Herpetology Notes, volume 12: 561-564 (2019) (published online on 31 May 2019) Enhydris subtaeniata (Bourret 1934) (Serpentes: Homalopsidae): New distribution record and map Yodchaiy Chuaynkern1,*, Prateep Duengkae2, Chantip Chuaynkern1, Krit Pinthong3 and Alonglod Tanomthong1 The Mekong mud snake Enhydris subtaeniata was molecular analysis, and the specimen was fixed in described as Hypsirhina enhydris subtaeniata by 10% formaldehyde, and subsequently transferred to Bourret (1934) based on specimens from Kompong 70% alcohol. The specimen is housed in the Khon Speu, Cambodia (Lectotype: MNHN 1958.04.74; Kaen Vertebrate Collection (KKUC 01153), Khon designated by Murphy, 2007). This snake is distributed Kaen University, Khon Kaen Province, northeastern in lowland regions of central Indochina, namely in Thailand. the Middle and Lower Mekong River basins of Laos, The specimen was allocated to Enhydris subtaeniata Thailand, Vietnam and Cambodia (Voris et al., 2012). for showing morphological characteristics considered The known distributional records indicate that there is a huge distribution gap in the southern part of northeastern Thailand. This gap lies between four known localities (Fig. 1), i.e., Ubonrat Dam (Khon Kaen Province) in the northwest, Ban Badan (Nakhon Ratchasima Province) in the southwest, Tonle Sap (Cambodia) in the south, and Dong Khanthung (Lao PDR) in the southeast. In the huge area between these localities, records of Enhydris subtaeniata are lacking. We herein report on an additional record that fills this distribution gap. We captured an adult female (Figs. 2, 3) on 7 March 2015 by using a gill net in a 13-year-old private pond (15.054611, 103.691962) which is connected to the public reservoir in Baan Aayong (=Aayong village), Taen Subdistrict, Sikhoraphum District, Surin Province (Fig. 1). The snake was euthanized by injecting a nebutal overdose. Pieces of its liver were cut for further 1 Department of Biology, Faculty of Science, Khon Kaen University, Mueang Khon Kaen, Khon Kaen, 40002 Thailand. 2 Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart Figure 1. Collection localities of Enhydris subtaeniata: 1) University, Bangkok 10900, Thailand. Bung Boraphet, Nakhon Sawan Province, Thailand. 2) Ban 3 Department of Fundamental Science, Faculty of Science Badan, Nakhon Ratchasima Province, Thailand. 3) Ubonrat and Technology, Surindra Rajabhat University, Chatuchuk, Dam, Khon Kaen Province, Thailand. 4) Sikhoraphum Bangkok, 10900 Thailand. District, Surin Province, Thailand. 5) Dong Khanthung, Laos. * Corresponding author. E-mail: [email protected] 6) Tonle Sap, Cambodia. 7) U. Minh Thong, Vietnam. 562 Yodchaiy Chuaynkern et al. provincial areas, only the records from Khon Kaen, Nakhon Ratchasima, and Nakhon Sawan were based on voucher specimens. Some works reported distribution of Enhydris subtaeniata in Prachin Buri Province but did not refer to voucher specimens (see Nabhitabhata and Chan-ard, 2005; Chuaynkern and Chuaynkern, 2012; Cox et al., 2012). Voris et al. (2012) collected intensively in Prachin Buri (Kabin Buri District) but failed to record the species. Thus the occurrence of Enhydris subtaeniata in this province requires confirmation. Cox et al. (2012) included Udon Thani (northeastern Thailand) and Songkhla (southern Thailand) provinces in the distribution range of Enhydris subtaeniata, but it is likewise unclear if the records are based on voucher specimens. Figure 2. Enhydris subtaeniata (KKUC 01153; SVL 537 Most of our formal knowledge of the Thai homolopsid mm, TaiL 92.1 mm) from Baan Aayong, Taen Subdistrict, Srikhoraphum District, Surin Province, Thailand in life. snakes comes from the research of Cox (1991), Murphy (2007), Cox et al. (2012) and Chan-ard et al. (2015). Intensive surveys for obtaining additional localities and specimens are required. This is especially the case in diagnostic for the species (Cox, 1991; Murphy, 2007; northeastern Thailand. Previous works were mainly Cox et al., 2012; Voris et al., 2012; Murphy and Voris, 2014). Its morphological characteristics are as follow: snout-vent length (SVL) 537 mm; tail length (TaiL) 92.1 mm; dorsal scale rows (after Dowling, 1951) 21: 21: 19, at neck, mid-body and anal respectively; ventral scales 143; subcaudal scales 46; nasals in contact; loreal 1; preocular 1; postoculars 2; temporals 1+2; supralabials 8; infralabials 10 (Fig. 3). The morphological characteristics of the newly collected specimen is presented alongside a summary of characteristics of Enhydris species from Surin Province of Thailand in Table 1. To date, Enhydris subtaeniata has been observed in four countries, Cambodia, Lao PDR, Thailand and Vietnam (Murphy, 2010; Lukoschek et al., 2011; Voris et al., 2012; Uetz et al., 2014). In Cambodia, two specimens were collected from Tonle Sap, Siem Reap Province (Karns et al., 2010; Lukoschek et al., 2011; Voris et al., 2012). In Lao PDR, a series of Enhydris subtaeniata was collected from Dong Khanthung, Champasak Province which lies above the Khone Falls on the southern edge of the Middle Mekong (Lukoschek et al., 2011). The record from Vietnam is based on specimens collected from U. Minh Thong Nature Reserve (Lukoschek et al., 2011). In Thailand, the species was recorded from six provincial areas including Khon Kaen, Nakhon Figure 3. Dorsal (A), ventral (B), and lateral (C) views of Ratchasima, Nakhon Sawan, Prachin Buri, Udon Thani, the head of Enhydris subtaeniata (KKUC 01153) from Baan and Songkhla (Karns et al., 2005; Murphy, 2007; Cox Aayong, Taen Subdistrict, Srikhoraphum District, Surin et al., 2012; Voris et al., 2012). Among these Thai Province, Thailand. Photographs not to scale. Enhydris subtaeniata Table 1. Morphological characteristics of the currently recognized species of Enhydris and of the newly collected specimen from Surin Province of Thailand assigned to Enhydris subtaeniata. Information sources: 1=Murphy and Voris (2005), 2=Cox et al. (2012), 3=Pongcharoen et al. (2015), 4=Karns et al. (2010), 5=Murphy (2007). Countries abbreviation: CN=China, ID=Indonesia, BD=Bangladesh, KH=Cambodia, IN=India, LA=Lao PDR, MY=Malaysia, MM=Myanmar, NP=Nepal, PK=Pakistan, SG=Singapore (?), LK=Sri Lanka, TH=Thailand, VN=Vietnam. Table 1. Characteristics E. chanardi E. enhydris E. innominata E. jagorii E. longicauda E. subtaeniata E. subtaeniata KKUC 01153 SVL in males (mm) na 354-693 up to 390 340-530 na 468-557 - : Newdistributionrecordandmap SVL in females (mm) na 350-788 na 340-650 na 436-688 537 TaiL in males (mm) na na na 95-180 na na - TaiL in females (mm) na na na 100-161 na na 92.1 Dorsal scale rows on neck 20-23 21-27 23-25 23-25 23-26 23-24 21 Dorsal scale rows on mid-body 21 21-23 21 21-23 21 21 21 Dorsal scale rows post-body 19-21 19-21 19-21 19-20 19-21 19-21 19 Dorsal scale ornamentation smooth striated smooth smooth smooth smooth smooth Ventrals in males 110-121 153-174 108-117 117-127 124-133 - 134-153 Ventrals in females 116-122 153-170 111-116 117-120 124-135 143 Subcaudals in males 44-60 64-83 49-56 53-68 64-73 - 46-69 Subcaudals in females 38-49 57-76 42-49 50-54 53-76 46 Number of pairs of chin shields 2 2 (3 rarely) 2 2 2 2 or 3 2 Shape of anterior chin shields flared elongate flared flared flared flared flared Longest pair of chin shields 2 2 1 1 1 1 equal Labials touching loreal first 3 first 3 first 3 first 3 first 3 first 3 first 3 Pattern on scale rows 1-3 stripe stripe blotched blotched blotched stripe stripe Pattern on scale rows 5-7 spots, stripe or uniform blotches, blotches, blotches, spots, spots, 2-3 scales 4-5 scales 4-5 scales 4-5 scales 4-6 scales 4-6 scales Pattern on edges of ventrals zig-zag stripe solid or serrated uniform uniform uniform, zig-zag stripe zig-zag stripe some spots Mid-ventral pattern posterior uniform stripe uniform uniform uniform uniform uniform Distribution TH CN, ID, BD, KH, IN, VN TH KH KH, LA, TH, TH (Surin) LA, MY, MM, NP, PK, VN SG (?), LK, TH, VN 563 Sources of information 1 1,4 1,5 1,3 1 2,5 This study 564 Yodchaiy Chuaynkern et al. focused on the protected areas such as national parks or snake (Enhydris subtaeniata): the biogeographic importance wildlife sanctuaries (e.g., Stuart and Chuaynkern, 2007; of dynamic river drainages and fluctuating sea levels for Chuaynkern et al., 2015). However, the members of the semiaquatic taxa in Indochina. Ecology and Evolution 1(3): 330–342. mud snakes (Homalopsidae) mainly inhabit wetland Murphy, J.C. (2007): Homalopsid Snakes: Evolution in the Mud. reservoirs which are distributed in agricultural areas. Krieger Publishing, Malabar. 249 pp. The Mekong mud snake Enhydris subtaeniata was Murphy, J.C. (2010): Enhydris subtaeniata. The IUCN Red List of never reported from protected areas of northeastern Threatened Species 2010: e.T176693A7284968. http://dx.doi. Thailand. Although several works paid attention to the org/10.2305/IUCN.UK.2010-4.RLTS.T176693A7284968. en. wetland and agricultural areas of northeastern Thailand Accessed on 11 December 2016. (Karns et al., 2005; Voris et al., 2012), the knowledge Murphy, J.C., Voris, H.K. (2005): A new Thai Enhydris (Serpentes: Colubridae: Homalopsinae). The Raffles Bulletin of Zoology is probably still incomplete. Therefore, undiscovered 53(1): 143–147. populations of the mud snakes may exist in northeastern Murphy, J.C., Voris, H.K. (2014): A checklist and key to the Thailand and are waiting for intensive surveys to be homalopsid snakes (Reptilia, Squamata, Serpentes), with the discovered. description of new genera. Fieldiana: Life and Earth Sciences 8: 1–43. Acknowledgements. The authors would like thank our Nabhitabhata, J., Chan–ard, T. (2005) Thailand Red Data: Mammals, institutions for facilitating this work: Khon Kaen University Reptiles and Amphibians.