DNA Barcoding to Improve the Taxonomy of the Afrotropical Hoverflies (Insecta: Diptera: Syrphidae)

The identification of Afrotropical hoverflies is very difficult because of limited recent taxonomic revisions and the lack of comprehensive identification keys. In order to assist in their identification, and to improve the taxonomy of this group, we constructed a reference dataset of 513 COI barcodes of 90 of the more common nominal species from Ghana, Togo, Benin and Nigeria (W Africa) and added ten publically available COI barcodes from nine nominal Afrotropical species to this (total: 523 COI barcodes; 98 nominal species; 26 genera). The identification accuracy of this dataset was evaluated with three methods (K2P distance-based, Neighbor-Joining (NJ) / Maximum Likelihood (ML) analysis, and using SpeciesIdentifier). Results of the three methods were highly congruent and showed a high identification success. Nine species pairs showed a low ( 0.03) maximum intraspecific K2P distance was observed in eight species and barcodes of these species not always formed single clusters in the NJ / ML analayses which may indicate the occurrence of cryptic species. Optimal K2P thresholds to differentiate intra- from interspecific K2P divergence were highly different among the three subfamilies (Eristalinae: 0.037, Syrphinae: 0.06, Microdontinae: 0.007–0.02), and among the different general suggesting that optimal thresholds are better defined at the genus level. In addition to providing an alternative identification tool, our study indicates that DNA barcoding improves the taxonomy of Afrotropical hoverflies by selecting (groups of) taxa that deserve further taxonomic study, and by attributing the unknown sex to species for which only one of the sexes is known

Taxonomic revision of the Afrotropical hover fly genus Senaspis Macquart (Diptera, Syrphidae)

Open Access Article; Published online: 14 Dec 2020The representatives of the Afrotropical hover fly genus Senaspis Macquart (Diptera) are revised. In total, ten species are recognized. Senaspis apophysata (Bezzi) is herewith placed as junior synonym of S. flaviceps Macquart, S. livida (Bezzi) is herewith placed as junior synonym of S. dentipes (Macquart) and S. griseifacies (Bezzi) is herewith placed as junior synonym of S. haemorrhoa (Gerstaecker). All species are redescribed and an identification key is provided. DNA barcoding analysis (7 species, 64 barcodes) showed that the technique can be used to unambiguously identify the species. The relationships among the different Senaspis species are discussed based on morphological and DNA data

Taxonomic revision of the afrotropical Phytomia gerin-meneville (Diptera: syrphidae)

Open Access Article; Published online: 26 Jun 2020The Afrotropical representatives of the hoverfly genus Phytomia Guérin-Méneville (Diptera) are revised. In total, 19 species are recognized of which three are new to science: Phytomia austeni sp. nov., P. memnon sp. nov., and P. pallida sp. nov. Phytomia neavei Bezzi is considered a junior synonym of P. kroeberi (Bezzi), P. noctilio Speiser a junior synonym of P. pubipennis Bezzi, and P. ephippium Bezzi a junior synonym of P. melas (Bezzi). Lectotypes are designated for the following species: Megaspis bulligera Austen, Megaspis erratica Bezzi, and Megaspis poensis Bezzi. In addition, unpublished lectotype designations are hereby formally published for the following species: Megaspis bullata Loew, Megaspis curta Loew, and Megaspis capito Loew. Phytomia curta (Loew) is considered a valid species, and differentiated from P. natalensis (Macquart). Phytomia fronto Loew is tentatively considered to belong to the genus Simoides Loew. The relationship between the different Phytomia species, as well as the relationship between Phytomia and Simoides, is briefly discussed based on morphological and DNA data

Notes on the Afrotropical hover fly genus Meromacroides Curran (Syrphidae, Eristalinae)

The African endemic hover fly Meromacroides meromacriformis (Bezzi, 1915) (Syrphidae, Eristalinae) was described more than a century ago and its monotypic status established in 1927, but subsequent collections and publications are rare. Only the male has been described and nothing is known about its biology. We re-describe the male, including geographic variation, describe the female for the first time and provide the first DNA barcodes for the species. Despite the large range and observed variations, there is insufficient evidence to describe additional taxa in the genus. Biological observations are presented, which may shed some insight into this rare and enigmatic hover fly, whose known distribution now spans the Afrotropical Region

Loss of genetic variation in a strongly isolated Azorean population of the edible calm, <i>Tapes decussatus</i>

We used allozyme electrophoresis to compare the genetic variation of an introduced and strongly isolated population of the edible clam Tapes decussatus in the Azores (Lagoa de Santo Cristo, Sao Jorge) with populations from the main range of the species (Ria and Thau). Observed and expected heterozygosity values, number of polymorphic loci, and mean number of alleles per locus in the main-range populations fall within the limits reported for T. decussatus and other Venerid clams. In contrast to previous studies on Venerid clams, we observed no heterozygote deficiencies. In the introduced Lagoa population, we observed a strong reduction of allelic diversity and expected heterozygosities and an effective population size of only 5.30. The Lagoa population is only slightly differentiated from populations from the species' main range and may thus be of low "biological value." Exploitation of T. decussatus could therefore be allowed to continue but must follow strict collection guidelines, especially given that only 15% of the area is suitable for exploitation. Otherwise, a unique component of the Azorean fauna that also serves as a fishery resource may be lost

New records of <i>Assiminea grayana</i> Fleming, 1828, <i>Myosotella myosotis</i> (Draparnaud, 1801) and <i>Pisidium subtruncatum</i> Malm, 1855 (Mollusca: Gastropoda, Bivalvia) in the Scheldt estuary

The mollusc fauna of the tidal marshes along the river Scheldt was investigated. To this end, 31 marshes were sampled along a salinity gradient from Berlare (Belgium; freshwater) to Vlissingen (the Netherlands; marine). Our faunistic survey yielded eight new localities for the caenogastropod Assiminea grayana, of which seven in the Belgian part. In the marsh of Doel ("Prosperhaven") we discovered the first inland population of the pulmonate mollusc Myosotella myosotis, a species which in Belgium was hitherto only known from three coastal localities. Finally, additional records of Pisidium subtruncatum for the Scheldt estuary are reported

Systematics of Afrotropical Eristalinae (Diptera: Syrphidae) using mitochondrial phylogenomics

Published online: 11 Jan 2022We examined the phylogeny and intrageneric classification of eristaline hoverfly genera from the Afrotropical Region using mitochondrial genomes. Genome skimming was used to obtain (nearly) full mtDNA and nuclear rDNA (18S, 28S) genomes of 120 museum vouchers from eight genera and 98 species. Phylogenetic reconstructions of mitogenomes and mitogenomes + nuclear rDNA yielded comparable phylogenies while that of rDNA only resulted in poorly resolved phylogenies. Phylogenetic analyses focused on six genera and supported the monophyly of the general Chasmomma Bezzi, Eristalinus Rondani, Mesembrius Rondani and Syritta Le Peletier & Serville, whereas Simoides Loew was not monophyletic and rendered Phytomia Guérin-Méneville paraphyletic. We therefore synonymize Simoides with Phytomia. Within Chasmomma, two species-groups that differ in the colour and the shape of the hind femora (Chasmomma femoratum and Chasmomma nigrum species-groups) were supported. Within Eristalinus, the monophyly of the subgenera Merodonoides Curran and Eristalodes Mik was supported, but not of the subgenus Eristalinus Rondani. Within Syritta, the monophyly of three out of the five species-groups tested was rejected. This approach illustrates the importance of integrative and iterative approaches in taxonomy and shows that genomic data may not only clarify the systematic relationships among hoverfly genera and species, but also offer perspectives into the evolution of morphological and ecological variation within the family

Radular myoglobin as a molecular marker in littorinid systematics (Caenogastropoda)

Radular myoglobin (Mb) was investigated in 288 specimens of 10 littorinid species using vertical polyacrylamide gel electrophoresis (PAGE) and isoelectric focusing (IEF). Within the genus Littorina the two most basal species, L. striata and L. keenae, have Mb patterns that correspond to those of the genera Littoraria and Nodilittorina, while the sibling species L. scutulata and L. plena have identical Mb profiles that consistently differ from those of L. littorea, L. saxatilis, L. compressa and L. areana. In contrast to previous claims, Mb does not consistently separate the sibling rough periwinkles Littorina saxatilis and L. arcana. These data suggest (1) that the Nodilittorina/Littoraria Mb profile in L. striata is not unique within the genus Littorina and therefore does not refute the assignment of L. striata to this genus, and (2) that L. scutulata and L. plena occupy a separate position compared to the other species of the subgenus Littorina. This latter result supports the suggestion that L. scutulata and L. plena may constitute a separate subgeneric taxon. Finally, the IEF Mb profiles of Nodilittorina hawaiiensis and Cenchritis muricatus were nearly identical to the Nodilittorina/Littoraria Mb pattern. Yet, PAGE of Mb in Cenchritis muricatus suggests a tentative Mendelian polymorphism. It is concluded that littorinid Mb may not be a useful marker to distinguish closely related species, but rather provides information on 'higher level' systematics