Ptychognathus dajie: A new species of Pom Pom Crab from East and Southeast Asia.

The genus Ptychognathus comprises 32 species of brackish-water Crabs found in estuaries and the lower parts of river systems across the Indo-Western Pacific region. They are known as Pom Pom Crabs in the aquarium industry because of the clusters of fine setae (hairs) on their claws (although they are widely traded as freshwater Crabs rather than brackish-water Crabs). Most species of Ptychognathus have very localised distributions, being found on a single island, estuary, or river system, although one species, Ptychognathus barbatus, is found over an extremely wide area, including Japan, Taiwan, China, the Philippines, Malaysia, Indonesia, and New Caledonia. However, as part of a PhD thesis completed in 2006, carcinologist Ngan Kee Ng, then a graduate student at the National University of Singapore, examined the systematics of Ptychognathus barbatus, concluding that the populations described under this name represented two, rather than a single, species. Ng went on the lead a highly successful research group, specialising in the study of Crabs, for many years, before passing away in 2022, but never formerly published her PhD thesis. This means that all taxonomic nomenclature presented in the thesis is considered unusable under the terms of the International Code of Zoological Nomenclature, even if specialists in the field believe it to be generally correct.

In a paper published in the journal ZooKeys on 27 June 2025, Jhih-Wei Hsu of the Department of Life Science at the National Chung Hsing University, Jose Christopher Mendoza, of the Lee Kong Chian Natural History Museum at the National University of Singapore, and Hsi-Te Shih, also of the Department of Life Science, and of the Global Change Biology Research Center at the National Chung Hsing University, build upon Ngan Kee Ng's work, to formally divide Ptychognathus barbatus into two, and describe a new species.

The new species is named Ptychognathus dajie, where 'dajie' means 'elder sister', a title often used for women in leadership roles in Chinese-speaking countries, in honour of Ngan Kee Ng. A genetic analysis of museum specimens suggests that this species is found in estuaries and tidally-influenced portions of rivers, in Malaysia, Japan, Taiwan, China, Philippines, Indonesia, and Thailand. Surprisingly, Ptychognathus dajie is not particularly closely-related to Ptychognathus barbatus, instead forming a sister species to Ptychognathus guijulugani, a species found on Negros and Mindanao islands in the Philippines, placing it close to the base of the Ptychognathus family tree.

A neighbor-joining tree for species of Ptychognathus, based on the COI gene. Probability values at the nodes represent support values. Only values greater than 50% are shown. Hsu et al. (2025).

Specimens of Ptychognathus dajie have almost square carapaces, slightly wider than they are long, with a glossy upper surface and a concave frontal margin. The lower part of the claw is covered by long, thin setae; claws are larger in males than in females. The largest male specimen found was 20.2 mm wide and 16.8 mm long, the largest female found was 16.8 mm wide and 14.5 mm long. Colour is extremeley variable, and tends to match the substrate upon which the Crabs live.

Ptychognathus dajie. (A), (B) Holotype male (13.2 × 11.6 mm, ZRC 2024.0072); (C), (D) Paratype female (10.6 × 9.2 mm, NCHUZOOL 17356); (E) Male (NCHUZOOL 17341); (F) Male (NCHUZOOL 17343); (G), (H) Males (NCHUZOOL 7342). (A), (C) Dorsal view; (B), (D) Ventral view; (A)–(D) Preserved specimens; (E)–(H) Colour in life. Hsu et al. (2025).

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Eruption on Mount Kanlaon.

Mount Kanlaon, a 2465 m stratovolcano (cone shaped volcano made up of layers of ash and lava) on northern Negros Island in the central Philippines, underwent an explosive eruption at 5.51 am local time on Tuesday 8 April 2025, producing an ash column 4 km high which drifted to the west and southwest, according to a bulletin issued by the Philippine Institute of Volcanology and Seismology. The sound of the eruption was heard about 20 km away, and pyroclastic flows were observed on the southern flanks of the volcano, and debris is reported to have set fire to vegetation close to the summit of the volcano. Ash falls were reported up to 50 km from the eruption.

An ash column over mount Kanlaon on 8 April 2025. Philippine Institute of Volcanology and Seismology.

No injuries have been associated with the eruption, but the Philippine Institute of Volcanology and Seismology has recommended that communities within 6 km of  the volcano evacuate the area, and has placed a ban on aircraft overflying the area.

The geology of the Philippines is complex, with the majority of the islands located on the east of the Sunda Plate. To the east of this lies the Philippine Sea plate, which is being subducted beneath the Sunda Plate (a breakaway part of the Eurasian Plate); further east, in the Mariana Islands, the Pacific Plate is being subducted beneath the Philippine Sea Plate. This is not a smooth process, and the rocks of the tectonic plates frequently stick together before eventually being broken apart by the rising pressure, leading to Earthquakes in the process. Material from the subducting Philippine Plate is heated by the temperature of the Earth's interior, causing lighter minerals to melt and the resultant magma to rise through the overlying Sunda Plate, fuelling the volcanoes of the Philippines.

Subduction beneath the Philippines. Yves Descatoire/Singapore Earth Observatory.

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Two-year-old girl killed by landslide in Catbalogan City on Samar Island, Philippines.

A two-year-old girl has been killed and three other people have been injured after a landslide destroyed a house in the Barangay Basiao area of Catbalogan City on Samar Island, Philippines. The incident happened late in the evening of Sunday 29 December 2024, following several days of rain in the area.  Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall. The three people injured are described as  35-year-old man, a 30-year-old-woman, and a baby girl, who were members of the family living in the house. A neighbouring house was also damaged in the incident.

The remains of a house destroyed by a landslide in Catbalogan City on 29 December 2024. RPN DYKC Cebu.

Residents of nearby homes have been evacuated while the situation is assessed, and local government units are also carrying out assessments, and where necessary further evacuations, in other areas which may be at risk of landslips. Much of the island of Samar is currently suffering froom flooding, associated with the Northern Monsoon.

Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate.

Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.

Southeast Asia has two distinct Monsoon Seasons, with a Northeast Monsoon driven by winds from  the South China Sea during the Southern Hemisphere Summer and a Southwest Monsoon driven by winds from the southern Indian Ocean in the Northern Hemisphere Summer. Such a double Monsoon Season is common close to the equator, where the Sun is highest overhead around the equinoxes and lowest on the horizons around the solstices, making the solstices the coolest part of the year and the equinoxes the hottest.

The winds that drive the Northeast and Southwest Monsoons in Southeast Asia. Mynewshub.

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Pothos deleonii: A new species of Arum from Mindanao Island.

Arums of the genus Pothos are hemiepiphytic vines (Plants which begin life as epiphytes growing upon other plants, but which as they grow stronger become self-supporting) found in tropical and subtropical forests in South China, Southeast Asia, Austrolasia, Oceana, and Madagascar. 

In a paper published in the journal PhytoKeys on 15 October 2024, Maria Melanie Medecilo-Guiang of the Center for Biodiversity Research and Extension in Mindanao and Plant Biology Division at Central Mindanao University, and Derek Cabactulan of Cagayan de Oro City, describe a new species of Pothos from Bukidnon Province on Mindanao Island, Philippines.

The new species was first noted as possibly significant on the basis of its remarkable inflorescence, by conservationist and eye surgeon Miguel De Leon at a Robert S. Kennedy Bird Conservancy site in Bukidnon Province during an ornithological expedition in 2019. A subsequent expedition to the same site in February 2024 collected samples of the plant, from which it has been confirmed to be a new species. This is named Pothos deleonii, in honour of the initial discoverer.

Pothos deleonii. (A) Habit with flowering branch, (B) leaf apex, (C) leaf base, (D) venation pattern, (E) inflorescence, (F( detail of spadix. Medecilo-Guiang & Cabactulan (2024).

Pothos deleonii is a root climbing, fibrous liana, with slender, slightly woody, green stems from which slender leaves arise on petioles (leaf stems) at regular intervals. Roots are found along the stem when the plants are young, but become less common as the Plant matures, and tend to be absent around inflorescence-producing termini. Inflorescences are born singularly on elongated peduncles (flower stalks) which hang 16-18 cm below the stem. These inflorescences are a dark wine red, aging to purplish black, with a spadix (spike with a large number of small flowers) up to 6.9 cm long, surrounded by a spathe (petal-like structure) up to 10 cm long and 5.5 cm wide.

Pothos deleonii was found growing at only two locations, climbing on the  base and trunks of Tree Ferns of the genus Alsophila, in an area of degraded secondary, open-canopy Dipterocarp forest, at altitudes of 1150 and 1270 m above sealevel. Once the vines reach about 4-6 m in height they become independent of their host, able to stand free, either on their own base or supported by the surrounding tree canopy. 

Both known sites are within a 5 km² area in the northern foothills of Mt. Kitanglad. This area is protected, and monitored by the Robert S. Kennedy Bird Conservancy, and not considered to be under any threat. However, on the basis of the low number of specimens discovered, and the limited area within which it is found, Medecilo-Guiang and Cabactulan recommend that Pothos deleonii is classified as Critically Endangered under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species.

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Passage of Typhoon Yagi kills at least 39 people across the Philippines, South China, and Vietnam.

Typhoon Yagi is now known to have killed at least 39 people as it swept across the  Philippines, South China, and Vietnam between 2 and 7 September 2024. The storm was initially detected as a low pressure system to the northwest of Palau by the Japan Meteorological Agency on 30 August 2024. By 1 September it has moved to the northeast, gaining in strength to become a tropical depression as it entered the Philippine Area of Responsibility (an area of the northwest Pacific monitored by the Philippine Atmospheric, Geophysical and Astronomical Services Administration. The system was identified as Tropical Depression 12W by the Joint Typhoon Warning Center, and named Enteng by red by the Philippine Atmospheric, Geophysical and Astronomical Services Administration, then as it intensified to become a tropical storm, formally named Tropical Storm Yagi by the Japan Meteorological Agency.

Typhoon Yagi made landfall in Aurora Province on Luzon Island, the Philippines, at about 2.00 pm local time on Monday 2 September, taking fifteen hours to move across the island before emerging over the South China Sea at about 3.00 am on Tuesday 3 September. During this time the storm lost considerable energy, particularly as it passed over the Cordillera Central mountain range, but still causing significant disruption. The storm raised the waters of the Marikana River, which flows through eastern Manila, to rise by 16 m, leading to flooding in the Metro Manila area, as well as in the provinces of Bulacan, Camarines Norte, Camarines Sur, Cavite, Laguna, Northern Samar, Pangasinan, and Rizal. A number of ships were driven aground in Manila Bay, with two colliding and catching fire. Twenty people are currently known to have died as a result of the storm on Luzon, nine of them in Rizal Province, with at least more 26 missing and at least eighteen injured. Around 28 000 people in Metro Manila, Calabarzon, and Bulacan, lost their electricity supplies during the storm, schools were closed for two days, and most flights to and from Luzon Island cancelled. About 80 000 people were evacuated from low-lying areas, with 459 homes destroyed and another 6128 damaged. Several dams had to be opened to prevent them being damaged by high waters, adding to the flooding in areas beneath them.

Flooding in Rizal Province, the Philippines, on 2 September 2024. AP. 

After passing over Luzon Tropical Storm passed across the South China Sea, merging with a smaller depression and gaining significantly in strength as it moved west towards China. By 5 September the storm had gained suficient energy that the Japan Meteorological Agency upgraded it to a Super Typhoon, which is to say a typhoon with windspeeds of 240 km per hour or above, the equivalent to a Category 4 or 5 storm on the Saffir–Simpson scale.

In preparation for this 420 000 people were evacuated from low-lying areas on Hainan Island, and 500 000 from low-lying areas in Guangdong Province, with widespread cancelation of flights, non-essential travel, and coastal activities in both provinces as well as Hong Kong.

Typhoon Yagi made landfall near the city of Wenchang on Hainan at about 4.20 pm local time on Friday 6 September, bringing with it sustained windspeeds of 195 km per hour, making it the strongest storm to hit the island since Typhoon Ramassun in 2014. It passed across the island making, and over the provincial capital, Haikou, before briefly making landfall in Xuwen County, Guangdong Province, then passing out over the Gulf of Tonkin. Four people are reported to have lost their lives on Hainan Island, with another 95 injured, and 1.2 million people losing electricity supplies. Aa further nine people were injured in Hong Kong.

Heavy rainfall and fallen trees in Wenchang City on 6 September 2024. Luo Yunfei/China News Service/VCG/Getty Images.

Typhoon Yaagi gained in strength again as it passed over the Gulf of Tonkin, reaching Vietnam as a Category 4 Typhoon (i.e. a storm with sustained winds in excess of 209 km per hour), making it one of the strongest storms ever to hit northern Vietnam. In preparation for the storm schools were closed and fishing and outdoor gatherings advised against, as well as most flights, ferry services, and sporting events cancelled. The storm made landfall over the city of Haiphong, binging high winds and extensive flooding to the Red River Valley. fifteen people are known to have died in Vietnam, including four people hit by flying debris, another four, described as a family, by a landslide in Hoa Binh, and another man in Hai Dong hit by a falling tree.

High winds caused by Typhoon Yagi on the shore of Phuong Luu Lake in Haiphong. Nhac Nguyen/AFP.

Tropical storms are caused by the warming effect of the Sun over tropical seas. As the air warms it expands, causing a drop in air pressure, and rises, causing air from outside the area to rush in to replace it. If this happens over a sufficiently wide area, then the inrushing winds will be affected by centrifugal forces caused by the Earth's rotation (the Coriolis effect). This means that winds will be deflected clockwise in the northern hemisphere and anti-clockwise in the southern hemisphere, eventually creating a large, rotating Tropical Storm. They have different names in different parts of the world, with those in the northwest Pacific being referred to as typhoons.

The structure of a tropical cyclone. Wikimedia Commons.

Despite the obvious danger of winds of this speed, which can physically blow people, and other large objects, away as well as damaging buildings and uprooting trees, the real danger from these storms comes from the flooding they bring. Each drop millibar drop in air-pressure leads to an approximate 1 cm rise in sea level, with big tropical storms capable of causing a storm surge of several meters. This is always accompanied by heavy rainfall, since warm air over the ocean leads to evaporation of sea water, which is then carried with the storm. These combined often lead to catastrophic flooding in areas hit by tropical storms. 

The formation and impact of a storm surge. eSchoolToday.

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