High infection rates of European sea rocket feeder roots by an unknown root-knot nematode were found in a coastal dune soil at Cullera (Valencia) in central eastern Spain. Morphometry, esterase and malate dehydrogenase electrophoretic phenotypes and phylogenetic trees demonstrated that this nematode species differs clearly from other previously described root-knot nematodes. Studies of host-parasite relationships showed a typical susceptible reaction in naturally infected European sea rocket plants and in artificially inoculated tomato (cv. Roma) and chickpea (cv. UC 27) plants. The species is herein described and illustrated and named as Meloidogyne dunensis n. sp. The new root-knot nematode can be distinguished from other Meloidogyne spp. by: (i) perineal pattern rounded-oval, formed of numerous fine dorsal and ventral cuticle striae and ridges, lateral fields clearly visible; (ii) female excretory pore at the level of stylet knobs, EP/ST ratio 1.6; (iii) second-stage juveniles with hemizonid located 1 to 2 annuli anteriorly to excretory pore and long, narrow, tapering tail; and (iv) males with lateral fields composed of four incisures anteriorly and posteriorly, while six distinct incisures are observed for large part at mid-body. Phylogenetic trees derived from distance and maximum parsimony analyses based on 18S, ITS1–5.8S-ITS2 and D2-D3 of 28S rDNA showed that M. dunensis n. sp. can be differentiated from all described root-knot nematode species, and it is clearly separated from other species with resemblance in morphology, such as M. duytsi, M. maritima, M. mayaguensis and M. minor.
histopathology; host-parasite relationships; ITS1; ITS2; Meloidogyne; morphology; new species; phylogeny; ribosomal DNA; root-knot nematode; scanning electron microscopy; taxonomy
Diagnosis of an Argentinean population of Nacobbus sp. infecting sweet pepper (lamuyo) was carried out including morphology, scanning electron microscopy, and molecular studies. In light of our morphometric, molecular and host-range results, we consider the studied population to belong to N. aberrans s. l., and by host range tests the population is assigned to the "sugar beet group." ITS-PCR analysis on individual male and immature female specimens of this population yielded amplification products of approximately 922 bp. RFLP profiles and sequencing of the ITS region revealed that, in addition to the host group, the present population can be assigned to the "Argentina 2" group. Disease development and histopathology were investigated with glasshouse observations using tomato, pepper, sugar beet and potato seedlings exposed to nematode infection for 45 days at 28 ± 2°C. Histopathology of tomato roots confirmed that all immature stages and young females and males are migratory, whereas mature females are obligate sedentary endoparasites. Rather than syncytia, large regions of cortical necrosis and cavities were detected in tomato swellings infected by juveniles. However, syncytia were associated only with adult females. Large root galls, hyperplasia, abnormal proliferation of lateral roots and asymmetry of root structure were common anatomical changes induced by the nematode feeding in tomato roots.
Argentina; false root-knot nematode; histopathology; host-parasite relationships; morphology; PCR-RFLP profiles; quarantine; tomato
A population of the cystoid nematode Meloidoderita kirjanovae was detected parasitizing water mint (Mentha aquatica) in southern Italy. The morphological identification of this species was confirmed by molecular analysis using the internal transcribed spacer 1 (ITS1) and 5.8S gene sequences of nuclear ribosomal DNA (rDNA), which clearly separated it from the closely related species Meloidoderita polygoni. A phylogenetic analysis of M. kirjanovae with species of related genera was conducted using sequences of the D2-D3 expansion segments of the 28S nuclear ribosomal RNA gene. The resulting phylogenetic tree was congruent with trees from an extended dataset for Criconematina and Tylenchida. The basal position of the genus Meloidoderita together with Sphaeronema within the Criconematina clade in this tree may indicate their close relationships. The anatomical changes induced by M. kirjanovae population from Italy in water mint were similar to those reported for a nematode population infecting roots of M. longifolia in Israel. Nematode feeding caused the formation of a stellar syncytium that disorganized the pericycle and vascular root tissues.
histopathology; host-parasite relationships; Mentha aquatica; molecular analysis; morphology; SEM; taxonomy; phylogeny
The influence of temperature and olive root exudates on Heterodera mediterranea egg hatch and the effects of H. mediterranea on the growth of two olive cultivars (Arbequina and Picual) were investigated. Egg hatch occurred over a temperature range of 10 to 30°C and was optimal at 20 to 25°C. There were no differences in egg hatch between sterile deionized distilled water or root exudate dilutions (undiluted, diluted 1:1, and 1:2) of Arbequina and Picual at 20°C. Heterodera mediterranea reproduced on both olive cultivars in growth chambers at 25°C. Soil and root final nematode populations, as well as total number of cysts per plant and reproduction rate, were significantly higher in Arbequina than in Picual. Shoot dry and root fresh weights as well as increases of shoot height, trunk diameter, and numbers of nodes were significantly suppressed by infection with 10,000 eggs + second-stage juveniles/pot in Arbequina but not in Picual.
arbequina; hatching; Olea europaea; olive cyst nematode; pathogenicity; Picual; reproduction; root exudates; Spain; temperature
Phylogenetic analysis of new ribosomal DNA (rDNA) data for Heterodera mediterranea, H. hordecalis, H. carotae, and H. fici from Italy and H. ciceri from Syria, along with published data for other species, showed high bootstrap support for the following relationships: (((((H. carotae H. cruciferae) H. goettingiana) (((H. trifolii H. ciceri) H. mediterranea) ((H. avenae H. latipons) H. fici))) (Cactodera betulae H. hordecalis)) (Globodera rostochiensis G. pallida)). The rDNA sequence data were for the two internal transcribed spacers (ITS1 and ITS2) plus the 5.8S gene between them. These inferred relationships support the classic ''Goettingiana Group'' of H. carotae, H. cruciferae, and H. goettingiana. A clade comprised of Cactodera betulae and H. hordecalis is only distantly related to the other species in the analysis.
Heterodera; Heterodera carotae; Heterodera ciceri; Heterodera fici; Heterodera hordecalis; Heterodera mediterranea; ITS1; ITS2; phylogenetic analysis; ribosomal DNA; 5.8S gene
Hemicycliophora hellenica n. sp. is described and illustrated from a bisexual population found in Filippias, Epirus, Greece, in the rhizosphere of giant reed (Arundo donax) and unidentified aquatic plants along the edge of irrigation canals. Hemicycliophora hellenica n. sp. is characterized by a long stylet (more than 120 µm), body length (L = 1,078-1,634 µm; R = 303-362), and lateral field marked by three lateral lines in females and four in males. The lip region is distinctive in that the female labial disc is oval and offset from the first lip region annule, and protrudes markedly; the male labial disc is very large, offset and rectangular, and protrudes distinctly. Hemicycliophora hellenica n. sp. resembles H. megalodiscus Loof by possession of a strongly protruding labial disc, but differs in having a longer female body, more body annules, longer stylet, and dorsally and ventrally indented head annules. The male labial plate is larger than in H. megalodiscus, and the male has four incisures in the lateral field vs. three in H. megalodiscus.
Criconematoidea; Greece; Hemicycliophora hellenica; morphology; nematode; new species; taxonomy
Syconia ("figs") from Ficus thonningii and adults of its pollinator wasp Elisabethiella stuckenbergi were dissected to elucidate their association with a new species of Schistonchus (Aphelenchoididae). Schistonchus africanus n. sp. is characterized by a short stylet (13-16 μm long); position of the excretory pore opening in both sexes at a level just behind the stylet knobs; and short post-uterine branch, one body-width long. Schistonchus africanus n. sp. parasitizes F. thonningii florets and is transported by the winged females of E. stuckenbergi. Juveniles, females, and males of the nematode were found in the female and male fig florets and in the abdomen of the vector. Nematode populations extracted from female wasps or fig floret tissues did not differ in their morphology. No association was observed with the wingless males of the pollinator wasp.
Agaonidae; Aphelenchoididae; Elisabethiella stuckenbergi; Ficus thonningii; fig; life history; nematode; Schistonchus africanus n. sp.; South Africa
Pratylenchoides hispaniensis n. sp. is described and illustrated from a bisexual population found in a natural habitat at Santa Elena, Jaen, central Spain. Its main distinctive characters are very long esophageal gland lobe (81-117 μm; N' = 51-71) overlapping the intestine 3 to 5 times the body width; lateral field with six incisures; stylet knobs sloping posteriorly; labial disc encircled by the irregular sectors of the first annule; tail cylindrical, extremity annulated, and frequently with a slight dorsal indentation of the hyaline portion at the end of the lateral field. Pratylcnchoides hispaniensis n. sp. appears closely related to P. megalobatus and P. nevadensis. It differs from the former primarily by its longer body length (761-998 vs. 430-621 μm), longer stylet length (20.5-24.4 vs. 18-21 μm), six incisures in the lateral field vs. four for P. megalobatus, and posteriorly sloping stylet knobs vs. rounded or anteriorly flattened knobs in P. megalobatus. It differs from P. nevadensis mainly by the shape of the stylet knobs (sloping in P. hispaniensis vs. rounded in P. nevadensis), length of esophageal lobe (81-117 vs. 34-82 μm), and position of esophageal gland nuclei (all posterior to esophago-intestinal junction in P. hispaniensis vs. at least one nucleus anterior to junction in P. nevadensis).
morphology; nematode; new species; Pratylenchoides hispaniensis; scanning electron microscopy; taxonomy
Rotylenchus graecus n. sp. is described and illustrated from a bisexual population found in Filippias, Epirus, northwestern Greece, in the rhizosphere of ivy (Hedera helix L.) and giant reed (Arundo donax L.) grown on the edge of irrigation canals. Rotylenchus graecus n. sp. is characterized by a lip region with five annules, stylet length of 29-32 μm, vulva position at 53-65%, female tail pointed-conoid with 15-23 annules, and bursa with regularly annulated margins enveloping tail. The new species differs from all other Rotylenchus species with couoid tails in having a greater number of tail annules. Rotylenchus graecus n. sp. appears closely related to R. acuspicaudatus Van den Berg &Heyns, 1974, but differs from it primarily by the greater number of female tail annules (15-23 vs. 13-16), stylet length (29--32 vs. 25.7-28.3 μm), and the less ventrally protruding bursa, which has smooth posterior margins rather than the finger-like appearance of the posterior bursal annules in R. acuspicaudatus.
Greece; Hoplolaimidae; morphology; nematode; new species; Rotylenchus graecus; spiral nematode; taxonomy
The responses of 20 species of ornamental palms and one cycad (Cycas revoluta) to two populations of the reniform nematode, Rotylenchulus reniformis, from southern Florida were studied in two greenhouse experiments conducted in 1989-1991 and 1991-92. Ornamental palms in pots were exposed to initial population densities of 400 and 1,500 R. reniformis/l00 cm³ soil for 16 and 15 months, respectively. Nematode reproduction occurred on Acoelorrhaphe wrightii and Washingtonia robusta, but not on the other palms or the cycad. In both experiments, nematode numbers on A. wrightii and W. robusta were significantly smaller than those on cowpea (Vigna unguiculata), a susceptible host of the nematode used as a control in these experiments. Nematodes surviving in pots containing nonhost palms for 16 months retained infectivity and were able to reproduce on susceptible cowpea in a bioassay. Sections from Washingtonia robusta roots infected by R. reniformis females showed the nematode feeding on syncytia formed by endodermal, pericyclic, and vascular parenchyma cells in a manner similar to that reported for other monocot hosts of the reniform nematode.
Acoelorrhaphe wrightii; Archontophoenix alexandrae; Bismarckia nobilis; Carpenteria acuminata; Caryota mitis; Chamaedorea cataractarum; Chamaerops humilis; Coccothrinax sp.; Cycas revoluta; Florida; histopathology; infectivity; Meloidogyne incognita; nematode; Neodypsis decaryi; N. lastelliana; Phoenix roebelenii; Ptychosperma elegans; Ravenea rivularis; regulatory nematology; reniform nematode; Rhapis excelsa; root-knot nematode; Rotylenchulus reniformis; Sabal palmetto; survival; Syagrus romanzoffiana; Thrinax morrisii; Trachycarpus fortunei; Washingtonia robusta; Wodeyetia bifurcata; Vigna unguiculata
Afenestrata koreana n. sp. collected from roots of bamboo (Phyllostachys pubescens) in Gyeongnam Province in the southern part of the Korean peninsula is described and illustrated. Its primary differentiating characteristics are a globose to subspherical body in adults with a prominent neck and terminal cone, thick cuticle, terminal vulva, and deep vagina. Fenestra, bullae, and underbridge are absent. The anus is on the immediate posterior side of the cone. Superficial small tubercules cover all the terminal cone area. The new species differs markedly from the other two known species in the genus, specifically in having three incisures in the lateral field of juveniles and a shorter stylet length in juveniles and adults. The male is unknown.
Afenestrata koreana n. sp.; bamboo; cyst nematode; Heteroderidae; morphology; nematode; new species; Phyllostachys pubescens; scanning electron microscopy; taxonomy
An abundant female population of a criconematid species identified as Mesocriconema kirjanovae (Andr ssy, 1962) Loof &De Grisse, 1989 is reported from a natural habitat in southeastern Spain. Measurements and morpho-anatomy obtained with light microscopy and scanning electron microscopy are included and compared with previous data on this species.
Criconematidae; Erica sp.; Mesocriconema annulatiforme; M. kirjanovae; M. raskiense; morphology; nematode; ring nematode; scanning electron microscopy (SEM); Spain; taxonomy
Mesocriconema ornicauda n. sp. and Ogma floridense n. sp. are described from two native habitats of central and northwestern Florida. Mesocriconema ornicauda is closest to M. annulatiforme (De Grisse &Loof, 1967) Loof &De Grisse, 1989, but differs by the shorter stylet of the female (43-50 vs. 54-65 μm) and the moderately conoid tail of the male, which is pointed in M. annulatiforme. Ogma floridense is closest to O. hungaricum (Andrassy, 1972) Siddiqi, 1986. Females differ from those of O. hungaricum by the first of two labial annuli being wider, whereas they are subequal in O. hungaricum. Ogma floridense females differ also by entire or bifid cuticular scales, which are consistently divided into two or four projections in O. hungaricum, the shorter body (360-471 vs. 480-550 μm), the shorter stylet (87-98 vs. 95-100 μm), and the more anteriorly located excretory pore (Rex = 17-19 vs. 21-23).
Mesocriconema annulatiforme; M. ornicauda; Florida; morphology; new species; Ogma floridense; O. hungaricum; ring nematode; scanning electron microscopy (SEM); taxonomy
Ogma civellae (Steiner, 1949) Raski &Luc, 1987, O. cobbi (Micoletzky, 1922) Siddiqi, 1986, and O. palmatum (Siddiqi &Southey, 1962) Siddiqi, 1986 are reported in natural habitats in southeastern Spain. Each is briefly described using light microscopy, and the original descriptions are amplified and supplemented by scanning electron microscopy (SEM) observations. Measurements with standard deviations and SEM illustrations are included for each species and compared with previous data.
morphometry; Ogma civellae; O. cobbi; O. palmatum; plant-parasitic nematode; scanning electron microscopy (SEM); Spain; taxonomy
Merlinius paniculoides n. sp. is described from a bisexual Italian population found in northern Italy. This species has a coarsely annulated cuticle with approximately 30 longitudinal striae in addition to the six lateral field incisures; consequently the cuticle appears tessellate. The female tail is subcylindrical with a bluntly, rounded, non-annulated terminus. Merlinius paniculoides shares the tessellate cuticular ornamentation and the offset labial region with M. lenorus (Brown, 1956) Siddiqi, 1970 and M. tartuensis (Krall, 1959) Siddiqi, 1970. It differs from M. lenorus by the higher c and lower c' ratios (c = 16-19 vs. 12-15 and c' = 2.2-2,8 vs. 3.7) and greater number of longitudinal striae (28-32 vs. 24). It differs from M. tartuensis by a fewer number of annuti from stylet knob base to lip constriction (8-9 vs. 21), shorter stylet (19-21 vs. 24 μm), presence of males, and higher c' value (c' = 2.2-2.8 vs. 1.9).
light microscopy (LM); Merlinius paniculoides n. sp.; morphology; new species; scanning electron microscopy (SEM); taxonomy; Telotylenchinae
Most morphological characteristics of three populations of a Tylenchulus sp. from peach roots in Alabama, Arkansas, and Georgia did not differ from those of T. palustris paratypes. However, some mature females differed slightly from those of T. palustris paratypes from Florida. These mature females were more swollen in the posterior portion of their bodies, and they possessed digitate postvulval body sections with round rather than conoid termini. These morphological variants had a wide postvulval section core (PVSC), as do T. palustris paratypes; they did not differ from the paratypes in other characteristics. Second-stage juveniles and males were less morphologically variable and were not different from the paratypes. No males were found in populations from Alabama and Georgia. The Tylenchulus sp. from three peach sites was determined to be T. palustris. This is the first report of T. palustris on an economically important crop.
Alabama; Arkansas; citrus nematode; Georgia; morphological variability; peach; Prunus persica; scanning electron microscopy (SEM); systematics; Tylenchulus palustris; Tylenchulus semipenetrans
A new species of Discocriconemella and the male of Discocriconemella degrissei are described from Minas Gerais state of Brazil. Discocriconemella mineira n. sp. differs from D. discolabia by having a longer stylet (61-71 vs. 35-47 μm) and fewer body annuli (78-88 vs. 155-174), and from D. inarata by the longer stylet (61-71 vs. 51-61 μm) and shorter body length (253-342 vs. 354-486 μm). It differs from D. persae by having a shorter stylet, fewer body annuli, and a shorter post vulval body portion (Rv = 6-7 vs. 14-20). Discocriconemella mineira can be separated from D. degrissei by the head disc which is round in D. mineira and quadrilobate in D. degrissei. Males of D. degrissei resemble those of D. retroversa.
Criconematidae; morphology; SEM; taxonomy
Tylenchulus graminis n. sp. and T. palustris n. sp. are described and illustrated from broomsedge (Andropogon virginicus L.) and pop ash (Fraxinus caroliniana Mill.), respectively. T. graminis resembles T. furcus in having a distinct anus, but T. graminis second-stage juveniles (J2) do not have a bifid tail. T. semipenetrans does not have a perceptible anus. The mature female of T. graminis has a mucronate pointed terminus while T. semipenetrans has a smooth and round terminus. T. graminis males have wider stylet knobs and basal bulb and a longer tail than T. semipenetrans males. T. graminis J2 have a longer posterior body portion (without large fat globules) than T. semipenetrans J2. T. palustris resembles T. semipenetrans in having an undetectable anus but differs by the short and conoid mature female postvulval section. The male of T. palustris has larger stylet knobs and basal bulb than those of T. semipenetrans and a bluntly rounded tail terminus, which is tapered in T. semipenetrans. T. palustris differs from T. furcus and T. graminis in having an undetectable anus, by the conoid postvulval section of mature females, by the shorter and rounded tail of males, and the shorter J2 posterior body section without large fat globules. T. graminis and T. palustris are parasites of indigenous flora of Florida.
Andropogon virginicus; broomsedge; citrus; Florida; Fraxinus caroliniana; physiological race; pop ash; taxonomy; Tylenchulus furcus; Tylenchulus graminis; Tylenchulus palustris; Tylenchulus semipenetrans; scanning electron microscopy
Meloidogyne hapla reproduced and suppressed growth (P < 0.05) of susceptible Lahontan and Moapa alfalfa at 15, 20, and 25 C. At 30 C, resistant Nevada Syn XX lost resistance to M. hapla. M. hapla invaded and reproduced on Rhizobium meliloti nodules of Lahontan and Moapa, inducing giant cell formation and structural disorder of vascular bundles of nodules without disrupting bacteroids. At 15, 20, and 25 C a M. chitwoodi population from Utah reproduced on Lahontan, Moapa, and Nevada Syn XX alfalfa, suppressing growth (P < 0.05). Final densities of the Utah M. chitwoodi population were greater (P < 0.05) than those of Idaho and Washington State populations on Lahontan at 15 and 25 C and on Nevada Syn XX at 15 C, but were less consistent and smaller (P < 0.05) than those of M. hapla on Lahontan and Moapa at 20 and 25 C. Inconsistent reproduction of the Utah M. chitwoodi population on alfalfa suggests the possible existence of nematode strains revealed by variability in alfalfa resistance. No reproduction or inconsistent final nematode population densities with no damage were observed on Lahontan, Moapa, and Nevada Syn XX plants grown in soil infested with Idaho and Washington State M. chitwoodi populations.
Columbia root-knot nematode; northern root-knot nematode; Medicago sativa; Lahontan; Moapa; Nevada Syn XX; Rhizobium meliloti; histopathology; pathogenicity; reproduction; resistance; temperature
cell hypertrophy; Globodera pallida; cyst nematode; histopathology; Lycopersicon esculentum; tomato; root gall; syncytium
The morphology of a population of Sphaeronema rumicis Kir'yanova found on cottonwood in Utah is illustrated by light and scanning electron micrographs, as well as by drawings. This is the first report of males of S. rumicis, a species also not known previously to occur in North America. S. rumicis females on cottonwood in the United States were smaller than those found by Kir'yanova on sorrel in the USSR. Females and second-stage juveniles (J2) from the United States had slightly shorter stylets than did females and J2 from the USSR. Males were vermiform and had degenerate esophagi. On secondary cottonwood roots S. rumicis induces formation of a syncytium originating from proliferated pericyclic cells. Thick outer walls, wall protuberances, absence of cell wall ingrowths, dense cytoplasm, and hypertrophied nuclei were the main characteristics of syncytia observed in S. rumicis-infected cottonwood roots.
cottonwood; histopathology; host response; morphology; parasitic habit; Populus angustifolia; scanning electron microscope; semiendoparasitic nematode; Sphaeronema rumicis; syncytium
spiral nematode; Zea mays; feeding behavior; histopathology; host response
Postinfection development of Meloidogyne chitwoodi from second-stage juveniles (J2) to mature females and egg deposition on 'Nugaines' winter wheat required 105, 51, 36, and 21 days at 10, 15, 20, and 25 C. At 25 C, the J2 induced cavities and hyperplasia in the cortex and apical meristem of root tips with hypertrophy of cortical and apical meristem cell nuclei, 2 and 5 days after inoculation. Giant cells induced by late J2 were observed in the stele 10 days after inoculation. Clusters of egg-laying females were common on wheat root galls 25 days after inoculation. Juveniles penetrated wheat roots at 4 C and above, but not at 2 C, when inoculum was obtained from cultures grown at 20 C, but no penetration occurred at 4 C when inoculum was stored for 12 hours at 4 C before inoculation. In northern Utah, J2 penetrated Nugaines wheat roots in the field in mid-May, about 5 months after seedling emergence. M. chitwoodi eggs were first observed on wheat roots in mid-July when plants were in blossom. Only 40% of overwintered M. chitwoodi eggs hatched at 25 C.
Columbia root-knot nematode; Triticum aestivum; histopathology; life cycle; postinfection development; root infection; temperature
Columbia root-knot nematode; histopathology; host response; reproduction; orchardgrass; wild ryegrass; wheatgrasses
Heterodera schachtii, Meloidogyne hapla, and Nacobbus aberrans either alone, or in various combinations with each other, can, when inoculated at a concentration of 12 second-stage juveniles/ cm³ of soil, cause a significant (P = 0.01) suppression of growth of sugarbeet (cv. Tasco AH14) seedlings. M. hapla and H. schachtii decreased growth of sugarbeet more than N. aberrans over a 60-day period. The adverse effect of N. aberrans on the final population/initial population (Pf/Pi) ratio for either M. hapla or H. schachtii was dependent on time, and was more accentuated on that of M. hapla than on that of H. schachtii. Neither M. hapla nor H. schachtii had an adverse effect on the Pf/ Pi ratio of N. aberrans. N. aberrans is considered to be less aggressive on sugarbeet than either H. schachtii or M. hapla. Sections of sugarbeet roots infected simultaneously with H. schachtii and N. aberrans showed scattered vascular elements between the N. aberrans syncytium located in the central part of the root and that of H. schachtii in the peripheral position.
Beta vulgaris; false root-knot nematode; histopathology; northern root-knot nematode; Pf/Pi; sugarbeet cyst nematode; yield suppression