Mannia triandra (Scop.) Grolle

Dragićević, Snežana & Berg, Christian, 2023, Distribution and threat status of the liverwort Mannia triandra (Scop.) Grolle (Aytoniaceae, Marchantiophyta) in Montenegro, Cryptogamie, Bryologie 20 (10), pp. 211-217 : 212-215

Mannia triandra (Scop.) Grolle

is a small liverwort forming greyish blue-green, green or somewhat reddish thalli. The thalli, dichotomously branched (branches broadening towards the apex), when moist with reticulate surface, punctate of the simple, slightly elevated pore, in older parts becoming brown and lacunose ( Fig. 1 ). The most complete description was provided by Schill (2006). Lobes are (2)3.2-13.5(16.7) mm long and (0.3)0.9-2.8(4.9) mm wide, with margins sometimes weakly crispate and hyaline with age, purple or green. Ventral scales in two rows, sometimes only sparse or absent, overlapping each other and midline of thallus, purple with sometimes paler margins, semicircular to oblong semicircular, small slime papillae present on margin, abundant. Rhizoids smooth and pegged, hyaline and often purplish or brownish towards base. Gemmae lacking. Autoicous, antheridia located on lateral thallus lobes in a small diffuse group of c. 1 mm diameter, or, rarely, paroicous directly behind the archegoniophore. Capsule spherical, dehiscing with a lid, wall-cells thin, spores 50-65 um, yellowish, granular, exine irregularly alveolate, elaters 8-14 µm wide, yellowish, bi- or trispiral ( Damsholt 2002; Schill 2006). The closest species with which Mannia triandra could be confused is Mannia pilosa (Hornem.) Frye & L.Clark. This is also autoicous, but the antheridia of this species are located on small, ventral branches.

It seems to be an ephemeral, short lived species ( Schill 2006), usually disappearing during the dry summer period after spore dispersal in early spring ( Németh & Papp 2011). Mannia triandra prefers more shady and sheltered habitats, damp ledges, rock crevices, slopes in forests and ravines, often in north or east exposition, on young soil accumulations or on limestone, sandstone, schist, or dolomite rock ( Schill 2006; Németh & Papp 2011), or even on moist tree roots (Strgulc Krajšek & Martinčič 2017). It has a holarctic distribution, but is primarily found in Eastern North America and in Europe, and rare in Eastern Asia ( Borovichev & Bakalin 2016). It grows from sea level to the subalpine altitudinal zone, from 40-2200 (3450) m a.s.l. ( Schill 2006). It occurs mainly in montane-subalpine regions in the European Alps, although it is also found in the lower regions of central and southern Europe ( Németh & Papp 2011). According to Hodgetts & Lockhart (2020), it is present in all countries around the Alps, Scandinavia, Central and Eastern Europe and the western and northern Balkan peninsula. It is also known from China, Japan and Russia ( Németh & Papp 2011).

In Europe, Mannia triandra is considered rare ( ECCB 1995). In the latest Red List of European bryophytes, it is listed as vulnerable (VU) by criteria D1 ( Hodgetts et al. 2019). It is a species of Annex II of the Habitat Directive (plant species of community interest whose conservation requires the designation of special areas of conservation) and of Appendix I of the Bern Convention (species of special protection). It has been protected in Montenegro by national legislation since 2006 (Official Gazette of Republic of Montenegro, no 76/06, 12 December 2006).

Comparatively little is known about this rare species in Europe, and even less in Montenegro. We would like to contribute to the knowledge of the European situation and the threats to the species with new results from Montenegro.

RESULTS

LITERATURE DATA

According to Pavletić (1955), the first data about Mannia triandra in Montenegro were provided by Dörfler-Schiffner in Klemeni, c. 160 m a.s.l. near the Montenegrin-Albanian border. We did not consider this data because to our knowledge, this locality is outside Montenegro. The first information about the existence of Mannia triandra in Montenegro was given by Josef Duda. He reported an occurrence at Rijeka Crnojevića based on the bryophyte collections of Günther Beck-Mannagetta, which are kept in the Herbarium of the Botanical Department of the Faculty of Science of Charles University in Prague ( Duda 1965). Further data were provided by Bischler & Jovet-Ast (1974) for a few places in the southern and continental part of Montenegro: Orjen, Knežlaz; Boka Kotorska, above Risan, Rvaši; Lovćen, Njeguši, Krstac; Rumija, Dobovici. More recently, Papp et al. (2019) found Mannia triandra in the Prokletije Mts near Gusinje, Dolina Grebaja and from Treća livada to Kotlovi. Summarizing this literature data, seven sites of Mannia triandra are known in Montenegro.

Except for recently published data from the Prokletije Mts area ( Papp et al. 2019), the literature did not provide detailed information on habitats and population status, nor did it address threat status.

HABITATS AND ECOLOGY OF MONTENEGRIN POPULATIONS

We found Mannia triandra in areas from near the coast to higher mountains (altitudinal range from 40 to 1720 m a.s.l.). It grows in rock crevices, sheltered hollows or small caves with sparse vegetation along roadside embankments, included or at the base of carbonate rocks, in pastures, dry grassland and other non-forest habitats, as well as on very old Pinus heldreichii Christ pine forests with beech (Orjen Mt, Maganik Mt). The macrohabitat is mostly in full light, but the microhabitat is often sheltered or north exposed, providing more moist and cooler conditions. Our impression is that species has a preference for shaded and relatively mesic sites. Microhabitats are rather small, and mostly covering only several square decimetres. It occurs on the soil, or on thin soil layers over limestone rock, where Mannia triandra is often the only species.

FIELD DATA

During our research conducted in 2016 and 2019-2022 (mapping of Natura 2000 habitats and species), we registered Mannia triandra in the following localities:

Lovćen Mt Cetinje, from Dubovik to Njeguši, open rocky slopes near road, 42°25’50.5”N, 18°51’43.2”E, small cave under a limestone rock, north exposure, 990 m a.s.l., 24.II.2020, leg./det. C. Berg & S. Dragićević).

Njeguši , open rocky slopes near road, 42°25’56.7”N, 18°48’34.2”E, under a limestone rock, north exposure, 910 m a.s.l., 24.II.2020, leg./det. C. Berg & S. Dragićević.

Between Štirovnik and Jezerski vrh, open rocky slopes, small cave in a limestone rock, south-west exposure, 42°24’14.9”N, 18°49’28.1”E, 1335 m a.s.l., 30.VI.2020, leg./det. S. Dragićević.

Skadar Lake Old road from Virpazar to Rijeka Crnojevića, Komarno , very open forests of Mediterranean thermophilic vegetation, 42°18’36.0”N, 19°02’59.9”E, under a limestone rock on soil, east exposure, 100 m a.s.l., 30.VII.2016, leg./det. S. Dragićević.

From Virpazar to Ostros , thermophilic rock vegetation, small caves with sparse vegetation at the base of carbonate rocks, 42°14’09.5”N, 19°06’13.5”E, north-east exposure, 100 m a.s.l., 25.II.2020, leg./det. C. Berg & S. Dragićević.

Godinje , rocky slopes near road, 42°13’15.9”N, 19°06’51.4”E, on thin soil in north exposure, 40 m a.s.l., 25.II.2020, leg./ det. C. Berg & S. Dragićević.

Above Seoca, Carpinus orientalis Mill. shrubland, 42°12’37.7”N, 19°08’59.1”E, deep carbonate rock fissure, in south exposure, 300 m a.s.l., 25.II.2020, leg./det. C. Berg & S. Dragićević.

Turning towards Vučedabići , open rocky slopes, 42°12’03.5”N, 19°09’35.9”E, carbonate rock fissure in north-east exposure, 430 m a.s.l., 25.II.2020, leg./det. C. Berg & S. Dragićević.

Above Karanikići , open rocky slopes, 42°11’12.2”N, 19°10’14.3”E, carbonate rock fissure, in north exposure, 430 m a.s.l., 25.II.2020, leg./det. C. Berg & S. Dragićević.

Above Murići , dry calcareous grassland, 42°09’30.9”N, 19°12’33.4”E, small hollow in north-east exposure, 250 m a.s.l., 25.II.2020, leg./det. C. Berg & S. Dragićević.

Above Murići , 42°09’19.3”N, 19°12’33.2”E, under a calcareous block in an erosion gorge in north exposure, 270 m a.s.l., 25.II.2020, leg./det. C. Berg & S. Dragićević.

Rumija Mt Along the road from Ulcinj to Vladimir, open rocky slopes near road, 41°59’01.0”N, 19°15’55.4”E, under a limestone rock, west exposure, 110 m a.s.l., 26.II.2020, leg./det. C. Berg & S. Dragićević.

Katunska nahija Above village Štitari, along the hiking trail, open rocky habitats, around the thermophilic forest with Quercus cerris L., Q.pubescens Willd. , Ostrya carpinifolia Scop. , Carpinus orientalis , Juniperus oxycedrus L., Petteria ramentacea (Sieber) C.Presl , 530 m a.s.l., southwest exposure, 42°25’54.0”N, 19°00’35.7”E, 20.V.2019 and 14.III.2020, leg./det. S. Dragićević.

Above village Štitari , thermophilic forest, 42°25’54.7”N, 19°00’46.2”E, under a crevices in limestone rocks, on open soil, east exposure, 475 m a.s.l., 20.V.2019 and 14.III.2020, leg./det. S. Dragićević.

Maganik Mt Very old Pinus heldreichii -forest, but largely degraded by fire (Natura 2000: 95A0 High oro-Mediterranean pine forests), hiking trail to Kurozeb, 42°44’45.2”N, 19°13’27.8”E, under a limestone rock, on soil, south exposure, 1720 m a.s.l., 7.XI.2020, leg./det. S. Dragićević.

Orjen Mt Sedlo , small pasture rockery in the beech ( Fagus sylvatica L.) and munika forest ( Pinus heldreichii ) (Natura 2000:95A0 High oro-Mediterranean pine forests), 42°33’25.4”N, 18°33’19.3”E, under a limestone rock, on soil, east exposure, 1575 m a.s.l., 12.IX.2021, leg./det. S. Dragićević.

Tuzi municipality Degradeted Mediterranean thermophilic forest vegetation ( Colutea arborescens L., Ficus carica L., Paliurus spina-christi Mill. , Phillyrea latifolia L., Ostrya carpinifolia , Carpinus orientalis , Rosa sempervirens L., Juniperus oxycedrus , Smilax aspera L., Phlomis fruticosa L., etc.), under a limestone rock, 42°21’55.2”N, 19°24’20.6”E, north exposure, 520 m a.s.l., 24-25.IV.2022, leg./det. S. Dragićević & D. Saveljić ( Fig. 2 ).

Degradeted Mediterranean thermophilic forest vegetation, in a limestone rock crevice, 42°22’11.7”N, 19°25’14.5”E, west exposure, 670 m a.s.l., 24-25.IV.2022, leg./det. S. Dragićević & D. Saveljić.

Degradeted Mediterranean thermophilic forest vegetation, 42°19’36.6”N, 19°23’39.9”E, in a limestone rock crevice, north exposure, 140 m a.s.l., 24-25.IV.2022, leg./det. S. Dragićević & D. Saveljić.

OCCURRENCE AND ECOLOGY

We found Mannia triandra predominantly in shady, sheltered microhabitats on open ground, mostly without any other accompanying species, or with some short-living pioneer mosses. Such situations can be found particularly in small caves up to approximately 50 cm deep under rocks, stones or overhangs, but also in deep rock crevices. We found it in altitudes between 40 and 1720 m a.s.l. In conjunction with a north or northeast exposure (50% of all samplings) or east exposure (another 25% of all samplings), a comparatively cool microclimate is created. The species covers his water requirement mainly from soil moisture, air humidity and fog, because the places are usually not directly reached by rain, and dew rarely falls in such places. Southern exposures are rare, but can be found at higher altitudes.

THREATS

Threats to bryophytes are complex and often difficult to categorise because of synergistic effects (e.g. climate change and increased fire frequency), and it is hard to determine which threat is the key driver impacting a bryophyte ( Hodgetts et al. 2019). According to Schill (2006), Mannia triandra sometimes disappears in some habitats from one year to the next depending on climatic conditions. Because historical data are lacking, it is not possible to assess population trends in Montenegro. Also, the estimation of the Red List criteria is difficult. Consequently, some general threats can only be confirmed in the field, depending on the habitat situation. The species highly depends on the microclimate of the habitat. This particular situation can quickly disappear in the course of climate change if summers in the Mediterranean become hotter and drier. Populations growing along mountain trails are in same way endangered by trampling and littering. The same applies for the occurrences along embarkments of old and small country roads around Skadar Lake, where we found the most important populations ( Fig. 3 ). If these roads are reconstructed and widened as part of Montenegro’s economic development, this could destroy large parts of the Mannia triandra populations.

Therefore, we can definitely assume at least a potential endangerment of the species in Montenegro. Applying the IUCN criteria for threat status, we note that the low extent of occurrence (criterion B1), the area of occupancy and number of sites (criterion B2), the extremely small population size of <250 individuals (criterion D), as well as the uncertainties in analyzing the criteria, argue in favor of a classification as endangered (VU) in Montenegro.

Figures

FIG. 1. — Mannia triandra (Scop.) Grolle in Montenegro (A), with carpocephala (B).

FIG. 2. — Microhabitat of Mannia triandra (Scop.) Grolle in a west exposed limestone rock crevice in Tuzy municipally (red arrow).

FIG. 3. — Distribution map of Mannia triandra (Scop.) Grolle in Montenegro. Orange dots are literature data (1965-2019), and black rings are new field data (2016-2022) given in the text.