Type Host Research Articles

A new feather mite species of the genus Temnalges (Acariformes: Psoroptoididae) from coots, Fulica spp. (Gruiformes: Rallidae)

A new feather mite species, Temnalges fulicae sp. n. (Psoroptoididae: Pandalurinae), is described from two species of coots, Fulica americana Gmelin, 1789 (type host), in Canada, and F. atra Linnaeus, 1758, in Denmark. The new species is close to other species of the genus associated with rails (Rallidae), especially to T. megalonyx Gaud, 1968, in having a long spur-like process on tibia III in males, and the prodorsal and hysteronotal shields separated by a wide area of striated tegument in females. Males of Temnalges fulicae are most clearly distinguished from T. megalonyx in having the opisthosoma rounded and without terminal and lateral clefts, and the adanal shields narrow and short. In females, the prodorsal shield has a convex posterior margin, the hysteronotal shield is roughly rectangular, and setae 4a extend to the bases of setae ps3. Additionally, we provide a world checklist and a key to Temnalges species.

A bibliometric and visualization analysis of entosis research from 2007 to 2024.

In 2007, entosis was proposed as a form of programmed cell death, distinct from apoptosis. This process involves a living cell (internalized cell) actively invading a neighboring live cell of the same type (host cell), forming a cell-in-cell structure. Recently, entosis has been increasingly associated with cancer, leading to significant advancements in research. Despite this progress, a comprehensive and unbiased review of the current state of entosis research is lacking. This study aims to evaluate the developments in the field of entosis over the past decade and highlight emerging research trends. We performed a literature search for studies published since the introduction of the entosis concept, using the Web of Science Core Collection database. The bibliometric analysis was conducted using VOSviewer, CiteSpace, Microsoft Excel, and the Bibliometrix R package. A total of 196 articles from 39 countries and 346 institutions were included. Between 2007 and 2024, research on entosis has seen rapid growth, with most publications originating from China and the United States. The United States also leads in total citations, with Memorial Sloan Kettering Cancer Center emerging as the top research institution. Sun Qiang is the most prolific author in this field, while Overholtzer M has the highest number of citations. Current Molecular Medicine has published the most articles related to entosis. Frequently occurring keywords include "entosis," "cannibalism," "autophagy," and "apoptosis." In recent years, keywords such as "phagocytosis," "drug resistance," and "human cancers" have surged, indicating a growing focus on understanding the role of entosis in tumor progression and exploring its potential as a therapeutic target for cancer treatment. This study provides the first bibliometric analysis of entosis, detailing its evolution over the last decade. It highlights critical areas of interest, including the development of inhibitors targeting entosis and their potential clinical applications. This research aims to guide future investigations and serve as a valuable resource for scholars exploring entosis in cancer biology.

Description of three new species of Kudoa Meglitsch, 1947 (Myxozoa: Multivalvulida) in commercial marine fishes from southern China, and new host records.

Multivalvulidan myxosporeans (Multivalvulida) of the genera Unicapsula Davis, 1924 and Kudoa Meglitsch, 1947 are mostly causative agents of latent and imperceptible infection in marine fishes. However, they are sometimes incriminated in causing post-mortem myoliquefaction or unsightly cyst formation in commercial fish. Despite the great commercial impacts of multivalvulidan infection, the biodiversity, host range and epidemiology of multivalvulidan species remain to be explored further, including infection of alternative annelid hosts. Therefore, this study aimed to identify multivalvulidan species and their host and/or distribution records in commercial fishes in China. Multivalvulidan infection was detected in ten commercial fish species of seven families from the South and East China Seas (Northwest Pacific Ocean) and the Eastern Central Atlantic Ocean (an imported Dagetichthys lusitanicus [de Brito Capello]). Based on morphological and molecular-genetic analyses of their small and large subunit of ribosomal RNA genes, five new host and/or geographical distribution records for five fish species are presented, and three new species in five fish species are described, namely Kudoa neoscomberomori sp. n. in Scomberomorus commerson (Lacépède); Kudoa pilosa sp. n. in Helicolenus hilgendorfi (Döderlein) (type host) and Sebastiscus tertius (Barsukov et Chen); and Kudoa tumidisporica sp. n. in Photopectoralis bindus (Valenciennes) (type host) and Nuchequula nuchalis (Temminck et Schlegel). This study provides new data on multivalvulidan diversity in the ocean ecosystem.

Wide variation in aggressiveness and growth in South African Fusarium circinatum isolates with geographical origin as the primary determinant

Fusarium circinatum is a globally important fungal pathogen that causes pitch canker on a wide range of Pinus species. In this study, we considered mycelial growth in culture and aggressiveness of a South African population of F. circinatum isolates. The specific aim was to determine how these phenotypes are correlated with one another and other isolate characteristics, including mating type, host species and geographic origin of the isolates. The study involved the selection of 102 isolates of F. circinatum from five provinces of South Africa based on genotype, mating type and original host from which they were isolated, after which pathogenicity tests were carried out on Pinus patula seedlings. Mycelial growth in culture was also determined for all the isolates at three different temperatures. In the pathogenicity tests, most of the isolates produced significant lesions. While seven had low levels of aggressiveness, other isolates tested were as or more aggressive than a standard set of isolates routinely used for resistance/ tolerance screening. Most F. circinatum isolates grew best at 25 °C, followed by growth at 20 °C and 30 °C. A notable correlation between aggressiveness and the geographical origin was identified. Moreover, the study highlighted a moderately positive relationship between the growth rate of F. circinatum isolates and their reported aggressiveness. The extensive data gathered on the aggressiveness of F. circinatum will offer a broad range of isolates for future comparative studies using other genotypes of F. circinatum and will also aid in the consideration of F. circinatum isolates used for tolerance screening studies.

Insoluble Acyclic Cucurbit[n]uril-Type Receptors Capture Iodine from the Vapor Phase.

Nuclear energy makes large contributions toward meeting global energy needs, but societal concerns remain high given the impacts of the intended release of radioactive materials including 129I and 131I. In this paper we explore the use of a homologous series of acyclic CB[n] type hosts (H1 - H4) as adsorbents of iodine from the vapor phase. We find that H2 - H4, but not H1 - perform well in this application with uptake capacities of 2.2 g g-1, 1.5g g-1, and 1.9g g-1, respectively. The chemisorptive uptake process involves partial oxidation of catechol walled H2 to quinone walled host and capture of I3- and I5-. Solid H2 can be regenerated by treatment with Na2S2O4 and reused at least five times. The x-ray crystal structure of H2 is also reported.

Synonymy, redescription, molecular characterisation, and new distribution data of species of Stilestrongylus and Guerrerostrongylus (Nematoda, Heligmonellidae) parasitic in sigmodontine rodents from Argentina and Uruguay: a collection-based survey

In this study, we review the taxonomic status of the parasitic nematodes Stilestrongylus oryzomysi and Guerrerostrongylus uruguayensis (Heligmonellidae), which had been described only once from sigmodontine rodents from Argentina and Uruguay, respectively. To this aim, we examined 38 complete helminth sets deposited in the Helminthological Collection of the Museo de La Plata (MLP-He), Argentina, including type material of G. uruguayensis, S. oryzomysi, and a closely related species, Stilestrongylus azarai. We also examined voucher rodent specimens deposited in the Mammal Collection of the Museo de La Plata (MLP-Mz) to assess the identity of the symbiotypes and other rodent hosts. Based on these observations, S. oryzomysi is proposed as a junior synonym of S. azarai; the identity of the symbiotype of S. oryzomysi and Trichofreitasia lenti (Heligmonellidae) is emended from Oligoryzomys flavescens to Akodon azarae; G. uruguayensis is proposed as a junior synonym of Guerrerostrongylus zeta; S. azarai is redescribed based on type and voucher material; and the latter species and G. zeta are molecularly characterised using the ITS+ gene. We extend the geographic distribution of S. azarai to include Uruguay and provide a new host record for T. lenti (A. azarae, type host species), a new host record for G. zeta in Argentina (O. flavescens), and the first record of helminths for Oligoryzomys nigripes in Uruguay.

A New Cyst Nematode, Heterodera luodingensis n. sp. (Nematoda: Heteroderinae) From Rice In China.

A unique cyst nematode population (Heterodera spp.) was collected from rice roots in Luoding County, Guangdong Province, China. Morphological and molecular analyses revealed it is significantly different from all previously described cyst nematode species. It is described as Heterodera luodingensis n. sp. and classified in the Cyperi group. H. luodingensis n. sp. is characterized by its lemon-shaped cyst with a prominent terminal vulval cone that is ambifenestrate with abundant bullae and a relatively short vulval slit, 31.3 (24.4 -38.7) μm long. The second-stage juveniles (J2) are characterized by dumbbell shaped labials, three lip annules and a lateral field with three incisures. The J2 stylet is 18.7 (16.9 -19.8) μm long with anterior concave or spherical knobs. The tail is elongate conoid, tapering to a rounded terminus or zig tapering to a rounded terminus that is 54.9 (43.9 - 64.3) μm long with a hyaline region comprising 40.3%-52.5% of the tail. Phylogenetic tree analysis based on rDNA 28S D2D3 and ITS fragments showed that the H. luodingensis n. sp. is unique and clearly separated it from other cyst nematodes. It is most closely related to H. oryzicola, H. fengi, H. elachista, H. oryzae, and H. guangdongensis. H. luodingensis n. sp. can be distinguished from H. oryzicola by its shorter vulval slit and underbridge, from H. elachista by abundant bullae, shorter vulval slit and fenestrate width, from H. oryzae by a shorter vulval slit and underbridge, from H. fengi by a shorter vulval slit, from H. guangdongensis by a longer cyst length and abundant bulla. Based on PCR-RFLP of rDNA-ITS, H. luodingensis n. sp. can be clearly distinguished from H. oryzicola, H. mothi, H. elachista, H. guangdongensis and H. cyperi. A parasitism test from a pure culture derived from a single cyst in greenhouse showed that H. luodingensis n. sp. can successfully complete its life cycle on rice and rice is its type host.

Peronospora species on Myosotis – a showcase for the uncharted diversity of a highly diverse and specialised downy mildew genus

Peronospora is the largest genus of obligate biotrophic oomycetes, causing downy mildew disease on various cultivated and ornamental plants worldwide. Despite the known high host specificity in Peronospora, many host–pathogen combinations have not been thoroughly investigated with respect to their phylogenetic relationships. This is especially the case for groups in which only one species has been described on a host genus. In this study, we highlight the fact that Peronospora is still vastly underexplored by investigating 48 specimens of Peronospora parasitic on the ornamental plant genus Myosotis (Boraginaceae). Morphology and multigene phylogenetic relationships revealed six new Peronospora species parasitic on Myosotis, with one species parasitising the widely cultivated species Myosotis sylvatica, providing further evidence that Peronospora species are generally highly host-specific. As a consequence, Peronospora occurrences on the several hundred plant species that are not type host species for a described Peronospora species should be re-examined, as they might represent species overlooked in previous studies.

P‐200: N‐type Host Derived from Phenyl‐Triazine Moiety for Low Driving Voltage in Blue Phosphorescent Organic Light‐Emitting Diodes

For commercialization of blue phosphorescent OLED, it is desirable to satisfy low driving voltage, high efficiency, and long device lifetime at the same time. In this work, we developed a new phenyl‐triazine type based PTHN‐2 host with oxasiline functional group by applying a novel molecular design strategy that modulates intermolecular distance and electron mobility. The PTNH‐2 host was compared with PTNH‐1 host with tetraphenylsilane functional group instead of oxasiline functional group. The fabricated blue phosphorescent OLEDs with PTNH‐2 as the N type host showed the driving voltage of 4.1 V and the external quantum efficiency of 22.0% relative to driving voltage of 4.5 V and external quantum efficiency of 18.3% collected from PTNH‐1 based blue phosphorescent OLED. Additionally, the device lifetime of the blue phosphorescent OLEDs was extended by more than 100% by replacing PTNH‐1 host with PTNH‐2 host. The driving voltage, quantum efficiency, device lifetime, and power efficiency of the blue phosphorescent OLEDs were dramatically improved by employing the PTNH‐2 host.

Further studies on the diversity of Cylicospirura Vevers, 1922 (Nematoda: Spirocercidae) in African carnivores, with description of a new species.

Cylicospirura Vevers, 1922 is a genus of gastrointestinal spirurid nematodes parasitizing mainly felid but also canid, hyaenid and dasyurid hosts. Presently, 11 species are recognized worldwide, of which 4, Cylicospirura subaequalis, Cylicospirura felinea, Cylicospirura crocutae and Cylicospirura pardalis, have been recorded from African carnivores. In the present study, we describe Cylicospirura phiri n. sp. from hyaenas, namely Crocuta crocuta (type host) in Zimbabwe and Hyaena hyaena in Cameroon. The new species is the second species in the genus with bicuspid teeth. Furthermore, it can be distinguished from its congeners by a combination of characters, such as the absence of accessory teeth, the length and shape of the muscular oesophagus, position of the nerve ring, deirids and excretory pore in relation to the muscular oesophagus, the position of the vulva, spicule length and the shape of the female tail. Additionally, based on new material, detailed morphological descriptions are provided for C. crocutae and C. pardalis whose original descriptions were based on fragmented material. The material from Felis lybica, currently deposited as C. subaequalis, is described as C. felinea. First-time scanning electron micrographs are presented for the 4 species confirmed in African carnivores.

The first find of the pond bat <i>Myotis dasycneme</i> (Boie, 1825) in Stavropol Territory and western Caucasus, Russia

The aim of the work was to describe the discovery of a pond bat Myotis dasycneme (Boie, 1825) in the vicinity of Zheleznovodsk, Stavropol Territory, Russia in August 2023.We examined the Letnei Merzloti Cave, an artificial tunnel about 400 metres long with small dead‐end caverns. The pond bat was found in a small dead‐end cavern. This is the first find of this species in the Stavropol region and the third find in the Caucasus.The first finds of the pond bat were made in the Western Caucasus in 1999 and 2003. This find provides more data about a small population of pond bats in the Caucasus. It is noteworthy that this species of bat (M. dasycneme), together with M. daubentonii, are the only known natural wild hosts of the Europian bat lissavirus virus type 2 in Europe. Given the fact that bats are considered natural hosts of all types of coronaviruses, and that the pond bat previously evidenced the circulation of both alpha and beta coronaviruses in the European population (Germany, the Netherlands), we must be aware of the potential of this species as a reservoir of pathogenic zoonotic coronaviruses.

The six-spotted spider mite, Eotetranychus sexmaculatus (Riley) (Trombidiformes: Tetranychidae) in Australia, New Zealand, Japan and USA: a revised morphological and molecular-based concept, synonyms, and related species

Based on morphological and molecular evidence, Eotetranychus asiaticus Ehara is confirmed as a junior synonym of E. sexmaculatus (Riley). Eotetranychus queenslandicus Manson differs to E. sexmaculatus in some morphological characters states, and currently there is insufficient evidence to confirm if it is also a junior synonym. We therefore propose that it remains a valid species until fresh material can be collected from the type host (Codiaeum variegatum (L.) A.Juss.; Euphorbiaceae) in the type location (Freshwater, Queensland, Australia) for molecular analysis and further comparisons. Eotetranychus sexmaculatus is confirmed as present in Australia and New Zealand. Our analyses indicate that specimens identified as E. sexmaculatus from avocado (Persea americana Mill.; Lauraceae) in Western Australia and New Zealand, and specimens of E. asiaticus from the type host (Ficus erecta Thunb.; Moraceae) and type location (Tomigusuku, Okinawa, Japan) are conspecific with specimens of E. sexmaculatus recently collected from the type host (Citrus sp.; Rutaceae) and type location (Florida, USA), with 0–3.6% divergence in a fragment (451 bp) of cytochrome oxidase subunit I (COI), and 0–0.3% in the ribosomal internal transcribed spacer II (ITS2) gene. Herein we redefine E. sexmaculatus, providing a revised diagnosis, notes on leg chaetotaxy, and variation in the shape of the aedeagus—which is a keystone feature critical for determining species boundaries of spider mite species that have males. Our findings also reinforce the potential of the eupathidion on the palptarsus suζ (i.e. the spinneret) for species diagnoses.

A new weevil species, Larinus atillai sp. nov. (Coleoptera: Curculionidae) from western Turkey

The new species Larinus atillai sp. nov., associated with the Turkish endemic plant Jurinea pontica Hausskn. & Freryn, is described from western Turkey. The new species is closely related to Larinus idoneus Gyllenhal, 1835. Digital images of morphological characters, habitat of type locality, host plant and adults are presented.

Aceria spp. (Acari: Eriophyidae) associated with Amaranthaceae around the world with description of two new species</p >

During field surveys of eriophyoid mites in Razavi and North Khorasan provinces (Iran) in summer 2023, two new Aceria spp. (Acari: Eriophyoidea: Eriophyidae) on Amaranthaceae plants were discovered, illustrated and described: Aceria sodae sp. nov. on Soda rosmarinus (Bunge ex Boiss.) Akhani and Aceria esfarayeniensis sp. nov. on Salsola arbusculiformis Drobow. Furthermore, a list of Aceria spp. on Amaranthaceae species around the world, their type host plants and their relationship to hosts are provided.

Description of Discocotyle ciray n. sp. (Monogenea: Discocotylidae) from Parahucho perryi (Brevoort) from Hokkaido, Japan, with a redescription of D. sagittata (Leuckart, 1842).

Discocotyle sagittata (Leuckart, 1842) (Monogenea: Discocotylidae) is redescribed, based on specimens collected from the type host, Salmo trutta Linnaeus, from the type locality, Freiburg, Germany, supplemented with specimens from S. trutta and rainbow trout, Oncorhynchus mykiss (Walbaum) reared in an Austrian aquarium. The diagnosis of the genus Discocotyle Diesing, 1850 is emended. Discocotyle ciray n. sp. is described, based on immature, preadult and adult specimens from the salmonid, Parahucho perryi (Brevoort) at Eniwa, Hokkaido, Japan. Adult specimens of the new species were about twice as large as those of D. sagittata from S. trutta. When the type specimens of D. ciray n. sp. were examined together with museum specimens from P. perryi at Tsurui, Hokkaido, the body and clamp sizes were positively correlated to the host size. Their measurements from a smaller P. perryi at Tsurui overlapped with those of D. sagittata, showing that these size differences were not suitable differentiating keys. Discocotyle ciray n. sp. can be separated from D. sagittata by the morphologies of the female genital system (relatively anteriorly positioned ovary, short joint vaginal duct and much more strongly winding uterus). The genetic distances of COI mtDNA sequence between D. ciray n. sp. and D. sagittata were 18.0-18.6%. These remarkable genetic divergences also supported the distinct taxonomic status of D. ciray n. sp.

Abstract A084: AMH paracrine signaling between cancer and mesothelial cells modulates the ovarian tumor immune microenvironment

Abstract A084: AMH paracrine signaling between cancer and mesothelial cells modulates the ovarian tumor immune microenvironment

Revisiting the type material of two African Diplozoinae (Diplozoidae: Monogenea), with remarks on morphology, systematics and diplozoid specificity.

The morphological characterisation of Diplozoidae spp. is highly reliant on the details of the sclerotised components of the hooks and clamps in the haptor. Only six species of Paradiplozoon (Diplozoinae) have been described from Africa, four of which have adequate morphological and even comparative ITS2 rDNA data available. However, the descriptions of Paradiplozoon ghanense (Thomas, 1957) and Paradiplozoon aegyptense (Fischthal & Kuntz, 1963) lack essential taxonomic information, specifically the details for their haptoral sclerites. As such, all available material from museum collections for these two species were studied using light microscopy to supplement the original morphometric descriptions. The holotype and paratypes of P. aegyptense were studied, but only voucher material for P. ghanense could be sourced. However, this voucher material for P. ghanense was deposited by the species authority and bore a striking resemblance to the illustrations and collection details from the original description. They were thus identified as the type series for the taxon, with a lectotype and paralectotype designated. Both P. ghanense and P. aegyptense could be readily distinguished from other taxa based on the supplementary data generated here, supporting their distinctness. The haptoral sclerites of P. aegyptense were most similar to those of Paradiplozoon krugerense Dos Santos & Avenant-Oldewage, 2016, also described from Labeo spp., while the sclerites of P. ghanense were most similar to Paradiplozoon bingolense Civáňová, Koyun & Koubková, 2013 and Paradiplozoon iraqense Al-Nasiri & Balbuena, 2016. Additionally, a voucher of P. aegyptense collected from the alestid type host of P. ghanense was reidentified as the latter species here. This greatly simplified the known host specificity for Paradiplozoon spp. in Africa, with P. aegyptense now exclusively reported from Cypriniformes (Cyprinidae and Danionidae), and P. ghanense restricted to Characiformes (Alestidae). The occurrence of all diplozoids from non-cyprinoid hosts was also investigated and several records of diplozoids occurring on non-cyprinoid hosts were collated and scrutinised. Excluding the two instances of diplozoids described and exclusively occurring on Characiformes fishes (P. ghanense and Paradiplozoon tetragonopterini (Sterba, 1957)), most other non-cyprinoid collections appear sporadic and unsubstantiated, but warrant further investigation supported by diligent taxonomic data. Even though the morphometric descriptions of both P. ghanense and P. aegyptense were fully reported on here, additional material will be needed to study their genetic profiles and phylogeny.

A revision of the trichostrongylid nematode Cooperia Ransom, 1907, from deer game: recent integrative research confirms the existence of the ancient host-specific species Cooperia ventricosa (Rudolphi, 1809).

The trichostrongylid roundworms of the genus Cooperia, which are important in veterinary medicine, currently comprise 19 valid species that parasitize the small intestine of both free-living and domestic ruminants. Only four Cooperia spp. have been reported in Europe, namely C. oncophora, C. punctata, C. curticei and C. pectinata. In 2018-2022, 25 red deer (Cervus elaphus) and 30 sika deer (Cervus nippon) of both sexes and various ages from several remote locations in the Czech Republic were parasitologically examined. Intestinal nematodes of the genus Cooperia were found only in two northern regions. Using the globally recognized key book on trichostrongylid nematodes, they were preliminarily identified as C. pectinata. However, a molecular analysis of cox2 and ITS rDNA gene sequences revealed that Cooperia sp. parasitizing Czech deer is a separate taxon that is more closely related to C. oncophora than to C. pectinata. A subsequent morphological analysis and literature survey confirmed the independence of deer Cooperia sp., which is similar but not identical to bovid C. pectinata. Previous long-term correct identifications of bovid C. pectinata and misidentifications of deer Cooperia species were caused by a fundamental error in the key book mentioned above. Interestingly, the ancient trichostrongylid nematode Strongylus ventricosus from the type host red deer (Cervus elaphus) shot near Greifswald (Germany) was described by Rudolphi in 1809. Rudolphi's type material (one male and four females) was deposited in the Museum für Naturkunde (Berlin). Later, the ancient species S. ventricosus was taken as a synonym for various Cooperia spp. Our current re-examination of the type male indicated that there is a relatively good agreement with our new material from Czech deer regarding the most important characteristics of S. ventricosus (i.e., the shape and size of the male spicules); however, Rudolphi's type material is in rather poor condition. The suggested resurrection of the deer Cooperia sp. in this study as Cooperia ventricosa (Rudolphi, 1809) requires verification by collecting and analyzing new nematode material from the type locality near Greifswald.

T7 phage-assisted evolution of riboswitches using error-prone replication and dual selection

Leveraging riboswitches, non-coding mRNA fragments pivotal to gene regulation, poses a challenge in effectively selecting and enriching these functional genetic sensors, which can toggle between ON and OFF states in response to their cognate inducers. Here, we show our engineered phage T7, enabling the evolution of a theophylline riboswitch. We have replaced T7’s DNA polymerase with a transcription factor controlled by a theophylline riboswitch and have created two types of host environments to propagate the engineered phage. Both types host an error-prone T7 DNA polymerase regulated by a T7 promoter along with another critical gene—either cmk or pifA, depending on the host type. The cmk gene is necessary for T7 replication and is used in the first host type for selection in the riboswitch's ON state. Conversely, the second host type incorporates the pifA gene, leading to abortive T7 infections and used for selection in the riboswitch’s OFF state. This dual-selection system, termed T7AE, was then applied to a library of 65,536 engineered T7 phages, each carrying randomized riboswitch variants. Through successive passage in both host types with and without theophylline, we observed an enrichment of phages encoding functional riboswitches that conferred a fitness advantage to the phage in both hosts. The T7AE technique thereby opens new pathways for the evolution and advancement of gene switches, including non-coding RNA-based switches, setting the stage for significant strides in synthetic biology.

Boron‐ and Silane‐Based Electron Transport–Type Host Materials for Long‐Lifetime Blue Phosphorescent Organic Light‐Emitting Diodes

AbstractDeveloping new host materials is crucial to enhance the performance of blue organic light‐emitting diodes (OLEDs), but achieving long operational lifetimes for OLEDs has been challenging. In this study, boron‐ and silane‐based electron transport–type (n‐type) host materials, 5,9‐dioxa‐13b‐boranaphtho[3,2,1‐de]anthracen‐7‐yltriphenylsilane (BO‐pSi) and 2,12‐bis(triphenylsilyl)‐5,9‐dioxa‐13b‐boranaphtho[3,2,1‐de]anthracene (BO‐2mSi), derived from boron‐ and oxygen‐based 5,9‐dioxa‐13b‐boranaphtho[3,2,1‐de]anthracene (DOBNA) are developed. The DOBNA derivatives are modified with a triphenylsilyl blocking group to alleviate intermolecular interactions arising from the planar structure of DOBNA. The DOBNA derivatives maintain high triplet energy even in the solid state and show thermally activated delayed fluorescence features with electron transport properties. BO‐pSi is used as an n‐type host and exhibits a long operational lifetime of ≈5000 h up to 50% of the initial luminance of blue phosphorescent OLEDs. Furthermore, BO‐2mSi demonstrates a high external quantum efficiency of 7.1%, a small full width at half maximum of 33 nm, and a pure‐violet color coordinate of (0.16, 0.02) while maintaining color purity even at high doping concentrations up to 50 wt%.