Boletellus ananas and B. emodensis are undoubtedly two of the most widely encountered, known or recognized taxa of the genus; at least the names are the most commonly used in the literature. The type specimen of emodensis was collected in Sikkim, India and the type of ananas was collected in South Carolina, USA. Both possess reddish pigments, squamose-scaly pilei, and a veil that extends from the pileus margin and covers the hymenophore until pileus expansion and maturity. Boletellus ananas is the nomenclatural type of the genus Boletellus, and subsequently the type of this section of the genus as outlined by Singer (1986). This section circumscribes those taxa with dry pilei and conspicuous scales. The margin of the pileus extends as a sterile flap that covers the hymenophore when young. The true color of the context (flesh) of both the pileus and stipe is crucial to distinguishing species. This color is quickly masked by the rapid oxidation reaction when the flesh is exposed. Further, there can be a localized difference in that oxidation.
Microscopically, spore morphology is critical; there are fine cross striae on the ribs (costae) of some species visible with the light microscope. In addition, there is a difference in the width of the ribs: broader in B. ananas. Interestingly, these cross striae are not readily apparent in images seen with the SEM. However, recent SEM images of Boletellus deceptivus shows lacunae on side walls of the costae. These indicate lacunae that would refract light causing the appearance of cross-striate bands when viewed with light microscopy.
Boletellus dissiliens, originally described in 1972 from a collection gathered in 1931 in Singapore, has a few repent to suberect large squamules with age, but these are rather flattened felt-like patches on the young pileus which is pale pinkish buff or otherwise lacks obvious red or pink pigments. The pileus flesh is yellow and cyanescent. The stipe surface and flesh are white and stain orange to brownish orange within and without. The spores appear to be more similar to emodensis.
Boletellus ananiceps, imperfectly described from Australia, was reported to be very close to ananas, but lacks the cross striae on the spores. Furthermore, recent observations indicate it differs substantially in squamule development and pigment disposition in the pileus as well as oxidation reactions. Boletellus pallescens, also described from Australia (as a Strobilomyces), is a synonym of B. emodensis.
Boletellus rufescens, also imperfectly described from Australia, is reported as having a reddish stipe and cap, fine squamules on the cap, shorter spores than ananas or emodensis, AND apparently lacks the cross-striae. It might be a young form of emodensis however.
Key to sect. Boletellus
1. Pileus red, with fine scales; stipe surface red; flesh yellow in pileus and stipe, cyanescent in both pileus and stipe, but rufescent/brunnescent in base (E Asia, SE Asia, Australia)- - - B. emodensis
1. Pileus with coarse scales associated with red pigments, or with felty tan to pale brown patches lacking red pigments; flesh yellow in the pileus and cyanescent, white in the stipe and rufescent to brunnescent; stipe surface whitish or sometimes tan to pale brown in age, occasionally red only at the apex or with pale pink flushes downward - - - 2
2. Pileus tan to pale brown, LACKING red pigment, with flattened felty patches sometimes aging to coarse flattened scales (SE Asia, Australia) - - - B. dissiliens
2. Pileus scaly at first or becoming scaly, sometimes those scales becoming pyramidal or repent with age, with pink to red pigment PRESENT - - - 3
3. Pink to red pigments lying beneath superficial ocher-colored hyphae that coalesce with age to form scales; stipe lacking any red or pink expect possibly at apex; spores lacking cross-striae on the ribs (Australia) - - - B. ananiceps
3. Pink to red pigments present at base of scales or in the fibers forming the scales; these becoming coarse and repent or pyramidal with age; stipe sometimes red at apex and sometimes with pale pink flushes; spores with cross striae on ribs - - - 4
4. Pileus coarsely scaly, red and fading usually; stipe often with scattered pale pink tones; associated with Myrtaceae/Casuarinaceae (Australia) - - - B. deceptivus
4. Pileus coarsely to finely scaly, pink to red or fading to tan; stipe white to tan; associated with Pinaceae/Fagaceae (Americas) - - - Boletellus ananas