Summary The new species, Scutellonema viazi n. sp., isolated from a potato field in Chahi sub-county, Kisoro district, southwestern Uganda, is described using light and scanning electron microscopy, along with three molecular markers ( COI of mtDNA, 18S rRNA and D2D3 of 28S rRNA). Detailed morphological illustrations were produced as edited pencil-only drawings, without (digital) inking. This new species is characterised by females with a moderately small body size of 0.5-0.65 mm; an offset lip region with a cephalic framework bearing 3 distinct lip annules; a basal lip annule divided into six regular blocks; a robust stylet measuring 22-24 μ m; lateral field formed by four incisures areolated anteriorly and posteriorly and terminate at the scutellum, posterior areolations extending beyond the scutellum arranged in a pattern resembling ‘foot toes’; and the absence of males. Phylogenetic analyses of the molecular markers demonstrated a close relationship between the new species and morphologically similar species, Scutellonema brachyurus , S. afribrachyurus and S. truncatum , yet S. viazi n. sp. consistently formed a distinct phylogenetic lineage across all analysed molecular markers. The high population density of 100-120 S. viazi n. sp. per 100 ml of soil, combined with the polyphagous nature of Scutellonema species, suggests that this new species may pose a significant pest threat to potato crops, highlighting the need for studies on its pathogenicity.

A population of Meloidogyne luci, previously detected during a 2021 survey of nematodes associated with chickpea in Ethiopia, was maintained on tomato plants and characterised through morphological analysis, multiple molecular markers and complete mitogenome sequencing. Sequence comparison and phylogenetic analyses of the D2-D3 region of the 28S rDNA, ITS rDNA, and mtDNA (Nad5, cox2 and cox1) revealed limited resolution in distinguishing M. luci from closely related species such as M. ethiopica, M. inornata and M. hispanica, underscoring the challenges of differentiating these taxa using partial gene sequences. Complete mitogenome sequencing yielded an 18 702 bp genome with 99.9% identity to the M. luci reference mitogenome. The genome comprised 11 open reading frames, 8 tRNAs, 2 rRNAs, and additional repeat regions, including extra genes such as atp6 and trnM. A host status test confirmed the susceptibility of the chickpea cultivar 'Arerti' to M. luci, indicating that this highly polyphagous nematode poses a potential threat to chickpea production in Ethiopia.

Ginger (Zingiber officinale Rosc.) is an important spice crop in Ethiopia, valued for culinary and medicinal uses. However, production is constrained by several pathogens, including bacterial wilt, with disease incidence reaching up to 95%. Symptomatic plants showed yellowing, wilting, and rhizome rot, symptoms typical of bacterial wilt caused by R. solanacearum (Yu et al., 2003). A field survey conducted during the 2022 cropping season (August - November) assessed the incidence of bacterial wilt in eight key production districts of the former Southern Nations, Nationalities, and Peoples’ Region, Ethiopia (5°00′ - 8°00′ N, 35°00′ - 39°00′ E). Ginger rhizomes were collected for pathogen isolation. Samples were surface sterilized in 1% NaOCl for 5 min, rinsed with sterile distilled water, and aseptically sectioned. Tissues from the margin between healthy and diseased areas were macerated and streaked onto nutrient agar, incubated at 28 - 30°C for 24 - 48 h. Colonies were purified and stored at -80 °C. Enterobacter isolates formed creamy-white colonies, whereas Serratia isolates produced reddish colonies. The 16S rRNA gene was amplified using primers 27F/1492R and sequenced (Li et al., 2010). BLASTn analysis identified 15 isolates as Enterobacter and 10 as Serratia. For species-level identification, the hsp60 and rpoB genes were analysed (Hoffmann & Roggenkamp, 2003; Miyoshi-Akiyama et al., 2013; Mollet et al., 1997). Based on hsp60 sequences, six isolates were identified as E. mori (PZ362820, PZ405498 - PZ405502; 287 bp) showed 98.3% similarity to PQ567000 and clustered in the same clade, while four S. marcescens isolates (PZ371310 - PZ371313; 300 bp) showed 100% similarity to KT992365 and grouped in the same clade. Similarly, rpoB analysis confirmed E. mori (PZ371300; 592 bp) with 99.3% similarity to OL771192 and OL771193 (PP = 0.53), while sequences PZ405491 – PZ405496 showed 97% similarity to OR555745 (PP = 1). S. marcescens isolates (PZ371302 - PZ371308; 758 bp) showed 99.7% similarity to KT992367 (PP = 0.99). Pathogenicity tests were conducted on tissue culture-derived variety “Boziab” ginger seedlings grown in sterilized sandy soil under greenhouse conditions. At the four-leaf stage, plants were inoculated at the stem base with 6 ml bacterial suspension (1 × 10⁸ CFU/ml) using a sterile syringe, while control plants received an equal amount of sterile distilled water, with three replicates per treatment. Symptoms were assessed weekly. Plants inoculated with E. mori and S. marcescens developed wilting symptoms consistent with those observed in the field, whereas control plants remained asymptomatic. Sequence analysis of the 16S rRNA, hsp60 and rpoB genes also confirmed the re-isolated bacteria as E. mori and S. marcescens. This contrasts with earlier reports attributing ginger bacterial wilt to R. solanacearum without molecular confirmation (Hunduma et al., 2016). This is the first report of E. mori and S. marcescens causing bacterial wilt of ginger in Ethiopia and Africa. This study expands the known diversity of pathogens associated with ginger wilt and underscores the importance of accurate pathogen identification. The practice of in situ storage of ginger planting material by farmers in the study area may contribute to increase the risk of bacterial disease outbreaks by prolonging exposure to soil-borne pathogens, highlighting the need for integrated disease management, including disease-free planting material and strict field sanitation.

This study evaluated different approaches for detecting grapevine fanleaf virus (GFLV) in its nematode vector, Xiphinema index, using reverse transcription polymerase chain reaction (RT-PCR). Four sample preparation strategies were compared, each based on a distinct approach and tested under identical conditions. Two approaches involved RNA extraction prior to RT-PCR: column-based RNA extraction (using the RNeasy Plant Mini Kit) and magnetic bead-based RNA extraction (using the MagMAX RNA Isolation Kit). The other two methods were tested without RNA extraction prior to RT-PCR: direct RT-PCR and brief heat treatment. Samples containing one, two or five nematodes from three different vineyards were analysed to assess the effect of sample size on the efficiency of GFLV detection in X. index. Transmission electron microscopy (TEM) confirmed the presence of GFLV-like particles in the anterior region of individual adult females of X. index, supporting the molecular detection results. Among the tested methods, column-based RNA extraction using the RNeasy Plant Mini Kit showed the highest detection probability and most consistent performance under the conditions evaluated, including samples containing one or two adult females of X. index. Detection success increased with higher nematode numbers, with a more pronounced effect observed for methods without prior RNA extraction. These results demonstrate that both sample preparation strategy and nematode number influence GFLV detection efficiency in vector populations and highlight the importance of optimised sample preparation and sampling strategies for reliable GFLV detection, with potential applications in vineyard monitoring, replanting and phytosanitary management.

The root-knot nematode, Meloidogyne javanica, is one of the most damaging plant-parasitic nematodes, affecting chickpea and causing substantial yield losses worldwide. The damage potential and population dynamics of this nematode in chickpea in Ethiopia have yet to be investigated. In this study, six chickpea cultivars were tested using 12 ranges of initial population densities (Pi) of M. javanica second-stage juveniles (J2): 0, 0.125, 0.25, 0.5, 1, 2, 4, 8, 16, 32, 64 and 128 J2 (g dry soil)-1 in a controlled glasshouse pot experiment. The Seinhorst yield loss and population dynamics models were fitted to describe population development and the effect on different measured growth variables. The tolerance limit (TTFW) for total fresh weight ranged from 0.05 to 1.22 J2 (g dry soil)-1, with corresponding yield losses ranging from 31 to 64%. The minimum yield for seed weight (mSW) ranged from 0.29 to 0.61, with estimated yield losses of 71 and 39%. The 'Haberu' and 'Geletu' cultivars were considered good hosts, with maximum population densities (M) of 16.27 and 5.64 J2 (g dry soil)-1 and maximum multiplication rate (a) values of 6.25 and 9.23, respectively. All other cultivars are moderate hosts for M. javanica; therefore, it is crucial to initiate chickpea-breeding strategies to manage the tropical root-knot nematode M. javanica in Ethiopia.

Distinguishing Scutellonema species based on morphology alone is particularly challenging, especially within the S. brachyurus complex. Although Type A (America, Europe, Asia) and Type B (Africa) are geographically isolated and exhibit clear molecular divergence, their morphological differentiation has remained ambiguous. However, a newly compiled dataset, integrating comprehensive morphological and molecular data from multiple crops and countries, with a focus on finger millet populations in Kenya, provides stronger evidence for their separation. Molecular analysis of the D2-D3 region of 28S rDNA and COI of mtDNA confirmed that Type B represents a distinct species, with species delimitation methods (bPTB, GMYC and Rosenberg's PAB) supporting this distinction. A combination of morphological traits such as the number of lip annuli and basal lip blocks, secretory-excretory pore position, c ' ratio, tail length and male stylet length, c and o ratios, further differentiates the two species. Scutellonema brachyurus Type B population is described as Scutellonema afribrachyurus n. sp. and is characterised by a lip region with usually three (exceptionally five) annuli and basal lip annulus with 8-20 blocks, stylet length of 21-32 mu m, ratio a = 20-34, ratio c ' = 0.5-1.4, S-E pore located rarely opposite the middle to mostly posterior part of the pharyngeal lobe, lateral field areolated at scutellum level, spermatheca small, rounded and empty, tail bluntly rounded, and dorsally convex with 9-17 annuli.

The phylum Nematoda represents one of the most cosmopolitan and abundant metazoan groups on Earth. In this study, we reconstructed the phylogenomic tree for phylum Nematoda. A total of 60 genomes, belonging to 8 nematode orders, were newly sequenced, providing the first low-coverage genomes for the orders Dorylaimida, Mononchida, Monhysterida, Chromadorida, Triplonchida, and Enoplida. The resulting phylogeny is well-resolved across most clades, with topologies remaining consistent across various reconstruction parameters. The subclass Enoplia is placed as a sister group to the rest of Nematoda, agreeing with previously published phylogenies. While the order Triplonchida is monophyletic, it is not well-supported, and the order Enoplida is paraphyletic. Taxa possessing a stomatostylet form a monophyletic group; however, the superfamily Aphelenchoidea does not constitute a monophyletic clade. The genera Trichinella and Trichuris are inferred to have shared a common ancestor approximately 202 millions of years ago (Ma), a considerably later period than previously suggested. All stomatostylet-bearing nematodes are proposed to have originated ~305 Ma, corresponding to the transition from the Devonian to the Permian period. The genus Thornia is placed outside of Dorylaimina and Nygolaimina, disagreeing with its position in previous studies. In addition, we tested the whole genome amplification method and demonstrated that it is a promising strategy for obtaining sufficient DNA for phylogenomic studies of microscopic eukaryotes. This study significantly expanded the current nematode genome dataset, and the well-resolved phylogeny enhances our understanding of the evolution of Nematoda.

Summary The ultrastructure of immature and mature spermatozoa, as well as the sperm components within the oocyte following fertilisation and gamete fusion, are investigated in the free-living marine nematode, Pontonema vulgare. Immature spermatozoa from the testis exhibit a stellate nucleus with a nuclear envelope surrounding poorly condensed chromatin. The filamentous sperm cytoplasm contains minute mitochondria and osmiophilic membranous organelles (MO) with a vacuolated structure. Mature spermatozoa found in the uterus are amoeboid cells, polarised into a pseudopod without organelles, while a main cell body includes a nucleus, mitochondria and MOs. The nucleus in mature sperm becomes lobate, and a continuous nuclear envelope surrounds condensed chromatin. Numerous small MOs remain as osmiophilic vesicles of vacuolated structure, lacking contact with the sperm plasmalemma. The prominent pseudopod, filled with parallel arrays of fibres, facilitates the amoeboid motility of the spermatozoon. Observations of spermatozoa within newly fertilised oocytes in P. vulgare align with findings from several studied parasitic nematodes regarding gamete fusion. Within the cortical ooplasm, sperm components form a cluster that includes the nucleus, mitochondria and MOs. Observations of P. vulgare spermatozoa in the female gonoduct confirm key features of the oncholaimid sperm pattern previously described. The presence of a nuclear envelope in spermatozoa represents an important plesiomorphic trait conserved in all enoplid nematodes. This nuclear envelope, retained even within the fertilised oocyte, underscores the differentiation of enoplids from all other nematode clades. Furthermore, the simplified MOs, which remain intact in the mature spermatozoa of P. vulgare and are transferred into the oocyte during fertilisation, may be regarded as apomorphic ultrastructural features characteristic of the Oncholaimidae family.

The transmission and retention of the bacterial symbiont Photorhabdus laumondii during endotokia matricida in Heterorhabditis bacteriophora were examined by transmission electron microscopy of first-stage juveniles (J1), pre-dauer juveniles (J2d), dauer juveniles (DJ), and hermaphrodites. A newly developed method was applied specifically for the fixation and cutting of the J1 stage. Bacteria were present in all developmental stages, except J1. In the J2d and young DJ stages symbiont cells were localised within the cardia, while in fully-developed infective DJ they were observed to divide in the intestinal lumen. In hermaphrodites, bacteria were found in vacuole-like structures in the terminal cells of the intestine near the rectum as well as throughout the intestine. The density of the bacterial cells varied considerably between stages, being lower in J2d than in young DJ. Prolonged storage of DJ resulted in degradation of bacterial cell morphology. These findings on bacterial retention across life stages sheds light on bacterial transmission and retention mechanisms during endotokia matricida in H. bacteriophora.

This study evaluated macropropagated plantlets for nematode resistance screening in Musa spp. We aimed to determine the optimal timing for assessing resistance to Radopholus similis and Meloidogyne arenaria in the plantain cultivar 'Agbagba' at 30-, 60-, and 90-days post-inoculation (DPI). Additionally, we tested different substrates for early-stage screening at 7 DPI. Results indicated that 60 DPI is optimal for resistance screening against R. similis due to significant root damage, while M. arenaria reproduction peaked at 90 DPI without extensive root deterioration. The sand-absorbent polymer (SAP) substrate was most effective for early nematode penetration. Using these findings, we assessed five Musa genotypes at 60 DPI; 'SH 3142' and 'Pisang Jari Buaya' showed resistance to R. similis, 'Agbagba' was susceptible, 'Yangambi KM5' was unexpectedly susceptible, and 'Pisang Lilin' showed intermediate resistance. This study highlights that macropropagated plantlets can be used as an effective method for rapid preliminary resistance screening in Musa spp.

Soybean yields in Ethiopia remain below the global average due to various biotic and abiotic challenges. Plant-parasitic nematodes (PPN) severely reduce yields; however, data on their occurrence, distribution, and diversity in Ethiopia remain scarce. In 2021, a survey conducted across 28 localities in ten major soybean-producing districts in southwest Ethiopia identified seven genera of plant-parasitic nematodes: Helicotylenchus, Hoplolaimus, Meloidogyne, Pratylenchus, Rotylenchulus, Rotylenchus and Scutellonema, and four families: Criconematidae, Heteroderidae, Hoplolaimidae and Pratylenchidae. Molecular analyses using markers such as D2D3 of 28S rDNA, ITS of rDNA, COI and Nad5 of mtDNA revealed the presence of M. javanica, M. hapla, P. goodeyi, Rotylenchulus borealis and S. clathricaudatum. In the five selected districts, Meloidogyne hapla was the most widely distributed root-knot nematode species, identified in 67% (18 out of 27) of the M. hapla positive samples collected from six localities through molecular analysis. Scutellonema clathricaudatum was recorded for the first time associated with soybean, while M. hapla and R. borealis are reported for the first time in Ethiopian soybean fields. These findings provide valuable insights for developing targeted nematode management strategies to enhance soybean productivity.

-Comprehensive surveys in nine coffee-growing counties in Kenya, involving 53 farms and comprising 116 soil and 63 root samples, revealed a total of 12 genera of plant-parasitic nematodes, including: Meloidogyne, Paratylenchus, Pratylenchus, Helicotylenchus, Rotylenchus, Rotylenchulus, Scutellonema, Trophotylenchulus, Xiphinema, Trichodorus, Aphelenchoides and Hemicycliophora. Meloidogyne was the most abundant genus, with densities of up to 210 juveniles (100 ml soil)-1. Morphological and molecular characterisation enabled the identification of several nematode species including Meloidogyne javanica, M. africana, Rotylenchulus borealis and Trophotylenchulus obscurus. For T. obscurus, the 18S rDNA sequences obtained in this study are the first ever reported for the genus. Additionally, the 18S and D2-D3 of 28S, as well as ITS sequences, marked first for this species. In total, six partial 18S, seven D2-D3 of 28S, four ITS sequences of rDNA, ten COI, and two nad5 gene sequences were generated in this study. In conclusion, our study reveals that our knowledge of plant-parasitic nematode occurrence on important crops even, such as coffee, remains poorly documented and understood, highlighting the potential for new discoveries in such areas.

-A previously undescribed Pratylenchus species obtained from maize and coffee in Kenya was identified utilising morphological, morphometrics, and molecular data from the D2-D3 of 28S, 18S, and ITS rDNA gene sequences. Morphologically, P. mahindii n. sp. is characterised by a female body length of 347-428 mu m, body straight to ventrally curved after fixation, labial margin elevated hemispherical-like, elevated oral opening having mostly three lip annuli, a strong basal plate, a stout stylet of 13.6-16.0 mu m, spermatheca oval with, or sometimes without, round sperms, four lateral lines, and a subcylindrical tail that tapers gradually to a smooth conical tip. The matrix code of Pratylenchus new sp. according to key characteristics following Castillo & Vovlas (2007) is A2, B2, C3, D3, E1, F2, G2, H3, I1/2, J1, K2. Molecularly, based on the phylogeny of the D2-D3 expansion segments of 28S, 18S and ITS of rDNA sequences, P. mahindii n. sp. is distinctly different from all known species with a molecular record, and is most closely related to P. bhattii. This study illustrates the need to conduct more diversity studies based on both morphological and molecular data to uncover potentially neglected species in important crops.

The new nematode species Hoplolaimus tuberosus n. sp., isolated from potato rhizosphere in Budwale sub-county, Mbale district, Eastern Uganda, is characterized based on light and scanning electron microscopy alongside four molecular markers. Females of H. tuberosus n. sp. are moderately large (1.2–1.6 mm) and exhibit distinctive morphological features, including an offset lip region with 4–5 lip annuli, a basal lip annule divided into 10–12 irregular blocks, a robust stylet (45–50 μm), a variable lateral field, characterized by one incisure (zigzag longitudinal line formed by anastomoses) anteriorly and posteriorly, and 2–3 irregular, incomplete striae at mid-body, a secretory-excretory pore positioned anterior to the hemizonid, 6 gland nuclei, and a hemispherical to bluntly rounded tail with 8–10 annuli. Males are slightly smaller at 1.0–1.3 mm, have a basal lip annule divided into 2–4 blocks and relatively long spicules (46–58 μm). Phylogenetic analyses of COI mtDNA, ITS-rRNA, 18S-rRNA and D2D3 of 28S-rRNA demonstrated a close relation of the new species with morphologically similar species (Hoplolaimus columbus, Hoplolaimus indicus, Hoplolaimus seinhorsti, Hoplolaimus dubius and Hoplolaimus pararobustus) yet H. tuberosus n. sp. had in all analyses a distinct phylogenetic position. The population density of 50–75 H. tuberosus n. sp. per 100 ml of soil, combined with the polyphagous nature of related Hoplolaimus species, suggests that this new species could pose a significant pest threat to potato crops, warranting further pathogenicity studies.

Plant-parasitic nematodes (PPNs) are major pathogens of fruit trees globally, causing substantial economic losses. In Kenya, research on papaya has focused primarily on viral diseases, particularly those caused by papaya ringspot virus, with no previous reports of PPNs occurrence. This study aimed to characterise the diversity of PPNs and FLNs in papaya fields in Elgeyo-Marakwet County, Kenya, and to assess the associated soil health status. Special emphasis was placed on evaluating FLNs as bioindicators of soil health. Using the Baermann tray method, nematodes were extracted from 64 composite root and soil samples collected across 12 papaya fields in Elgeyo-Marakwet County. PPNs were identified to the genus level, with root-knot (RKN) Meloidogyne species identified by comparing their sequences with reference sequences and analysed using the PPNID tool. The FLNs were classified to the family level and analysed using NINJA software to assess soil health. Four PPN genera and six FLN families were identified, with Meloidogyne javanica being the only RKN, representing the first PPN report in papaya in Kenya. This raises concerns about potential interactions between M. javanica and viral pathogens, which could increase the incidence and severity of papaya ringspot disease. Metabolic footprint stress diagram analyses revealed fertile, mature soils capable of regulating opportunistic organisms, including PPNs. Understanding soil health and nematode composition is essential for developing sustainable nematode management strategies to increase papaya yields.