Search Results (38)

The kelp genus Eisenia Areschoug is represented by two species in the Southeast Pacific: Eisenia cokeri, distributed in Peru and Chile, and E. gracilis, endemic to Peru. However, the taxonomic distinction between these species has long been questioned, and it remains unclear whether E. cokeri is conspecific with the Northeast Pacific species E. arborea. To address these issues, we conducted an integrative taxonomic assessment combining morphological analyses, molecular phylogenetics, and molecular species delimitation approaches. Sampling for morphological and molecular analyses was carried out in subtidal zones at five localities along the Peruvian coast, and an additional locality in Chile was included for molecular analyses where E. cokeri was documented. Peruvian Eisenia species exhibited consistent morphological differentiation, including differences in thallus size, holdfast diameter, stipe modifications (e.g., longitudinal division and pseudostipe formation), frond division, frond margins, and surface roughness, as supported by morphometric analyses. Phylogenetic reconstructions based on mitochondrial and chloroplast markers, together with concordant results from multiple species delimitation methods (ABGD, GMYC, and bPTP), consistently recovered three independent evolutionary lineages corresponding to E. cokeri, E. gracilis, and a distinct lineage of Eisenia from the Desventuradas Islands (Chile). Our results confirm the taxonomic distinctiveness of E. cokeri and E. gracilis, demonstrate that E. cokeri is genetically distinct from E. arborea, and reveal the presence of a previously unrecognized lineage of Eisenia in the Southeast Pacific. These findings refine species boundaries within the genus and provide a robust framework for the management and conservation of these endemic, foundation, habitat-forming species. Full article

Despite extensive research into green microalgae belonging to the genus Chloroidium, their species diversity and biotechnological potential remain poorly characterized. The strain VKM Al-418, the subject of this study, was isolated from the soil of Duvannyi Yar (Russian Federation). The independent species status of this strain is supported by distinct morphological characteristics, robust phylogenetic placement based on the 18S-ITS1-5.8S-ITS2 fragment, and unique features in the secondary structures of both ITS1 and ITS2, including one compensatory base change (CBC) in the highly conserved helix III of ITS2. Additionally, the species delimitation was also confirmed using five independent algorithmic approaches analyzing four different DNA barcodes. The concatenated ITS1-5.8S-ITS2 fragment is more reliable for species discrimination than the individual ITS1 or ITS2 barcodes. Of the species delimitation methods evaluated, ASAP (Assemble Species by Automatic Partitioning) and GMYC (Generalized Mixed Yule Coalescent) performed best in distinguishing Chloroidium species across multiple barcode regions in our analysis. The fatty acid profile of strain VKM Al-418 was analyzed at 9 °C, 22 °C, and 27 °C and exhibited high plasticity in response to temperature, indicative of an adaptive strategy to its harsh environment. Using this integrative taxonomic approach, we describe Chloroidium pseudoellipsoideum sp. nov., a new species with a distinct phylogenetic positioning and promising biotechnological properties. Full article

Polynema Haliday, 1833 (Hymenoptera: Chalcidoidea: Mymaridae), one of the most species-rich genera in the family, comprises egg parasitoids with diverse hosts across multiple insect orders, some serving as biological control agents for agricultural and forestry pests. The subgenus Polynema (Doriclytus Foerster, 1847), characterized by pronounced morphological conservatism, has historical taxonomic challenges due to reliance on external morphological characteristics. This study employed an integrative taxonomic approach, combining morphological and molecular analyses, to investigate P. (Doriclytus) diversity in the Oriental region of China. Eight species were identified, including three new species—P. (Doriclytus) acutum Wang & Aishan, sp. nov., P. (Doriclytus) daliense Wang & Aishan, sp. nov., and P. (Doriclytus) longicornia Wang & Aishan, sp. nov.—and five species newly recorded from China: P. (Doriclytus) alalatum Rehmat & Anis, 2016, P. (Doriclytus) bicolorigastra Rehmat & Anis, 2016, P. (Doriclytus) dhenkunde Mani & Saraswat, 1973, P. (Doriclytus) dunense Hayat & Anis, 1999, and P. (Doriclytus) tyakshiense Irfan & Anis, 2023. Comprehensive morphological descriptions and diagnostic illustrations are provided for all new taxa, with key diagnostic features detailed for the newly recorded species. Molecular analysis of COI sequences using both the Assemble Species by Automatic Partitioning (ASAP) and Generalized Mixed Yule Coalescent (GMYC) models yielded congruent species delimitation results, with genetic distances between delimited species showing maximum intraspecific divergence of 1.51% and interspecific divergences of 3–12% within the 470 bp COI barcode region. The deposition of 32 novel COI sequences in GenBank significantly enhances molecular resources for Mymaridae systematics. Full article

Some Melanothamnus species have been documented growing epiphytically on other algae in seaweed aquaculture farms as fouling organisms. Such turf-forming Polysiphonia-looking algae were collected from a small (<1.0 km² area) Agarophyton tenuistipitata (Gracilariaceae, Gracilariales) farm on the east coast of the Bay of Bengal and examined for their taxonomy. DNA was extracted from silica gel-preserved specimens, and plastid-encoded rbcL, nuclear-encoded small subunit SSU, large subunit LSU, and universal plastid amplicon (UPA) were amplified and sequenced. Maximum likelihood (ML) and Bayesian inference were performed for the phylogenetic analysis. Four single-locus species delimitation methods (SDMs), namely, the generalized mixed Yule-coalescent (GMYC) method, a Poisson tree processes (PTP) model, the automatic barcode gap discovery (ABGD), and the assemble species by automatic partitioning (ASAP) method, were performed to segregate the putative species from other taxa in the Polysiphonia sensu lato clades. Our results revealed that rbcL had 1.4% interspecific genetic divergence, whereas LSU, UPA, and SSU had 1.6%, 2.5%, and 5.4% genetic divergence, respectively, from the nearest neighbors. Both comparative genetic and distinct morphological data revealed that the collected Bay of Bengal specimens comprise a species new to science. In addition, the above-mentioned SDMs supported the genetic data and segregated our specimens as Melanothamnus coxsbazarensis sp. nov. as a distinct species. Full article

The genus Grypoctonus Speiser, 1928 (Diptera: Asilidae) is a fuzzy-looking assassin fly, and adults have only been observed in autumn and winter. Currently containing four described species, this genus is readily distinguished from other Chinese asilids by the presence of two r-m crossveins. Through integrative taxonomic analysis of over 200 specimens from multiple Chinese provinces, we combined morphological assessment with DNA barcoding and four species delimitation methods (ABGD, ASAP, mPTP, and GMYC). Four species are newly described: G. aureus sp. nov., G. sagittatus sp. nov., G. solarius sp. nov., and G. yongshani sp. nov. (the latter described solely from morphological examination of historical specimens). Genetic analyses revealed distinct barcoding gaps, with an interspecific distance of 1.38–7.07% versus an intraspecific distance of no more than 0.92%. We revised the generic diagnosis, provided a distribution map, and a revised key to all known species of Grypoctonus. Full article

Discogobio is a genus of small, economically important freshwater fishes that are widely distributed in Southwestern China. The species of the genus are morphologically very similar, which makes their taxonomic identification quite challenging. DNA barcoding technology can identify species at the molecular level, thus overcoming the limitations of morphological classification. In this study, we collected 16 morphological species of Discogobio from China, analyzed the mitochondrial cytochrome oxidase I subunit (COI) gene sequences of 206 samples, and applied DNA barcoding to identify the species. The COI amplicon was 651 bp in length, and the mean base contents were: (T) 28.83%, (C) 27.63%, (A) 25.97%, (G) 17.57%. The AT content (54.8%) was higher, and the base composition was biased. The intraspecific differences in the genus Discogobio were not significant, and the genetic distances were all less than 2%. The average interspecific genetic distances (3.94%) were about 18.8 times the average intraspecific genetic distances (0.21%), suggesting that there are barcode gaps among the species of the genus Discogobio. Five different species definition methods, Automatic Barcode Gap Discovery (ABGD), Assemble Species by Automatic Partitioning (ASAP), Bayesian Poisson Tree Process (bPTP), Generalized Mixed Yule Combination (GMYC), and Refined Single Linkage (RESL), were used to infer molecular operational taxonomic units (MOTU). The number of MOTUs ranged from 9 to 18. Phylogenetic analysis based on COI gene haplotypes showed that most species formed well-evolved branches on the phylogenetic tree, and the clustering among species was obvious without mixing. The results of this study provide reliable DNA barcoding information for species identification within the genus Discogobio, which is of great significance for taxonomic identification. Full article

Background: The phylogenetic resolution within the Gloydius halys-intermedius Complex remains debatable due to the following reasons: loci selection in previous studies varied between authors; limited dataset (1−5 mitochondrial or nuclear gene fragments); lack of sampling density; and nodal supports at specific nodes remain weak, specifically within Gloydius cognatus, G. halys, and G. stejnegeri. Objectives: To revise the taxonomic and phylogenetic relationships within the G. halys-intermedius Complex, we reconstructed the molecular phylogeny and performed species delimitation based on the complete mitochondrial genomes. Methods: In this study, twelve nomenclatural groups of Gloydius species were involved in the computation of Bayesian phylogenomic inference, five of the twelve nomenclature groups were newly sequenced, while the rest were acquired from the National Center for Biotechnology Information (NCBI). The Bayesian phylogenomic inference was constructed based on 13 mitochondrial protein-coding genes. Species delimitation was performed by two distance-based methods (ABGD and ASAP) and two tree-based methods (GMYC and bPTP). Results: This research resolved the systematic relationship within the G. intermedius Complex with the support of mitogenome-based phylogenomics, while indicating cryptic diversity within the Gloydius halys-intermedius Complex: G. intermedius samples from South Korea show as paraphyletic to the cluster of the samples from northeastern China. Species delimitation results based on four models resemble each other, supporting Gloydius caucasicus, G. cognatus, G. halys, and G. stejnegeri, each representing full species. The species delimitation results of this research also resemble the nomenclatural species based on previous morphometrical results. This research indicates that species delimitation efforts based on the phylogenomic approach would likely resolve complex evolutionary relationships. Full article

The diversity of non-biting midges (Chironomidae, Diptera) remains an unresolved topic, with estimates of species numbers ranging from 6000 to 15,000 according to various authors. To assess Chironomidae diversity in Lithuania, we evaluate the effectiveness of COI gene-based species delimitation methods for providing rapid diversity estimates. Nevertheless, differences between tree-based and distance-based approaches can result in varying group classifications, which may cause species numbers to be overestimated or underestimated. For our study, we analyzed a dataset of 109 specimens sampled from six Lithuanian streams. By applying multiple methods, such as Assemble Species by Automatic Partitioning (ASAP), Automatic Barcode Gap Discovery (ABGD), the generalized mixed Yule-coalescent (GMYC) model, and the Bayesian implementation of the Poisson Tree Processes (bPTP) model, we found that species estimates ranged from 28 to 58. Among these methods, ASAP proved to be the most effective for our dataset, identifying 58 putative species. These results reinforce our assumption that the current understanding of Chironomidae species diversity is incomplete. Full article

During the present study, DNA sequence and morphological data were used to delineate species boundaries in the velvet worm, Peripatopsis sedgwicki species complex. The combined mitochondrial cytochrome c oxidase subunit one (COI) and the nuclear 18S rRNA loci were phylogenetically analyzed using Bayesian inference and maximum likelihood platforms that both demonstrated the presence of four, statistically well-supported clades (A–D). In addition, five species delimitation methods (ASAP, bPTP, bGMYC, STACEY and iBPP) were used on the combined DNA sequence data to identify possible novel lineages. All five species delimitation methods supported the distinction of the Fort Fordyce Nature Reserve specimens in the Eastern Cape province, however, in the main P. sedgwicki s.l. species complex, the species delimitation methods revealed a variable number of novel operational taxonomic units. Gross morphological characters were of limited utility, with only the leg pair number in the Fort Fordyce Nature Reserve specimens and the white head-collar of the Van Stadens Wildflower Nature Reserve specimens being diagnostic. The RADseq results from the earlier study of P. sedgwicki s.l. provided highly congruent results with the four clades observed in the present study. The distribution of P. sedgwicki s.s. (clade B) is restricted to the western portions of its distribution in the Afrotemperate forested regions of the Western Cape Province, South Africa. Three novel species, P. collarium sp. nov., (clade C) P. margaritarius sp. nov., (clade A) and P. orientalis sp. nov., (clade D) are described, of which the first two species are narrow range endemics. The present study, along with several recent systematic studies of velvet worms affirms the importance of fine-scale sampling to detect and document the alpha taxonomic diversity of Onychophora. Full article

Stauroneis (Naviculales, Bacillariaceae) are widespread, mostly in fresh-water habitats, and account for 343 species. They are described mainly on the basis of morphology and morphometric traits. These characteristics vary during life cycles and may overlap between species, making their identification difficult. We isolated two strains of naviculoid diatoms and examined them using an integrative approach (phylogenetic, morphological, ultrastructural data, and life cycle). Phylogenetic analyses based on chloroplast rbcL gene data showed affinity of the new strains to the genus Stauroneis. Our algae share morphological features typical of Stauroneis but differ from similar species in minimal valve length measurements, valve apex shape, and minimal number of striae in 10 μm. Two strains are distinct from each other in maximal valve length and width, partially valve shape, the number of areolae in 10 μm, and cingulum structure. It was revealed that the strains reproduce via isogamy. Three species delimitation methods (ASAP, PTP, and GMYC) also confirmed that the two closely related new strains represent distinct species. Based on molecular data and phenotypic traits examined within the framework of an integrative approach, we describe two new isolates as Stauroneis urbani sp. nov. and Stauroneis edaphica sp. nov. Full article

To date, five species of reddish-brown Neotriplax have been described, but their highly similar body color and other phenotypic traits make accurate taxonomy challenging. To clarify species-level taxonomy and validate potential new species, the cytochrome oxidase subunit I (COI) was used for phylogenetic analysis and the geometric morphometrics of elytron, pronotum, and hind wing were employed to distinguish all reddish-brown Neotriplax species. Phylogenetic results using maximum likelihood and Bayesian analyses of COI sequences aligned well with the current taxonomy of the Neotriplax species group. Significant K₂P divergences, with no overlap between intra- and interspecific genetic distances, were obtained in Neotriplax species. The automatic barcode gap discovery (ABGD), assemble species by automatic partitioning (ASAP), and generalized mixed Yule coalescent (GMYC) approaches concurred, dividing the similar species into eight molecular operational taxonomic units (MOTUs). Geometric morphometric analysis using pronotum, elytron, hind wing shape and wing vein patterns also validated the classification of all eight species. By integrating these analytical approaches with morphological evidence, we successfully delineated the reddish-brown species of Neotriplax into eight species with three new species: N. qinghaiensis sp. nov., N. maoershanensis sp. nov., and N. guangxiensis sp. nov. Furthermore, we documented the first record of N. lewisii in China. This study underscores the utility of an integrative taxonomy approach in species delimitation within Neotriplax and serves as a reference for the taxonomic revision of other morphologically challenging beetles through integrative taxonomy. Full article

The genus Stictochironomus (Diptera: Chironomidae) has an almost worldwide distribution, with more than 30 species. However, species delimitation and identification based on the markings on the wings and legs are controversial and uncertain. In this study, we focused on color patterns to review the adults of the genus from China, and two new species (S. trifuscipes sp. nov. and S. quadrimaculatus sp. nov.) are described and figured. DNA barcodes can accurately separate the two new species with specific color patterns. However, heterospecific individuals form a monophyletic cluster in the phylogeny tree. For example, S. maculipennis (Meigen) and S. pictulus (Meigen), which have a lower interspecific genetic divergence, form a single clade. Sequences with the same species name but with high intraspecific distance form more than one phylogenetic clade, such as S. sticticus (Fabricius) of three clades, S. pictulus of four clades, S. akizukii (Tokunaga) and S. juncaii Qi, Shi, and Wang of two clades, might have potential cryptic species diversity. Species delimitation analysis using ASAP, PTP, and GMYC clearly delineated them as separate species. Consequently, color patterns are a good diagnostic characteristic for species delimitation in Stictochironomus. The distance-based analysis shows that a threshold of 4.5–7.7% is appropriate for species delimitation in Stictochironomus. Additionally, an updated key including color pattern variation for male adults of known Stictochironomus species from China is provided. Full article

Groups with morphological stasis are an interesting framework to address putative cryptic species that may be hidden behind traditional taxonomic treatments, particularly when distribution ranges suggest disjunct and environmentally heterogeneous biogeographic patterns. New hypotheses of delimitation of evolutionary independent units can lead to the identification of different biogeographic processes, laying the foundation to investigate their historical and ecological significance. Jasione is a plant genus with a distribution centered in the Mediterranean basin, characterized by significant morphological stasis. Within the western Mediterranean J. gr. crispa species complex, J. sessiliflora s.l. and allied taxa form a distinct group, occupying environmentally diverse regions. At least two ploidy levels, diploid and tetraploid, are known to occur in the group. The internal variability is assessed with phylogenetic tools, viz. GMYC and ASAP, for species delimitation. The results are compared with other lines of evidence, including morphology and cytology. The fitting of distribution patterns of the inferred entities to chorological subprovinces is also used as a biogeographical and environmental framework to test the species hypothesis. Despite the scarcity of diagnostic morphological characters in the group, phylogenetic delimitation supports the description of at least one cryptic species, a narrow endemic in the NE Iberian Peninsula. Moreover, the results support the segregation of a thermophilic group of populations in eastern Iberia from J. sessiliflora. Ploidy variation from a wide geographical survey supports the systematic rearrangement suggested by species delimitation. Taxonomic reorganization in J. sessiliflora s.l. would allow ecological interpretations of distribution patterns in great accordance with biogeographical regionalization at the subprovince level, supporting geobotanical boundaries as a framework to interpret species ecological coherence of cryptic lineages. These results suggest that species differentiation, together with geographic isolation and polyploidization, is associated with adaptation to different environments, shifting from more to less thermophilic conditions. Thus, the recognition of concealed evolutionary entities is essential to correctly interpret biogeographical patterns in regions with a complex geologic and evolutionary history, such as the Mediterranean basin, and biogeographical units emerge as biologically sound frameworks to test the species hypothesis. Full article

The genus Hamadryas has a neotropical distribution. In 1983, the subspecies H. glauconome grisea from Mexico was recognized with subtle and subjective differences in color, size and distribution and limited to the northwest. Since then, there has been a debate about whether it is a different lineage from H. glauconome because adult-stage morphology studies have not found significant differences. This study aims to delimitate H. g. glauconome and H. g. grisea lineages with two sources of evidence: ecological and molecular—the former through ecological niche modeling using the accessible area for the species and estimating the minimum volume ellipsoid overlapping as a fundamental niche using occurrences databases. The molecular evidence is found through the methods of phylogenetic inference and the generalized mixed yule coalescent approach, using sequences of cytochrome oxidase I. Ecological and molecular evidence suggest that H. g. grisea is a different lineage from H. glauconome. Also, molecular evidence of a third lineage from the south of Texas needs further study. This study suggests that different evidence should be provided when morphology is not enough for delimiting species, especially in recently diverged species. Furthermore, the H. g. grisea cytochrome oxidase I sequence (658 bp) is published for the first time. Full article

To date, a rather large set of both mathematical theories for species delimitation, based on single-locus genetic data, and their implementations as software products, has been accumulated. Comparison of the efficiencies of different delineation methods in the task of accumulating and analyzing data with reference to different taxa in different regions, is vital. The aim of this study was to compare the efficiency of fifteen single-locus species delimitation methods using the example of a fish species found in a single lake in European Russia (Lake Plescheyevo) with reference to other sequences of revealed taxa deposited in international databases. We analyzed 186 original COI sequences belonging to 24 haplotypes, and 101 other sequences previously deposited in GenBank and BOLD. Comparison of all 15 alternative taxonomies demonstrated that all methods adequately separate only the genera, while the number of delimited mOTUs differed from 16 (locMin) to 43 (HwM/CoMa). We can assume that the effectiveness of each method is correlated with the number of matches based on Ctax and MatchRatio criteria. The most comparable results were provided by bGMYC, mPTP, STACEY, KoT and ASAP and the most synchronous results were obtained from bGMYC, mPTP, STACEY and ASAP. We believe that these results are maximally realistic in the number of revealed mOTUs. A high genetic diversity, resulting in the existence of several mOTUs and phylogenetic lineages within many species, demonstrates the usefulness of the “polymorphic species” concept, which does not underestimate species richness and does not prevent the rational use and protection of biodiversity. Full article