AmphibiaChina 中国两栖类.

Conservation Status (definitions)

IUCN Red List Status Account Endangered (EN) CITES No CITES Listing National Status None Regional Status None

Description
The Guangxi Diminutive Treefrog, Zhangixalus minimus, has a snout-vent length range of 21.3 – 33.0 mm for males and 31.7 – 38.3 mm for females. The head length is approximately one third that of the snout-vent length. In females the head is a little shorter in length than width, in males the head is as long as it is wide. The snout is rounded in the dorsal view and in the lateral view the snout gently slopes between the eye and the nostril. In females, the snout slopes more abruptly from the nostril to the mandible; in males, the slope is less abrupt and projects beyond the mandible. The protuberant, laterally-directed nostrils are midway between the snout tip and the eye. The distinct canthus rostralis is angular and concave in the dorsal view. The loreal region is concave and slightly oblique. The anterolaterally-directed eyes are large and have pupils that are oriented horizontally. The interorbital region is 140% the length of the upper eyelid length. The tympanum is circular, is distinct, has a raised annulus, and is slightly more than half the diameter of the eye. A curved supratympanic fold is present between the eye and shoulder joint. It does not obscure the dorsal aspect of the tympanum. A linear fold with slightly glandular tubercles is also present, beginning at the corner of the jaw and extends past the end of the supratympanic fold. The body is slender. The dorsal texture is smooth. The ventral surface is areolae, particularly on the abdomen, but less so on the gular and pectoral surfaces. The thigh skin on the posterior and ventral regions below the anal opening is scattered with tubercles. The skin above the vent is slightly elevated (Rao et al. 2006).

The forelimbs are short with slender forearms and large hands. The inner metacarpal tubercle is indistinct, low, and oval. The outer metacarpal tubercle is also indistinct and low, but is distally cleft. The relative length of the basally webbed fingers is 3 > 4 > 2 > 1. The webbing formula is I 2.5 – 2.5 II 2 – 3 III 2.5 – 2.25 IV. The subarticular tubercles are well developed and round. Additional supernumery tubercles can be found on each finger, proximal to the subarticular tubercles closest to the fingertips. The fingertips are rounded, have well-developed discs with oval circummarginal grooves, and have Y-shaped distal phalanges. The hind limbs are short and when adpressed to the body, the tibiotarsal articulation only reaches the posterior half of the eye. The heels do not meet when held at right angles to the body. The foot does not have an outer metatarsal tubercle but the inner metatarsal tubercle is distally raised and oval. The relative length of the webbed toes is 4 > 5 = 3 > 2 > 1. The webbing formula is I 1.5 – 2 II 1.5 – 2.5 III 2 – 2.5 IV 2.5 – 1.5 V. There is one subarticular tubercle on toes 1 and 2 and two on the other toes. The proximal tubercles are smaller than the distal tubercles. There are no supernumerary tubercles. Like the fingers, the toes have oval discs with circummarginal grooves (Rao et al. 2006).

Zhangixalus minimus was initially named Rhacophorus minimus and compared to members of the Polypedates and Rhacophorus genera (Rao et al. 2006), which are members of the subfamily Rhacophorinae. However, since then, members of both genera have been assigned into many other genera (Jiang et al. 2019), but remain in the subfamily. This diagnosis has attempted to take these taxonomic changes into account, but there may still be some name changes that have been overlooked.

The combination of bright green coloration on the dorsum, hand webbing, and foam nests, which is found in Z. minimus, is also found in other members of the Rhacophorinae subfamily. However, Z. minimus is distinguishable from the other green species in the subfamily by having a small snout-vent length and a green dorsal surface that has no pattern and a smooth texture. It has a distinctive white stripe that extends laterally from the snout tip across the upper labial surface to the hip joint. Furthermore, the digits of its forelimbs have less webbing than many other Rhacophorinae species and the tympanum is larger in diameter than the disc on the third finger. More specifically, the small size and slenderness of the body distinguishes Z. minimus from Z. chenfui, Z. hungfuensis, Z. schlegelii, Z. taipeianus, and Z. yaoshanensis. The absence of a brown pattern on the dorsum distinguishes Z. minimus from Z. dugritei. The absence of dark spots on the lateral surfaces of the body distinguishes Z. minimus from Z. dorsoviridis and Z. nigropunctatus. The lack of tubercles on the dorsum distinguishes Z. minimus from Feihyla kajau, Kurixalus appendiculatus, Philautus everetti, Z. chenfui, Z. hungfuensis, and Z. yaoshanensis. The lateral white stripe distinguishes Z. minimus from Z. chenfui, Z. hungfuensis, and Z. yaoshanensis. The lack of any fully webbed digits distinguishes Z. minimus from Leptomantis angulirostris, Rhacophorus bipunctatus, R. edentulus, R. monticola, R. turpes, Z. chenfui, Z. dulitensis, Z. hungfuensis, and Z. yaoshanensis. The tympanum being larger than the disc of the third finger distinguishes Z. minimus from Z. chenfui and Z. hungfuensis. Lastly, the absence of white dots, the presence of a mottled pattern on the lateral surfaces of the body and thighs, brown hands and yellow-green coloration on the digital discs distinguishes Z. minimus from Z. hungfuensis. The snout of Z. yaoshanensis is shaper than that of Z. minimus, and Z. yaoshanensis has red coloration on the thighs (Rao et al. 2006).

In life, Zhangixalus minimus is bright green on its dorsal side with speckling and a white line that extends laterally from the snout tip, across the upper labial surface under the eye, to the hip joint. The hands and feet are mostly light brown with a darker mottled pattern. The finger- and toe-tips are yellow-green. The iris is brown close to the pupil and yellow further away from it, especially on the top quarter of the pupil (Rao et al. 2006).

In preservative, the dorsum is light blue, including midway down the flanks and onto the limbs. Dark blotches are present around the nares, the tympanum, and sparsely across the dorsum. The dorsal surfaces of the hands and feet are olive to light cream and mottled with dark brown. A white line extends from the snout to the hip joint, separating the blue of the dorsum from the ventral coloration. The ventral side of the entire body is cream colored with some dark mottling, especially on the thigh. On the posterior margin of the tarsus and supracloacal fringe is a white ventral line that is bordered with black. The hands and feet are dark on the ventral side (Rao et al. 2006).

Zhangixalus minimus has variation in coloration, skin texture, and displays several sexually dimorphic characters. Nares can vary in the amount of light brown they exhibit. The intensity of the dark brown mottled pattern of the thigh and the lateral white line on the body is variable. Individuals may also have a scattering of asperities on the head or upper eyelid. Females are larger than males. Male heads have a length equal to that of its width (the head is slightly wider than long in female) and the slope of the snout is less steep anterior to the nostrils than that of a female (Rao et al. 2006).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: China

View distribution map in BerkeleyMapper.

Zhangixalus minimus is found in Jinxiu County, Laibin Prefecture, Guangxi Province in the southeast of China. Its range is limited to Dayao Mountain, which is located in the northeastern part of the province (Rao et al. 2006). Its habitat is pristine monsoonal forest and it can be found on grass either in or near shallow ponds. It has been found between 900 m to 1,600 m above sea level (Rao 2008).

Life History, Abundance, Activity, and Special Behaviors
This species is terrestrial (Rao et al. 2006).

Males can be found calling in grass near shallow, freshwater ponds and from perches in broad-leaf trees. The males call mostly during the night but were also heard calling throughout the day. The males use axillary amplexus (Rao et al. 2006).

Zhangixalus minimis is oviparous and builds foam nests, which it attaches to objects outside of the water, to contain protect eggs. The frogs have been observed using artificial water trays for breeding (Rao et al. 2006).

Larva
At stage 35, the total length of tadpoles is 25.5 mm, the body length is 9.2 mm, the body height is 3.8 mm, the body width is 5.9 mm, the maximum tail height is 3.9 mm, the tail muscular height is 2.3 mm. The body is oval shaped, has a lateral constriction when viewed from above, and has a dorso-ventral constriction when viewed laterally. From both the dorsal and lateral views, the snout is rounded. The nostrils are halfway in between the eyes and the snout tip and point antero-laterally. The internarial distance is 1.7 mm. The distance from the eye to the tip of the snout is 3.1 mm. The eyes are located dorsally and have a diameter of 0.9 mm. The interorbital distance is 2.2 mm. The mouth is ventral and 41% of the body width. The oral disc is emarginated. There are two rows of marginal papillae on, but not in between, the anterior and posterior labia. There is a large dorsal gap and a narrow ventral gap. There are no submarginal papillae. The jaw sheath is keratinized, medium-sized, and serrated. The upper jaw has a short lateral process. The labial tooth row formula is 5(2 – 5)/3(1). A single, sinistral spiracle is present at the mid-body and directed postero-dorsally. The vent is dextral. The muscles of the tail taper gradually toward the tip. The tail height is slightly greater than the height of the body and 24% of the tail length. The tail has greatest height at its midpoint, where it’s taller than the body, after which it decreases gradually and is rounded at its tip. The ventral and dorsal fins are somewhat arched and similar in height (Rao et al. 2006).

In life, the tadpoles of Z. minimus are black during the early stages of metamorphosis. As the limbs develop and the tail is reabsorbed, the juvenile become green. In preservative, The dorsum is brownish grey from dense brown chromatophores scattered across the skin. The ventrum is transparent and has fewer chromatophores. The lateral regions of the tadpoles have an intermediate number of chromatophores. The tail musculature is light cream with brown reticulations that extend onto the dorsal fin but not onto the ventral fin (Rao et al. 2006).

Trends and Threats
Zhangixalus minimis is common where it is found, however it is only found in a small (5,000 km²) area and its population is declining. The entire species is limited to five localities and its available habitat is declining due primarily to deforestation for both the logging and farming industries. Because of this, Z. minimus is listed as “Endangered.” It may occur in Dayaoshan Nature Reserve (Rao 2008).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Habitat fragmentation

Comments
Zhangixalus minimus was initially placed in the genus Rhacophorus, based on findings that green dorsum Asian rhacophorids formerly in Polypedates are more closely related to species in Rhacophorus (Rao et al. 2006).

Phylogenetic analyses, using Bayesian Inference, Maximum Likelihood, and Maximum Parsimony methods, on partial fragments of mitochondrial and nuclear genes show that Z. minimus is sister to the clade composed of Z. hungfuensis and Z. wui. The clade composed of those three species is sister to the clade formed by Z. dugritei and Z. hui (Li et al. 2012).

In 2019, Li et al. moved the species to the genus Zhangixalus (Jiang et al. 2019).

References

Jiang, D., K. Jiang, J. Ren, J. Wu, and J. Li (2019). "Resurrection of the genus Leptomantis, with description of a new genus to the family Rhacophoridae (Amphibia: Anura)." Asian Herpetological Research, 10, 1–12.

Li, J.-T., Liu, J., Chen, Y.-Y., Wu, J.-W., Murphy, R.W., Zhao, E.-M., Wang, Y.-Z., Zhang, Y.-P. (2012). ''Molecular phylogeny of treefrogs in the Rhacophorus dugritei species complex (Anura: Rhacophoridae), with descriptions of two new species.'' Zoological Journal of the Linnean Society, 165, 143-162.

Rao D., Wilkinson, J. A. Liu, H. (2006). ''A new species of Rhacophorus (Anura: Rhacophoridae) from Guangxi Province, China.'' Zootaxa, 1258, 17-31.

Rao Ding-Qi. 2008. Rhacophorus minimus. The IUCN Red List of Threatened Species 2008: e.T135910A4219717. http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T135910A4219717.en. Downloaded on 28 April 2018.

Species Account Citation: AmphibiaWeb 2024 Zhangixalus minimus: Guangxi Diminutive Treefrog <https://amphibiaweb.org/species/6779> University of California, Berkeley, CA, USA. Accessed Dec 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Dec 2024.

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