Complex sentence: The myxoedemae of "Polysphondylium pallidum" were found to exist in two separate mating types in an early (1975) study on the species, but a more recent morphological study left the question of the number of identifiable and separate mating types undecided.
Split into simpler sentences: The myxoedemae of "Polysphondylium pallidum" were found to exist in two separate mating types in an early (1975) study on the species. A more recent morphological study left the question of the number of identifiable and separate mating types undecided.