Nature notes
The First Record of
Leucism in the Rhabdophis tigrinus (Boie, 1826) (Squamata,
Colubridae) in South Korea
Seung-Min Park1, Seung-Ju Cheon1,
Hye-Rin Park1, Na-Yeong Kim2, Md
Mizanur Rahman3 and Ha-Cheol Sung3*
1Department of Biological Sciences·Biotechnology,
Chonnam National University, Gwangju 61186, South Korea.
2Research Center for Endangered Species, National
Institute of Ecology, Yeongyang 36531, South Korea.
3Department of Biological Sciences, Chonnam National
University, Gwangju 61186, South
Korea.
* Corresponding author.
E-mail address:shcol2002@chonnam.ac.kr
Abstract: Leucism, in which pigmentation is lost over part or the entire
body of an animal, has a range of possible genetic causes. Here, we
report leucism in an individual tiger keelback (Rhabdophis
tigrinus ) found on Jeung Island, Shinan-gun, Jeollanam-do, South Korea,
during a survey of the distribution of reptiles in the area. The
individual was observed sunbathing in the bushes next to a pond. This
individual exhibited ecdysis, thus it considered that have normal
feeding activity. Our report represents the first observation of leucism
in R. tigrinus , and thus, further analysis is needed of this
phenotype to more clearly understand its impact on the species and its
natural history.
Keywords: Tiger keelback; Abnormal color variation; Yellowish snake;
Normal eyes; Ecdysis.
INTRODUCTION
Abnormal color variation on parts or over the entire body of animals has
a variety of genetic causes (Ashaharraza and Lalremsangha, 2020). An
example of this abnormal coloring is leucism, which typically presents
as a partial loss of pigmentation (Lobo and Sreepada, 2016). It appears
similar to albinism, but albino individuals tend to have red eyes due to
a complete lack of pigmentation (Deshmukh et al., 2020), while
individuals with leucism have normal-colored eyes (Acevedo and Aguayo,
2008). Animals with abnormal color variation, such as those with
leucism, can be disadvantaged in nature in various ways to them
(Krecsák, 2008; Bruni, 2017). Because it may encounter an increased risk
of predation (Di Marzio and Rozentāls, 2021), or can lead to potential
problems with thermoregulation and visual acuity (Krecsák, 2008; Bruni,
2017). Therefore, due to low survival rate, individuals with leucism are
difficult to observe in nature (Lobo and Sreepada, 2016).
The tiger keelback (Rhabdophis tigrinus ; Boie, 1826) is a species
of snake found in Russia, Japan (Lee et al., 2011), and throughout South
Korea, including Jeju Island (Jang et al., 2016). This snake is a
venomous snake and has two venom glands, which are used for digestion
and defense (Huthchinson et al., 2007, Lee et al., 2011). The
morphological characteristic of this snake is green with red and black
spots on its neck and keeled on all over the scales (Lee et al., 2011).
Commonly, R. tigrinus is easily found in nearby grasslands,
wetlands, and ponds (Lee et al., 2011). Nevertheless, herein, we report
an individual of R. tigrinus with an abnormal color variation.
Additionally, we build on the research review, collect data on leucism
and albinism found in the species and genus.
MATERIALS AND METHODS
On October 10, 2022, we conducted a survey on the distribution of
reptiles in Jeung Island (Shinan-gun, Jeollanam-do, South Korea; Fig.
1). The region contains agricultural land, beaches, two-lane roads,
rivers, and a small pond. We observed reptile species while walking
slowly across the road. We observed 5 species of reptile:Scincella vandenburghi , Elaphe dione , Oocatochus
rufodorsatus , R. tigrinus , and Hierophis spinalis . We
observed four R. tigrinus individuals (including one that was
dead), but one had an abnormal color. The unusually colored individual
was found near a small pond (34.971606°N, 126.140892°E, elevation 6 m,
Fig. 1). The individual was sunbathing in the bushes next to the pond.
We caught the snake carefully, measured its body and tail length and
after took photos for identification, released it at the same location.
On online searches, we use Google scholar
(www.scholar.google.co.kr)
and use the keywords: Rhabdophis tigrinus , leucism, albinism,
tiger keelback, abnormal color variation, snake, Family Colubridae,
Genus Rhabdophis . Beside English, consider the distribution of
this species, online searches were conducted in Japanese, Chinses,
Russian and Korean.
RESULTS
The observed individual was yellowish overall with no green or black
color (Fig. 2A), its pupils were the same color as those of normal
individuals (Fig. 2B), and it had a pink tongue. Its body length was
39.5 cm, while its tail length was 9.5 cm, for a total of 49 cm.
Especially, we confirmed that the snake was during the process of
ecdysis (Fig. 2B). Based on its body pattern and morphological
characteristic, this abnormal individual was identified as R.
tigrinus , while the characteristics of its abnormal color variation
(i.e., body, eyes, and tongue) suggested that it was leucistic (Lobo and
Sreepada, 2016; Urra et al., 2021). Another normal R. tigrinusindividual observed in the same location was greenish overall, with
black spots across its entire body and a black tongue (Fig. 2C, D).
Online search results were classified only from Southeast Asia and
Middle East Asia. We found total 11 species of snake of leucism and
albinism and location were mostly India (Table 1). However, we no
reports of leucism and albinism with R. tigrinus . On the other
hand, the same genus, we found that albinism of R. rhodomelas and
leucism of R. plumbicolor in Singapore and India.
DISCUSSION
R. tigrinus is very common in South Korea and Japan (Lee et al.,
2011), but reports of leucism have been rare. We searched online to find
reported cases of albino and leucistic R. tigrinus but were
unable to find any. We only found the same genus snakes in albinism and
leucism (R. rhodomelas and R. plumbicolor ). Especially,
most of the albinism and leucism result were from India thus, this
report has a significance as a very rare and important case as Chinese,
Japanese and South Korea. Therefore, this report is the first in all
distribution of this species. In addition, abnormal color individuals
are known to mainly occur in isolated environments (Krecsák, 2008;
Tsuchihashi et al., 2011), so reporting on abnormal individuals to need
to continue for population conservation.
Generally, the size of an adult R. tigrinus is 60−100 cm (Lee et
al., 2011) thus, the observed individual was considered to not yet be
fully mature. In reptiles, feeding and digestion are influenced by body
temperature, and previous studies have suggested that individuals with a
bright body color due to a lack of pigment may have difficulty
regulating this (Kornilios, 2014), with dark colors more efficient in
terms of maintaining the body temperature (Gibon and Falls, 1979). For
this reason, leucistic or albino individuals may experience harmful
consequences for their survival and fitness due to the lack of
thermoregulatory efficiency and camouflage (Krecsák, 2008). However,
this individual seems like leading a normal activity.
Nevertheless, this individual appeared to be engaged in normal feeding
activity because it was undergoing ecdysis (King and Turmo, 1997). As in
this report, about the normal activity of individuals with leucism,
Krecsák (2008) argued that this was possibly due to partially hidden the
body as the trade-off thermoregulation. Furthermore, Bruni (2017)
suggested that they were mainly active around stagnant water with a
temperature higher than the surrounding temperature at night. In fact,
our observed individual was also found near a stagnant pond. However,
the implications of these rare phenotypes for the metabolism,
thermoregulation, and environmental fitness of affected individuals
remain largely unknown (Urra et al., 2021). Therefore, further studies
are needed to understand the impact of these abnormal phenotypes on the
species and their natural history.