Hunt for a neotype – first findings!
Article | Updated 1 month ago
In August 2016 the Western Australian Museum asked Geraldton beachcombers, divers, swimmers and anglers to be on the lookout for a very rare marine sponge, Agelas axifera.
This sponge is unique to the Champion Bay area of Geraldton. A holotype was collected in 1905 and sent to Germany for scientific study. Unfortunately that specimen was destroyed during World War II.
Over the past year the WA Museum Aquatic Zoology department, headed by Dr Jane Fromont, have been searching for a new specimen to create a neotype for this species. A holotype is the first example of a named species ever identified, described and published. A neotype is the specimen used when the holotype has been lost or destroyed.
The Western Australian Museum is appreciative of the members of the Geraldton public who submitted sponges that they thought might be the elusive Agelas axifera. Sadly, none of them were, but here is what they did find!
Geraldton Sponge Findings
WA Museum Thorectidae sponges reinforce their skeletons with sand grains and particles that they filter from the sea, and then lay down within their skeleton to give it extra strength.
WA Museum Cymbastela probably stipitata.
WA Museum Cymbastela probably stipitata. This species makes its own spicules by absorbing silicates from the seawater and making them into small glass rods. Cymbastela makes rods that are pointed at both ends called oxeas.
WA Museum Callyspongia species. Callyspongia species also have oxeas but they are smaller than those in Cymbastela.
WA Museum Callyspongia also lays down collagen fibres around the outside of its oxeas.
WA Museum Caulospongia biflabellata. This species has a stalk and always has 2 fan-like lobes, hence its name ‘biflabellata’.
WA Museum Caulospongia biflabellata has collagen fibres cored by a spicule type that is nail-like and called a tylostyle.
WA Museum Tylostyles of Caulospongia biflabellata.
WA Museum Myxillidae sponge.
WA Museum Myxillidae sponges have 3 types of spicules, ones with spines, ones that are smooth and tiny hook-shaped ones called isochelae.
Want to join the search?
“I would encourage everyone in the Geraldton area who explores the beach to look out for a cup-like sponge with a bumpy surface, and possibly a light brown colour," says Dr Fromont.
“The best time to make such a discovery is after a storm or whenever Geraldton has big seas. This is when kelp and sponges are torn off the bottom of the ocean and are washed on to the shore.”
People are asked to first photograph a sponge in situ using their camera or smart-phone so the image records the GPS location of the find. They can then take their discovery to the Museum of Geraldton to be tested.
“Museum staff will perform a bleach test on a small piece of the sponge to determine if it has the characteristic spicules of the Agelas species and, if this is the case, they will preserve the collected specimen in ethanol and arrange for its transport to Perth.”
“Sponges up to 12 months old may still have molecular value so if you think you found something like the Agelas axifera in recent times, and you still have it, you can also bring this to the Museum to be assessed.”
The discovery of a neotype would help the WA Museum identify other sponge specimens in the State Collection, by providing a known example of Agelas axifera for comparison.