The Genera of the Subfamily Heteroderinae (Nematoda: Tylenchoidea) with a Description of Two New Genera

The family Heteroderidae, its two subfamilies Heteroderinae and Meloidogyninae and the nominal genera of Heteroderinae (Heterodera Schmidt, 1871; Meloidodera Chitwood, Hannon &Esser, 1956; and Cryphodera Colbran, 1966) are rediagnosed. Meloidoderita Pogosyan, 1966 is considered a genus inquirenda. Two new genera from southern California are described in the subfamily Heteroderinae. A key to the genera, illustrations and a phylogeny of the Heteroderinae are proposed.     

Fine Structure of Body Wall Cuticle of Females of Eight Genera of Heteroderidae

Body wall cuticle of adult females of eight genera within the Heteroderidae was examined by transmission electron microscopy for comparison with previously studied species within the family. Cuticle structure was used to test some current hypotheses of phylogeny of Heteroderidae and to evaluate intrageneric variability in cuticle layering. Verutus, Rhizonema, and Meloidodera possess striated cuticle surfaces and have the simplest layering, suggesting that striations have not necessarily arisen repeatedly in Heteroderidae through convergent or parallel evolution. Atalodera and Thecavermiculatus possess similar cuticles with derived characteristics, strengthening the hypothesis that the two genera are sister groups. Similarly, the cuticle of Cactodera resembles the specialized cuticle of Globodera and Punctodera in having a basal layer (D) and a surface layer infused with electron-dense substance. Heterodera betulae has a unique cuticle in which the thickest layer (C) is infiltrated with an electron-dense matrix. Little intrageneric difference was found between cuticles of two species of Meloidodera or between two species of Atalodera. However, Atalodera ucri has a basal layer (E) not found in other Heteroderidae. The most striking intrageneric variation in cuticle structure was observed between the thin three-layered cuticle of Sarisodera africana and the much thicker four-layered cuticle of Sarisodera hydrophila; results do not support monophyly of Sarisodera.     

An Illustrated Key to the Cyst-Forming Genera and Species of Heteroderidae in the Western Hemisphere with Species Morphometrics and Distribution

Diagnoses of the cyst-forming genera of Heteroderidae (viz., Heterodera, Sarisodera, Globodera, Punctodera, Cactodera, and Dolichodera) and distribution and morphometrics of the 34 known cyst species in the Western Hemisphere are presented along with an illustrated key for the identification of these genera and species. The key is based mainly on cysts and larvae, and important morphological and diagnostic features are extensively shown by LM and SEM illustrations. The genus Bidera is placed as a new synonym under the genus Heterodera.     

Cladistic Approaches in the Study of Soil and Plant Parasitic Nematodes

Cladistic analysis of free-living soil nematodes of the Leptonchoidea(Nematoda: Dorylaimida) resulted in groupings different fromthose obtained by traditional methods. We can interpret distributionsof species groups obtained by phyletic analysis in relationto plate tectonic events. Similar techniques are applicableto plant parasitic nematodes. Grouping on the basis of synapomorphiesproduced a cladogram of genera of the family Heteroderidae (Nematoda:Tylenchida) in which Meloidodera and Cryphodera appear to bethe most ancestral genera and the cyst forming genera the mostderived. A cladogram of groups of species in Heterodera sensulato showed a major division, with the round cyst nematodesand the Cacli group in one grouping and the rest of the Heteroderaspecies in the second. I interpret present-day distributionsby a strict vicariance view and suggest potential falsifiers;and also discuss ancient dispersal routes as alternative waysof thinking about nematode distribution.     

Comparative detailed morphology of the Heteroderinae Filip'ev & Schuurmans Stekhoven, 1941, sensu Luc et al. (1988): phylogenetic systematics and revised classification

Taxonomic schemes for the Heteroderinae Filip'ev & Schuurmans Stekhoven, 1941, sensu Luc et al., (1988) have been unstable due to the large number of genera and the paucity of known reliable characters. Reliable characters are essential when using phylogenetic inference in developing a natural classification. Morphological and developmental studies using light, scanning and transmission electron microscopy have revealed the new characters of host response, en face patterns, phasmid structure and female cuticular layers. These techniques also gave us insight into the homoplasy and polarity of many characters, revealed previously undetected character states and clarified misinterpreted character states. A matrix with the 19 most reliable characters is proposed for 20 operational taxonomic units (OTUs) and we employ this matrix for comparing computer generated phylogenetic analyses of the PHYLIP and PAUP packages. PAUP was deemed the more reliable parsimony algorithm for phylogenetic analysis of the Heteroderinae (Fink, 1986; Platnick, 1987). Monophyly of Atalodera + Sherodera + Thecavermiculatus (tribe Ataloderini), and Cactodera + Heterodera + Afenestrata, as well as Punctodera + Globodera + Dolichodera is supported by both programs. Most importantly, analyses strongly support monophyly of all cyst-forming genera (tribe Heteroderini) contrary to previous hypotheses of repeated evolution of the cyst (Wouts, 1985). In addition, monophyly of the Heteroderini with the Ataloderini is demonstrated. PAUP indicates monophyly of Sarisodera + Rhizonema + Bellodera + Hylonema and Ekphymatodera (tribe Sarisoderini new rank). Monophyly of the Sarisoderini was at first only weakly supported, but, subsequently, the reduced width of the submedial lips of second stage juveniles and males was recognized as a synapomorphy which strengthened subsequent PAUP trees and monophyly of the tribe. The present study rejects as paraphyletic or polyphyletic several previously proposed combinations, including Thecavermiculatus sequoiae (versus Rhizonema sequoiae), Sarisodera africana (versus Afenestrata africana), Dolichodera andinus (versus Thecavermiculatus andinus). The question whether T. andinus is a distinct genus, was not resolved due to insufficient data. PAUP supports our previous observations that Cactodera betulae is intermediate in a transformation series between other Cactodera and Heterodera: it also indicates these species as bring monophyletic with Heterodera + Afenestrata, but not with other Cactodera. Although these phylogenetic analyses strongly support some relationships, they indicate unresolved alternative hypotheses for others. Meloidodera (tribe Meloidoderini) and Cryphodera (tribe Cryphoderini) must be investigated for consideration of a possible synapomorphy not included in the present data matrix. Future studies are proposed to more clearly define the monophyly of the Heteroderini, as well as the Sarisoderini. Tests are also proposed to clarify questions of the monophyly of Verutus (tribe Verutini new rank) with the Heteroderinae versus other Tylenchida.     

Phylogenetic relationships within the cyst-forming nematodes (Nematoda, Heteroderidae) based on analysis of sequences from the ITS regions of ribosomal DNA

The ITS1, ITS2, and 5.8S gene sequences of nuclear ribosomal DNA from 40 taxa of the family Heteroderidae (including the genera Afenestrata, Cactodera, Heterodera, Globodera, Punctodera, Meloidodera, Cryphodera, and Thecavermiculatus) were sequenced and analyzed. The ITS regions displayed high levels of sequence divergence within Heteroderinae and compared to outgroup taxa. Unlike recent findings in root knot nematodes, ITS sequence polymorphism does not appear to complicate phylogenetic analysis of cyst nematodes. Phylogenetic analyses with maximum-parsimony, minimum-evolution, and maximum-likelihood methods were performed with a range of computer alignments, including elision and culled alignments. All multiple alignments and phylogenetic methods yielded similar basic structure for phylogenetic relationships of Heteroderidae. The cyst-forming nematodes are represented by six main clades corresponding to morphological characters and host specialization, with certain clades assuming different positions depending on alignment procedure and/or method of phylogenetic inference. Hypotheses of monophyly of Punctoderinae and Heteroderinae are, respectively, strongly and moderately supported by the ITS data across most alignments. Close relationships were revealed between the Avenae and the Sacchari groups and between the Humuli group and the species H. salixophila within Heteroderinae. The Goettingiana group occupies a basal position within this subfamily. The validity of the genera Afenestrata and Bidera was tested and is discussed based on molecular data. We conclude that ITS sequence data are appropriate for studies of relationships within the different species groups and less so for recovery of more ancient speciations within Heteroderidae.     

Heterodera graminophila n. sp. (Nematoda Heteroderae) from Grass with a Key to Closely Related Species

Heterodera graminophila n. sp., a member of the H. goettingiana group, is described and illustrated from roots of barnyard grass, Echinochloa colonum (L.) Link, in Baton Rouge, La. This new abullate species, having second-stage larvae with only three lines in the lateral field, is most closely related to H. cyperi Golden, Rau &Cobb, 1962, and H. graminis Stynes, 1971, but differs particularly in having a small, inconspicuous anus without a circum-anal pattern and located about 20% of the cyst length from the vulval cone terminus, and a longer vulval slit averaging 45 μ in length. A key, based on cyst and larval characters, is presented for identification of the 10 Heterodera species in the H. goettingiana group.     

A Key and Compendium to Species of the Heterodera avenae Group (Nematoda: Heteroderidae)

A key based on cyst and juvenile characters is given for identification of 12 valid Heterodera species in the H. avenae group. A compendium providing the most important diagnostic characters for use in identification of species is included as a supplement to the key. Cyst characters are most useful for separating species; these include shape, color, cyst wall pattern, fenestration, vulval slit length, and the posterior cone including presence or absence of bullae and underbridge. Also useful are those of second-stage juvenile characteristics including aspects of the stylet knobs, tail hyaline tail terminus, and lateral field. Photomicrographs of diagnostically important morphological features complement the compendium.     

Relative DNA Content and Chromosomal Relationships of some Meloidogyne, Heterodera, and Meloidodera spp. (Nematoda: Heteroderidae)

The relative DNA content of hypodermal nuclei of preparasitic, 2nd-stage larvae was determined cytophotometrically in 19 populations belonging to 13 species of Meloidogyne, Heterodera and Meloidodera. In Meloidogyne hapla, M. arenaria, M. incognita and M. javanica, total DNA content per nucleus is proportional to their chromosome number, indicating that chromosomal forms with high chromosome numbers are truly polyploid. M. graminicola, M. grarninis and M. ottersoni have a DNA content per chromosome significantly lower than that of the other Meloidogyne species. Within Heterodera, species with high chromosome numbers have proportionally higher DNA content, indicating again polyploidy. DNA content per chromosome in Meloidogyne is one third that of Heterodera and one haft that of Meloidodera floridensis. The karyotypic relationships of the three genera are still not clearly understood.     

Morphological and morphometrical analysis of Heterodera spp. populations in Jordan

Phenotypic diversity of five Jordanian populations of cyst nematodes, Heterodera spp. collected from five regions from Jordan (Ar-Ramtha, Madaba, Dana, Al-Karak, and Jerash) was investigated. Soil samples were collected from one representative field in each region. Morphological and morphometrical characteristics revealed that Heterodera latipons is dominated in cereal fields at Ar-Ramtha, Madaba, Dana and Al-Karak regions and Heterodera schachtii in Jerash. Cysts populations from all cereal fields had bifenestrate vulval cone and a strong underbridge. Wherever, cysts of the cabbage population had ambifenestrate vulval cone with long vulval slit. The bullae were absent in Ar-Ramtha, Madaba and Dana populations, but present in Al-Karak and Jerash. Based on 12 morphometrical characters, the first three functions in canonical discriminant analysis accounted 99.3% of the total variation. Distance from dorsal gland duct opening to stylet base, underbridge length, a = L/W (body length/midbody width) and length of hyaline tail tip had strong and significant contributions in the first function. While the second function was strongly influenced by length of hyaline tail, fenestral length, fenestral width and tail length. However, the third canonical discriminate function was found to be influenced by stylet length, fenestral length, a = L/W (body length/midbody width) and underbridge width. The graphical representation of the distribution of the samples showed that the first canonical discriminant function clearly separated H. schachtii from Jerash from other populations. Whereas, H. latipons collected from Madaba and Dana were clearly separated in the second function. The results indicated that differences at morphological and morphometrical levels revealed diverse populations of Heterodera spp. in Jordan.     

Fine Structure of Sperm of Ekphymatodera thomasoni (Heteroderinae,Nemata)

Fine structure of developing sperm of the monospecific genus, Ekphymatodera, was compared with other Heteroderinae as part of a study to recognize diversity and phylogenetically informative characters within the subfamily. Sperm of Ekphymatodera originate from germ cells connected to a central rachis, a character which is shared with Globodera, but not with other Heteoderinae. In Ekphymatodera, and cyst-forming genera, a layer of cortical microtubules lies just beneath the surface of the plasma membrane. Sperm of Ekphymatodera are unique among Heteroderinae examined by the presence of spiral surface elevations on the filopodia, a character that may prove to be a synapomorphy for Sarisoderini. Fibrous bodies are abundant in spermatids; however, they do not persist in sperm of Ekphymatodera as they do in Meloidodera and Verutus. The male gonad of Ekphymatodera is lined by epithelial cells, which are greatly enlarged near the ejaculatory canal. These enlarged cells contain vesicles with concentric lamellar inclusions, not observed in other genera of the subfamily. Sperm of Heteroderinae are rich in diversity, and examination of additional representative species may indicate new phylogenetically informative characters.     

Heterodera betulae n. sp. (Heteroderidae), a Cyst-forming Nematode from River Birch

A new species of the genus Heterodera A. Schmidt, 1871 parasitic on river birch, Betula nigra L., is described and illustrated. Females and cysts are lemon-shaped to almost spherical with slight vulval protrusion. Female cuticles have a thick subcrystalline layer. The average cyst size is 763 by 616 [mu]. They are circumfenestrate with small anal opening and lack a yellow phase. The cyst wall pattern is typically network-like. All eggs are retained in the cyst, although a well-developed matrix is formed. The egg shell is without markings. The second-stage larvae average 462 [mu] in length and have 3 incisures in the lateral field. The tail terminal is shorter than the stylet. Males are rare. They have 4 incisures in the lateral field and bifid spicules. The relationship of H. betulae n. sp. to other Heterodera species is obscure.     

The taxonomy of Tylenchorhynchinae (Nematoda: Tylenchida) with longitudinal lines and ridges

Summary The taxonomy of those Tylenchorynchinae which have longitudinal lines or ridges on the cuticle is discussed. Dolichorhynchus is restricted to species with four incisures in the lateral field, lateral vulval flaps and a terminally notched bursa. D. prophasmis n. sp. is described. Neodolichorhynchus n. g. is erected for those species previously in Dolichorhynchus which have no lateral vulval flaps and a normal bursa, including: N. microphasmis (Loof, 1959) n.comb., N. judithae (Andrássy, 1962) n.comb., N. sulcatus (de Guiran, 1967) n.comb., and N. gladiolatus (Fortuner & Amougou, 1973) n.comb. Tessellus n.g. is proposed for T. claytoni (Steiner, 1937) n.comb. and T. pachys (Thorne & Malek, 1968) n.comb. the only remaining Tylenchorhynchus species with longitudinal cuticular lines. They are characterized by a rounded non-offset lip region, four incisures in the lateral field and a cuticular annulation divided into prominent blocks by deep longitudinal cuticular lines.     

Effect of Age on Body Wall Cuticle Morphology of Heterodera schachtii Schmidt females

Fine structure of the body wall cuticle of Heterodera schachtii is compared with respect to age and body region of the female. The cuticle is more complex than previously reported. In newly molted females only layers A, B, and C are present, but 4 weeks after the final molt a thin D layer is present between the midbody and base of the cone. This D layer is absent in the cone of H. schachtii, regardless of age. As females age, an additional layer E is produced and includes zones E₁ and E₂. Zone El apparently is unique to H. schachtii, whereas E₂ is likely to be homologous with a similar layer in Atalodera. In the cone of old females (ca. 8 weeks after the final molt) of H. schachtii, the two zones become irregular in shape and comprise bullae. The presence of a thin D layer in Heterodera strengthens the previous hypothesis of a single ancestor of cyst nematodes.     

The morphology of the upper lip of Cypridoidea ostracods: taxonomic and phylogenetic significance

This paper represents the first study of the morphology of the upper lip (labrum) and hypostome of ostracods using scanning electron microscopy (S.E.M.). There is considerable variation in the upper lip morphology of the 23 species of Cypridoidea (Podocopina) ostracods used in this study. The detail of the upper lip morphology of each species is very distinctive, so that species determination can be made on this feature alone, but it is not useful in diagnosing genera or subfamilies. The hypostome is not readily studied due to the large amounts of dense pseudochaetae (small, setae-like projections) protruding from it and hence is considered not to be a useful taxonomic feature. Several features of the upper lip and mouth region are documented for the first time. Comparisons of the general morphology of the upper lips of Recent ostracods with the upper lip of the fossil ostracod Pattersoncypris micropapillosa Bate, 1972, indicate that there has been very conservative evolution in these features since the Cretaceous.     

Molecular phylogeny of Pamphagidae (Acridoidea,Orthoptera) from China based on mitochondrial cytochrome oxidase II sequences

Abstract Phylogenetic relationships of Pamphagidae were examined using cytochrome oxidase subunit II (COII) mtDNA sequences (684 bp). Twenty‐seven species of Acridoidea from 20 genera were sequenced to obtain mtDNA data, along with four species from the GenBank nucleotide database. The purpose of this study was analyzing the phylogenetic relationships among subfamilies within Pamphagidae and interpreting the phylogenetic position of this family within the Acridoidea superfamily. Phylogenetic trees were reconstructed using neighbor‐joining (NJ), maximum parsimony (MP) and Bayesian inference (BI) methods. The 684 bp analyzed fragment included 126 parsimony informative sites. Sequences diverged 1.0%–11.1% between genera within subfamilies, and 8.8%–12.3% between subfamilies. Amino acid sequence diverged 0–6.1% between genera within subfamilies, and 0.4%–7.5% between subfamilies. Our phylogenetic trees revealed the monophyly of Pamphagidae and three distinct major groups within this family. Moreover, several well supported and stable clades were found in Pamphagidae. The global clustering results were similar to that obtained through classical morphological classification: Prionotropisinae, Thrinchinae and Pamphaginae were monophyletic groups. However, the current genus Filchnerella (Prionotropisinae) was not a monophyletic group and the genus Asiotmethis (Prionotropisinae) was a sister group of the genus Thrinchus (Thrinchinae). Further molecular and morphological studies are required to clarify the phylogenetic relationships of the genera Filchnerella and Asiotmethis.     

Finite element modeling of arachnid slit sensilla—I. The mechanical significance of different slit arrays

Arachnid strain sensitive slit sensilla are elongated openings in the cuticle with aspect ratios (slit length l / slit width b) of up to 100. Planar Finite Element (FE) models are used to calculate the relative slit face displacements, D _c, at the centers of single slits and of arrangements of mechanically interacting slits under uni-axial compressive far-field loads. Our main objective is to quantitatively study the role of the following geometrical parameters in stimulus transformation: aspect ratio, slit shape, geometry of the slits‘ centerlines, load direction, lateral distance S, longitudinal shift λ, and difference in slit length Δl between neighboring slits. Slit face displacements are primarily sensitive to slit length and load direction but little affected by aspect ratios between 20 and 100. In stacks of five parallel slits at lateral distances typical of lyriform organs (S = 0.03 l) the longitudinal shift λ substantially influences slit compression. A change of λ from 0 to 0.85 l causes changes of up to 420% in D _c. Even minor morphological variations in the arrangements can substantially influence the stimulus transformation. The site of transduction in real slit sensilla does not always coincide with the position of maximum slit compression predicted by simplified models. An erratum to this article can be found at