A taxonomic study on the genus Stichillus (Diptera: Phoridae) from South Korea, with a key to species from East Asia.

The South Korean species of the genus Stichillus Enderlein are reviewed and four species are newly recognized. One of them, S. koreanus sp. nov., is described as new to science and the other three species, viz. S. cylindratus Nakayama & Shima, S. japonicus (Matsumura) and S. spinosus Liu & Chou are new to South Korea. Detailed descriptions with photographs of four Korean Stichillus species, and a revised key to males of ten species from East Asia except Mongolia and North Korea are provided.

A taxonomic study on the South Korean Diplonevra (Diptera: Phoridae).

The South Korean species of the genus Diplonevra are revised and eight species are recognized. Three of these species, D. biflagella, sp. nov., D. incisura, sp. nov., and D. nigritarsis, sp. nov., are new to science and four species, D. abbreviata (von Roser, 1840), D. florescens (Turton, 1801), D. hirsuta Michailovskaya, 2000, and D. peregrina (Wiedemann, 1830), are described for the first time in Korea. Distribution of D. bifasciata (Walker, 1860), the only previously recorded species in Korean checklists, is confirmed based on figures of a female specimen in previous publications. Diplonevra lamella Liu Yang, 2016 is considered a junior synonym of D. hirsuta Michailovskaya, 2000. The Chinese and Russian Far East records of D. pachycera (nec Schmitz) are treated as misidentifications of D. incisura, sp. nov. and D. nigritarsis, sp. nov., respectively. Also, the Chinese record of D. taigaensis (nec Michailovskaya) should be identified as D. biflagella, sp. nov. Detailed descriptions and photographs of three new species and four redescribed species and keys to eight males and seven females of Diplonevra species in South Korea are provided.

Taxonomic study on Sinopoda Jäger, 1999 (Araneae, Sparassidae, Heteropodinae), with three new species from Korea.

The genus Sinopoda Jäger, 1999 is a group of huntsman spiders (Araneae: Sparassidae: Heteropodinae), and currently seven species have been reported in Korea. In this study, three new species are described from Korea, Sinopodabigibba sp. nov., Sinopodabogil sp. nov., and Sinopodapantherina sp. nov.; Sinopodajirisanensis Kim & Chae, 2013 is revalidated with neotype designation, and had been formerly synonymized with Sinopodaforcipata (Karsch, 1881). Additionally, all previous records of Sinopodastellatops Jäger & Ono, 2002 and S.forcipata from Korea are deemed misidentifications of S.jirisanensis and S.bogil sp. nov., respectively.

Five new species of the genus Pholcus Walckenaer (Araneae: Pholcidae) from South Korea.

Although the high level of species diversity within the Pholcus phungiformes-group (Araneae: Pholcidae) in the Korean Peninsula has been recognized recently, taxonomic studies, including new species discovery, have not been conducted in western regions of South Korea. In this study, five additional species belonging to the Pholcus phungiformes-group discovered from Seoul and surrounding areas are described as new, viz., Pholcus seoulensis Lee Lee, sp. nov. Pholcus suraksanensis Lee Lee, sp. nov., Pholcus incheonensis Lee Lee, sp. nov., Pholcus seokmodoensis Lee Lee, sp. nov. and Pholcus chilgapsanensis Lee Lee, sp. nov. Detailed descriptions and geographic distributions are provided with accompanying photographs.

Revision of Simulium rufibasis (Diptera: Simuliidae) in Japan and Korea: Chromosomes, DNA, and Morphology.

The widespread nominal black fly Simulium (Simulium) rufibasis Brunetti was reexamined morphologically, chromosomally, and molecularly to determine the status of populations in Japan and Korea with respect to S. rufibasis from the type locality in India and to all other known species in the S. (S.) tuberosum species-group. Morphological comparisons established that the species previously known as S. rufibasis in Japan and Korea is distinct from all other species. Consequently, it was described and illustrated as a new species, Simulium (S.) yamatoense. Simulium yokotense Shiraki, formerly a synonym of S. rufibasis, was morphologically reevaluated and considered a species unplaced to species-group in the subgenus Simulium. Chromosomal analyses of S. yamatoense sp. nov. demonstrated that it is unique among all cytologically known species of the S. tuberosum group and is the sister species of the Taiwanese species tentatively known as S. (S.) arisanum Shiraki. Populations of S. yamatoense sp. nov. included two cytoforms, based on the sex chromosomes. Cytoform A, including topotypical representatives, was found in Kyushu, Japan, whereas cytoform B was found in Korea and Honshu, Japan. Molecular analysis based on the COI mitochondrial gene generally corroborated morphological and chromosomal data that S. yamatoense sp. nov. is a distinct species and, like the chromosomal data, indicate that it is most closely related to S. arisanum, with interspecific genetic distance of 2.92-4.63%.

Rhipidia crane flies (Diptera: Limoniidae) from Korea.

Korean species of the crane fly genus Rhipidia Meigen, 1818 (Diptera: Limoniidae), are taxonomically revised. Rhipidia (Rhipidia) serena, new species, is described and figured. Rhipidia (R.) longa Zhang, Li, Yang, 2014, R. (R.) maculata Meigen, 1818 and R. (R.) sejuga Zhang, Li, Yang, 2014 are recorded for the first time in Korea. Previously known species, Rhipidia (R.) septentrionis Alexander, 1913 is redescribed and illustrated. Identification key for all Korean Rhipidia species is given. Most antennae, wings, male and female terminalia of all species are illustrated for the first time.

New Dicranoptycha Osten Sacken, 1859 Crane flies (Diptera: Limoniidae) of North and South Korea.

Two new species of Dicranoptycha Osten Sacken, 1859, crane flies (Diptera, Limoniidae) from the Korean peninsula are described, illustrated and compared with already known and related species. An identification key and check-list of all Korean Dicranoptycha is presented.

Macrogenomic evidence for the origin of the black fly Simulium suzukii (Diptera: Simuliidae) on Okinawa Island, Japan.

To determine the geographic origin of the black fly Simulium suzukii on Okinawa Island, Japan, macrogenomic profiles derived from its polytene chromosomes were compared with those of mainland and other insular populations of S. suzukii and of the isomorphic Simulium tani species complex. The Okinawan population is a chromosomally unique cytoform, designated 'D,' which is essentially monomorphic and differs by about 27 fixed rearrangements from the chromosomal standard sequence for the subgenus Simulium and by two fixed differences from its nearest known relative, representing the type of S. suzukii, on the main islands of Japan. Chromosomal band sequences revealed two additional, sympatric cytoforms of S. suzukii, designated 'A' and 'B,' each with species status, in Korea, and a third cytoform, designated 'C,' on Hokkaido, Japan. A new cytoform, 'K,' of S. tani from Malaysia, representing the type of S. tani, is more closely related to cytoforms in Thailand, as are populations from Taiwan previously treated as S. suzukii but more closely aligned with S. tani and newly recognized as cytoform 'L' of the latter nominal species. Rooting of chromosomal band sequences by outgroup comparisons allowed directionality of chromosomal rearrangements to be established, enabling phylogenetic inference of cytoforms. Of 41 macrogenomic rearrangements discovered in the five new cytoforms, four provide evidence for a stepwise origin of the Okinawan population from populations characteristic of the main islands of Japan. The macrogenomic approach applied to black flies on Okinawa Island illustrates its potential utility in defining source areas for other species of flies including those that might pose medical and veterinary risks.

Morphology and ultrastructure of the bacterial receptacle in Steinernema nematodes (Nematoda: Steinernematidae).

Infective juveniles of entomopathogenic nematodes in the genus Steinernema harbor symbiotic bacteria, Xenorhabdus spp., in a discrete structure located in the anterior portion of the intestine known as the 'bacterial receptacle' (formerly known as the bacterial or intestinal vesicle). The receptacle itself is a structured environment in which the bacteria are spatially restricted. Inside this receptacle, bacterial symbionts are protected from the environment and grow to fill the receptacle. Until now, no comparative study across different Steinernema spp. has been undertaken to investigate if morphological variation in this structure exists at the interspecific level. In this study, we examined the bacterial receptacles of 25 Steinernema spp. representatives of the currently accepted five evolutionary clades. Our observations confirmed the bacterial receptacle is a modification of the two most anterior cells of the ventricular portion of the intestine. Size of the bacterial receptacle varied across the examined species. Steinernema monticolum (clade II) had the largest receptacle of all examined species (average: 46×17 µm) and S. rarum (no clade affiliation) was noted as the species with the smallest observed receptacle (average: 8×5 µm). At the morphological level, species can be grouped into two categories based on the presence or absence of vesicle within the receptacle. The receptacles of all examined species harbored an intravesicular structure (IVS) with variable morphology. All examined taxa members of the 'feltiae' (clade III) and 'intermedium' (clade II) clades were characterized by having a vesicle. This structure was also observed in S. diaprepesi (clade V), S. riobrave (clade IV) and S. monticolum (clade I).

Size variation of trichospores of Harpella melusinae in larval black flies.

Trichospores of Harpella melusinae in larval black flies from four streams in northwestern South Carolina were measured. The longest fresh trichospore was 242 microm, 38% longer than the reported maximum length of trichospores for this species. After staining with lactophenol cotton blue, trichospore length was significantly reduced by up to 24.4% in fresh larvae and up to 4.9% in fixed larvae. Mean trichospore length differed significantly between seasons and between sampling sites but did not differ significantly between middle and final instars. Trichospore length correlated significantly with host size. We suggest that taxonomic descriptions of trichomycetes should include measurements of fresh, fixed and stained trichospores.

New insights into the colonization and release processes of Xenorhabdus nematophila and the morphology and ultrastructure of the bacterial receptacle of its nematode host, Steinernema carpocapsae.

We present results from epifluorescence, differential interference contrast, and transmission electron microscopy showing that Xenorhabdus nematophila colonizes a receptacle in the anterior intestine of the infective juvenile (IJ) stage of Steinernema carpocapsae. This region is connected to the esophagus at the esophagointestinal junction. The process by which X. nematophila leaves this bacterial receptacle had not been analyzed previously. In this study we monitored the movement of green fluorescent protein-labeled bacteria during the release process. Our observations revealed that Xenorhabdus colonizes the distal region of the receptacle and that exposure to insect hemolymph stimulated forward movement of the bacteria to the esophagointestinal junction. Continued exposure to hemolymph caused a narrow passage in the distal receptacle to widen, allowing movement of Xenorhabdus down the intestine and out the anus. Efficient release of both the wild type and a nonmotile strain was evident in most of the IJs incubated in hemolymph, whereas only a few IJs incubated in nutrient-rich broth released bacterial cells. Incubation of IJs in hemolymph treated with agents that induce nematode paralysis dramatically inhibited the release process. These results suggest that bacterial motility is not required for movement out of the distal region of the receptacle and that hemolymph-induced esophageal pumping provides a force for the release of X. nematophila out of the receptacle and into the intestinal lumen.

Multiple symbiotes in larval black flies (Diptera: Simuliidae): associations of trichomycete fungi with ichthyosporeans, mermithid nematodes, and microsporidia.

Studies of the interactions between two or more species of symbiotic microorganisms in a single host animal have lagged behind those involving interactions between hymenopteran or dipteran parasitoids. We screened the larvae of four species of black flies (Cnephia ornithophilia, Simulium furculatum, Simulium innoxium, and Simulium vandalicum) to determine if the colonization and prevalence of trichomycete fungi were influenced by ichthyosporeans, mermithid nematodes, microsporidia, or other species of trichomycetes. Differences in the layering of the peritrophic matrix of microsporidian-infected larvae, compared with that of uninfected larvae, were associated with greater levels of colonization by the midgut-inhabiting trichomycete Harpella melusinae. Colonization levels of different species of trichomycetes were significantly correlated with one another in only 2 of 11 cases. Aside from the consistent attachment of the trichomycete Simuliomyces microsporus to the ichthyosporean Paramoebidium chattoni, we found little evidence that prevalence and colonization levels of trichomycetes were influenced by other symbiotes, including other trichomycetes. This trend might reflect the physical separation of trichomycetes, which are gut specific, from other symbiotes. In addition, any combinations of symbiotes that were wholly incompatible would not have been observed in our field-collected material.