Lau's Leaf-litter Toad
Species Description: Sung Y, Yang J, Wang Y. 2014. A new species of Leptolalax (Anura: Megophryidae) from southern China. Asian Herpetological Research 5: 80-90.
© 2021 Ho Yuen Yeung (1 of 5)
DIAGNOSIS: (How this species is differentiated from similar species)
Leptobrachella laui differs from congeners by a combination of physical traits. 1) They are medium size. The snout-vent length of adult males is 24.8 – 26.7 mm and of a single adult female is 28.1 mm; 2) The species has a completely creamy-white chest and belly, while other species have a stained underside that varies from brown to dark brownish red; 3) Their fingers have broad lateral fringes but congeners have little or no fringes. For example, L. laui has fringes on both sides of the finger II, III and IV, while L. firthi only has wide dermal fringes on finger II; 4) The head of L. laui is longer than or as long as wide, however, congeners all have heads wider than long; 5) L. laui has distant dark brown spots on the flank, of which L. eos lacks; 6) Compared to L. liui that has a grayish-brown dorsum, L. laui has a brown or reddish brown dorsum; 7) The skin of L. laui is scattered with rounded granular tubercles and without glandular folds, while L. liui has glandular folds; 8) L. laui has thin traverse brownish grey bars on the dorsal surface of tibia and lower arms, versus the wider bars in L. liui; 9) The dorsum of L. laui lacks light markings in preservative, which contrasts with the dorsal large dark markings edged with light margins in L. liui; and 10) The longitudinal ridges under toes of L. laui are not interrupted at the articulations, but the ridges are interrupted in L. liui (Sung et al. 2014).
COLORATION: (In life and/or in preservative)
A live specimen has a brown dorsal surface scattered with tiny buff spots, but no distinct darker markings. Faint transverse brownish grey bars are found on the dorsal surface of its fingers, lower arms, tarsus, thigh and tibia. Fingers, toes and elbow to upper arm are pale copper. The ventral surface of chest and belly is opaque creamy-white with little brown dusting along the margins of ventrolateral glands. The throat is transparent pink with brown dusting along the anterior margin. The ventral surface of its arms and thighs is pink with brown dusting along lateral sides, and the ventral surface of tarsus and tibia is brownish pink with creamy white flecks. The axillary, femoral and ventrolateral glands are pale copper. The iris is uniformly coppery orange with fine black reticulations throughout (Sung et al. 2014).
A preserved specimen has a brown dorsal surface and a creamy-white chest and belly. Brown pigments are found on the belly along the edge of the ventrolateral glands. The underside of all limbs is brown (Sung et al. 2014).
Tadpoles are greyish-brown or dark-brown and about 30 mm long. The tip of their tails is round with a transparent tail fin (Programmes of Ecology and Biodiversity 2021).
From the observation of 11 specimens, indistinct darker markings similar to the holotype are common with variation of color between individuals. One of the paratypes collected from Hong Kong has a distinctive darker greyish-brown triangle between the eyes, w-shaped dark marking on shoulder region and scattered large greyish-brown flecks over the iliac region (Sung et al. 2014).
Distribution and Habitat
Leptobrachella laui inhabits rocky, mountain streams in forests located at an elevation of 100 – 800 m (Sung et al. 2014). They prefer streams with moderate to complete canopy cover, regardless of stream width (Karsen et al. 1998).
Life History, Abundance, Activity, and Special Behaviors
Leptobrachella laui is strictly nocturnal and feeds on ants, termites and other small insects. Adults burrow and have adhesion discs on their forelimbs to help climbing on steep surfaces in rocky streams which they inhabit.
The breeding season is from February to September in Hong Kong. During this period, males advertise by making high pitched, cricket-like chirps for territorial defense and attracting females [Listen to frog call in the reference] (Agriculture, Fisheries and Conservation Department 2021). Advertising males can be located at the entrance of burrows or on top of boulders, and within two meters from streams (Karsen et al. 1998, Chan et al. 2005). Females exhibit sex-reversed inguinal amplexus by clasping onto the back of a chosen male, which carries the female to a concealed rock crevice for external fertilization and egg deposition (Sung et al. 2021).
As of 2021, L. laui is the only known species in which the females exhibit sex-reversed inguinal amplexus. All other known amplexus involve the male on top of or in line horizontally (cloacal apposition) with the female. It is postulated that limiting suitable oviposition sites or strong competition for males among females could be evolutionary drivers for the development of this behavior (Sung et al. 2021).
Tadpoles are bottom dwellers and complete metamorphosis in approximately 20 days (Programmes of Ecology and Biodiversity 2021).
Predators include snakes and bigger frogs that also inhabit high-altitude mountain streams and are distributed in similar areas, such as the Asiatic Water Snake (Trimerodytes aequifasciatus), Striped Stream Snake (Opisthotropis) and Lesser Spiny Frog (Quasipaa exilispinosa) (Karsen et al. 1998). When disturbed, an adult is able to expand its body and secrete sticky mucus (Chan et al. 2005).
Trends and Threats
Possible reasons for amphibian decline
General habitat alteration and loss
The genus Leptobrachella is diverse and new species have been frequently described in Asia, up to 86 species (Frost 2021, Wang et al. 2020, Luo et al. 2020, Chen et al. 2019, Wang et al. 2018). There are currently 29 species in China. Phylogenetic studies by Chen et al. (2019) and Luo et al. (2020) yielded similar results from reconstructing a Bayesian tree based on DNA sequences of partial 16S rRNA mitochondrial locus (~530 bp). The results showed that L. laui belongs to the same clade as L. liui, L. mangshanensis, L. maoershanensis and L. yunkaienesis. Another study analyzing 2527 bp sequence of mitochondrial 12S rRNA and 16S rRNA loci inferred that L. laui is the same clade as L. ventripunctatus, L. minimus and L. bourreti (Matsui et al. 2017).
The 29 species of Leptobrachella confirmed in China: L. alpina (Fei, Ye, and Li 1990), L. aspera (Wang, Lyu, Qi, and Wang 2020), L. eos (Ohler et al. 2011), L. feii (Chen, Yuan, and Che 2020), L. flaviglandulosa (Chen, Wang, and Che 2020), L. niveimontis (Chen, Poyarkov, Yuan, and Che 2020), L. pelodytoides (Boulenger 1893), L. purpurus (Yang, Zeng, and Wang 2018), L. tengchongensis (Yang, Wang, Chen, and Rao 2016), L. ventripunctata (Fei, Ye, and Li, 1990) and L. yingjiangensis (Yang, Zeng, and Wang, 2018) from Yunnan; L. bashaensis (Lyu et al. 2020), L. bijie (Wang, Li, Li, Chen, and Wang 2019), L. chishuiensis (Li, Liu, Wei, and Wang 2020), L. dorsospina (Wang, Lyu, Qi, and Wang 2020), L. jinshaensis (Cheng, Shi, Li, Liu, Li, and Wang 2021), L. purpuraventra (Wang, Li, Li, Chen, and Wang 2019) and L. suiyangensis (Luo, Xiao, Gao, and Zhou 2020) from Guizhou; L. yunkaiensis (Wang, Li, Lyu, and Wang 2018) from Guangdong; L. mangshanensis (Hou, Zhang, Hu, Li, Shi, Chen, Mo, and Wang 2018) and L. wulingensis (Qian, Xiao, Cao, Xia, and Yang 2020) from Hunan; L. maoershanensis (Yuan, Sun, Chen, Rowley, and Che 2017), L. shangsiensis (Chen, Liao, Zhou, and Mo 2019), L. sungi (Lathrop, Murphy, Orlov, and Ho 1998) and L. wuhuangmontis (Wang, Yang, Wang 2018) from Guangxi; L. bourreti (Dubois 1983) from Yunnan and Guangxi; L. laui (Sung, Yang, and Wang 2014) from Guangdong and Hong Kong; L. liui (Fei and Ye 1990) from Guizhou, Guangxi, Guangdong, Hunan, Fujian, Jiangxi and Zhejiang; and L. oshanensis (Liu 1950) from Gansu, Sichuan, Chongqing, Guizhou, and Hubei.
ETYMOLOGYThe species was named in honor of Dr. Michael Wai-Neng Lau from Hong Kong for his long-term contribution to herpetological research and conservation in Asia, particularly in South China (Sung et al. 2014).
Agriculture, Fisheries and Conservation Department. (2021, April 23). “Amphibians of Hong Kong.” https://www.afcd.gov.hk/english/conservation/hkbiodiversity/speciesgroup/speciesgroup_amphibians.html#calls Downloaded in April 2021
Chan S.K.F., Cheung K.S., Ho C.Y., Lam F.N., Tang W.S. (2005). A Field Guide to the Amphibians of Hong Kong. Agriculture, Fisheries and Conservation Department, Friends of the Country Parks and Cosmos Books Ltd., Hong Kong.
Chen, J. M., Poyarkov, N. A., Suwannapoom, C., Lathrop, A., Wu, Y-H, Zhou, W-W, Yuan, Z-Y, Jin, J-Q, Chen, H-M, Liu, H-Q, Nguyen, T. Q., Nguyen, S. N., Duong, T. V., Eto, K., Nishikawa, K., Matsui, M., Orlov, N. L., Stuart, B. L., Brown, R. M., Rowley, J. J. L., Murphy, R. W., Wang, Y-Y, Che, J. (2018). "Large-scale phylogenetic analyses provide insights into unrecognized diversity and historical biogeography of Asian leaf-litter frogs, genus Leptolalax (Anura: Megophryidae)." Molecular Phylogenetics and Evolution 124: 162–171. [link]
Chen, W., Liao, X., Zhou, S., Mo, Y. (2019). "A new species of Leptobrachella (Anura: Megophryidae) from southern Guangxi, China." Zootaxa 4563(1): 67–82. [link]
Frost, D. R. (2021). “Leptobrachella Smith, 1925.” In: Amphibian Species of the World: an Online Reference. Version 6.1. Retrieved April 23, 2021, from https://amphibiansoftheworld.amnh.org/index.php. American Museum of Natural History, New York, USA. doi.org/10.5531/db.vz.0001
Hui, T. (2019, March 27). “Leptobrachella laui”. iNaturalist. https://www.inaturalist.org/observations/21658143 Downloaded in April 2021
Karsen, S.J., Lau, W.-N. M., Bogadek, A. (1998). Hong Kong Amphibians and Reptiles. Provisional Urban Council, China.
Lagwan. (2018, April 30). “Leptobrachella laui”. iNaturalist. https://www.inaturalist.org/observations/11767164 Downloaded in April 2021
Luo, T., Xiao, N., Gao, K., Zhou, J. (2020). "A new species of Leptobrachella (Anura, Megophryidae) from Guizhou Province, China." ZooKeys 923: 115–140. [link]
Matsui, M., Eto, K., Nishikawa, K., Hamidy, A., Belabut, D., Ahmad, N.,Panha, S., Khonsue, W., Grismer, L. (2017). "Mitochondrial phylogeny of Leptolalax from Malay Peninsula and Leptobrachella (Anura, Megophryidae)." Current Herpetology 36(1): 11–21. [link]
Pope, C. H. (1931). ''Notes on amphibians from Fukien, Hainan, and other parts of China.'' Bulletin of the American Museum of Natural History, 61, 397-611.
Programmes of Ecology & Biodiversity (2021, April 23). “Images of Amphibians of Hong Kong”. Programmes of Ecology & Biodiversity, University of Hong Kong, Retrieved. https://www.biosch.hku.hk/ecology/hkamphibians/index.htm Downloaded in April 2021
Sung, Y. H., Lee, W. H., Ng, H. N., Crump, M. L., Karraker, N. E. (2021). "Novel reproductive behavior in an Asian frog: sex‐reversed inguinal amplexus." Ecosphere 12(3):e03407. [link]
Sung, Y. H., Yang, J., Wang, Y. (2014). "A new species of Leptolalax (Anura: Megophryidae) from southern China." Asian Herpetological Research 5(2): 80–90. [link]
Wang, J., Lyu, Z. T., Qi, S., Zeng, Z. C., Zhang, W. X., Lu, L.-S., Wang, Y. Y. (2020). "Two new Leptobrachella species (Anura, Megophryidae) from the Yunnan-Guizhou Plateau, southwestern China." ZooKeys 995: 97–125. [link]
Wang, J., Yang, J., Li, Y., Lyu, Z., Zeng, Z., Liu, Z., Ye, Y., Wang, Y. (2018). "Morphology and molecular genetics reveal two new Leptobrachella species in southern China (Anura, Megophryidae)." ZooKeys, 776, 105-137. [link]
Originally submitted by: Amy Fok, Jonathan J. Fong, Yik Hei Sung (2021-05-21)
Description by: Amy Fok, Jonathan J. Fong, Yik Hei Sung (updated 2021-05-21)
Distribution by: Amy Fok, Jonathan J. Fong, Yik Hei Sung (updated 2021-05-21)
Life history by: Amy Fok, Jonathan J. Fong, Yik Hei Sung (updated 2021-05-21)
Trends and threats by: Amy Fok, Jonathan J. Fong, Yik Hei Sung (updated 2021-05-21)
Comments by: Amy Fok, Jonathan J. Fong, Yik Hei Sung (updated 2021-05-21)
Edited by: Ann T. Chang and Michelle S. Koo (2021-05-21)
Species Account Citation: AmphibiaWeb 2021 Leptobrachella laui: Lau's Leaf-litter Toad <https://amphibiaweb.org/species/8201> University of California, Berkeley, CA, USA. Accessed Sep 26, 2021.
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Citation: AmphibiaWeb. 2021. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 26 Sep 2021.
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