First phylogeny of predatory flower flies (Diptera, Syrphidae, Syrphinae) using mitochondrial COI and nuclear 28S rRNA genes: conflict and congruence with the current tribal classification

Phylogenomic analysis of Syrphoidea (Diptera: Syrphidae, Pipunculidae) based on the expanded mitogenomic data

The mitochondrial genome has become the most widely used genomic resource in resolving the insect phylogenetic relationships. In this study, we assess the interrelationships among the syrphid and pipunculid members of Syrphoidea using mitochondrial genome sequences of 152 taxa, 9 of which are newly reported and three are assembled from the existing transcriptome data. The Pipunculidae was found to be deeply nested members of Schizophora, which resulted in a nonmonophyletic Syrphoidea. In the monophyletic Syrphidae, unequivocal robust support was found for Microdontinae as the sister group of all other Syrphidae. The subfamily Eristalinae was nonmonophyletic. The Pipizinae was recovered as the sister group to the Syrphinae, albeit with strong support. As a whole, our results are concord with previously established hypotheses on Syrphoidea from the genome scale data. The mitochondrial genomes were successful in producing a robustly supported phylogenetic framework for the Syrphoidea.

An updated checklist of the hoverflies (Diptera: Syrphidae) of Slovenia

This paper is an updated checklist of the hoverflies of Slovenia. Since the last checklist of 274 species published by de Groot & Govedič in 2008, a large number of additional specimens have been collected and studied. In the present study, 42 species are reported for the first time for the Slovenian hoverfly fauna. Sphegina sublatifrons Vujić, 1990 is deleted from the Slovenian list. In total, 362 species from 77 genera are reported. According to the IUCN European Red List of Hoverflies, 29 species are classified as Endangered, 9 as Vulnerable, 19 as Near Threatened, 302 as Least Concern and 3 as Data Deficient. The distribution of species per region in Slovenia is presented. With 243 species, Upper Carniola hosts the largest number of registered species, followed by Central Slovenia (233 spp.), Gorizia (230 spp.), Savinja and Littoral Inner-Carniola (both with 173 spp.), Coastal-Karst (133 spp.), Southeast Slovenia (71 spp.), Drava (60 spp.), Carinthia (56 spp.), Lower Sava (52 spp.), Mura (47 spp.) and Central Sava (8 spp.). A significant increase in the number of new records has been noted in recent decades, and the possible reasons for this trend are also discussed here.

The phylogeny and evolutionary ecology of hoverflies (Diptera: Syrphidae) inferred from mitochondrial genomes

Hoverflies (Diptera: Syrphidae) are a diverse group of pollinators and a major research focus in ecology, but their phylogenetic relationships remain incompletely known. Using a genome skimming approach we generated mitochondrial genomes for 91 species, capturing a wide taxonomic diversity of the family. To reduce the required amount of input DNA and overall cost of the library construction, sequencing and assembly was conducted on mixtures of specimens, which raises the problem of chimera formation of mitogenomes. We present a novel chimera detection test based on gene tree incongruence, but identified only a single mitogenome of chimeric origin. Together with existing data for a final set of 127 taxa, phylogenetic analysis on nucleotide and amino acid sequences using Maximum Likelihood and Bayesian Inference revealed a basal split of Microdontinae from all other syrphids. The remainder consists of several deep clades assigned to the subfamily Eristalinae in the current classification, including a clade comprising the subfamily Syrphinae (plus Pipizinae). These findings call for a re-definition of subfamilies, but basal nodes had insufficient support to allow such action. Molecular-clock dating placed the origin of the Syrphidae crown group in the mid-Cretaceous while the Eristalinae-Syrphinae clade likely originated near the K/Pg boundary. Transformation of larval life history characters on the tree suggests that Syrphidae initially had sap feeding larvae, which diversified greatly in diet and habitat association during the Eocene and Oligocene, coinciding with the diversification of angiosperms and the evolution of various insect groups used as larval host, prey, or mimicry models. Mitogenomes proved to be a powerful phylogenetic marker for studies of Syrphidae at subfamily and tribe levels, allowing dense taxon sampling that provided insight into the great ecological diversity and rapid evolution of larval life history traits of the hoverflies.

Attracted to feed, not to be fed upon – on the biology of Toxomerus basalis (Walker, 1836), the kleptoparasitic ‘sundew flower fly’ (Diptera: Syrphidae)

The complete life history of the kleptoparasitic ‘sundew flower fly’, Toxomerus basalis, is presented and illustrated. Adults of this species are photographed alive for the first time, including video recordings of larval and adult behaviour. Adult flies of both sexes visit Drosera (sundews) and show territorial behaviour around the plants, avoiding the dangerous sticky traps and demonstrating recognition of their larval host plant. Females lay eggs directly on non-sticky parts of the Drosera host plants, such as on the lower surface of the leaves and flower stalks, but apparently also on other plants growing in close proximity with the sundews.

Disney RH, Maleki-Ravasan N. The scuttle flies (Diptera: Phoridae) of Iran with the description of Mahabadphora aesthesphora as a new genus and species

Scuttle flies (Diptera: Phoridae) are mega-diverse and often synanthropic insects that play superb roles in various ecosystems. Identification of this group of insects is challenging due to their small size, morphological identification difficulties, niche diversity, and lack of taxonomic keys. To pave the way, an in-depth investigation was directed toward the scuttle flies in Iran using morphological and molecular data. A dichotomous key was also developed to identify the genus and species of the phorids reported in the country. The faunistic findings revealed the presence of about 22,000 (13,903 male and 8,097 female) phorid materials organized into 11 genera. Megaselia species (n = 13768), made up about 99% of the specimens studied. Moreover, 71 morphologically defined species belonging to nine genera were molecularly characterized using COI, 28S rRNA, and Arginine kinase datasets. Excluding four Megaselia Rondani, 1856 species, our results specified that morphologically delimited species were in agreement with the molecular analyses inferred from the COI/28S rRNA and COI/Arginine kinase sequences with genetic distances and phylogenetic trees. According to the results of the present study and previously published data, the Phoridae recorded for Iran are a total of 97 species that are ordered in 13 genera and three subfamilies, including Chonocephalinae, Metopininae and Phorinae. By comparing the known world phorid genera, a new monotypic genus of scuttle flies, Mahabadphora aesthesphora gen. nov., sp. nov., was identified based on its morphological and molecular characteristics and included in an updated key. Our results could comprehensively determine the taxonomic status of scuttle flies in Iran, scrutinize their phylogenetic structures and facilitate their identification.

A multigene phylogeny of the eristaline flower flies (Diptera: Syrphidae), with emphasis on the subtribe Criorhinina

We present the first multigene phylogeny focused on Eristalinae (Diptera: Syrphidae) utilizing a dataset containing 120 flower fly species from across all four subfamilies and representing 13 out of 16 tribes. Eight genes were used in the construction of the phylogeny: mitochondrial cytochrome c oxidase subunit I and the nuclear genes 28S ribosomal DNA, Alanylt RNA Synthetase, the carbamoyl phosphate synthase domain of CAD, Period, RNA-binding Protein 15 (RBP–15, 5’), Casein Kinase 1 and TULP for a total of ~6.7 kB of data. Eristalinae is recovered as paraphyletic with strong support for the elevation of Cerioidini, Merodontini and Volucellini to subfamilial status. Deineches, Flukea and Malometasternum render Criorhinina paraphyletic with respect to the type genus Criorhina. A clade with Criorhina, Matsumyia and Sphecomyia is strongly supported. The generic concept of Criorhina is paraphyletic, while Sphecomyia is monophyletic and Matsumyia is monophyletic but requires expansion. Evidence supports the resurrection of Romaleosyrphus and the creation of new genera. Criorhinina (stat. rev.) is restricted to contain Criorhina, Matsumyia, Romaleosyrphus and Sphecomyia. Thirteen changes to the higher classification of Syrphidae are proposed.

Key long-proboscid fly pollinator overlooked: morphological and molecular analyses reveal a new Prosoeca (Nemestrinidae) species

Long-proboscid nemestrinid flies are keystone pollinators of dozens of Southern African plants and, consequently, their taxonomic status might have important consequences for insect and plant conservation. We focus on Prosoeca peringueyi, considered to be a single, morphologically variable species, upon which a guild of ~28 plants in the winter rainfall region depends for pollination. We quantified morphological variation and established whether it was associated with genetic variation within and among sites. Phylogenetic analyses of the mitochondrial COI gene revealed two well-supported clades. One clade contains long-proboscid individuals that conform morphologically to the holotype of P. peringueyi. The sister clade contains individuals that frequently occur sympatrically with P. peringueyi and have shorter proboscides, with additional diagnostic characters that set it apart from P. peringueyi. A haplotype analysis based on nuclear ribosomal 28S DNA sequences of a subset of individuals corroborated these results. Based on our results, we propose the recognition of two species: P. peringueyi and Prosoeca torquata sp. nov., which is described here. Future research is required to quantify the interaction networks of these two fly species and the plant guilds with which they interact, to facilitate conservation in the global biodiversity hotspot where they occur.

Description of six new large species of Argentinomyia Lynch-Arribálzaga, 1891 and redescription of Talahua fervida (Fluke, 1945) (Diptera, Syrphidae, Syrphinae)

The morphological similarities between five new large Argentinomyia species and Talahua fervida Fluke are characterized and presented. Six new species of Argentinomyia (10-12 mm long) are described: Argentinomyia andina Montoya & Wolff, sp. nov. (Colombia), Argentinomyia choachi Montoya, sp. nov. (Colombia), Argentinomyia quimbaya Montoya & Wolff, sp. nov. (Colombia), Argentinomyia huitepecensis Montoya, sp. nov. (México), Argentinomyia puntarena Montoya, sp. nov. (Costa Rica), and Argentinomyia talamanca Thompson, sp. nov. (Costa Rica). The genus Talahua Fluke is re-diagnosed and, Talahua fervida redescribed. A taxonomic key and a comparison of diagnostic characters are presented. Photographs of head, abdominal and wing maculae patterns, as well as illustrations of male genitalia are provided for species identification.

A world review of reported myiases caused by flower flies (Diptera: Syrphidae), including the first case of human myiasis from Palpada scutellaris (Fabricius, 1805)

Rat-tailed larvae of the syrphid species Palpada scutellaris (Fabricius, 1805) are documented causing an enteric human myiasis in Costa Rica. This is the first time that the genus Palpada is recorded as a human myiasis agent. We report a 68-year-old woman with intestinal pain and bloody diarrhea with several live Palpada larvae present in the stool. Using molecular techniques (DNA barcodes) and both electronic and optical microscopy to study the external morphology, the preimaginal stages of the fly were unambiguously identified. An identification key to all syrphid genera actually known as agents of human and animal myiases is provided for larvae, puparia, and adults. Moreover, a critical world review of more than 100 references of Syrphidae as myiasis agents is also given, with emphasis on the species with rat-tailed larvae.

Multiplex PCR Method for Discriminating Between Sphaerophoria macrogaster (Diptera: Syrphidae) and Sphaerophoria indiana (Diptera: Syrphidae)

Hoverflies are potential candidates for biological control of aphid populations; however, identification of closely related hoverfly species by using morphological characteristics is quite difficult. For instance, adults of Sphaerophoria macrogaster (Thomson) (Diptera: Syrphidae)-the predominant species early in the vegetable production season in Japan-are morphologically indistinguishable from those of Sphaerophoria indiana Bigot (Diptera: Syrphidae) without comparison of the male genitalia. Here, we investigated genetic variation of the mitochondrial cytochrome c oxidase subunit I (COI) gene of the two species by DNA sequencing and developed a multiplex PCR method for differentiating the two species. Alignment of COI sequences revealed 1.2% nucleotide variance between the two species. The COI sequence of S. macrogaster collected from Japan was 99.8% identical to those of S. macrogaster collected from India. The COI sequence of S. indiana collected from Japan was 100% identical to that of Sphaerophoria philanthus (Meigen) (Diptera: Syrphidae) collected from Canada. The sizes of the multiplex PCR products differentiated following gel electrophoresis were 162 bp for S. macrogaster and 607 bp for S. macrogaster and S. indiana. The accuracy rate of multiple PCR was 100%. Use of this method will facilitate further research into the characteristics of hoverflies and will improve the efficacy of biological control using hoverflies on vegetable crops.

Checklist of the flower flies of Ecuador (Diptera, Syrphidae)

Syrphidae is one of the most speciose families of true flies, with more than 6,100 described species and worldwide distribution. They are important for humans acting as crucial pollinators, biological control agents, decomposers, and bioindicators. One third of its diversity is found in the Neotropical Region, but the taxonomic knowledge for this region is incomplete. Thus, taxonomic revisions and species checklists of Syrphidae in the Neotropics are the highest priority for biodiversity studies. Therefore, we present the first checklist of Syrphidae for Ecuador based on literature records, and provide as well the original reference for the first time species citations for the country. A total of 201 species were recorded for Ecuador, with more than 600 records from 24 provinces and 237 localities. Tungurahua, Pastaza, and Galápagos were the best sampled provinces. Although the reported Ecuadorian syrphid fauna only comprises 11.2 % of the described Neotropical species, Ecuador has the third highest flower fly diversity density after Costa Rica and Suriname. These data indicate the high species diversity for this country in such small geographic area.

Mitochondrial genomes of the hoverflies Episyrphus balteatus and Eupeodes corollae (Diptera: Syrphidae), with a phylogenetic analysis of Muscomorpha

The hoverflies Episyrphus balteatus and Eupeodes corollae (Diptera: Muscomorpha: Syrphidae) are important natural aphid predators. We obtained mitochondrial genome sequences from these two species using methods of PCR amplification and sequencing. The complete Episyrphus mitochondrial genome is 16,175 bp long while the incomplete one of Eupeodes is 15,326 bp long. All 37 typical mitochondrial genes are present in both species and arranged in ancestral positions and directions. The two mitochondrial genomes showed a biased A/T usage versus G/C. The cox1, cox2, cox3, cob and nad1 showed relatively low level of nucleotide diversity among protein-coding genes, while the trnM was the most conserved one without any nucleotide variation in stem regions within Muscomorpha. Phylogenetic relationships among the major lineages of Muscomorpha were reconstructed using a complete set of mitochondrial genes. Bayesian and maximum likelihood analyses generated congruent topologies. Our results supported the monophyly of five species within the Syrphidae (Syrphoidea). The Platypezoidea was sister to all other species of Muscomorpha in our phylogeny. Our study demonstrated the power of the complete mitochondrial gene set for phylogenetic analysis in Muscomorpha.

Anchored enrichment dataset for true flies (order Diptera) reveals insights into the phylogeny of flower flies (family Syrphidae)

BACKGROUND

Anchored hybrid enrichment is a form of next-generation sequencing that uses oligonucleotide probes to target conserved regions of the genome flanked by less conserved regions in order to acquire data useful for phylogenetic inference from a broad range of taxa. Once a probe kit is developed, anchored hybrid enrichment is superior to traditional PCR-based Sanger sequencing in terms of both the amount of genomic data that can be recovered and effective cost. Due to their incredibly diverse nature, importance as pollinators, and historical instability with regard to subfamilial and tribal classification, Syrphidae (flower flies or hoverflies) are an ideal candidate for anchored hybrid enrichment-based phylogenetics, especially since recent molecular phylogenies of the syrphids using only a few markers have resulted in highly unresolved topologies. Over 6200 syrphids are currently known and uncovering their phylogeny will help us to understand how these species have diversified, providing insight into an array of ecological processes, from the development of adult mimicry, the origin of adult migration, to pollination patterns and the evolution of larval resource utilization.

RESULTS

We present the first use of anchored hybrid enrichment in insect phylogenetics on a dataset containing 30 flower fly species from across all four subfamilies and 11 tribes out of 15. To produce a phylogenetic hypothesis, 559 loci were sampled to produce a final dataset containing 217,702 sites. We recovered a well resolved topology with bootstrap support values that were almost universally >95 %. The subfamily Eristalinae is recovered as paraphyletic, with the strongest support for this hypothesis to date. The ant predators in the Microdontinae are sister to all other syrphids. Syrphinae and Pipizinae are monophyletic and sister to each other. Larval predation on soft-bodied hemipterans evolved only once in this family.

CONCLUSIONS

Anchored hybrid enrichment was successful in producing a robustly supported phylogenetic hypothesis for the syrphids. Subfamilial reconstruction is concordant with recent phylogenetic hypotheses, but with much higher support values. With the newly designed probe kit this analysis could be rapidly expanded with further sampling, opening the door to more comprehensive analyses targeting problem areas in syrphid phylogenetics and ecology.

Where Is My Food? Brazilian Flower Fly Steals Prey from Carnivorous Sundews in a Newly Discovered Plant-Animal Interaction

A new interaction between insects and carnivorous plants is reported from Brazil. Larvae of the predatory flower fly Toxomerus basalis (Diptera: Syrphidae: Syrphinae) have been found scavenging on the sticky leaves of several carnivorous sundew species (Drosera, Droseraceae) in Minas Gerais and São Paulo states, SE Brazil. This syrphid apparently spends its whole larval stage feeding on prey trapped by Drosera leaves. The nature of this plant-animal relationship is discussed, as well as the Drosera species involved, and locations where T. basalis was observed. 180 years after the discovery of this flower fly species, its biology now has been revealed. This is (1) the first record of kleptoparasitism in the Syrphidae, (2) a new larval feeding mode for this family, and (3) the first report of a dipteran that shows a kleptoparasitic relationship with a carnivorous plant with adhesive flypaper traps. The first descriptions of the third instar larva and puparium of T. basalis based on Scanning Electron Microscope analysis are provided.

First records of Pseudodoros nigricollis Becker (Diptera: Syrphidae) from Cyprus

BACKGROUND

The hoverfly Pseudodoros nigricollis Becker, 1903 is a rarely collected species, of which information on its distribution and ecology is poorly understood.

NEW INFORMATION

In this paper the first records of the hoverfly Pseudodoros nigricollis from Cyprus are provided and discussed. The discovery indicates that this Afrotropical species is approaching the European continent. Short notes on the habitat in which it has been collected are provided. The relationship with the mealy plum aphid Hyalopterus pruni is discussed. Clues on further research are given.

Australian Allograpta Osten Sacken (Diptera, Syrphidae)

Allograptaterraenovae sp. n. and Allograptanotiale sp. n. are described from Australia. Notes on the Australian species of Allograpta and an identification key to them are also given. The lectotype of Allograptajavana Wiedemann is designated, and the species Syrphuspallidus Bigot is synonymized under Allograptaaustralensis (Schiner).

The relationship between morphological and behavioral mimicry in hover flies (Diptera: Syrphidae)

Palatable (Batesian) mimics of unprofitable models could use behavioral mimicry to compensate for the ease with which they can be visually discriminated or to augment an already close morphological resemblance. We evaluated these contrasting predictions by assaying the behavior of 57 field-caught species of mimetic hover flies (Diptera: Syrphidae) and quantifying their morphological similarity to a range of potential hymenopteran models. A purpose-built phylogeny for the hover flies was used to control for potential lack of independence due to shared evolutionary history. Those hover fly species that engage in behavioral mimicry (mock stinging, leg waving, wing wagging) were all large wasp mimics within the genera Spilomyia and Temnostoma. While the behavioral mimics assayed were good morphological mimics, not all good mimics were behavioral mimics. Therefore, while the behaviors may have evolved to augment good morphological mimicry, they do not advantage all good mimics.

A comparative analysis of the evolution of imperfect mimicry

Although exceptional examples of adaptation are frequently celebrated, some outcomes of natural selection seem far from perfect. For example, many hoverflies (Diptera: Syrphidae) are harmless (Batesian) mimics of stinging Hymenoptera. However, although some hoverfly species are considered excellent mimics, other species bear only a superficial resemblance to their models and it is unclear why this is so. To evaluate hypotheses that have been put forward to explain interspecific variation in the mimetic fidelity of Palearctic Syrphidae we use a comparative approach. We show that the most plausible explanation is that predators impose less selection for mimetic fidelity on smaller hoverfly species because they are less profitable prey items. In particular, our findings, in combination with previous results, allow us to reject several key hypotheses for imperfect mimicry: first, human ratings of mimetic fidelity are positively correlated with both morphometric measures and avian rankings, indicating that variation in mimetic fidelity is not simply an illusion based on human perception; second, no species of syrphid maps out in multidimensional space as being intermediate in appearance between several different hymenopteran model species, as the multimodel hypothesis requires; and third, we find no evidence for a negative relationship between mimetic fidelity and abundance, which calls into question the kin-selection hypothesis. By contrast, a strong positive relationship between mimetic fidelity and body size supports the relaxed-selection hypothesis, suggesting that reduced predation pressure on less profitable prey species limits the selection for mimetic perfection.

The diversity of flower flies (Diptera: syrphidae) in Colombia and their neotropical distribution

In Colombia, like most Neotropical countries, faunistic studies on flower flies have been occasional and most of them have been primarily focused on taxonomy. Colombia is the second-most species-rich country in flower fly diversity in the Neotropics after Brazil, and has one of the highest numbers of species per unit area (2.49 per 10,000 km²), based on a review of literature and national collections. Including new data presented here, a total of 47 genera and 300 species are recorded in Colombia. The genera Scaeva Fabricius and Lycastrirhyncha Bigot, as well as 101 species are recorded here for the first time. The altitudinal range and the distribution of the flower fly genera in Colombia are presented. A preliminary comparison of the fauna of Colombia with that of other Neotropical countries is given. A historical perspective is also provided in order to illustrate how Colombian Syrphidae knowledge has progressed over the last 168 years. Information presented here will be useful for ongoing and future biodiversity research as well as conservation projects on Syrphidae in the Neotropical region.

Is the mega-diverse genus Ocyptamus (Diptera, Syrphidae) monophyletic? Evidence from molecular characters including the secondary structure of 28S rRNA

Phylogenetic relationships between two New World Syrphinae taxa (Diptera, Syrphidae), i.e. the highly diverse genus Ocyptamus and the large genus Toxomerus, were analysed based on molecular characters. The monophyly of both taxa was tested and the taxonomic status of included subgenera and species groups was examined. Toxomerus constitutes the monogeneric tribe Toxomerini with more than 140 described species, while Ocyptamus (tribe Syrphini) is a very diverse genus (over 300 spp.) with multiple recognised subgenera and species groups. Sequence data from three gene regions were used: the mitochondrial protein-coding gene cytochrome c oxidase subunit I (COI) and the nuclear 28S and 18S ribosomal RNA genes. The secondary structure of two expansion segments (D2, D3) of the ribosomal 28S RNA gene is presented for the family Syrphidae and used for the first time in a multiple sequence alignment. Molecular data were analysed using parsimony, maximum likelihood and Bayesian inference. Toxomerus was always recovered as monophyletic within Ocyptamus, and relationships to other New World taxa such as Salpingogaster (Eosalpingogaster) were well-supported. Only the subgenera and species groups of Ocyptamus were consistently recovered as monophyletic lineages, thus the apparent non-monophyly of Ocyptamus demands reclassification of this clade.

An evaluation of phylogenetic informativeness profiles and the molecular phylogeny of diplazontinae (Hymenoptera, Ichneumonidae)

How to quantify the phylogenetic information content of a data set is a longstanding question in phylogenetics, influencing both the assessment of data quality in completed studies and the planning of future phylogenetic projects. Recently, a method has been developed that profiles the phylogenetic informativeness (PI) of a data set through time by linking its site-specific rates of change to its power to resolve relationships at different timescales. Here, we evaluate the performance of this method in the case of 2 standard genetic markers for phylogenetic reconstruction, 28S ribosomal RNA and cytochrome oxidase subunit 1 (CO1) mitochondrial DNA, with maximum parsimony, maximum likelihood, and Bayesian analyses of relationships within a group of parasitoid wasps (Hymenoptera: Ichneumonidae, Diplazontinae). Retrieving PI profiles of the 2 genes from our own and from 3 additional data sets, we find that the method repeatedly overestimates the performance of the more quickly evolving CO1 compared with 28S. We explore possible reasons for this bias, including phylogenetic uncertainty, violation of the molecular clock assumption, model misspecification, and nonstationary nucleotide composition. As none of these provides a sufficient explanation of the observed discrepancy, we use simulated data sets, based on an idealized setting, to show that the optimum evolutionary rate decreases with increasing number of taxa. We suggest that this relationship could explain why the formula derived from the 4-taxon case overrates the performance of higher versus lower rates of evolution in our case and that caution should be taken when the method is applied to data sets including more than 4 taxa.