An Eye-Popping Discovery in Southeast Asian Assassin Bug Biodiversity

Minime_fuliginosa_combined

Physoderes fuliginosa (left), dorsal view; with Physoderes minime (right). Photo by Hwang Wei Song.

Two pop culture characters, Popeye the Sailor and Mini-Me from the Austin Powers comedy movie series, are now linked in eternity in circumstances most unusual – having assassin bugs named after them.

Paraphysoderes popeye and Physoderes minime are two new assassin bug species that were named by LKCNHM Museum Officer Dr. Hwang Wei Song, together with Prof. Christiane Weirauch from the University of California, Riverside, in a recently published European Journal of Taxonomy research article.

The quirky names were given to describe the odd morphology of the bugs — Paraphysoderes popeye has enlarged fore-arms, similar to its namesake, while Physoderes minime looks like a miniature version of a larger known species — Physoderes fuliginosa.

“These names popped up naturally as perfect descriptors of how they look,” said Dr. Hwang, the lead author of the paper.

These two pop-culturally referenced names are among the 15 new assassin bug species named in the monographic piece of work published last week. Not only did the paper reveal the species richness found in the eastern hemisphere, spanning from Madagascar to the Fiji Islands, it also introduced a revised classification of these assassin bugs that more accurately reflects the rich diversity.

Paraphysoderes popeye UCR_ENT 52315 m BPBH dorsal

Paraphysoderes popeye, dorsal view. Photo by Hwang Wei Song.

Decade-long Quest

The task of clarifying and sorting out the taxonomy of this group of tiny, “rather unassuming-looking” assassin bugs known as physoderines, has been a long and arduous journey, starting 10 years ago in 2007, when Dr. Hwang began his PhD studies.

It required the consolidation of over 900 assassin bug specimens from various natural history museums across the world for side-by-side comparisons, visiting museums to check on type specimens, and a detailed computational analysis of their characteristics to determine their evolutionary relationships.

The fact that all 15 new species were discovered from specimens in natural history museum collections highlights the value and relevance of such historical collections to better understand our natural environment.

“These physoderine assassin bugs are miniscule, no bigger than a fingernail, well camouflaged in their natural habitat among vegetation and rotting logs, and extremely difficult to find in the wild,” said Dr. Hwang.

“It would have required my entire lifetime, and probably more, to be able to amass the same number of individuals to study, across such varied landscapes, from the foothills of the Western Ghats in India, across the whole of Southeast Asia, to the tip of Papua New Guinea and beyond.”

Dr. Hwang credits the strong support extended to him by the natural history museum curators and the helpful information shared among assassin bug researchers worldwide in helping to solve the many “taxonomic mysteries and riddles” peppered within this group.

Previously, Madagascar was regarded as an exceptional place for physoderine assassin bugs as they have radiated on the island similar to how lemur diversity flourished there, while the rest of the eastern hemisphere was regarded as rather uneventful. The new study shows that much of the diversity in Southeast Asia is still awaiting discovery, with Borneo and Papua New Guinea islands being hotspots for more species yet known.

To wrap the story up, Dr. Hwang did finally get to come face to face with a live physoderine assassin bug when he encountered Physoderes minime during field work in the Philippines late last year, on top of a dormant volcano.

“It was just hanging around on the base of a tree beside the forest trail, on a rather dreary late afternoon,” he said.

But to him, the thrill of the find was indescribable.

“I will never forget that moment.”

Original paper: Hwang, W.S., Weirauch, C. 2017. Uncovering hidden biodiversity: phylogeny and taxonomy of Physoderinae (Reduviidae, Heteroptera), with emphasis on Physoderes Westwood in the Oriental and Australasian regions. European Journal of Taxonomy 341: 1–118.

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