Australian Research Team Discovers New Species of Mola Hiding in Plain Sight
After four years of research, a team of Australian scientists has discovered a new species of sunfish, and the newest addition to the family of the world’s largest bony fish was hiding in plain sight.
In 2013, Marianne Nyegaard of Murdoch University, Australia, began her PhD studying the population of sunfish around Bali, Indonesia. As she writes in her blog on the Conversation, little did she realise that she would discover an entirely new species.
There are – or were – three different species of sunfish in the Molidae family, falling into two separate genera. The little known Masturus lanceolatus, also called the sharptail mola for the strangely-shaped spike on its caudal (tail) fin, along with the much more common Mola mola (oceanic sunfish) and Mola ramsayi, the southern mola.
Analysing skin samples taken from fish that had been accidentally caught or stranded, Nyegaard realised that agenetic samples that did not match the DNA of those species were regularly turning up in her samples.
Sunfish are relatively common, but they are very elusive. They frequent cool water, diving as deep as 200m where they feed on jellyfish, rising to shallower depths to make use of cleaning stations, and basking on their sides at the surface to capture the warmth of the sun – hence the name.
'Finding these fish and storing specimens for studies is a logistical nightmare due to their elusive nature and enormous size, so sunfish research is difficult at the best of times,' said Nyegaard in a press release. 'Early on, when I was asked if I would be bringing my own crane to receive a specimen, I knew I was in for a challenging – but awesome – adventure.'
After realising that there was a DNA mismatch, Nyegaard began trawling through the Internet, looking for anything that might differentiate a new species from the thousands of pictures that were available. She named it Mola tecta - the hoodwinker sunfish - from the latin tectus, which means 'hidden'.
The breakthrough came in 2014 when observers from the Australian and New Zealand fisheries department sent her a picture of a complete juvenile sunfish that they were freeing from their lines. Noting a small structure on the rear of the tail fin that she had not seen in other sunfish, Nyegaard 'hit the jackpot' when four fish were stranded simultaneously in New Zealand.
'I flew down to Christchurch, landed at night and drove out on to the beach,' she writes. 'I saw my first hoodwinker sunfish in the headlights of the car – it was incredibly exciting. This changed everything, because now we knew what we were looking for.'
The new species – the first to be added to the genus in 130 years – is similar in size and shape to the Mola mola and Mola ramsayi in that it can grow to around 2.5m from fin-tip to fin-tip and weigh over two tonnes. The most notable differences are the slight separation between the upper and lower lobes of the truncated caudal fin, and the fact that the hoodwinker sunfish remains much sleeker than the other species throughout its lifespan, without the elongated snout and other 'lumps and bumps' that they develop.
So far Mola tecta has been identified in the cooler waters off New Zealand, southern Australia, South Africa and southern Chile.