Magdalena Dudek

Spiranthoid orchids, a diverse group with both wide ecological demand and high morphological variability, remain particularly challenging in terms of classification. Despite phylogenetic analyses indicating monophyly of the tribe Spiranthinae, inconsistencies between morphological and genetic data, as well as conflicts between nuclear and plastid markers, have hindered the establishment of clear taxonomic boundaries. Seed morphology, which has been successfully applied in plant systematics, remains understudied in this group. Here, we investigated seed morphology and surface ultrastructure in 67 species of spiranthoid orchids based on both quantitative biometric measurements and qualitative micromorphological characters (scanning electron microscopy), with trait variation evaluated using multivariate statistical analyses interpreted in a phylogenetic context. Seed morphology in spiranthoid orchids is highly variable and shows no consistent correlation with phylogeny, distribution, environment, or plant size. Only Myrosmodes nubigenum exhibits a clear distinctiveness, likely due to its isolated evolutionary position and high-Andean habitat. While seed traits can aid in diagnosing certain taxa, their utility for infra-tribal classification is limited. Broader studies integrating morphological, molecular, and ecological data are needed to clarify the evolutionary drivers of seed diversity in this group.

Background: Dendrobium is a large genus within the Orchidaceae family, containing over 1,600 species. Most are sympodial epiphytes. These species are distributed throughout southern, eastern, and southeastern Asia, the Pacific Islands, Australia, New Guinea, and New Zealand. Infrageneric classification of this group is challenging, largely because of the large number of taxa, the wide geographic range, and the considerable morphological diversity. The primary objective of our research was to analyze the genus Dendrobium (focusing primarily on the nominal section) using DNA sequences and to integrate these findings with morphological data. Results: UPGMA morphological analysis and SIMPER analysis, considering 14 characters, showed that characters such as the placement of the inflorescence, the pseudobulbs from which the inflorescence grows, the surface of the lip, and the number of lobes on the lip are the distinguishing characters of the taxa within Dendrobium sensu lato.The nominal section, Stachyobium, and Formosae (species-rich) are more morphologically variable and exhibit a wide range of variability, in contrast to sections with fewer species. The reconstruction of the ancestral states of Dendrobium sensu lato showed that most of the characters examined arose independently several times during evolution. The only exception is dorsiventrally compressed leaves, a character that arose only once. In addition, the nominal section is not monophyletic and is not entirely consistent with morphology, and species of Holochrysa, Breviflores and Stuposa are closely related. Conclusion: We conclude that convergent evolution likely occurred among Dendrobium sensu lato representatives, and that many floral traits may have resulted from adaptations to pollinators. This has led to numerous classification problems within the genus. We have not received a clear answer to the question of how to classify species across the genus. Therefore, in this study, we focused primarily on the nominal section.

Dendrobium is a large group of Orchidaceae, counting more than 1,100 species, whose classification, both within the genus and individual sections, is not straightforward. Therefore, the aim of our study was to perform phylogenetic analyses for representatives of a nominal section of Dendrobium and to test the usefulness of a low-copy nuclear gene encoding a xanthine dehydrogenase protein for reconstructing phylogeny. We also wish to compare the utility of two nuclear markers, Xdh and ITS. To realize this, we analyzed the diversity of the two markers and the reliability of the resulting trees. Our results indicate that the nuclear ITS region shows higher variability and clade credibility in trees, in closely related species, and between sections than the low-copy nuclear gene. Xdh may be more reliable at higher taxonomic levels, but confirmation of this requires further research.

To solve the taxonomic affiliation of Bulbophyllum physometrum, the only known species of the Bulbophyllym sect. Physometra (Orchidaceae, Epidendroideae), we conducted phylogenetic analyses based on nuclear markers, i.e., ITS and the low-copy gene Xdh, and the plastid region matK. We used Asian Bulbophyllum taxa, with a special focus on species from the sections Lemniscata and Blepharistes, i.e., the only Asian sections of this genus with bifoliate pseudobulbs, as in B. physometrum. Unexpectedly, the results of molecular phylogenetic analyses showed that B. physometrum is most probably more related to the representatives of the sections Hirtula and Sestochilos than Blepharistes or Lemniscata.

Guatemala is recognized for its diverse and rich flora and fauna. It is estimated that over 1200 orchid species, classified in 223 genera, are known to occur in this rather small, yet megadiverse country. While studying the diversity of this plant group in the department of Baja Verapaz, we found individuals that clearly belonged to the genus Schiedeella, but whose features did not fit any previously known species. At that time, nine terrestrial taxon representatives were known to occur in Guatemala. We conducted the morphological analysis in accordance with the standard procedures of classical taxonomy. For phylogenetic reconstruction, 59 sequences of the ITS region and 48 of the trnL-trnF marker were applied. The topology of trees was obtained based on the Bayesian inference. Schiedeella bajaverapacensis was described and illustrated based on morphological evidence, and its taxonomic position was confirmed by phylogenetic analyses. The new entity is the 10th Schiedeella representative known from Guatemala.

Dendrobium is one of the most species-rich genera of the Paleotropical orchids. It embraces more than 1000 species, most of which are epiphytes. The strong variation in floral characters causes many identification difficulties within this genus. One of the key structures, often sufficient in identification on a species level, is the labellum, which in many species of Dendrobium possesses a thickened callus and various types of trichomes and papillae. The aim of this study is to identify and describe the structures present on the labellum surface of the analyzed species, determine their distribution and density, as well as to check whether the obtained data have taxonomic value. In this paper, we present the results of a micromorphological study on the labellum of 21 species of Dendrobium, representing 13 sections, using scanning electron microscopy (SEM). Our studies revealed the presence of both uni- and multicellular structures on the surface of the labellum. We observed three types of trichomes (conical, cylindrical, ellipsoidal) and three types of papillae (conical, cylindrical, semicircular). Neither trichomes nor papillae were recorded for five species. In addition, we made diagrams showing the distribution and density of structures on the labellum. Based on the micromorphological results combined with the phylogenetic tree performed, we suggest that the presence/absence of labellum structures does not necessarily reflect the phylogenetic relationship and might be misleading, as in some cases, they arise due to convergence.

Background. Pachygenium embraces a group of terrestrial species formerly placed in Pelexia sensu lato. The genus currently comprises some 60 species, most of which are known from the southern parts of Brazil and Paraguay, with few species distributed in the Andean countries???only four species have been recorded from Argentina so far. In Jujuy Province, Argentina a new species of Pachygenium was found during our fieldwork. The aim of this article was to provide morphological and molecular evidence for its membership in this genus. Methods. Materials from specimens were collected in the field and examined by classical taxonomic and molecular biological techniques, e.g., PCR and sequencing DNA. Phylogenetic reconstruction was performed by maximum-likelihood and Bayesian inference. Results. Pachygenium laurense from Argentina is described and illustrated based on morphological evidence and its taxonomic position was confirmed by phylogenetic analyses. A new combination for Pachygenium gutturosa is also proposed. A key for identification is provided for the Pachygenium species occurring in Argentina. Conclusion. Pachygenium laurense is the fifth species of the genus recorded from Argentina.

The results of a revision of the orchid genus Andinia are presented. The proposed classification is based on outcomes of morphological and molecular studies. Additionally, the similarity of the climatic niches occupied by representatives of the Andinia-complex was calculated and visualized. The highest number of Andinia representatives is found in the Eastern Cordillera real montane forests, while Neooreophilus species are found in two ecoregions—the Eastern Cordillera real montane forests, and the Northwestern Andes. According to the level of endemism, a very unique orchid flora was noted in the Guajira–Barranquilla xeric scrub ecoregion, as well as in the Isthmian-Pacific and the Ucayali moist forests, where single endemic species occur. In the proposed classification, nine genera are recognized within the Andinia-complex, three of which (Xenosiella, Chicalia, and Minuscula) are described in this paper. A key to the identification of all genera is provided. Additionally, sections Amplectentes and Bilamellatae of Neooreophilus are elevated to the subgeneric rank, and subgenus Aenigma is here considered as a separate genus. A complete list of representatives of each taxon is provided, and new combinations are proposed accordingly. A new species of Neooreophilus from Colombia is described.

Despite the clear circumscription of tribe Sobralieae (Orchidaceae), its internal relationships are still dubious. The recently delimited genus Brasolia, based on previous Sobralia species, is now assumed to be paraphyletic, with a third genus, Elleanthus, nested in it. The morphology of these three genera is significantly different, indicating the necessity of new data for a better genera delimitation. Though morphology and molecular data are available, cytogenetics data for Sobralieae is restricted to two Sobralia and one Elleanthus species. Aiming to evaluate the potential of cytogenetic data for Brasolia-Elleanthus-Sobralia genera delimitation, we present chromosome number and genome size data for 21 and 20 species, respectively, and used such data to infer the pattern of karyotype evolution in these genera. The analysis allowed us to infer x = 24 as the base chromosome number and genome size of average 1C-value of 5.0 pg for the common ancestor of Brasolia-Elleanthus-Sobralia. The recurrent descending dysploidy in Sobralieae and the punctual genome upsize suggest a recent diversification in Sobralieae but did not allow differing between Brasolia and Sobralia. However, the basal position of tribe Sobralieae in the subfamily Epidendroideae makes this tribe of interest to further studies clarifying the internal delimitation and pattern of karyotype evolution.

The lectotypification of six names of species, originally described as Evelyna Lind. (Orchidaceae), based on collections of Jean Jules Linden from locations that are currently in Venezuela and Colombia, is proposed. We also provide the number and location of duplicates of the type material.