Jason D. Stanley

Identification and isozyme characterisation of Meloidogyne spp. infecting horticultural and agronomic crops, and weed plants in Florida.

A total of 327 root samples collected from horticultural and agronomic crops, and weeds associated with these crops in Florida crop production regions, were examined. Isozyme phenotypes, esterase (EST) and malate dehydrogenase (MDH) phenotypes were used to characterise and identify the species of Meloidogyne present in these samples. At least 26 females from each sample were examined using polyacrylamide gel electrophoresis. Sixteen major bands of EST activity were found, corresponding to 12 phenotypes. A species-specific EST phenotype was consistently associated with each of the Meloidogyne spp. identified: Meloidogyne arenaria, M. floridensis, M. graminicola, M. hapla, M. incognita, M. javanica, M. mayaguensis and M. partityla. Two unique EST phenotypes, which have not been described, were found associated with three unidentified nematode populations. Five bands of MDH activity and four phenotypes were also found among the populations. During this study, new host records were determined for M. floridensis and M. mayaguensis, two recently reported Meloidogyne spp. in Florida. Plant species found as new hosts of M. floridensis were Cucumis sativus, Phaseolus sp., Solanum melongena and one weed species, Emilia sonchifolia, and the M. incognita-resistant peach rootstock ‘Flordaguard’. New hosts for M. mayaguensis were Carica papaya, Capsicum annuum var. Longum, and six weed plants, including Eclipta prostrata, Fatoua villosa, Panicum sp., Poinsettia cyathophora, Solanum americanum and also one unidentified weed species belonging to the family Acanthaceae. To our knowledge, Florida is the only geographic area of North America where M. floridensis and M. mayaguensis have been detected.

Hemicaloosia vagisclera n. sp. (Nematoda: Caloosiidae) from Bermuda grass in Florida and its phylogenetic relationships with other criconematids

Hemicaloosia vagisclera n. sp. is described from Bermuda grass (Cynodon dactylon) in Florida. This new species is characterised by females with body slightly ventrally arcuate in death, face with a prominent elliptical oral disc, large amphids, slender stylet with mean length 64 μm, lateral field consisting of a single longitudinal line marked by continuous and discontinuous transverse striae, oval and full spermatheca, sclerotised vagina vera and tail annuli width greater than that of remaining body annuli. Diagnostic characters for the males are a C-shaped body, head with 4-5 faint lip annuli and pronounced oval oral disc, lateral field with two longitudinal lines intersected by transverse striae, tail digitate in the distal portion posterior to bursa, distinctly annulated and with a round terminus. Molecular characterisation of H. vagisclera n. sp. using the D2-D3 domain of 28S rRNA, partial 18S rRNA and ITS rRNA gene sequences is also provided. The phylogenetic relationships of this species with other representatives of the suborder Criconematina are presented and indicate that H. vagisclera n. sp. has sister relationships with Caloosia longicaudata supporting the classification of Caloosia together with Hemicaloosia as separate genera in the family Caloosiidae. A diagnostic PCR-ITS-RFLP profile for H. vagisclera n. sp. is also given together with an identification key for seven known species of Hemicaloosia.

Characterisation of a topotype and other populations of Hemicriconemoides strictathecatus Esser, 1960 (Nematoda: Criconematidae) from Florida with description of H. phoenicis sp. n. from the USA

Pablo Castillo and Juan E. Palomares-Rius acknowledge support from grant AGR-136 from ‘Consejeria de Economia, Innvovacion y Ciencia’ from Junta de Andalucia, and the European Social Fund and Sergei A. Subbotin acknowledges support from the Russian Foundation of Basic Research, project number 14-04-00953.

First Report of Laurel Oak as a Host for the Pecan Root-Knot Nematode, Meloidogyne partityla, in Florida

Roots of laurel oak (Quercus laurifolia Michx.), member of the family Fagaceae, were found to be heavily galled by the pecan root-knot nematode, Meloidogyne partityla, in two separate home gardens between 2010 and 2012, in Alachua Co., FL. Distinct round galls were observed on secondary and tertiary roots. Internally, root-knot nematode females were clearly visible when the roots were thinly sliced and egg masses were seen protruding from the root surfaces. The nematode species identification was performed using morphology of the male stylet, selected characters of the second-stage juveniles (J2), female perineal patterns, and esterase (EST) and malate dehydrogenase (Mdh) isozyme phenotypes. Morphology of perineal patterns of females, body, stylet, and tail length of the J2 and males all matched those of the original description of M. partityla (2). A swollen deeply grooved rectum was observed in the J2. The male stylet had a blunt tip with a prominent thickening at the junction between the cone and shaft. The stylet knobs of males and females were bipartite, each incised by a deep medium longitudinal groove (2). The isozyme phenotypes (EST = Mp3; Mdh = N1a) were consistent with those previously reported for M. partityla from Florida (1). Mitochondrial DNA (mtDNA) (3) and ribosomal internal transcriber spacer (ITS) DNA (4) of females were amplified to further confirm the nematode species identification. The mtDNA amplification using the C2F3/1108 primer set (3) and the ITS amplification using a recently available M. partityla specific primer set (4) produced fragments of approximately 530 bp and 550 bp, respectively. These were consistent with those already reported for this nematode species. This first report of a plant host for the pecan root-knot nematode outside of the family Juglandaceae indicates that the nematode may have migrated from Quercus species to pecan trees during the period when orchards were being established in Florida. To our knowledge, this is the first report of the pecan root-knot nematode infecting laurel oak. References: (1) J. A. Brito et al. Nematology 10:757, 2008. (2) Kleynhans, K. P. N. Phytophylatica 18:103, 1986. (3) T. O. Powers et al., J. Nematol. 37:226, 2005. (4) R. A. Stamler. M. S. thesis, New Mexico State University, Las Cruces, 2009.

Description of Tylenchulus musicola sp. n. (Nematoda: Tylenchulidae) from banana in Iran with molecular phylogeny and characterisation of species of Tylenchulus Cobb, 1913.

During a survey conducted on banana plantations in Sistan and Blouchestan province, south-east Iran, a new species of Tylenchulus was extracted from the soil and roots of banana plants. This species, named Tylenchulus musicola sp. n., is characterised by mature females having a swollen, hook-shaped body with a conical and elongate post-vulval portion ending in a round terminus, males having a weak stylet and a cylindrical and thick tail ending in a bluntly rounded and smooth terminus, and by second-stage juveniles having a slender body and a posterior body portion ending in a finely pointed or mucronate terminus. The results of glasshouse host tests indicated that the new species does not parasitise sugarcane ratoons or sour orange seedlings. Tylenchulus musicola sp. n. is distinguished from other known Tylenchulus species by the sequences of D2-D3 expansion segments of 28S rRNA and ITS rRNA genes. Phylogenetic relationships within Tylenchulus were reconstructed based on rRNA gene sequences using Bayesian inference. Diagnostic PCR-ITS-RFLP profiles are presented for T. musicola sp. n., T. furcus, T. graminis, T. palustris, T. semipenetrans and Trophotylenchulus floridensis. PCR with species-specific primers and genus-specific primer are tested and developed for rapid identification of five Tylenchulus species. An identification key to Tylenchulus species is provided.

Meloidoderita whittoni (Sledge & Christie, 1962) comb. n. (Tylenchida: Sphaeronematidae) and its parasitic habits on sweet gum ( Liquidambar styraciflua L.)

Morphological and molecular analyses of three populations of Meloidoderita whittoni (Sledge & Christie, 1962) comb. n. (syn. Sphaeronema whittoni ; Tumiota whittoni ) collected in Florida from sweet gum ( Liquidambar styraciflua L.) indicated that this species is a representative of Meloidoderita rather than Sphaeronema , where it was included in the original description, or Tumiota , to where it was subsequently transferred. However, this species can be considered an atypical representative of the genus, because it differs from the other species of this genus in having females retaining the eggs inside a thin-walled uterus, which remains encased inside their body. After egg deposition inside the uterus, the female dies and its body is transformed into a persistent tanned sac with a thick cuticle, devoid of ornamentations, which protects the eggs like a heteroderid cyst. The female secretes from the vulva a gelatinous matrix, which becomes hardened in time and encases its body for protection against predation and parasitism by biological antagonists as has been suggested for other tylenchuloid nematodes. No egg deposition outside the female body was observed. Second-stage juveniles of this species have a semi-endoparasitic, rather than endoparasitic, habit as in other known Meloidoderita species. This is the first report of a sphaeronematid having a cyst stage fitting the definition of a heteroderid cyst. Phylogenetic relationships between some species of Tylenchuloidea and Criconematina are analysed using the partial 18S rRNA, the D2-D3 of 28S rRNA and the ITS rRNA gene sequences.