Morphological Delimitation Research Articles

“Picking up signals” in male genital morphospace and integrating phylogenomics to delimit Neotropical Nylanderia Emery species (Hymenoptera: Formicidae)

Abstract Genital morphology, a cornerstone in taxonomy that predates Linnaeus’s Systema Naturae, is vital for species delimitation. However, the widely accepted paradigm that genitalia are taxonomically informative lacks robust testing between closely related species, and supporting evidence is often limited to taxonomic literature in which genitalia are assumed a priori to be species-specific. The cosmopolitan ant genus Nylanderia Emery includes 123 described species, with most in the Neotropics still undescribed. Workers are often morphologically cryptic, and males are rare in collections but required for morphological delimitation. Using Ultraconserved Elements (UCEs) from 236 samples, including 53 Neotropical Nylanderia species, we reconstructed a phylogenetic framework to compare the genitalia (gonopods) of males collected alongside workers. We used geometric morphometrics on images of slide-mounted genitalia from 16 species and nano-CT scans of Nylanderia fulva (Mayr) and Nylanderia pubens (Forel) genital capsules and interpreted results considering phylogeny under maximum likelihood and the multispecies coalescent. We found strong morphological and molecular support for 2 distantly related American clades, identifiable by gonopod shape, with significant differences observed among most species. Three previously reported COI clades of N. fulva were not supported as monophyletic, nor were their gonopods significantly different. However, N. pubens was supported as distinct by all phylogenetic and 3DGM results. Our findings emphasize the importance of male genitalia for delimiting species boundaries and revising Neotropical Nylanderia. Given their importance, particularly in morphologically cryptic taxa, we recommend a greater focus on linking male and worker phenotypes, which can be facilitated through comprehensive nest series collection.

An integrative delimitation of the species boundaries within one hornbeam species complex (Betulaceae: Carpinus)

AbstractBoth hybridization and intraspecific morphological variation across environmental gradients complicate species delineation. We aimed to discern both possibilities that may blur species boundaries in the Carpinus viminea–Carpinus laxiflora–Carpinus londoniana species complex. We conducted statistical analyses on 535 specimens encompassing the entire distribution of this species complex to identify phenotypic clusters. Additionally, we analyzed genetic divergence and probable hybridization between clusters using 76 individuals from 37 populations. Based on phenotypic and genetic clusters, we tentatively recognized four species: C. viminea, C. fargesii, C. laxiflora, and C. londoniana. Except for rare overlapping distributions between C. fargesii and C. londoniana, the redefined four species are mostly allopatric to each another based on their distributions. The morphological delimitation, species boundary and distribution of each species differ distinctly from past taxonomic treatments. For example, specimens previously identified under C. viminea, in fact, belong to three different species. Hybrids between C. fargesii and C. londoniana exhibit morphological traits similar to C. viminea, thereby contributing to difficulties in determining species boundaries and outlining species distributions. These findings suggest that local selection and geographical isolation may together have promoted both phenotypic and genetic divergences within this species complex. However, interspecific hybridization blurs species boundaries by producing hybrids with phenotypic similarity in addition to intraspecific variation. This study emphasizes the importance of statistical analyses of population‐level morphological and genetic variations across major distributional ranges for an integrative delimitation of species boundaries and the identification of hybridization and hybrids.

Stop black and white thinking: Russula subgenus Compactae (Russulaceae, Russulales) in Europe revised.

Russula subgenus Compactae is a group of ectomycorrhizal basidiomycetes, usually with large pileate fruitbodies. European members of the group are characterised by the absence of bright colours on the surfaces of their pilei, the context turning grey to black after cutting, the abundance of short lamellulae in the hymenophore, and spores with an inamyloid suprahilar spot and with low reticulate ornamentation. Our multi-locus phylogenetic study confirmed that this morphological delimitation corresponds to a well-supported clade. Within this clade, 16 species are recognised in Europe, of which five belong to the R. albonigra lineage and were described in a previous study, while eleven are fully described in this study. The application of the names R. acrifolia, R. adusta, R. anthracina, R. atramentosa, R. densissima, R. nigricans and R. roseonigra is based on the position of sequences retrieved from types or authentic material. Based on type sequences, R. fuliginosa is synonymised with R. anthracina and two varieties of R. anthracina are considered synonyms of R. atramentosa. The application of the name R. densifolia is based on a morphological match with the traditional species interpretation and the neotype specimen. Three species are described as new, R. marxmuelleriana sp. nov., R. picrophylla sp. nov. and R. thuringiaca sp. nov. This study recognises three major lineages and two species with isolated positions within the European Compactae and a morphological barcode was assigned to the species using an analysis of 23 selected characters. A search of publicly available sequences from the UNITE database revealed that the majority of species are host tree generalists and widely distributed in temperate and Mediterranean areas of Europe. Russula adusta is the only species so far proven to form ectomycorrhiza exclusively with conifers. Citation: De Lange R, Kleine J, Hampe F, et al. 2023. Stop black and white thinking: Russula subgenus Compactae (Russulaceae, Russulales) in Europe revised. Persoonia 51: 152-193. doi: 10.3767/persoonia.2023.51.04.

The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam

A synopsis of the orchid genus Didymoplexiella is presented for Cambodia, Laos and Vietnam. Uncertainties in morphological delimitation of the species of Didymoplexiella are addressed in the context of the new data on variation of labellum structure; re-identification of a considerable number of specimens is performed in accordance with the current views. Three species are recognised in the study area. Of them, D. laosensis is endemic to Laos and Vietnam; D. ornata is known from Vietnam and also widely distributed in Malesia; and D. siamensis inhabits all three countries of Eastern Indochina and also Thailand, Japan, China and Taiwan. Didymoplexiella laosensis is newly recorded for Vietnam, whereas D. trichechus is excluded from the known flora of Eastern Indochina, and D. ornata is excluded from the flora of Laos. Typification of D. siamensis is revised. For each species, the type, synonyms (where applicable), citations of relevant regional taxonomic publications, brief taxonomic notes, data on ecology, phenology, distribution and IUCN preliminary assessment are provided. The geographical distribution of the species of Didymoplexiella in Cambodia, Laos and Vietnam is shown on a map. A key for the identification of D. laosensis, D. ornata, D. siamensis and D. trichechus is presented.

Ganoderma from Cuba: an approach to some species based on morphology and phylogenetic analyses

Abstract Ganoderma is a genus of wood-decaying polypores fungi with several species, in which morphological delimitation has been challenging due to its large plasticity. Knowledge of the taxonomic diversity of Ganoderma in Cuba remains incomplete. Here, we identified some species, mainly laccate, of Ganoderma present in Cuba based on morphological and phylogenetic data and investigated their relationships with other species. Type specimens, recently collected materials, herbarium specimens and in vitro cultures were studied to delimit morphological species. The phylogenetic affinities of ten species were inferred based on multilocus (ITS rDNA, rpb2, tef1-α) DNA sequences to delimit phylogenetic species. In this work, 14 species of Ganoderma were recognized in Cuba, of which G. amazonense, G. curtisii, G. dussii and G. multiplicatum are reported for the first time. Ganoderma rodriguezii sp. nov. is described as a novel species. We confirmed G. amazonense is a non-laccate species although it is phylogenetically affine to laccate species. An identification key for studied species, nomenclatural information, updated descriptions and geographical distributions are presented. The lectotypification in second step of G. perzonatum, G. pulverulentum and G. zonatum was made here. To correctly interpret G. perzonatum, recent collections, including live strains from the type locality, are described. We confirm G. lucidum is not present in Cuba, despite previous records from the country.

Geometric Morphometric Analysis of Genus Chaetocnema (Coleoptera: Chrysomelidae: Alticini) with Insights on Its Subgenera Classification and Morphological Diversity

In taxonomy, qualitative methods are commonly used to analyze morphological characters, which can lead to dramatic changes in higher taxa. Geometric morphometrics (GM) has proven to be useful for discriminating species in various taxonomy groups. However, the application of geometric morphometrics in supraspecies classification is relatively scarce. In this study, we tested the controversial two subgenera classification of Chaetocnema with geometric morphometrics; a total of 203 Chaetocnema species representing 50% of all known species from around the world were selected for the analysis. We analyzed the shape of the pronotum, elytron, head, aedeagus, and spermatheca. The results showed that the two traditional subgenera distinctly differed from each other; therefore, we propose using two subgenera arrangements to facilitate the understanding and taxonomy of the Chaetocnema species (especially in the Oriental, Palearctic, and Nearctic regions). Additionally, the morphological diversity of the abovementioned structures of Chaetocnema was analyzed, and it was found that the highest morphological diversity was in the spermatheca, which was greater than that in the aedeagus. Our research demonstrated that GM could be useful for detecting morphological delimitation of the supraspecies taxa. It also showed that GM methods are applicable to insects as small as 2 mm in body size.

Reassessment of morphological species delimitations in the Cyperus margaritaceus-niveus complex using morphometrics

Background and aims – The Cyperus margaritaceus-niveus complex is a group of ten tropical species from sub-Saharan Africa and Madagascar: C. karlschumannii, C. kibweanus, C. ledermannii, C. margaritaceus, C. niveus, C. nduru, C. obtusiflorus, C. somaliensis, C. sphaerocephalus, and C. tisserantii. They are characterised by a capitate head of white-yellow spikelets and modified culm bases and recent molecular analysis puts them in a distinct clade. The group lacks a modern taxonomic revision, and the taxa described in the Flora treatments of the past 50 years differ considerably in their circumscription. In this study, morphometric analyses are used to test species limits to establish more stable morphological delimitations of the taxa. Material and methods – An examination of 15 morphological characters on 489 herbarium specimens was carried out and the data was analysed using Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA) with cross-validation, and Classification and Regression Tree (CART) analysis. Cyperus kibweanus was not further considered due to lack of material. Key results – Both PCA and LDA showed varying degrees of overlap in the nine remaining taxa, with no single group clearly separating in multivariate space. However, cross-validation clearly showed C. margaritaceus as a distinct entity despite its overwhelming presence in the PCA. Both LDA and CART failed to separate C. niveus as a distinct group as its specimens were dispersed among the other groups. Differing results were obtained for other taxa depending on the type of analysis. Cyperus margaritaceus, C. nduru, and C. sphaerocephalus were divided into two groups by CART but re-examination of the specimens does not definitively support the idea that these infraspecific groups represent separate taxa. Conclusions – The results show that eight morphospecies are recognised by LDA and six morphospecies by CART. Characters used to separate the taxa in Flora treatments scored high loadings in the analysis showing their high taxonomic utility value. The methods used can be applied to resolving other complexes in the Cyperaceae.

Phylogenomics and biogeography of arid-adapted Chlamydogobius goby fishes

The progressive aridification of the Australian continent from ∼ 20 million years ago posed severe challenges for the persistence of its resident biota. A key question involves the role of refugial habitats – specifically, their ability to mediate the effects of habitat loss and fragmentation, and their potential to shape opportunities for allopatric speciation. With freshwater species, for example, the patchiness, or absence, of water will constrain distributions. However, aridity may not necessarily isolate populations if disjunct refugia experience frequent hydrological connections. To investigate this potential dichotomy, we explored the evolutionary history of the Chlamydogobius gobies (Gobiiformes: Gobiidae), an arid-adapted genus of six small, benthic fish species that exploit all types of waterbodies (i.e. desert springs, waterholes and bore-fed wetlands, coastal estuarine creeks and mangroves) across parts of central and northern Australia. We used Anchored Phylogenomics to generate a highly resolved phylogeny of the group from sequence data for 260 nuclear loci. Buttressed by companion allozyme and mtDNA datasets, our molecular findings infer the diversification of Chlamydogobius in arid Australia, and provide a phylogenetic structure that cannot be simply explained by invoking allopatric speciation events reflecting current geographic proximity. Our findings are generally consistent with the existing morphological delimitation of species, with one exception: at the shallowest nodes of phylogenetic reconstruction, the molecular data do not fully support the current dichotomous delineation of C. japalpa from C. eremius in Kati Thanda-Lake Eyre-associated waterbodies. Together these findings illustrate the ability of structural (hydrological) connections to generate patterns of connectivity and isolation for an ecologically moderate disperser in response to ongoing habitat aridification. Finally, we explore the implications of these results for the immediate management of threatened (C. gloveri) and critically endangered (C. micropterus, C. squamigenus) congeners.

Taxonomy and Phylogeny of Peniophora Sensu Lato (Russulales, Basidiomycota).

Peniophora is an old corticioid genus, from which two small satellite genera, Dendrophora and Duportella, were derived based on morphological differences. Molecular systematic studies showed that they belong to Peniophoraceae, Russulales, but the inter- and intra-generic phylogenetic relationships are still unclear. Moreover, the species diversity of this group in subtropical and tropical Asia has not been sufficiently investigated and studied. In this study, we carried out an intensive taxonomic and phylogenetic study on Peniophora sensu lato based on analyses of concatenated ITS1-5.8S-ITS2 (ITS, Internal Transcribed Spacer) and 28S (D1-D2 domains of nuc 28S rDNA) sequence data of all available species worldwide. In the phylogenetic trees, species of Peniophora s. l. (sensu lato) including types of Peniophora s.s. (sensu stricto), Dendrophora and Duportella were interspersed within a strongly supported clade. It means that the morphological delimitations of the three genera are not reliable, and they should be regarded as a large genus. As a result, eight species of Duportella were transferred to Peniophora, although five of them have not been sequenced. Four new distinct lineages, corresponding to Peniophora cremicolor, P. major, P. shenghuae and P. vietnamensis spp. nov., were recovered in the trees. Peniophora taiwanensis is treated as a later synonym of P. malaiensis based on morphological and molecular evidence. Duportella renispora is excluded from Peniophoraceae, because BLAST results of the ITS and 28S sequences of the holotype showed that it is closely related to Amylostereum. Descriptions and illustrations are provided for the four new species, and an identification key is given for all 25 species of Peniophora in China. Our results indicated that the species diversity of the corticioid fungi in Asia is rich and deserves further study.

Descriptions of a new genus and a new species, Grylloprimevala jilina (Grylloblattidae) from China.

We erected a new genus (Grylloprimevala Zhou & Ren gen. nov.) and defined a new species (Grylloprimevala jilina Zhou & Ren sp. nov.) from a natural cave in the primeval forest of Jilin Province, China, according to the morphological, behavioral, and molecular evidence. Grylloprimevala gen. nov. is distinguishable from other genera of Grylloblattodea primarily by morphological characters, including the slightly concave posterior margin of the pronotum and no poorly sclerotized zones, six intramarginal and nine intermarginal setae on the cervical sclerite, one tooth on the lacinia, no pulvilli on tarsal segments, and a symmetrical epiproct with a pointed triangular and middle-depressed median projection on the posterior margin. Based on the morphological features mentioned above, we further identified a new species, G.jilina sp. nov. At the aspect of behavior, G.jilina sp. nov. displays the typical characteristics of troglobites, including degraded visual senses, developed body surface sensors, and predation between individuals. Furthermore, molecular phylogenetic analyses also supported the morphological delimitation of G.jilina sp. nov. due to the separate clade of G.jilina sp. nov. Our results provide materials for the determination and conservation of Grylloblattodea in China.

Quantification of the ichthyotoxic raphidophyte <italic>Chattonella marina</italic> complex by applying a droplet digital PCR

Quantifying the abundance of Chattonella species is necessary to effectively manage the threats from ichthyotoxic raphidophytes, which can cause large-scale mortality of aquacultured fish in temperate waters. The identification and cell counting of Chattonella species have been conducted primarily on living cells without fixation by light microscopy because routine fixatives do not retain their morphological features. Species belonging to the Chattonella marina complex, including C. marina and C. marina var. ovata, had high genetic similarities and the lack of clear morphological delimitations between the species. To estimate the abundance of C. marina complex in marine plankton samples, we developed a protocol based on the droplet digital polymerase chain reaction (ddPCR) assay, with C. marina complex-specific primers targeting the internal transcribed spacer (ITS) region of the rDNA. Cell abundance of the C. marina complex can be determined using the ITS copy number per cell, ranging from 25 ± 1 for C. marina to 112 ± 7 for C. marina var. ovata. There were no significant differences in ITS copies estimated by the ddPCR assay between environmental DNA samples from various localities spiked with the same number of cells of culture strains. This approach can be employed to improve the monitoring efficiency of various marine protists and to support the implementation of management for harmful algal blooms, which are difficult to analyze using microscopy alone.

Evidence from Phylogenomics and Morphology Provide Insights into the Phylogeny, Plastome Evolution, and Taxonomy of Kitagawia.

Kitagawia Pimenov is one of the segregate genera of Peucedanum sensu lato within the Apiaceae. The phylogenetic position and morphological delimitation of Kitagawia have been controversial. In this study, we used plastid genome (plastome) and nuclear ribosomal DNA (nrDNA) sequences to reconstruct the phylogeny of Kitagawia, along with comparative plastome and morphological analyses between Kitagawia and related taxa. The phylogenetic results identified that all examined Kitagawia species were divided into Subclade I and Subclade II within the tribe Selineae, and they were all distant from the representative members of Peucedanum sensu stricto. The plastomes of Kitagawia and related taxa showed visible differences in the LSC/IRa junction (JLA) and several hypervariable regions, which separated Subclade I and Subclade II from other taxa. Fruit anatomical and micromorphological characteristics, as well as general morphological characteristics, distinguished the four Kitagawia species within Subclade I from Subclade II and other related genera. This study supported the separation of Kitagawia from Peucedanum sensu lato, confirmed that Kitagawia belongs to Selineae, and two species (K. praeruptora and K. formosana) within Subclade II should be placed in a new genus. We believe that the "core" Kitagawia should be limited to Subclade I, and this genus can be distinguished by the association of a series of morphological characteristics. Overall, our study provides new insights into the phylogeny, plastome evolution, and taxonomy of Kitagawia.

A new species of hermit crab of the genus Pagurus Fabricius, 1775 (Crustacea: Anomura: Paguridae) from north-western Africa

One male and two female specimens of an undescribed species of the heterogeneous hermit crab genus Pagurus Fabricius, 1775, were found during the study of the collections of the Oceanographic Institute of Cádiz, containing specimens from African and European coasts collected during the scientific cruises carried out between in years 2008-2013. The new species is named Pagurus pectinidactylus n. sp., in reference to the presence of a well-developed toothless pectinate masticatory border in the dactylus of the left cheliped, composed by a row of tightly placed bristles forming a brush-like structure. The new species is compared to morphologically similar congeners, especially those that are genetically closest. Molecular phylogenetic analyses support the morphological delimitation, with P. pectinidactylus n. sp. forming a separate clade, more closely related to a group of South African species belonging to the Pagurus anachoretus group.

Exploring the diversity of Eupolyphaga Chopard, 1929 (Blattodea, Corydioidea): species delimitation based on morphology and molecular analysis.

Eupolyphaga Chopard, 1929 is a cockroach genus mainly endemic to China. In this study, the species diversity of this genus is further explored through morphology and molecular analysis. Four species are described new to science: Eupolyphagamiracidia Qiu, sp. nov., Eupolyphagaudenostyla Qiu, sp. nov., Eupolyphagareducta Qiu, sp. nov., and Eupolyphagasimila Qiu, sp. nov. New knowledge on some known species is added, including new distribution records and characteristics of females. Forty-five COI sequences were newly sequenced and a molecular species delimitation analysis was performed using ABGD method. Eighteen molecular operational taxonomic units were obtained by ABGD analysis, which are nearly consistent with the results of morphological delimitation.

Phylogenetic analysis of the gastropod genus Calliotropis Seguenza, 1902 (Vetigastropoda: Calliotropidae), including fossil and living species

The taxonomic content of the genus Calliotropis and the systematic positions of the fossil species referred to this genus have been under debate because of the striking resemblance they bear to their extant counterparts in terms of general shell morphology and ornament pattern. In a recent contribution, two subgenera of Calliotropis were preliminarily distinguished and considered to be a result of ecomorphological variation translated into evolutionary changes: shallow-reef ecomorphotypes, representing the fossil species of Calliotropis (Riselloidea), and deep-water ecomorphotypes, grouping the living forms of Calliotropis (Calliotropis). However, this division of Calliotropis species was based on qualitative grounds, lacking a quantitative phylogenetic analysis sampling both modern and fossil taxa. The present research aims to comprehensively revisit this systematic scheme after a morphological delimitation of calliotropid lineages. We use a quantitative phylogenetic analysis to shed light on the evolutionary history of this group of gastropods. Our results indicate that the Mesozoic genus ‘Calliotropis’ is not monophyletic, but living species comprise a monophyletic group with a Pliocene–Recent distribution. Fossil ‘Calliotropis’ species represent a paraphyletic assemblage composed of different clades: the monophyletic Riselloidea (Cossmann) including only Jurassic species; a Palaeogene group represented by the new genus Arachnotropis gen. nov.; and a monophyletic Triassic group that matches the content of the previously described genus Trochonodus Nützel et al., 2003. The genus Ambercyclus Ferrari et al., 2014 is monophyletic and also related to the above-mentioned taxa. http://zoobank.org/urn:lsid:zoobank.org:pub:0BF29053-3D67-41A4-923D-5621D448AD61

Morphology, phylogeny, and species delimitation of Micryletta (Anura: Microhylidae) reveals a new species from Singapore

The genus Micryletta, also known as paddy frogs, ranges across much of south, east, and southeast Asia. Due to their relatively broad distribution and overall morphological similarities, many species have gone undetected until recently, largely owing to the use of molecular data. Consequently, the species diversity within this genus has quadrupled in just three years from three species prior to 2018, to 12 species in 2021, indicating that the systematics of this genus is still poorly understood. As such, we assembled the most comprehensive molecular phylogeny of Micryletta hitherto including novel sequences from a previously unsampled population from Singapore to assess the species diversity within this genus. In particular, we investigate the population from Singapore whose specific identity remains in question due to the lack of voucher specimens and genetic material. Our results show that the Singapore population represents a strongly supported and distinct lineage that is most closely related to M. inornata sensu stricto from Sumatra, Indonesia. Morphological and species delimitation analyses corroborate its distinction as a new species, which we describe herein as M. subaraji sp. nov. This and recent new taxon discoveries in Singapore demonstrate that the biodiversity of the highly urbanized island-state is still far from being fully realized and underscores the need for continued systematic surveys and protection of remaining habitats.

Phylogeny of Calvittacus Revealing a New Species from China (Acari: Eriophyidae).

Simple SummaryEriophyoid mites (Eriophyoidea) are strictly phytophagous, consisting of over 5000 extant species, in which many species are pests. The genus Calvittacus includes only four species and is endemic in the Oriental Region. In this study, we combined morphological characters and molecular approaches to delimitate the Calvittacus species and recovered one new species, Calvittacus spectabilus sp. nov. The new species is vagrant on lower leaf surface, causing no apparent symptom to the host plant.Eriophyoid mites (Eriophyoidea) are distributed worldwide and are the largest superfamily in the Acari. After over one and a half centuries of field surveys, regional fauna of eriophyoid mites remains unclear. The genus Calvittacus Xue, Song & Hong 2006 is endemic in the Oriental Region, including four species—C. chenius Xue, Wang, Song & Hong, 2009; C. mollissimus Han, Xue & Hong, 2017; C. regiae Xue, Song & Hong 2006; and C. swidanus Song, Xue & Hong, 2009. In this study, we describe one new species, Calvittacus spectabilus sp. nov., collected on Bougainvillea spectabilis (Nyctaginaceae) from China (the Oriental Region). Phylogenetic analysis based on mitochondrial COI barcode sequences confirmed the C. spectabilus sp. nov., coinciding with the morphological delimitation. We further discussed the potential distribution of the Calvittacus species and underlined the integrative approaches in eriophyoid mite delimitation.

Two new hermit crab species of Diogenes (Crustacea: Decapoda: Diogenidae) from Atlanto-Mediterranean coasts of Iberian Peninsula: Poleward migrants or merely overlooked indigenous species?

A new hermit crab species of the genus Diogenes with reddish‐orange cheliped, Diogenes erythromanus sp. nov., is described and illustrated based on specimens from the Mediterranean coasts of the Iberian Peninsula, southern Spain. In addition, a second morphotype originating from Mauritanian waters and morphologically very close to D. erythromanus sp. nov. is described as a different species, D. arguinensis sp. nov. The new species are here compared to morphologically similar congeners, especially to those inhabiting the same geographical range. Diogenes erythromanus sp. nov. is distinguishable from other Diogenes primarily by the shape and armature of the left cheliped, with a palm slightly higher than long, with a ridge of spines running along the proximal lower margin that continues with a series of spinose rows forming a central band parallel to the upper margin of the palm. The palm in D. arguinensis sp. nov. is longer than high and shows similar proximal ridge, but without central spinose ridge. The shape of the cheliped is also different in D. arguinensis sp. nov., with long dactylus, which is also flattened and twisted. Sequences from two mitochondrial and one nuclear genes, and comparative analyses with other available sequences for the genus, are also included. Molecular phylogenetic analyses support the morphological delimitation, with D. erythromanus sp. nov. and D. arguinensis sp. nov. forming a separate group, more related to other tropical species, which raises different possible explanations for its presence in the Iberian Peninsula.

Hidden generic diversity in desmids: description of Pseudomicrasterias gen. nov. (Desmidiaceae, Zygnematophyceae)

ABSTRACT The taxonomy and nomenclature of Micrasterias arcuata are very problematic because of a wide morphological variation and the large number of poorly circumscribed infraspecific taxa. This study aimed at evaluating the phylogenetic position of strains traditionally assigned to M. arcuata based on molecular and phylogenetic approaches, and morphometric analyses. Multigene analyses were performed using the nuclear SSU rDNA and both chloroplast rbcL and psaA markers. Genetic analyses revealed that all three investigated strains of M. arcuata formed reasonably well-supported lineages, separate from all species of the core Micrasterias lineage and closely related to the Euastrum 2 lineage. Morphometric analyses exhibited differences among strains revealing important trends for morphological differentiation and delimitation of infraspecific taxa assigned to M. arcuata. All three investigated strains are separated by their morphological features and represent different taxonomic entities from the molecular and phylogenetic points of view. Available data support the proposal of Pseudomicrasterias gen. nov. within the family Desmidiaceae. One infraspecific taxon is erected to species level and classified as new combination of Pseudomicrasterias, and two new species are recognized.

Dioscorea magnibracteata (Dioscoreaceae), a new species from western Ecuador based on the unpublished work of Temple Clayton

Dioscorea magnibracteata is described and formally presented as a new species based on specimens identified with unpublished names by Temple Clayton. This species occurs exclusively in the seasonally deciduous dry tropical forest of coastal Ecuador, a fairly threatened environment. This new species is monoecious and features staminate flowers with six stamens but differs markedly from all other species of Neotropical Dioscorea by the staminate inflorescences with very large cymbiform bracts and toothed to lacerated margin. We provide a morphological description as well as information on habitat, geographic distribution and taxonomic comments that include the morphological delimitation of the new species and similarities to other species of Dioscorea sect. Monadelpha.