List of comparative skeletal specimens examined (including partially skeletonized specimens). Institutional and collection abbreviations are as follows: collection number of University Museum of the Kagoshima University, Kagoshima, Japan (OT, IK, HT); Kyoto University Museum Zoological collection, Kyoto University, Kyoto, Japan (KUZ); Yasuyuki Nakamura private collection (NPN); and National Science Museum Tokyo collection, Tokyo, Japan (NSMT).
Bombina orientalis: NPN 178, 179, Gangwong-do, South Korea (one male and one female).
Bufo bankorensis: NPN 105, Yilan Co., Taiwan; NPN 106-110, Wulai, Taipei Co., Taiwan (two males and four females).
Bufo gargarizans miyakonis: NPN 097, 098, four un-catalogued specimens, Miyakojima Is., Okinawa Pref., Japan (four males and two females).
Bufo japonicus formosus: NPN 065, 066, 068, 069, Kanagawa Pref., Japan (three males and one female).
Bufo japonicus japonicus: NPN 082-084, 089, 090, Kagoshima Pref., Japan (three males and two females).
Bufo torrenticola: NPN 070-072, 076, 077, Nara Pref., Japan (three males and two females).
Duttaphrynus melanostictus: NPN 100, 101, Keelung, Taiwan; NPN 099, Taoyuan Co., Taiwan; NPN 102, Ranong, Thailand (two males and two females).
Hyla japonica: KUZ R56877, Nagano Prf., Japan; NPN 664, 665, Oita Prf., Japan; NPN 1109, Shizuoka Prf., Japan (one male and three females).
Hyla hallowellii: NPN 308, 309, 311, 312, Okinawajima Is., Okinawa Prf., Japan (two males and two females).
Fejervarya kawamurai: NPN 030-034, 1127, 1128, 1134, 1135, Okinawajima Is., Okinawa Prf., Japan; KUZ R56879, R56880, Wakayama Prf., Japan (four males and seven females).
Fejervarya sakishimensis: NPN 114, 116, 117, Ishigakijima Is., Okinawa Prf., Japan (one male and two females).
Limnonectes fujianensis: NPN 325, 327, Taipei Co., Taiwan (one male and one female).
Limnonectes namiyei: KUZ R65738, R71534, R72180, R72422, R72423, Okinawajima Is., Okinawa Prf., Japan (two males and three females).
Babina holsti: KUZ R62704, R62978, R72031, NSMT 00855, Okinawajima Is., Okinawa Prf., Japan (three males and one female).
Babina subaspera: OT-880815-01, OT-940723-03, OT-940723-04, OT-940725-06, OT-940726-07, KUZ R28159, Amamioshima Is., Kagoshima Prf., Japan (two males and four females).
Glandirana emeljanovi: NPN 192, 193, Gangwong-do, South Korea (two females).
Glandirana rugosa: KUZ R56881, R 56882, R56884, Wakayama Prf., Japan; NPN 046, 047, 722-725, Oita Prf., Japan (four males and five females).
Hylarana guentheri: KUZ R38877, Matsu Is., Taiwan (one female).
Hylarana latouchii: NPN 160, 164, Taipei Co., Taiwan (one male and one female).
Lithobates catesbeianus: NPN 1012, Okinawajima Is., Okinawa Prf., Japan; NPN 1122, Iheyajima Is., Okinawa Prf., Japan (two males).
Nidirana adenopleura: NPN 155, 156, Taipei Co., Taiwan (one male and one female).
Nidirana (or Babina) okinavana : NPN 125, 126, 128, 131, Ishigakijima Is., Okinawa Prf., Japan (two males and two females).
Odorrana amamiensis: NPN 132, 133, 135, 136, 294, Amamioshima Is., Kagoshima Prf., Japan (three males and two females).
Odorrana ishikawae: KUZ R57893, R62749, R65737, Okinawajima Is., Okinawa Prf., Japan (two males and one female).
Odorrana splendida: KUZ R28147, R28155, R28156, R28159, Amamioshima Is., Kagoshima Prf., Japan (two males and two females).
Odorrana narina: NPN 003, 014-018, 269, 271, 276-278, 284, 372-376, Okinawajima Is., Okinawa Prf., Japan (nine males and eight females).
Odorrana supranarina: NPN 355-358, 360, 361, Ishigakijima Is., Okinawa Prf., Japan (three males and three females).
Odorrana utsunomiyaorum: KUZ R62289, Ishigakijima Is., Okinawa Prf., Japan; KUZ R62458, R62459, R62461, Iriomotejima Is., Okinawa Prf., Japan (two males and two females).
Pelophylax nigromaculatus: KUZ R56872, R56874, NPN 662, 663, Nagano Prf., Japan; NPN 667-670, Oita Prf., Japan; NPN 813, 814, Nara Prf., Japan (three males and seven females).
Pelophylax porosus porosus: NPN 211, 214, 216, 217, Nagano Prf., Japan (two males and two females).
Pelophylax porosus brevipodus: NPN 049-055, Nagano Prf., Japan; NPN 1114, 1116, Shiga Prf., Japan (three males and five females).
Rana dybowskii: NPN 245-247, 249, Tsushima Is., Nagasaki Prf., Japan (two males and two femals).
Rana huanrensis: NPN 170, Gangwong-do, South Korea (one male).
Rana japonica: NPN 330-332, 044, 045, 661, 666, Oita Prf., Japan (three males and four females).
Rana kobai: NPN 827, 828, Kakeromajima Is., Kagoshima Prf., Japan; NPN 1106-1108, 1111, Amamioshima Is., Kagoshima Prf., Japan (four males and two females).
Rana longicrus: KUHE 50594, Taipei Co., Taiwan (one female).
Rana ornativentris: KUZ R56888, R56889, Nagano Prf., Japan; NPN 321, 322, 324, Kanagawa Prf., Japan (two males and three females).
Rana pirica: NPN 316, 317, Hokkaido Prf., Japan (one male and one female).
Rana sakuraii: NPN 336-339, Kanagawa Prf., Japan (two males and two females).
Rana sauteri: KUHE 50596, Tainan, Taiwan (one female).
Rana tagoi tagoi: KUZ R56878, Hyogo Prf., Japan; NPN 021, 022, 048, 334, 335, 342-344, Kanagawa Prf., Japan; NPN 1113, Nagano Prf., Japan; NPN 1123, 1124, Nara Prf., Japan (five males and seven females).
Rana tsushimensis: NPN 297-302, Tsushima Is., Nagasaki Prf., Japan (three males and three females).
Rana ulma: NPN 001, 002, 006, 008, 010-012, 023, 112, 119, 121, 122, 243, Okinawajima Is., Okinawa Prf., Japan (six males and seven females).
Microhyla okinavensis: NPN 035-038, 1136-1139, Okinawajima Is., Okinawa Prf., Japan (three males and five females).
Buergeria buergeri: KUZ R56887, Wakayama Prf., Japan; NPN 345, 346, 353, Oita Prf., Japan (two males and two females).
Buergeria japonica: NPN 024, 026-029, 1131, 1132, Okinawajima Is., Okinawa Prf., Japan (three males and four females).
Buergeria robusta: NPN 146, 550, Taipei Co., Taiwan (one male and one female).
Polypedates leucomystax: NPN 019, 020, 042, 043, 1125, 1126, 1129, 1130, 1133, Okinawajima Is., Okinawa Prf., Japan (three males and six females).
Rhacophorus arboreus: NPN 204, 205, Kanagawa Prf., Japan (two males).
Rhacophorus schlegelii: NPN 079, Nara Prf., Japan; NPN 196, 203, Shizuoka Prf., Japan (one male and two females).
Rhacophorus owstoni: NPN 113, 320, 387, Iriomotejima Is., Okinawa Prf., Japan (two males and one female).
Rhacophorus viridis amamiensis: NPN 136, 137, 139, Amamioshima Is., Kagoshima Prf., Japan (two males and one female).
Rhacophorus viridis viridis: NPN 004, 005, 039, 040, 222, 225-227, 367, 371, Okinawajima Is., Okinawa Prf., Japan (five males and five females).
Kurixalus eiffingeri: NPN 319, Ishigakijima Is., Okinawa Prf., Japan; NPN 318, Iriomotejima Is., Okinawa Prf., Japan (one male and one female).
Hynobius nigrescens: NPN 1140, Locality and gender unknown.
Hynobius lichenatus: NPN 1141, Locality and gender unknown.
Cynops ensicauda: NPN 025, 314, 315, Okinawajima Is., Okinawa Prf., Japan (one male and two females).
Cynops pyrrhogaster: NPN 303, 304, Kagoshima Prf., Japan (one male and one female).
Echinotriton andersoni: KUZ R72424, R72425, Okinawajima Is., Okinawa Prf., Japan (two females).
