specimens were used. Vertical axis, the second principal ments. The raw measurement data in the total specimens were used. component. The symbols plotted in the chart are shown in Table 1 Horizontal axis, the first principal component. Vertical axis, the second principal com- ponent.

Fig. 6. Principal component chart. The raw measurement data in Fig. 8. Principal component chart. The same analysis as Figure 5. the male specimens were used. Vertical axis, the second principal Horizontal axis, the second principal component. Vertical axis, the component. third principal component.

As suggested by Kaneko (2001), the differences smaller and the neurocranium is longer in the skulls from are significantly confirmed in many ratios between T. Tokunoshima Island than in those from the Okinawa- muenninki and T. osimensis. The present findings demon- jima Island without size factor. strate that SL MPL, DL, LMR1 and LMR2 are larger, As indicated by Kaneko (2001), the DL is obviously whereas ZB, LBS, LBR, LBM and LBB are smaller in larger in T. muenninki than in T. osimensis. The skulls T. muenninki than in the two other populations (Tables from Tokunoshima Island, however, are as large as T. 7 and 8). It is consistent with the results (Kaneko 2001, muenninki in the raw data of DL and the significant dif- 2005) suggesting that the splanchnocranium is larger ferences cannot be confirmed between the two popula- and the neurocranium smaller in T. muenninki than in tions at least in the total and male specimens (Tables 5 T. osimensis. In the Tokunoshima population, SL, MPL, and 6). The length of the upper and lower molar row and DL are intermediate in the mean of the indices, (LMR1 and LMR2) are also much larger in the Tokuno- however, LBS, LBR and LBM are the largest. It sug- shima population and T. muenninki than in T. osimensis. gests that the splanchnocranium may be rostro-caudally Except for LMR1 in female, no comparisons show sig- Endo and Tsuchiya, New species of spiny rat from Tokunoshima 55 nificant differences in LMR1 and LMR2 between the Tokunoshima population and T. muenninki (Table 6). In

contrast, the proportion indices from the total specimens 50.709 70.698 41 0.760

generally show a statistical difference in LMR1 and 0.064 0.041

LMR2 between the Tokunoshima population and T. 3 0.165 0.180 muenninki (Tables 7 and 8). It suggests that the propor- tion related to the molar rows may be specific in the 0.043 –0.581 0.028 0.093 0.106 0.723 0.138 0.124 Tokunoshima population among Tokudaia populations. 0.643 0.672 0.437 0.362 1 0.080 0.636 0.027 0.098 The charts of the principal component analysis strongly suggest that the three populations are discontin- uously separated into the three groups (Figs. 5–7). The three populations are completely divided into each group in all analyses using the total, male and female speci- mens in the first and second principal components; 940 0.814 0.466 0.965 0.966 0.710956 0.89 0.782 0.485 0.958 0.964 0.755 0.87 923 0.919 0.507 0.983 0.977 0.629 0.9 however, only one plot is available for the male. It is noticeable that the plots of Tokunoshima are distinguish- able from those of T. muenninki in the second principal 81 –0.139 –0.124 –0.287 –0.591 0.16 component. Since the second principal component 49 –0.008 –0.140 –0.259 –0.619 0.089 represents the variations in skull shapes as shown in component analyses. character loading factors (Table 9), it suggests that the –0.608 –0.276 –0.135 –0.103 –0.621 –0.820 0.793 morphological differences between the Tokunoshima population and T. muenninki are not only due to the size, but also to the shape. In the second and third principal –0.016 –0.019 –0.055 0.077 –0.004 –0.075 –0.316 –0.476 0.067 0.082 0.018 – component chart, the plots of the three populations seem from the principal partially intermingled (Fig. 8). Since the chart elimi- 0.901 0.954 0.683 0.818 0.848 0.9460.890 0. 0.960 0.796 0.773 0.837 0.945 0. 0.914 0.938 0.476 0.899 0.888 0.950 0.

nated the size factor from the measurement data, the 3 –0.232 0.036 –0.620 0.078 0.829 0.577 0.478 –0.083 –0.286 0.109 0.557 –0.57 findings strongly support the morphological distinctions –0.325 0.345 0.298 0.840 –0.198 –0.3 –0.614 0.861 0.879 0.611 among the Tokunoshima population, T. muenninki and 9 –0.300 0.351 0.236 0.653 –0.273 –0.3

T. osimensis. 0.125 0.152 –0.367 –0.196 –0.538 0.259 0.390 0.213 0.111 0.371 0.674 –0.210 – In the skull specimens from Tokunoshima Island, we observe the type of the osteological characteristics in the position of the palatine foramen as shown in those of

T. muenninki (Kaneko 2001). The palatine foramina are Character loading factors observed discerned in a posterior and middle position on one side in the three skulls from Tokunoshima Island in compari- son with the line of the second molar anterostyle (Table Table 9. 3). We suggest that this characteristic may be partially dependent on the lengths of the splanchnocranium and molar row. The holotype and paratype skin specimens are similar in color to the description of the skins from the Amami- Oshima populations, while the color of the spine at the tip may be darker in T. muenninki than in T. osimensis n explained by each factor. (Kaneko 2005). Some measurements such as PL, BL, SL and OZB PL ML CBL SL LPB OZB ZB MWN LBO GNB GBO MPL DL LMR1 GPB LBS LBR LBM LBB HAB LC LA LMR2 AHR P.V.E.* (Table 2) are not commonly examined in the taxonomi- PC3 0.043 0.105 0.039 0.050 0.057 0.114 0.093 0.588 0.086 –0.477 0.061 0.031 PC2 –0.059 0.400 0.734 0.138 –0.219 0.511 0.496 –0.347 0.020 –0.670 –0.11 cal studies of the rodents. These items cannot be exactly measured in some specimens of the rodents. However, raw data PC2 0.141 –0.116 0.016 0.231 0.140raw data –0.062 –0.286 PC2 –0.388 –0.381 –0.208 0.18 0.017 –0.021 –0.229 –0.205 0.244 0.378 –0.205 0.313 – raw data PC2 0.065 –0.185 0.019 0.241 0.147 0.116 –0.138 –0.640 –0.365 0.291 proportin indices Total PC1 0.969 0.960 0.990 0.952 0.957 0.831 0.862 0.273 0.758 0.614 0.705 Male PC1 0.960 0.958 0.989 0.943 0.950 0.891 0.818 –0.025 0.701 0.606 0.588 Female PC1 0.988 0.971 0.995 0.966 0.968 0.767 0.930 0.675 0.855 0.670 0.875 our groups consistently used the items, since these mea- PC1Total 0.567 –0.389 0.597 0.870 0.572 –0.107 –0.526 –0.643 –0.602 –0.482 *Percentages of the variatio 56 Mammal Study 31 (2006) surements contribute to the functional and phylogenetic genes in two XO species of the Ryukyu spiny rat. Cytogenetic studies in many taxonomic groups including various and Genome Research 99: 303–309. Corbet, G. B. and Hill, J. E. 1992. The Mammals of Indomalayan squirrels (Endo et al. 1999, 2000, 2003, 2004a, b, c). As Region. British Museum Publications, Oxford University Press, the sizes are different between the Tokunoshima Island Oxford, 488 pp. populations and those in the other populations, we Driesch, A. 1976. A Guide to the Measurement of Animal Bones from Archaeological Sites. Harvard University Press, Cambridge. selected the measurements that contribute to future dis- Ellerman, J. R. and Morrison-Scott, T. C. S. 1951. Checklist of cussions on the adaptational strategy and phylogenetic Palaearctic and Indian Mammals, 1758 to 1946. British Museum status in each population of Tokudaia. We expect that (Natural History), London, 810 pp. the length and breadth of rostrum often used in the rodent Endo, H., Cuisin, J., Nadee, N., Nabhitabhata, J., Suyanto, A., Kawamoto, Y., Nishida, T. and Yamada, J. 1999. Geographical taxonomy actually are substituted for SL and MWN variation of the skull morphology of the common tree shrew respectively in our measurements. SL and MPL reflect (Tupaia glis). Journal of Veterinary Medical Science 61: 1027– the length of diastema, one of the traditional measure- 1031. Endo, H., Nishiumi, I., Hayashi, Y., Rerkamnuaychoke, W., ments in the osteometry of the rodents Kawamoto, Y., Hirai, H., Kimura, J., Suyanto, A., Nabhitabhata, The age ranks were advocated in an osteometrical J. and Yamada, J. 2000. Osteometrical skull character in the four study of the Ryukyu spiny rats (Kaneko 2001). In this species of tree shrew. Journal of Veterinary Medical Science 62: study, however, the detailed age determination was not 517–520. Endo, H., Kimura, J., Oshida, T., Stafford, B. J., Rerkamuaychoke, carried out, since the skulls with fully erupted molars W., Nishida, T., Sasaki, M., Hayashida, A. and Hayashi, Y. 2003. used in this study do not substantially cause a misunder- Geographical variation and its functional significances of skull standing in the present statistical comparisons. In addi- morphology in the red-cheeked squirrel. Journal of Veterinary Medical Science 65: 1179–1183. tion, as we will not be able to collect many specimens of Endo, H., Kimura, J., Oshida, T., Stafford, B. J., Rerkamuaychoke, endangered populations of the Ryukyu spiny rats, the W., Nishida, T., Sasaki, M., Hayashida, A. and Hayashi, Y. maximum sample size should be applied to the osteo- 2004a. Geographical and functional-morphological variations metrical analysis using the actual collections stored in of the skull in the gray-bellied squirrel. Journal of Veterinary Medical Science 66: 277–282. museums of the world. Endo, H., Kimura, J., Oshida, T., Stafford, B. J., Rerkamnuaychoke, Finally, all our morphological data in this study W., Nishida, T., Sasaki, M., Hayashida, A. and Hayashi, Y. strongly point out that the Tokudaia population in 2004b. Geographical variation of skull size and shape in various populations in the black giant squirrel. Journal of Veterinary Tokunoshima Island should be regarded as a new spe- Medical Science 66: 1213–1218. cies, T. tokunoshimensis, that is obviously distinct from Endo, H., Fukuta, K., Kimura, J., Sasaki, M. and Stafford, B. J. 2004c. the other two insular populations in this genus. Geographical variation of the skull in the lesser mouse deer (Tragulus javanicus). Journal of Veterinary Medical Science 66: 1229–1235. Acknowledgments: We thank Dr. Brian J. Stafford, Honda, T., Suzuki, H. and Itoh, M. 1977. An unusual sex chro- Dr. Richard W. Thorington, Jr., Dr. James Mead, Ms. mosome constitution found in the Amami spinous country-rat, Linda Gordon (Smithsonian Institution, Washington DC, Tokudaia osimensis osimensis. Japanese Journal of Genetics 53: 247–249. U.S.A), Dr. Shin-ichiro Kawada, Ms. Yoshimi Watanabe Honda, T., Suzuki, H., Itoh, M. and Hayashi, K. 1978. 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Wilson and D. A. Reeder, eds.) Mammal Species of the World: Tsuchiya, K. 1979. A contribution of the chromosome study in A Taxonomic and Geographic Reference, 2nd ed. Pp. 501–755. Japanese mammals. Proceedings of Japan Academy, Series B Smithsonian Institution Press, Washington DC. 55: 191–196. Nowak, R. M. 1999. Walker’s Mammals of the World, Vol. 2, 6th ed. Tsuchiya, K. 1981. On the chromosome variations in Japanese P. 1501. John Hopkins University Press, Baltimore and London. cricetid and murid rodents. Mammalian Science 42: 51–58 (in Sutou, S., Mitsui, Y. and Tsuchiya, K. 2001. Sex determination with- Japanese). out the Y chromosome in two Japanese rodents Tokudaia osimen- Tsuchiya, K., Wakana, S., Suzuki, H., Hattori, S. and Hayashi, Y. sis osimensis and Tokudaia osimensis spp. Mammalian Genome 1989. Taxonomic study of Tokudaia (Rodentia: Muridae): I. 12: 17–21. Genetic differentiation. Memoirs of National Science Museum, Suzuki, H., Iwasa, M. A., Ishii, N., Nagaoka, H. and Tsuchiya, K. Tokyo 22: 227–234 (in Japanese with English abstract). 1999. The genetic status of two insular populations of the endemic spiny rat Tokudaia osimensis (Rodentia, Muridae) of the Received 31 January 2006. Accepted 6 April 2006. Ryukyu Islands, Japan. Mammal Study 24: 43–50.

Appendix 1.

Specimen No. used in this study.

Tokunoshima Island male NSMT-M33903* female NSMT-M33901* NSMT-M33902* Amami-Oshima Island male NSMT-M7696* NSMT-M7699 NSMT-M7705* NSMT-M7712* NSM-M7715* NSMT-M11632* NSMT-M28668* NSMT-M28669* NSMT-M28670* NSMT-M33904* NSMT-M33906* female NSMT-M7695 NSMT-M7710 NSMT-M7714 NSMT-M7716 NSMT-M33905* Okinawa-jima Island male NSMT-M8422* NSMT-M14377* USNM278755 USNM278756 USNM278758 USNM278759 USNM278760 female USNM278761 USNM278762 USNM278763

NSMT-M means the specimen of National Science Museum, Tokyo, USNM indicates the specimens of the Smithsonian Institution. *The skin specimens could be also examined.