A summary of the newly discovered localities, with the number of thalli and trees colonized by P. aurata and phorophytes, is provided in Table 1. Localities are represented on a map (Fig. 1). Populations in which more thalli were counted are Intzola and Beba, with 97 and 60 thalli respectively, which account for 73% of thalli found in this study. Populations with the highest numbers of colonized trees were Santa Leocadia and Beba, with 10 and 9, respectively. In Intzola, the population with the highest number of thalli, P. aurata was found only on three trees. Although P. aurata was found on several, mostly acid-barked, tree species, Castanea sativa Mill. and Quercus robur L. were the most common phorophytes (Table 1) on which P. aurata colonizes mostly mossy bark in rather sun-exposed situations. Remarkably, P. aurata was also found on an allochthonous planted Platanus hispanica Mill. ex Münchh. tree.

1. Albariña, Negreira, A Coruña, Galicia, 200 m, 2301 l/m², 12.3ºC (Paramos station). This is a small stand of deciduous forest, mainly with Castanea sativa, located along Albariña stream and surrounded by Eucalyptus plantations. Accompanying species were Normandina pulchella (Borrer) Nyl., Nephroma tangeriense (Maheu & A.Gillet) Zahlbr., Pannaria conoplea (Ach.) Bory, Parmeliella triptophylla (Ach.) Müll.Arg., and Sticta limbata (Sm.) Ach. Other lichen species observed in the trees around were Leucodermia leucomelos (L.) Kalb and Lobarina scrobiculata (Scop.) Nyl.

2. Beba, Mazaricos, A Coruña, Galicia. 250 m, 2243 l/m², 12.2ºC (Coto Muíño station). This well-preserved forest is located along a tributary stream of Xallas river but is threatened because of the surrounding Eucalyptus and Pinus plantations. Main tree species are Castanea sativa, Corylus avellana L., Crataegus monogyna Jacq., Quercus robur, and Sambucus nigra L. Pseudocyphellaria aurata was detected in four spots along Beba stream, growing on bark of standing trees and mostly in the south or southeast aspects. Four subpopulations were found at this locality (Table 1): Beba 1, with one and four thalli in two Quercus robur trees together with Parmeliella triptophylla. Lobarina scrobiculata, Pectenia plumbea (Lightf.) P.M.Jørg., L. Lindblom, Wedin & S. Ekman, Sticta fuliginosa (Dicks.) Ach., and Teloschistes flavicans (Sw.) Norman were observed in surrounding trees. Beba 2, with most of the thalli colonized by the lichenicolous fungus Arthonia pelvetii (Hepp. ex Linds.) H.Olivier (Fig. 2a), which might affect their survival. One Sambucus tree hosted 20 thalli from the base up to a height of c. 3 m, accompanied by Leucodermia leucomelos, Nephroma tangeriense, and Pectenia plumbea, whereas another tree had 10 thalli of P. aurata growing together with Nephroma tangeriense and Sticta limbata. The thalli growing on a mossy Sambucus nigra tree were not parasitized. Beba 3, with most of the thalli also infected by Arthonia pelvetii, which may affect the future of this subpopulation. Main accompanying species were Nephroma laevigatum Ach. and Sticta fuliginosa. Finally, Beba 4, with accompanying species Lobarina scrobiculata, Nephroma laevigatum, and Sticta fuliginosa.

3. Devesa de Anllares, Negreira, A Coruña, Galicia, ca. 270 m, 2243 l/m², 12.2ºC (Coto Muíño station). This is a very well-preserved forest along the Xallas river that lacks a protection figure and is highly threatened due to the surrounding Eucalyptus plantations and the construction of mini hydropower stations. The forest is composed mainly of Castanea sativa, Crataegus monogyna, Fraxinus excelsior L., and Quercus robur. We detected 31 thalli of Pseudocyphellaria aurata on bark of 7 different Quercus robur trees, although one of them was fallen; all the specimens were found on the southern or southwestern aspect. The number of thalli on the trees ranges between 1 to 10, and with a size that varies from 0.5 × 0.5 to 16 × 18 cm. Most thalli had only soralia but one of them had an apothecium (Fig. 2b). Accompanying species, many of them with euoceanic affinities, were Hypotrachyna sinuosa (Sm.) Hale, Leucodermia leucomelos, Ricasolia amplissima (Scop.) De Not. (Dendriscocaulon umhausense (Auersw.) Degel. state), Ricasolia virens (With.) H.H.Blom & Tønsberg, Lobaria pulmonaria (L.) Hoffm. (abundant with apothecia), Nephroma tangeriense, Normandina pulchella, Pannaria rubiginosa (Ach.) Bory, Parmeliella triptophylla, Pectenia cyanoloma (Schaer.) P.M.Jørg., L.Lindblom, Wedin & S.Ekman, P. plumbea, Sticta limbata, Sticta sylvatica (Huds.) Ach., Teloschistes flavicans, and ferns such as Dryopteris guanchica Gibby & Jermy, and Hymenophyllum tunbrigense (L.) Sm.

4. Santa Leocadia, Mazaricos, A Coruña, Galicia. 300 m, 2243 l/m², 12.2ºC (Coto Muíño station). This population is located along the Vao da Denonciña stream in a deep valley. The riparian forest along the stream harbours euoceanic ferns such as Hymenophyllum tunbrigense and Woodwardia radicans (L.) Sm. The forest is composed mainly of Corylus avellana, Crataegus monogyna, Fraxinus excelsior, Laurus nobilis L., and Quercus robur. Main accompanying species were: Leucodermia leucomelos, Lobarina scrobiculata, Nephroma tangeriense, Normandina pulchella, Pannaria rubiginosa, Parmeliella triptophylla, Sticta limbata, and S. sylvatica. Three subpopulations were found in this locality (Table 1): Santa Leocadia 1, where we found eight thalli on six trees, four Corylus avellana and two Laurus nobilis trees, respectively. Santa Leocadia 2, with two thalli on a Corylus avellana tree and two more on a Quercus robur tree. Santa Leocadia 3, with seven thalli on two Q. robur trees, from the base up to a height of c. 4 m in one of the trees.

5. Bertiz Natural Park, Bertizarana, Navarra. 200–230 m, 1508 l/m², 15.2ºC (Iñarbegi NG station). This protected area has been poorly managed since the late Middle Age and it constitutes one of the better-preserved old-growth forests in the northern Iberian Peninsula and southern Europe. Nearly the entire reserve is covered by beech (Fagus sylvatica L.) and oak (Quercus robur) forest, with an abundant presence of pollard-trees and riparious vegetation along its numerous streams. We have detected the presence of Pseudocyphellaria aurata in two spots along Aranea stream along the track towards Plazazelai, 500 m. apart from each other. Two subpopulations were found at this locality (Table 1): Bertiz 1, where we found two thalli (one big and sorediate; the other one small), found in April 2015 on the bark of Salix atrocinerea Brot., with presence of Leptogium brebissonii Mont., Pannaria conoplea, P. rubiginosa and Sticta fuliginosa, small thalli of Ricasolia virens and abundant Lobaria pulmonaria and Frullania sp. The Salix tree is located near a track and is rather sun-exposed and is rather old with numerous dead branches colonized by the polypore Daedaleopsis tricolor (Bull.) Bondartsev & Singer (Fig. 3). Two years later (23 December 2017) no thalli of P. aurata were found on the same tree, so we suspect that this subpopulation may have gone extinct. The other subpopulation is Bertiz 2, where we could see at least four thalli on a medium-sized Alnus glutinosa (L.)Gaertn. almost devoid of other lichens at the base. However, thalli of P. aurata grew at 6–8 m height with other lichens like Hypotrachyna revoluta (Flörke) Hale and Lobaria pulmonaria. One of the thalli was large (c. 15 cm diam.) and in good shape. This trunk was broken and hanging by the middle and the thalli of Pseudocyphellaria were then at 1–2 m high. As this tree was about to fall down, four small lobules were translocated to other trees in the vicinity with similar conditions. Their evolution has not been checked yet.

6. Intzola erreka, Basque Municipal Community, Pyrenées atlantiques, France; Bera-Vera de Bidasoa, Navarra. 110–200 m, 1857 l/m², 13.2ºC; obtained from Bera-Larrategaña station). This population is located c. 1 km E from Ibardin pass, along Intzola stream. The upper 1.5 km of Intzola stream is in Spain and it crosses the border with France before merging with Urdazuri-Nivelle river several kilometres downstream. Jovet referred (1941) to this site 500 m far from the milestones 18 and 19 delimiting the Spanish-French border as “ravin de Berra”, which is seemingly a misspelling of “Bera”. The actual name of the stream running between milestones 18 and 19 is Intzola or Izola (Capdevila i Subirana 2009). The zone has large deforested areas intermixed with forest stands with scattered large pollard oak trees (Quercus robur) and riparious vegetation with Alnus glutinosa, Fraxinus excelsior, Corylus avellana, and Salix atrocinerea, along with scattered planted Platanus hispanica trees. Two subpopulations were documented (Table 1): Intzola 1, which is the site reported by Jovet (1941), located where Intzola stream and a smaller tributary descending from Ibardin merge. We detected P. aurata in two non-pollarded Q. robur trees, in a rather open and light-exposed location (Fig. 4a-b). One of the trees harboured 10 thalli of P. aurata dispersed from the base up to a height of c. 8 m. Accompanying mosses and lichens are Coenogonium luteum (Dicks.) Kalb & Lücking, Flavoparmelia caperata (L.) Hale, Leptogium sp., Ricasolia virens, Parmeliella tryptophylla, Parmotrema perlatum (Huds.) M. Choisy, Pertusaria pertusa (L.) Tuck., Pertusaria flavida (DC.) J.R.Laundon, Sticta fuliginosa, Brachythecium sp., Frullania sp., Homalothecium sericeum (Hedw.) Schimp., Hypnum cupressiforme Hedw., Neckera complanata (Hedw.) Huebener, and Zygodon viridissimus (Dicks.) Brid. A second tree was hollow and burnt inside. This tree hosted 23 thalli. Accompanying species: Flavoparmelia caperata, Ricasolia virens, Normandina pulchella, Parmotrema crinitum (Ach.) M.Choisy, Nephroma laevigatum, Pertusaria sp., Brachythecium sp., Metzgeria furcata (L.) Corda, Neckera crispa Hedw., and Zygodon viridissimus (Fig. 5). Jovet (1941) described that thalli of Pseudocyphellaria aurata grew on several oak trees (“plusieurs Chênes”). Despite our efforts, 80 years later, P. aurata has only been spotted in two trees indicating that the number of colonized trees is probably in decline. The specimen collected by Jovet is deposited in PC (PC 0072622).

The second subpopulation is Intzola 2, located c. 1.7 km upstream, where two Platanus hispanica trees with large thalli of Lobaria pulmonaria (Fig. 4c-d) stand out. One of these trees hosts c. 64 thalli of Pseudocyphellaria aurata. A few more thalli were found on the ground around the tree base, attached to detached bark pieces. Accompanying species were: Lobaria pulmonaria, Ricasolia virens, Nephroma laevigatum, Brachythecium sp., Eurhynchium praelongum (Hedw.) Schimp., Metzgeria furcata, Isothecium myosuroides Brid., and Neckera complanata (Hedw.) Huebener.

Burgaz & Martínez (1999, 2003) reported Pseudocyphellaria aurata only from A Coruña in Spain and from three provinces in Portugal. However, P. aurata has been cited from more localities, and other specimens from Spain exist also in herbaria. Detail examination all these previous reports is of paramount importance to assess a possible decline of P. aurata in the Iberian Peninsula, and for the application of the criteria of the IUCN. Thus, we provide below a commented list of 11 previous reports of P. aurata in mainland Spain, listed from most recent to oldest. Most of these records were not included in Burgaz & Martínez (1999, 2003). Localities are also represented on a map (Fig. 1).

7. Caaveiro, Fragas do Eume Natural Park, A Coruña, Galicia. This locality was first reported by Carballal & al. (1985), based on a specimen collected in 1978 made by an unknown collector (SANT-Lich 133). Population size was not reported. Pseudocyphellaria aurata has not been observed again at this site, although the locality has been often visited (López de Silanes, pers. comm.). Fragas do Eume Natural Park is a well preserved and protected coastal deciduous forest, where habitat loss or degradation should not have caused decline or extinction of P. aurata during the past 40 years. Nevertheless, the lack of recent observations suggests that population size of P. aurata is very small, or even, that the species might have become extinct.

8. Bayona, Pontevedra, Galicia. A correctly identified specimen of Pseudocyphellaria aurata collected by Lázaro Ibiza is kept at the MAF herbarium (MAF-Lich 12139), but to our knowledge, this locality was never reported in his publications. Although there are no recent reports of P. aurata from Pontevedra, we consider the presence of P. aurata there very likely in the past due to suitable climatic conditions. This population, however, is likely to have disappeared as a result of habitat degradation.

9. Lekeitio (Biscay). Jovet (1941), apparently after a communication by P. Allorge, indicated that Pseudocyphellaria aurata was found “sur des Quercus dans des ravins maritimes accidentés à 25 m. de la mer, 1933”. Regrettably, no herbarium specimen supports this finding. This is a botanically remarkable locality because of the presence of rich stands of Woodwardia radicans and Stegnogramma pozoi (Lag.) K.Iwats. (Allorge & Allorge 1941), which are associated to warm hyperoceanic climates. Etayo (2009) visited this locality and could not find P. aurata there. Recently, we visited all the ravines that had forest in 1945 (Egurbideko erreka, Portuko erreka, Burgañeko erreka) covering the area between Lekeitio and Ondarroa, where P. Allorge and V. Allorge have made collections. At present, those ravines present patches of rather degraded forest with few mature oak trees, where we could not find P. aurata or any species of the Lobarion communities. We consider the presence of P. aurata in this locality feasible in the past, but it appears to have gone extinct due to habitat loss and degradation.

10. Moncayo (Zaragoza, La Rioja or Soria). This location was first cited by Colmeiro (1889) indicating “Láz.” (Blas Lázaro e Ibiza) as the collector, and was later mentioned by Lázaro e Ibiza (1898) and Longinós Navás (1903, 1908). Interestingly, a specimen labelled as collected in Moncayo, without date, is kept in the Lázaro e Ibiza herbarium (MAF-Lich 12135). The presence of P. aurata in Moncayo is unlikely since the continental climate with cold winters is unsuitable for P. aurata and for other more common species of the Lobarion alliance. However, this specimen represents beyond doubt P. aurata. Pseudocyphellaria aurata has not been observed in Moncayo again and we thus propose that the locality given in the label is incorrect.

11. Monasterio de Piedra (Zaragoza). A specimen collected by Lázaro e Ibiza in 1894 is kept in the MAF herbarium (MAF-Lich 111914). Lázaro e Ibiza omitted this locality in his account of Spanish lichens in 1898. The specimen cited above represents P. aurata beyond doubt, but no later observation of this species could be traced in Monasterio de Piedra. As in the previous case, the presence of P. aurata in this continental locality is difficult to conceive and we propose that the label locality of the specimen is incorrect.

12. Villarluengo (Teruel). This locality was mentioned by Colmeiro (1867) citing “Xarne” (Agustín Xarne) as the collector. This information might have been obtained from an unpublished list of plants by Xarne (“Plantas observadas en este término de la villa de Villarluengo”), but there are not specimens supporting it. We regard this record as very doubtful due to the oceanic requirements of P. aurata and we propose that it might be a misidentification.

13. Algeciras, Cádiz. This record corresponds to a herbarium specimen collected by Bourgeau, without date, deposited in PC (PC 0072591). This specimen was probably collected in 1849 or 1853 when E. Bourgeau (1815–1877) visited Andalusia (Carrasco & al. 2002) and was later included by Jovet (1941) in his locality list. The specimen represents undoubtedly P. aurata, and is the only one known from southern mainland Spain. Pseudocyphellaria aurata is probably extinct in this area. The species has not been detected in Andalusia (Burgaz 2014) since Bourgeau’s record, despite several lichen field surveys conducted in the Algeciras area.

14. Alcalá de los Gazules and Ubrique (Cádiz), Sauceda de Cortes (Málaga). These three localities were also listed by Colmeiro (1867) citing “Clem.” (Simón de Rojas Clemente) as collector. These localities were probably obtained by Colmeiro through an unpublished manuscripts by Clemente, or from private correspondence. Degelius (1935) also included these localities in his distribution map of P. aurata. Regrettably, most part of the Clemente herbarium is lost (González Bueno & Rico 1991) and specimens from these localities are not available. Two of us visited Alcalá de los Gazules and Sauceda de Cortes in March 2018, and although well-preserved Lobarion communities were observed in Sauceda de Cortes, P. aurata could not be found. As we have seen material of P. aurata from Algeciras, we consider these reports are likely to be correct. Although P. aurata might be extinct in the area, it should be searched for again in these localities.

15. Salamanca area. This area was marked by Degelius (Fig. 43, 1935) with an empty point on the map of Pseudocyphellaria aurata. According to our search, empty points refer to reports without a specific location and we thus suspect the source of Degelius was Lázaro e Ibiza (1920), who mentioned P. aurata in “C., S. y O.” of Spain. Although, Jovet (1941) also mentioned this locality, we think it is likely erroneous.

16. Without locality. Colmeiro (1867) listed Lagasca as the collector of this specimen of Pseudocyphellaria aurata. Nevertheless, this report seems to correspond to Pseudocyphellaria crocata, as Colmeiro merged P. aurata and P. crocata into a single species. We have checked the Spanish specimen sent by Lagasca and seen by Acharius (1810), identified as P. crocata (H-Ach without number). No other collection of P. crocata has been made in Spain ever since and this suggests, if the country information is correct and the specimen of P. crocata was indeed collected in Spain, it is very possible to have become extinct in continental Spain. An alternative is that the Spanish specimen was collected in the Canary Islands, where P. crocata is not rare, but Lagasca is not known to have travelled there.

17. Without locality. Fries (1831) listed P. aurata from Spain based on a specimen collected by L. Dufour, who travelled to Spain in 1826 (Fries 1831). However, no specimen supporting this report could be traced in the Fries herbarium (UPS-Fries).