Exasperating: elevated blood pressure

Aenictus philippinensis Chapman, 1963

In the case of this ant, it is the circumstances leading to its discovery that were exasperating. Aenictus is a genus of true army ants that are well-known for their unique nomadic lifestyles and military-like precision in raiding nests of their ant prey. James Wittenmyer Chapman was a biology teacher in the Philippines passionate about ant research. Even as enemy soldiers marched on the Philippines, he continued his research.

Chapman discovered Aenictus philippensis while hiding from enemy soldiers on the Horns of Negros at 1,100 metres. He and his wife were later arrested and they spent the rest of the war as POWs. After the war, he would overcome all these difficulties and go on to describe this species in 1963. Aenictus philippensis is only found in ASEAN, in the Philippines.

Labuanium vitatum Ng & Davie, 2011

This species is exasperating because of its ability to out-manoeuvre humans! In addition to being able to climb and live in trees, this species also lives close to the sea in largely inaccessible (for humans) shore habitats. It species name “vitatum” means to “shun” and “frustrating to find” in Latin. A long-time resident on Christmas Island only saw it once in all the years he lived there. Despite the challenges, sufficient specimens have been collected that allowed scientists from Singapore and Australia to name it in 2011. Outside of ASEAN this species is known from Christmas Island (Indian Ocean) and the Andaman Islands in India. Within ASEAN, it is only known from Indonesia (Java and Nias).

Eotrechus fansipan Polhemus, Tran & Polhemus, 2009
Eotrechus vietnamensis Tran & Yang, 2006

Eotrechus fansipan and Eotrechus vietnamensis are two species of water striders or water skaters from Vietnam that have proven to be exasperating. Like Labuanium vitatum above, these two species are exasperating to humans because they are so difficult to study.

Water striders (or water skaters) are known for their ability to skim on the surface of water of ponds, lakes and rivers. Species of the genus Eotrechus have made a unique leap to a whole new type of habitat.

Like other species in the genus, Eotrechus fansipan and Eotrechus vietnamensis live almost vertically around waterfalls. Instead of skating on water surfaces, they cling onto the wet rocky surface of waterfalls and move around by jumping or crawling.

Their body colour often matches well with the surroundings as a form of predator avoidance. Together with the challenge of accessing waterfall habitats, they are often overlooked by field scientists.

Before 2006, only eight species of Eotrechus were known. Since then five more species have been added to the genus. Most species are only found in a very restricted area. Eotrechus fansipan and Eotrechus vietnamensis are only known from Vietnam and are not found outside of ASEAN.

Necroscia affinis (Gray, 1835)
Necroscia confusa (Redtenbacher 1908)

Sometimes it is not just the animals that exasperate scientists. Sometimes scientists exasperate other scientists. Necroscia affinis and Necroscia confusa look superficially similar and their colouration is not entirely helpful in telling them apart. Because of this, the prevailing opinion was that the same species had been named twice by two different scientists. This was a common phenomenon as scientists were sometimes not aware of each other’s work and the origins of the specimens were often confused. Many of these scientists also never ventured beyond their museums and had never seen these animals alive.

It was only in 2017 that the world authority on this group of stick insects determined once and for all that Necroscia affinis and Necroscia confusa are distinct species! Necroscia affinis and Necroscia confusa are only known from the ASEAN region. Necroscia affinisis found in Peninsular Malaysia and Necroscia confusa is found in Singapore.

Roughnose Wedgefish
Rhynchobatus cooki Last, Kyne & Compagno, 2016

The Roughnose Wedgefish was formally named in 2016 but was known to be a distinct species for almost two decades prior. It exasperates scientists because the exact location in which it lives is still unknown. All specimens known to date have been collected in fish markets in Indonesia and Singapore. Boats landing catches in both countries often travel large distances in search of fish, adding to the geographical uncertainty. As fishing in many of these areas continues to be poorly regulated, it is likely that this puzzle will only get more difficult to solve. This species is only known from ASEAN, probably from waters around Indonesia and Singapore.