New Canadian amber deposit fills gap in fossil record near end-Cretaceous mass extinction

Amber preserves an exceptional record of tiny, soft-bodied organisms and chemical environmental signatures, elucidating the evolution of arthropod lineages and the diversity, ecology, and biogeochemistry of ancient ecosystems. However, globally, fossiliferous amber deposits are rare in the latest Cretaceous and surrounding the Cretaceous-Paleogene (K-Pg) mass extinction.1,2,3,4,5 This faunal gap limits our understanding of arthropod diversity and survival across the extinction boundary.2,6 Contrasting hypotheses propose that arthropods were either relatively unaffected by the K-Pg extinction or experienced a steady decline in diversity before the extinction event followed by rapid diversification in the Cenozoic.2,6 These hypotheses are primarily based on arthropod feeding traces on fossil leaves and time-calibrated molecular phylogenies, not direct observation of the fossil record.2,7 Here, we report a diverse amber assemblage from the Late Cretaceous (67.04 ± 0.16 Ma) of the Big Muddy Badlands, Canada. The new deposit fills a critical 16-million-year gap in the arthropod fossil record spanning the K-Pg mass extinction. Seven arthropod orders and at least 11 insect families have been recovered, making the Big Muddy amber deposit the most diverse arthropod assemblage near the K-Pg extinction. Amber chemistry and stable isotopes suggest the amber was produced by coniferous (Cupressaceae) trees in a subtropical swamp near remnants of the Western Interior Seaway. The unexpected abundance of ants from extant families and the virtual absence of arthropods from common, exclusively Cretaceous families suggests that Big Muddy amber may represent a yet unsampled Late Cretaceous environment and provides evidence of a faunal transition before the end of the Cretaceous.

Diagnosing diagnoses - can we improve our taxonomy?

Taxonomic diagnoses should be clear but minimal statements that precisely distinguish a given specimen from other taxa at the same stage of development (e.g., pupa, adult female, egg). Presently, most diagnoses are of uncertain value. It is a great advantage for readers to be able to simply and confidently confirm their identifications after using a key.

Catalog of the Biting Midges of the World (Diptera: Ceratopogonidae)

A list of all valid 6,206 extant and 296 fossil species of Ceratopogonidae described worldwide is provided, along with all their synonyms. A full citation and the country of origin of the type is given, with some larger countries also providing a more specific state or province. For the first time, worldwide, nomina dubia are identified. Numbers of species of each genus and subgenus are listed. Within subfamilies and tribes, genera are listed alphabetically. Five species have newly recognized authors, four have new names and 28 new combinations are recognized, with these listed in a table. A commentary on the state of the systematics in the family and particularly of Culicoides Latreille is given. The museums of the world are listed with the types of various authors of Ceratopogonidae species indicated. Authors providing regional catalogs, as well as summation of various collections are tabulated. The rate of description since 1758 indicates a steady progression of description, with, for example, 1,231 valid species described since the compilation of the world species by Borkent Wirth (1997), till the end of 2018. The diversity in each Region is compared and the numbers of species shared between adjacent Regions presented.

Taxonomic Revision of Neotropical Downeshelea Wirth and Grogan Predaceous Midges (Diptera: Ceratopogonidae)

The genus Downeshelea was described by Wirth and Grogan based on the diagnostic characters of the Monohelea multilineata species group. The first descriptions of species were based on body coloration, which resulted in confusion and misunderstanding of their identification. The aim of this study was to provide an updated diagnosis and description of Downeshelea, describe 18 new species, and redescribe 10 previously poorly described species. New records of species, a key for identification of all New World species, and a table with important morphometric data to distinguish both males and females of the various species are provided along with distribution maps of the 46 known New World species.

Diptera of Canada

The Canadian Diptera fauna is updated. Numbers of species currently known from Canada, total Barcode Index Numbers (BINs), and estimated numbers of undescribed or unrecorded species are provided for each family. An overview of recent changes in the systematics and Canadian faunistics of major groups is provided as well as some general information on biology and life history. A total of 116 families and 9620 described species of Canadian Diptera are reported, representing more than a 36% increase in species numbers since the last comparable assessment by JF McAlpine et al. (1979). Almost 30,000 BINs have so far been obtained from flies in Canada. Estimates of additional number of species remaining to be documented in the country range from 5200 to 20,400.

Pupae of the Nearctic species of Culicoides Latreille subgenus Monoculicoides Khalaf (Diptera: Ceratopogonidae)

There are 160 valid species of Culicoides Latreille described from the Nearctic Region, but many are unknown as immatures or, although partially described, cannot be readily identified. We provide pupal diagnoses, descriptions, and a key to all seven known species of Culicoides subgenus Monoculicoides Khalaf occurring in the Nearctic biogeographic region. A diagnosis of several characters unique to this subgenus is provided to allow for the recognition of the included species from those of other subgeneric groupings. Microphotography of important morphological characters for both the key and descriptions are provided. This study highlights the usefulness of examining the pupae of Culicoides as a tool for species identification. The pupae of Culicoides grandensis Grogan Phillips, C. occidentalis Wirth Jones, and C. shemanchuki Grogan Lysyk are newly described and those of C. riethi Kieffer, C. stigma (Meigen), and C. variipennis Wirth Jones are redescribed in detail. The seventh species, C. sonorensis, was fully described recently.

Remarkable fly (Diptera) diversity in a patch of Costa Rican cloud forest: Why inventory is a vital science

Study of all flies (Diptera) collected for one year from a four-hectare (150 x 266 meter) patch of cloud forest at 1,600 meters above sea level at Zurquí de Moravia, San José Province, Costa Rica (hereafter referred to as Zurquí), revealed an astounding 4,332 species. This amounts to more than half the number of named species of flies for all of Central America. Specimens were collected with two Malaise traps running continuously and with a wide array of supplementary collecting methods for three days of each month. All morphospecies from all 73 families recorded were fully curated by technicians before submission to an international team of 59 taxonomic experts for identification.        Overall, a Malaise trap on the forest edge captured 1,988 species or 51% of all collected dipteran taxa (other than of Phoridae, subsampled only from this and one other Malaise trap). A Malaise trap in the forest sampled 906 species. Of other sampling methods, the combination of four other Malaise traps and an intercept trap, aerial/hand collecting, 10 emergence traps, and four CDC light traps added the greatest number of species to our inventory. This complement of sampling methods was an effective combination for retrieving substantial numbers of species of Diptera. Comparison of select sampling methods (considering 3,487 species of non-phorid Diptera) provided further details regarding how many species were sampled by various methods.        Comparison of species numbers from each of two permanent Malaise traps from Zurquí with those of single Malaise traps at each of Tapantí and Las Alturas, 40 and 180 km distant from Zurquí respectively, suggested significant species turnover. Comparison of the greater number of species collected in all traps from Zurquí did not markedly change the degree of similarity between the three sites, although the actual number of species shared did increase.        Comparisons of the total number of named and unnamed species of Diptera from four hectares at Zurquí is equivalent to 51% of all flies named from Central America, greater than all the named fly fauna of Colombia, equivalent to 14% of named Neotropical species and equal to about 2.7% of all named Diptera worldwide. Clearly the number of species of Diptera in tropical regions has been severely underestimated and the actual number may surpass the number of species of Coleoptera.        Various published extrapolations from limited data to estimate total numbers of species of larger taxonomic categories (e.g., Hexapoda, Arthropoda, Eukaryota, etc.) are highly questionable, and certainly will remain uncertain until we have more exhaustive surveys of all and diverse taxa (like Diptera) from multiple tropical sites.        Morphological characterization of species in inventories provides identifications placed in the context of taxonomy, phylogeny, form, and ecology. DNA barcoding species is a valuable tool to estimate species numbers but used alone fails to provide a broader context for the species identified.

Comprehensive inventory of true flies (Diptera) at a tropical site

Estimations of tropical insect diversity generally suffer from lack of known groups or faunas against which extrapolations can be made, and have seriously underestimated the diversity of some taxa. Here we report the intensive inventory of a four-hectare tropical cloud forest in Costa Rica for one year, which yielded 4332 species of Diptera, providing the first verifiable basis for diversity of a major group of insects at a single site in the tropics. In total 73 families were present, all of which were studied to the species level, providing potentially complete coverage of all families of the order likely to be present at the site. Even so, extrapolations based on our data indicate that with further sampling, the actual total for the site could be closer to 8000 species. Efforts to completely sample a site, although resource-intensive and time-consuming, are needed to better ground estimations of world biodiversity based on limited sampling.

Biodiversity of Simulium metallicum sensu lato (Diptera: Simuliidae), a complex of Neotropical vectors associated with human onchocerciasis

The polytene chromosomes of 130 larvae of the Neotropical Simulium metallicum complex from Brazil, Costa Rica, and Ecuador revealed five cytoforms, including three ('M', 'N', and 'O') that are new and two ('B' and 'J') that represent range extensions of up to 850km. The discovery of three new cytoforms brings the total number in the complex to 17. Cytoforms 'B', 'J', and 'N' are reproductively isolated from one another, and their species status is corroborated by morphological evidence. None of the three new cytoforms is known from current or historical onchocerciasis foci, although 'M' inhabits the periphery of the former Ecuadorian Santiago onchocerciasis focus a mere 30km to the west. The number of fixed chromosomal differences, as many as 24, separating some members of the S. metallicum complex far exceeds that known between members of any other simuliid species complex. Two distinct groupings can be diagnosed within the S. metallicum complex, based on at least eight fixed chromosomal rearrangements and structural characters in the larval stage. Consequently, a recommendation is made to recognize the S. horacioi complex and the S. metallicum complex sensu stricto. Recognition of two separate complexes provides potential phylogenetic content with predictive power for understanding biological phenomena such as vector potential.

FAMILY CORETHRELLIDAE

Corethrellidae are poorly known in Colombia, with few specimens deposited in collections, and only nine named species of Corethrella Coquillett are reported for the country. An additional six undescribed species have been recently collected, indicating that the number of recorded species in Colombia is underestimated.

The Cretaceous Fossil Burmaculex antiquus Confirmed as the Earliest Known Lineage of Mosquitoes (Diptera: Culicidae)

A second female of mid-Cretaceous Burmaculex antiquus Borkent & Grimaldi, preserved in 99 myo Burmese amber, and the oldest known member of the Culicidae, is described in detail. Although generally opaque and distorted, some character states are added or refined. The discovery of well-developed scales on the legs shows that this feature must now be considered a synapomorphy of both the fossil and all extant members of the family. Previously described synapomorphies and further interpretation here confirm the phylogenetic position of this fossil as the sister group to extant and all known fossil Culicidae. It is placed in the new subfamily Burmaculicinae.

New combinations and changes in the classification of Ceratopogonidae (Diptera, biting midges)

This short article contains some necessary taxonomic changes prior to the publication of a chapter on the Ceratopogonidae by the author for the upcoming Manual of Afrotropical Diptera and spearheaded by Ashley Kirk-Spriggs. Some additional placements of three genera to a recently redefined tribe are also included.

How to inventory tropical flies (Diptera)--One of the megadiverse orders of insects

A new approach to inventory Diptera species in tropical habitats is described. A 150 x 266 m patch of cloud forest at Zurquí de Moravia, Costa Rica (10.047N, 84.008W) at 1585 meters asl was sampled with two Malaise traps for slightly more than one year (Sept. 12, 2012-Oct. 18, 2013). Further concomitant sampling with a variety of trapping methods for three days every month and collecting during a one-week intensive "Diptera Blitz", with 19 collaborators collecting on-site, provided diverse additional samples used in the inventory. Two other Costa Rican sites at Tapantí National Park (9.720N, 83.774W, 1600 m) and Las Alturas (8.951N, 82.834W, 1540 m), 40 and 180 km southeast from Zurquí de Moravia, respectively, were each sampled with a single Malaise trap to allow for beta-diversity assessments. Tapantí National Park was sampled from Oct. 28, 2012-Oct. 13, 2013 and Las Alturas from Oct. 13, 2012-Oct. 13, 2013. A worldwide group of 54 expert systematists are identifying to species level all 72 dipteran families present in the trap samples. Five local technicians sampled and prepared material to the highest curatorial standards, ensuring that collaborator efforts were focused on species identification. This project, currently in its final, third year of operation (to end Sept. 1, 2015), has already recorded 2,348 species and with many more yet expected. Unlike previous All Taxon Biodiversity Inventories, this project has attainable goals and will provide the first complete estimate of species richness for one of the four megadiverse insect orders in a tropical region. Considering that this is the first complete survey of one of the largest orders of insects within any tropical region of the planet, there is clearly great need for a consistent and feasible protocol for sampling the smaller but markedly more diverse smaller insects in such ecosystems. By weight of their species diversity and remarkable divergence of habit, the Diptera are an excellent model to gauge microhabitat diversity within such systems. Our model appears to be the first to provide a protocol that can realistically be expected to provide a portrayal of the true species diversity of a megadiverse order of insects in the tropics.

When DNA barcoding and morphology mesh: Ceratopogonidae diversity in Finnmark, Norway

DNA barcoding in Ceratopogonidae has been restricted to interpreting the medically and veterinary important members of Culicoides Latreille. Here the technique is utilised, together with morphological study, to interpret all members of the family in a select area. Limited sampling from the county of Finnmark in northernmost Norway indicated the presence of 54 species, including 14 likely new to science, 16 new to Norway, and one new to Europe. No species were previously recorded from this county. Only 93 species were known for all of Norway before this survey, indicating how poorly studied the group is. We evaluate and discuss morphological characters commonly used in identification of biting midges and relate species diagnoses to released DNA barcode data from 223 specimens forming 58 barcode clusters in our dataset. DNA barcodes and morphology were congruent for all species, except in three morphological species where highly divergent barcode clusters indicate the possible presence of cryptic species.

The pupae of the biting midges of the world (Diptera: Ceratopogonidae), with a generic key and analysis of the phylogenetic relationships between genera

The pupae of species in each of the 45 genera of Ceratopogonidae known in this stage are diagnosed and described. A standard set of terms is provided, with a glossary, for all pertinent structures of the pupal stage within a context of other Culicomorpha. The variety of terms provided by previous authors are synonymized. Some pupal structures are directly related to developing adult structures and these are discussed. A key to the genera (and to the subgenera of Forcipomyia Meigen) allows for their identification. Pupation and pupal behaviour is summarized. A table of all previous descriptions of each stage of the immatures (egg, larva, pupa) is provided, showing that 13% of all validly named extant Ceratopogonidae are known as pupae. This study examined 45% of these species. All species known as fossil pupae are discussed. A phylogenetic analysis based primarily on pupal characters confirms the relationships between the subfamilies as well as the relationships between the genera in Leptoconopinae, Forcipomyiinae and Dasyheleinae. The question of the monophyly of the Culicoidini remains unresolved. Results confirm the paraphyly of the Ceratopogonini and, for the first time, the Sphaeromiini sensu lato, which is divided into Hebetulini (new tribe), Johannsenomyiini Crampton (new status) and Sphaeromiini sensu novum. Sphaeromiini sensu novum includes Sphaeromias Curtis, Leehelea Debenham, Homohelea Kieffer and Xenohelea Kieffer and forms the sister group of the Palpomyiini. Other genera in Sphaeromiini sensu lato not known as pupae are discussed. The genus Mallochohelea Wirth is shown to be polyphyletic and one group of species is therefore recognized as members of the new genus Anebomyia (type species = Mallochohelea atripes Wirth). A number of species previously placed in Stilobezzia Kieffer are shown to belong to Schizonyxhelea Clastrier. Study of the type species of the monotypic genus Nemoromyia Liu and Yu showed it to be a member of the Palpomyia distincta species group and the generic name is therefore a new junior synonym of Palpomyia. Examination of pupae showed that the following species were misplaced and are now in other genera as follows: Schizonyxhelea brevicostalis (Das Gupta & Wirth), 1968: 28 (Stilobezzia) new combination, Schizonyxhelea bulla (Thomsen), 1935: 289 (Stilobezzia) new combination, Schizonyxhelea caribe (Lane & Forattini), 1958: 208 (Stilobezzia) new combination, Schizonyxhelea diminuta (Lane & Forattini), 1958: 209 (Stilobezzia) new combination, Schizonyxhelea obscura (Lane & Forattini), 1958: 216 (Stilobezzia) new combination, Schizonyxhelea panamensis (Lane & Forattini), 1958: 218 (Stilobezzia) new combination, Schizonyxhelea thomsenae (Wirth), 1953: 83 (Stilobezzia) new combination, Schizonyxhelea scutata (Lane & Forattini), 1961: 92 (Stilobezzia) new combination, Pellucidomyia geari (de Meillon & Wirth), 1981: 547 (Macropeza) new combination, Dibezzia prominens (Johannsen) 1932: 435 (Johannsenomyia) new combination, Nilobezzia theileri (de Meillon & Wirth, 1981:552) (Sphaeromias) new combination, Anebomyia atripes (Wirth, 1962: 281) (Mallochohelea) new combination, Anebomyia fluminea (de Meillon & Wirth), 1981: 550 (Mallochohelea) new combination, Anebomyia siricis (de Meillon), 1961: 50 (Sphaeromias) new combination, Anebomyia texensis (Wirth), 1962: 283 (Mallochohelea) new combination, Anebomyia yunnana (Yu & Zou), in Yu et al. 2005: 1503 (Mallochohelea) new combination, Bezzia goezii (Schrank), 1803: 72 (Tipula) new combination (also a nomen nudum), Palpomyia nemorosa (Liu & Yu), 1991: 26 (Nemoromyia) new combination. Bezzia xanthogaster (Kieffer), 1919: 130 (Probezzia) is a junior homonym of Probezzia xanthogaster (Kieffer), 1917: 329 (Bezzia) and is here given the new name Bezzia gilvigaster Borkent. The fossil genus Paraculicoides Pierce, 1966: 94 and its type species Paraculicoides rouseae Pierce, 1966: 94 are removed from the Ceratopogonidae and likely belong in the Psychodidae.

World catalog of extant and fossil Corethrellidae (Diptera)

A world catalog of extant and fossil frog-biting midges (Diptera: Corethrellidae) provides full type information, known life stages, and distribution of each species. There are 105 extant and seven fossil species of Corethrellidae but unnamed species are known from Costa Rica, Colombia and Madagascar. New information on types and other important specimens are provided.

World catalog of extant and fossil Chaoboridae (Diptera)

A world catalog of extant and fossil Chaoboridae provides full type information, distribution of each species, references to keys, references to latest descriptions of each species, and summaries of bionomic information.  There are 51 extant species in six genera and 41 fossil species (2 unplaced) in 19 genera, two of which are extant. Chaoborus lanei (Belkin, Heinemann & Page) is a new synonym of C. braziliensis (Theobald) and C. annulatus Cook is a new synonym of C. festivus Dyar & Shannon.

First description of polytene chromosomes in biting midges (Diptera: Ceratopogonidae)

Polytene chromosomes are described from secretory cells in larvae of Forcipomyia nigra (Winnertz). They are present in large glandular-trichogen cells at the bases of secretory setae and in midgut cells that were observed by transmission electron microscopy and light microscopy. Polytene chromosomes, isolated from the glandular-trichogen cells using aceto-orcein squash technique, measure 50-200 microm, have braid-like strands of chromatin and no bands, features that are unique within the Culicomorpha.

Two new peculiar species of Neotropical Brachypogon Kieffer (Diptera: Ceratopogonidae)

Brachypogon biradialis from southern Argentina and Chile and Brachypogon tico from Costa Rica, are described and illustrated from female specimens. They are provisionally placed in the genus Brachypogon although not exactly fitting in any of the already recognized subgenera of this genus.

THE SYSTEMATICS AND PHYLOGENY OF THE STENOCHIRONOMUS COMPLEX (XESTOCHIRONOMUS, HARRISIUS, and STENOCHIRONOMUS) (DIPTERA: CHIRONOMIDAE)

The Stenochironomus complex contains all those species which exhibit the highly modified, mining larval form previously recognized as typical of only the genus Stenochironomus Kieffer: larvae with a dorsoventrally compressed head capsule, expanded thoracic segments and a long, flaccid abdomen. The complex includes members of Xestochironomus Sublette & Wirth (New World), Harrisius Freeman (Australian Region), Stenochironomus (cosmopolitan) and two larval forms, one from New Zealand and the other from Africa.This revision provides analysis of 12 species of Xestochironomus (five new), four species of Harrisius, and 54 species of Neotropical and Holarctic Stenochironomus (32 new named species, two new species not named, and four new combinations: S. innocuus (Williston), S. semifumosus (Edwards), S. longilobatus (Tokunaga) and S. gracilivalva (Kieffer)). Of these species, the pupae and fourth instar larvae are described for two species of Xestochironomus, Harrisius pallidus Freeman and 24 of the named species of Stenochironomus. Descriptions, diagnoses, keys, and distribution maps are provided for all species in each available stage. Stenochironomus taeniapennis (Coquillett, 1901), S. zonopterus (Mitchell, 1908), and S. exquisitus (Mitchell, 1908) are newly recognized as junior synonyms of S. hilaris (Walker, 1848).A cladistic analysis of all these species suggests that the Stenochironomus complex is monophyletic. The African larval form is the sister group of all other members; Xestochironomus is the sister group of Harrisius, the New Zealand larval form and Stenochironomus; and Stenochironomus is the sister group of Harrisius plus the New Zealand larval form. These relationships suggest possible southern continental affinities. Stenochironomus is composed of two monophyletic species groups, the subgenus Stenochironomus s. str. with species whose larvae mine wood and the new subgenus Petalopholeus (type-species, S. cinctus Townes) with species whose larvae mine leaves.Cladistic patterns show that Caribbean species are related to other New World species, and that North American species are related to Neotropical or Palaearctic species.Larval food type and ecological differences are analyzed using cladistic relationships. The plesiotypic habitat for species of the Stenochironomus complex is running waters.The phylogenetic relationships of Stenochironomus species and their mite parasites are compared and show little congruence.

Distinctive new species of Atrichopogon Kieffer (Diptera: Ceratopogonidae) from Costa Rica

Twenty-one species of Atrichopogon are described from Costa Rica, based primarily on distinctive males. Of these, females are also described for six species. A key to the males of these species allows for their identification within at least the New World. Three of the species are previously named and described: A. lacajae Macfie, A. didymothecae Macfie, and A. longicornis Ewen. The following are new species: A. bicuspis, A. colossus, A. spinosus, A. carnatus, A. lobatus, A. magnus, A. granditibialis, A. barbatus, A. yolancae, A. gamboai, A. granditergitus, A. tirzae, A. asuturus, A. quartibrunneus, A. beccus, A. redactus, A. setosilateralis, and A. tapantiensis. A lectotype is designated for A. didymothecae.Sobre la base de machos caracter sticos, se describen 21 especies de Atrichopogon de Costa Rica, describi ndose tambi n hembras de 6 de ellas. La clave para machos de estas especies permite, al menos, su identificaci n dentro del Nuevo Mundo. Tres especies fueron previamente nominadas y descritas: A. lacajae Macfie, A. didymothecae Macfie, and A. longicornis Ewen. Las siguientes son especies nuevas: A. bicuspis, A. colossus, A. spinosus, A. carnatus, A. lobatus, A. magnus, A. granditibialis, A. barbatus, A. yolancae, A. gamboai, A. granditergitus, A. tirzae, A. asuturus, A. quartibrunneus, A. beccus, A. redactus, A. setosilateralis, and A. tapantiensis. Se designa el lectotipo para A. didymothecae.

Molecular analysis of the biting midges (Diptera: Ceratopogonidae), based on mitochondrial cytochrome oxidase subunit 2

Sequences from the mitochondrial cytochrome oxidase subunit 2 gene (cox2) were determined for 14 species from the family Ceratopogonidae, representing 12 genera and all five subfamilies, along with six representatives of other nematoceran families. The purpose was to develop a molecular phylogeny of the Ceratopogonidae, and interpret the phylogenetic position of the family within the infraorder Culicomorpha. These taxa have been analysed using cladistic methodology which, in combination with an excellent fossil record, provides a well established morphological phylogeny. Sequence analysis of cox2 revealed a high degree of sequence divergence among the species, reflecting in part the antiquity of the family, but also a significant acceleration of sequence evolution in the ceratopogonids compared to other nematoceran Diptera. Phylogenetic reconstruction by neighbor-joining and maximum parsimony gave strong support for an early separation of an ancient lineage that includes the two genera, Austroconops and Leptoconops, from the remainder of the family. The results support the existence of a clade that includes two subfamilies, Dasyheleinae and Forcipomyiinae, and this clade appears as sister to the remaining subfamily, Ceratopogoninae. The molecular phylogeny also supports monophyly of the Ceratopogonidae, and either a sister or paraphyletic relationship of this family with the Chironomidae.

Lizard feeding by Leptoconops (Brachyconops) californiensis (Diptera: Ceratopogonidae) on desert sand dunes

Adult females of Leptoconops (Brachyconops) californiensis Wirth & Atchley and 1 female of Leptoconops (Holoconops) sp. near knowltoni were collected from 5 species of lizards in desert sand dune habitats in San Bernardino and Riverside counties, California, and northern Sonora, Mexico. Feeding by L. californiensis was observed on the dorsum (usually the heads) of the lizards, with up to 6 L. californiensis on a host at 1 time. The L. sp. near knowltoni appeared to be trying to feed but did not contain blood. Midges fed during calm, warm daylight periods from March through October. Reptile feeding by Ceratopogonidae is reviewed.

Review of the Dasyhelea fasciigera species group (Diptera: Ceratopogonidae) with a revision of the Nearctic species

The Dasyhelea fasciigera species group is characterized by males having a gonostylus divided nearly to its base. Five species are present in the Nearctic region: D. tristyla Wirth, D. bifida Zilahi-Sebess, D. fasciigera Kieffer, D. crassiseta n. sp., and D. pollex n. sp. Each species is described and its distribution discussed; a key for the identification of the males of the Nearctic species is provided. A lectotype is designated for D. dentiforceps Tokunaga, from Japan.

The distribution and habitat preferences of the Chaoboridae (Culicomorpha: Diptera) of the Holarctic Region

Distribution and habitat preferences of species of Chaoboridae in the Holarctic Region are described. Coexistence of larvae of different Chaoborus species in various water bodies reflects differences in geographical distribution, habitat preference, and phyletic relationships. Extant sister species with similar habitat preferences are allopatric whereas those with differences may be sympatric. This suggests that the development of ecological divergence must historically precede coexistence of the immatures of species. Species which coexist often differ markedly morphologically and are not immediately related phylogenetically.Corethrella and Chaoborus (Sayomyia) species that occur in the Holarctic Region and Chaoborus pallidus may have southern, tropical phyletic affinities. Distributions of some North American chaoborids suggest the presence of ecological barriers in northwestern U.S.A. that prevent southern extensions of the ranges of boreal species.

Intra- and inter-familial homologies of maxillary palpal sensilla of larval Simuliidae (Diptera: Culicomorpha)

Light and scanning electron microscopy was used to examine innervation and external structure of maxillary sensilla of larvae of various species of Prosimulium, Twinnia, Gymnopais, Crozetia, Stegopterna, Cnephia, Metacnephia, Gigantodax and Simulium, with emphasis on palpal sensilla. For the palpus, 12 apical sensilla of six distinct morphological types are described, named, and homologies established within the Simuliidae. First instar larvae of Prosimulium, Twinnia, and Gymnopais have a linear array of apical sensilla plus apical spicules, both characters synapomorphic for these three taxa. Prosimuliini genera possess cuticular plates around the palpus apex, synapomorphic for these taxa.Interfamilial homologies for most of the Simuliidae larval palpal sensilla are established for those of larvae of Thaumaleidae, Chironomidae, Tanyderidae, and Blephariceridae. Very few homologies could be established for the Culicidae. Thirteen or 14 palpal sensilla appear to be plesiomorphic for larval nematocerous Diptera, with Simuliidae and Culicidae having reduced numbers.