Friday, May 16, 2008

WILL THE REAL HEMISCYLLIUM FREYCINETI PLEASE STAND UP?

This is the REAL Hemiscyllium freycineti (an adult is pictured here).

The juvenile of H. freycineti photographed in the Raja Ampat Islands.

Samaria specimen I collected of new Milne Bay epaulette shark species. All photos by Scott W. Michael

Much has been made in recent years about the “walking sharks,” even though they have been known to science for centuries (shark experts have long referred to the group as epaulette sharks because of the epaulette-like markings above the pectoral fins). But the taxonomy of these sharks has been a bit of a mystery and in a state of flux for the last couple of years. Part of this was due to Max Ammer and his dive operations in West Papua (formerly Irian Jaya), Indonesia (click here for more information). I observed photos of the unusual epaulette shark from this region, which appeared to be undescribed based on a revision of the genus (click here to see post about new epaulette sharks from West Papua). To make a long story a bit shorter, the shark in West Papua that appeared to be undescribed turned out to be Hemiscyllium freycineti. But what about the shark in the revision of the genus (Dingerkus and DeFino 1983) that these researchers refer to as H. freycineti? Thanks to some ichthyological detective work done by Dr. Gerald Allen, it was determined the Dingerkus and DeFino H. freycineti is actually an undescribed species! (That is, D and D screwed-up - it happens to the best of us!)

I have been interested in and collecting information on the Hemiscyllium spp. for decades. After examining the distribution of the various species, I started to wonder if the various species have very limited ranges and if the larger distributions attributed to some species is a function of misidentification, as so many of the Hemiscyllium spp. are so similar (more on this in future blogs). It turns out this may indeed be the case and that the species that” D and D (1983)” called H. freycineti (the undescribed species that is) may be limited in distribution to the Milne Bay Province region of eastern Papua New Guinea.

I visited this region in 2003 and was a guest on the Chertan. This live-aboard boat is owned by one of the most congenial people in the dive industry, Rob van der Loos. The idea of collecting and killing one of these beautiful sharks made me queasy! Having had pet epaulette sharks in the past, I look at them more like dogs than fish! But it had to be done – a specimen needed to be collected. Fortunately for me, the Big Guy upstairs was smiling on me on this trip, as on a dive near Samaria Island I found a half-dead (that’s right HALF DEAD) Hemiscyllium sp. rolling around on the sea floor! I took some photos of the shark, grabbed it and took it back to the boat where it was put on ice. Roger Steene and I were able to convince a dogged customs officer to let us take the shark into Australia and Roger then passed the fish onto Gerry. Unfortunately, the specimen ended up in formalin, which made it impossible to conduct DNA analysis on the animal’s tissue. So, we are currently waiting on Roger to get a small piece of fin from a live specimen when he returns to Papua New Guinea this year.

The video below of a Milne Bay epaulette shark (the undescribed species) was taken by Rob van der Loos off his resort (Tawali Resort) in Milne Bay. You will notice the very distinct honeycomb markings of this beautiful shark. Now look at the specimen I collected off the island of Samaria (above), which is less than 100 km southeast (if you follow the coast) of Rob’s resort. Note the color differences (especially of the epaulette over the pectoral fin)? While color differences may or may not be a valid indices when separating different fish species, it seems to be a fairly reliable character when distinguishing the various epaulette sharks. Could it be there are TWO new species off the coast of Milne Bay Province? It may be that the shark above was a bit younger and had not developed the full adult coloration as of yet? Time, Dr. Allen and some shark DNA should be able to tell us soon!

video
Milne Bay epaulette shark filmed off Tawali Resort by Rob van der Loos. NOTICE how shark uses its muscular paired fins to walk over the sea floor.
Copyright (2008) Scott W. Michael

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