Research Article |
Corresponding author: Zhi-Tong Lyu ( lvzht@foxmail.com ) Corresponding author: Ying-Yong Wang ( wangyy@mail.sysu.edu.cn ) Academic editor: Raffael Ernst
© 2022 Zhi-Tong Lyu, Jian Wang, Zhao-Chi Zeng, Lin Luo, Yan-Wu Zhang, Chun-Peng Guo, Jin-Long Ren, Shuo Qi, Yun-Ming Mo, Ying-Yong Wang.
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:
Lyu Z-T, Wang J, Zeng Z-C, Luo L, Zhang Y-W, Guo C-P, Ren J-L, Qi S, Mo Y-M, Wang Y-Y (2022) Taxonomic clarifications on the floating frogs (Anura: Dicroglossidae: Occidozyga sensu lato) in southeastern China. Vertebrate Zoology 72: 495-512. https://doi.org/10.3897/vz.72.e80019
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The recognition for the floating frogs’ genus Occidozyga is in controversy for decades, and the species diversity of these frogs has recently been considered to be underestimated. In southeastern China, two floating frog species are currently recorded, namely Occidozyga lima and Occidozyga martensii. However, their current taxonomic statuses are unresolved after a series of recent taxonomic revisions. In this work, we perform morphological examinations and phylogenetic analyses on these two recorded floating frogs from southeastern China, to clarify their current taxonomic placements. The population previously recorded as Occidozyga lima should be re-assigned to the nomenclature Occidozyga obscura comb. nov., and the population previously recorded as Occidozyga martensii should be an undescribed species which is erected as Occidozyga lingnanica sp. nov. in this work.
Diversity, Generic recognition, Occidozyga lingnanica sp. nov., Occidozyga obscura comb. nov., Phrynoglossus
The floating frog subfamily Occidozyginae Fei, Ye & Huang, 1990 was originally established as a subfamily under the family Ranidae Batsch, 1796 (
Different generic affiliations for the congeners of Occidozyga sensu lato in several important revisions, and the subclade assignment in this study. NA: species was not involved in the relative revision.
Species original nomen | Authorship |
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Subclade in this study | References for morphological characters |
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Rana lima | Gravenhorst, 1829 | Occidozyga | Occidozyga | Occidozyga | I: Occidozyga sensu stricto |
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Houlema obscura | Gray, 1831 | NA | NA | NA | I: Occidozyga sensu stricto |
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Rana rhacoda | Inger, Boeadi & Taufik, 1996 | NA | NA | NA | II |
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Occidozyga berbeza | Matsui, Nishikawa, Eto, Hamidy, Hossman & Fukuyama, 2021 | NA | NA | NA | II |
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Occidozyga shiwandashanensis | Chen, Peng, Liu, Huang, Liao & Mo, 2022 | NA | NA | NA | III | This study |
Oreobatrachus baluensis | Boulenger, 1896 | Occidozyga | Phrynoglossus | Oreobatrachus | IV: Oreobatrachus |
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Micrixalus diminutiva | Taylor, 1922 | Occidozyga | Phrynoglossus | Frethia | IV: Oreobatrachus |
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Microdiscopus sumatranus | Peters, 1877 | Occidozyga | Phrynoglossus | Phrynoglossus | V: Microdiscopus |
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Oxyglossus laevis | Günther, 1858 | Occidozyga | Phrynoglossus | Frethia | VI: Frethia |
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Micrixalus magnapustulosus | Taylor & Elbel, 1958 | Occidozyga | Phrynoglossus | Phrynoglossus | VIII: Phrynoglossus | Taylor & Elbel 1958; |
Phrynoglossus myanhessei | Köhler, Vargas, Than & Thammachoti, 2021 | NA | Phrynoglossus | NA | VIII: Phrynoglossus |
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Phrynoglossus swanbornorum | Trageser, Al-Razi, Maria, Nobel, Asaduzzaman & Rahman, 2021 | NA | NA | NA | VIII: Phrynoglossus |
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Occidozyga lingnanica | Lyu & Wang sp. nov. | NA | NA | NA | VIII: Phrynoglossus | This study |
Phrynoglossus martensii | Peters, 1867 | Occidozyga | Phrynoglossus | Phrynoglossus | VIII: Phrynoglossus |
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Ooeidozyga celebensis | Smith, 1927 | Occidozyga | Phrynoglossus | Frethia | NA |
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Oxydozyga floresiana | Mertens, 1927 | Occidozyga | Phrynoglossus | Frethia | NA |
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Ooeidozyga semipalmata | Smith, 1927 | Occidozyga | Phrynoglossus | Frethia | NA |
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Occidozyga tompotika | Iskandar, Arifin & Rachmanasah, 2011 | NA | Phrynoglossus | Frethia | NA |
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As the earliest introduced genus and also the type genus of Occidozyginae, Occidozyga was erected with its type species Rana lima (Kuhl & Van Hasselt 1822;
Despite the continuous controversy on the generic recognitions, taxonomic studies on species level of Occidozyga floating frogs are relatively stagnant, until recent years.
In southeastern China where includes the subdivisions of Guangdong, Hong Kong, Macao, Fujian, and Hainan, two Occidozyga floating frog species are currently recorded, i.e. O. lima and O. martensii (
Thirty-two newly collected samples of Occidozyga floating frogs were used in this study, encompassing 9 samples previously recorded as O. lima, and 23 samples previously recorded as O. martensii. Additional three samples of species of Dicroglossinae are used as outgroups (Table
Localities, vouchers, and GenBank accession numbers for all samples used in this study.
ID | Species | Voucher | Locality | 16s | CO1 |
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1 | Occidozyga lima | Alive individual | Indonesia: Java | AB530619 | / |
2 | O. cf. lima | JBS 5405 | Myanmar: Mandalay: Na Htoe Gyi | MG935923 | MG935629 |
3 | O. cf. lima | USNM 520376 | Myanmar: Sagaing: Chatthin | MG935924 | MG935630 |
4 | O. cf. lima | SMF 103817 | Myanmar: Naypyidaw: near Yamethin | MW217494 | / |
5 | O. cf. lima | CAS 213254 | Myanmar: Yangon: Hlaw Ga Park | DQ283224 | / |
6 | O. cf. lima | SMF 103815 | Myanmar: Yangon: near Taw Hlan village | MW217492 | / |
7 | O. cf. lima | USNM 586924 | Myanmar: Tanintharyi: Yeybu village | MG935925 | MG935631 |
8 | O. cf. lima | MNHN 0086Y | Thailand: Prachuap Khiri Khan: Huay Yang NP | KR827958 | / |
9 | O. cf. lima | SMF GK7721 | Thailand: Rayong: near Rayong | MW217498 | / |
10 | O. cf. lima | MNHN 2003.0327 | Cambodia: Pouthisat: Pneum Kravanh | KR827959 | KR087831 |
11 | O. cf. lima | MNHN T2814 | Laos: Louangphrabang: Luang Prabang | KR827960 | KR087832 |
12 | O. obscura comb. nov. |
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China: Guangdong: Mt Danxia | ON615073 | ON615613 |
13 | O. obscura comb. nov. |
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China: Guangdong: Yingde | ON615066 | ON615606 |
14 | O. obscura comb. nov. |
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China: Guangdong: Yingde | ON615067 | ON615607 |
15 | O. obscura comb. nov. |
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China: Guangdong: Yingde | ON615068 | ON615608 |
16 | O. obscura comb. nov. |
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China: Guangdong: Yingde | ON615069 | ON615609 |
17 | O. obscura comb. nov. |
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China: Guangdong: Yingde | ON615070 | ON615610 |
18 | O. obscura comb. nov. |
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China: Guangdong: Yingde | ON615071 | ON615611 |
19 | O. obscura comb. nov. |
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China: Guangdong: Yingde | ON615072 | ON615612 |
20 | O. obscura comb. nov. |
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China: Guangxi: Guiping | ON615074 | ON615614 |
21 | O. lingnanica sp. nov. |
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China: Guangdong: Shenzhen | ON615075 | ON615615 |
22 | O. lingnanica sp. nov. |
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China: Guangdong: Shenzhen | ON615076 | ON615616 |
23 | O. lingnanica sp. nov. |
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China: Guangdong: Shenzhen | ON615077 | ON615617 |
24 | O. lingnanica sp. nov. |
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China: Guangdong: Shenzhen | ON615078 | ON615618 |
25 | O. lingnanica sp. nov. |
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China: Guangdong: Shenzhen | ON615079 | ON615619 |
26 | O. lingnanica sp. nov. |
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China: Guangdong: Shenzhen | ON615080 | ON615620 |
27 | O. lingnanica sp. nov. |
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China: Guangdong: Xinyi | ON615081 | ON615621 |
28 | O. lingnanica sp. nov. |
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China: Guangdong: Xinyi | ON615082 | ON615622 |
29 | O. lingnanica sp. nov. |
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China: Guangdong: Xinyi | ON615083 | ON615623 |
30 | O. lingnanica sp. nov. |
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China: Guangdong: Zhanjiang | ON615084 | ON615624 |
31 | O. lingnanica sp. nov. |
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China: Guangdong: Zhanjiang | ON615085 | ON615625 |
32 | O. lingnanica sp. nov. |
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China: Guangdong: Zhuhai | ON615086 | ON615626 |
33 | O. lingnanica sp. nov. |
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China: Guangdong: Zhuhai | ON615087 | ON615627 |
34 | O. lingnanica sp. nov. |
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China: Hainan: Changjiang | ON615096 | ON615636 |
35 | O. lingnanica sp. nov. |
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China: Hainan: Changjiang | ON615097 | ON615637 |
36 | O. lingnanica sp. nov. |
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China: Hainan: Mt Diaoluo | ON615095 | ON615635 |
37 | O. martensii sensu stricto | Not given | Malaysia: Kuala Lumpur | AB488903 | / |
38 | O. martensii sensu stricto | USNM 586941 | Myanmar: Tanintharyi, Yeybu village | MG935929 | MG935635 |
39 | O. martensii sensu stricto | USNM 586942 | Myanmar: Tanintharyi, Yeybu village | MG935941 | MG935647 |
40 | O. martensii sensu stricto | CUMZ PT2634 | Thailand: Bangkok: Bangkok | MW217475 | / |
41 | O. martensii sensu stricto | KUHE 19790 | Thailand: Chachoengso | KP318725 | / |
42 | O. martensii sensu stricto | SMF GK7349 | Thailand: Chonburi: Ya Teng Homestay | MW217491 | / |
43 | O. martensii sensu stricto | MNHN P324 | Thailand: Phangnga: Sa Nang Manora | KR827986 | KR087857 |
44 | O. martensii sensu stricto | Alive idividual | Thailand: Ranong | AB530610 | / |
45 | O. martensii sensu stricto | FMNH 266020 | Thailand: Sa Kaeo | MW007312 | / |
46 | O. martensii sensu stricto | CUMZ PT2754 | Thailand: Songkhla: Wang Pha | MW217483 | / |
47 | O. martensii sensu stricto | CUMZ PT2755 | Thailand: Songkhla: Wang Pha | MW217482 | / |
48 | O. martensii sensu stricto | FMNH 268335 | Thailand: Surat Thani | MW007314 | / |
49 | O. martensii sensu stricto | FMNH 268805 | Thailand: Krabi | MW007315 | / |
50 | O. martensii sensu stricto | SMF GK7713 | Thailand: Trat: Ko Kut Resort | MW217505 | / |
51 | O. martensii sensu stricto | SMF GK7695 | Thailand: Trat: Trat | MW217504 | / |
52 | O. martensii L1 |
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China: Yunnan: Jinghong | ON615088 | ON615628 |
53 | O. martensii L1 |
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China: Yunnan: Jinghong | ON615089 | ON615629 |
54 | O. martensii L1 |
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China: Yunnan: Mengla | ON615090 | ON615630 |
55 | O. martensii L1 |
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China: Yunnan: Mengla | ON615091 | ON615631 |
56 | O. martensii L1 |
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China: Yunnan: Mengla | ON615092 | ON615632 |
57 | O. martensii L1 |
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China: Yunnan: Menglian | ON615093 | ON615633 |
58 | O. martensii L1 |
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China: Yunnan: Menglian | ON615094 | ON615634 |
59 | O. martensii L1 | SCUM H020 | China | DQ458254 | / |
60 | O. martensii L1 | MNHN 2004.0357 | Laos: Phongsali: Buon Tai | KR827983 | KR087854 |
61 | O. martensii L1 | CUMZ PT0167 | Thailand: Chaiyaphume: Ban Na Si Nuan | MW217484 | / |
62 | O. martensii L1 | CUMZ PT1543 | Thailand: Chiang Mai: Huai Hong Khrai | MW217477 | / |
63 | O. martensii L1 | CUMZ PT1544 | Thailand: Chiang Mai: Huai Hong Khrai | MW217476 | / |
64 | O. martensii L1 | MNHN 0119Y | Thailand: Phetchabun: Thung Salaeng Luang | KR827985 | KR087856 |
65 | O. martensii L1 | MNHN 0026Y | Thailand: Uttaradit: Nam Pad district | KR827984 | KR087855 |
66 | O. martensii L2 | JBS 19932 | Myanmar: Yangon: Mingalardon | MG935921 | MG935627 |
67 | O. martensii L2 | USNM 587386 | Myanmar: Yangon: Mingalardon | MG935914 | MG935620 |
68 | O. martensii L2 | USNM 587389 | Myanmar: Yangon: Mingalardon | MG935919 | MG935625 |
69 | O. swanbornorum | JnUZool-A0719 | Bangladesh: Chattogram | MN705433 | / |
70 | O. swanbornorum | JnUZool-A0819 | Bangladesh: Chattogram | MN705434 | / |
71 | O. swanbornorum | JnUZool-A0919 | Bangladesh: Chattogram | MN705435 | / |
72 | O. swanbornorum | JnUZool-A1019 | Bangladesh: Chattogram | MN705436 | / |
73 | O. swanbornorum | JnUZool-A1117 | Bangladesh: Chattogram | MN705437 | / |
74 | O. magnapustulosus | MNHN 712D | Laos: Vientiane: Viangchan | KR827981 | KR087852 |
75 | O. magnapustulosus | FMNH 255134 | Laos: Champasak: Mounlapamok | MW007295 | / |
76 | O. magnapustulosus | NKMA 2196-15 | Thailand: Kalasin | MW007297 | / |
77 | O. magnapustulosus | SMF GK7855 | Thailand: Nakhon Phanom: Ban Kan Luang | MW217490 | / |
78 | O. magnapustulosus | SMF GK7396 | Thailand: Roi Et: near Ban Sa At Na Di | MW217487 | / |
79 | O. magnapustulosus | SMF GK7532 | Thailand: Sakon Nakhon: Ban Phaeng Yai | MW217486 | / |
80 | O. magnapustulosus | SMF GK7533 | Thailand: Sakon Nakhon: Ban Phaeng Yai | MW217485 | / |
81 | O. magnapustulosus | FMNH 261789 | Cambodia: Koh Kong | MW007298 | / |
82 | O. myanhessei | USNM 587105 | Myanmar: Bago: Dawei | MG935916 | MG935622 |
83 | O. myanhessei | USNM 587107 | Myanmar: Bago: Dawei | MG935920 | MG935626 |
84 | O. myanhessei | SMF 103800 | Myanmar: Magwe: near Taungdwingyi | MW217503 | / |
85 | O. myanhessei | SMF 103840 | Myanmar: Yangon: East Yangon University | MW217499 | / |
86 | O. myanhessei | SMF 103841 | Myanmar: Yangon: East Yangon University | MW217500 | / |
87 | O. myanhessei | USNM 587402 | Myanmar: Yangon: Mingalardon | MG935917 | MG935623 |
88 | O. shiwandashanensis | NNU 202103284 | China: Guangxi: Mt Shiwandashan | MZ747455 | / |
89 | O. shiwandashanensis | NNU 202103285 | China: Guangxi: Mt Shiwandashan | MZ747456 | / |
90 | O. shiwandashanensis | NNU 202103320 | China: Guangxi: Mt Shiwandashan | MZ747457 | / |
91 | O. shiwandashanensis | NNU 202103321 | China: Guangxi: Mt Shiwandashan | MZ747458 | / |
92 | O. berbeza | KUHE 17327 | Malaysia: Sarawak: Matang | LC593607 | / |
93 | O. berbeza | KUHE 17327 | Malaysia: Sarawak: Matang | LC593609 | / |
94 | O. berbeza | KUHE 17327 | Malaysia: Sarawak: Matang | LC593610 | / |
95 | O. rhacoda complex | NMBE 1064176 | Malaysia: Sarawak: Kubah NP | MW007293 | / |
96 | O. rhacoda complex | NMBE 1065363 | Malaysia: Sarawak: Gunung Penrissen | MW007173 | / |
97 | O. rhacoda complex | NMBE 1061694 | Malaysia: Sarawak: Gunung Murud | MW007275 | / |
98 | O. rhacoda complex | NMBE 1066057 | Malaysia: Sarawak: Payeh Maga | MW007281 | / |
99 | O. rhacoda complex | NMBE 1069835 | Malaysia: Sarawak: Usun Apau | MW007274 | / |
100 | O. rhacoda complex | NMBE 1074010 | Malaysia: Sarawak: Batang Ai | MW007290 | / |
101 | O. laevis complex | NMBE 1072307 | Malaysia: Sabah: Danum Valley Conservation Area | MW007227 | / |
102 | O. laevis complex | FMNH 234895 | Malaysia: Sabah: Sipitang | MW007219 | / |
103 | O. laevis complex | NMBE1072456 | Malaysia: Sabah: Tawau Hills NP | MW007254 | / |
104 | O. laevis complex | NMBE 1056418 | Malaysia: Sarawak: Gunung Mulu NP | MW007217 | / |
105 | O. laevis complex | KU 310493 | Philippinen: Eastern Samar: Taft | MW007237 | / |
106 | O. laevis complex | FMNH 259486 | Philippinen: Kalinga: Balbalasang | MW007236 | / |
107 | O. laevis complex | KU 306652 | Philippinen: Negros Oriental: Valencia | MW007235 | / |
108 | O. laevis complex | PNM 7446 | Philippinen: Quezon: Lao | AY313684 | / |
109 | O. laevis complex | KU 302276 | Philippinen: Romblon: Magdiwang | MW007234 | / |
110 | O. laevis complex | EMD 424 | Philippines: Agusan Del Norte | MT820178 | / |
111 | O. laevis complex | PNM ACD2011 | Philippines: Isabela | MT820166 | / |
112 | O. laevis complex | KU 302322 | Philippines: Oriental Mindoro | MT820171 | / |
113 | O. laevis complex | KU 308966 | Philippines: Palawan: Irawan | MW007231 | / |
114 | O. laevis complex | PNM ACD5414 | Philippines: South Cotobato | MT820170 | / |
115 | O. laevis complex | KU 306301 | Philippines: Western Samar | MT820173 | / |
116 | O. laevis complex | KU 314471 | Philippines: Zamboanga: Pasonanca | MT820168 | / |
117 | Occidozyga sp. | USNM 586929 | Myanmar: Tanintharyi: Yeybu village | MG935915 | MG935621 |
118 | Occidozyga sp. | USNM 586928 | Myanmar: Tanintharyi: Yeybu village | MG935922 | MG935628 |
119 | O. sumatrana complex | MZB Amph 16392 | Indonesia: Java | LC593611 | / |
120 | O. sumatrana complex | MZB RMB2134 | Indonesia: Java | MT820186 | / |
121 | O. sumatrana complex | Not given | Indonesia: Sumatra: Bukit Barisan Selatan NP | MW007270 | / |
122 | O. sumatrana complex | Not given | Indonesia: Sumatra: Hutan Harapan | MW007273 | / |
123 | O. sumatrana complex | Not given | Indonesia: Sumatra: Hutan Harapan | MW007269 | / |
124 | O. sumatrana complex | FRIM 1136 | Malaysia: Pahang: Bukit Rengit | MT820183 | / |
125 | O. sumatrana complex | FMNH 267890 | Malaysia: Sarawak: Bintulu | MW007260 | / |
126 | O. sumatrana complex | FMNH 269753 | Malaysia: Sarawak: Binyo-Penyilam | MW007268 | / |
127 | O. sumatrana complex | FRIM 1132 | Malaysia: Selangor: Kepong | MT820181 | / |
128 | O. baluensis complex | NMBE 1072541 | Malaysia: Sabah: Danum Valley Conservation Area | MW007193 | / |
129 | O. baluensis complex | FMNH 235605 | Malaysia: Sabah: Kota Marudu | MW007178 | / |
130 | O. baluensis complex | FMNH 242747 | Malaysia: Sabah: Sipitang | DQ283143 | / |
131 | O. baluensis complex | FMNH273695 | Malaysia: Sarawak: Bintulu | MW007215 | / |
132 | O. baluensis complex | NMBE 1064771 | Malaysia: Sarawak: Gunung Mulu NP | MW007177 | / |
133 | O. baluensis complex | NMBE 1073926 | Malaysia: Sarawak: Payeh Maga | MW007211 | / |
134 | O. baluensis complex | Not given | Malaysia: Sarawak: Pelagus NP | MW007175 | / |
135 | O. baluensis complex | Not given | Malaysia: Sarawak: Pelagus NP | MW007216 | / |
136 | O. diminutiva | KU 321225 | Philippines: Mindanao: Zamboanga: Pasonanca | MT820199 | / |
137 | O. diminutiva | KU 321226 | Philippines: Mindanao: Zamboanga: Pasonanca | MT820200 | / |
138 | O. diminutiva | KU 321227 | Philippines: Mindanao: Zamboanga: Pasonanca | MT820201 | / |
139 | Ingerana tenasserimensis | USNM 587302 | Myanmar: Mon: Kyaikhtiyo Wildlife Sanctuary | MG935840 | MG935546 |
140 | Ingerana tenasserimensis | USNM 586921 | Myanmar: Tanintharyi: Yeybu village | MG935837 | MG935543 |
141 | Hoplobatrachus rugulosus |
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China: Guangdong: Mt Danxia | ON615100 | ON615640 |
142 | Nanorana parkeri |
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China: Tibet: Jiacha | ON615099 | ON615639 |
143 | Quasipaa shini |
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China: Guangxi: Mt Dayao | ON615098 | ON615638 |
For phylogenetic analyses, 108 additional sequences of floating frogs species were obtained from GenBank and incorporated into our dataset (Table
Thirty-one newly collected samples of Occidozyga floating frogs were used in this study, encompassing 10 specimens previously recorded as O. lima, and 21 samples previously recorded as O. martensii. Detailed collection data for these specimens are given in the Taxonomic accounts. Abbreviations for museums are
External measurements were made on the examined specimens, using digital calipers (Neiko 01407A Stainless Steel 6-Inch Digital Caliper) to the nearest 0.1 mm, including snout–vent length (SVL) from the tip of snout to posterior margin of the vent, head length (HDL) from the tip of snout to the articulation of the jaw, head width (HDW) at the commissure of the jaws, snout length (SNT) from the tip of snout to the anterior corner of the eye, internasal distance (IND), the shortest interorbital distance between the upper eyelids (IOD), eye diameter (ED) from the anterior corner of the eye to posterior corner of the eye, hand length (HND) from the proximal border of the outer palmar tubercle to the tip of digit III, radioulna length (RAD) from the flexed elbow to the proximal border of the outer palmar tubercle, foot length (FTL) from the distal end of the shank to the tip of digit IV, and tibial length (TIB) from the outer surface of the flexed knee to the heel.
The BI and ML analyses resulted in identical topologies (Fig.
As illustrated in the phylogenetics, all samples of genus Occidozyga sensu lato gather together in a clade with Bayesian posterior probabilities (BPP) = 1.00 and ML bootstrap supports (BS) = 100, forming the sister taxon to the other genus Ingerana Dubois, 1987 within the subfamily. The clade of Occidozyga sensu lato can be further divided into eight subclades, however, the phylogenetic relationships among these eight subclades remain unresolved due to the weak supports.
All samples previously recorded as O. lima formed the subclade I, which represents the concept of “Occidozyga sensu stricto” (BPP=1.00, BS=100). This subclade was composed of three lineages. The single sample from the type locality of O. lima in Java, Indonesia (ID 1 in Figs
All samples previously recorded as O. martensii were seated in the subclade VIII (BPP=1.00, BS=100) which represents the concept of “Phrynoglossus”. This subclade was composed of seven lineages. Three lineages VIII-1, VIII-3, and VIII-4 were corresponding to three recognized species O. myanhessei comb. nov. (BPP=1.00, BS=98), O. swanbornorum comb. nov. (BPP=1.00, BS=100), and O. magnapustulosa (Taylor & Elbel, 1958) (BPP=1.00, BS=99), respectively. Samples in the remaining four lineages were all previously recorded as O. martensii (actually O. myanhessei comb. nov. and O. swanbornorum comb. nov. were also recorded as O. martensii for decades and just recognized recently), however, they were paraphyletic. The sample from the type locality of O. martensii in Bangkok, Thailand (ID 40 in Figs
The inner relationships for the other subclades of Occidozyga sensu lato were also complicated. Subclade II (BPP=1.00, BS=90) included samples of O. berbeza (ID 92–94) and O. rhacoda (ID 95–100), while the samples identified as O. rhacoda were paraphyletic and separated into three distinct lineages. Furthermore, a sample of O. rhacoda (ID 95) was indeed conspecific with samples of O. berbeza. The most recently described species O. shiwandashanensis (ID 88–91) formed a monotypic subclade III (BPP=1.00, BS=100). Subclade IV (BPP=1.00, BS=100) included samples of O. baluensis (ID 128–135) and O. diminutiva (ID 136–138), while the samples identified as O. baluensis were paraphyletic and separated into three distinct lineages too, indicating that this species should be a species complex. Samples identified as O. sumatrana (ID 119–127) and O. laevis (ID 101–116) formed the subclade V (BPP=0.99, BS=89) and subclade VI (BPP=1.00, BS=100) respectively, however, distinct deep divergences were presented in these two subclades. The remaining subclade VII (BPP=1.00, BS=100) was consist of two unknown samples from peninsular Myanmar.
In this work, it is the first time to integrate the molecular data of floating frogs published in recent years (e.g.
Particularly, since there are distinct morphological differences among some of these subclades (especially between the “Phrynoglossus” and “Occidozyga sensu stricto” subclades), we speculate that Occidozyga sensu lato would be partitioned into multiple genera after comprehensive phylogenetic analyses and detailed morphological re-examination in the future.
The species diversity of floating frogs is dramatically underestimated as indicated in our analysis. Deep divergences are presented among the samples currently identified as O. rhacoda, and similar situations are also revealed in those of O. baluensis, O. sumatrana, and O. laevis. Therefore, these four species are all tentatively designated as species complex in this work, and further clarifications with morphological study are required. Particularly, the relationship between O. rhacoda and O. berbeza are still unclear, and the data from the topotype of O. rhacoda are required to settle this puzzle.
Within subclade I (“Occidozyga sensu stricto” subclade), similar to the result by
Within subclade VIII (“Phrynoglossus” subclade), the samples previously recorded as O. martensii are paraphyletic into four different lineages, among which the relationships are also unresolved, due to the weak support values. The lineage VIII-5 of O. martensii sensu stricto involves populations throughout southern and peninsular Thailand, peninsular Myanmar, and peninsular Malaysia (ID 37–51). The lineage VIII-7 for the population from Guangdong and Hainan, southeastern China (ID 21–36) is considered to be an undescribed species of the genus Occidozyga, based on the phylogenetic results and the morphological differences (see below in Taxonomic accounts). Because of the unstable supported values (BS=87) and inadequate specimens, the taxonomic status for the lineage VIII-6 of O. martensii L1 is not defined in this work. This lineage might be close to the nomen Oxyglossus laevis var. vittata Andersson, 1942 and further study is in preparation. The lineage VIII-2 of O. martensii L2 seems to represent another cryptic species, calling for detailed morphological examinations on the related specimens.
Houlema obscura
Oxyglossa lima var. chinens
Oxydozyga lima
—
Osteosternum amoyense
Ooeidozyga lima
—
Occidozyga lima
—
Holotype.
Seven adult males and three adult females. Males
The specific name obscura means ‘obscure’ in Latin.
“Chinese floating frog” in English / “中国浮蛙 (zhōng guó fú wā)” in Chinese.
(1) Body stocky, size small, SVL 24.2–27.5 mm in adult males (n=7) and 31.5–32.2 mm in adult females (n=3); (2) snout short triangular shaped; (3) nostrils located dorsally; (4) eye orientation vertically; (5) loreal region oblique, not concave or convex; (6) interorbital space narrower than internarial distance; (7) tongue narrow and slender, unnotched, pointed distally, lingual papilla absent; (8) vomerine ridge and vomerine teeth absent; (9) supratympanic fold distinct, raised, and granulated, curved on the temporal region; (10) tympanum hidden, edge invisible; (11) fingers with rudimentary webs, toes with full webs; (12) heels not meeting, tibio-tarsal articulation reaching between the posterior and anterior of the eye.
Occidozyga obscura comb. nov. was previously synonymized with O. lima. These two species are most similar to each other. However, Occidozyga obscura comb. nov. can be distinguished by the combination of the following characteristics: loreal region oblique, not concave or convex (vs. slightly concave in O. lima), interorbital space narrower than internarial distance (vs. subequal), supratympanic fold distinct, raised, and granulated (vs. indistinct), inner metatarsal tubercle large and raised (vs. weakly projecting), and tibio-tarsal articulation reaching between the posterior and anterior of the eye (vs. reaching tip of nostril).
Occidozyga obscura comb. nov. furthers differs from O. berbeza by the supratympanic fold curved on the temporal region (vs. straight), fingers with rudimentary webs (vs. unwebbed), and outer metatarsal tubercle present (vs. absent). O. obscura comb. nov. distinctly differs from O. rhacoda by the dorsolateral fold absent (vs. present), and fingers with rudimentary webs (vs. unwebbed).
Occidozyga obscura comb. nov. can be easily distinguished from the remaining 13 congeners O. baluensis, O. celebensis, O. diminutiva, O. floresiana, O. laevis, O. magnapustulosa, O. martensii, O. myanhessei comb. nov., O. semipalmata, O. sumatrana, O. shiwandashanensis, O. swanbornorum comb. nov., and O. tompotika, by the tongue narrow and slender (vs. wide and swollen in all of these 13 species).
Based on the examined specimens (n=10). All specimens were similar in morphology. The measurements are given in Table
Body stocky, small-sized, SVL 24.2–27.5 mm (n=7) in males and 31.5–32.2 mm (n=3) in females. Head flat above, almost as wide as long (HDW/HDL 0.97–1.09, n=10); pineal ocellus absent; snout short triangular shaped, distinctly protruding beyond lower jaw, tip of snout rounded in dorsal view and profile; canthus rostralis absent, loreal region oblique, not concave or convex; nostril rounded, located dorsally, distinctly raised, closer to the tip of snout than to the eye; eye orientation vertically, pupil diamond shaped; interorbital space narrower than internarial distance; tympanum hidden, edge invisible; vomerine ridge and teeth absent; tongue narrow and slender, unnotched, pointed distally, lingual papilla absent.
Measurements (in mm) of the examined specimens of Occidozyga obscura comb. nov.
Specimen |
|
|
|
|
|
|
|
|
|
|
Sex | Male | Male | Male | Male | Male | Male | Male | Female | Female | Female |
SVL | 24.2 | 24.7 | 27.5 | 24.3 | 26.2 | 27.0 | 24.8 | 32.2 | 32.0 | 31.5 |
HDL | 9.1 | 9.4 | 8.9 | 8.8 | 9.4 | 9.4 | 8.8 | 10.4 | 10.4 | 10.1 |
HDW | 8.8 | 9.6 | 9.7 | 8.6 | 9.4 | 9.3 | 8.6 | 11.0 | 11.4 | 10.0 |
SNT | 2.7 | 3.1 | 3.3 | 2.8 | 3.3 | 3.1 | 3.2 | 4.2 | 4.0 | 3.7 |
IND | 1.5 | 1.3 | 1.6 | 1.4 | 1.4 | 1.5 | 1.2 | 1.6 | 1.5 | 1.6 |
IOD | 1.5 | 1.2 | 1.5 | 1.3 | 1.4 | 1.4 | 1.1 | 1.5 | 1.4 | 1.4 |
ED | 3.2 | 2.8 | 2.7 | 2.7 | 2.8 | 2.9 | 2.6 | 3.1 | 3.0 | 3.2 |
HND | 7.7 | 7.5 | 7.8 | 7.1 | 7.3 | 7.4 | 6.6 | 8.2 | 8.8 | 8.5 |
RAD | 4.0 | 4.5 | 3.6 | 4.1 | 4.4 | 4.0 | 3.9 | 4.9 | 5.1 | 4.9 |
FTL | 19.3 | 18.4 | 18.4 | 18.0 | 18.8 | 18.8 | 17.5 | 21.3 | 21.5 | 21.6 |
TIB | 11.3 | 11.4 | 11.2 | 11.1 | 11.7 | 11.5 | 10.9 | 13.4 | 13.6 | 12.8 |
Forelimbs short, lower arm 13–18% (n=10) of SVL and hand 26–32% (n=10) of SVL; fingers distinctly thin and long, relative finger lengths I<II<IV<III; tips of fingers pointed, not dilated, and without disks; distinct lateral fringes on inner and outer sides of each finger, fingers with rudimentary webs, more distinct between fingers I and II; subarticular tubercles present at the bases of each finger, prominent and rounded; supernumerary tubercles absent; inner and outer palmar tubercles prominent and rounded.
Hind limbs robust, tibia 41–47% (n=8) of SVL and foot 66–80% (n=8) of SVL; heels not meeting when hind limbs flexed at right angles to the axis of the body; tibio-tarsal articulation reaching between the posterior and anterior of the eye when hind limb is stretched along the side of the body; toes distinctly long and thin, relative lengths I<II<III<V<IV; tips of toes pointed, dilated into pear-shaped disks; toes with full webs, metatarsal web present, distinct lateral fringes on lateral edges of toes I and V; subarticular tubercles rounded, prominent; inner metatarsal tubercle large and long-elliptic, slightly raised, length twice the width; outer metatarsal tubercle relatively smaller than the inner metatarsal tubercle, distinctly raised and pointed, length slightly larger than width; inner tarsal fold relatively flat, in contact with the inner metatarsal tubercle; tarsal tubercle large and distinctly raised, close to the tibio-tarsal articulation.
Dorsal surface relatively rough, transverse wrinkles and dense tubercles on the dorsum, head, flanks, and limbs; small granules on the dorsal rears of hands and tarsi; not bearing spinules on the dorsal skin; supratympanic fold distinct, raised and granulated, extending from the posterior corner of the eye, curved on the temporal region, to the previous shoulder; dorsolateral fold absent. Ventral surface with large flattened tubercles, denser on the throat and thighs; dense granules on the ventral feet and tarsi.
In life (Fig.
In preservative (Fig.
Morphological features of Occidozyga obscura comb. nov. and Occidozyga lingnanica sp. nov. in preservative. Occidozyga obscura comb. nov.: A adult male
Male with a single subgular vocal sac; in breeding season, a single, light grey nuptial pad on the dorsal surface of finger I, nuptial spinules invisible. Males (SVL 24.2–27.5 mm) distinctly smaller than females (SVL 31.5–32.2 mm) (Fig.
This frog inhabits natural or artificial ponds and paddy fields in plain areas. They quickly dive underwater after being disturbed during the daytime, while become relatively insensitive at night. Males call in the water surface or waterside grass from dusk to dawn, more active during the rain. The breeding season is from April to August (this study;
Occidozyga obscura comb. nov. can be recognized from several localities of Guangdong and Guangxi, southeastern China (Figs
This species was previously reported as common and widespread species in southeastern China under the nomen O. lima, but its population quantity is found rapidly declining due to the influence of human activities such as pesticide abuse and urban construction. The populations in Hong Kong, Macao, Shenzhen, Guangzhou, and Xiamen might disappear, as no more reports and vouchers in nearly 20 years (this study;
The type specimen of Occidozyga obscura comb. nov. was collected by John Reeves (1774–1856) but the exact type locality was not given in the original description (
Moreover, there were two historic species currently regarded as synonymies of O. lima, namely Oxyglossa lima var. chinens and Osteosternum amoyense (
Ooeidozyga laevis martensi
—
Occidozyga martensii
—
Phrynoglossus martensii
—
Holotype.
Five adult males and five adult females. Male
The specific name lingnanica refers to the lingnan region, a geographic area covering Guangdong, Guangxi, and Hainan in southeastern China, where this new frog species occurs in. This specific name is also dedicated to the former Lingnan University (1888–1952) that was incorporated into Sun Yat-sen University after 1953.
“Lingnan floating frog” in English / “岭南浮蛙 (lǐng nán fú wā)” in Chinese.
(1) Body stocky, size small, SVL 19.9–22.1 mm in males (n=8) and 26.8–28.8 mm in females (n=3); (2) snout short triangular shaped; (3) nostrils located laterally; (4) eye orientation laterally; (5) canthus rostralis visible, rounded; (6) loreal region vertical, not concave/convex; (7) tongue wide and swollen, unnotched, rounded distally, lingual papilla absent; (8) vomerine ridge and vomerine teeth absent; (9) supratympanic fold distinct and raised, slightly curved on the temporal region; (10) tympanum hidden, edge invisible; (11) relative finger lengths II=I<IV<III, relative toe lengths I<II<V<III<IV; (12) fingers without webs, toes with two third webs; (13) heels not meeting, tibio-tarsal articulation reaching at the posterior margin of supratympanic fold; (14) tarsal fold absent.
Occidozyga lingnanica sp. nov. has been long-term misidentified as O. martensii, however, it differs from the latter by a combination of the following morphological characters: tympanum hidden, edge invisible (vs. tympanum edge raised), relative finger lengths II=I<IV (vs. II=IV<I), relative toe lengths V<III (vs. III<V), tarsal fold absent (vs. present), tibio-tarsal articulation reaching the posterior margin of supratympanic fold (vs. reaching the region of eye).
Occidozyga lingnanica sp. nov. can be distinguished from the remaining three known congeners in Clade VIII (Fig.
For the remaining 13 congeners, Occidozyga lingnanica sp. nov. distinctly differs from O. lima, O. obscura comb. nov., and O. berbeza by the tongue wide and swollen (vs. narrow and slender); from O. rhacoda by the dorsolateral fold absent (vs. present); from O. shiwandashanensis by the tarsal fold absent (vs. present); from O. celebensis, O. laevis, and O. sumatrana by the eye orientation laterally (vs. vertically); from O. baluensis, O. floresiana, and O. semipalmata by the canthus rostralis rounded (vs. absent); from O. diminutiva and O. tompotika by the supratympanic fold curved (vs. straight).
Forelimbs short, lower arm 15% of SVL and hand 25% of SVL; fingers relatively thin and long, relative finger lengths II=I<IV<III; tips of fingers rounded, not dilated and without disks; fingers without webs and fringes; subarticular tubercles present at the bases of each finger, prominent and rounded; supernumerary tubercles absent; inner and outer palmar tubercles prominent and rounded.
Hind limbs robust, tibia 44% of SVL and foot 63% of SVL; heels not meeting when hind limbs flexed at right angles to the axis of the body; tibio-tarsal articulation reaching at the posterior margin of supratympanic fold when hind limb is stretched along the side of the body; toes distinctly long and thin, relative lengths I < II < V < III < IV; tips of toes rounded, dilated into rounded disks; toes with two third webs, metatarsal web present, distinct lateral fringes on lateral edges of toes I and V; subarticular tubercles rounded, prominent; inner metatarsal tubercle large and long-elliptic, distinctly raised, length triple the width; outer metatarsal tubercle absent; tarsal fold absent.
Dorsal surface relatively rough, large tubercles scattering on skin of dorsum, flanks, and dorsal limbs, not bearing spinules on the dorsal skin; a faint fold across head between orbits; supratympanic fold distinct, raised, extending from the posterior corner of the eye, slightly curved on the temporal region, to the previous shoulder; dorsolateral fold absent. Ventral surface with large flattened tubercles; a fold across breast; dense granules on the ventral tarsi.
In life (Fig.
In preservative, dorsum light gray; black speckles on dorsum and transverse bars on limbs light brown; mid-dorsal stripe grayish white and more distinct; nuptial pad light gray, slightly transparent; ventral surface grayish white; mottling on throat gray white.
The measurements of the type series are given in Table
Measurements (in mm) of the examined specimens of Occidozyga lingnanica sp. nov.
Specimen |
|
|
|
|
|
|
|
|
|
|
|
Sex | Male | Male | Male | Male | Male | Male | Male | Male | Female | Female | Female |
SVL | 22.1 | 21.6 | 21.4 | 21.5 | 19.9 | 20.2 | 21.8 | 21.7 | 26.8 | 28.5 | 28.8 |
HDL | 7.8 | 7.1 | 7.5 | 7.5 | 6.6 | 6.6 | 7.1 | 7.8 | 9.0 | 9.5 | 9.0 |
HDW | 7.4 | 6.7 | 7.2 | 7.2 | 6.5 | 6.5 | 6.6 | 7.5 | 8.9 | 9.3 | 9.0 |
SNT | 2.9 | 2.7 | 2.5 | 2.6 | 2.3 | 2.3 | 2.9 | 2.9 | 3.0 | 3.5 | 3.3 |
IND | 1.9 | 1.8 | 1.6 | 1.6 | 1.5 | 1.6 | 1.7 | 1.8 | 2.1 | 2.2 | 2.3 |
IOD | 1.5 | 1.4 | 1.1 | 1.2 | 1.0 | 1.1 | 1.3 | 1.3 | 1.7 | 1.8 | 1.9 |
ED | 2.6 | 2.5 | 2.5 | 2.5 | 2.3 | 2.3 | 2.5 | 2.7 | 3.3 | 3.4 | 3.0 |
HND | 5.4 | 5.3 | 5.3 | 5.3 | 4.7 | 4.6 | 5.5 | 5.4 | 5.6 | 6.8 | 6.1 |
RAD | 3.7 | 3.5 | 3.2 | 3.4 | 3.5 | 3.7 | 3.4 | 3.3 | 4.2 | 4.4 | 4.8 |
FTL | 14.1 | 14.4 | 13.4 | 14.2 | 12.9 | 13.8 | 14.7 | 14.1 | 17.9 | 19.2 | 19.5 |
TIB | 9.8 | 9.7 | 9.4 | 9.8 | 8.6 | 9.2 | 9.5 | 9.5 | 11.7 | 11.4 | 11.8 |
Male with a single subgular vocal sac; in breeding season, a single, light yellow, swollen, and granular nuptial pad on the dorsal surface of finger I, nuptial spinules invisible. Males (SVL 19.9–22.1 mm) distinctly smaller than females (SVL 26.8–28.8 mm) (Fig.
This frog inhabits natural or artificial ponds and paddy fields in hilly regions. Males call in the water surface or waterside grass from dusk to dawn. The breeding season is from May to August (this study;
Occidozyga lingnanica sp. nov. can be recognized from multiple localities in Guangdong and Hainan of southeastern China based on the phylogenetic result in this work (Figs
Occidozyga lingnanica sp. nov. was previously reported as common and widespread species in southeastern China under the nomen O. martensii. Nevertheless, during our repeated surveys throughout southeastern China, the population quantity of this species is found rapidly declining due to the influence of human activities such as pesticide abuse and urban construction. We recommend Occidozyga lingnanica sp. nov. to be listed as Vulnerable (VU) [IUCN Red List criteria B1b(ii)(iii)].
We thank Guangdong Yunkaishan National Nature Reserve, Guangdong Nanling National Nature Reserve, Guangdong Shimentai National Nature Reserve, Guangdong Danxiashan National Nature Reserve, Qing Du, Wei-Liang Xie, Run-Lin Li, Hai-Long He, Yong-You Zhao, and Hong-Hui Chen, for their help in the fieldwork, lab work, and manuscript preparation. We thank Gunther Köhler for his useful comments on our manuscript. This research was supported by the DFGP Project of Fauna of Guangdong-202115, the National Animal Collection Resource Center, China, the Project of Animal Diversity Survey and Monitoring System Construction of Guangdong Shimentai National Nature Reserve, and the Project of Survey of Terrestrial Vertebrate Diversity in Guangdong Danxiashan National Nature Reserve.
Table S1
Data type: .xlsx
Explanation note: Pairwise distances based on the 16S gene among all Occidozyga samples used in this study.