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  • Author or Editor: Louwrens R. Tiedt x
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Abstract

Criconema zantene n. sp., found in the rhizosphere of a Podocarpus sp. tree, is described and illustrated. Females are characterised by having 46-56 body annuli covered with tile-like scales, stylet 101-122 μm long, one lip annulus with a greater diameter than first body annulus, distinct submedian lobes, tooth-like lobes on posterior body annuli with a double row of lobes on first annulus directly posterior to vulva, a sigmoid vagina and an overhanging anterior vulval lip. Second, third and fourth stage juveniles with varying numbers of longitudinal rows of filamented scales on cuticle. Criconema princeps (Andrássy, 1962) Raski & Luc, 1985, Mesocriconema dherdei (De Grisse, 1967) Loof & De Grisse, 1989 and Paratylenchus straeleni (De Coninck, 1931) Oostenbrink, 1960 are reported from South Africa for the first time. These species are briefly discussed, illustrated and morphometrics given. Additional data is given for C. pauciannulatum Van den Berg, 1992.

In: Nematology

Abstract

Caloosia longicaudata is described from Maui, the Hawaiian Islands, for the first time and both sexes are characterised morphologically using light and scanning electron microscopy. Molecular characterisation of C. longicaudata 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 discussed. A diagnostic PCR-ITS-RFLP profile for C. longicaudata is given together with an identification table for eight species of Caloosia. Caloosia langola n. comb. is transferred to the genus and C. shorai is synonymised with H. psidii.

In: Nematology

Steinernema nguyeni n. sp. was recovered by baiting from beneath an Olea africana tree in South Africa. The combination of morphological and molecular features suggests that S. nguyeni n. sp. is a member of the feltiae-kraussei-oregonense group, clustering with members of this group in Clade III. The new species is morphologically characterised by the infective juvenile body length of 737 (673-796) μm and the number of ridges in the infective juvenile lateral field is 2, 8, 2. The male of the first generation can be recognised by the spicule length of 66 (58-75) μm and a gubernaculum length of 43 (30-55) μm. The first generation female can be recognised by the vulval lips only slightly protruding and the presence of low, double-flapped epiptygmata. Analysis of the ITS and D2-D3 regions of the ribosomal DNA confirms that S. nguyeni n. sp. differs from all other known Steinernema species.

In: Nematology

A new cyst nematode, herein described as Globodera capensis n. sp., was found on several farms in the Swartland and Sandveld areas in South Africa. As the host plant of G. capensis n. sp. is currently unknown, the species is represented by cysts and second-stage juveniles (J2) only. The cysts have a spherical form, are yellow to dark brown in colour and have bullae (vulval bodies) and subcuticular punctations. Six to 20 cuticular ridges/lines are present between the anus and vulval basin, Granek’s ratio is 0.7-4.0, the vulval basin diam. is 16-28.5 μm and vulval basin to anus distance is 19-60 μm. The J2 is 430-528 μm long and the stylet is 23-28 μm long with anteriorly flattened to rounded stylet knobs. These stages are morphologically and morphometrically very near to, or indistinguishable from PCN, G. artemisiae, G. millefolii and G. tabacum tabacum. It can be distinguished by the molecular characteristics of the ITS-region of the ribosomal DNA. Pairwise distances between closely related Globodera species show that G. capensis n. sp. differs the least in number of base differences per sequence from G. millefolii (63-64 bp) and most from an undescribed Globodera from Chile (72-73 bp). Phylogenetic relationships of G. capensis n. sp. with selected species of Punctoderinae, inferred from ITS-rRNA sequences by using the Maximum Likelihood method, indicate that G. capensis n. sp. occupies a basal position within a lineage of Globodera species from Europe, Asia and New Zealand that parasitises non-solanaceous plants. For diagnostic purposes, digestion of the ITS1 with AluI will distinguish G. capensis n. sp. from G. mexicana, G. pallida, G. rostochiensis and G. tabacum, but not from G. artemisiae, G. millefolii and G. zelandica, whilst FauI will distinguish G. capensis n. sp. from all the other Globodera species tested.

In: Nematology

Summary

Calcaridorylaimus heynsi n. sp. is the second species of the genus to be described by both morphological and molecular techniques. Morphologically, it can be distinguished from all known species of Calcaridorylaimus by a combination of the following characters: presence of advulval ornamentations, short body (0.90-1.33 mm), slightly anteriorly positioned vulva (V = 47.6 (45.8-49.8)), short odontostyle in females and males (13.1 (11.5-14.5) μm and 13.5 (12.0-18.0) μm, respectively), number of supplements (2 + 9-11), short spicules when measured along the median line (40.4 (38-42) μm) and pore-like vulval opening. It is closest to C. sirgeli, especially in the presence of advulval ornamentations and the pore-like vulva. Phylogenetic analysis based on partial D2-D3 segment of 28S rDNA sequences showed that C. heynsi n. sp. is in a well-supported sister relation with Mesodorylaimus sp. in a clade with C. cignatus and Mesodorylaimus spp. In the Bayesian tree, using partial sequences 18S rDNA, M. japonicus was the closest taxon to the new species.

In: Nematology

Pin nematodes of the genus Paratylenchus are widely distributed across the world and associated with many plant species. Morphological identification of Paratylenchus species is a difficult task because it relies on many characters with a wide range of intraspecific variation. In this study we provide morphological and molecular characterisation of several pin nematodes: Paratylenchus aquaticus, P. dianthus, P. hamatus, P. nanus and P. straeleni, collected in different states of the USA and South Africa. Paratylenchus aquaticus is reported from South Africa and Hawaii and P. nanus is found from South Africa for the first time. Morphological descriptions, morphometrics, light and scanning electron microscopic photos and drawings are given for these species. Molecular characterisation of nematodes using the D2-D3 of 28S rRNA and ITS rRNA gene sequence revealed that samples morphologically identified as P. aquaticus, P. hamatus and P. nanus indeed represent species complexes containing several species. Sequences of the rRNA genes are also provided for several unidentified Paratylenchus. Phylogenetic relationships within the genus Paratylenchus are given as inferred from the analyses of the D2-D3 of 28S rRNA and ITS rRNA gene sequences. We present here the most complete phylogenetic analysis of the genus.

In: Nematology

A new species of entomopathogenic nematode, Steinernema sacchari n. sp., was isolated by trapping with the sugar cane borer, Eldana saccharina, from soil of a sugar cane field in the KwaZulu-Natal province of South Africa. The new species is morphologically characterised by the length of the infective juvenile (IJ) of 680 (630-722) μm, tail length of 64 (51-74) μm, ratio a = 19 (14-23), H% = 49 (43-57) and E% = 82 (70-109). The pattern of the lateral field of the IJ of the new species is 2, 5, 2 ridges (3, 6, 3 lines or incisures). The male of the first generation can be recognised by the long spicule of 83 (73-89) μm, gubernaculum of 61 (50-68) μm, D% = 67 (54-88) and GS% = 73 (66-81). The first generation male lacks a mucron, while the second generation male always has one. The first generation female can be recognised by the vulval lips not being raised, the possession of long double-flapped epiptygmata and the lack of a postanal swelling. Analysis of the ITS and D2D3 regions showed S. sacchari n. sp. to differ from all other Steinernema species and to belong to a new monophyletic group, the ‘Cameroonian’ clade, consisting of S. cameroonense, S. nyetense and S. sacchari n. sp. This group is closely related to the feltiae-kraussei-oregonense Clade III.

In: Nematology

Abstract

Two Hemicycliophora species, H. lutosa and H. typica, found in samples from fallow soil and sugarcane soil in South Africa, were studied morphologically and, for the first time, molecularly. Diagnostic PCR-IT-rRNA-RFLP profiles generated by five restriction enzymes are provided. Study of phylogenetic relationships using D2-D3 expansion segment of 28S rRNA gene sequences revealed that H. lutosa was related to H. poranga. Hemicycliophora lutosa and H. poranga are compared morphologically. SEM photographs are given for H. typica and for H. lutosa for the first time. The male of H. typica represents a first report for South Africa.

In: Nematology

Abstract

A new species of the genus Hirschmanniella, H. kwazuna sp. n., is described from unidentified grass growing in undisturbed veldt from South Africa. Hirschmanniella kwazuna sp. n. is characterised by having a very irregular heat-relaxed body posture, body 1522-2049 μm long, lip region low and rounded with four or five lip annuli, stylet 18-22.5 μm long, lateral field areolated along entire body, spermatheca filled with sperm, tail with 62-81 ventral annuli narrowing to a tip bearing a ventral mucro, angular crystal-like inclusions within body cavity in most of the specimens and phasmid situated 12-24 annuli or 15-26 μm anterior to tail tip. Males, like females, have crystal-like inclusions with the tail curved strongly dorsad in most specimens. Juveniles are similar to females. Molecular sequence analysis using the D2-D3 expansion segments of 28S, partial 18S and ITS rRNA sequences distinguished H. kwazuna sp. n. from H. loofi and other species of the genus. Hirschmanniella spinicaudata is reported from South Africa for the first time and described. Phylogenetic analyses based on analysis of the D2-D3, 18S and ITS rRNA genes are given for eight, ten and five valid and unidentified Hirschmanniella species, respectively.

In: Nematology

Abstract

Neolobocriconema iranense sp. n. is described from a forest in Iran. Females of N. iranense sp. n. are characterised by having a body length of 453 (371-569) μm, 78-87.5 μm long stylet, presence of a single lip annulus of smaller diam. than the adjacent body annulus and which has a smooth margin and four distinct submedian lobes, 37-43 wide, retrorse body annuli with crenate, dentate and lobulate margins, the latter becoming slightly longer on the last few annuli, annuli with numerous longitudinal grooves corresponding with the crenations, vulva without an overhanging dorsal lip and situated on posteriormost three or four annuli, and anus located on the last annulus. The J2 has 12 longitudinal rows of scales and the ?J4 has eight to ten longitudinal rows of broad, irregular scallops. SEM photographs of females are provided. In the presence of a single lip annulus, N. iranense sp. n. comes close to seven of the 13 species in Neolobocriconema. It can, however, be differentiated from them all in characters such as a shorter body length, shorter or longer stylet, different cuticular structures on the annuli, and in the absence of longitudinal rows of scales or scallops.

In: Nematology