Typifications of Andean Arenaria names (Caryophyllaceae), with a nomen novum Author Montesinos-Tubée, Daniel B. 0000-0002-4439-5089 Botanic Garden and Botanical Museum Berlin (BGBM), Freie Universität Berlin, Königin-Luise-Str. 6 - 8, 14195 Berlin, Germany. & Instituto Científico Michael Owen Dillon, Av. Jorge Chávez 610, Cercado, Arequipa, Peru. & Instituto de Ciencia y Gestión Ambiental de la Universidad Nacional de San Agustín de Arequipa. Calle San Agustín 108, Arequipa- Peru. & dbmtperu @ gmail. com; https: // orcid. org / 0000 - 0002 - 4439 - 5089 dbmtperu@gmail.com Author Iamonico, Duilio 0000-0001-5491-7568 Ce. R. S. I. Te. S., Viale XXIV Maggio 7, 04100 Latina, Italy. & duilio. iamonico @ uniroma 1. it; https: // orcid. org / 0000 - 0001 - 5491 - 7568 text Phytotaxa 2023 2023-01-13 579 1 54 60 http://dx.doi.org/10.1094/PDIS-04-22-0755-PDN journal article 226692 10.11646/phytotaxa.579.1.6 7526d7b5-488c-40af-ba2a-5a7a9ce6d1bf 1179-3163 7532127 Scleranthus peruvianus Muschler (1911: 460–461) provided a detailed description of of Scleranthus peruvianus , as well as the provenance (“ Peru : Saltus Coymolache supra Hualgayoc, departimento Cajamarca , in formationes fruticetis el cactacearum speciminibus composita, 4000 ― 4100 m s.m.”). A single specimen ( syntype according to the Art. 9.6 of ICN) was also reported: “WEBERBAUER n. 3985. ― Specimina florigera 11. Maii 1904. ― Herb. Berol.”. Hence, Muschler (1911: 461) explicitly referred to a specimen preserved at the Herbarium Berolinensis (the current acronym is B). However, most of the B specimens were destroyed during the World War II (see e.g., Sleumer 1949 , Hiepko 1987 ). According to Stafleu & Cowan (1988) and HUH-Index of Botanists (2013+), a large part of Weberbauer’s Herbarium and types are deposited also at MOL and USM where, therefore, duplicates of the specimen cited by Muschler (1911) in the protologue could be found there. We traced one specimen at MOL (barcode MOL00000505) bearing one plant collected by A. Weberbauer in “ Paso de Coymolache, encima de Hualgayoc (Departimento: Cajamarca ) | 4000-4100 m ” as reported on the original label. Although the date of collection is lacking, the specimen was numbered with 3985, as indicated in the protologue. Therefore, we are sure that this MOL specimen is part of the original material. It morphologically matches the Muschler’s description and it is here designated as the lectotype of the name Scleranthus peruvianus . Concerning the identity of this taxon, note firstly that it was mentioned by MacBride (1936) , Brako & Zarucchi (1993) , and Ulloa-Ulloa et al. (2017) under Scleranthus . Also, POWO (2022c) currently accepts Muschler’s species as belonging to Scleranthus . According to the detailed description given by Muschler (1911) , S. peruvianus flowers have five petals (“Petala 5, alba, subulata, calycis lacinias subaequantia”), while Scleranthus is defined as having apetalous flowers (see e.g., West & Garnock-Jones 1986 , Walters 1993 ). On the basis of our examination of the lectotype , S. peruvianus should be transferred to Arenaria due to its lanceolate-linear leaves without stipules, five free petals, two styles, and dehiscent capsules with two teeth, each with 6–10 seeds. Since an “ Arenaria peruviana ” was already validly published by Rohrbach ( Arenaria peruviana Poeppig ex Rohrbach 1872: 275 ), a nomen novum is necessary to avoid a later and illegitimate homonym (Art. 53.1 of ICN). Arenaria humboldtiana Montesinos & Iamonico , nom. nov. pro Scleranthus peruvianus Muschler (1911: 460–461) non Arenaria peruviana Poeppig ex Rohrbach (1872: 275) , nec Arenaria peruviana ( Muschler 1911: 457–458 ) Molinari (2016: 276) , nom. illeg. (later homonym; Art. 53.1 of ICN). Lectotype (designated here):— PERU . Cajamarca : Coymolache Pass , above Hualgayoc , in grassland steppes, 4000–4100 m , s.d. , Weberbauer 3985 ( MOL00000505 !, image available at https://plants.jstor.org/stable/viewer/10.5555/al.ap.specimen.mol00000505) . Etymology:― The specific epithet honours Alexander von Humboldt (1769–1859), considered as a leading mind in the natural sciences, and who worked widely in botany, but also physics, geology, and oceanology. Humboldt is known for having placed Andean flora and fauna into distinct climatic and topographic contexts and defined human impacts on climate change as potentially affecting the evolution of society. Distribution and ecology:― Arenaria humboldtiana is an endemic Peruvian species occurring in montane forests at 3800–4100 m a.s.l. (pers. obs.). Note:― By recognizing Muschler’s taxon under the genus Arenaria , Scleranthus annuus Linnaeus (1753: 406) remains as the only species (alien) of Scleranthus known to occur in South America (see e.g., POWO 2022d ). Examined specimens:― PERU . Cajamarca ; Celendín; Jalca de Kumulca, mountain pass on the road Cajamarca-Celendín, 3700 m , 26 August 2004 , Sklenar & Zapata Cruz 8712 (B101104856!); Cajamarca ; Celendín; Sorochuco, Minasconga, W of the lake, swamp areas, 3900 m , 13 December 1997 , Sánchez Vega 9226 (CPUN013316!); Cajamarca ; Celendín; Sorochuco, Minasconga, E of the lake Lucmacocha or Perol, following the path that sorrounds the lake, Jalca grasslands con rocky outcrops, 3800 m ., 4 December 2003 , Sánchez Vega et al. 2497 (CPUN16750!); Cajamarca ; Hualgayoc; Coymolache, 4000 m , 15 June 2001 , Sánchez Vega et al. 10786 (CPUN14898!).