BRIEF DESCRIPTION: The following is based on the original description by Beauseigneur (1925).

The cap of Amanita boudieri var. beillei is 60 - 120 mm wide, convex at first, finally planar, fleshy, satiny white, then dirty white, with a nonstriate margin, appendiculate with floccose pieces of the volva. The volva is present as a dense covering of little, prominent, white pyramidal warts. The flesh is dirty white, sometimes becoming pinkish when cut.

The gills are narrowly adnate, ochraceous pink at first, becoming clay colored with age, pigmented in the entire cross-section of the gill, rather thick, with a decurrent line on the stem.

The stem is 100 - 120 × 10 - 20 mm, dirty whitish cream, stuffed, becoming hollow, squamulose below the ring zone, with a turnip-shaped bulb. The ring zone is flocculose at first, but the dirty white flocculence may disappear or persist as friable scales. The volval remains appear as two or three uneven rings on the top of the bulb and as granular or tubercular coating on the lower parts of the bulb. The flesh is pale café au lait, sometimes becoming pinkish when cut.

The spores measure 11 - 14 × 7 - 8 µm and are elongate. According to Beauseigneur, the spore print is Naples yellow. However, Gilbert (1941) states that in the material he had collected of the present taxon only one was even slightly yellow tinted. Spores measured by Neville and Poumarat (2004) are as follows: 10 -14 × 5 - 7.5 (-8) and are elongate to cylindric and amyloid. Clamps are absent at bases of basidia.

According to Neville and Poumarat (2004), Amanita boudieri var. beillei is known only from the French départemant of Landes, from which it was originally described. It is a species of the spring, and Beauseigneur said it was the only Amanita at the time he collected it.  (In the experience of Neville and Poumarat, the following species may occur at the same time and place: Amanita boudieri Barla, A. curtipes E.-J. Gilbert, and A. gilbertii Beauseign.)  Neville and Poumarat give collecting dates from the end of April to the end of May. The present taxon occurs in sandy soil; and, according to Neville and Poumarat, its woody plant associates include pines (Pinus pinaster), oaks (Quercus suber, Q. pendunculata, Q. pyrenaica, Q. ilex, and Q. robur), Cistus ladanifer, and chestnut (Castanea sativa).

In addition to the present taxon, Neville and Poumarat (1996) introduced varieties with pinkish, salmon, or brick red gills and pinkish staining flesh for A. solitaria (Bull. : Fr.) Fr. (var. subbeillei Neville & Poumarat) and A. gracilior Bas ex Bas & Honrubia (var. beilleioides Neville & Poumarat).  When he first read the article, it struck RET that the authors might be describing three taxa of Amanita subsect. Solitariae Bas that were liable to "attack" by an organism that caused the changing colors in the gills and the staining in the flesh -- reminiscent of the "yellowing syndrome" first observed in A. subsolitaria (Murrill) Murrill.  Neville and Poumarat report that their two varieties of A. boudieri can be found growing side by side as is the case with the yellowing and non-yellowing specimens of A. subsolitaria.

The consideration of a nongenetic cause for the color changes was anticipated by Gilbert (1941).  As Neville and Poumarat note, Gilbert had considered that A. beillei Beauseign. was simply a color form of A. boudieri or that the colors were caused by environmental factors such as chemicals from the ocean.  (Beauseigneur's original collecting site was littoral.)