Habanero chilli
A small, lantern-shaped chilli from Yucatán, usually orange, very hot and distinctly fruity and floral in aroma.
Fresh habaneros turn up in well-stocked supermarkets, at markets, in Asian or African grocers and by mail order, and dried or powdered from spice shops. The closest relative is the Scotch bonnet, almost identical in heat and fruity aroma.
Substitute:
Scotch bonnets are an almost like-for-like swap; small Thai or bird's eye chillies deliver the heat but not the fruity aroma that defines Yucatán-style salsas.