Complex sentence: Specimens from the northern parts of the species range (alpine form) are generally larger, blacker and tend to have more colourful blotches on their back, which are sometimes pale pink, salmon-pink or orange in colour.
Split into simpler sentences: Specimens from the northern parts of the species range (alpine form) are generally larger and blacker. They also tend to have more colourful blotches on their back, sometimes being pale pink, salmon-pink or bright orange in colour.