New species of Rhabdochona Railliet, 1916 (Nemata: Rhabdochonidae) from Rainbow Trout in California Streams.

Three new species of Rhabdochona Railliet, 1916 are described and illustrated from Salmo gairdneri Richardson (rainbow trout) in freshwater streams in California: Rhabdochona californiemis n. sp., R. paxmani n. sp., and R. satmonis n. sp. Rhabdochona californiensis n. sp. is characterized by 14 anteriorly directed teeth in the prostome, egg devoid of filaments or floats, male and female tail terminus with a single mucro, left (long) spicule slender with a moderate distended podoid terminal end, spicular ratio 1:3.8. Rhabdochona paxmani n. sp. is characterized by 10 teeth in the prostome, eggs with polar floats, left (long) spicule slender with podoid terminus distended and having a minute subterminal spine; right spicule with prominent gorgeret (barb), spicular ratio 1:4.3, male and female tail terminus with a cuticular conical rounded short projection. Rhabdochona salmoni, n. sp. is characterized by 10 teeth anteriorly directed in the prostome, eggs with polar floats, left spicule slender with a distended podoid terminus; right spicule with a sharply indented gorgeret, spicular ratio 1:4.3, male and female tail terminus with a conical or rounded tip.

Vector Capability of Xiphinema americanum sensu lato in California.

Seven field populations of Xiphinema americanum sensu lato from California's major agronomic areas were tested for their ability to transmit two nepoviruses, including the prune brownline, peach yellow bud, and grapevine yellow vein strains of tomato ringspot virus and the bud blight strain of tobacco ringspot virus. Two field populations transmitted all isolates, one population transmitted all tomato ringspot virus isolates but failed to transmit bud blight strain of tobacco ringspot virus, and the remaining four populations failed to transmit any virus. Only one population, which transmitted all isolates, bad been associated with field spread of a nepovirus. As two California populations of Xiphinema americanum sensu lato were shown to have the ability to vector two different nepoviruses, a nematode taxonomy based on a parsimony of virus-vector relationship is not practical for these populations. Because two California populations of X. americanum were able to vector tobacco ringspot virus, commonly vectored by X. americanum in the eastern United States, these western populations cannot be differentiated from eastern populations by vector capability tests using tobacco ringspot virus.

Hirschmanniella pomponiensis n. sp. (Nemata: Pratylenchidae), Parasitic on Bulrush, Scirpus robustus Pursh.

A new species of Hirschmanniella was found in bulrush roots; LM and SEM morphological studies revealed that it is distinct from other species in the genus. Therefore, it is designated Hirschmanniella pomponiensis n. sp. Six lips are fused to form a hexagonal labial plate, six inner sensilla encircle the stoma opening, and four cephalic sensilla open in the corners of subdorsal and subventral lips. Cephalic lip region consists of six or seven annuli. The female has incomplete areolation in the lateral field, the intestine overlaps the rectum, the tail tip is pointed and without annulation.

Morphometric Analysis of Anguina amsinckiae from Three Host Species.

Amsinckia species (fiddleneck) in the South Coast Ranges of California were surveyed to determine if any of the 12 different California species of Amsinckia are hosts of the nematode, Anguina amsinckiae (Steiner and Scott, 1935) Thorne, 1961. Previously only Amsinckia intermedia Fischer and Meyer was reported as a host of Anguina amsinckiae. The survey established that there are at least two additional hosts of Anguina amsinckiae: Amsinckia lycopsoides Lehmann and Amsinckia gloriosa Suksdorf. Seven sites containing nematode-infected Amsinckia plants were discovered. Every site contained two or more species of Amsinckia; however, only one site contained more than one species of Amsinckia that was galled. Nematode specimens from A. intermedia, A. lycopsoides, and A. gloriosa were used in a morphometric analysis of 14 morphological variables. Stepwise discriminant analysis of the variables to separate the populations by host were successful for females, and the pairwise F-tests showed all three populations to have different group means (P < 0.05). Males from the three hosts were not always separable, however, as only the nematodes from Amsinckia gloriosa had a different group mean (P < 0.05).

Meloidogyne californiensis n. sp. (Nemata: Meloidogyninae), Parasitic On Bulrush, Scirpus robustus Pursh.

Meloidogyne californiensis n. sp. is described and illustrated from bulrush Scirpus robustus in California. LM and SEM studies revealed that this species differs from other known species in the genus Meloidogyne especially by the prominent posterior cuticular protuberances in the female, the distinct shape of the perineal pattern which is marked by one prominent stria in the perineum, indistinct lateral lines, many broken discontinuous striae on both sides of the arch, and the excretory pore being located posterior to stylet base. Second-stage juveniles 448-628 mum long, stylet length 11-13 mum, styler delicate, with small knobs sloping posteriorly, cephalic region with 2 or 3 annuli, and inflated rectum. Males vary greatly in size (712-1,952 mum), stylet length 18-28 mum (mean 22 mum), cephalic region slightly set off the body with two or three annuli, spear heavy with massive rounded knobs, lateral field marked by four areolated incisures as seen by SEM.

A New Gall-Forming Species of Anguina Scopoli, 1777 (Nemata: Anguinidae) on Bluegrass, Poa annua L., from the Coast of California.

Anguina pacificae n. sp. is described and illustrated from stem galls on bluegrass, Poa annua L., from golf courses along coastal California. The females are characterized by constrictions in the anterior and posterior connections of the isthmus with the respective parts of the esophagus, the long multicellular columella, and the sharply pointed tail tip. Males are dorsally curved after death; body width is increased markedly after 13 annuli in both sexes, and the tail is conical and with an acute terminus.

Postembryonic Development of the Redwood Nematode, Rhizonema sequoiae (Nemata: Heteroderidae).

Second-stage larvae of Rhizonema sequoiae Cid del Prado Vera et al. developed into adult females in 6 months or adult males in 3 - 4 months on roots of Sequoia sempervirens maintained in a growth chamber at 16 C with a 12-hour light period. Under these conditions the second-stage larvae increased in diameter, the central cells of the genital primordium increased in size, and their nuclei enlarged. Mesenchymal cells accumulated in the esophageal and tail regions. Second-stage larvae become third-stage males or females 2 months after inoculation of redwood roots. Their sex could be distinguished by the ratio of length to width of the genital primordium, 3.4 for males and 1.6 for females. The stylet in both sexes became slender, the median bulb became robust and almost spherical, and rings of punctation on the cuticle were evident. Fourth-stage females developed in 3 months from the time of inoculation, and fourth-stage males in slightly less time. At this stage the females were more swollen than the males, the rectum was conspicuous, their reproductive system was in the process of elongation, and the annulation of the cuticle was more evident. The ratio of males to females was 2.3. Mature females were completely inside the roots and did not form cysts. The cuticle was entirely annulated, and the first eggs were detected inside the female 4 months after inoculation and started the production of abundant gelatin-like material. The new generation of second-stage larvae hatched inside the female 2 months after she matured, completing the life cycle in 8 months. The redwood nematode also completed its life cycle in 8 months under greenhouse conditions, but the ratio of males to females increased to 7.4. The entire nematode population died out at 25 C after 6 months. In a Marin County, California, forest, where this nematode occurs naturally, the temperature averaged only 9 C over the November to June period of this study, and the redwood nematode reached the fourth stage with a male-to-female ratio of 1.8.

Rhizonema sequoiae n.gen. n.sp. from Coast Redwood Sequoia sempervirens (D.Don) Endl.

Rhizonema sequoiae n.gen, u. sp. is described from the roots of Coast Redwood, Sequoia sempervirens (D. Don) Endl., growing near Lake Lagunitas, Marin County, California. Rhizonema females are annulated over their entire bodies, are wholly embedded in host tissue, and secrete an abundant amount of gel material. Mature females do not form a cyst. The vulva is located on a large posterior terminal cone, and the anus is on the dorsal vulval lip. Esophageal glands of the second-stage larvae fill more than half of the body cavity. Tails of the vermiform males are blunt, and a cloacal tubus is present.

"Blinding" of shoots and a leaf gall in Amsinckia intermedia induced by Anguina amsinckia (Steiner and Scott, 1934) (Nemata, Tylenchidae), with a note on the absence of a rachis in A. amsinckia.

"Blinding" and a leaf gall induced on Amsinckia intermedia Fisch. and Mey. by Anguina amsinckia (Steiner and Scott) are described. A. amsinckia induced blinding by galling the terminal apical meristem of its host. The leaf gall was formed by a ventral curling of the distal edge of the leaf. The absence of a rachis in the ovary of A. amsinckia is noted.

The role of cuticular strata nomenclature in the systematics of nemata.

A system of cuticular nomenclature based on the strata observed in Enoplia is proposed. Nematode cuticle is divided into four fundamental strata: epicuticle, exocuticle, mesocuticle, and endocuticle. Application of this system allows the correlation of complementary strata throughout Nemata. The major taxonomic categories within Nemata are differentiated on the basis of their cuticular strata as compared with the Enoplia model cuticle.

Nematicidal injection: targeted control of plant-parasitic nematodes of trees and vines.

Pressurized injection of nematicidal solutions was effective for control of nematodes within trees and vines. Significant (P = 0.01) control of Pratylenchus vulnus on grape was attained with four nonfumigants (carbofuran, oxamyl, phenamiphos, and sulfocarb) and one fumigant nematicide (DBCP). Pratylenchus penetrans was controlled (P = 0.05 and 0.1) in apples and walnuts with sulfocarh and oxamyl. This species also was controlled in apples with carbofuran and phenamiphos. The advantages of pressure injection over traditional methods of nematicide applications are discussed.

Location of Grapevine Fardeaf and Yellow Mosaic Virus Particles in Xiphinema index.

Particles of fanleaf and yellow mosaic viruses are reported in the lumen of the esophagus of Xiphinerna index. Differences in cuticular morphology suggest differences in charged receptor sites which may offer an explanation for virus location and orderly arrangement.

The Effects of Soil Salinity and Meloidogyne javanica on Tomato.

A non-sodic, non-saline sandy loam soil was salinized to anion-cation ratios similar to those naturally occurring in Iraq and California. The interactions of saline soils (conductivities 4, 8, 12 and 16 mmhos/cm) with a moderately salt-tolerant plant (Lycopersicon esculentum 'Marimond') and a plant parasitic nematode (Meloidogyne javanica) were investigated. Plant parasitic nematodes were shown to be an important modifying influence within the plant environment, either accentuating or ameliorating salinity stress effects.

Axenic Ovarial Explants from the Marine Nematode Deontostoma californicum on Culture Media.

The gonads of Deontostoma californicum were isolated from the organismal environment by dissection. In an attempt to approximate the in vivo condition and to maintain in vitro architecture and function ten media recommended for the culture of insect cells or organs were tested. The media were prepared in two series: one according to published recommendations and the second substituting filtered seawater for the inorganic salts and distilled water. Media were prepared as both liquid and gel (agar) with and without antibiotics. Whole animals and eggs were placed on the same culture media series as the ovarial explants. Ovarial explant reaction was divided into those which supported the entire gonad and those which supported the ovary or ova-containing oviduct. Seawater preparations of Samia and Grace culture media were outstanding for support of the entire explant. Eggs underwent their greatest development in seawater without antibiotics. Prolonged survival of whole animals took place only in those media (A-l, C-G, 26c, 199, Mosquito, and Media B) in which the inorganic salts and distilled water were replaced by filtered seawater. The results demonstrated that those conditions suitable for adults on culture media are not necessarily suitable for eggs, larvae, or tissue explants.