Morphological and molecular characterisation and diagnostics of some species of Scutellonema Andrássy, 1958 (Tylenchida: Hoplolaimidae) with a molecular phylogeny of the genus
Date
2013Author
Van den Berg, Esther
Tiedt, Louwrens R.
Coyne, Daniel L.
Ploeg, Antoon T.
Navas-Cortés, Juan A.
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Show full item recordAbstract
Scutellonema spp. are widely distributed across tropical and subtropical regions of the world and are associated with
numerous agricultural and horticultural crops. Identification of many Scutellonema species is not always reliable, in part because
many species share very similar diagnostic characters. In this study, we provide morphological and molecular characterisation of S.
brachyurus from the USA and South Africa, S. bradys from Nigeria and three unidentified species from California, USA, New Zealand
and Burkina Faso. Morphological descriptions, measurements, light and scanning electron microscopic photos and drawings are given
for S. brachyurus. Females of S. brachyurus from the USA (type A) and South Africa (type B) showed a significant variation in the
number of sectors and blocks on the lip annuli, ranging from about 4-12 and from 8-20, respectively. Molecular analysis using the D2-
D3 of 28S rRNA, ITS rRNA and the COI mtDNA gene sequences revealed two distinct genotypes within S. brachyurus samples: type
A (samples from USA, Italy, Korea, Taiwan) and type B (South Africa). Multivariate analyses determined that S. brachyurus from the
USA and Taiwan (type A) differed from that from South Africa (type B) mainly in body, tail and DGO lengths, and ratios b , c , c and
V. Phylogenetic relationships within Scutellonema are given as inferred from the analyses of the D2-D3 of 28S rRNA, ITS rRNA and
the COI mtDNA gene sequences. PCR-RFLP diagnostic profiles and PCR with species-specific primers are developed for the studied
Scutellonema species