A new species and new records of Leptogium ( Ach . ) Gray ( Collemataceae , Peltigerales ) from Rio Grande do Sul State with an identification key for the genus

Specimens of leptogium collected in ten localities from the State of Rio Grande do Sul were studied. Sixteen species were found of 28 records mentioned to the state, which represents around 57% of the Leptogium diversity known for Rio Grande do Sul. leptogium exaratum is proposed as a new species. Leptogium atlanticum, L. milligranum and L. vesiculosum are reported for the first time to the state. The lectotype of l. javanicum is reported here and detailed descriptions are provided to the examined specimens. An identification key is showed with all the 28 mentioned species of Leptogium. It is the first published taxonomic key for Leptogium from Rio Grande do Sul, the State with the highest diversity of this genus in Brazil.

This work aims to study the genus Leptogium from Rio grande do Sul State mainly through the HAS and HURg herbaria materials, updating the checklist of the state.We also propose a new species, include two new citations and the first identification key to the genus Leptogium for Rio grande do Sul.

MATERIALS AND METHODS
The specimens were collected during lichenological field works in ten municipalities in the State of Rio grande do Sul: Campo Bom, Caraá, Maquiné, Parobé, Pelotas, Rio grande, Rolante, Santo Antônio da Patrulha, São leopoldo and Taquara.
Forest fragments, urban and rural areas constitute the main landscape of these municipalities, with average altitude varying from 6 to 130 m and climate classified as subtropical humid, Cfa type according to Köppen's classification (Alvares et al. 2013).The original vegetation in most of the municipalities is characterized by semideciduous forests (Anschau 2016) -Campo Bom, Taquara, São leopoldo, Parobé, Rolante, and Santo Antônio da Patrulha, while some municipalities are composed of Atlantic rainforests, with areas of semideciduous and mixed Araucaria forests (Sevegnani and Baptista 1996) -Caraá and Maquiné; and others are mainly represented by restinga forests and grasslands (Burger and Ramos 2007) -Rio grande and Pelotas.
Most of the collected specimens are deposited in HAS herbarium and some of them in the HURg and the CgMS herbaria.All studied material was described according to the protocol of Kitaura (2012) and Kitaura et al. (2015).
The term duplicate of lectotype was used to design a true piece of the lectotype specimen, according to Kitaura et al. (2013).
Neither the type material nor the material reported to Rio grande do Sul of Leptogium coralloideum (Meyen and Flot.)Vain., L. diaphanum (Sw.)Mont., L. moluccanum, L. pichneum, L. puiggarii and L. ulvaceum were revised during the current study, but the original descriptions (protologues) were used to prepare the identification key.
Lichen photographs were taken with a Scanjet 5590 and with a Canon RebelT3i coupled on an Olympus Sz stereomicroscopy and on an Olympus CX22leD microscopy.
Notes: Leptogium atlanticum is characterized by the upper surface with irregular to longitudinal rugulose under 20× magnification, lobules usually rounded on the lamina and margin of the thallus (Figure 1a).Helicoidal columnar hyphae were observed in the material from Rio grande do Sul as in the specimens studied by Kitaura et al. (2015).
This species is common in forests near to the coast in São Paulo State (Kitaura et al. 2015), but it is rare in Rio grande do Sul.Leptogium atlanticum was commonly confused with L. denticulatum, but it does not have lobules on the thallus and the apothecia are ornamented by denticules (Kitaura et al. 2015).
2. Leptogium austroamericanum (Malme) C. W. Dodge, Ann Missouri Bot Gard 20: 419. 1933 Thallus foliose, 2.0-10.0cm broad, grayish to fluorescent light, opaque, matt, gray with yellowish regions under stereomicroscope.lobes 2.0-5.0 mm wide, agglomerated, attached in points, irregular, upper surface smooth at naked eye, irregularly wrinkled under 20× magnification; apices rounded to irregular, ascending, smooth to ornamented; lateral margins ascending and more than 70% of the found species were revised.Most of the mentioned type species was collected originally in tropical regions and all names were considered as good species, except for Leptogium tremelloides.
One new species (L.exaratum) and three new records including L. atlanticum, L. milligranum and L. vesiculosum to Rio grande do Sul State were found from revised ca.120 specimens deposited in HAS and HURg herbaria.
Notes: Leptogium austroamericanum is characterized by the upper surface irregularly wrinkled under 20× magnification (Figure 1b) and isidia usually cylindrical with withered appearance.
This species is common in Rio grande do Sul State, but the specimens were collected sterile.
Specimens Notes: Leptogium azureum is characterized by the smooth thallus and apothecia with pedicel originated from the thallus, with 0.3-1.5 mm high (Figure 1c).
This species has wide distribution (Aragón et al. 2004), but it is a complex of species and further studies are necessary.
The apothecia have euparaplectenchymatous proper margin (Jørgensen and James 1983) that gives a yellowish color to the amphithecia.
The image of Leptogium cochleatum published by Jorgensen and James (1983) shows one specimen with subpedicellate apothecia, which differs from L. azureum that is constituted by pedicellate apothecia.Aragón et al. (2005), however, described L. cochleatum as having sessile apothecia, but it is indeed subpedicellate, as shown by Jørgensen and James (1983).
The type is part of linnaeus collection from lINN herbarium, and the material must be studied on the museum.

Distribution known to RS: See Spielmann (2006).
Notes: Leptogium coralloideum i s characterized by the wrinkled and isidiate upper surface.The apothecia have paraplectenchymatous subhymenial tissue with various layers and thalline exciple cortex constituted by one layer of cells (Verdon 1992).
Leptogium cyanescens differs from L. austroamericanum by the type of upper surface.The upper surface of L. cyanescens is usually smooth whereas the upper surface is irregularly wrinkled in L. austroamericanum.Both species have cylindrical isidia with withered appearance.
Notes: Leptogium denticulatum has smooth upper surface when observed to naked eye and denticules restrict only to the margin of apothecia.
Lobules and denticules are lacking on the thallus.
The lobules are flatted and differ from the cylindrical isidia of L. austroamericanum and L. cyanescens.
Leptogium diaphanum was mentioned to São Paulo and Paraná States (I.P.R. Cunha, unpublished data), but the new citation was not published.
The type is probably deposited in PC herbarium, but we were not able to make contact with its curator.
Leptogium granulans as well as L. exaratum are isidiate species, but L. granulans have isidia restrict to the margin and lamina of the thallus, whereas L. exaratum have isidia on the thallus, pedicel and apothecia.Furthermore, the form of the isidia is distinct between L. granulans and L. exaratum.The isidia of L. granulans are granular, moniliform (piled up) to irregular branched (M.J. Kitaura, unpublished data), whereas the isidia of L. exaratum is usually cylindrical, simple to irregular branched.
Leptogium javanicum has inflated pedicel as L. exaratum and L. granulans, but L. granulans and L. exaratum are isidiate species whereas L. javanicum does not have isidia.
The epithet exaratum, from latin, refers to deep ridges like the deep longitudinal ridges found on the pedicel of L. exaratum, L. granulans and L. javanicum.
Specimens from Rio grande do Sul are attached mainly by agglutinated hyphae (rhizinelike), despite the presence of hairs, whereas that the type specimen (Degelius s/n) is attached only by hairs on the substrate.The rhizinae are constituted by cylindrical hyphae, while the hairs are composed by spherical hyphae.This is the first record of hairy species constituted by spherical cells, with rhizinae.Previously, there was only the record of beard-like hairs constituted by cylindrical and spherical cells, like in L. velutinum (Kitaura et al. 2014).
The development of isidium was considered an important taxonomical characteristic in Leptogium saturninum group (Stone et al. 2016).We found different isidia in Rio Grande do Sul specimens, when compared to L. hibernicum type, but further studies are necessary.The isidia from Rio grande do Sul specimens are spherical when young and cylindrical with age, branching on the apices, whereas the isidia of L. hibernicum are granular when young, remaining granular to branching with age.
The type of Leptogium hibernicum also has lobuloid or cerebroid structures on the lamina that are not found in Rio grande do Sul specimens.
Notes: Leptogium involutum has involute lobe margins, ridged upper surface and hairs with cylindrical cells.
Leptogium hibernicum is an isidiate species and differs from L. involutum that is a non-isidiate species.
Leptogium isidiosellum and L. coralloideum are ridged species with isidia, but differ mainly by the tissues of apothecia.The type of L. coralloideum was not studied yet and other differences could be found.Leptogium isidiosellum has a thick cortex on the thalline exciple whereas L. coralloideum has a thalline exciple constituted by one layer of cells as the apothecia of L. phyllocarpum.
The material Junghuhn s/n, designated as holotype of Stephanephorus javanicus Mont. is a syntype with two different species of Leptogium, and one lectotype must be selected according to the ICN.The specimens in type collection of L. javanicum were reported as 1 and 2. The fragment 1 is designated as the lectotype of L. javanicum, whereas the fragment 2 is L. cf.cyanescens.
Aino Henssen, on the label of the material, selected specimen 1 as the lectotype in 1966, but she did not publish her choice.
In Rio grande do Sul, L. brebissonii and L. megapotamicum have transversely septate ascospores.However, L. brebissonii has isidia and L. megapotamicum is a non-isidiate species.
Known distribution to RS: New record to Rio grande do Sul, but previously mentioned to São Paulo State.
Therefore, Leptogium brebissonii and L. milligranum are usually found sterile and they can be differentiated by the type of isidia.Leptogium milligranum has isidia granular, simple, moniliform to grouped whereas L. brebissonii has isidia granular to short cylindrical, simple to branched at the apices.
Leptogium milligranum can be confused as L. isidiosellum.The first is constituted by moniliform isidia that has cylindrical appearance, whereas the last is constituted by cylindrical to irregular isidia.
Apothecia ornaments were found of various sizes and forms (Martins 2197 and 2847).They vary from high ridges to collar structures (lobules with fused base on the apices of the apothecia).Probably, the specimens of Rio grande do Sul are not L. phyllocarpum stricto sensu, but further studies are still necessary.
Notes: Leptogium sessile is characterized by thallus with longitudinal wrinkles higher than irregular wrinkles, apothecia immerse to sessile, and circular wrinkles on the apices of apothecia.
The amphithecia is concolorous with the thallus and the thalline exciple is constituted by one layer of isodiametric cells.Leptogium sessile is the only species reported to Rio grande do Sul with immerse to sessile apothecia.Leptogium cochleatum and L. moluccanum have subpedicellate apothecia and L. azureum has pedicellate apothecia, all species with thick cortex on the thalline exciple.
Notes: Leptogium subjuressianum is characterized by the presence of hairs constituted by cylindrical cells with arachnoid appearance.Leptogium subjuressianum has rounded lobules on the margin of the thallus and differs from L. juressianum that has lacinules, elongated ornaments (Kitaura and Marcelli 2012).
Leptogium involutum has usually hairs on the lower side with velvety appearance, whereas L. subjuressianum has hairy upper surface with arachnoid appearance.
The hairs of L. subjuressianum are constituted by cylindrical cells, which differ from the hairs of L. hibernicum that are constituted by spherical cells.
Therefore, Leptogium moluccanum (Pers.)Vain.was kept as good species (Dodge 1933) and we also considered them as two distinct species.Note: Leptogium vesiculosum is characterized by the smooth thallus at naked eye, the inflated pedicel and the smooth amphithecia that is concolorous with the thallus (Figure 5b).
Leptogium vesiculosum differs from L. javanicum by the margin of the apothecia and the type of amphithecia.Leptogium vesiculosum has the margin of apothecia concolorous with the thallus and amphithecia smooth whereas that L. javanicum has margin of apothecia beige, and bullate projections on the apex of amphithecia.
The material identified by Malme (1924) as Leptogium tremelloides, Malme 492 B, Malme 534, Malme 849 B and Malme 951, were not revised by us, but they were re-determined as L. azureum by Marcelli (2002).Leptogium fleigiae, L. conglutinatum and L. paulistanum were also recorded in the list of Leptogium at the HAS Herbarium (SpeciesLink), but these species are not published and are considered as invalid names, although they are good species.The SpeciesLink website will be updated soon.
The State of Rio grande do Sul has the highest known diversity of Leptogium from Brazil with 28 cited species, but further studies are necessary and the diversity can be higher than showed here.

Leptogium
FROM RIO gRANDe DO SUl STATe An Acad Bras Cienc (2019) 91(1) e20180313 3 | 26 Known distribution to RS: It is mentioned here by the first time and previously mentioned to Santa Catarina and São Paulo States.

Identification key to Leptogium in Rio Grande do Sul State, Brazil
Total of 16 species were documented during the study of Leptogium specimens from HAS and HURg Herbaria from Rio grande do Sul, southern Brazil, representing ca.57% of Leptogium diversity of the state.The descriptions of found species were provided by us, confirming that the species have not a wide morphological variability as thought previously.The jelly lichens have fragile appearance, but the taxonomical characteristics are keeping through special hyphae and tissues, e.g.columnar hyphae and paraplectenchymatous tissues, during the dehydration and hydration process.Leptogium exaratum is proposed as a new species; L. atlanticum, L. milligranum and L. vesiculosum are reported by the first time to the state; and the lectotype of L. javanicum was determined after being indicated by Aino Henssen in the label of the type specimen.