Small Thalli Research Articles

R2R3-MYB transcription factor GEMMA CUP-ASSOCIATED MYB1 mediates the cytokinin signal to achieve proper organ development in Marchantia polymorpha

Cytokinin, a plant hormone, plays essential roles in organ growth and development. The type-B response regulator-mediated cytokinin signaling is repressed by type-A response regulators and is conserved in the liverwort Marchantia polymorpha. Its signal coordinates the development of diverse organs on the thallus body, such as the gemma cup, rhizoid, and air pores. Here we report that the type-B response regulator MpRRB upregulates the expression of the R2R3-MYB transcription factor GEMMA CUP-ASSOCIATED MYB1 (MpGCAM1) in M. polymorpha. Whereas both Mpgcam1 and Mprrb knockout mutants exhibited defects in gemma cup formation, the Mpgcam1 Mprra double mutant, in which cytokinin signaling is activated due to the lack of type-A response regulator, also formed no gemma cups. This suggests that MpGCAM1 functions downstream of cytokinin signaling. Inducible overexpression of MpGCAM1 produced undifferentiated cell clumps on the thalli of both wild-type and Mprrb. However, smaller thalli were formed in Mprrb compared to the wild-type after the cessation of overexpression. These results suggest that cytokinin signaling promotes gemma cup formation and cellular reprogramming through MpGCAM1, while cytokinin signals also participate in activating cell division during thallus development.

Gelidiorariphycus gen. nov. (Gelidiales, Rhodophyta): a rare genus found in the Americas

ABSTRACT DNA sequence analyses have demonstrated that Gelidium as currently circumscribed is not monophyletic and has three distinctive lineages: Gelidium sensu stricto that includes the generitype Gelidium corneum, the Capreolia group, and another lineage that includes two distinct clades formed by species from the eastern Pacific and western Atlantic Oceans. A new genus of small gelidioid algae, Gelidiorariphycus, is described to accommodate one of the clades in this latter lineage. Four species (Gelidiorariphycus loratus, G. gahunbooi, G. stipitatus and G. sungminbooi) segregated into this genus in single- and multi-gene phylogenies. Gelidiorariphycus is sister to a clade formed by an unidentified eastern Pacific species and Gelidium lingulatum. These clades are closely related to a clade formed by Gelidiophycus and the Capreolia group. All four Gelidiorariphycus species were morphologically similar with small thalli that have simple and distally flattened erect axes. Fertile tetrasporophytes were found to have sori with sterile margins that are acutely tapered, which may be morphologically distinctive, but determining this requires additional study. These species were rare, with only one or two samples of each collected despite Gelidiales surveys having been done in the areas where they are known. They were mainly found growing on shallow subtidal rocky shores, but a G. gahunbooi specimen was also collected at more than 30 m depth. Their small size and preference for subtidal habitats may explain the small number of specimens collected. The recognition of this new genus is a further step in the establishment of a natural classification system for genera within the Gelidiaceae.

Gelidium rosulatum (Gelidiales, Rhodophyta), a new species of subtidal marine algae from Korea

ABSTRACT Gelidium rosulatum, a new species from the subtidal zone in eastern Korea, is described on the basis of morphological observations and molecular analyses. Phylogenies of plastid rbcL and mitochondrial cox1 markers revealed the distinctness of the new species, which was closely related to other East Asian species and G. chilense. Gelidium rosulatum is distinguished by a small thallus (up to 0.8 cm) that forms rosette turfs, leaf-like branchlets arising spirally along the erect axis, abundant rhizines in the medulla, cylindrical tetrasporangial sori without sterile margins, and rhomboid bilocular cystocarps borne on the apical parts of branchlets. The diversity of Korean Gelidium is now updated to 19 species, but further surveys of little explored areas and studies of dubious reports may reveal additional undescribed species.

Five New Species of the Lichen-Forming Fungal Genus Peltula from China.

The genus Peltula is an important cyanobacterial lichen group. We performed a taxonomic study on the Peltula from China using phylogenetic analysis based on three gene loci (ITS, nuSSU, nuLSU) together with additional species delimitation analyses by ABGD, bPTP and GMYC approaches and the phenotypic characteristics. Five new species (Peltula lobulata, P. polycarpa, P. polyphylla, P. pseudoboletiformis and P. submarginata) were found and described. Peltula lobulata is diagnostic in its small thallus with plenty of lobules, rolled down and irregularly lobed margins, and uneven cracked surfaces. Peltula polycarpa has convex and rolled down lobes and numerous apothecia with a thalloid rim covering the whole lobe, and it can be distinguished from fertile P. farinosa (southern Switzerland) by a bright olive-green and epruinose surface, and the absence of isidia. Peltula polyphylla is differentiated from any other known Peltula species by a very small polyphyllous thallus composed of abundant olive-brown to olive-black small lobes growing tightly and sometimes anastomosing and attaching to the substrate by a large and strong umbilical cluster. Peltula submarginata is similar to P. marginata but differs in the presence of encircled epinecral and algae layers, and the absence of a lower cortex. Peltula pseudoboletiformis is different from the similar species P. boletiformis in greener lobes, more yellow–green umbilici and certain phylogenetic differences. Moreover, a key to the species of Peltula in China is also provided here.

A New Species of Kumanoa (Batrachospermales, Rhodophyta) from Baiyun Mountain, Guangdong, China

Kumanoa belonging to the order Batrachospermales is the most species-rich and widely distributed genus of freshwater red algae in China. In this study, a new Kumanoa species is described and illustrated from Baiyun Mountain, Guangdong, China, based on morphological observations and phylogenetic analysis. Kumanoa baiyunensis sp. nov is morphologically distinguished from other species by presenting a small habit (0.5–1 cm tall) with abundant branching in upper part of the thallus; carposporophytes spherical and one per whorl; club-shaped trichogynes with distinct stalk; spermatangia sparse and single-grown, terminal on primary fascicles. Phylogenetic analysis based on the concatenated rbcL+COI-5P+UPA alignment places Kumanoa baiyunensis in a well-supported clade (98/0.96, bootstrap proportion/posterior probability) sister to K. faroensis (from USA) and K. spermatiophora (from Hawaii) with high divergence (rbcL: 4.9%–5.0%, COI-5P: 10.1%–10.5%, UPA: 2.3%). In addition, K. baiyunensis can be easily distinguished from ten Kumanoa species reported in China through morphological features such as small thallus size, abundant branching in upper parts of the thallus, and spermatangia sparse, single-grown, and terminal on primary fascicles. The description of this new species expands the diversity of genus Kumanoa in the world.

Siphula paramensis V. Marcano & L. Castillo (Icmadophilaceae, Lichenized Fungi), a new species from the high paramo in Venezuela

A new species of the genus Siphula is described from the Cordillera de Merida and Sierra La Culata in the Venezuelan Andes: Siphula paramensis V. Marcano & L. Castillo sp. nov. This species closely resembles Siphula subsimplex V. Marcano from the Guayana Highlands. Siphula paramensis differs by its very small thallus, obovoid or globuliform lobes, ochre-coloured, yellowish or whitish gray (in older thalli) surface, rugose, rounded and entire apices having usually reticulated lines, less thick cortex and shorter rhizines; the thalli are K–, C+ yellow, and P+ yellow in the cortex, and contain baeomycesic and squamatic acids. This is the Siphula species that grows at the highest altitude in Venezuela. It is considered to be endemic to the Venezuelan Andes.

Effect of Isolation Conditions on Diversity of Endolichenic Fungal Communities from a Foliose Lichen, Parmotrema tinctorum.

Endolichenic fungi (ELF) are emerging novel bioresources because their diverse secondary metabolites have a wide range of biological activities. Metagenomic analysis of lichen thalli demonstrated that the conventional isolation method of ELF covers a very limited range of ELF, and the development of an advanced isolation method is needed. The influence of four variables were investigated in this study to determine the suitable conditions for the isolation of more diverse ELF from a radially growing foliose lichen, Parmotrema tinctorum. Four variables were tested: age of the thallus, severity of surface-sterilization of the thallus, size of a thallus fragment for the inoculation, and nutrient requirement. In total, 104 species (1885 strains) of ELF were isolated from the five individual thalli of P. tinctorum collected at five different places. Most of the ELF isolates belong to Sordariomycetes. Because each part of lichen thallus (of different age) has unique ELF species, the whole thallus of the foliose lichen is needed to isolate diverse ELF. Moderate sterilization is appropriate for the isolation of diverse ELF. Inoculation of small fragment (1 mm2) of lichen thallus resulted in the isolation of highest diversity of ELF species compared to larger fragments (100 and 25 mm2). Moreover, ELF species isolated from the small thallus fragments covered all ELF taxa detected from the medium and the large fragments in this study. The use of two media—Bold’s basal medium (nutrient poor) and potato dextrose agar (nutrient rich)—supported the isolation of diverse ELF. Among the tested variables, size of thallus fragment more significantly influenced the isolation of diverse ELF than other three factors. Species composition and richness of ELF communities from different lichen thalli differed from each other in this study.

A revision of Hypotrachyna subgenus Parmelinopsis (Parmeliaceae) in eastern North America

A taxonomic revision of Hypotrachyna subgenus Parmelinopsis in eastern North America is presented based on molecular phylogenetic analyses of ITS and mtSSU data, extensive field observation and analyses of chemical and morphological data. Each species is described, illustrated with photographs, and the distribution in the region is mapped. An identification key is also presented. Eleven species are recognized: H. afrorevoluta, H. appalachensis, H. britannica, H. cryptochlora, H. horrescens, H. kauffmaniana, H. minarum, H. mcmulliniana, H. revoluta, H. showmanii and H. spumosa. Extensive discussion of prior studies is provided, particularly with respect to the delimitation of H. afrorevoluta and H. revoluta. Hypotrachyna kauffmaniana is described from the central and southern Appalachian Mountains and separated from H. afrorevoluta and H. revoluta by its ascending secondary lobes and pustulose soralia that are primarily confined to the secondary lobes. Hypotrachyna horrescens is shown to correspond to a taxon with narrow lobed, small thalli with ciliate isidia. Hypotrachyna mcmulliniana is described from material collected throughout southeastern North America that is chemically identical to H. horrescens but differs in having larger thalli and sparsely ciliate isidia. Hypotrachyna appalachensis is described to accommodate material previously referred to H. minarum but that differs in the production of 4,5-di-O-methylhiascic acid in high concentrations (vs. absent or present as a trace in H. minarum). Hypotrachyna britannica is reported for the first time from North America.

Growth Curve of the Crustose Lichen Ochrolechia parella Obtained from Marginal Growth Rings

Thalli of the crustose lichen Ochrolechia parella have marginal ‘growth rings’ enabling rapid estimation of radial growth rates (RaGR) over successive years. I obtained a growth curve, viz. changes in RaGR with thallus size, from rings of two populations of O. parella and in one population, and compared the growth curves obtained from rings and by measuring growth directly. Both methods revealed that RaGR in O. parella increased with thallus size in smaller thalli becoming more constant in larger thalli, a growth curve similar to that of foliose and placodioid species rather than crustose lichens such as Rhizocarpon geographicum in which growth declines in larger thalli. In O. parella the marginal zone comprises a layer of confluent areolae which may be better able to support and maintain a more constant growth rate compared with R. geographicum in which the marginal areolae are often isolated and scattered.

Small Parmeliaceae (liquenized Ascomycota) of Ilhabela State Park and nearby areas, São Paulo state, Brazil

Abstract A survey of lichens at Ilhabela State Park and nearby areas in São Sebastião Island revealed the occurrence of 12 taxa belonging to six genera of small foliose Parmeliaceae, which are characterized by usually small thalli (hardly > 10 cm in diameter) with narrow lobes or laciniae less than 1 cm wide. Comments are provided for the species registered.

Cultivation of early life history stages of Porphyra dioica from the British Isles

Bladed Bangiales of the genus Porphyra/Pyropia are highly valuable red algae and extensively farmed in South East Asia. Interest is rising in cultivating species local to the North East Atlantic but the control of the heteromorphic life cycle of native species remains difficult as previous studies reported high inter- and intraspecific variability in required cultivation conditions. Here, working with Porphyra dioica from a UK source population, we conducted a series of experiments investigating the influence of substrate, temperature, photoperiod and light intensity on the development of early life history stages (conchocelis (filamentous sporophyte) and young thalli (gametophyte)). Special focus was the influence of temperature and photoperiod on mature conchocelis to induce a conchospore mass release—the current bottleneck of European Porphyra cultivation. Sporophytes grew largest on an oyster shell substrate and under long day conditions at 18 °C. A decrease in temperature from 18 to 9 °C initiated a mass conchospore release (498 ± 146 spores mL−1) from a P. dioica conchocelis culture grown in suspension. Released conchospores germinated into small thalli on nylon ropes, with best growth (7.2 ± 0.9% day−1) at low temperatures of 9 °C. Conchospore germination increased with decreasing light intensity but germination success was generally very low (< 5%), indicating the cultivation protocol needs further improvement. Our results reflect the adaptation of P. diocia to seasonal environmental conditions in temperate regions and the importance of these conditions for the successful cultivation. We are the first to describe a mass conchospore release for P. diocia growing in suspension which has important implications for commercial production.

Updating Ceramium (Rhodophyta, Ceramiales) biodiversity in the North Adriatic Sea (Mediterranean): Ceramium rothianum sp. nov. and rediscovery of three forgotten species

ABSTRACTThe cosmopolitan genus Ceramium Roth (Ceramiaceae), with over 200 currently accepted species, is one of the largest in the Rhodophyta. The genus is characterized by cylindrical or slightly compressed thalli, with axial cells incompletely to completely covered by cortical cells, alternate to pseudo-dichotomous branching and straight to inrolled apices. Despite recent studies, the nomenclature and taxonomy of this genus are still very problematic, linked to the high degree of variation in morphological characters, small thallus sizes, epiphytic habit and the existence of cryptic species. The Mediterranean Sea is reported to have a particularly high diversity of Ceramium species: the North Adriatic Sea, in particular Venice and nearby coasts, was a favourite classical collecting area from where several species were described. In this study we characterize Ceramium sampled from transitional waters of the Venice Lagoon (Italy) by molecular and morphological approaches. Through phylogenetic analyses, using the plastid ribulose-1,5-bisphosphate carboxylase/oxygenase gene (rbcL) as molecular marker, we identify six distinct taxonomic entities, of which four represent taxa not currently recognized in the Venice Lagoon or the wider Mediterranean Sea. One of these is the poorly known species Ceramium connivens Zanardini, which is non-spiny and fully corticated when mature with short naked internodes developing in older axes. Two entities with erect partially corticated thalli without spines, probably misidentified up to now as Ceramium diaphanum (Lightfoot) Roth, correspond to the new species Ceramium rothianum Wolf et al. and to the forgotten species Ceramium nodosum (Kützing) A.W. Griffiths & Harvey. The last entity, characterized by prostrate axes giving rise to narrow erect incompletely corticated, non-spiny axes, is identified as the rare, poorly known species Ceramium incospicuum Zanardini.

Gracilaria phuquocensis sp. nov., a new flattened Gracilaria species (Gracilariales, Rhodophyta), previously recognized as G. mammillaris, from the southern coast of Vietnam

SUMMARYFlattened Gracilaria species are widely distributed along the coasts of the South China Sea with more than 20 species recorded. Within the South China Sea, Gracilaria mammillaris has only been reported from Vietnam, but this species is likely restricted to the western Atlantic. This study aimed to reevaluate the taxonomic status of Vietnamese specimens of ‘G. mammillaris’ using combined morphological and molecular data. Our data clearly indicated that Vietnamese specimens were morphologically and genetically distinct from authentic G. mammillaris from the western Atlantic, and also other described flat Gracilaria species. We, therefore, propose that specimens from Vietnam originally identified as G. mammillaris be designated as a new species, Gracilaria phuquocensis sp. nov. Morphologically, G. phuquocensis can be distinguished from other flat Gracilaria species by its small thallus size, narrower blades, many medullary layers, abundant basal nutritive filaments within mature cystocarps, and tetrasporangial nemathecium. Our rbcL sequence analyses showed that the new species was sister to Gracilaria rhodymenioides from Thailand, and these two species formed a clade with cylindrical Gracilaria species. Our study contributes to clarification of the taxonomic status of misidentified specimens attributed to the flattened Gracilaria species in the South China Sea.

Usnea jørgenseniana Bystr. &amp; Leśniewska sp. nova Usnea (subgen. Usnea, Parmeliaceae) in Sweden

&lt;p&gt;Usnea jørgenseniana Bystr. &amp;amp; Leśniewska sp. nova, an epixilic species of bushy Usnea (Parmeliaceae) in Sweden, is similar to U. hirta var. minutissima (Mer.) Bystr., but the similarity to U. hirta is apparent. U. jørgenseniana is not a species from the foveatae Mot. section. The lack of soralia and a very small thallus (0.3–2.0 cm) makes it difficult to locate U. jørgenseniana in the section Comosae Mot. It colonizes exceptionally unfavorable climatic conditions, a coprophilous species. Collected by G. Ohrstedt in 1937. Dozens of specimens from one position.&lt;/p&gt;

Genetic and morphological variations of the lichenized fungus Steinera intricata (Arctomiaceae, Lecanoromycetes) from southern South America to Antarctic Peninsula

Steinera (Arctomiaceae, Lecanoromycetes) is an Austral genus of lichenized fungi that form symbiotic associations with cyanobacteria, producing small and inconspicuous thalli. Most species of Steinera present a high degree of endemism restricted to sub-Antarctic islands except S. intricata which occurs from southern South America to the Antarctic Peninsula and presents remarkable phenotypic variation along its distribution range. In this study, an integrative approach was used to explore the extent of intraspecific diversity of S. intricata throughout its distribution. Morphological and anatomical descriptions and the phylogenetic analyses of three genomic regions were performed with specimens collected from seven Antarctic islands and in the Tierra del Fuego National Park (Argentina). Genetic data revealed species-level lineages are not associated with the differences observed in the thalli shape, which probably are related to distinct microhabitats and substrates as well as to the development stage. Molecular clock analyses estimated that S. intricata originated at about 0.24 Myr and that the diversification of the Antarctic lineages occurred at about 0.16 Myr. This study revealed that there is probably an unknown diversity of new members of Steinera in southern South America and that the evolutionary history of these cyanolichens may contribute to the understanding of the phylogeographic connections between members of the Austral-Antarctic flora.

High-light stress in wet and dry thalli of the endangered Mediterranean lichen Seirophora villosa (Ach.) Frödén: does size matter?

In the Mediterranean basin, coastal dune systems are a priority habitat for nature conservation. Seirophora villosa is strictly associated with undisturbed dune juniper formations and can be used as an indicator of the status of conservation. Light regime and water availability are generally the main ecological factors modified by habitat fragmentation that can be detrimental to the colonisation and survival of S. villosa populations in coastal dunes. This study aims to investigate how light regime and water availability affect individual specimens of S. villosa, by studying the relationship between photosynthetic activity and water content per thallus area in different sized S. villosa thalli and comparing susceptibility of hydrated and desiccated thalli to light stress. During dehydration, photosynthetic activity decreased, reaching low constant values in smaller thalli more quickly than in larger ones. During the exposure of dry thalli to high light, photoinhibition consistently occurred earlier in smaller specimens than in larger ones. Moreover, larger thalli that were kept dried recovered to pre-treatment values within 3 days, while smaller ones took 5 days to recover initial values. On the other hand, both large and small wet thalli were photoinhibited within 1 day and recovered to pre-treatment values within 4 and 6 days respectively. Our results showed that S. villosa thalli are susceptible to sudden increases in light exposure, especially in the case of small specimens, which after photoinhibition exhibited a reduced ability to recover. Habitat fragmentation therefore represents a significant threat to the species, particularly in dispersal and establishment phases.

Three new species and one new combination of Gypsoplaca (lichenized Ascomycota) from the Hengduan Mountains in China

Three new species are described as follows: Gypsoplaca alpina H. X. Shi and Li S. Wang, G. bullata H. X. Shi and Li S. Wang, and G. rosulata H. X. Shi, Li S. Wang, and Timdal sp. nov. Gypsoplaca alpina is characterized by a small thallus, upper cortex with very thick gelatinized layer, ascocarp warty with a cerebriform ridging, and by growing on soil in alpine meadows. Gypsoplaca bullata characterized by having bullate ascocarp, uneven to bullate thallus. Gypsoplaca rosulata is characterized by rosulate thallus and 4–6-spored asci. The new combination Gypsoplaca blastidiata (Zhurb) H. X. Shi and Li S. Wang comb. & stat. nov. is proposed. A phylogenetic tree is established, based on combined sequences of ITS and nrLSU, and all species formed monophyletic clades. Two main chemical compounds, brialmontin and sesterterpenes, are reported for the first time from Gypsoplaca by analysis of NMR and MS data. Triterpenoids are absent in Chinese Gypsoplaca specimens.

New Record of a Marine Algal Species, Ahnfeltiopsis linearis (Phyllophoraceae, Gigartinales), in Korea

A marine algal species belonging to Gigartinales was collected from Geoje, Korea. This shares the generic features of Ahnfeltiopsis, such as multiaxial thalli with a compact and pseudoparenchymatous medulla, densely cytoplasmic secondary medullary cells around immersed cystocarps with a carpostome, and is distinct from similar species within the genus by a combined feature of small (up to 4 cm tall) and tuft thalli, compressed to subcompressed branches except for ultimate branchlets and base of main axes, cartilaginous in texture, dichotomous branches, rarely produced proliferations, absence of hypha-like filament in the medulla and internal cystocarps with a carpostome. In phylogenetic tree based on rbcL sequence, the Korean species nests in the same clade with Ahnfeltiopsis linearis. The genetic distance between both sequences within the clade was 1.5%, considered to be within the intra-species range for the genus. This morphological and molecular evidence confirms the Korean alga to be identified as A. linearis originally described from California. This is the first record of A. linearis in Korea.

Changes in drag and drag coefficient on small Sargassum horneri (Turner) C. Agardh individuals

Sargassum horneri (Turner) C. Agardh is used to restore, create, and recreate seaweed beds along the coastlines of East Asia. Drag produced by waves is a bulk force that can detach thalli from substrata during the early growth stages from substrata. In this study we measured drag forces on small S. horneri thalli (10–40cm long). Unidirectional steady flow was controlled from 20 to 130cms−1 in increments of 10cms−1 in a recirculating water tank. Drag force on individuals ranged from ∼0.3N to ∼3N. Drag (Fdrag) and water velocity (U) produced the following exponential empirical approximations: Fdrag=0.0168×U0.8925. The drag coefficient (Cd) was plotted as a function of Reynolds number (Re) as follows: Cd=4744.7×Re−0.93. Cd converged to 0.037 at Re of 105−6 suggesting that small thalli exhibit optimal morphological adaptations to withstand high current speeds.

High morpho‐anatomical variability in Halimeda macroloba (Bryopsidales, Chlorophyta) in Thai waters

SUMMARYHalimeda macroloba is a common widespread and morphologically variable species in the Indo‐Pacific Ocean. A series of morphometric data (16 morphological and 46 anatomical variables) and the chloroplast‐encoded tuf A gene were examined to explore the morphological and genetic variations within the species and to better determine species boundaries in H. macroloba in Thai waters. Moreover, the environmental conditions, which may affect morphological variations in H. macroloba, especially of Haplotype I were examined. Our results showed that H. macroloba has more morpho‐anatomical variability and broader species boundaries than previously thought in several characters: holdfast type, segment shape and size, node height with differences in pore size, the presence of two additional patterns of peripheral utricle as seen in surface view, and additional layers of utricles (up to seven layers). Additionally, two new variable characteristics have been reported for the first time, i.e. shape and margin of peripheral utricles. Water depth and light correlated with thallus morphology, larger thalli and segments with a greater number of utricle layers were associated with subtidal plants, while smaller thalli and segments were found in the intertidal or high light intensity areas. The high plasticity of this species may explain why in the Indo‐Pacific Ocean this species is common and dominant.