Species-rich Genus Research Articles

<i>Ganoderma</i> (Ganodermataceae, Polyporales): Historical perspectives, recent advances, and future research in Sri Lanka

<italic>Ganoderma</italic> P. Karst. has been used in traditional Chinese medicine for thousands of years for maintaining vivacity and longevity. This fungus is a cosmopolitan genus of mushrooms that can cause root and butt rot diseases on many woody tree species. <italic>Ganoderma</italic> is a species-rich genus, and many members are found in subtropical and tropical regions. Some <italic>Ganoderma</italic> species are well-known for being abundant sources of highly active bioactive substances like polysaccharides, proteins, steroids, and triterpenoids. The numerous metabolic processes of <italic>Ganoderma</italic> have been studied both <italic>in vitro</italic> and <italic>in vivo</italic>. However, it is debatable if <italic>Ganoderma</italic> is a nutritional supplement that promotes health, or a medication used for therapeutic purposes. Products made from <italic>Ganoderma</italic> have been marketed as potent food and medication supplements with positive health effects. Over the past three decades, the <italic>Ganoderma</italic> market has experienced significant growth, and hundreds of products are currently being offered on the market. However, in Sri Lanka, there hasn't been much research done on <italic>Ganoderma</italic>. Hence, a comprehensive account of the historical perspective, recent advances, and future trends of <italic>Ganoderma</italic> research in Sri Lanka is provided in this review. Furthermore, this review aims to increase the research interest, evaluate the recent developments, and address the missing gaps in research on <italic>Ganoderma</italic>.

Pitcairnia mineira (Bromeliaceae): A new rheophytic species from the Espinhaço Range, Brazil

Pitcairnia is a species-rich genus with about 400 species distributed mainly in the Neotropics. We propose and diagnose a new rheophytic species of Pitcairnia, P. mineira, found in campos rupestres vegetation in the Southern Espinhaço Province (Minas Gerais State). We provide a description, including anatomical characters, illustration, distribution map, photographs, preliminary conservation assessment and comments on the distribution, habitat, phenology, and taxonomy of the new species. We also include an identification key to all species of Pitcairnia in the Espinhaço Range, Minas Gerais, Brazil.

Fungal diversity in the tropics: Entoloma spp. in Panama

Entoloma (Agaricales, Basidiomycota) is a species-rich genus with approximately 2000 species known worldwide. In Central America, however, information about the species of this genus is sparse, despite the generally high biodiversity in this region. Recently, 124 specimens of Entoloma were collected in Panama, Chiriquí Province. In the present publication, the morphology of 20 species represented by more than one specimen is described and depicted with photographs, line drawings, and scanning electron micrographs. Molecular phylograms based on ITS or concatenated ITS and partial nc LSU rDNA sequences are provided. The taxonomic status of these species is evaluated and 17 species of Entoloma are described as new to science. Only one species could be assigned to an already known species, viz. Entoloma belouvense. Nolanea albertinae, described from Brazil, appeared similar and is combined in E. belouvense on varietal level. The identifications of two further species are uncertain. At least 30 other species, including potentially new species, cannot formally be described due to insufficient material. A preliminary key to the species of the genus Entoloma in Panama is provided. The spatial shape of the polyhedroid basidiospores of Entoloma spp. is discussed based on literature and the micrographs generated for the present study. Our re-evaluations indicate that the type of polyhedroid basidiospore and the structure of its base are not reliable as diagnostic characters for the delimitation of subgenera in Entoloma.

Epilithic diatoms (Bacillariophyceae) in a tropical Andean River of Southwest Colombia

Abstract In tropical regions there are a large number of species of diatoms that have not been identified yet. This research aimed to study the composition of epilithic diatom flora found in samples collected in Dagua River a tropical Andean hydrographical basin located to the southwest of Colombia. Samplings were performed in three stations with their respective three replicas between January and April 2018 to collect samples for identification of diatom (Class Bacillariophyceae). These samples were analyzed with light microscopy and interferential contrast microscopy. The results indicated the occurrence of 18 taxa distributed in 9 families and 11 genera. Two of these are new records for Colombia: Navicula incarum and Fragilaria aff. socia. The most species-rich genera was Navicula. A comparison with the diatom flora of the region shows that 9 species were recorded in common with the Cali River.

Characterizing Asplenium achalense (Aspleniaceae), a misunderstood species of Argentine flora: morphological, palynological and distributional evidences

Asplenium (Aspleniaceae) is taxonomically one of the most complex fern genera with about 700 species, nearly cosmopolitan in distribution. In Argentina, Asplenium constitutes the most species-rich fern genus, with 38 taxa. Among these species, the delimitation of Asplenium achalense remain poorly understood. Some authors consider A. serra as a variant of A. achalense, or even the last species has been considered as a complex of species. The finding of a population of Asplenium achalense in Yungas after three decades without observations in the wild and neither registering more recently herbarium specimens, made it possible to analyse living material and observe new diagnostic characters present in rachises and laminae scales, glandular hairs in petioles and rachises along with spore wall features, that are critical to delimitate A. achalense as a well-defined taxon, endemics of north-west to central Argentina.

Three names, one species: junior synonyms for the Atlantic Forest emerald dragonfly Navicordulia atlantica (Odonata: Corduliidae s.s.)

Three Atlantic Forest endemic species of emerald dragonflies of the genus Navicordulia Machado & Costa, 1995 are reviewed through a morphological comparative analysis. All name-bearing types and additional specimens of the Navicordulia atlantica-complex—Navicordulia atlantica Machado & Costa, 1995, Navicordulia mielkei Machado & Costa, 1995 and Navicordulia miersi Machado & Costa, 1995—were investigated to assess their taxonomic and nomenclatural status. Based on our results the hypothesis of these three nomina corresponding to distinct species is no longer supported. The proportional size of caudal appendages, an additional crossvein in cubito-anal space in the hind wing, as well as minor differences in coloration of pterostigma are not reliable diagnostic characters for supporting their specific status. We consider the three simultaneously available nomina as synonyms, and by action of the first reviser, Navicordulia atlantica Machado & Costa, 1995 is selected as valid nomen, hence N. mielkei syn. nov. and N. miersi syn. nov. are their subjective junior synonyms. Photos, other illustrations, and a new species-level diagnosis are given. Despite of the advances of taxonomic knowledge of Navicordulia, the second species-rich corduliid genus in the Neotropical region, the status of some species still necessitates a full revision.

Color Variation and Habitat Use in Liolaemus silvai

Liolaemus is a species-rich genus endemic to South America with relatively little known about the biology of most of the > 200 included species. One species, L. silvai is common in the coastal Atacama Desert and is sexually dimorphic. We studied their phenotypic variation in color and body size, as well as habitat use by capturing lizards active on the surface. To assess phenotypic variation, we categorized the color morph of each lizard based on visible coloration in their ventral throat region and their ventral body from the shoulder girdle to the hips. We also sexed each lizard, measured snout–vent length and body mass, and recorded incidences of tail breakage. For habitat use we measured perch height, distance from the rock edge to nearest vegetation, and the height of the rocks on which lizards were initially sighted. We assessed habitat selection by comparing perch characteristics to features available in the habitat by pairing capture rocks with the nearest rock in a random direction from the initial perch site. Male L. silvai were significantly larger than females, but color morph and tail break frequency were independent of sex. Lizards used rocks that were significantly closer to vegetation than random rocks available in the environment independently of sex or color morph. We document the same pattern for perch height. Future studies are needed to examine the exact role of vegetation for L. silvai.

Flora of water bodies in the eastern part of the Dnieper-Donetsk depression

The article presents results of the study of flora of the reservoirs in the eastern part of the Dnieper-Donetsk basin. An annotated list of flora was compiled on the base of personal field research, analysis of herbarium materials, and available literature data. The annotated list provides information on the herbarium specimens, species distribution in the study region, its general geographic distribution, habitat ecology, conservation status, life form, economic significance, and known literature references in the study region. It is established that the flora of water bodies of the area in question includes at least 61 species of higher aquatic vascular plants. The family Potamogetonaceae is the most species-rich (18 species, about 30% of the total aquatic flora of the region). The most species-rich genus is Potamogeton (16 species); other taxa are represented by a small number of species. A dominant life form is a group of submerged rooted aerohydatophytes, which numbers 28 species (45.9% of the total flora); the rooted aerohydatophytes with leaves floating on the water surface account for 12 species (19.6%). In terms of geographical distribution, the most abundant is the species group with a circumpolar type of area (28 species). Fourteen species have Eurasian ranges. Other area types are represented by a small number of species. The aquatic flora of the eastern part of the Dnieper-Donetsk basin has a high sozological value. Twenty-six species (42.6% of the flora) have conservation status. The Red Book of Ukraine includes six species, viz. Aldrovanda vesiculosa L., Utricularia intermedia Hayne, U. minor L., Salvinia natans (L.) All., Trapa natans L., and Nymphoides peltate (S.G. Gmel.) Kuntze. Three of them are listed in Annex I of the Berne Convention, and the other three are tertiary relics. Three species are included in the European Red List of Vascular Plants. The list of rare, endangered, typical, and in need of special protection plant groups (Green Book…., 2009) includes 14 aquatic assemblages. Recently, against the background of a general decrease in autochthonous floristic diversity, new invasive species have appeared in the region, behaving aggressively towards the native flora: Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms.

Comparative Analysis of Chloroplast Genomes of Thalassiosira Species

Thalassiosira is a species-rich genus in Bacillariophyta with important ecological contribution to primary productivity but can also pose negative impact on ecology by developing harmful algal blooms (HABs). However, genomic resources of only a few Thalassiosira species are currently available. Here, we constructed complete chloroplast genomes (cpDNAs) of six Thalassiosira strains (representing six Thalassiosira species T. rotula, T. profunda, T. nordenskioeldii, T. tenera, T. weissflogii, and Thalassiosira sp.), and compared them with published cpDNAs of other diatoms. Comparative analysis revealed that Thalassiosira cpDNAs have generally conventional and conserved quadripartite structure with important exceptions. Gene orders of cpDNAs of Thalassiosira sp. (CNS00561) and T. oceanica were different from that of other Thalassiosira species. Additionally, endosymbiotic gene transfers (EGT) were found to occur in the evolution of Thalassiosira cpDNAs. Furthermore, genomic regions of cpDNAs were found to be highly variable, which could be used to construct molecular markers for distinguishing Thalassiosira species with high resolution and high specificity. This study also demonstrated that Thalassiosira species emerged roughly around 51 MYA and diversified 17–28 MYA. Thalassiosira cpDNAs are not only valuable as super-barcode for phylogenetic analysis, but also important for functional and evolutionary analysis of diatoms.

Ant assemblages (Hymenoptera: Formicidae) from areas under the direct influence of two small hydropower plants in Brazil

Current energy production has been the subject of studies on environmental impacts and the need to adequately understand that the relationship to biodiversity loss is growing. One of the ways of assessing environmental changes is the use of bioindicator species, and ants represent an alternative in this regard. This study aimed to evaluate ant assemblages occurring in different environments in areas under the direct influence of two small hydropower plants (SHPP). Sampling was carried out using pitfall traps in forest and agricultural fragments, as well as pasture areas, along the Andrada River, municipality of Cascavel, state of Paraná, in July 2016 and March 2017. The sampled ant assemblages were evaluated for richness, abundance, and composition. The rarefaction analysis was used to compare the richness sampled in the two areas under direct influence. Abundance was analyzed based on the number of occurrences. The nonmetric multidimensional scaling (NMDS) was applied to test whether the abundance and composition of ant assemblages differ at the same site when sampled in both seasons. In total, 63 species belonging to 23 genera and 6 subfamilies were identified. The subfamily Myrmicinae was the most speciesrich (S = 25), followed by the subfamily Formicinae (S = 21). The most species-rich genus was Camponotus (S = 15) followed by Pheidole (S =11). A total of 41.3% richness was registered concurrently in the two assemblages. The study contributes to the expansion of knowledge of the ant fauna occurring in the state of Paraná and serves as a basis for monitoring impacts caused by the implementation of SHPP and other developments.

Current knowledge of the family Pompilidae (Hymenoptera: Vespoidea) in Mexico: diversity and geographical distribution.

The family Pompilidae is a little-known insect group in Mexico, which comprises insects known as spider-hunting wasps. This study aimed to review and update the occurrence of pompilids in Mexico and provide information on their geographical distribution. A total of 305 species and 46 genera were compiled, of which 131 species and 11 genera were added to the Pompilidae species list in Mexico. Moreover, we provided data on the geographical distribution of 216 Pompilidae species and highlighted 126 species as registered only from this country, which accounted for 41 % of the total species. The nearctic portion in Mexico is the most studied area, with 203 species, whereas only 96 species are listed from the neotropical region of the country. Four subfamilies were represented: Pompilinae with 161 species, Pepsinae with 128 species, Ceropalinae with ten species, and Notocyphinae with six species. Anoplius was the most species-rich genus with 41 species, and Sericopompilus neotropicalis was the most widely distributed species. The analysis suggests a high diversity of the family Pompilidae and underlines the need to further explore southern areas of Mexico.

Zoogeographical Evaluation of Buprestidae (Coleoptera) Fauna of Turkey and Its Adjacent Countries

The aim of this study is understanding faunistic and zoogeographical composition of the Turkish Buprestidae fauna and determining similarities between Turkey and its adjacent countries. Palaearctic region is handled in nine subregions (Southern Europe, Western Europe, Northern Europe, Eastern Europe, Siberia, Middle East, Middle Asia, Far Eastern Asian and North Africa). Buprestidae fauna of Turkey has 421 species belonging 37 genera and 6 subfamilies according to present literature. Chrysochroinae (130 species) and Buprestinae (132 species) are the most specios subfamilies in Turkey. The genera Anthaxia (103 species) and Sphenoptera (82 species) were the most species-rich genera. The fauna of Greece have highest of similarity with Buprestidae fauna of Turkey. Acmaeoderella flavofasciata (Piller and Mitterpacher, 1783), Capnodis cariosa (Pallas, 1776), Capnodis porosa (Klug, 1829), Capnodis tenebricosa (Olivier, 1790), Capnodis tenebrionis (Linnaeus, 1761), Anthaxia anatolica Chevrolat, 1838, Chrysobothris affinis (Fabricius, 1794), Melanophila cuspidata (Klug, 1829), Trachypteris picta (Pallas, 1773), Coraebus rubi (Linnaeus, 1767) and Meliboeus parvulus Küster, 1852 are existing in Turkey and all adjacent countries.

Phylogeny of the Neotropical element of the Randia clade (Gardenieae, Rubiaceae, Gentianales)

Background and aims – Generic limits of the tropical tribe Gardenieae (Ixoroideae, Rubiaceae) have partly remained unsettled. We produced a new phylogeny of the Randia clade, with emphasis on its Neotropical clade comprising five genera (Casasia, Randia, Rosenbergiodendron, Sphinctanthus, and Tocoyena). The result was subsequently used to evaluate and discuss: a) the respective monophyly of the above-mentioned genera and their interrelationships; b) relationships within Tocoyena and the evolutionary relevance of its subgeneric classification; and c) the monophyly of the morphologically variable T. formosa.Material and methods – We examined the phylogeny of the Randia clade based on maximum likelihood and Bayesian analyses of sequence data from two nuclear (ETS and Xdh) and two plastid (petB-petD and trnT-F) DNA regions from 59 individuals (including seven representatives from the remaining Ixoroideae).Key results – The Neotropical clade of the Randia clade comprises three major lineages, the Randia armata subclade, the Randia-Casasia subclade and the Rosenbergiodendron subclade. Neither Casasia nor Randia is monophyletic. Tocoyena is sister to Rosenbergiodendron + Sphinctanthus and is subdivided into three lineages: the Tocoyena pittieri group, the Tocoyena guianensis group, and the core Tocoyena. Tocoyena williamsii is paraphyletic with respect to T. pittieri. Tocoyena formosa is polyphyletic and should be re-circumscribed.Conclusions – Our results demonstrate the monophyly of each of the relatively species-poor genera Rosenbergiodendron, Sphinctanthus, and Tocoyena, and confirm their close affinity. The serial classification of Tocoyena does not reflect the evolutionary history of the genus. The paraphyly of T. williamsii with respect to T. pittieri, together with their morphological similarities and geographic distributions, support the inclusion of the former in the latter. Our study calls for additional phylogenetic work on Casasia and the more species-rich genus Randia. While the respective monophyly of both genera is rejected here, future work with a broader representation of Randia is needed.

Comparative Analysis of Chloroplast Genomes of Seven Chaetoceros Species Revealed Variation Hotspots and Speciation Time.

Chaetoceros is a species-rich diatom genus with broad distribution and plays an important role in global carbon cycle and aquatic ecosystems. However, genomic information of Chaetoceros species is limited, hindering advanced researches on Chaetoceros biodiversity and their differential impact on ecology. In this study, we constructed full-length chloroplast genomes (cpDNAs) for seven Chaetoceros species, including C. costatus, C. curvisetus, C. laevisporus, C. muelleri, C. pseudo-curvisetus, C. socialis, and C. tenuissimus. All of these cpDNAs displayed a typical quadripartite structure with conserved genome arrangement and specific divergence. The sizes of these cpDNAs were similar, ranging from 116,421 to 119,034 bp in size, and these cpDNAs also displayed similar GC content, ranging from 30.26 to 32.10%. Despite extensive synteny conservation, discrete regions showed high variations. Divergence time estimation revealed that the common ancestor of Chaetoceros species, which formed a monophyletic clade at approximately 58 million years ago (Mya), split from Acanthoceras zachariasii at about 70 Mya. The availability of cpDNAs of multiple Chaetoceros species provided valuable reference sequences for studying evolutionary relationship among Chaetoceros species, as well as between Chaetoceros species and other diatom species.

Incongruent phylogenies and their implications for the study of diversification, taxonomy, and genome size evolution of Rhododendron.

Classification of taxa depends on the quality of inferred phylogenies. Rhododendron, a highly species-rich genus (>1156 species) of woody plants, has a highly debated infrageneric classification, due to its huge diversity, homoplasy in key characters, and incongruence among data sets. We provide a broad coverage of representative species to resolve Rhododendron infrageneric phylogeny and highlight the areas of incongruence. We further investigate the effect of polyploidy and genome size evolution on diversification of Rhododendron. We generated two plastid and two nuclear loci for 260 Rhododendron species. We analyzed the loci separately as well as concatenated, utilizing both likelihood and Bayesian methods. We tested incongruence both among the data sets and with previous studies. We estimated genome sizes for 125 species through flow cytometry. Our results suggest stronger support for larger subgenera; however, the smaller subgenera pose several problems; for example, R. tomentosum (former genus Ledum) occupies incongruent positions based on different DNA regions. The main shift to higher diversification in the genus occurs in the Himalayan/Southeast Asian clade of R. subg. Hymenanthes. We found that polyploidy occurs in almost all subgenera but most frequently within R. subg. Rhododendron sections Rhododendron and Schistanthe. We endorse the recognition of five major clades at the subgeneric level, but a number of species cannot be confidently assigned to these clades due to incongruency. With regard to genome size evolution, results support previous reports that genome sizes of tropical plants are lower than those of colder and temperate regions and that genome downsizing promotes diversification.

Chromosome numbers of eight Carex taxa in Korea (Cyperaceae)

In the flora of Korea, Carex L. is one of the most species-rich genera. Among nearly 157 Carex taxa, less than 30 have had their chromosome numbers reported. We report the meiotic chromosome numbers of eight Carex taxa from Korean populations, which include the first count for C. accrescens Ohwi (n = 37II) and the first chromosome investigations of Korean populations for three taxa: C. bostrychostigma Maxim. (n = 22II), C. lanceolata Boott (n = 36II), and C. paxii Kük. (n = 38II). In most species, chromosome counts observed in the study are included within the variation ranges of previous chromosome numbers. However, C. bostrychostigma Maxim. (n = 22II) and C. planiculmis Kom. (n = 29II) are assigned new chromosome numbers. Carex is known to have holocentric chromosomes, lacking visible primary constrictions and exhibiting great variance in its chromosome number. Further investigations of the diversity of Carex chromosomes will provide basic information with which to understand the high species diversity of the genus.

New phenotypic synapomorphies delimit three molecular-based clades of New World direct-developing frogs (Amphibia: Anura: Brachycephaloidea)

AbstractBrachycephaloidea (composed of 1183 species) is the most diverse superfamily of amphibians. In recent years, molecular techniques utilizing genetic markers have significantly improved our understanding of the phylogeny of this superfamily. However, with the expansion of molecular techniques, phenotypic characters have received increasingly less attention. In an effort to highlight the contributions that phenotypic characters can make to understanding the phylogeny of Brachycephaloidea, we studied novel characters from pelvic and thigh musculature and digital discs on fingers. On this basis, we provide new phenotypic synapomorphies to recognize three clades previously recognized solely on the basis of DNA. The first two synapomorphies, related to the origins of the m. iliacus externus and m. tensor fasciae latae, diagnose Ceuthomantis and Phrynopus, respectively. The third synapomorphy, related to the relative size of the disc on finger I, diagnoses the Pristimantis conspicillatus species group, which is the largest species group within the species-rich genus Pristimantis. We conclude that phenotypic data are a valuable source of evidence in testing phylogenetic hypotheses of Brachycephaloidea and emphasize the need to reassess all phenotypic characters previously used in brachycephaloid taxonomy to delimit them objectively as transformation series and include them in total evidence analyses.

BIG-EYED BUGS OF THE SOLOMON ISLANDS: TAXONOMY, ECOLOGICAL AND EVOLUTIONARY SIGNIFICANCE (HETEROPTERA: LYGAEOIDEA: GEOCORIDAE)

ABSTRACT The genus Germalus Stål, 1862 is the second most species-rich genus of the predaceous true bug subfamily Geocorinae Baerensprung, 1860 (commonly known as big-eyed bugs), distributed in the tropical regions of the Old World. We report the presence of the genus for the first time from the Solomon Islands, describing three new species: G. scabrus sp. nov., G. t-nigrum sp. nov. and G. redeii sp. nov. Label data of the specimens suggest predaceous feeding of the newly described species, supporting previous findings on the possible importance of the genus for plant protection. Investigation on the placement of these newly described taxa within the genus highlighted the presence of morphologically coherent taxon complexes in the Pacific Region with a well-defined distribution area. To summarise, the discovery and description of three new representatives of the genus Germalus contribute to the taxonomic, ecological and evolutionary knowledge of this long-neglected big-eyed bug taxon.

Redescription of Biacetabulum giganteum Hunter, 1929 (Cestoda: Caryophyllidea), description of two new, closely related species from suckers (Catostomidae) in North America, and a critical review of host specificity of species of Biacetabulum Hunter, 1927

Morphological and molecular evaluation of tapeworms of the order Caryophyllidea from suckers (Cypriniformes: Catostomidae) in North America made it possible to redescribe the insufficiently known and rare species Biacetabulum giganteum Hunter, 1929, based on specimens from the type host, small mouth buffalo, Ictiobus bubalus. This cestode is mainly typified by an elongate bottle-shaped body with a narrow, long neck region distinctly separating a relatively large scolex with deep loculi and a sharply widening body. Molecular phylogenetic analysis based on sequences of the large subunits of the nuclear ribosomal RNA genes (lsrDNA or 28S rDNA) placed B. giganteum in a clade called herein the B. giganteum-species complex, which also includes two morphologically similar new species. Biacetabulum magdae sp. nov. is described from the blacktail redhorse, Moxostoma poecilurum (type host), and the spotted sucker, Minytrema melanops, in Mississippi, USA. It differs from B. giganteum by the scolex with a weakly developed apical disc and shallow median and lateral loculi. Biacetabulum johni sp. nov. is described from Minytrema melanops (type host) in Florida and Moxostoma poecilurum in Mississippi, USA. Biacetabulum johni sp. nov. can be distinguished from B. magdae sp. nov. by a smaller size of the body (5–7 mm versus 10–12 mm) and a relatively longer neck, with the first vitelline follicles beginning at about the mid-length of the body in B. johni (versus at the first third or fourth of the body in B. magdae). With two new species described herein, Biacetabulum becomes the most species-rich genus of caryophyllidean tapeworms, with a total of 14 nominal species known to date (recently described B. hypentelii is synonymized with B. longicollum based on newly generated molecular data). Host specificity of species of Biacetabulum Hunter, 1927 was critically reviewed and it is shown that the actual host specificity is considerably higher than that reported in the literature. http://zoobank.org/urn:lsid:zoobank.org:pub:lsid:zoobank.org:pub:ABF5446A-F170-4CA0-9AF7-D5234BD71139

Floral morphogenesis of Celtis species: implications for breeding system and reduced floral structure.

Celtis is the most species-rich genus of Cannabaceae, an economically important family. Celtis species have been described as wind-pollinated and andromonoecious. However, the andromonoecy of Celtis has been debated because there are reports of monoclinous flowers with non-opening anthers on short filaments. Our objective was to study the floral morphogenesis of Celtis to establish the breeding system and to better understand the developmental patterns that lead to the formation of reduced flowers in the genus. Flowers and floral buds of Celtis species were studied using scanning electron microscopy, high-resolution x-ray computed tomography, and light microscopy. All flowers initiate stamens and carpels during early floral development, but either stamens or carpels abort during later stages. Thus, at anthesis, flowers are either functionally pistillate or functionally staminate. In pistillate flowers, stamens abort late and become staminodes with normal-looking anthers. These anthers have no functional endothecium and, in most of the species studied, produce no viable pollen grains. The gynoecium is pseudomonomerous, and its vascularization is similar in the sampled species. In staminate flowers, the gynoecium aborts early resulting in small pistillodes. No vestiges of petals were found. The species studied are monoecious and not andromonoecious as described earlier. The absence of petals, the carpel and stamen abortion, and the pseudomonomerous gynoecium result in the reduced flowers of Celtis species. The use of high-resolution x-ray computed tomography was essential for a more accurate interpretation of ovary vascularization, confirming the pseudomonomerous structure of the gynoecium.