The concept employed here is generally that of Singer (1986) but with modification and clarification of species characteristics. There has been considerable confusion in distinguishing among these species. The lack of attention by some to the manifestation of the ornamentation at the apex of the spore has contributed to this confusion.

***With recent molecular phylogenetic studies, e.g., Qin et al. Mycosphere 16(1): 3544. (2025), B. elatus has been inferred to belong to a distinct genus, Boletellopsis. In addition, studies by Gelardi et al. Mycol. Progress 25: 18. (2026), a possibly undescribed entity from Guatemala (referred to as an Aureoboletus sp.), is sister to B. elatus while B. singeri is placed in Boletellus s. str. However, in that latter paper, longicollis is inferred to belong in Aureoboletus.

In longicollis and singeri, the apex of the spore is cleaved by the grooves or channels that separate adjacent ribs (costae), whereas elatus and jalapensis possess a shallow circular depression or indentation around which the ribs coalesce. Spore morphology seen with SEM and Light Microscope clearly illustrate this difference.

At present we can distinguish 4 taxa based on spore morphology, presence/absence of a veil, and to a lesser extent, viscidity/glutinosity of basidiome surfaces. 

**REH is grateful to E. Nagasawa (Japan) for material of B. longicollis & B. elatus; B. Ortiz-Santana (Madison, WI) for material of B. singeri, and the herbaria at Field Museum (F) and Guadalajara (IBUG) for loan of specimens from Japan and Mexico.

Key to Species

1. Basidiomata viscid-glutinous and with a veil; costate ornamentation of the spores typically continuous from pole to pole, not united at apex; spore apex traversed by a continuous fissure or fissures --- 2

      2. Spores broadly ellipsoid to ovoid, (9.5-)11-14.5 µm long; Japan to SE Asia --- Aureoboletus longicollis (Ces.) N.K. Zeng & Ming Zhang [SEM of spores]

      2. Spores fusoid cylindric, 11.2-18.4 µm long; Mexico to Central America --- Boletellus singeri Gonz.-Veláz. & R. Valenz. [SEM of spores]

1. Basidiomata lacking a veil, viscid glutinous or not; costate ornamentation of the spores frequently foreshortened and attenuated, occasionally continuous from pole to pole, united at the apex around a shallow, circular depression --- 3

     3. Basidiomata dry overall, rarely subviscid on the pileus when mature, subtomentose; Japan and Nepal --- Offsite Image or Boletellopsis elatus (Nagasawa) [SEM of spores]

     3. Basidiomata slimy overall; Mexico --- Boletellus jalapensis (Murr.) Gilbert [SEM of spores]