Morphological and molecular characteristics of Geocenamus longus and the first report of G. brevidens from a karst cave (Nematoda: Merliniidae Siddiqi, 1971).

The taxonomic status of stunt nematodes remains under investigation. Many nematode species belonging to the subfamily Merliniinae still await for more detailed studies, especially for the analyzes on the molecular level. In the presented work, two nematode species belonging to this subfamily were investigated. Characteristics of Geocenamus longus were expanded on the morphological and the rDNA- and mtCOI-derived molecular data. The mitochondrial sequences are for the first time presented for Merliniinae. Additionally, a bisexual population of G. brevidens was reported and characterized from a new, unique underground environment.

Morphological and molecular characterization of Geocenamus persici n. sp. (Nematoda: Merliniinae) from China.

A new stunt nematode species, Geocenamus persici n. sp. was recovered from the rhizosphere of peach (Prunus persica) in Zhejiang Province, China. This species is characterized by a dome-shaped labial region with six bulging sectors. The lip region is slightly offset from the rest of the body with five annuli; cuticle with over 30 longitudinal striae; stylet slender, 19 to 21 m long; excretory pore at the anterior region of the basal pharyngeal bulb; tail cylindrical, 55 to 79 m long with striated terminus. Males are common. Morphologically, the species is close to G. brevicaudatus, G. chengi, G. conicaudatus, G. quadrifer, G. rugosus, and G. tartuensis. Phylogenetic relationships of the new species placed G. persici n. sp. with other species of subfamily Merliniinae. However, it has a sister relationship with G. chengi. Since the new species is found in the peach plantations, our study will lay a foundation to initiate investigations on the occurrence of stunt nematodes in peach growing areas and will aid the researchers to determine whether this group of nematodes cause peach plantation diseases.

Morphometric and total protein responses in Meloidogyne incognita second-stage juveniles to Nemafric-BL phytonematicide.

After hatch, second-stage juveniles (J2) of root-knot (Meloidogyne species) nematodes could spend at least 12 weeks in soil solutions searching for penetration sites of suitable host plants. The external covering of nematodes, the cuticle, consists of various layers that contain glycoproteins, lipids, soluble proteins (collagens) and insoluble proteins (cuticulins). Generally, cucurbitacins are lipophilic, but there is scant information on how cuticular proteins relate to these complex terpenoids. A study was conducted to investigate the nature and extent of damage post-exposure of J2 to a wide range of Nemafric-BL phytonematicide concentrations. Post-72 h exposure to Nemafric-BL phytonematicide, nematode morphometrics versus phytonematicides exhibited either negative quadratic, positive quadratic, or negative linear relations, with the models explained by significant (P < 0.05) associations (R-squared). Similarly, total proteins versus phytonematicide exhibited significant negative quadratic relations. The principal component analysis indicated that concentration level of 2-4% of Nemafric-BL phytonematicide have the highest impact on the morphometric changes of J2. In conclusion, the nature and extent of damage suggested that Nemafric-BL phytonematicide was highly nematicidal as opposed to being nematostatic, thereby explaining its potent suppressive effects on nematode population densities.

Meloidogyne daklakensis n. sp. (Nematoda: Meloidogynidae), a new root-knot nematode associated with Robusta coffee (Coffea canephora Pierre ex A. Froehner) in the Western Highlands, Vietnam.

The root-knot nematode species Meloidogyne daklakensis n. sp. was discovered on the roots of Robusta coffee (Coffea canephora Pierre ex A. Froehner) in Dak Lak Province, Vietnam. This species is characterized by the females having rounded or oval perineal patterns, smooth, regular, continuous striae, and reduced lateral lines. The dorsal arch is low, rounded and encloses a quite distinct vulva and tail tip. The stylet is normally straight with well-developed and posteriorly sloped knobs. The males have a rounded cap that extends posteriorly into the lip region. The procorpus is outlined distinctly, and is three times longer than the metacorpus. The metacorpus is ovoid, with a strong valve apparatus. The species closely resembles M. marylandi, M. naasi, M. ovalis, M. panyuensis, M. lopezi, M. mali and M. baetica in the perineal pattern of the females, and the morphology of the males and the second-stage juveniles. Nonetheless, it can be differentiated from other species by a combination of morphometric, morphological and molecular characteristics. Phylogenetic analysis was conducted based on the internal transcribed spacer (ITS) and 28S rDNA as well as the region between the cytochrome c oxidase I (COI) and cytochrome c oxidase II (COII) mitochondrial genes. Herein, this nematode is described, illustrated, and designated as a new species, Meloidogyne daklakensis sp. n., based on morphometric, morphological and molecular analyses.

Morphological and molecular characterization of Trophurus wuhuensis n. sp. (Nematoda: Telotylenchinae) from soil associated with Cinnamomum camphora in China.

A new plant nematode species, Trophurus wuhuensis n. sp., was collected from the soil associated with Cinnamomum camphora in Wuhu, Anhui Province, China. The new species is characterized by having a female with a slender body 660.5-801.5 µm in length, stylet 12-14 µm long, knobs directed laterad, lateral field marked by short and scattered grooves, post-vulval uterine sac shorter than vulval body diameter, post-rectal intestinal sac absent, tail cylindroid, terminus with deep wrinkles; and male with a pointed tail terminus and spicules 16-18 µm long. The internal transcribed spacer sequences of ribosomal DNA (ITS rDNA) and partial 18S ribosomal DNA (18S rDNA) from T. wuhuensis n. sp. were amplified and sequenced. A phylogenetic analysis based on sequences of 18S rDNA fragments is given in this study.

Molecular characterization and species delimiting of plant-parasitic nematodes of the genus Pratylenchus from the penetrans group (Nematoda: Pratylenchidae).

Root-lesion nematodes of the genus Pratylenchus are an important pest parasitizing a wide range of vascular plants including several economically important crops. However, morphological diagnosis of the more than 100 species is problematic due to the low number of diagnostic features, high morphological plasticity and incomplete taxonomic descriptions. In order to employ barcoding based diagnostics, a link between morphology and species specific sequences has to be established. In this study, we reconstructed a multi-gene phylogeny of the Penetrans group using nuclear ribosomal and mitochondrial gene sequences. A combination of this phylogenetic framework with molecular species delineation analysis, population genetics, morphometric information and sequences from type location material allowed us to establish the species boundaries within the Penetrans group and as such clarify long-standing controversies about the taxonomic status of P. penetrans, P. fallax and P. convallariae. Our study also reveals a remarkable amount of cryptic biodiversity within the genus Pratylenchus confirming that identification on morphology alone can be inconclusive in this taxonomically confusing genus.

Morphological characterisation of a new and two known species of Ditylenchus Filipjev, 1936 (Nematoda: Anguinidae) from Iran.

Ditylenchus sturhani sp. n. from the rhizosphere of grasses in East Azarbaijan province, Northwestern Iran, is described and illustrated. The new species is characterised by a straight to slightly arcuate body 656-865 µm in length, presence of four incisures in each lateral field, slender stylet 10-12 µm in length, pharyngeal basal bulb offset or slightly overlapping the intestine, post-uterine sac 1.0-1.9 vulval body diameter long and conical tail with finely rounded terminus. Differences with closely related species including D. solani, D. ausafi, D. angustus, D. dipsaci, D. drepanocercus, D. obesus and D. gallaeformans are discussed. In addition, Iranian populations of two known species, D. valveus and D. virtudesae, are morphologically characterised.

Bioactive secondary metabolites with multiple activities from a fungal endophyte.

In order to replace particularly biohazardous nematocides, there is a strong drive to finding natural product-based alternatives with the aim of containing nematode pests in agriculture. The metabolites produced by the fungal endophyte Fusarium oxysporum 162 when cultivated on rice media were isolated and their structures elucidated. Eleven compounds were obtained, of which six were isolated from a Fusarium spp. for the first time. The three most potent nematode-antagonistic compounds, 4-hydroxybenzoic acid, indole-3-acetic acid (IAA) and gibepyrone D had LC50 values of 104, 117 and 134 µg ml-1 , respectively, after 72 h. IAA is a well-known phytohormone that plays a role in triggering plant resistance, thus suggesting a dual activity, either directly, by killing or compromising nematodes, or indirectly, by inducing defence mechanisms against pathogens (nematodes) in plants. Such compounds may serve as important leads in the development of novel, environmental friendly, nematocides.

Description of Basiria birjandiensis n. sp (Nematoda: Tylenchidae) from South Khorasan province with a checklist of the family Tylenchidae Örley 1880 from Iran.

In order to identify plant-parasitic nematodes (family Tylenchidae Örley 1880) associated with Ziziphus zizyphus in Iran, 360 soil and root samples were collected from South Khorasan province during 2012-2014. Herein, a new species of Basiria and several known members of the family Tylenchidae are reported. B. birjandiensis n. sp. is characterized by short body length (584-748 µm [660.6±72.3]), lip region with flat apex, stylet 11-12 µm (11.3±0.5), excretory pore position varying from isthmus level to the middle of the basal bulb (78-91 µm from the anterior end of the body), post-vulval uterine sac 8-14 µm (10.7±1.9) long, filiform tail (151-181 µm, c= 3.7-4.2, c´= 14.3-17.2) and body annuli 0.5-1 µm (0.6±0.1) wide. A checklist of Tylenchidae species from Iran is also presented.

A checklist of the family Pratylenchidae Thorne, 1949 from Iran.

The Family Pratylenchidae comprises nematodes that are capable of penetrating and feeding on internal root tissues. The list of Pratylenchidae species known from Iran is presented. The updated species list provides information on their morphometrics, referring to full or partial descriptions, associated plants, geographical distribution and references. The list includes 37 species belonging to five genera. Two species of Pratylenchus (P. sensillatus and P. wescolagricus) are new records for the Iranian nematofauna. Some information on these two and other known species is also provided.

One new and three known species of Geocenamus Thorne & Malek, 1968 (Nematoda: Merliniidae) from Iran.

Soil samples collected from different plants and localities in Iran yielded one new and three known species of the genus Geocenamus with tessellated cuticle. Geocenamus conicaudatus n. sp. is characterised by a hemispherical cephalic region, set-off from the rest of body by a constriction, a slender stylet 17-20 µm long with laterally directed knobs, coarsely annulated cuticle with 32-34 longitudinal striae and a conical tail with smooth, finely rounded terminus. Morphological and molecular studies on the populations of G. paniculoides and G. tartuensis indicated that G. paniculoides may be considered as a valid species. Intraspecific variability of some characters of 30 Iranian populations of G. rugosus were studied. An identification key to 32 valid species of the genus Geocenamus is given.

Rotylenchus castilloi n. sp. (Nematoda: Hoplolaimidae), a new species with long stylet from northern Iran.

Rotylenchus castilloi n. sp., a new bisexual species is described and illustrated based on morphological, morphometric and molecular data. The new species is characterised by having a hemispherical, continuous lip region with an irregular corncob-like appearance under SEM, very long stylet (62-68 µm), vulva located at 49.7-62.2% of body length from anterior end, with a protruding double epiptygma, a rounded to convex-conoid (rarely bi-lobed) tail with 8-12 annuli and specific sequences of D2-D3 segments of 28S and ITS1-rRNA genes. Differences between the new species and four other species of the genus (R. mesorobustus, R. cazorlaensis, R. magnus and R. jaeni) are discussed. Morphologically, the new species can be separated from these species mostly by its body length, lip region characters, stylet length and location of phasmid. Phylogenetic analyses using 721 bp partial sequences of D2-D3 expansion segments of the 28S and 590 bp ITS1-rRNA genes revealed the new species forming a clade with two isolates of R. eximius and two isolates of R. unisexus, two morphologically unrelated species.

Contribution to a revision of the genus Pratylenchoides Winslow, 1958 (Nematoda: Merliniidae), with redescription of P. erzurumensis Yüksel, 1977 from Iran.

Morphological and morphometric studies were conducted on the populations and paratypes of 14 species of the genus Pratylenchoides, including P. alkani, P. acuticauda, P. arenarius, P. arenicola, P. bacilisemenus, P. crenicauda, P. erzurumensis, P. heathi, P. laticauda, P. ritteri, P. rivalis, P. sheri, P. utahensis and P. variabilis. In addition, P. erzurumensis was redescribed based on a bisexual population from western Iran. The conoid head of males is an additional diagnostic character of this species distinguishing it from the closely related P. laticauda and P. camachoi. Based on detailed study of the main characters, synonymies of P. arenarius with P. bacilisemenus and P. variabilis with P. crenicauda are proposed. Synonymy of P. alkani with P. ritteri is supported also by morphological and biological evidence. Some taxonomic notes are made on some other species of the genus. Finally, a diagnostic compendium and key is provided for species identification. 

Pratylenchus quasitereoides n. sp. from cereals in Western Australia.

Pratylenchus quasitereoides n. sp. is described from Western Australia. It is characterized by 2 external incisures in the head cuticle, 4 lateral incisures at mid body, stylet length 17 µm to 19 µm, V greater than 75%, PUS less than 2 body diameters long and crenate tail terminus. Molecular data confirm the separation of the new species from morphologically similar and sympatric congeners. The host range also differs from P. teres as well as the sympatric P. neglectus, P. thornei and P. penetrans. Reproduction rates on oat and lupin differed between the new species and P. neglectus. The species was originally described as P. teres, but the species concept of P. teres now encompasses a considerable range of different attributes spread over two described subspecies and three variant populations. The new species differs from all these subspecies and populations in at least two characters. It differs from all populations of P. teres teres most notably in having four rather than 6 lateral lines and a more posterior vulva. It differs from P. teres vandebergae in having a longer stylet and longer overlap of the intestine by the oesophageal glands. Characters which can be used under low magnification to separate the new species from the closest sympatric congeners (P. thornei and P. crenatus) are discussed.

Description of Amplimerlinius uramanatiensis sp. n. (Nematoda: Merliniidae) and observations on three other species of the genus from Iran.

A new species of the genus Amplimerlinius is described and illustrated from the rhizosphere of Vitis sp. from Kurdistan province in western Iran. A. uramanatiensis sp. n. is characterized by having seven to eight head annuli up to the end of the outer extension of the cephalic framework, 29-31 µm long stylet and cylindrical-clavate tail with a thin hyaline region (9-11 µm) and smooth terminus. Furthermore, A. paraglobigerus and A. macrurus were identified and intra-specific variability of A. globigerus was studied in detail, based on 21 populations collected from different regions of Iran. A key and diagnostic compendium to the species of the genus is provided.

Morphological and molecular characterization of Zygotylenchus gansuensis n. sp. (Nematoda: Pratylenchinae) from China.

Zygotylenchus gansuensis n. sp. is described and illustrated from the rhizosphere of jujube (Zizyphus jujuba Mill.) based on morphology and molecular analyses. This new species is characterized by a low and flattened labial region with three annuli, stylet 14.1±0.5 (13.0-14.9) µm long, deirids absent, five lateral lines in the vulval region, pharyngeal glands overlapping ventrally or ventrolaterally, V = 56.4±1.6 (54.0-60.8), indistinct spermatheca, subcylindrical tail with smooth and rounded terminus, and males absent. Molecular analyses show that the species has unique partial SSU, LSU D2D3 and ITS rRNA sequences. Phylogenetic relationships of Z. gansuensis n. sp. with other nematodes in Pratylenchinae are analysed using SSU and LSU D2D3.

An updated and annotated checklist of the Dolichodoridae (Nematoda: Tylenchoidea) of Iran.

The list of plant parasitic nematodes of the family Dolichodoridae, known from Iran, is updated. 81 species belonging to 13 genera and three subfamilies are included in the list. Data for 29 species are added, of which seven species viz. Neodolichorhynchus phaseoli, Pratylenchoides crenicauda, P. erzurumensis, P. utahensis, Scutylenchus paniculoides, Trophurus impar and Tylenchorhynchus variannus are new records for the Iranian nematofauna. The list of species, further information on their morphometrics, references, referring to full or partial descriptions, associated plants, geographical distribution and some taxonomic remarks are provided. More detailed studies on some doubtful populations are proposed. The information on the taxonomic position of species in different classification schemes, as well as, the tendency of the species to certain climatic condition or ecological niche are provided. Challenges on the reliable identification of this group of nematodes in Iran are discussed and finally, suggestions were proposed for future studies.

Activation of hatching in diapaused and quiescent Globodera pallida.

The potato cyst nematodes (PCN) Globodera pallida and G. rostochiensis are major pests of potatoes. The G. pallida (and G. rostochiensis) life cycle includes both diapause and quiescent stages. Nematodes in dormancy (diapause or quiescent) are adapted for long-term survival and are more resistant to nematicides. This study analysed the mechanisms underlying diapause and quiescence. The effects of several compounds (8Br-cGMP, oxotremorine and atropine) on the activation of hatching were studied. The measurements of some morphometric parameters in diapaused and quiescent eggs after exposure to PRD revealed differences in dorsal gland length, subventral gland length and dorsal gland nucleolus. In addition, the expression of 2 effectors (IVg9 and cellulase) was not induced in diapaused eggs in water or PRD, while expression was slightly induced in quiescent eggs. Finally, we performed a comparative study to identify orthologues of C. elegans diapause related genes in plant-parasitic nematodes (G. pallida, Meloidogyne incognita, M. hapla and Bursaphelenchus xylophilus). This analysis suggested that it was not possible to identify G. pallida orthologues of the majority of C. elegans genes involved in the control of dauer formation. All these data suggest that G. pallida may use different mechanisms to C. elegans in regulating the survival stage.

Heterodera fengi n. sp. (Nematoda: Heteroderinae) from bamboo in Guangdong Province, China--a new cyst nematode in the Cyperi group.

Heteroderafengi n. sp. is described and illustrated from bamboo (Phyllostachys pubescens Mazel) based on morphology and molecular analyses of rRNA LSU D2D3 region and ITS. This new species belongs to the Cyperi group. Cysts are characterized by prominent vulval cone with ambifenestrate, bifurcate underbridge that is thicker in middle and a 47.0 (40.0-60.0) µm long vulval slit, but without bullae. The second-stage juveniles are characterized by a 23.2 (22.0-24.0) µm long stylet with slightly projected or anteriorly flattened knobs, three incisures in lateral field, a 70.2 (62.5-77.0) µm long tail with bluntly rounded terminus and hyaline portion ca 58.9 (50.0-62.5)% of the tail length. Males are characterized by a 25.1 (24.5-26.3) µm long stylet with rounded knobs sloping posteriorly, four incisures in lateral field, a 29.8 (27.5-31.3) µm long spicule with bifurcate tip. Phylogenetic analysis shows that the species has unique D2D3 and ITS rRNA sequences and RFLP-ITS-rRNA profiles. Heteroderafengi n. sp. is closest to H. elachista in dendrograms inferred from both DNA sequences.