Morphological and molecular studies on Heterodera sacchari, H. goldeni and H. leuceilyma (Nematoda: Heteroderidae)

Abstract

AbstractHeterodera sacchari, H. leuceilyma and H. goldeni are closely related members of the H. sacchari species complex, which is mainly characterised and distinguished from all other described Heterodera species by the presence of finger-like projections of the strongly developed underbridge in the vulval cone of the cysts. Males are rare in all three species and are described here in H. goldeni for the first time. Reproduction appears to be parthenogenetic. There are only minor morphological distinctions between the three species, particularly after our present studies have emended their original descriptions from various populations. Heterodera sacchari and H. goldeni showed differences in the ITS-rRNA gene sequences. Heterodera sacchari was described and reliably identified from many tropical African countries, H. leuceilyma is known only from Florida, USA, and H. goldeni has been identified in Egypt, Israel and Iran. All three species have grasses and other Poaceae as hosts, H. sacchari commonly attacking rice and sugarcane, and H. goldeni reproducing successfully on sugarcane ratoon seedlings. Morphological data emending the descriptions of H. sacchari, H. goldeni and H. leuceilyma from various populations are presented and discussed along with their host and distribution. Molecular characterisation of H. sacchari and H. goldeni is provided. An analysis of phylogenetic relationships within species of the sacchari-group using ITS-rRNA gene sequences is also presented.