Senostoma
Encyclopedia
Senostoma is a genus of parasitoid tachinid flies in the family Tachinidae
. Endemic to Australasia, the flies are medium-sized, bristly, and long-legged.
first described the genus in 1847 in the work "Diptères Exotiques, Nouveaux Ou Peu Connus, Supplément I", published in Memoires de la Societe royale des sciences, de l'agriculture et des arts, de Lille. Macquart stated that "Senostoma" signifies "narrow mouth".
At various times the name has been used generically, and misapplied to Prodiaphania and Microrutilia. Senostoma is classified in the subfamily Dexiinae; some older texts use the synonym Proseninae.
The genus comprises four species-groups, punctipenne, rubricarinaturn, longipes, and hirsutilunula.
There are approximately 10,000 species described within Tachinidae, and the geographic range and diversity of the species and difficulties encountered in classification means the count is probably thousands more. The monophyletic features that support Tachinidae classification are subtle, and detailed information on most genera and species is sparse. Senostoma is one such genus that lacks extensive research, with most studies having focussed only on a few of its 29 identified species.
, with two species present in New Caledonia
and none in New Zealand. In Australia, members of the genus are non-existent in Cape York Peninsula
and the Northern Territory
. Some species are particularly narrow in distribution; S. basale inhabits only the Gondwana Rainforests, while S. hirticauda and S. simulcercus are limited to Barrington Tops and Tamborine Mountain, respectively.
Senostoma can be found in a variety of habitats in the Australian region, but most species appear to prefer dry eucalypt forest at elevations above 600 metres. Adults are attracted to flowers and feed on their nectar, contributing to pollination, with Leptospermum
being favoured by some species. As well as resting on Eucalyptus
tree trunks and the surrounding substrate at hill-topping
sites, the flies are observable elsewhere feeding on flowers and resting on rocks and vegetation.
s. The larvae develop inside a host, as intercellular endoparasites, consuming and killing the host in the process. For Senostoma, these hosts are exclusively beetles, most usually Scarabaeidae
in the larval stage. In some cases, the host may survive the attack.
The eggs are laid containing mature first instar
s, the female having incubated the eggs within her reproductive system until ready to hatch, a mode of reproduction known as ovolarviparity, more generally known as ovoviviparity
. Deposition usually occurs on the ground and the eggs may hatch within seconds or a few minutes of being laid, whereupon the larvae hunt for a host beetle by burrowing into the soil. Other tachinids lay eggs directly onto potential hosts or food plants and therefore enjoy a higher success rate of infection; the number of eggs produced by Senostoma females is consequently higher than for some other genera, numbering somewhere between 1000 and 3000.
The labrum of the larval mouthparts is sharp and functions as a cutting device, with which they penetrate the integument
of the selected host, possibly helped by enzymes in their saliva. Once established inside the hosts, the larvae feed on them, passing through second and third instars before pupation occurs. Larval development for tachinids may take between one and three weeks to complete, and the death of the host does not usually occur until the final stage, when the fly is ready to emerge for pupation. As such, Senostoma are considered koinobiont parasitoids, as they co-exist with a living, functional host during development and avoid feeding on vital organs or other critical tissues until it is necessary for their continued growth.
Along with other genera, Senostoma flies possess two morphological features that support their inclusion in the Tachinidiae family. As larvae in the first instar, the labrum is attached to the cephalopharyngeal sclerite
s (the skeleton of the larval anterior digestive system), and as adults, the postscutellum is well-developed.
, with males maintaining downward-facing positions on trunks of Eucalyptus trees, at elevations above 900 metres. This behaviour is likely to be applicable to other species within the genus. Each species studied appeared to prefer certain times of day for hill-topping and selected their positions on tree trunks based on bark smoothness or roughness, degree of illumination by sunlight, and distance from the ground. Males are competitive for these positions and can be observed engaging with each other aggressively, approaching each other for face-offs, spiral flights, and simulated copulation. While males congregating at altitude were in abundance, females were infrequently spotted at hill-topping sites, and when present, did not exhibit any territorial behaviour and preferred locations near the substrate. Female absence may be due to females only visiting the congregation sites when ready to mate. Although the behaviour of males and females at elevation are considered to be for mating purposes, direct evidence of this is lacking and little is known of their courtship and mating rituals.
Tachinidae
Tachinidae is a large and rather variable family of true flies within the insect order Diptera, with more than 8,200 known species and many more to be discovered. There are over 1300 species in North America. Insects in this family are commonly called tachina flies or simply tachinids...
. Endemic to Australasia, the flies are medium-sized, bristly, and long-legged.
Taxonomy
French entomologist Justin Pierre Marie MacquartJustin Pierre Marie Macquart
Justin Pierre Marie Macquart was a French entomologist specialising in the study of Diptera. He worked on world species as well as European and described many new species.-Early years:...
first described the genus in 1847 in the work "Diptères Exotiques, Nouveaux Ou Peu Connus, Supplément I", published in Memoires de la Societe royale des sciences, de l'agriculture et des arts, de Lille. Macquart stated that "Senostoma" signifies "narrow mouth".
At various times the name has been used generically, and misapplied to Prodiaphania and Microrutilia. Senostoma is classified in the subfamily Dexiinae; some older texts use the synonym Proseninae.
The genus comprises four species-groups, punctipenne, rubricarinaturn, longipes, and hirsutilunula.
There are approximately 10,000 species described within Tachinidae, and the geographic range and diversity of the species and difficulties encountered in classification means the count is probably thousands more. The monophyletic features that support Tachinidae classification are subtle, and detailed information on most genera and species is sparse. Senostoma is one such genus that lacks extensive research, with most studies having focussed only on a few of its 29 identified species.
Distribution and habitat
As a member of the Dexiinae subfamily, Senostoma flies are endemic to the Australasian region. More specifically, the flies inhabit the Australian mainland and TasmaniaTasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
, with two species present in New Caledonia
New Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...
and none in New Zealand. In Australia, members of the genus are non-existent in Cape York Peninsula
Cape York Peninsula
Cape York Peninsula is a large remote peninsula located in Far North Queensland at the tip of the state of Queensland, Australia, the largest unspoilt wilderness in northern Australia and one of the last remaining wilderness areas on Earth...
and the Northern Territory
Northern Territory
The Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions...
. Some species are particularly narrow in distribution; S. basale inhabits only the Gondwana Rainforests, while S. hirticauda and S. simulcercus are limited to Barrington Tops and Tamborine Mountain, respectively.
Senostoma can be found in a variety of habitats in the Australian region, but most species appear to prefer dry eucalypt forest at elevations above 600 metres. Adults are attracted to flowers and feed on their nectar, contributing to pollination, with Leptospermum
Leptospermum
Leptospermum is a genus of about 80-86 species of plants in the myrtle family Myrtaceae. Most species are endemic to Australia, with the greatest diversity in the south of the continent; but one species extends to New Zealand, another to Malaysia, and L. recurvum is endemic to Malaysia.They...
being favoured by some species. As well as resting on Eucalyptus
Eucalyptus
Eucalyptus is a diverse genus of flowering trees in the myrtle family, Myrtaceae. Members of the genus dominate the tree flora of Australia...
tree trunks and the surrounding substrate at hill-topping
Hill-topping
Hill-topping is a mate-location behaviour seen in many insects including butterflies, dragonflies, wasps, beetles and flies.Males of many butterfly species may be found flying up to and staying on a hilltop - for days on end if necessary. Females, desirous of mating, fly up the hill...
sites, the flies are observable elsewhere feeding on flowers and resting on rocks and vegetation.
Parasitism
As with all known Tachinidae, Senostoma are parasitoidParasitoid
A parasitoid is an organism that spends a significant portion of its life history attached to or within a single host organism in a relationship that is in essence parasitic; unlike a true parasite, however, it ultimately sterilises or kills, and sometimes consumes, the host...
s. The larvae develop inside a host, as intercellular endoparasites, consuming and killing the host in the process. For Senostoma, these hosts are exclusively beetles, most usually Scarabaeidae
Scarabaeidae
The family Scarabaeidae as currently defined consists of over 30,000 species of beetles worldwide. The species in this large family are often called scarabs or scarab beetles. The classification of this family is fairly unstable, with numerous competing theories, and new proposals appearing quite...
in the larval stage. In some cases, the host may survive the attack.
The eggs are laid containing mature first instar
Instar
An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...
s, the female having incubated the eggs within her reproductive system until ready to hatch, a mode of reproduction known as ovolarviparity, more generally known as ovoviviparity
Ovoviviparity
Ovoviviparity, ovovivipary, or ovivipary, is a mode of reproduction in animals in which embryos develop inside eggs that are retained within the mother's body until they are ready to hatch...
. Deposition usually occurs on the ground and the eggs may hatch within seconds or a few minutes of being laid, whereupon the larvae hunt for a host beetle by burrowing into the soil. Other tachinids lay eggs directly onto potential hosts or food plants and therefore enjoy a higher success rate of infection; the number of eggs produced by Senostoma females is consequently higher than for some other genera, numbering somewhere between 1000 and 3000.
The labrum of the larval mouthparts is sharp and functions as a cutting device, with which they penetrate the integument
Integumentary system
The integumentary system is the organ system that protects the body from damage, comprising the skin and its appendages...
of the selected host, possibly helped by enzymes in their saliva. Once established inside the hosts, the larvae feed on them, passing through second and third instars before pupation occurs. Larval development for tachinids may take between one and three weeks to complete, and the death of the host does not usually occur until the final stage, when the fly is ready to emerge for pupation. As such, Senostoma are considered koinobiont parasitoids, as they co-exist with a living, functional host during development and avoid feeding on vital organs or other critical tissues until it is necessary for their continued growth.
Morphology
Adult members of the genus have bristly bodies and long, thin legs. Their size is generally in the range of 10 to 12 mm, making them medium sized within the family, as measurements for tachinids span from 2 mm to 20 mm. Mouthparts are distinctively elongated and narrow. Limited information suggests that Senostoma colourings are usually at the nondescript end of tachinid fly variation, with at least a few species being light grey and brown.Along with other genera, Senostoma flies possess two morphological features that support their inclusion in the Tachinidiae family. As larvae in the first instar, the labrum is attached to the cephalopharyngeal sclerite
Sclerite
A sclerite is a hardened body part. The term is used in various branches of biology for various structures including hardened portions of sponges, but it is most commonly used for the hardened portions of arthropod exoskeletons....
s (the skeleton of the larval anterior digestive system), and as adults, the postscutellum is well-developed.
Behaviour
A few species, S. longipes, S. pallidihirturn, and S. tessellaturn, have been noted to exhibit behaviour strongly suggestive of hill-toppingHill-topping
Hill-topping is a mate-location behaviour seen in many insects including butterflies, dragonflies, wasps, beetles and flies.Males of many butterfly species may be found flying up to and staying on a hilltop - for days on end if necessary. Females, desirous of mating, fly up the hill...
, with males maintaining downward-facing positions on trunks of Eucalyptus trees, at elevations above 900 metres. This behaviour is likely to be applicable to other species within the genus. Each species studied appeared to prefer certain times of day for hill-topping and selected their positions on tree trunks based on bark smoothness or roughness, degree of illumination by sunlight, and distance from the ground. Males are competitive for these positions and can be observed engaging with each other aggressively, approaching each other for face-offs, spiral flights, and simulated copulation. While males congregating at altitude were in abundance, females were infrequently spotted at hill-topping sites, and when present, did not exhibit any territorial behaviour and preferred locations near the substrate. Female absence may be due to females only visiting the congregation sites when ready to mate. Although the behaviour of males and females at elevation are considered to be for mating purposes, direct evidence of this is lacking and little is known of their courtship and mating rituals.
Species
- S. apicale CurranCharles Howard CurranCharles Howard Curran was an Canadian entomologist who specialised in Diptera....
, 1938 - S. appendiculatum MacquartJustin Pierre Marie MacquartJustin Pierre Marie Macquart was a French entomologist specialising in the study of Diptera. He worked on world species as well as European and described many new species.-Early years:...
, 1851 - S. atripes MallochJohn Russell MallochJohn Russell Malloch was a Scottish entomologist who specialised in Diptera.In 1910 he emigrated to Urbana, Illinois, United States.-References:See...
, 1930 - S. basale CurranCharles Howard CurranCharles Howard Curran was an Canadian entomologist who specialised in Diptera....
, 1938 - S. brevipalpe MacquartJustin Pierre Marie MacquartJustin Pierre Marie Macquart was a French entomologist specialising in the study of Diptera. He worked on world species as well as European and described many new species.-Early years:...
, 1846 - S. commune MallochJohn Russell MallochJohn Russell Malloch was a Scottish entomologist who specialised in Diptera.In 1910 he emigrated to Urbana, Illinois, United States.-References:See...
, 1930 - S. flavipes Barraclough, 1991
- S. flavohirtum MallochJohn Russell MallochJohn Russell Malloch was a Scottish entomologist who specialised in Diptera.In 1910 he emigrated to Urbana, Illinois, United States.-References:See...
, 1930 - S. hirsutilunula Barraclough, 1992
- S. hirticauda MallochJohn Russell MallochJohn Russell Malloch was a Scottish entomologist who specialised in Diptera.In 1910 he emigrated to Urbana, Illinois, United States.-References:See...
, 1930 - S. hyria WalkerFrancis Walker (entomologist)Francis Walker was an English entomologist. He was one of the most prolific authors in entomology, and stirred controversy during his later life as his publications resulted in a huge number of junior synonyms....
, 1849 - S. longimentum Barraclough, 1992
- S. mcalpinei Barraclough, 1992
- S. mixtum MallochJohn Russell MallochJohn Russell Malloch was a Scottish entomologist who specialised in Diptera.In 1910 he emigrated to Urbana, Illinois, United States.-References:See...
, 1930 - S. modestum MallochJohn Russell MallochJohn Russell Malloch was a Scottish entomologist who specialised in Diptera.In 1910 he emigrated to Urbana, Illinois, United States.-References:See...
, 1930 - S. nigrihirtum MallochJohn Russell MallochJohn Russell Malloch was a Scottish entomologist who specialised in Diptera.In 1910 he emigrated to Urbana, Illinois, United States.-References:See...
, 1930 - S. nigropilosum Barraclough, 1992
- S. nigrospiraculum Barraclough, 1992
- S. notatum WalkerFrancis Walker (entomologist)Francis Walker was an English entomologist. He was one of the most prolific authors in entomology, and stirred controversy during his later life as his publications resulted in a huge number of junior synonyms....
, 1853 - S. pallidihirtum MallochJohn Russell MallochJohn Russell Malloch was a Scottish entomologist who specialised in Diptera.In 1910 he emigrated to Urbana, Illinois, United States.-References:See...
, 1930 - S. pectinatum Barraclough, 1992
- S. punctipenne MacquartJustin Pierre Marie MacquartJustin Pierre Marie Macquart was a French entomologist specialising in the study of Diptera. He worked on world species as well as European and described many new species.-Early years:...
, 1846 - S. rubricarinatum MacquartJustin Pierre Marie MacquartJustin Pierre Marie Macquart was a French entomologist specialising in the study of Diptera. He worked on world species as well as European and described many new species.-Early years:...
, 1846 - S. setigerum MallochJohn Russell MallochJohn Russell Malloch was a Scottish entomologist who specialised in Diptera.In 1910 he emigrated to Urbana, Illinois, United States.-References:See...
, 1930 - S. setiventre MallochJohn Russell MallochJohn Russell Malloch was a Scottish entomologist who specialised in Diptera.In 1910 he emigrated to Urbana, Illinois, United States.-References:See...
, 1930 - S. simulcercus Barraclough, 1992
- S. taylori CurranCharles Howard CurranCharles Howard Curran was an Canadian entomologist who specialised in Diptera....
, 1938 - S. tenuipes BigotJacques-Marie-Frangile BigotJacques Marie Frangile Bigot was a French naturalist and entomologist most noted for his studies of Diptera. Born in Paris, where he lived all his life, though he had a small house in Quincy-sous-Sénart, Essonne.He became a member of the Entomological Society of France in 1844. His first paper...
, 1885 - S. tessellatum MacquartJustin Pierre Marie MacquartJustin Pierre Marie Macquart was a French entomologist specialising in the study of Diptera. He worked on world species as well as European and described many new species.-Early years:...
, 1851 - S. testaceicorne MacquartJustin Pierre Marie MacquartJustin Pierre Marie Macquart was a French entomologist specialising in the study of Diptera. He worked on world species as well as European and described many new species.-Early years:...
, 1851 - S. unipunctum MallochJohn Russell MallochJohn Russell Malloch was a Scottish entomologist who specialised in Diptera.In 1910 he emigrated to Urbana, Illinois, United States.-References:See...
, 1930 - S. variegatum MacquartJustin Pierre Marie MacquartJustin Pierre Marie Macquart was a French entomologist specialising in the study of Diptera. He worked on world species as well as European and described many new species.-Early years:...
, 1847