Tag: Taiwan

Tiny sesame sea slug species discovered in the waters of northern Taiwan

This tiny nudibranch, which measures less than three millimetres in length, was first spotted by lead author Ho-Yeung Chan during a recreational dive in 2019.

Translucent, speckled, and barely the size of a grain of rice, a new species of sea slug has been identified in the coastal waters of Keelung, Taiwan. Because of its minute size and distinctive black and yellow markings, researchers from National Taiwan Ocean University, National Museum of Natural Science and National Taipei University of Education have named the creature Thecacera sesama.

“Taiwanese divers call it ‘sesame’ in Chinese and it is also small like a sesame seed, hence the name,” the research team explained regarding their decision to honour the local nickname in the scientific nomenclature. This tiny nudibranch, which measures less than three millimetres in length, was first spotted by lead author Ho-Yeung Chan during a recreational dive in 2019.

*Thecacera* *sesama* sp. nov. Details of appearance and morphological features, hand-drawn on a tablet PC by Chen-Lu Lee.

The discovery was a stroke of luck that began during Chan’s undergraduate studies:

“During a recreational dive in the summer during the undergraduate study of HY Chan in 2019, he accidentally discovered Thecacera sesama sp. nov. in northern Taiwan waters.”
The Research Team

Despite its unique appearance, the importance of the find was not immediately obvious. In a modern twist on traditional taxonomy, Chan “never realised Thecacera sesama was a new species until he consulted the sea slug expert ‘Hsini Lin teacher’ on Facebook.”

Living specimens of *Thecacera* *sesama* sp. nov. Image credit: Ho-Yeung Chan et al.

Documenting the species proved to be a significant logistical feat due to the volatile environment of the Keelung coast. The research team noted that the most challenging part of the study was the unique weather conditions of the region.

Taiwan experiences frequent typhoons in the summer and large waves during the winter monsoon season, with sea temperatures often dropping below 16 degrees Celsius. These factors mean that diving for nudibranch research is only possible for about four months of the year, making sightings of such tiny creatures entirely a matter of chance.

Living specimens of bryozoan with *Thecacera* species. Image credit: Ho-Yeung Chan et al.

The life of T. sesama is remarkably focused, as the researchers observed that the species exhibits only four primary behaviours: feeding, searching, mating, and laying eggs on bryozoans, which are tiny aquatic invertebrates often called “moss animals”. Interestingly, the specific bryozoan that T. sesama calls home may itself be a species new to science.

From a broader ecological perspective, these vibrant molluscs play a vital role in the marine environment:

“Nudibranchs are one of the key players in the marine food web. They are extremely colourful and can be spotted on coral reef ecosystems. However, many nudibranchs are very small in size and are extremely difficult to spot underwater with the naked eye.”
The Research Team

The researchers believe that the discovery of T. sesama is just the tip of the iceberg for Taiwanese marine biology. Because many species are so small, many more are likely awaiting discovery and formal study. The full research on Thecacera sesama was published in the open-access journal ZooKeys on 11 May 2026.

Original source:

Chan H-Y, Lee C-L, Chen W-C, Chang C-H, Shao Y-T, Pang K-L (2026) Thecacera sesama sp. nov. (Nudibranchia, Polyceridae) from Taiwan, evident from morphology and phylogenetic analyses of the 16S rDNA and cytochrome c oxidase I gene. ZooKeys 1279: 269-284. https://doi.org/10.3897/zookeys.1279.184298

Cover image:

Two individuals of Thecacera sesama sp. nov. feeding on a bryozoan. Image credit: Ho-Yeung Chan et al.

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Is It a Snake or a Lizard? Understanding the Formosan Legless Lizard

These lizards are among the most secretive and least studied groups in Taiwan.

A research team from the National Taiwan Normal University has clarified the status of a secretive reptile through a new study published in the open-access journal ZooKeys. Led by Si-Min Lin, the team focused on the Formosan legless lizard, scientifically known as Dopasia formosensis. These lizards are among the most secretive and least studied groups in Taiwan, living primarily under leaf litter and humus in moist forests. This elusive behavior makes field observations and ecological studies extremely difficult.

The study resolves a century of taxonomic debate over whether Taiwan’s legless lizards comprise one species or two. For decades, these populations were classified as Dopasia harti, a status complicated by the loss of the original Dopasia formosensis type specimen after World War II. To stabilise the identity of the species and re-establish it as the distinct lineage Dopasia formosensis, the research team has designated a “neotype” – this is a new physical specimen that serves as the official reference for the species name.

*Dopasia* *formosensis* in natural habitat: A fully mature adult male showing its dorsal bluish marking; A relatively younger male; A young individual with pale brown dorsal coloration and sharply contrasting black ventral surface. (Photo credit: Yu-Jhen Liang).

Physical Characteristics

The Formosan legless lizard is a medium-sized reptile that lacks external limbs. Adult males typically have a body length between 175 and 230 millimeters, while females are similar in size. A key feature of this species is its exceptionally long tail, which can be nearly double the length of its body.

People often mistake these lizards for snakes, but they possess several distinct features that set them apart. Unlike snakes, legless lizards have external ear openings, although they are quite small. They also have moveable eyelids, which means they can blink, a trait no snake possesses. Further, these lizards have a prominent lateral fold, which is a longitudinal groove running along each side of the body. This fold allows the skin to expand, which is useful for breathing and when females are carrying eggs.

Head morphology of the neotype of *Dopasia* *formosensis*; an adult male from Mingchi, Yilan County, Taiwan. (Photo credit: Chih-Wei Chen and Chin-Chia Shen).

Etymology and Colouration

The species name formosensis is rooted in the historical name for Taiwan, “Formosa”, derived from the Portuguese phrase Ilha Formosa (“Beautiful Island”). The name combines this geographical reference with the Latin suffix “-ensis”, which indicates the place of origin.

**Top:** Landscape near the type locality of *Dopasia formosensis* in Hinokiyama, currently known as a part of the Fuba Cross-ridge Trail.

**Bottom:** Landscape of the collection site of the neotype near Mingchi, Yilan, Taiwan. (Photo credits: Chung-Wei You and Kai-Xiang Chang).

The study also clarified a major point of ambiguity regarding the species’ color. Previously, lizards with bright blue spots were thought to be a different species than those without them. The research team confirmed that these markings are actually a form of sexual dichromatism – while females and young lizards usually have a plain pale brown or bronze color, fully mature adult males often display these conspicuous blue markings as a form of secondary sexual signalling.

Behavioural Characteristics

Since these legless lizards are so rarely seen, the research team relied on citizen science data from the Taiwan Roadkill Observation Network to gather information. In the wild, these lizards prefer high-humidity environments in mid-elevation forests with dense canopy cover.

Sampling sites of *Dopasia* *formosensis* (Kishida, 1930), D. *harti* (Boulenger, 1899), and D. *hainanensis* (Yang, 1983) available from GenBank.

The researchers also noted parental care as a key behavioural characteristic for the species, suggesting that they may exhibit more complex social behaviors than many other reptiles. In related species within the Dopasia genus, for instance, females are known to exhibit egg-guarding behavior, where they remain with their clutch to protect it from predators and environmental hazards until the offspring hatch.

Egg guarding by a female *Dopasia* *formosensis* in the wild, observed in Pingtung County, southern Taiwan. (Photo credit: Weizun Wang).

A prior study documenting the species now recognised as Dopasia formosensis (previously identified as D. harti) notably also detailed its interesting fighting behavior. The encounter begins with a ritualised display where the lizards circle each other with mouths agape, flattened throats, and elevated forebodies. This posturing eventually escalates into physical combat, characterised by one-sided biting and rotational rolling as the males attempt to subdue one another.

Conclusion

The Formosan legless lizard is currently listed as a protected species under Taiwanese law. The research team emphasises that a stable scientific name and clear understanding of the species is critical for future conservation.

“Through these efforts, we aim to provide a more stable framework for future taxonomic, ecological and conservation studies of this overlooked lizard group.”
The Research Team

By making their data openly available, they hope to encourage further study of these unique animals across East Asia.

Original source:

Lin S-M, Shen C-C, Lin T-E, Liang Y-J, Chang W-H (2026) Redescription and neotype designation of Dopasia formosensis (Kishida, 1930) (Squamata, Anguidae) from Taiwan. ZooKeys 1270: 69-98. https://doi.org/10.3897/zookeys.1270.173752

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Over a century later, the mystery of the Alfred Wallace’s butterfly is solved

An over a century-long mystery has been surrounding the Taiwanese butterfly fauna ever since the “father of zoogeography” Alfred Russel Wallace described a new species of butterfly: Lycaena nisa, whose identity was only re-examined in a recent project looking into the butterflies of Taiwan. Based on the original specimens, in addition to newly collected ones, Dr Yu-Feng Hsu of the National Taiwan Normal University resurrected the species name and added two new synonyms to it.

Described by the “father of zoogeography” and co-author of the theories of evolution and natural selection, the species hasn’t been reexamined since 1866

An over a century-long mystery has been surrounding the Taiwanese butterfly fauna ever since the “father of zoogeography” Alfred Russel Wallace, in collaboration with Frederic Moore, authored a landmark paper in 1866: the first to study the lepidopterans of the island.

Back then, in their study, Moore dealt with the moths portion and Wallace investigated the butterflies. Together, they reported 139 species, comprising 93 nocturnal 46 diurnal species, respectively. Of the latter, five species were described as new to science. Even though the correct placements of four out of those five butterflies in question have been verified a number of times since 1886, one of those butterflies: Lycaena nisa, would never be re-examined until very recently.

In a modern-day research project on Taiwanese butterflies, scientists retrieved the original type specimen from the Wallace collection at The History Museum of London, UK. Having also examined historical specimens housed at the Taiwan Agricultural Research Institute, in addition to newly collected butterflies from Australia and Hong Kong, Dr Yu-Feng Hsu of the National Taiwan Normal University finally resolved the identity of the mysterious Alfred Wallace’s butterfly: it is now going by the name Famegana nisa (comb. nov.), while two other species names (Lycaena alsulus and Zizeeria alsulus eggletoni) were proven to have been coined for the same butterfly after the original description by Wallace. Thereby, the latter two are both synonymised with Famegana nisa.

Type specimen of *Famegana nisa*, collected by Wallace in 1866 (upper side).
Credit: Dr Yu-Feng Hsu (courtesy of NHM)
License: CC-BY 4.0

Despite having made entomologists scratch their heads for over a century, in the wild, the Wallace’s butterfly is good at standing out. As long as one knows what else lives in the open grassy habitats around, of course. Commonly known as ‘Grass Blue’, ‘Small Grass Blue’ or ‘Black-spotted Grass Blue’, the butterfly can be easily distinguished amongst the other local species by its uniformly grayish white undersides of the wings, combined with obscure submarginal bands and a single prominent black spot on the hindwing.

However, the species demonstrates high seasonal variability, meaning that individuals reared in the dry season have a reduced black spot, darker ground colour on wing undersides and more distinct submarginal bands in comparison to specimens from the wet season. This is why Dr Yu-Feng Hsu notes that it’s perhaps unnecessary to split the species into subspecies even though there have been up to four already recognised.

Type specimen of Famegana nisa, collected by Wallace in 1866 (bottom side).
Credit: Dr Yu-Feng Hsu (courtesy of NHM)
License: CC-BY 4.0

***

Alfred Russel Wallace, a British naturalist, explorer, geographer, anthropologist, biologist and illustrator, was a contemporary of Charles Darwin, and also worked on the debates within evolutionary theory, including natural selection. He also authored the famed book Darwinism in 1889, which explained and defended natural selection.

While Darwin and Wallace did exchange ideas, often challenging each other’s conclusions, they worked out the idea of natural selection each on their own. In his part, Wallace insisted that there was indeed a strong reason why a certain species would evolve. Unlike Darwin, Wallace argued that rather than a random natural process, evolution was occurring to maintain a species’ fitness to the specificity of its environment. Wallace was also one of the first prominent scientists to voice concerns about the environmental impact of human activity.

***

Original source:

Hsu Y-F (2020) The identity of Alfred Wallace’s mysterious butterfly taxon Lycaena nisa solved: Famegana nisa comb. nov., a senior synonym of F. alsulus (Lepidoptera, Lycaenidae, Polyommatinae). ZooKeys 966: 153-162. https://doi.org/10.3897/zookeys.966.51921

Contact:

Dr Yu-Feng Hsu, National Taiwan Normal University
Email: t43018@ntnu.edu.tw

New species of crab with unusual outgrowths has its name written in the stars

A new species of crab with star-shaped tubercles all over its body has been collected from red coral beds during a survey at a small seamount by Peng-Chia-Yu Island, Taiwan. It has also been found in the Philippines. It is described in the open access journal ZooKeys.

This astonishing creature is distinct with its carapace and chelipeds covered in pointy protrusions. Interestingly, these change with age, becoming shorter, blunter and mushroom-shaped to resemble wart-like outgrowths and granules. Regardless of their sex, as the crabs grow larger, their carapaces also get proportionately rounder and wider.

The curious protuberances on the bodies reminded the research team of Dr. Peter Ng, National University of Singapore, and Dr. Ming-Shiou Jeng, Biodiversity Research Center, Academia Sinica, Taiwan, of stars. Hence, the crab was given the name Pariphiculus stellatus, where stellatus translates as ‘starry’ from Latin.

The colouration of P. stellatus varies among specimens. While predominantly orange with white patches, their shade could be either dull, pale or intense. The white spots might cover some of the protrusions or extend over most of the body. The underside of the body is dirty white to light brown.

Another rare crab species, Acanthodromia margarita, has been reported for the first time from Taiwan in the same study, having previously been known from the Andaman Sea in the eastern Indian Ocean, Japan and the Philippines. The collected female specimen is one of the largest representatives of the species known so far.

“With their bright orange to pink bodies, these hedgehog-like crabs are truly striking in life!” says Dr. Peter Ng.

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Original source:

Ng PKL, Jeng M-S (2017) Notes on two crabs (Crustacea, Brachyura, Dynomenidae and Iphiculidae) collected from red coral beds in northern Taiwan, including a new species of Pariphiculus Alcock, 1896. ZooKeys 694: 135-156. https://doi.org/10.3897/zookeys.694.14871