 A 1996 molecular analysis of 38 different Suillus species used the sequences of their internal transcribed spacers to infer phylogenetic relationships and clarify the taxonomy of the genus . The results indicated that S. collinitus is most closely related to a specimen of S. <unk> collected from Nepal . According to the authors , this Nepalese isolate probably represents a species distinct from North American and European isolates , based on morphology and host tree association . In 2006 , a phylogenetic analysis of Suillus isolates collected from Spain showed that S. collinitus was closely related to other species " typical of the Mediterranean area " , namely S. bellinii , S. luteus , and S. mediterraneensis . 
