nomen novum or replacement name is a name published as a substitute for "a legitimate or illegitimate, previously published name, which is its replaced synonym and which, when legitimate, does not provide the final epithet, name, or stem of the replacement name". For species, replacement names may be needed because the specific epithet is not available in the genus for whatever reason. Examples: Carl Linnaeus gave the herb rosemary the scientific name Rosmarinus officinalis in 1753. It is now regarded as one of many species in the genus Salvia. It cannot be transferred to this genus as "Salvia officinalis" because Linnaeus gave this name to the herb sage. An acceptable name in the genus Salvia was published by Fridolin Spenner in 1835. The replacement name is cited as Salvia rosmarinus Spenn.; the replaced synonym is Rosmarinus officinalis L. The author of the replaced synonym is not included in the citation of the replacement name. The plant name Polygonum persicaria was published by Linnaeus in 1753. In 1821, Samuel Gray transferred the species to the genus Persicaria. He could not do this using the name "Persicaria persicaria" because the ICNafp does not allow tautonyms. Accordingly, he published the replacement name Persicaria maculosa. The replacement name is Persicaria maculosa Gray; the replaced synonym is Polygonum persicaria L. Again, the author of the replaced synonym is not included in the citation of the replacement name. The fungus name Marasmius distantifolius was published by Y.S. Tan and Desjardin in 2009. Later it was discovered that this combination had already been used for a different species by William Murrill in 1915, so Tan and Desjardin's name was an illegitimate later homonym. Accordingly, in 2010 Mešić and Tkalčec published the replacement name Marasmius asiaticus for the species. The replacement name is cited as Marasmius asiaticus Mešić & Tkalčec; the replaced synonym as Marasmius distantifolius Y.S. Tan & Desjardin. In this example, the replaced synonym is illegitimate. The plant name Lycopodium densum was published by Jacques Labillardière in 1807. However, the combination had already been used for a different species by Jean-Baptiste Lamarck in 1779, so Labillardière's name is illegitimate. Werner Rothmaler knew this when in 1944 he transferred the species to the genus Lepidotis, and so explicitly published Lepidotis densa as a new name ("", ""). The replacement name is Lepidotis densa Rothm.; the replaced synonym is Lycopodium densum Labill. Even though the specific epithet in