Jouko Rikkinen

Jouko Rikkinen
University of Helsinki | HY · Finnish Museum of Natural History

PhD

About

153
Publications
57,534
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3,401
Citations
Citations since 2017
55 Research Items
1757 Citations
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2017201820192020202120222023050100150200250300
2017201820192020202120222023050100150200250300
2017201820192020202120222023050100150200250300
Additional affiliations
January 1998 - December 2012
University of Helsinki

Publications

Publications (153)
Article
Full-text available
The group I intron interrupting the tRNALeu UAA gene (trnL) is present in most cyanobac-terial genomes as well as in the plastids of many eukaryotic algae and all green plants. In lichen symbiotic Nostoc, the P6b stem-loop of trnL intron always involves one of two different repeat motifs, either Class I or Class II, both with unresolved evolutionar...
Article
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One of the most important issues in molecular dating studies concerns the incorporation of reliable fossil taxa into the phylogenies reconstructed from DNA sequence variation in extant taxa. Lichens are symbiotic associations between fungi and algae and/or cyanobacteria. Several lichen fossils have been used as minimum age constraints in recent stu...
Article
A new resinicolous species of the genus Chaenothecopsis (Ascomycota, Mycocaliciales) is described from resin of Agathis ovata in New Caledonia. Chaenothecopsis neocaledonica sp. nov. is the first mycocalicioid fungus to be described from the exudates of Southern Hemisphere conifers of the family Araucariaceae. It is easily distinguished from relate...
Article
Full-text available
The phylum Ascomycota is by far the largest group in the fungal kingdom. Ecologically important mutualistic associations such as mycorrhizae and lichens have evolved in this group, which are regarded as key innovations that supported the evolution of land plants. Only a few attempts have been made to date the origin of Ascomycota lineages by using...
Article
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Symbioses between cyanobacteria and lichen-forming fungi occur worldwide in a wide range of terrestrial environments, ranging from tropical rainforests to hot and cold deserts. The evolutionary success of these symbioses is evident from the wide range of fungal groups that have established associations with cyanobacteria. The diversity of symbiotic...
Article
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We surveyed tree hyrax populations living in forests, limestone rocky formations, and caves in coastal Kenya to identify the species and estimate the threat‐level populations are in. Tree hyrax vocalizations were recorded in three different habitats with passive acoustic monitoring (PAM) for a total of 84 h in January and February 2022. We also obs...
Article
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Selaginella (Selaginellales, Selaginellaceae) is the most speciose genus of lycophytes and, with approximately 750 recognized present-day species, also one of the largest genera of vascular plants. However, the evolutionary history of this species richness remains largely unresolved. Recent research suggests that Selaginella was diverse already in...
Preprint
The eastern tree hyrax is thought to be a solitarily living arboreal species of the forests of East Africa. However, in the coast of Kenya, indigenous forests have been almost entirely cleared, and some of the last tree hyrax populations live in limestone rocky formations and caves. Interestingly, they seem to be living in social groups. Here, we d...
Article
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Background Understanding the natural variability of plant resins is crucial for evaluating the chemical information stored in ambers that may support inferring palaeoenvironmental conditions. However, even among extant resin-producing plants, the variation of resinous exudates within and between tree genera and species is still poorly understood....
Article
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We studied a previously almost unknown nocturnal mammal, an apparently undescribed species of tree hyrax (Dendrohyrax sp.) in the moist montane forests of Taita Hills, Kenya. We used thermal imaging to locate tree hyraxes, observe their behavior, and to identify woody plants most frequently visited by the selective browsers. We also documented acou...
Article
Lichens are important in many modern terrestrial ecosystems, but their fossil record has been very sparse. This has limited the chances for finding any evidence of their interactions with animals in past ecosystems. Recently, the fossil record of lichens has improved significantly with the discovery of numerous new inclusions from European Paleogen...
Article
Full-text available
Fungus-growing termites and their symbiotic Termitomyces fungi are critically important carbon and nutrient recyclers in arid and semiarid environments of sub-Saharan Africa. A major proportion of plant litter produced in these ecosystems is decomposed within nest chambers of termite mounds, where temperature and humidity are kept optimal for the f...
Article
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Lichens have been widely used in traditional medicine, especially by indigenous communities worldwide. However, their slow growth and difficulties in the isolation of lichen symbionts and associated microbes have hindered the pharmaceutical utilisation of lichen-produced compounds. Advances in high-throughput sequencing techniques now permit detail...
Article
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Interactions within lichen communities include, in addition to close mutualistic associations between the main partners of specific lichen symbioses, also more elusive relationships between members of a wider symbiotic community. Here, we analyze association patterns of cyanolichen symbionts in the tropical montane forests of Taita Hills, southern...
Article
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Bird‐mediated dispersal is presumed to be important in the dissemination of many different types of organisms, but concrete evidence remains scarce. This is especially true for biota producing microscopic propagules. Tree‐dwelling birds, such as woodpeckers, would seem to represent ideal dispersal vectors for organisms growing on standing tree trun...
Article
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Tropical mountains and especially their forests are hot spots of biodiversity threatened by human population pressure and climate change. The diversity of lichens in tropical Africa is especially poorly known. Here we use the mtSSU and nuITS molecular markers together with morphology and ecology to assess Leptogium (Peltigerales, Ascomycota) divers...
Article
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Three poorly known nocturnal mammal species from the montane forests of the Taita Hills in Kenya, were studied via vocalization analysis. Here, their acoustic behaviour is described. The studied animals were the tree hyrax (Dendrohyrax sp.), the small-eared greater galago (Otolemur garnettii), and the dwarf galago (Paragalago sp.). High-quality lou...
Article
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Recently, the Society of Vertebrate Paleontology (SVP) has sent around a letter, dated 21st April, 2020 to more than 300 palaeontological journals, signed by the President, Vice President and a former President of the society (Rayfield et al. 2020). The signatories of this letter request significant changes to the common practices in palaeontology....
Article
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Fruticose lichens of the genus Usnea Dill. ex Adans. (Parmeliaceae), generally known as beard lichens, are among the most iconic epiphytic lichens in modern forest ecosystems. Many of the c. 350 currently recognized species are widely distributed and have been used as bioindicators in air pollution studies. Here we demonstrate that usneoid lichens...
Article
Stam Å, He X., Kaasalainen U., Toivonen M., Enroth J., Räsänen M. & Rikkinen J. 2020: Epiphyte colonisation of fog nets in montane forests of the Taita Hills, Kenya.-Ann. Bot. Fennici 57: 227-238. The dispersal ecology of tropical non-vascular epiphytes has rarely been experimentally investigated. We studied epiphyte colonisation on 1 × 1 m polyeth...
Article
We studied growth of three epiphytic bryophyte species in Kenya to determine their sensitivity to environmental changes. Bryophytes collected from a cool and moist upper montane forest were used to prepare 180 pendant transplants. Sixty transplants were placed in their natural habitat while 120 were transferred to two warmer and drier sites in a lo...
Article
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The spike mosses (Selaginella P.Beauv.; c. 750 species) are not only the most speciose extant genus of lycophytes, but also one of the largest land plant genera (Jermy, 1990). In addition to the exceptionally high number of living species it comprises, Selaginella is an ancient lineage believed to date back to the Carboniferous or even Devonian bas...
Article
Full-text available
Taita Mountain dwarf galago is extant in the Taita Hills of Kenya - Volume 54 Issue 2 - Hanna Rosti, Jouko Rikkinen, Petri Pellikka, Simon Bearder, James Mwang'ombe Mwamodenyi
Article
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Resinicolous fungi constitute a heterogeneous assemblage of fungi that live on fresh and solidified plant resins. The genus Sarea includes, according to current knowledge, two species, S. resinae and S. difformis . In contrast to other resinicolous discomycetes, which are placed in genera also including non-resinicolous species, Sarea species only...
Article
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Myxomycetes constitute a group within the Amoebozoa well known for their motile plasmodia and morphologically complex fruiting bodies. One obstacle hindering studies of myxomycete evolution is that their fossils are exceedingly rare, so evolutionary analyses of this supposedly ancient lineage of amoebozoans are restricted to extant taxa. Molecular...
Article
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Fungus-growing termites of the genus Macrotermes cultivate symbiotic fungi (Termitomyces) in their underground nest chambers to degrade plant matter collected from the environment. Although the general mechanism of food processing is relatively well-known, it has remained unclear whether the termites get their nutrition primarily from the fungal my...
Article
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Lichens, symbiotic consortia of lichen-forming fungi and their photosynthetic partners have long had an extremely poor fossil record. However, recently over 150 new lichens were identified from European Paleogene amber and here we analyse crustose lichens from the new material. Three fossil lichens belong to the extant genus Ochrolechia (Ochrolechi...
Article
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Based on previous literature and our own collections, we list 285 bryophyte species (142 liverworts, 143 mosses) from the Taita Hills region (including Mt. Kasigau and Maktau Hill) in SE Kenya. New records for Kenya include the liverworts Archilejeunea elobulata Steph., Bazzania nitida (F. Weber) Grolle, Cololejeunea grossepapillosa (Horik.) N. Kit...
Article
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We studied the genotype diversity of cyanobacterial symbionts in the predominately terricolous cyanolichen genus Peltigera (Peltigerales, Lecanoromycetes) in Estonia. Our sampling comprised 252 lichen specimens collected in grasslands and forests from different parts of the country, which represented all common Peltigera taxa in the region. The cya...
Article
Background and aims: In order to re-establish lichen symbiosis, fungal spores must first germinate and then associate with a compatible photobiont. To detect possible establishment limitations in a sexually reproducing cyanolichen species, we studied ascospore germination, photobiont growth and photobiont association patterns in Pectenia plumbea....
Article
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Background Large and complex mounds built by termites of the genus Macrotermes characterize many dry African landscapes, including the savannas, bushlands, and dry forests of the Tsavo Ecosystem in southern Kenya. The termites live in obligate symbiosis with filamentous fungi of the genus Termitomyces . The insects collect dead plant material from...
Article
Amber is a valuable source of Mesozoic and Cenozoic fossil fungi. The earliest amber‐preserved fungi were described in the nineteenth and early twentieth centuries from Eocene Baltic amber. In 1907, Richard Klebs summarized the legacy of Robert Caspary based on his specimens, research notes and publications. This treatise contains descriptions and...
Article
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Krogia borneensis Kistenich & Timdal, K. isidiata Kistenich & Timdal and K. macrophylla Kistenich & Timdal are described as new species, the first from Borneo and the two latter from New Caledonia. The new species are supported by morphology, secondary chemistry and DNA sequence data. Krogia borneen-sis and K. isidiata contain sekikaic and homoseki...
Conference Paper
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More than 400 million years ago, before plants had leaves and roots, they had established intimate relationships with fungi. Fungi at that time may already have been key ecosystem players that recycled carbon, solubilized and redistributed minerals, and colonized plants and other organisms. We will assess fossil and phylogenetic evidence for the ki...
Article
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Marine microorganisms trapped in amber are extremely rare in the fossil record, and the few existing inclusions recovered so far originate from very few pieces of Cretaceous amber from France. Marine macroscopic inclusions are also very rare and were recently described from Cretaceous Burmese amber and Early Miocene Mexican amber. Whereas a coastal...
Article
Calicioid lichens and fungi are a polyphyletic grouping of tiny ascomycetes that accumulate a persistent spore mass (mazaedium) on top of their usually well-stalked ascomata (‘mazaediate fungi’). In addition to extant forms, six fossils of the group were previously known from European Paleogene amber. Here we report nine new fossils and analyze the...
Article
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Amber is fossilised plant resin. It can be used to provide insights into the terrestrial conditions at the time the original resin was exuded. Amber research thus can inform many aspects of palaeontology, from the recovery and description of enclosed fossil organisms (biological inclusions) to attempts at reconstruction of past climates and environ...
Article
Terrestrial ecosystems of the long-isolated former Gondwanan landmass of New Zealand are hotspots of modern global biodiversity, based on the level of endemism and distinctiveness of the biota. However, little is known of the evolutionary history of the rarely preserved but diverse, distinctive, fragile, mainly soft-bodied organisms such as arthrop...
Article
During lichenological explorations of tropical montane forests in Kenya, a remarkable new lichenicolous fungus was repeatedly found growing on thalli of the epiphytic tripartite cyanolichen Crocodia cf. clathrata . Molecular phylogenetic analyses placed the fungus within Gomphillaceae ( Ostropales , Lecanoromycetes), a family mainly of lichen-symbi...
Article
A diversity of filamentous microfungi was discovered from thallus surfaces of epiphytic lichens preserved in Bitterfeld and Baltic amber. We report seven distinct morphologies of dematiaceous hyphomycetes, some of which closely resemble species of the extant genera Sporidesmium , Taeniolella s. lat. and Taeniolina . Both the placement of the fungi...
Article
Fossil tree resins preserve a wide range of animals, plants, fungi and microorganisms in microscopic fidelity. Fossil organisms preserved in an individual piece of amber lived at the same time in Earth history and mostly even in the same habitat, but they were not necessarily parts of the same interacting community. Here, we report on an in situ pr...
Article
Ascomycetes specialised to live on hardened plant exudates occur worldwide, but the number of species so far described is relatively small (c.30). Particularly within the genus Chaenothecopsis (Ascomycota: Mycocaliciales), many species produce their ascomata on hardened but still relatively fresh outpourings of conifer resin or angiosperm exudate....
Article
Full-text available
The widespread cyanolichen genus Peltigera comprises many insufficiently known poorly delimited and/or undescribed species. Phylogenetic analysis of 252 Peltigera specimens from a wide range of habitat types in Estonia revealed 31 putative taxa (OTUs). Multivariate analysis revealed habitat-specific segregation between the Peltigera species along a...
Article
Full-text available
Conifers of the endemic species Araucaria humboldtensis on Mont Humboldt in New Caledonia exhibit extensive resin exudation. The resin flows of these threatened trees are here shown to be induced by two beetle species, which bore into branches and branchlets, leading to abundant outpouring of resin, which gradually solidifies into often drop-shaped...
Article
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The world’s sole ‘parasitic’ gymnosperm Parasitaxus usta (Podocarpaceae) is endemic to the island of Grande Terre, New Caledonia. It is a threatened species because of its limited geographic range and progressing habitat fragmentation. Here, we report a novel scale insect outbreak on a Parasitaxus sub-population from Monts Dzumac in the southern pa...
Article
Full-text available
Transplant studies can provide valuable information on the growth responses of epiphytic bryophytes and lichens to environmental factors. We studied the growth of six epiphyte species at three sites in moist Afromontane forests of Taita Hills, Kenya. With 558 pendant transplants, we documented the growth of four bryophytes and two lichens over 1 yr...
Article
Lichens are highly specialized symbioses between heterotrophic fungi and photoautotrophic green algae or cyanobacteria. The mycobionts of many lichens produce morphologically complex thalli to house their photobionts. Lichens play important roles in ecosystems and have been used as indicators of environmental change. Here we report the finding of 1...
Chapter
Filamentous cyanobacteria are important primary producers and N2 fixers in many terrestrial environments. As reduced nitrogen is often limiting, some thalloid liverworts (Marchantiophyta), hornworts (Anthocerophyta), the water fern Azolla (Salviniales), cycads (Cycadophyta), and the angiosperm Gunnera (Gunnerales) have evolved the ability to establ...
Article
Full-text available
Fungus-growing termites of the subfamily Macrotermitinae together with their highly specialized fungal symbionts (Termitomyces) are primary decomposers of dead plant matter in many African savanna ecosystems. The termites provide crucial ecosystem services also by modifying soil properties, translocating nutrients, and as important drivers of plant...
Article
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Beavers are ecosystem engineers that modify and maintain a range of special habitat types in boreal forests. They also produce large quantities of deadwood that provide substrate for many lignicolous organisms such as calicioid fungi (Ascomycota). We studied how calicioid diversity differed between boreal riparian forests with and without beaver ac...
Poster
Full-text available
Epiphytes comprise a significant component of biodiversity and biomass in tropical forests. They are ecologically important in intercepting and retaining moisture, providing habitat and food for invertebrates, and contributing fixed nitrogen into the ecosystem. Lichens are mutualistic symbioses between lichen-forming fungi (mycobionts) and algae an...
Article
A novel species of ascomycetes is described from resin of Araucaria humboldtensis on Mont Humboldt in New Caledonia. The fungus is placed in the new genus Resinogalea, with the species name R. humboldtensis. It has only been found growing on semi-hardened resin flows on branches of its endemic and endangered conifer host. The morphology and anatomy...
Article
Full-text available
The fossil record of lichens is scarce and many putative fossil lichens do not show an actual physiological relationship between mycobionts and photobionts or a typical habit, and are therefore disputed. Amber has preserved a huge variety of organisms in microscopic fidelity, and so the study of amber fossils is promising for elucidating the fossil...
Poster
Full-text available
Amber is fossilized resin of gymnosperm and angiosperm trees and it is famous for its lifelike preservation of arthropods, plant remains, and microorganisms. The fossil record of many lineages of fungi, plants, and arthropods is actually restricted to amber inclusions and even the preservation of soft-bodied microorganisms has cellular and ultrastr...
Article
Full-text available
We describe a diverse taphocoenosis in a piece of Mexican amber that includes two morphotypes assignable to the leafy liverwort family Lejeuneaceae, an angiosperm seed, a putative bud scale, dematiaceous hyphomycetes as well as dipteran and hymenopteran insects belonging to Phoridae (genera Megaselia, Puliciphora, and Apocephalus), Cecidomyiidae, P...
Article
Full-text available
Cyanolichens are obligate symbioses between fungi and cyanobacteria. In these associations the cyanobacterial symbiont can either be the sole photosynthetic partner or a secondary symbiont in addition to a primary green algal photobiont. Lichen-symbiotic cyanobacteria can provide both photosynthate and fixed nitrogen to their symbiotic partners and...
Article
Full-text available
Four new resinicolous species of Chaenothecopsis are described from China: Chaenothecopsis perforata from exudate of Rhus chinensis (Anacardiaceae), C. pallida from exudate of Ailanthus altissima (Simaroubaceae), C. resinophila from exudate of Kalopanax septemlobus (Araliaceae) and C. hunanensis from resin of Pinus massoniana (Pinaceae). All the ne...