Dong Zhang

Phylogenetic inference of calyptrates, with the first mitogenomes for Gasterophilinae (Diptera: Oestridae) and Paramacronychiinae (Diptera: Sarcophagidae)

The complete mitogenome of the horse stomach bot fly Gasterophilus pecorum (Fabricius) and a near-complete mitogenome of Wohlfahrts wound myiasis fly Wohlfahrtia magnifica (Schiner) were sequenced. The mitogenomes contain the typical 37 mitogenes found in metazoans, organized in the same order and orientation as in other cyclorrhaphan Diptera. Phylogenetic analyses of mitogenomes from 38 calyptrate taxa with and without two non-calyptrate outgroups were performed using Bayesian Inference and Maximum Likelihood. Three sub-analyses were performed on the concatenated data: (1) not partitioned; (2) partitioned by gene; (3) 3rd codon positions of protein-coding genes omitted. We estimated the contribution of each of the mitochondrial genes for phylogenetic analysis, as well as the effect of some popular methodologies on calyptrate phylogeny reconstruction. In the favoured trees, the Oestroidea are nested within the muscoid grade. Relationships at the family level within Oestroidea are (remaining Calliphoridae (Sarcophagidae (Oestridae, Pollenia + Tachinidae))). Our mito-phylogenetic reconstruction of the Calyptratae presents the most extensive taxon coverage so far, and the risk of long-branch attraction is reduced by an appropriate selection of outgroups. We find that in the Calyptratae the ND2, ND5, ND1, COIII, and COI genes are more phylogenetically informative compared with other mitochondrial protein-coding genes. Our study provides evidence that data partitioning and the inclusion of conserved tRNA genes have little influence on calyptrate phylogeny reconstruction, and that the 3rd codon positions of protein-coding genes are not saturated and therefore should be included.

Sensory organs of the antenna of two Fannia species (Diptera: Fanniidae)

The latrine fly (Fannia scalaris) and lesser house fly (Fannia canicularis) are ubiquitous fanniid species of forensic and medical importance. The external morphology of sensilla on the antennae is studied using a stereoscopic microscope and scanning electron microscope, and the internal structure of the antennae is revealed by paraffin sections under the light microscope and laser scanning confocal microscope. Only grooved bristles are found on the scape and pedicel. Four major types of surface sensilla are found on the antennal funiculus and are classified as: (a) trichoid sensilla, (b) two subtypes of basiconic sensilla, (c) clavate sensilla, and (d) coeloconic sensilla. Density of each sensilla type of the two species is calculated. A remarkable difference is observed that the higher density of clavate sensilla occurs on the posteroventral surface in F. scalaris, whereas they are on the anterodorsal surface in F. canicularis. Several cuticular depressions that were previously known as “olfactory pits” are observed on the funiculus of both species. Combining with previous studies, they are suggested to be classified into two types: pit and sacculus. Pit is single-chambered and filled with one type of sensilla, whereas the sacculus is a multi-chambered pit organ containing several types of sensilla. Surprisingly, the pits observed in our study are mostly situated at the lateral region of the antennal funiculus, whereas in other flies, they are found on the posteroventral or anterodorsal surface of antennal funiculus. In addition, the sacculus found in our study houses only basiconic-like sensilla, which is remarkably different from other findings. Moreover, observation under light microscope indicates that previous data of the complexity and the number of the “olfactory pits,” which are an important type of efficient sensory convergence, could be underestimated. Thus, more precise methods such as paraffin section or transmission electron microscope are suggested for further study.

Cuticular structures on antennae of the bot fly, Portschinskia magnifica (Diptera: Oestridae).

Portschinskia magnifica Pleske, 1926, is an endangered subcutaneous parasitic fly of voles that mimics bumblebees in appearance. Although the importance of antennae in Diptera has been repeatedly stressed, there is still a lack of morphology information of this group, let alone this species. Antennae of adult P. magnifica were studied with a stereoscopic microscope and scanning electron microscope. Six subtypes of antennal sensilla were observed on the funiculus and arista (one subtype of trichoid sensilla, one subtype of basiconic sensilla, and four subtypes of coeloconic sensilla). Sensilla on the antennal funiculus from one sample of both male and female flies were also mapped. Female P. magnifica bear a larger number of sensilla than males, and more sensilla were discovered on the posterior surface than on the anterior surface. However, what make this species special are the distinct structures and new morphological characteristics discovered in the antenna. The antennal funiculus of P. magnifica is completely enveloped by an antennal pedicel. A large number of branched or unbranched trichoid and basiconic sensilla are identified on the antennal funiculus. These two make the most numerous types of sensilla distributed all over the funicular surface. P. magnifica has the most coeloconic sensilla subtypes in previously studied oestrid flies. A total of four subtypes of coeloconic sensilla are found, with subtype I and subtype II on the proximal and middle part of the antennal funiculus and subtype III and subtype IV on the antennal arista. Two large bristles that resemble mechanoreceptors on the proximal two antennal segments located close to the arista are a unique feature. This has never been described in the oestrid funiculus. Interestingly, these bristles can appear as multi-tipped short structures in some individuals. P. magnifica lacks sensory pits that are usually abundant in other oestrid flies. The size, number, and distribution of sensilla on the male and female antennal funiculus are provided here, armed with a discussion of their presumable sensilla functions and evolutionary trends.

Ultrastructure of antennal sensilla of a parasitoid fly, Pales pavida Meigen (Diptera: Tachinidae)

Pales pavida Meigen is obligated polyparasitic fly and important natural enemy of some most damaging forest or agricultural pests, and thus could contribute to the biological control of them. The external morphology of main olfactory organs in this tachinid was examined using stereopic microscopy and scanning electron microscopy, and types, distribution and density of sensilla were provided. The first two antennal segments, antennal scape and pedicel, are covered by microtrichiae and several mechanoreceptors. A pedicellar button is detected on antennal pedicel as well, after its separation with antennal funiculus. On antennal funiculus, five types of sensillar structures are observed including trichoid, basiconic, coeloconic, clavate sensilla and sensory pit with subtype II basiconic sensilla and a type of rarely described coeloconic-like sensilla in it, respectively. There are two specific sensillar characteristics of Pales pavida, two types of sensory pit on antennal funiculus and lower densities of all sensilla types than relatively monoparasitic species, which may serve as applicable evidence on their adaption to environment and lifestyle. Besides, the morphology of pedicellar button in tachinids is first addressed, armed with a discussion of their possible function.

Ultrastructure of antennal sensilla in Hydrotaea armipes (Fallén) (Diptera: Muscidae): New evidence for taxonomy of the genus Hydrotaea

The morphology and ultrastructure of the antennal sensilla of male Hydrotaea (Hydrotaea) armipes (Fallén) are examined via scanning electron microscopy in order to highlight the importance of antennal sensilla as a source of morphological characters for taxonomy and phylogeny of Hydrotaea. Antennal scape and pedicel have only one type of sensilla, the sharp-tipped chaetic sensilla, whereas antennal funiculus possesses several types of sensilla, including trichoid sensilla, two subtypes of basiconic sensilla, coeloconic sensilla and clavate sensilla. These results are compared with previously published studies on other fly species, especially on H. (H.) irritans (Fallén) and H. (Ophyra) chalcogaster (Wiedemann), and there are possible uniquely derived characters or diagnostic characters examined on antennal pedicel and antennal funiculus, which suggests either affinities and divergence between species at subgenus level. Thus, new morphological evidence is provided, which might help to develop the much disputed taxonomy of genus Hydrotaea Robineau-Desvoidy in future.

Population genetic structure of Gasterophilus pecorum in the Kalamaili Nature Reserve, Xinjiang, based on mitochondrial cytochrome oxidase (COI) gene sequence

Gasterophilosis is a significant threat to equids in the desert steppe of Xinjiang, China, where Gasterophilus pecorum (Fabricius) (Diptera: Gasterophilidae) is the dominant botfly species. A population analysis was conducted on 195 individual G. pecorum larvae from three host species, Przewalskis horse, the domestic horse and the Asiatic wild ass. The distribution of haplotypes of the maternally inherited mitochondrial cytochrome oxidase subunit I (COI) gene was analysed to assess the population differentiation of G. pecorum. High haplotype diversity was observed among G. pecorum populations from all host species, indicating that the G. pecorum infecting one host had multiple maternal ancestors. A phylogenetic tree showed six clades, suggesting a high degree of genetic differentiation. A constructed haplotype network described both the origin of the haplotypes and the population structure. The findings indicated that G. pecorum infections within Przewalskis horses were mainly transmitted from Asiatic wild asses. Clade 1 was found to be the most primitive group and to have evolved to be highly adaptable to the desert steppe. Clade 2 originated from Clade 1, potentially as a result of the annual migration of domestic horses. Revealing the differentiation of the G. pecorum population is important for elucidating the aetiology of Gasterophilus infection in Xinjiang and for planning appropriate control measures.

Antennal sensory organs of Scathophaga stercoraria (Linnaeus, 1758) (Diptera: Scathophagidae): ultramorphology and phylogenetic implications

Scathophaga stercoraria (Linnaeus, 1758) is a well-established insect model species involved in numerous investigations on behavior, biology, phylogeny, genetics and evolution. The antennal sensilla of S. stercoraria are examined via scanning electron microscopy in order to emphasize their importance on taxonomy and phylogeny. On antennal scape and pedicel, both microtrichiae and several sharp-tipped mechanoreceptors are observed, while another two structures, setiferous plaques and pedicellar button, are also detected on antennal pedicel. One type of sensory pit and four types of antennal sensilla, including trichoid sensilla, basiconic sensilla, coeloconic sensilla and clavate sensilla, are observed on antennal funiculus. Similarity and disparity of setiferous plaques among different calyptrate groups are analyzed in terms of phylogeny. The phylogenetic results supported by morphology of setiferous plaques strongly accord with the cladistic relations based on known molecular tree, implying the potential taxonomic and phylogenetic implications of the plaques in Calyptratae.

Molecules and morphology unite Sarcophaga (Stackelbergeola) Rohdendorf and S. (Rohdendorfisca) Grunin within megadiverse Sarcophaga Meigen (sensu lato) (Diptera, Sarcophagidae)

Abstract. The largest genus of the family Sarcophagidae (Insecta, Diptera), Sarcophaga Meigen (sensu lato), has ∼160 subgenera; however, the validity and phylogenetic relationships of these are still unclear, impeding progress in evolutionary studies. This study presents a phylogenetic hypothesis for selected subgenera of Sarcophaga s.l. based on COI sequences (685 bp) for 87 species representing 27 valid subgenera. The subgenera Stackelbergeola Rohdendorf and Rohdendorfisca Grunin are reconsidered in the light of new molecular, morphological and biological data. The female is described for the first time for a representative of both subgenera, and Sarcophaga (Rohdendorfisca) flagellifera (Grunin) is shown to be a parasitoid of tettigoniid grasshoppers. As the male of Sarcophaga (Stackelbergeola) sushkini (Rohdendorf) is insufficiently documented in the literature, a redescription is provided based on material from Xinjiang, thereby providing the first record of this subgenus and species from China. Detailed documentation through photographs, scanning electron microscopy and illustrations of the adult morphology is also provided. The subgenera Stackelbergeola and Rohdendorfisca are shown to be monophyletic, together forming a monophylum supported by molecular and morphological data, and they are placed in a wider phylogenetic context of the megadiverse genus Sarcophaga s.l.

Review of the genus Agria (Diptera, Sarcophagidae) from China

Abstract Agria mihalyii (Rohdendorf and Verves, 1978) is recorded from China for the first time, and both sexes are thoroughly documented using a combination of illustrations, photographs and scanning electron microscopy images. The generic affiliation is corroborated from an expanded definition of genus Agria Robineau-Desvoidy, 1830, and a key to males of the two known species from China is provided. The distribution of coeloconic sensilla on the male pre- and postgonite are shown to possess significant diagnostic and phylogenetic information in this genus.

Comparative ultrastructure of pretarsi in five calyptrate species

Pretarsi are the most important structures that allow flies to walk on various smooth surfaces and act as contact sensory organs. The pretarsal ultrastructure, including adhesive pads, claws, unguitractors, and bristles, of five calyptrate species are presented and described in detail, including Calliphora calliphoroides (Rohdendorf, 1931), Lucilia sericata (Meigen, 1826), Sarcophaga portschinskyi (Rohdendorf, 1937), Muscina stabulans (Fallen, 1817) and Portschinskia magnifica Pleske, 1926. Two types of tenent setae (spoon-tipped and spatula-tipped) are present on the ventral side of pulvilli in all species. The density of tenent setae and the pulvilli area in forelegs, midlegs, and hindlegs of both sexes are different. Among the five species, Ca. calliphoroides has unusually large pulvilli to its body size. These results provide morphological details that help to understand the movement and attachment of flies.