The structure of the cephalic foregut of Neopachygaster (Diptera, Stratiomyidae, Pachygasterinae)

The cephalic portion of the foregut of Neopachygaster is clearly subdivided into the pharynx and oesophagus. The precerebral pharynx is transformed into a well-developed anterior pharyngeal pump with two unpaired dilators and an intrinsic layer of the muscle fibers. There are two pairs of the posterior pharyngeal dilators, attached to the pharynx just behind the brain. According to these features, the pharynx of Neopachygaster has the most plesiomorphic structure among all the members of Stratiomyidae studied so far.     

Morphology and function of the proboscis in Bombyliidae (Diptera, Brachycera) and implications for proboscis evolution in Brachycera

Based on serial semithin sections and SEM photographs of representatives of European Bombyliinae and Anthracinae, the mouthparts of Bombyliidae are studied and compared with the relevant data from literature on other families of Diptera Brachycera. The three moving units of the proboscis (clypeo-cibarial region, haustellum-maxillary base region, and labella) and their structures and muscles are described. Functions and possible movements are inferred from the structures observed. Articulations both between the parts of the organ and to the head capsule enable the fly to retract its proboscis into a resting position. Proboscis movement from a resting to a feeding position encompasses the following submovements: rotating of the basal clypeo-cibarial region (= fulcrum) against the head capsule, folding of the haustellum-maxillary base region against the fulcrum, evagination and invagination of the labial base, and the labella movements. This is a novelty as compared to the rigid proboscis of Tabanidae and agrees largely with the conditions in the Cyclorrhapha. The evolution of these novelties and their functional significance are discussed. The fulcrum, as well as the haustellum-maxillary base, as the new moving units are deduced from the plesiomorphic state as present in Tabanidae by fusions of sclerites, shifts of musculature and formation of new articulations. Accepted: 5 April 2000     

Flies and concealed nectar sources: morphological innovations in the proboscis of Bombyliidae (Diptera)

Bee-flies (Bombyliidae) have morphological adaptations of the mouthparts to particular floral traits. To investigate this the short, plesiomorphic proboscis of Hemipenthes morio was compared with the long, apomorphic proboscis of Bombylius major . A novel feeding position enables B. major to use flowers that open to the side as additional nectar sources. The new horizontal feeding position is enabled by the prolonged ventral base of the proboscis. Bombylius major exploits deep corolla tubes with an elongate proboscis, and an increased efficiency in both the suction pumps and the sealing mechanisms of the proboscis. The exploitation of narrow corolla tubes is made possible by the shift from a sponging feeding mode, exhibited by H. morio , to the exclusively sucking mode in B. major . Besides quantitative changes in the proportions of the different proboscis components, labellar movements as well as the structures of saliva distribution are changed along with this shift. The labial musculature of B. major does not significantly differ from the plesiomorphic state, since both examined species do not only feed on nectar, but also on pollen.     

Community patterns of nectivorous adult parasitoids (Diptera,Bombyliidae) on their resources

Summary Highly diverse assemblages of nectivorous bee flies (Diptera: bombyliidae) occur at desert sites in California presenting an opportunity to investigate the ecology of this little-known group. This study compared communities of adult bee flies visiting flowers at two sites, one in the Mojave Desert (Darwin Plateau) and one in the Great Basin (Mono Basin), during periods of higher and lower resource abundance. The range of resources used by single species varied inversely with the number of species present, with the greatest number of species and smallest niche breadths occurring at the Darwin Plateau. Adult bee flies did not visit flower resources at random. Rather the two major divisions of the family exhibited contrasting patterns of specialization on plant species. Results of this study support the hypothesis that resources were limiting for adult bee flies in the period of lower food abundance at the Darwin Plateau and not limiting at the Mono Basin during this study. Bee flies at the Mono Basin exhibited lower densities per flower (despite higher densities per unit area), lower frequency of feeding, a lower degree of specialization, and less pronounced phenological changes than bee flies at the Darwin Plateau. The data suggest that episodes of population regulation in the non-parasitic (i.e. adult) stage, due to short supply of the adults' food, contribute to determining the structure of parasitoid communities.     

Phylogenetic relationships of the Australian lomatiines (Diptera: Bombyliidae)

Cladistic analysis is used to isolate the monophyletic group of genera that comprise the Australian Lomatiinae and to investigate the relationships between the Australian genera. Cladograms of genera in the Australian Tomophthalmae and Lomatiinae are presented. Myonema Roberts and Neosardus Roberts are placed in the Cylleniinae, Antonia Loew remains in the Antoniinae and Petrorossia Bezzi is placed in the Anthracinae. The relationship of the Australian lomatiines to the world fauna is discussed, as are the relationships between the Australian genera. Docidomyia White is included in the Lomatiinae and is the sister group of all other genera of the subfamily: Comptosia Macquart sens.lat.; Doddosia Edwards, Oncodosia Edwards and Paramonovomyia Evenhuis. The current diagnosis of the Lomatiinae is changed to reflect the inclusion of Docidomyia. The two subgenera of Comptosia sensu Edwards, Aleucosia Edwards and Comptosia , were not each others' closest relatives in the strict consensus tree. Thus Comptosia as currently recognized is paraphyletic and the two subgenera are treated as genera, Aleucosia stat.nov. and Comptosia stat.nov.     

Revision of the Australian genus Oncodosia Edwards (Diptera: Bombyliidae)

.The endemic Australian genus Oncodosia Edwards is redescribed and diagnosed. Four species are recognized, three redescribed and one, O.triangularis , described as new. Lectotypes are designated for O.patula (Walker) and O.plana (Walker). A cladogram of the species is proposed and a key to species is presented. Wings and genitalia are illustrated. New records extend the known generic distribution eastwards across the continent.     

Histological structure of the mouthparts,clypeo-cibarial system,and cephalic foregut in <Emphasis Type="Italic">Philoliche rondani</Emphasis> (Diptera,Tabanidae, Pangoniinae)

The leading factor responsible for the evolution of Philoliche rondani mouthparts, as well as those of the other long-proboscid Pangoniinae, appears to be adaptation to the intake of nectar from concealed sources (flowers with elongated floral tube). Adaptations to blood-sucking, inherent only in females, have morphogenetic and behavioral aspects. Philoliche rondani males, as compared to males of Tabanus-like species, have better developed clypeus, labrum, and labium. The presence of a long proboscis has led to transformation of the labial musculature and complication of the food canal structure. During the intake of nectar, the distalmost portion of this canal is formed only by the labium. The lateral labial folds form a peculiar closing apparatus. The cibarial and pharyngeal pumps of Philoliche rondani are similar to those of other tabanids investigated.     

New species of the genus Chalcochiton Loew (Diptera, Bombyliidae) from Spain and Morocco

Three new species of the genus Chalcochiton Loew (Ch. maroccanus sp. n. and Ch. merlei sp. n. from Morocco and Ch. hispanicus sp. n. from Spain) are described from specimens in the collection of P. du Merle, a well-known French entomologist.     

The oldest bee fly in the French Paleocene (Diptera: Bombyliidae)

Paleolomatia menatensis gen. and sp. n., oldest Bombyliidae sensu stricto, is described from the Paleocene of Menat (France). The new genus, based on the wing venation, is attributed to the rather ‘derived’ subfamily Lomatiinae, strongly supporting a Late Cretaceous age for the diversification of the pollinator bee flies, in relation with the floristic changes and the angiosperm radiation that occurred at the same time.     

A new type of gastropod proboscis: the foregut of Hastula bacillus (Gastropoda: Terebridae)

Hastula bacillus (Deshayes) is a small terebrid gastropod which inhabits sandy surf beaches in southern Thailand, where it feeds upon spionid polychaetes. It possesses a foregut anatomy unlike that of any other gastropod. An elongate arborescent muscular organ, known as the accessory proboscis structure, is extended through the mouth during foraging. When retracted, it is folded into an 's' shape in the permanent rhynchodeum. The accessory proboscis structure bears numerous tufts of short, stiff cilia which are associated with pairs or triplets of dome-like structures. It is suggested that the structures may be chemosensory and concerned with prey location. Hastula bacillus also possesses a retractable labial tube, a long proboscis and buccal tube, dart-shaped radular teeth, an odontophore, an accessory salivary gland, a pair of salivary glands and a well-developed venom gland with muscular bulb. A comparison with other terebrid species suggests that H. bacillus is the most plesiomorphic taxon yet described from the family.     

Five new records of bee flies (Bombyliidae,Diptera) from Saudi Arabia with zoogeographical remarks

Five bee-fly species (Bombyliidae, Diptera) have been listed in this paper as new to the Kingdom of Saudi Arabia. Four of the recorded species have been identified to the level of species, namely: Bombomyiadiscoidea (Fabricius, 1794), Spogostylumcandidum (Sack, 1909), Exoprosopalinearis Bezzi, 1924, and Exoprosopaminos (Meigen, 1804), while the fifth one only to genus, Desmatoneura sp. The species have been collected from Al-Baha and Asir Provinces in the south-western part of the Kingdom. One of the four identified species, Exoprosopalinearis, has an Afrotropical affinity, and another two, Spogostylumcandidum and Bombomyiadiscoidea, have considerable Afrotropical distributions, and this result agrees to some extent with studies considering these parts of the Arabian Peninsula, including Al-Baha and Asir Provinces, having Afrotropical influences and may be included in the Afrotropical Region rather than in the Palaearctic Region or the Eremic zone.     

Structure of cephalic abnormalities in Drosophila melanogaster (Diptera: Drosophilidae)

Scanning and transmission electron microscopy were utilized in studying the cephalic abnormalities of the tu-h strain of Drosophila melanogaster. Abnormalities, appearing as protuberances (growths) of different shapes and sizes, were observed only on or in close proximity to receptor cites. Compound eyes of some flies, besides having such protuberances, either had modified corneal lenses or were absent altogether. Cuticles of the growths were thinner than that of the normal surrounding layer. The epidermal cells associated with setae on the growths or underlying modified corneal lenses remained undifferntiated. Both setae and growths lacked innervation. The receptor portions (retinular sensory cells and secondary pigment cells) of the abnormal compound eye, where the dioptric portions were replaced by protuberances or remained undifferentiated, were unaffected by the mutation. Nuclei of several cells, including oenocytes and fat bodies, close to or underlying epidermal cells of abnormalities, were large and contained compact nucleoli without nucleonemas. Viruslike particles were observed in several nuclei of growth cells. It was concluded from the present study that the alterations induced by the mutation can be only a localized phenomenon restricted to at least several cephalic epidermal cells and/or their derivatives.     

Parasitism of Neotropical Tiger Beetles (Coleoptera: Carabidae: Cicindelinae) by Anthrax (Diptera: Bombyliidae)

Bee flies (Bombyliidae) were recorded as parasitoids of larval tiger beetles at two rain forest localities (near São Paulo and Manaus) in Brazil. Anthrax gideon was reared from larvae of Oxycheila tristis. Up to 33 parasitoid larvae were found on a single tiger beetle host. Pupation of the bee fly took place in late August and the pupal stage lasted 14 days. The host digs horizontal burrows in contrast to the great majority of cicindelids, as does Pseudoxycheila tarsalis, the other known host of A. gideon. Two pupae of another undetermined Anthrax species were reared from larvae of Pentacomia ventralis in Central Amazonia. Pupation of this Anthrax sp. took place in October, the period of lowest host abundance.     

Optical releasers of the innate proboscis extension in the hoverfly Eristalis tenax L. (Syrphidae,Diptera)

Freshly emerged, inexperienced imagos of the hoverfly Eristalis tenax L. extend their proboscis towards small, yellow colour stimuli, such as anther parts and artificial floral guides. The releasing of this behaviour, which is adapted to pollen feeding, was investigated in behavioural tests using white, UV-reflecting artificial flowers with four small screens illuminated with test stimuli serving as artificial floral guides. The releasing of the innate proboscis extension was tested using monochromatic test lights. Within an intensity range from approx. 5·10¹¹ to approx. 10¹⁴ quanta · cm^-2· s^-1, the flies extended their proboscis only towards green and yellow test lights (approx. 520–600 nm). The inhibition of the innate proboscis extension was tested using mixed light stimuli composed of a yellow monochromatic reference light (560 nm, 10¹³ quanta·cm^-2-1) and of a monochromatic test light. When the reference light was mixed with ultraviolet or blue test lights, the releasing of the innate proboscis extension was strongly inhibited, whereas admixing green/yellow light slightly promoted it; admixing red light had no effect. The results indicate that the releasing of the innate proboscis extension is mediated by the photoreceptor type R8y. Other receptor types which could cause the inhibition of the proboscis reaction are discussed.     

Karyotype structure in species of Propsilocerus genus (Diptera, Chironomidae)

Karyotype structure and polytene chromosome banding patterns were studied in two Orthocladiinae siblings--Propsilocerus akamusi (China) and Propsilocerus jacuticus (Russia). Both species have haploid number of chromosome typical for Orthocladiinae (n = 3). An unusual structure of centromeric regions was observed in all three chromosomes of karyotypes in both species. Photomaps of polytene chromosomes are presented. A comparison of karyotypes of P. akamusi and Propsilocerus jacuticus revealed a high level of homology in their banding sequences, however, the presence of fixed paracentric inversions in chromosomal arms IR, IIR, IIIR of Propsilocerus jacuticus has shown a clear-cut phylogenetic divergence. No chromosomal polymorphism was found in both species.     

Mechanical,sensory and glandular structures in the tarsal unguitractor apparatus of Chironomus riparius (Diptera,Chironomidae)

Summary The legs of chironomid midges from a laboratory colony were examined in the region of the joint between the fifth tarsal segment and the pretarsus, especially the surface of the unguitractor and the manner in which the unguitractor fits into a ventromedian groove in the edge of the tarsus when the joint is flexed. The region was reconstructed from serial sections to clarify the spatial relations of the internal structures to one another and to the external structures. Ultrastructural characteristics of the cells and cuticle suggest a secretory function of the unguitractor. An amphinematic scoloparium is suspended between the point at which the unguitractor attaches to its tendon and the transverse diaphragm within the tarsus. This mechanoreceptor could serve as a proprioceptive sensor of the position of unguitractor and tarsus; it could also be an exteroceptor, sensing vibration in the substrate and/or the air. In the context of functional morphology, the clamping of the unguitractor in the ventral hollow in the tarsus could have the effect of resetting the sensitivity of the sensor. On the other hand, this arrangement could also simply act as an energy-saving means of fixing the claws in the grasping position for long periods.Abbreviations aj adhering junction - bl basal labyrinth - bm basement membrane - cc cuticular cap - cd cellular diaphragm - cth cuticular thickening - dp matrix with dense particles - ec enveloping cells - f filaments - fot funnel-like opening of tendon - ic intracellular canaliculi - lp lateral process of ec - pAc process of A cell - pv pulvillus - r rootlets of cilia - sc scolopale cell - sco scoloparium - sd septate desmosomes - t tendon - tb tubular body - tu tubules - u unguis, or claw - upl unguitractor plate