Didymoglossum radiatum: A new species of creeping Fern from Thailand.

The genus Didymoglossum comprises about 30 species of small, generally tropical Ferns growing as epiphytes (i.e. on other Plants) or epiliths (on rocks). Roughly half of the described species come from the Old World, with eight species from tropical Asia. Five species of Didymoglossum are known from India, five from China, one from Vietnam, four from the Solomon Islands, and six from Malesia (Malaysia, Brunei, the Philippines, and western Indonesia). These Ferns, and possibly other, undescribed species, are likely to also be found in the nations between these documented areas, though as yet few, if any, studies have been carried out in these countries.

In a paper published in the journal PhytoKeys on 6 August 2025, Siwakorn Chokrassameehirun of the Department of Horticulture at Kasetsart University, Ekaphan Kraichak of the Department of Botany and Biodiversity Center at Kasetsart University, and Tassanai Jaruwattanaphan, also of the Department of Horticulture and Biodiversity Center at Kasetsart University, present a study of the genus Didymoglossum in which they describe a new species, as well as documenting other species in the country for the first time.

The new species is described from specimens collected in Hala–Bala Wildlife Sanctuary in Waeng District in the far south of Peninsula Thailand, close to the border with Malaysia. The species is named Didymoglossum radiatum, in reference to the false veinlets on the fronds of the Fern, which form a radiating pattern. 

Didymoglossum radiatum. (A) Habit; (B) Raised sori of fertile Plants; (C) Adaxial surface of sterile fronds; (D) Abaxial surface of sterile fronds; (E) False veinlet construction; (F) Sori. Siwakorn Chokrassameehirun in Chokrassameehirun et al. (2025).

Didymoglossum radiatum can be epiphytic or epilithic in nature, with a long, creeping rhizome 0.2-0.3 mm in diameter firmly anchored to the surface over which it grows by numerous dark brown hairs. It produces plate-like fronds 1.0-1.5 mm in diameter, with dense brown hairs around the rims. Each frond typically bears a single sori (spore-producing body).

Illustration of Didymoglossum radiatum. (A) Fertile frond; (B) Sterile fronds; (C) False veinlet construction; (D)–(E) Sori with tubular involucres; (D) Sori with filiform receptacle; (E) Sori borne at the notch of the frond. Siwakorn Chokrassameehirun in Chokrassameehirun et al. (2025).

Chokrassameehirun et al. also record the presence of two species of Didymoglossum in Thailand for the first time. 

The first of these is Didymoglossum henzaianum, a species which grows on rocks close to streams, which was first described from Myanmar in 2014, and which has subsequently been reported in India, Vietnam, and Peninsula Malaysia. Chokrassameehirun et al. found specimens of this species in Phu Ruea District in Loei Province, in the north of the Country.

Didymoglossum henzaianum. (A) Habit; (B) Fertile plants; (C) False veinlets on lamina segment; (D) Sori with obconic–tubular involucres. Siwakorn Chokrassameehirun in Chokrassameehirun et al. (2025).

The second new report is of Didymoglossum mindorense, a species described in the Philippines in 2006, and subsequently reported from Borneo, New Guinea, the Solomon Islands, and Queensland. Didymoglossum mindorense is found at low elevations, and typically close to streams. It is usually found growing around the bases of trees, but will sometimes colonise rocks. Chokrassameehirun et al. reporr specimens of this species in Hala–Bala Wildlife Sanctuary and the area around it.

Didymoglossum mindorense. (A) Habit; (B) Fertile fronds; (C) Lobe of sterile frond; (D) Fertile frond. Siwakorn Chokrassameehirun in Chokrassameehirun et al. (2025).

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Shark attack injures young surfer in New South Wales.

A young surfer, variously described as 12 or 13, has been injured in a Shark attack off Port Macquarie Beach in New South Wales, Australia, at about 6.00 am local time on Monday 2 November 2020. Despite receiving bite-injuries to his foot, leg, and hand, the victim is described as being in good spirits. He is being treated at Macquarie Base Hospital, where he is described as being in a stable condition. The beach has been closed off temporarily.

 

The beach at Port Macquarie in New South Wales has been temporarily closed off following a Shark attack on 2 November 2020. Kerrin Thomas/ABC News.

Although they have a fearsome reputation, attacks by Sharks are relatively rare. Most attacks on Humans by Sharks are thought to be mistakes, made by species that feed principally on Marine Mammals (which we superficially resemble when we enter the water), gaining the majority of their nutrition from the thick adipose (fat) layers of these animals (which we lack). Due to this, when Sharks do attack Humans these attacks are often broken off without the victim being consumed. Such attacks frequently result in severe injuries, but are seldom immediately fatal, with victims likely to survive if they receive immediate medical attention.

Despite this general rarity, Australia appears to be suffering a sharp rise in Shark attacks, with nine fatal attacks so far this year, the most recent of which occurred near Esperance in Western Australia on Friday 9 October. 

Marine biologist Julian Pepperell has suggested that this increase might be linked to a rise in the number of Humpback Whales, Megaptera novaeangliae, passing through Australian waters each year. Humpback Whales are a significant food source for many Sharks; adult Whales are beyond their hunting capacity, but do die of other causes and are enthusiastically scavenged, while larger Sharks such as Great Wights will attack Whale calves. Around 35 000 Humpback Whales currently migrate through Australian Waters each year, according to  zoologist Vanessa Pirotta of Macquarie University, a number which is growing by about 11% each year.

Humpback Whales were nearly exterminated by commercial Whaling in the first part of the twentieth century. The species has been protected since 1946, and in recent years their population has appeared to be recovering in many areas, now being seen as being of Least Concern  under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species. The Whales are recovering in many parts of the globe, and are starting to appear in areas where they have not previously been recorded.

 

A Humpback Whale, Megaptera novaeangliae, off the East Coast of Australia in July 2017. ABC. 

 

An alternative hypothesis is that the rise in attacks could be linked to a La Niña weather system, which has brought cool water conditions to areas of the central Pacific where the Sharks are usually found, causing them to seek warmer waters closer to the Australian shore, where they encounter, and therefore bite, more Humans.

 

The La Niña weather system is the opposite of the El Niño weather system, in which unusually cold surface temperatures spread across the equatorial Pacific from the upwelling zone on the South American coast. This traps warm water from the western Pacific, preventing it from spreading east and warming the central Pacific. This leads to lower evaporation over the (cooler) east Pacific, leading to low rainfall on the west coast of South America, and higher evaporation over the (warmer) west Pacific, leading to higher rainfall over East and Southeast Asia and northern Australia.

 

The effects of a La Niña weather system in December-February. NOAA.

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