Larger on average than Melobasis gratiosissima and with head and pronotum differently coloured to elytra, often blue, sometimes green or gold (golden-green in protologue), and with more extensive dark fasciae on the elytra.

Closely related to Melobasis gratiosissima (q.v.) and placed as a synonym under that species by Carter 1909. Emerges earlier than M. gratiosissma and is generally collected in spring (rather than summer like M. gratiosissima).

The taxonomic status of M. speciosa needs further investigation, as M. gratiosissma and M. speciosa are highly variable in size and colouration patterns. This is illustrated by the fact that Obenberger 1942 described three new varieties of M. gratiosissima, all from the same location, interpreted to be Gawler, SA (although given as 'New South Wales: Gowlerstown (Odewahn)').

Blackburn described the underside of M. speciosa as blue, but Obenberger's key gives it as green or green-gold, and has typical M. gratiosissima keyed in a group of varieties that are very blue underneath.