Brachythecium turgidum (Hartm.) Kindb.

Juan, Juan Guerra, Jiménez, Juan A., María, Omar Rodríguez & Cano, María J., 2025, Brachythecium turgidum (Hartm.) Kindb. (Brachytheciaceae) in the Oromediterranean belt of Sierra Nevada (southern Spain), Cryptogamie, Bryologie 20 (1), pp. 1-8 : 4-5

Brachythecium turgidum (Hartm.) Kindb.

Videnskabelige Meddelelser den Naturhistoriske Forening Kjøbenhavn 49: 294 ( Kindberg 1888). — Hypnum salebrosum var. turgidum Hartm., Handbok i Skandinaviens Flora (Third edition) 2: 309. 1838 ( Hartman 1838).

MATERIAL EXAMINED. — Spain • Granada, Sierra Nevada, Dehesa del Camarate , alrededores de la Piedra de los Soldados y barranco de las Chorreras ; 37°09’N, 3°15’W; 2400 m a.s.l.; 22.V.2024; leg. Guerra, Cano, Jiménez & Rodríguez; MUB 63151 .

DISTRIBUTION. — Brachythecium turgidum is a Northern Hemisphere species (cf. GBIF 2024), with arctic-alpine distribution. It is found in North America ( Ignatov 2014), Asia ( Ignatov et al. 2006) and Europe ( Hodgetts et al. 2020). In the Mediterranean Region it grows between 1900 and 2900 m a.s.l. on soils or rocks in humid mountainous areas. From the Pyrenees it is known of France, Andorra and Spain (Lérida and Barcelona provinces) ( Orgaz 2018; Brugués et al. 2021). The locality that we provide here is probably the southernmost record of the species, both in Europe and in the American continent ( Fig. 1 ).

TAXONOMICAL NOTES

Brachythecium turgidum can be confused with some other species of the genus that exist in the Iberian Peninsula. The closest species is B. glareosum (Bruch ex Spruce) Schimp. , from which it is differentiated by the orbicular-shaped, obtuse, sometimes short-apiculate pseudoparaphyllia and the alar cells of the leaves with slightly thickened walls in the old leaves. Brachythecium glareosum has markedly triangular, long-apiculate pseudoparaphyllia, and even in old leaves the walls of the alar cells are thin. Brachythecium turgidum is autoicous and B. glareosum is dioicous. The samples collected in Sierra Nevada are autoicous. Furthermore, the habitats of both species are very different, since B. turgidum is grows in high montane areas, while B. glareosum is common in forested areas at lower altitudes.

Brachythecium turgidum can also be confused with B. salebrosum (Hoffm. ex F.Weber & D.Mohr) Schimp. , since the shape of the leaves is quite similar. The most relevant difference between both species is the following, Brachythecium salebrosum has triangular to lanceolate pseudoparaphyllia, while B. turgidum has orbicular, obtuse or short-apiculate pseudoparaphyllia ( Orgaz et al. 2012). Additionally Brachythecium turgidum has entire leaf margins, sometimes with some scattered teeth at the apex, and alar cells clearly ascending up along the leaf margins. Brachythecium salebrosum has leaves with more or less denticulate leaf margins, especially towards the apex, and the alar cells forming a small group, scarcely ascending up along the leaf margins. ( Fig. 2 ).

HABITAT

Brachythecium turgidum has been found in the Oromediterranean belt of Sierra Nevada, which corresponds to those areas that have average annual temperatures between 8°C and 4°C, typical of the highest mountains of the Iberian Peninsula, always above 1600 m a.s.l. The vegetation of this belt in Sierra Nevada is characterized by the absence of trees and a thicket of junipers ( Juniperus sabina L., Juniperus communis subsp. alpina (Suter) Čelak. ), barberry ( Berberis hispanica Boiss. & Reut. ) and genisteae ( Cytisus galianoi Talavera & P.E.Gibbs , Genista versicolor Boiss. ) predominate ( Fig. 3 , top).

In the bottoms of glacial cirques, hygrophytic grasslands appear, known locally as “borreguiles”, very rich in endemic species such as Armeria splendens Webb , Carex camposii Boiss. & Reut. , Gentiana sierrae Briq. , Pinguicola nevadensis (H.Lindb.) Casper , Plantago nivalis Boiss. , Veronica nevadensis (Pau) Pau , etc. ( Blanca 2001). These grasslands are crossed by streams, with numerous species of bryophytes growing on their banks; it is in these places where B. turgidum has been found, accompanied by Bartramia ithyphylla Brid. , Brachytheciastrum collinum (Schleich. ex Müll.Hal.) Ignatov & Huttunen , Brachythecium rivulare Schimp. , Campylium stellatum (Hedw.) Lange & C.E.O.Jensen , Jungermannia hyalina Lyell , Rhizomnium punctatum (Hedw.) T.J.Kop. , Scapania undulata (L.) Dumort. and Tortula hoppeana (Schultz) Ochyra ( Fig. 3 , arrow).

Brachythecium turgidum joins an important number of arctic-alpine bryophytes present in the Sierra Nevada, such as Amphidium lapponicum (Hedw.) Schimp. , Bryum schleicheri DC. , Bryum weigelii Spreng. , Hymenoloma mulahaceni (Hohn.) Ochyra , Oncophorus virens (Hedw.) Brid. , Pohlia bolanderi (Lesq.) Broth. , Pohlia greenii Brid. , Polytrichastrum alpinum (Hedw.) G.L.Sm. , Schistidium agassizii Sull. & Lesq. , etc. ( Rams et al. 2001; Guerra 2019, 2021). The causes for the unusual number of these species present in this mountain system probably began at the end of the Tertiary Era, almost 1.7 million years ago. The climate in all of Europe suffered a progressive cooling that allowed plant species from northern and arctic latitudes to progressively advance towards southern Europe and occupy a large part of the interior and high areas of the Iberian Peninsula. The end of the Würm Glaciation and the arrival of the Holocene period marked the beginning of a progressive increase in temperatures, and these species adapted to cold climates found refuge in the heights of the Sierra Nevada, progressively adapting to the characteristics of the climate of the area, especially to its summer droughts.

Figures

FIG. 1. — Known distribution of Brachythecium turgidum (Hartm.) Kindb. in the Iberian Peninsula. The star indicates the new Spanish record reported.

FIG. 2. — Light microscope images of Brachythecium turgidum (Hartm.) Kindb.(from MUB 63151): A-C, leaves; D, apex of leaf; E, laminal cells in mid-leaf; F, leaf base with alar cells; G, alar cells; H-J, pseudoparaphyllia. Scale bar: A-C, 0.25 mm; D, 75 µm; E, 40 µm; F, 100 µm; G, 80 µm; H-J, 80 µm.

FIG. 3. — Habitat (arrow) of Brachythecium turgidum (Hartm.) Kindb. in Sierra Nevada (Spain). Photo credits: O. Rodríguez.