(2798) Proposal to conserve the name Cistus laevis (Fumana laevis) against C. pilosus (Cistaceae)

Abstract

(2798) Cistus laevis Cav., Icon. 2: 35. Apr–Nov 1793 [Angiosp.: Cist.], nom. cons. prop. Typus: [Spain, Valencia], “in montibus Enguerae et in Collado de Bocayrente”, 30 Jul 1791, Cavanilles (MA barcode MA 475536 [2 right-hand and 2 left-hand fragments, excl. central fragment]). (=) Cistus pilosus L., Sp. Pl.: 528. 1 Mai 1753, nom. rej. prop. Lectotypus (hic designatus): Herb. Burser XXIV: 66 (UPS No. V-175838). The family Cistaceae comprises 9 genera: Cistus L., Crocanthemum Spach, Fumana (Dunal) Spach, Halimium (Dunal) Spach, Helianthemum Mill., Hudsonia L., Lechea Kalm, Pakaraimaea Maguire & P.S. Ashton, and Tuberaria (Dunal) Spach, and about 180 species distributed in the temperate, subtropical, and tropical regions of the Northern Hemisphere. The genus Fumana is one of the most diverse and least-studied genera of the Cistaceae family, comprising 21 recognized species with high morphological diversity (Arrington & Kubitzki in Kubitzki & Bayer, Fam. Gen. Vasc. Pl. 5: 62–70. 2003; APG-IV in Bot. J. Linn. Soc. 181: 1–20. 2016; Heckenhauer & al. in Bot. J. Linn. Soc. 185: 1–26. 2017). Linnaeus (Sp. Pl.: 528. 1753) published the name Cistus pilosus through a short diagnosis (“CISTUS suffruticosus stipulatus, foliis linearibus subtus bisulcatis incanis, calycibus laevibus”) cited from Sauvages (Meth. Fol.: 147. 1751), and listed two synonyms: “ChamaeCistus foliis thymi incanis” from Bauhin (Pinax: 466. 1623) and “ChamaeCistus 4” from Clusius (Rar. Pl. Hist. 1: 74. 1601). In the protologue, two varieties were also recognised: “β Cistus stipulis quaternis, foliis lineari-ovalibus incanis, calycibus tomentosis” cited from Sauvages (l.c.: 148) and followed by the synonym “Helianthemum flore albo, folio angusto hirsuto” cited from Bauhin & Cherler (Hist. Pl. 2: 17. 1651), and “γ Cistus foliis villosis lanceolatis, axillis foliosis, stipulis subulatis” quoted from Sauvages (l.c.: 148), followed by the synonym “Helianthemum s.[sive] Cistus humilis, folio sampsuci, capitulis valde hirsutis” cited from Bauhin & Cherler (l.c. 2: 20). The protologue included the geographical provenance as “Habitat Monspelii.” Linnaeus also provided the comment “Hae tres α. β. γ. vel varietates vel valde affines: certiora determinent autoptae.” Concerning the identity of Cistus pilosus, this species has been misunderstood (see, e.g., López González in Anales Jard. Bot. Madrid 50: 40, 45. 1990; Jarvis, Order out of Chaos: 421. 2007). Sampaio (in Bol. Soc. Brot., sér. 2, 7: 132. 1931) stated that the correct name for Linnaeus's plant is Helianthemum violaceum (Cav.) Pers. (see also Jarvis, l.c.), and López González (l.c. 1990: 40, 45) argued that Helianthemum pilosum Mill. is not based on C. pilosus L., making H. pilosum (L.) Pers. a later homonym of Miller's name, an argument contrary to Proctor & Heywood (in Tutin & al., Fl. Eur. 2: 288. 1968) and Greuter & al. (in Med-Checklist 1. 1984) since they consider that new names published by Miller are new combinations based on Linnaeus's names in all those cases where the epithets coincide. On the other hand, according to Jarvis (l.c.), at least some of the original material of C. pilosus is identifiable as belonging to the genus Fumana. Jafri (in Jafri & El-Gadi, Fl. Libya 48: 22. 1977) indicated the sheet No. 689.55 (LINN; image: http://linnean-online.org/6475/) as the type of Cistus pilosus. However, as pointed out by Jarvis (l.c.), this collection lacks the relevant Species plantarum number (in this case “25”); thus, this specimen was a post-1753 addition to the herbarium and therefore not original material. So Linnaeus's Cistus pilosus has not been typified (see López González, l.c. 1990; Jarvis, l.c.). A reference to Clusius (l.c.) cited in the protologue provided an illustration, “Chamaecistus IIII”, that can be considered original material used by Linnaeus to describe Cistus pilosus. This drawing illustrates a complete plant, with opposite leaves, flowers and fruits (image available at http://www.plantillustrations.org/illustration.php?id_illustration=237597). This illustration can be identified as Fumana laevis (Cav.) Pau (in Bol. Soc. Esp. Hist. Nat. 1: 209. 1901), based on Cistus laevis Cav. (Icon. 2: 35. 1793). In addition, as indicated by Jarvis (l.c.), there is a herbarium sheet preserved at UPS-BURSER that contains additional original material of this name: Herb. Burser XXIV: 66. This sheet bears two plants of the same species, both with leaves and flowers. The sheet has a label annotated “Chamaecistus foliis Thymi incanis / Baun. / In Gallia. / 66”. It can also be identified as F. laevis. I have been unable to locate any further original material in any Linnaean or Linnaean-linked herbaria. Therefore, the only elements eligible for lectotypification, the Clusius illustration and the specimen at UPS, are identifiable as F. laevis. I designate above the specimen XXIV: 66 (UPS No. V-175838) as the lectotype of Cistus pilosus. This specimen shows important diagnostic characters, as, e.g., leaves unequally spaced on the stem, abruptly reduced above to form small bracts in the inflorescence, opposite, linear to linear-lanceolate, mucronate, with strongly revolute margins, stipulate; inflorescence 3- to 9-flowered, pedicels much longer than the subtending bracts. As already noted, this specimen matches the traditional concept of a taxon (see, e.g., Cavanilles, l.c.: 35, t. 145, fig. 1; Willkomm, Prodr. Fl. Hispan. 3: 744. 1880; Grosser in Engler, Pflanzenr. 14: 130. 1903) now recognized under the name Fumana laevis (see Molero & Rovira in Candollea 42: 524. 1987; Bolòs & Vigo, Fl. Països Catalans 2: 217. 1989; Güemes in Castroviejo & al., Fl. Iber. 3: 434. 1993; López González, Árbol. Arbust. Peníns. Ibér. 2: 455–456. 2001; Mateo & al., Fl. Valentina 2: 243. 2013; Mateo & Crespo, Claves Ilustr. Fl. Valenciana: 126. 2014). The name Fumana laevis applies to a species widely distributed in the Mediterranean, growing on warm, low-altitude coasts (0–800 m), on relatively deep soils (see Grosser, l.c.; Molero & Rovira, l.c.; Güemes, l.c.; Tison & al., Fl. France Médit.: 974. 2014). A first attempt to lectotypify this name was by Molero & Rovira (l.c.: 528), who cited a herbarium sheet (MA 475536) with no further specifications. However, according to Güemes & Muñoz-Garmendia (in Taxon 53: 1060. 2004), the sheet MA 475536 bears heterogeneous material of more than one gathering, and therefore another lectotypification was required. These authors designated as lectotype all plant fragments of the sheet MA 475536 except the central one (image available at http://161.111.171.57/herbarioV/visorVCat.php?img=MA-01-00475536). For the purpose of nomenclatural stability, I therefore propose conservation of Cistus laevis Cav. against C. pilosus L. under Art. 14.1 of the ICN (Turland & al. in Regnum Veg. 159. 2018). Rejection of this proposal would have an undesirable consequence because the name C. laevis would be included as a heterotypic synonym of the unknown and ignored Linnaean name C. pilosus, and therefore the well-known name Fumana laevis, used in a large number of works, would need to be replaced by a currently non-existent new combination, “Fumana pilosa”. An alternative solution, outright rejection of Cistus pilosus L. under Art. 56, has not been pursued, so that if C. laevis is conserved over it, the Linnaean basionym would still be available should it ever require segregation from F. laevis. Although based on current knowledge the two taxa are conspecific, the genus Fumana is still little known, and an in-depth taxonomic study is needed for the entire western Mediterranean area. The type of F. laevis, from France, is from a locality distant (for this genus) of the locus of C. pilosus (Valencia Province, Spain), both sites also present different environmental and ecological conditions. PPFG, https://orcid.org/0000-0001-7595-9302 Thanks to Mats Hjertson (UPS, Museum of Evolution, Botany Section, Uppsala University, Sweden) for the images of the herbarium sheets. Thanks to Dr. John Wiersema and Dr. John McNeill for their advice, assistance, and valuable comments that improved this proposal.