Longest species name for a plant

According to the Kew Plant List, the longest species name for a plant is Ornithogalum adseptentrionesvergentulum, the official scientific name for, ironically, an extremely small species of asparagus (and one that has no common name), and which, including the single space between genus and species, is 39 characters long. One of approximately 180 separate species housed within the genus Ornithogalum, it constitutes one of the smallest bulb plants in existence (under 3 cm tall) and is native to an area north of Laingsburg in the western end of South Africa's Great Karoo Desert. At 50 characters long (including three intervening spaces), Acamptopappus sphaerocephalus var. sphaerocephalus is even longer. However, this is merely the name of a variety within a single species, not a species itself. The species itself, Acamptopappus sphaerocephalus, is the rayless goldenhead, a member of the aster family, Asteraceae, and is native to the southwestern USA, in particular southern California.