Fruit bodies of Boletus subluridellus have convex caps that measure 5–10 cm (2–4 in) in diameter.
The cap surface is dry and slightly sticky, with a somewhat velvety texture.
Its color is reddish to reddish-brown to orange-red.
The flesh is bright yellow before staining blue where it has been cut.
It has no discernible odor, and a slightly metallic taste.
On the cap underside, the tubes comprising the pore surface are 6–9 mm (0.24–0.35 in) long.
Near to where the cap attaches to the stipe, they are either unattached, or slightly depressed.
The dark reddish pores are small and round, numbering about 2–3 pores per mm.
The stipe measures 4–9 cm (1.6–3.5 in) long by 1.5–2.3 cm (0.6–0.9 in) thick.
It is solid (i.e., not hollow or stuffed with a pith), and roughly the same width throughout its length.
The stipe color is pale yellow, grading to reddish in the base, where it has pressed-down yellow hairs.
All parts of the fruit body (cap surface, flesh, pores, and stipe) will quickly stain blue when injured or touched.

The spore print is olive-brown.
Spores are somewhat fuse-shaped in face view, and inequilateral in profile view.
They have a smooth surface, a tiny apical pore, and dimensions of 11–15 by 4–5.5 μm, with walls about 0.2 μm thick.
The basidia (spore-bearing cells) are club-shaped, four-spored, and measure 8–12 μm thick.
Pleurocystidia (on the tube walls) are 28–42 by 6–11 μm with a 3–μm neck, whereas the cheilocystidia (on the pore edges) are narrowly club-shaped and slightly smaller, measuring 26–38 by 4–8 μm.
Pleurocystidia tend to not protrude further than sporulating basidia.
The cap cuticle comprises a 150 μm-thick layer of narrow hyphae measuring 3–5 μm more or less arranged in a trichodermium (wherein the outermost hyphae emerge roughly parallel, like hairs, perpendicular to the cap surface).
These hyphae stain red when mounted in Melzer's reagent and yellow in potassium hydroxide.
Clamp connections are absent from the hyphae.
Fruit bodies of Boletus subluridellus have convex caps that measure 5–10 cm (2–4 in) in diameter. The cap surface is dry and slightly sticky, with a somewhat velvety texture. Its color is reddish to reddish-brown to orange-red. The flesh is bright yellow before staining blue where it has been cut. It has no discernible odor, and a slightly metallic taste. On the cap underside, the tubes comprising the pore surface are 6–9 mm (0.24–0.35 in) long. Near to where the cap attaches to the stipe, they are either unattached, or slightly depressed. The dark reddish pores are small and round, numbering about 2–3 pores per mm. The stipe measures 4–9 cm (1.6–3.5 in) long by 1.5–2.3 cm (0.6–0.9 in) thick. It is solid (i.e., not hollow or stuffed with a pith), and roughly the same width throughout its length. The stipe color is pale yellow, grading to reddish in the base, where it has pressed-down yellow hairs. All parts of the fruit body (cap surface, flesh, pores, and stipe) will quickly stain blue when injured or touched.
The spore print is olive-brown. Spores are somewhat fuse-shaped in face view, and inequilateral in profile view. They have a smooth surface, a tiny apical pore, and dimensions of 11–15 by 4–5.5 μm, with walls about 0.2 μm thick. The basidia (spore-bearing cells) are club-shaped, four-spored, and measure 8–12 μm thick. Pleurocystidia (on the tube walls) are 28–42 by 6–11 μm with a 3–μm neck, whereas the cheilocystidia (on the pore edges) are narrowly club-shaped and slightly smaller, measuring 26–38 by 4–8 μm. Pleurocystidia tend to not protrude further than sporulating basidia. The cap cuticle comprises a 150 μm-thick layer of narrow hyphae measuring 3–5 μm more or less arranged in a trichodermium (wherein the outermost hyphae emerge roughly parallel, like hairs, perpendicular to the cap surface). These hyphae stain red when mounted in Melzer's reagent and yellow in potassium hydroxide. Clamp connections are absent from the hyphae.
Boletus subluridellus