The hennigi-mystery: How an Indian Tiger Beetle species finally found its genus after more than one century
Currently I am working on a revision of the Southeast Asian Tiger Beetle genus Heptodonta (the “Seven-tooth” Tiger Beetles). Hence, I study all described species of this genus and examine if all these taxa are actually valid species or if there are even more undescribed taxa.
One reason why I study this genus is that there is a large mystery amongst the described Heptodonta species: Heptodonta hennigi! Why? Because this species changed its genus names very curiously since it was described in the year 1898. When Walter Horn described this species he was so confused that he actually didn’t want to give it a particular genus name. Therefore, he decided to call this species ‘Heptodonta (or Euryoda?) hennigi’. The reason for that very unconventional nomenclature was that the specimen resembled two very different species from his collection: Heptodonta tricondyloides, now called Dilatotarsa tricondyloides, and Euryoda lucidicollis, nowadays known under the name Prothyma lucidicollis.
However, this name had just a very short lifespan: in the year 1910 Horn changed his mind and called the species Prothyma hennigi. But not only that, he classified the species to a specific ‘genus-group’, called Physodeutera, which can only be found on Madagascar. Then 80 years passed by and no one really cared about Prothyma hennigi, as no further specimens were collected. But then, Jürgen Wiesner noticed, in the year 1992, that Prothyma lucidicollis, the species which was the basis for the classification of hennigi in Prothyma, actually belongs to the Philippine subgenus Symplecthyma. And so Prothyma hennigi moved from Madagascar to the Philippines.
But also Jürgen Wiesner was confused by this classification, and so he labeled his assignment with a question mark. In 2002, also the Italian entomologist Fabio Cassola was confused by this whole situation, and so he remarked that hennigi could also resemble the genus Pronyssa, which was revised by Sawada and Wiesner in 1999. Just one year later, Karl ‘Charly’ Werner had a look at the specimen and labeled it as Pronyssa! While he informed some colleagues about his findings, he did not have the chance to publish his results, because he unfortunately died at just 50 years. So now, it was my turn. Obviously, this specimen could not be Heptodonta, because this genus has no white spots on the elytra; also the head and pronotum were completely different to those of Prothyma. So actually, the classification to Pronyssa was right.
Hence, I redescribed the specimen to present this mysterious species to the scientific world. So finally, this species found its right place in the system of Tiger Beetles. And at the end I also have to say: even for a Pronyssa this species still looks very strange!
Fun fact: Willi Hennig, the founder of phylogenetic systematics and probably the most important person that ever worked at the Museum of Natural History Stuttgart …was not the person to which Horn dedicated the species. Because Pronyssa hennigi was dedicated to the post master department senior secretary Hennig.