Now we know! There are OFFICIALLY at least 2 manta species!

Formerly thought to be a single species (Manta birostris), recent research, conducted by Dr Andrea Marshall in Mozambique, showed that there are at least two different species of manta rays (Manta alfredi and Manta birostris). Indeed, after a long wait, the article describing the two species got finally published yesterday (1st December) in a scientific journal (Zootaxa). This is the success after hard work and long wait. Congratulation to Andrea and Mike for publishing this vital piece of information about these mysterious giants.
For your Interest: Marshall AD, Compagno LJV and Bennett MB (2009), Redescription of the genus Manta with resurrection of Manta alfredi (Krefft, 1868) (Chondrichthyes; Myliobatoidei; Mobulidae), Zootaxa, Vol 2301, 1-28pp
Manta alfredi and Manta birostris can be differentiated by few morphological aspects:
The dorsal coloration: M. birostris has very distinctive white triangular shoulder bars while M.alfredi has more faded and rounder coloration mark in this area.
The size: M. birostris can grow up to 8 m while M.alfredi tend to grow up to 5m from one wing tip to the other
Ventral natural markings: M. birostris do not have any spot pattern present between the gill slits and has half moon-shaped markings on both of the last gill slits. M.alfredi can display spot and coloration patterns on most of its ventral surface.
Caudal spine: M. birostris has a vestigial caudal spine, mostly encased in calcified mass and skin, present on the dorsal surface of the tail just behind the dorsal fin. M.alfredi has no sign of this vestigial caudal spine.

So far only the manta species Manta alfredi have been recorded along eastern Australia, yet it doesn’t mean Manta birostris isn’t around.