Cistus, Linnaeus, 1753

Ferrer-Gallego, P. Pablo, Laguna, Emilio, Alonso, Ángeles & Crespo, Manuel B., 2021, Lectotype designation of Desfontaines’s name Cistus heterophyllus and its hybrid C. × clausonii (Cistaceae), Phytotaxa 491 (2), pp. 158-166 : 163

Cistus × clausonii Font Quer & Maire (1930: 59)

Type (lectotype, designated here):— [ MOROCCO]. In Atlante rifano, in dumeti infra Targuist, solo siliceo, 1000 m, 13 Jun 1929, R. C. J. E . Maire s.n., MPU (barcode MPU003405 ) (images available at https://herbier.umontpellier.fr/zoomify/zoomify. php?fichier= MPU003405 ) . Isolectotypes : MPU (barcode MPU003406 ) , P (barcode P05375267 ) .

The protologue of Cistus × clausonii , numbered “101” consists of a complete diagnosis (including the phrase “ Planta sterilis ”), followed by the geographical provenance “ Hab. inter parentes: in Algeria prope Kolea (Clauson), in Imperio Maroccano pr. Targuist, juxta Hax-Bu-Lahar, in callitrietis degradatis, ad 1000 m. alt. ( F. Q., Emberger et Maire)”.

Therefore , two gatherings are included in the protologue, a gathering from “ Algeria prope Kolea ” collected by Clauson, and a second one from “ Imperio Maroccano pr. Targuist, juxta Hax-Bu-Lahar, in callitrietis degradatis, ad 1000 m. alt. ” collected by Font Quer, Emberger and Maire. These two collections therefore represent syntypes ( ICN Art. 9.6 and Art. 40 Note 1, see Turland et al. 2018), from which a lectotype may be designated ( ICN Art. 9.12) .

Unfortunately, we have been unable to locate any material from the first gathering collected by Clauson (1817– 1860). The herbarium of this French botanist and colonial settler in Algeria, is kept at P, but no original material from “ Algeria prope Kolea ” collected by Clauson has been found. However, we traced several specimens preserved at MPU (Maire herbarium) and P herbaria. belonging to the second gathering cited in the protologue, namely the material belonging to the exsiccata “Iter Maroccanum XVIII”, collected in Targuist in June 1929 .

In the collections at MPU there are two relevant sheets. The sheet with barcode MPU 003405 bears two fragments with leaves, flowers, and an original label from Maire’s exsiccata “Iter Maroccanum XVIII”, annotated as: “× Cistus Clausonis n. hybr. / = C. albidus L. × heterophyllus Desf. (handwritten by Maire) / In Atlante rifano: in dumeti infra / Targuist, solo siliceo, 1000 m / die 13 junii”. The sheet also contains a printed label with the protologue of this species (image available at https://herbier.umontpellier.fr/zoomify/zoomify.php?fichier= MPU 003405). The sheet with barcode MPU 003406 bears a fragment wit leaves and flowers, and the same printed label with the protologue (image available at https://herbier.umontpellier.fr/zoomify/zoomify.php?fichier= MPU 003406).

On the other hand, there is a sheet of this hybrid belonging to the Maire’s gathering at P, with barcode P 05375267. This sheet bears two plant fragments well preserved, and a label handwritten by Maire with the same information that the sheet at MPU 003405: (image available at http://mediaphoto.mnhn.fr/media/1441388868095yfy0iEk797GT0f4c).

We have been unable to locate any further original material belonging to this gathering (e.g., in the Font Quer herbarium at BC). However, in the herbarium MA, with barcode MA 79272, a sheet bears material identified as C. heterophyllus and belonging to Font Quer’s exsiccata “Iter Maroccanum 1929” from Targuist (image available at http://161.111.171.57/herbarioV/visorVCat.php?img=MA-01-00079272). However, this sheet is heterogeneous, since it contains three fragments of C. heterophyllus plus two fragments that can be identified as C. × clausonii (mounted in the lower left and the upper right parts of the sheet). This sheet bears a label annotated “Hab. in callitrietis, inter Targuist et Sok-et-Tnin de Beni Hadifa (Beni Uriaguel), ad 1100 m. alt.; 22 majii”. This is the only material of C. × clausonii that has been found in a Spanish herbarium from the “Iter Maroccanum 1929”, but clearly is not original material of C. × clausonii because the collection data on the label do not match the protologue.

In fact, the third expedition of the Iter Maroccanum took place in 1929. In this expedition, Pius Font i Quer (1888–1964) collected together with Louis Emberger (1897–1969) and René Maire (1878–1949), and they visited the birch forests of Ketama and Tidiguin during the month of June. Concretely, on June 5–7 and June 12, 1929, Font Quer visited Tidiguin ( González Bueno 1988), at which time material of C. × clausonii in Hax-Bu-Lahar [Haj Boulahar] had to be collected. However, this hybrid was not distributed in Font Quer’s exsiccata “Iter Maroccanum” ( González Bueno 1988), so it seems that the only material from the gathering cited in the protologue, in which Emberger, Maire and Font Quer participated, was distributed in Maire’s exsiccata of “Iter Maroccanum”.

In conclusion, among the original material of C. × clausonii , specimens preserved at MPU and P, we designate the specimen preserved at MPU, with barcode MPU 003405 as lectotype of this name. This specimen fully matches with the current usage of the name Cistus × clausonii (see e.g., Navarro-Cano 2002, Demoly 2005, Navarro-Cano et al. 2009, 2017, Ferrer-Gallego & Laguna 2012).