Morphological and acoustic characteristics of two species of the genus occidozyga kuhn and van hasselt, 1822 (anura: dicroglossidae) in Viet Nam

177 HNUE JOURNAL OF SCIENCE DOI: 10.18173/2354-1059.2018-0087 Natural Sciences 2018, Volume 63, Issue 11, pp. 177-184 This paper is available online at MORPHOLOGICAL AND ACOUSTIC CHARACTERISTICS OF TWO SPECIES OF THE GENUS Occidozyga Kuhn and Van Hasselt, 1822 (ANURA: DICROGLOSSIDAE) IN VIETNAM Le Trung Dung and Luong Mai Anh Faculty of Biology, Hanoi National University of Education Abstract. We describe morphological and acoustic characteristics of two species (Occidozyga lima, O. martensii) in the genus Occidozyga from Van Long Wetland Nature Reserve (Ninh Binh province) and Dong Nai Culture and Nature Reserve (Dong Nai province). Two medium large species with half webbed toes, dorsum uniformly coloured, light dorsolateral stripe; tympanic hidden under skin and completely covered under temporal musculature; vomerine teeth absent, tongue completely rounded, no median notch behind. O. lima difers from O. martensii by having dorsal colors (dark olive with dark spots or fleckes scattered thickly vs. beige grey). This is the first study that describes calls from this genus in Vietnam. Five acoustics parameters were measured, including call duration (s), call repetition rate (calls/s), inter-call interval(s), number of notes or pulses in a call, dominant frequency of call (kHz). Keywords: Occidozyga, morphology, acoustic, Van Long Wetland Nature Reserve, Dong Nai Culture and Nature Reserve. 1. Introduction The genus Occidozyga type species O. lima (Gravenhorst, 1829), comprises 12 species, widely distributed in Southeast Asia, extending to India in the west and China in the north, with endemic species in the Philippines, Sundaland and Wallacea (Frost, 2018) [1]. This is a genus that has raised many controversies, as the generic assignment of several of its members is a source of disagreement among scientists, aside from various orthographical versions (Iskandar et al., 2011) [2]. The genus Occidozyga is one of the most poorly studied genus of amphibians in Vietnam. Currently, only three species of the genus was recorded in this country, including: O. lima, O. martensi, and O. sumatra. Two species O. lima and O. martensi have been recorded wide distribution in Vietnam while the species O. sumatra is currently only found in Central and South Vietnam. Up to now, there have been no acoustic study of these species in Vietnam. Based on newly collected, we herein provide morphology and acoustic characters of two amphibian species with wide distribution in Vietnam: Occidozyga lima (Gravenhorst, 1829), amphibians from Van Long Wetland Nature Reserve (Ninh Binh province) and Occidozyga martensii (Peters, 1867) from Dong Nai Culture and Nature Reserve (Dong Nai province). Received September 6, 2018. Revised November 16, 2018. Accepted November 26, 2018. Contact Le Trung Dung, e-mail address: letrungdung_sp@hnue.edu.vn Le Trung Dung and Luong Mai Anh 178 2. Content 2.1. Materials and methods Sampling: Field surveys (Fig. 1) were conducted July 2015, September 2015 and March 2016 in Van Long Wetland Nature Reserve (Ninh Binh province) and May 2016 in Dong Nai Culture and Nature Reserve by Le Trung Dung and Luong Mai Anh. Specimens were collected between 7:00 and 12:00 pm. After taking photograph specimens were preserved in 80% ethanol and subsequently transferred to 70% ethanol for permanent storage. Specimens were deposited in the Hanoi National University of Education (HNUE). Figure 1. Map showing the survey sites in Vietnam: (1) Van Long Wetland National Reserve, Ninh Bình province and (2) Dong Nai Culture and Nature Reserve, Dong Nai province Morphological characters: Measurements were taken with a digital caliper to the nearest 0.1 mm. Abbreviations are as follows: a.s.l., above sea level; terminology of morphological characters followed Ohler et al. (2011) [3]. The following abbreviations were used: SVL, snout-vent length; EL, eye length, from anterior corner to posterior corner of eye; EN, distance from anterior corner of eye to posterior edge of nostril; HL, head length, from posterior corner of mandible to tip of snout; HW, maximum head width at the angle of jaws; IBE, distance between anterior corners of eyes; IPE, distance between posterior corners of eyes; IN, internarial distance; IUE, minimum distance between upper eyelids; MBE, distance from posterior corner of mandible to posterior corner of eye; MFE, distance from posterior corner of mandible to anterior corner of eye; MN, distance from posterior corner of mandible to posterior edge of nostril; NS, distance from anterior edge of nostril to tip of snout; SL, distance from anterior corner of eye to tip of snout; TYD, maximum tympanum diameter; TYE, distance between Morphological and acoustic characteristics of two species of the genus occidozyga Kuhn and Van Hasselt, 179 anterior margin of tympanum and posterior corner of eye; UEW, maximum width of upper eyelid; FLL, forearm length, from elbow to base of outer palmar tubercle; HAL, hand length, from base of outer palmar tubercle to tip of third finger; TFL, third finger length, from articulation of proximal and intermediate phalange; FL, thigh length, from vent to knee; FOL, foot length, from base of inner metatarsal tubercle to tip of fourth toe; FTL, fourth toe length, from articulation of proximal and intermediate phalange; IMT, length of inner metatarsal tubercle; ITL, inner toe length; TL shank length; TW maximum shank width; a.s.l., above sea level. For webbing formula we followed Glaw &Vences (2007) [4]. Recording methods: Advertisement calls were recorded with a Sony Recorder ICD–UX200F and a Parabolic microphone Telinga Pro–4PIP. Calls were recorded at a distance of approximately 0.2 m and ambient temperatures at the calling site were taken immediately after recording using an electronic thermal hygrometer Nakata NJ–2099–TH. Acoustic analysis: Calls were analyzed by using Raven Pro., version 1.3 (Cornell Laboratory of Ornithology, Ithaca, New York, U.S.A.) at resolution of 16 bit and frequency of 44.1 kHz. Spectrograms were performed with Hann window type, frame length of 1024 samples, and corresponding 3 dB filter bandwidth of 67.4 Hz; frame overlapped 50% with time–grid resolution of 512 samples and frequency– grid resolution of 46.9 Hz. For each acoustic signal, the following parameters were measured: call duration or call length(s): duration of time between beginning and end of a call; call repetition rate (calls/s): (total number of calls−1)/duration of time between beginning of the first call and end of the last call; inter-call interval(s): duration of time between end of the first call and beginning of the second call; number of notes per call: total number of notes in a call; number of pulses per note: total number of pulses within a note (in some cases); dominant frequency of call (kHz): the emphasized harmonic in the spectrum (after Duellman and Trueb, 1994 [5]; Cocroft and Ryan, 1995 [6]). The ten first notes of each call were removed according to research by Pröhl (2003) [7]. We calculated the coefficients of variation (CV=[SD/mean]×100%) of the acoustic features measured in calls. We employed the criteria of Gerhardt (1991) [8] and classified as static those acoustic properties with average within individual CV 12%, and CV from 5-12% was intermediate level of within–individual variation. 2.2. Results and discussions Occidozyga lima (Gravenhorst, 1829) / Green Puddle Frog / Coc nuoc san Specimen examined (n = 11). Ten adult males (HNUE.VL.2015.25, 47, 48, 64-69, 156) and an adult female (HNUE VL.2015.70) collected in July 2016 from Van Long lake, Gia Van Commune, Van Long Wetland Nature Reserve (N 20 0 21.807’ E 1050 52.972’, at an elevation 6 m asl.). Decription. Morphological charecters of the specimens from Ninh Binh Province agreed well with the descriptions of Gravenhorst, 1829 [9]; Taylor, 1962 [10]: Body small (SVL 16.8-23.9 mm in males; SVL 27 mm in the female). Head longer than wide (HL 6.5-9.1 mm, HW 6.4-8.5 mm, HL/HW 1-1.22 in males; HL 9.9 mm, HW 9.3 mm, HL/HW 1.06 in the female); snout rounded, approximately by eye diameter (SL 1.9-2.7 mm, ED 2.2-3 mm, SL/ED 0.83-1.17) in males and longer than eye diameter (SL 3.3 mm, ED 2.5 mm, SL/ED 1.32) in the female; interorbital distance as upper eyelid width (IUE/UEW 0.87-1.55 in males, IUE/UEW 2 in the famale); tympanum indistinct; vomerine teeth absent, tongue long, narrow. Forearm short (FLL 3.6-4.3 mm, FLL/HAL 0.58-0.9 in males; FLL 4.8 mm, FLL/HAL 0.69 in the famale), tips of finger pointed, fingers about one fourth webbed, webbing fomula: I1 2 1 –2II2-2 21 III2–2IV. Hindlimbs short (FL 9.3-12.5 mm, TL 9.2-11.7 mm in males; FL 12.9 mm, TL 13 mm in the female), tips of toes pointed, fully webbed, inner metatarsal tubercles small, oval. Dorsal skin granular, supratypanic fold distinct. Coloration in life: On dorsal surfaces, dark olive with dark spots or fleckes scattered thickly on back, sides, and limbs; snout darker olive; on middel of side Le Trung Dung and Luong Mai Anh 180 an indefinite black line below which is an indefinite greenish cream line; two dark lines begin on breast, extend forward to tip of chin and meet; venter cream with a fine powering of blackish brown. Acoustic properties. The calls emitted by one male (HNUE.VL.2015.64) were recorded at an air temperature of 32.1 o C and a relative humidity of 70%. The calls were composed of multinote, lasting for 2.497 - 3.248 s (2.7948 ± 0.3219 s, n = 6), call repetition rate 0.0657 calls/s (n = 1), intercall interval 9.339 - 24.87 s (14.91 ± 6.0392, n = 5). Each note consisted of multipulse (155 -165 pulse). The dominant frequency of the primary calls from 2.929 to 3.187 kHz (3.101 ± 0.094, n = 6). Variation of acoustic. Rise time of calls (mean CV = 11.52%), inter–call interval (mean CV = 40.5%) and dominant frequency (mean CV=3.03%) were the most stereotyped properties. Calling behavior. Calling males were found standing on the leaves firearms or bushes reed. The smallest distance between two calling males was about 0.5 - 1 m. Females are found on the ground next to the males. Remarks. The specimens from Ninh Binh differ from those in the original description of Taylor (1962) in having a subarticular tubercles indistinct versus subarticular tubercles distinct. Advertisement calls of the specimen agreed well with the description of Tran et al. (2016) [11] in having dominant frequency higher (2.929 - 3.187 kHz versus 2.816 - 3.0 kHz). Figure 2. Occidozyga lima from Van Long Wetland Nature Reserve: (a, Waveform and corresponding spectrogram; b, Dorsolateral view) Occidozyga martensii (Peters, 1867) / Marten’s Oriental Frog / Coc nuoc mac–ten Morphological and acoustic characteristics of two species of the genus occidozyga Kuhn and Van Hasselt, 181 Specimen examined (n = 4). Four adult males (HNUE.DN.2016.43, 46, 48, 56) collected in May 2016, from Hieu Liem Commune, Dong Nai Culture and Nature Reserve (N 11 o 11.237’ E 107 0 03.692’, at an elevation 94 m asl.) Figure 3. Occidozyga martensii Dong Nai Culture and Nature Reserve (a, Waveform and corresponding spectrogram; b, Dorsolateral view) Decription. Morphological charecters of the specimens from Dong Nai Province agreed well with the descriptions of Peters, (1867) [12] and Tran (2013) [13]: Body small (SVL 19.6 - 25.7 mm). Head longer than wide (HL 6.8 - 9.1 mm, HW 6.0 - 8.9 mm, HL/HW 1.4 - 2.3); snout rounded, longer than eye diameter (SL 2.5 - 3.4 mm, ED 2.1 - 3.2 mm, SL/ED 0.9 - 1.21); interorbital distance approximately upper eyelid width (IUE/UEW 0.87 - 1.55); tympanum indistinct; vomerine teeth absent, tongue rounded. Forearm short (FLL 4.0 - 4.8 mm, FLL/HAL 0.8 - 0.82), tips of finger rounded, fingers free webbing. Hindlimbs short (FL 9.9 - 13.0 mm, TL 9.2 - 12.0 mm), tips of toes pointed, webbing fomular: I0-0II0-0III0-1IV1-0V, inner metatarsal tubercles small large. Dorsal skin smooth with gladular, supratypanic fold distinct. Coloration in life. Dorsal beige grey, with a darker stripe between eyes; one light vertical bar from eye to snout; limbs with transverse bars; ventral surface white, gular region marbled with black. Le Trung Dung and Luong Mai Anh 182 Acoustic properties. The calls emitted by one male (HNUE.DN.2015.43) were recorded at an air temperature of 28.2 o C and a relative humidity of 75%. The calls were composed of singernote (44 calls) and multinote (11 calls). Single note (44 calls) lasting for 0.03 - 0.104 s (0.052 ± 0.014 s, n = 44), call repetition rate 0.434 - 1.13 calls/s (n = 3), inter–call interval 0.27–5.461 s (1.973 ± 1.078, n = 41). Each note consisted of multipulse (16 - 26 pulse). The dominant frequency of the primary calls from 3.445 to 3.79 kHz (3.516 ± 0.136, n = 44). Variation of single note. Rise time of calls (mean CV = 28%), inter–call interval (mean CV=54.67%) and dominant frequency (mean CV=3.86%) were the most stereotyped properties. Multinote (11 call) lasting for 0.034–0.088 s (0.048 ± 0.015 s, n = 11), call repetition rate 0.165 - 0.429 calls/s (n = 3), inter–call interval 1.424 - 14.119 s (7.118 ± 4.938, n = 9). Each note consisted of multipulse (18 - 26 pulse). The dominant frequency of the primary calls from 3.445 to 3.79 kHz (3.508 ± 0.139, n = 11). Variation of multinote. Rise time of calls (mean CV = 31.11%), inter-call interval (mean CV=69.37%) and dominant frequency (mean CV = 3.97%) were the most stereotyped properties. Calling behavior. Calling males were found standing on the ground. The smallest distance between two calling males was about 0.2 - 0.5 m. Females are found on the ground next to the males. Variation of morphology and acoustic of the genus Occidozyga in Vietnam Figure 4. Oscillate dominat frequency of three Occidozyga species Occidozyga Kuhl & van Hasselt, 1822 is a small frog breed. At present, there are 12 species that are characterized by very little morphological differences, in which two species Occidozyga lima and O. sumatra have known advertisement call (Tran, 2013; Tran & Dau, 2016) [11, 13]. Vietnam is center of this genus with 3 species (Nguyen et al., 2009) [14], in this study, we collected specimens and acoustic characters of two species of this genus, including O. lima and O. martensi. Two medium large species with half webbed toes, dorsum uniformly coloured, light dorsolateral stripe; tympanic hidden under skin and completely covered under temporal musculature; vomerine teeth absent, tongue completely rounded, no median notch behind. O. lima difers from O. martensii by having dorsal colors (dark olive with dark spots or fleckes scattered thickly vs. beige grey). We found large differences in the calls of different species in features such Morphological and acoustic characteristics of two species of the genus occidozyga Kuhn and Van Hasselt, 183 as call duration, note number, inter-call interval and dominant frequency. In which the dominant frequency of species can be considered static properties. Comparison of vocalisation of two species recorded with previous studies: Occidozyga martensii and Occidozyga sumatra have two type singernote and multinote but mainly singernote with dominant frequency 3.445 - 3.79 kHz other than species Occidozyga lima only multinote with a dominant frequency of 2.929 - 3.187 kHz and higher than O. sumatra 2.594 - 2.877 kHz (Márquez and Eekhout, 2006) in Indonesia [15]. 3. Conclusions Morphological and acoustic characters of two species were first described in Vietnam, Occidozyga lima from Van Long Wetland Nature Reserve (Ninh Binh province) and O. martensii from Dong Nai Culture and Nature Reserve (Dong Nai province). Two medium large species with half webbed toes, dorsum uniformly coloured, light dorsolateral stripe; tympanic hidden under skin and completely covered under temporal musculature; vomerine teeth absent, tongue completely rounded, no median notch behind. O. lima difers from O. martensii by having dorsal colors (dark olive with dark spots or fleckes scattered thickly vs. beige grey). Five acoustics parameters were measured, including call duration (s), call repetition rate (calls/s), inter–call interval(s), number of notes or pulses in a call, dominant frequency of call (kHz). We found large differences in the calls of different species in features such as call duration, note number, inter-call interval and dominant frequency. In which the dominant frequency of species can be considered static properties. An acoustic review of Vietnamese members of the genus Occidozyga showed that the dominant frequency of the calls to be is distinctly different in the species, it could be considered as static properties. Acknowledgements. We are grateful to the directorates Van Long Wetland Nature Reserve and Dong Nai Culture and Nature Reserve for support of our field work and issuing relevant permits. We thank D.T. Pham (Hanoi National University of Education), staff of Van Long Wetland Nature Reserve and Dong Nai Culture and Nature Reserve for their assistance in the field. We thank Y. T. Do and T. S. Nguyen (Hanoi National University of Education) for laboratory assistance, E. Sterling and K. Koy for providing the map. This research was partially funded by the Hanoi National University of Education (Grant No. SPHN16-19TT). REFERENCES [1] Frost, D.R., 2018. Amphibian species of the World: an online reference, Version 6.0, Electronic Database accessible at index.html. American. [2] Iskandar D. T., Arifin U., Rachmansah A., 2011. A new frog (Anura, Dcroglossidae), related to Occidozyga semipalmata Smith, 1927, from the Eastern Penisula of Sulawesl Indonesia. The raffles bulletin of Zoology, 59(2): 219-228. [3] Ohler A., Wollenberg K. C., Grosjean S., Hendrix R., Vences M., Ziegler T., Dubois A., 2011. 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