Diploderma swinhonis

Diploderma swinhonis
	A Diploderma swinhonis lizard in Taroko Canyon, Taiwan
Conservation status
	; Least Concern (IUCN 3.1)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Iguania
Family:	Agamidae
Genus:	Diploderma
Species:	D. swinhonis
Binomial name
	Diploderma swinhonis; (Günther, 1864)
Synonyms
	Japalura swinhonis ; Günther, 1864; Japalura swinhoei ; Boettger, 1885 ; (nomen substitutum); Japalura mitsukurii ; Stejneger, 1898; Japalura yunnanensis popei ; Wettstein, 1938; Diploderma swinhonis ; — K. Wang et al., 2018;

Diploderma swinhonis, also known commonly as the Taiwan japalure,^[2] Swinhoe's japalure, Swinhoe's lizard, and Swinhoe's tree lizard (Chinese: 斯文豪氏攀木蜥蜴), is a species of lizard in the family Agamidae. The species is native to Taiwan.^[2]^[3]^[4]. It is considered an invasive alien species in Japan after likely being transported from Taiwan by humans^[5]. A foraging ambush predator, this lizard primarily preys on arthropods and remains at the bottom of forests perched on trees where sunlight is present. Diploderma swinhonis is not a major threat to humans and is able to adapt to a variety of habitats, including urban environments. Male Diploderma swinhonis are physically distinct from females, with their body sizes being much larger and having a yellow stripe. These lizards also sexually reproduce on a seasonal basis and hibernate during the winter time.

Etymology

Both the specific name, swinhonis, and some of the common names are in honour of English naturalist Robert Swinhoe.^[6] In Latin, its genus can be broken down into Diplo-, which means many, and derma, which means skin, and it is also referred to by the name Japalura, which is an outdated common name used to previously identify lizards of this genus.^[7]. The common name Japalure is derived from Japalura.

Description

D. swinhonis exhibit sexual dimorphism, with regard to both coloration and size^[8]. The maximum length, including its tail, of D. swinhonis is approximately 31 cm (12 in), it’s body is 8 cm (3.1 in) long^[9]. The average body mass of immature lizards is approximately 2 g while the average body mass of mature lizards is approximately 13.4 g^[5]. The male is also known to be significantly larger than the female, with the snout vent lengths for adult males and females being approximately 73 mm and 62 mm respectively^[5]. Males also have much larger dewlaps than females^[8]. Additionally, they have brown backs, males have a brighter color, and males have a yellow stripe on each side of the body^[3]. Some of the female lizards have a brown-red pattern on the dorsal side of their body^[8]. Males bodies are compressed while female bodies are more cylindrical-like ^[10]. In comparison to other lizards of the same genus, D. Swinhonis is unique in that it has scales that are enlarged and occur irregularly across the dorsal side of the lizard^[10]. Also, these tree lizards have relatively long limbs compared to other lizards, but females have shorter limbs, heads, and tails in comparison to the males^[10]. It is also important to note that there have been physical differences found amongst D. swinhonis based on the region of Taiwan or Japan they are located in, with differences including their weight, sizes, reproductive abilities and period ^[8]. Therefore, these lizards do not necessarily have one unique appearance in the environment.

Geographic range

D. swinhonis is native to Taiwan, where it is found on the islands of Taiwan, Orchid Island, Green Island, and Xiaoliuqiu.^[3] The species has been found in Japan, possibly carried there by humans.^[11]

Behaviour and habitat

D. swinhonis is arboreal and lives at low altitudes below 1,500 m (4,900 ft) in lowland forests within Taiwan.^[12]. The lizard is also diurnal and is commonly found in wide-ranging habitats that include forests and urban areas, such as shopping malls ^[13]. This indicates that the lizard is able to adapt quite well to various environments. Additionally, it is known to reside close to the ground on tree trunks and forage on the ground ^[13]. Males are typically at greater altitudes on the trees, while females and children reside closer to the ground and near bushes ^[14]. Male D. swinhonis use aggressive displays to maintain their territory, and the lizard is known to be an opportunistic predator that waits and ambushes their prey ^[13]. The males have been found to be territorial to increase chances of mating rather than protecting a food resource ^[14]. Larger male lizards have a competitive edge over smaller male lizards in finding mates and maintaining their territory^[15]. Therefore, there is competition within the species in order to find mates. The advantage of being larger might be why males are currently so much larger than females. Between two and three females are found within each male’s territory, and females primarily dig a nest and guard their eggs, causing them to have comparatively smaller ranges ^[14]. In the presence of another animal, the male expands their throat to display white spots inside their throat and scare the intruder ^[9]. Within Taiwan, these lizards are known to hibernate between the months of November and March ^[5]. They are not commonly found when hibernating, but are found outside of this time. The only predator currently found to prey on D. swinhonis is the brown shrike, but only during its migration season ^[14]. With regard to the territories that the male D. swinhonis reside within and defend, they are established once the male is large enough ^[14]). Additionally, males stay within the range that defines their home territory for when they are reproducing and also when they are not reproducing ^[14]. Females on the other hand can leave these ranges after the reproductive season is over, which occurs likely to increase reproductive success with other mates ^[14].

File:Diploderma Swinhonis climbing lizard.jpg

Diploderma Swinhonis climbing a tree

Conservation Status

Over 15 years ago, there was the discovery of Swinhoe’s tree lizard in Japan, which was unprecedented at the time, and the population of these lizards in Japan have since grown^[5]. It is now considered an invasive species there, and action might be taken in the future to remove them. This is because as an invasive species they could be harming the other lizards or reptiles within Japan by competing for the same resources.

Taxonomy/Phylogeny

There are issues with the history of taxonomic classification for Swinhoe’s tree lizard. For one, Japalura swinhonis formosensis, which used to be thought of as a subspecies to Swinhoe’s tree lizard, and Japalura swinhonis mitsukurii are thought to be synonyms to D. swinhonis^[8]. Also, as mentioned before, Jalapura was also used to describe the genus and now further classification has most people using the name D. swinhonis.

Diet

D. swinhonis is known to be a sit-and-wait predator that primarily feeds on mobile and clearly visible prey by ambushing them^[13]. This foraging behavior of ambushing prey is quite common amongst lizards. Swinhoe’s tree lizards feeds on arthropods, primarily ants but also other larger insects such as grasshoppers and crickets^[5]. D. Swinhonis has also been found to feed on bees and spiders, which are also arthropods^[15]. It is also very common for iguanian lizards, like D. Swinhonis, to eat a large proportion of ants within their diet^[15]. Feeding on arthopods active in the daytime, like bees, grasshoppers and ants, is quite common for diurnal species like D. swinhonis while nocturnal arthopods, like crickets, are less commonly eaten^[15]. However, D. swinhonis on Orchid island and found to primarily prey on crickets, so there is some variation with regard to their diets between each of their habitats^[15]. Due to this variation, D. swinhonis is regarded as a dietary generalist^[13].

Reproduction

D. swinhonis is reported to sexually reproduce on a seasonal basis, with females being sexually active between the months of March to August and males being sexually active from March to July^[14]. Spermatogenesis in males occurs around this same time period that females are laying their eggs^[5]. Every year, female D. swinhonis deposit 2 litters of eggs, which include on average 4.27 eggs within every clutch^[9]. Also, eggs within the same clutch have been found to have similarities in terms of their physical dimensions^[8]. D. swinhonis is known to reproduce ovipariously^[9]. The lizard’s reproductive cycle is quite similar to other lizards within Japan and other reptiles living in temperate areas^[5]. It is also known that D. swinhonis female lizards take approximately 350 days to mature while male lizards take between 140 and 260 days to mature depending on whether they are from a late or early clutch^[14]. Therefore, the male lizards take less time to mature in comparison to the females. Also, it has been found that female lizards with snout-vent lengths greater than 50.2 mm are sexually mature ^[5]. Similarly, male lizards with snout-vent lengths greater than 53 mm are also considered mature. These sizes are due to the growth needed for spermatogenesis and the development of ovarian follicles in males and females respectively ^[5].

Life Cycle

Male and female D. swinhonis have a monthly mortality of around 20%, and there is significant mortality prior to maturity^[14]. Specifically, around 88% of eggs do not survive past the initial incubation period of 30 days ^[14]. This high level of mortality means that reproduction does not occur as quickly compared to other species of lizards.There are fluctuations in the population size of male lizards from fighting amongst each other when defending their territories and or competing for mates or resources, but female lizard population size is rather constant since their role does not describe the aforementioned behavior^[14].

Relationship with Humans

Given that Swinhoe’s tree lizard preys on arthropods, it is not an active threat to humans (Huang). However, destruction of its habitat through forces like deforestation might endanger these species in the future.

References

^ Shang G (2019). "Diploderma swinhonis". The IUCN Red List of Threatened Species 2019: e.T103308497A103308500. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T103308497A103308500.en. Downloaded on 28 July 2020.
^ ^a ^b ^c Diploderma swinhonis at the Reptarium.cz Reptile Database. Accessed 19 June 2016.
^ ^a ^b ^c "Diploderma swinhonis (Günther, 1864)". 臺灣生命大百科 (in Chinese). Academia Sinica. Retrieved 2016-05-07.
^ Shao KT (editor). "Diploderma swinhonis (Günther, 1864)". Catalogue of life in Taiwan. Biodiversity Research Center, Academia Sinica, Taiwan. Retrieved 19 June 2016. {{cite web}}: |author= has generic name (help)
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Yasuda, Masahiro (28 August 2020). "Reproductive cycle and maturation of Swinhoe's tree lizard (Diploderma swinhonis (Günther, 1864)) in Hyuga City, Miyazaki Prefecture, Japan". The Journal of Veterinary Medical Science. 82 (10). Retrieved 6 October 2021.
^ Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. ISBN 978-1-4214-0135-5. xiii + 296 pp. (Japalura swinhonis, p. 258).
^ Wang, Kai (January 2019). "Multilocus phylogeny and revised classification for mountain dragons of the genus Japalura s.l. (Reptilia: Agamidae: Draconinae) from Asia". Zoological Journal of the Linnean Society.
^ ^a ^b ^c ^d ^e ^f Norval, Gerrut (19 October 2011). "Notes on the reproduction of the Swinhoe's tree lizard, Japalura swinhonis Günther, 1864, (Squamata: Agamidae) from southwestern Taiwan". Herpetology Notes. Volume 4: 319-324. Retrieved 8 October 2021. {{cite journal}}: |volume= has extra text (help)
^ ^a ^b ^c ^d Qinyuan, Bai. "Diploderma swinhonis (Günther, 1864)". Taiwan Life Encyclopedia. Digital Cultures. Retrieved 8 October 2021.
^ ^a ^b ^c Ota, Hidetoshi (September 1991). "Taxonomic Redefinition of Japalura swinhonis Günther (Agamidae: Squamata), with a Description of a New Subspecies of J. polygonata from Taiwan". Herpetologica. 47 (3): 280-294. Retrieved 8 October 2021.
^ "Japalura swinhonis ". Invasive Species of Japan. National Institute for Environmental Studies, Japan. Retrieved 2016-06-08.
^ Kuo, Chi-Yun; Lin, Yu-Teh; Lin, Yao-Sung (2009). "Sexual Size and Shape Dimorphism in an Agamid Lizard, Japalura swinhonis (Squamata: Lacertilia: Agamidae)" (PDF). Zoological Studies. 48 (3): 351–361. Retrieved 2016-09-11.
^ ^a ^b ^c ^d ^e Norval, Gerrut (2012). "Additional notes on the diet of Japalura swinhonis(Agamidae) from southwestern Taiwan, with comments about its dietary overlap with the sympatric Anolis sagrei(Polychrotidae)". Basic and Applied Herpetology (26): 87-97. Retrieved 8 October 2021.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l Jun-yi, Lin; Kau-hung, Lu (28 May 1982). "Population Ecology of the Lizard Japalura swinhonis formosensis (Sauria: Agamidae) in Taiwan". American Society of Ichthyologists and Herpetologists (ASIH). 1982 (2): 425-434.
^ ^a ^b ^c ^d ^e Huang, wen-san (March 2007). "Ecology and Reproductive Patterns of the Agamid Lizard Japalura swinhonis on an East Asian Island, with Comments on the Small Clutch Sizes of Island Lizards". ZOOLOGICAL SCIENCE. 24 (2): 181-8. Retrieved 8 October 2021.