Molecular and morphological characterisation of two reproductively isolated species with mirror-image anatomy (Nematoda: Cephalobidae)

In: Nematology
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Detailed descriptions are given of the amphimictic nematode strains PS1158, PS2052 and PS2160, which are unusual in that they only differ in predominant body handedness. Although these strains are morphologically identical in all other respects, published reproductive data and new DNA sequence data of the D2/D3 region of the large subunit rRNA gene show that they do represent two separate species. On the basis of comparison with type material, the left-handed strains PS1158 and PS2160 are identified as Acrobeloides bodenheimeri, and the right-handed strain PS2052 as A. camberenensis, which is re-instated as a valid species. A. bodenheimeri and its relatives exhibit various types of diagnostic and taxonomic problems at species level, and it is shown that D2/D3 sequence data provide an important new diagnostic tool for addressing these problems. Phylogenetic analysis shows that two right-handed parthenogenetic strains identified as A. maximus represent a third species which is more closely related to A. camberenensis than to A. bodenheimeri. Caracterisation morphologique et moleculaire de deux especes intersteriles de chiralite contraire (Nematoda: Cephalobidae) - Une description detaillee est donnee des souches amphimictiques de nematodes PS1158, PS2052 et PS2160, souches inhabituelles car differant par la chiralite du corps. Bien que ces souches soient morphologiquement identiques sous tout autre rapport, les resultats publies de tests de croisement et de nouvelles donnees concernant la sequence d'ADN de la region D2/D3 du gene de la grosse sous-unite d'ARN ribosomal montrent qu'elles representent en fait deux especes distinctes. Se fondant sur une comparaison avec le materiel type, les souches sinistres PS1158 et PS2160 sont identifiees comme Acrobeloides bodenheimeri et la souche dextre PS2052 comme A. camberenensis, ainsi retabli comme espece valide. A. bodenheimeri et les especes proches posent differents problemes diagnostiques et taxinomiques au niveau specifique, et nous montrons que les donnees de sequence D2/D3 fournissent un nouvel outil diagnostique important pour aborder ces problemes. L'analyse phylogenetique montre que deux souches parthenogenetiques dextres identifiees comme A. maximus representent en fait une troisieme espece, plus proche de A. camberenensis que de A. bodenheimeri.

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