Gnat Species Research Articles

How widespread is pollination by sexual deception of fungus gnats in Pterostylis (Orchidaceae)?

Abstract Pollination by sexual deception has evolved multiple times in the Orchidaceae, with most known cases involving male Hymenoptera as pollinators. The diverse Australasian orchid genus Pterostylis, characterized by elaborate trap flowers, contains some species pollinated by sexual deception of fungus gnats (Diptera). However, there is considerable variation in floral morphology, suggesting that additional pollination strategies or pollen vectors may be involved. Here, we test the hypothesis that sexual deception of male Diptera is taxonomically widespread by investigating the pollination systems across a representative subset spanning nine out of 10 sections and 18 Pterostylis species. We confirm four new cases of pollination by sexual deception of male fungus gnats (families Mycetophilidae, Keroplatidae, and Sciaridae) and accrued evidence for three further cases. Each of these orchids was pollinated by a single species of fungus gnat, with two species exploiting the same pollinator. Unexpectedly, we observed insect feeding behaviour on two species pollinated by sciarid gnats and phorid flies, respectively, with trace levels of sucrose detected where feeding was observed. Our results show that the sexual deception of male fungus gnats is likely to be the dominant mode of pollination in Pterostylis, although other poorly understood pollination strategies are also present.

Notes on the systematic position and distribution of Mycomya supernivea (Diptera, Mycetophilidae) in Japan

Mycomya supernivea Nakamura and Saigusa, 2020 is a recently described large-sized cold-adapted fungus gnat species known from the island of Hokkaido and the northern part of Honshu in Japan. This study reports the species for the first time from Shikoku Island and the central part of Honshu, indicating that the species is more widely distributed throughout the Japanese islands. Additionally, the systematic position of M. supernivae within the genus Mycomya is discussed, and it is placed under the subgenus Mycomya s. str. within the species group M. matrona.

On the identity and distribution of the rare Rymosia tolleti Burghele-Balacesco, 1965 (Diptera, Mycetophilidae) encountered in European caves

The identity and distribution of a neglected fungus gnat species, Rymosia tolleti Burghele-Balacesco, 1965, in Europe is reviewed based on examination of newly collected specimens as well as available museum mate-rials. Rymosia tolleti is widespread but rather rare in Central Europe, with confirmed records from Romania, Slo-vakia, Germany, and France. All the specimens with known collection details originate from cave environments. Detailed photographs of the male terminalia are provided for the first time, along with two unique DNA barcodes for the species.

Every Single Specimen Counts: A New Docosia Winnertz (Diptera: Mycetophilidae) Species Described from a Singleton.

Simple SummaryA new fungus gnat species has been described from a single specimen collected from Georgia (Sakartvelo). The new species, named after its occurrence in Caucasia as Docosia caucasica sp. n., is distinguished from congeners by the characters in male terminalia and a unique COI sequence. As a substantial proportion of species in ecological communities tend to be rare, about 20–30% of new insect taxa have been described from a singleton so far. Therefore, following high-quality standards when describing new species, particularly when dealing with minimalistic material, is crucial. As much as possible, using multiple sets of characters, like morphology and DNA sequencing, is encouraged.A new species—Docosia caucasica sp. n.—has been described from material collected from the Lesser Caucasus Mountains in Georgia (Sakartvelo). The new species belongs to a group of Palaearctic species characterized by distinct posterolateral processes of gonocoxites and apically modified setae at the posteroventral margin of the gonocoxites medially. Within the group, D. caucasica sp. n. is most similar to D. landrocki Laštovka and Ševčík, 2006 in having a similar outline of the medial process of posteroventral margin of the gonocoxites and the gonostylus. There is also a marked difference within the partial cytochrome c oxidase subunit 1 gene (COI) sequence of D. caucasica sp. n. and other Docosia spp. available in public databases. As the new species is described from a single male specimen only, the adequacy and code compliance of that are discussed.

A contribution towards checklist of fungus gnats (Diptera, Diadocidiidae, Ditomyiidae, Bolitophilidae, Keroplatidae, Mycetophilidae) in Georgia, Transcaucasia.

The fungus gnats of Georgia are studied based on 2682 specimens collected from 57 localities during 2011–2019. Altogether, 245 species are recorded including four species of Bolitophilidae, three species of Diadocidiidae, two species of Ditomyiidae, 34 species of Keroplatidae and 202 species of Mycetophilidae. 230 and 188 species are recorded from Georgia and the whole of Transcaucasia for the first time, respectively. Three new species – Sciophila georgei sp. nov., Leia katae sp. nov. and Anatella metae sp. nov. – are described including detailed illustrations of the male terminalia. Photographs are provided for an additional 38 species to highlight a variability of their general facies. Combined with earlier published data, the number of fungus gnat species in Georgia is set at 246. The estimated diversity of fungus gnats in Georgia is calculated using non-parametric methods and discussed with respect to other Western Palaearctic regions.

Sciarid pests (Diptera: Sciaridae) from undercover crop production in South Africa

Fungus gnats (sciarids) are among the most important pests in undercover crop production. They cause direct physical damage to plant roots, transfer fungal pathogens and create entry points for soil-borne plant pathogens. In 2007, Bradysia impatiens, an important fungus gnat pest was found in association with major tree nursery beds in the Mpumalanga and KwaZulu-Natal Provinces of South Africa and was considered invasive. In this study, eight greenhouses were surveyed in the Western Cape Province and B. impatiens was found to be present in all the greenhouses. Similar to the results of the previous studies, a high haplotype diversity was identified for B. impatiens, which may indicate multiple strain introductions into South Africa. Two other fungus gnat species, Lycoriella sativae and Lycoriella ingenua – globally important sciarid pests of mushroom cultures – were identified as new from South Africa. Through a laboratory culture, the life cycle of B. impatiens was observed to be approximately 21 days at 25 °C. Females laid between 100 and 250 eggs. Possible introduction sources include contaminated vegetative material and growth media, thus there maybe need to revise the importation restrictions on these commodities. The identification of two novel species of sciarid pests that have only previously been identified in the Holarctic region could further emphasise this need. However, the recent discovery of such high sciarid diversity could also be due to only a few studies having been previously done on sciarid pests in South Africa.
 Significance:
 
 The fungus gnat species Bradysia impatiens is reported as present in several undercover crops in the Western Cape Province of South Africa, including cucumbers, tomatoes, chrysanthemums, mushrooms, blueberries and various herbs.
 Lycoriella ingenua and Lycoriella sativae were also found to be present in mushroom gardens – the first report of Lycoriella from the Afro-tropical region.
 The three fungus gnat species are some of the most important sciarid pests in undercover crop production worldwide. This study highlights the need for more studies on the distribution of these sciarids and possible invasion history.
 
 Open data set:
 https://www.ncbi.nlm.nih.gov/popset?DbFrom=nuccore&Cmd=Link&LinkName=nuccore_popset&IdsFromResult=1654675097

A New Nearctic Species of Diadocidia Ruthe Fungus Gnat (Diptera: Diadocidiidae)

A new species of Diadocidia Ruthe fungus gnat was discovered in a mixed pine and hardwood forest in the eastern Lower Peninsula of Michigan. Diadocidia longivena Taber is the fourth species recorded from North America and the first new species of the genus described from the Nearctic in 63 years. The fly belongs to subgenus Adidocidia Laŝtovka and Matile, as do both of its congeners that were described in North America.

Development of Lycoriella ingenua and Bradysia impatiens on different phases of agaricus composts

Fungus gnats are small, dark colored, mosquito like fragile insects. They can be encountered all around the world, excluding places with extreme climate. Gnats prefer habitats that are damp with high relative humidity and rich in organic debris. Most of the species are not considered to be harmful in agriculture, but some may cause serious damage, especially in forcing of vegetable or ornamental plants. In mushroom production, however, they are considered as the most destructive pests; the damage caused by them alone can result in huge loss for mushroom farmers. In the Hungarian mushroom industry, fungus gnats damage mainly white-button mushroom, oyster mushroom and pioppino productions. Lycoriella ingenua (Dufour, 1839) and Bradysia impatiens (Johannsen, 1912) are the two most commonly found fungus gnat species from the family Sciaridae on Hungarian mushroom farms.
 We have conducted an experiment with the two aforementioned species, to find out, whether they can fully develop into adults, feeding purely on Agaricus compost diet. We used unspawned white button mushroom compost (phase 2) and spawned compost which has been colonized by the mycelia of Agaricus bisporus (phase 3). We did not conduct any experiment with the first compost phase, as it undergoes pasteurization, which eliminates any pests in it. We recorded emerging gnats only from phase 2 compost. Neither L. ingenua, nor B. impatiens could complete its development on phase 3 compost diet, furthermore not even pupae were observed in these breeding pots. From pots containing phase 2 compost, a total of 1607 adults emerged. The number of B. impatiens adults was 653, and 954 for L. ingenua. Sex ratios for the two species were different. For B. impatiens, the number of females was 1.36 times greater than that of males, in L. ingenua there were 1.7 times more males than females in total. Swarming took approximately 6 days for B. impatiens and 10 days for L. ingenua. From the experiment we can conclude that phase 3 compost, which is well interwoven with Agaricus bisporus mycelia is not suitable for B. impatiens and L. ingenua to complete their whole life cycle.

A new name for a fossil species of Sylvicola (Diptera: Anisopodidae)

The name punctata Wojtoń, Kania & Kopeć, 2018, as used for a new species of fossil species of wood gnat (Anisopodidae) is replaced by harrisi, nom. nov.

Revision of the black fungus gnat species (Diptera: Sciaridae) described by W.A. Steffan from Micronesia.

On the Micronesian Islands 20 species belonging to ten sciarid genera were detected. The revision resulted in the following three new combinations: Cratyna brevipalpis (Steffan) comb. n., Epidapus jaluitensis (Steffan) comb. n., and Epidapus yapensis (Steffan) comb. n. Two species are declared as new synonyms: B. snyderi Steffan, 1969 syn. n. of Bradysia kraussi Steffan, 1969 and Epidapus nanus Menzel, 2007 syn. n. of Epidapus jaluitensis (Steffan, 1969). Bradysia radicum (Brunetti, 1912) was misinterpreted by Steffan and is not yet known to occur in Micronesia. All revised species are figured.

Revision of black fungus gnat species (Diptera, Sciaridae) described from the Hawaiian Islands by D.E. Hardy and W.A. Steffan, and a contribution to the knowledge of the sciarid fauna of the Galápagos Islands.

On the Hawaiian Islands 22 sciarid species were detected, belonging to the following ten genera: Austrosciara Schmitz Mjöberg, Bradysia Winnertz, Corynoptera Winnertz, Cratyna Winnertz, Epidapus Haliday, Hyperlasion Schmitz, Lycoriella Frey, Phytosciara Frey, Pseudolycoriella Menzel Mohrig and Scatopsciara Edwards. The revision resulted in new combinations for the following five species: Austrosciara hawaiiensis (Hardy) comb. n., Corynoptera prominens (Hardy) comb. n., Cratyna adrostylata (Hardy) comb. n., Cr. longicosta (Hardy) comb. n., and Scatopsciara hoyti (Hardy) comb. n. Eight species were declared as new synonyms: Bradysia bishopi Steffan, 1973 = B. centidens Vilkamaa, Hippa Mohrig, 2012 syn. n.; B. crassicornis (Skuse, 1890) = B. molokaiensis (Grimshaw, 1901) syn. n. and = B. aspercera Mohrig, 2016 syn. n.; B. radicum (Brunetti, 1912) = B. spatitergum (Hardy, 1956) syn. n.; Corynoptera prominens (Hardy, 1956) = C. gladiota Mohrig, 2004 syn. n.; Cosmosciara hartii (Johannsen, 1912) = Plastosciara (Plastosciara) latipons Hardy, 1956 syn. n.; Hyperlasion wasmanni (Schmitz, 1918) = Scythropochroa magnisensoria Hardy, 1956 syn. n.; and Scatopsciara hoyti (Hardy, 1956) = Sc. spiculata Vilkamaa, Hippa Mohrig, 2012 syn. n. These four species are new reports for Hawai'i, three of them are new to science: Epidapus pallidus (Séguy), Pseudolycoriella nigrofemoralis Mohrig, Kauschke Broadley sp. n., Scatopsciara hardyi Mohrig, Kauschke Broadley sp. n. and Sc. steffani Mohrig, Kauschke Broadley sp. n. A lectotype was designated for Bradysia radicum (Brunetti) in order to fix the name. All new and revised species are figured. The species Bradysia bishopi Steffan, 1973, B. ocellaris (Comstock, 1882), B. radicum (Brunetti, 1912), Cosmosciara hartii(Johannsen, 1912),Pseudolycoriellaplaniforceps (Steffan, 1971) and Scatopsciara steffani Mohrig, Kauschke Broadley sp. n. are reported from the Galápagos Islands.

A new peculiar species of <i>Anaclileia</i> Meunier (Diptera: Mycetophilidae) from Georgia, Transcaucasia

A new fungus gnat species, Anaclileia adjarica sp. n. (Diptera:Mycetophilidae) from Georgia is described, illustrated and discussed. The species represents the first record of the genus from Georgia as well as from whole Caucasus region. The new species is distinguished by the peculiar and unique structure of the male terminalia, especially that of the tergite 9 which includes posterolateral megasetae and a heart-shaped aggregation of small spines. The possible distributional range of the new species is discussed.

A New Nearctic Species ofDocosiaWinnertz Fungus Gnat (Diptera: Mycetophilidae) from Michigan

A new species of Docosia Winnertz fungus gnat was discovered in the northern Lower Peninsula of Michigan. Two adult males flew in midsummer to a Malaise trap next to a pine swamp. The flies could not be identified by key to genus because wing vein R1 was longer than allowed by the key for Docosia. Adult females and juvenile stages of Docosia mcgrawi Taber are unknown.

Species-specific male pollinators found for three native New Zealand greenhood orchids (Pterostylis spp.) suggest pollination by sexual deception

Many orchids achieve pollination by deceptive means. Sexually deceptive orchids are pollinated by male insects, which are lured to flowers that mimic the sex pheromones and/or appearance of their female conspecifics. This specialised pollination strategy was recently confirmed for the first time in a Pterostylis species in Australia. We investigated whether this pollination strategy may also be operating in Pterostylis species in New Zealand where generalised plant–insect pollination strategies are most commonly documented. The breeding systems of Pterostylis oliveri Petrie and Pterostylis irsoniana Hatch were investigated in the field with pollination treatments. Sticky traps were set up over flowering P. oliveri, P. irsoniana and Pterostylis venosa Colenso to catch potential pollinators of the flowers. Insects caught carrying orchid pollinia were identified, and the pollinia were identified to plant species with nuclear rDNA internal transcribed spacer (nrDNA ITS) sequences. Both P. oliveri and P. irsoniana were found to be self-compatible, but dependent on insects for pollination. Pollinia from each of the three Pterostylis spp. were found to be carried species-specifically by male fungus gnats (Diptera: Mycetophilidae): only Mycetophila latifascia fungus gnats carried the pollinia of P. oliveri, Morganiella fusca gnats carried the pollinia of P. irsoniana, and Tetragoneura sp. carried the pollinia of P. venosa. The pollinator specificity indicates that each of the male fungus gnat species was attracted to the flowers of a specific Pterostylis orchid. This strongly suggests that each of the orchid species emit a specific floral volatile, most probably resembling the sex pheromones of the female conspecifics, to lure their male pollinators. These are the first documented cases of highly specialised sexually deceptive pollination in New Zealand orchids, which were thought to be predominantly self-pollinating.

New and poorly known Palaearctic fungus gnats (Diptera, Sciaroidea).

BackgroundFungus gnats (Sciaroidea) are a globally species rich group of lower Diptera. In Europe, Fennoscandian peninsula in particular holds a notable diversity, ca. 1000 species, of which 10 % are still unnamed. Fungus gnats are predominantly terrestrial insects, but some species dwell in wetland habitats.New informationEight new fungus gnat species, belonging to the families Keroplatidae (Orfelia boreoalpina Salmela sp.n.) and Mycetophilidae (Sciophila holopaineni Salmela sp.n., S. curvata Salmela sp.n., Boletina sasakawai Salmela & Kolcsár sp.n., B. norokorpii Salmela & Kolcsár sp.n., Phronia sompio Salmela sp.n., P. reducta Salmela sp.n., P. prolongata Salmela sp.n.), are described. Four of the species are known from Fennoscandia only whilst two are supposed to have boreo-alpine disjunct ranges, i.e. having populations in Fennoscandia and the Central European Alps. One of the species probably has a boreal range (Finnish Lapland and Central Siberia). Type material of Boletina curta Sasakawa & Kimura from Japan was found to consist of two species, and a further species close to these taxa is described from Finland. Phronia elegantula Hackman is redescribed and reported for the first time from Norway. DNA barcodes are provided for the first time for five species.

Review of three black fungus gnat species (Diptera: Sciaridae) from greenhouses in China: Three greenhouse sciarids from China

Bradysia odoriphaga Yang et Zhang, 1985 syn. nov. is proposed as new synonym of Bradysia cellarum Frey 1948, and Lycoriella pleuroti Yang et Zhang, 1987 syn. nov. as new synonym of Lycoriella ingenua (Dufour, 1839). These results were confirmed by cytochrome oxidase I (COI) DNA barcodes, neighbor-joining (NJ) trees, and a revision of their characters. Illustrations of the morphological characteristics of these two species are provided. Former published records of Bradysia difformis Frey 1948 from China accord with Bradysia impatiens (Johannsen, 1912), as also shown by COI NJ tree in this paper.

Polyphagy on unpredictable resources does not exclude host specialization: insects feeding on mushrooms.

The degree of ecological specialization plays a crucial role in shaping the structure and functioning of communities. However, comparing specialization within and among groups of organisms is complicated by both methodological issues and conceptual and terminological inconsistencies. Environmental predictability has been considered a key determinant of specialization though empirical evidence is still limited. Fungi and their insect consumers provide a poorly studied but promising system to measure host specialization and test the predictability hypothesis. In this study, we systematically sampled mushrooms in North European boreal forest, and reared total samples of fungivores colonizing the fruitbodies. Due to the unpredictable nature of mushrooms as a resource, low levels of host specialization can be predicted for these insects, which have indeed widely been considered polyphagous. Contrary to expectations, the majority of the studied fungus gnats were found not to exploit their host taxa indiscriminately. Not only were some mushroom taxa never colonized, the infestation rate of acceptable hosts also differed in most of these fungivores. Gnat species themselves formed continua with respect to the estimates of the degree of specialization, derived from parametric individual-based analyses of presence-absence data. In most cases, host use was best explained by models in which the hosts were classified at genus level, with limited support to specialization to particular host species, families, or orders. Indeed, most of the common fungivores appeared to preferentially use various species from one or a few mushroom genera while occasionally feeding on members of other host taxa. This pattern has likely evolved as a compromise between selective forces stemming from host unpredictability and taxon-specific chemical profiles of the mushrooms. Our study highlights the multidimensional nature of ecological specialization: a high number of acceptable hosts does not preclude considerable discrimination among members of the available resource pool. Such situations can only be revealed by individual-based analyses capable of capturing differences in partner-to-partner interaction intensities.

Additions to the list of Finnish Bibionomorpha (Diptera, Nematocera).

A total of 12 gnat species are reported for the first time from Finland (3 Cecidomyiidae, 1 Keroplatidae, 8 Mycetophilidae), and the occurrence of Macrocera nigropicea Lundström in Finland is verified. All material was collected from the Finnish Lapland, mainly from the north boreal ecoregion. Two of the recorded species are likely to be pyrophilous, associated with forest fire sites. A photo of the ventral appendage of the gonocoxite of Brevicornu setigerum Zaitzev is provided for the first time. The male hypopygium of Mycetophila haruspica Plassmann is redescribed.

The Mycetophilaruficollis Meigen (Diptera, Mycetophilidae) group in Europe: elucidating species delimitation with COI and ITS2 sequence data.

European species of the Mycetophila ruficollis group are compared on the basis of morphology and sequences of mitochondrial cytochrome oxidase subunit one (COI) and the ITS2 region of nuclear ribosomal DNA. The study represents the first evaluation of morphology-based species delimitation of closely related fungus gnat species by applying molecular information. Detailed descriptions and illustrations of the male terminalia are presented along with a key for the identification of all nine European species of the group. Phylogenetic analyses of molecular data generally supported the morphological species discrimination. The barcoding region of COI superseded ITS2 rDNA in resolving species. In the COI barcoding region interspecific differences ranged from 2.9 to 10.6% and the intraspecific distance from 0.08 to 0.8%. Only COI data distinguished between the similar and closely related Mycetophila ichneumonea and Mycetophila uninotata of which the latter was observed to include cryptic species. The host range of some species is suggested to be narrower than previously considered and to depend on the forest type. Presented evidence indicates the importance of analysing sequence data of morphologically very similar mycetophages reared from identified host fungi for elucidating species delimitation as well as their geographic and host ranges. New country records, viz. Estonia for Mycetophila evanida, Georgia for Mycetophila ichneumonea, Mycetophila idonea and Mycetophila ruficollis, and Norway for Mycetophila strobli, widen the known distribution ranges of these species.

Two new Neuratelia Rondani (Diptera, Mycetophilidae) species from Western Palaearctic: a case of limited congruence between morphology and DNA sequence data.

Two new Mycetophilidae species, Neuratelia jabalmoussae sp. n. and Neuratelia salmelai sp. n. are described on the basis of material collected from Lebanon, Estonia and Finland. Detailed figures of male terminalia and photographs of general facies are provided along with discussions of their morphological distinction from sibling species. For the first time molecular characters are used to distinguish new fungus gnat species. Molecular analysis relies on cytochrome oxidase subunit one (COI) but has additionally been corroborated by information from the 28S and ITS2 regions of nuclear ribosomal DNA. Situations where morphological and molecular data provide conflicting evidence for species delimitation are discussed. A new country record from Georgia is provided for Neuratelia caucasica.