Of description, drawings and DNA


Dr Arthur Anker examines a shrimp collected from Ningaloo Reef.
Image: Gary Cranitch.

 

25 May 2010
 
 
Tracking the identity of a species is a tricky business, especially when the populations you need to study are located in all four corners of the globe.
 
 
 
Dr Arthur Anker of the Florida Museum of Natural History is interested in the palaemonid shrimp genus Philarius that may help him understand species distribution and diversity in this shrimp group associated with the coral genus Acropora. Two possibly undescribed species were collected on a CReefs trip to Heron Island in 2009.
 
One of the three presently known species, Philarius gerlachei, was originally described, very briefly, in the early 1900s based on specimens from the Persian Gulf. Dr Anker has specimens of Philarius from a Biotas expedition to Madagascar, a Biocode expedition to Moorea in French Polynesia, and the CReefs expedition to Heron Island on the Great Barrier Reef. These specimens share many characteristics with the Persian Gulf specimens, but are different enough, he and his co-author believe, to be classified as separate species.
 
"The specimen from Heron Island is much bigger than the others and more red in colour, the specimen from Madagascar has white spots, and the specimen from Moorea is greenish and semi-transparent – but these different types have all been all treated in the past as the same species, Philarius gerlachei," Dr Anker says.
 
He says it will be necessary to compare these recently collected specimens with the type series from the Persian Gulf – the specimen from which Philarius gerlachei was first described – which is deposited in the National Natural History Museum in Paris. The specimen from French Polynesia may well be the species originally described as Philarius gerlachei.
 
"Once we fix the original species, then we can describe all the others as new," he explains.
 
 
 
"Some descriptions from the 19th or early 20th centuries were taxonomically not adequate, which means today they match several closely related species and we are left to guess what the author meant," Dr Anker says.
 
Descriptive and revisionary taxonomy is quite often necessary, Dr Anker says, to describe new species or to revise previously described species. He hopes that his and his colleagues' work will greatly assist future identification of shrimp species.
 
"After we revise old species and describe new species, it will be much easier for other scientists to contrast their specimens with our descriptions, which contain not only morphological descriptions, but also detailed drawings, colour photographs, keys, and sometimes also DNA sequence data," he says.
 
"Now they will not have to guess: they will know."