Polymorphism in the Ostertagiinae Lopez-Neyra, 1947 and comments on the systematics of these nematodes

Abstract

A list of 19 polymorphic species of the genera Ostertagia, Orloffia, Teladorsagia, Marshallagia and Spiculopteragia is presented. The morphs of the polymorphic species in question have identical females and show similarities in some male features, e.g. the structure of the oesophagus, the synlophe and the shape of the rays of the copulatory bursa. However, they differ by characters which are recognised as generic features, e.g. the structure of spicules, gubernaculum and genital cone. The presence or lack of minor morphs is a generic feature in the Ostertagiinae. Each polymorphic genus has a defined type of minor morph.

Spiculopteragia mathevossianiRuchliadev, 1948 is the minor morph ofSpiculopteragia spiculoptera(Gushanskaya, 1931): molecular evidence

“…The posterior part of the worm was cleared and preserved in Amman lactophenol on a glass side. They were identified as S. spiculoptera morph spiculoptera or morph mathevossiani, and O. leptospicularis morph leptospicularis or morph kolchida by using morphological features according to Skrjabin et al [35] and Dróżdż [10,13]. These specimens are available upon request to the authors.…”

“…Accurate identification of trichostrongyle nematodes in wild ungulates is important for studying their susceptibility to contamination from or towards do-mestic ruminants. Moreover, the status of some taxa remains controversial since the description was made of morphologically distinct but genetically identical adult male Ostertagiinae [13,24,26]. Morphological polymorphism was only detected in males and affects the morphology and length of spicules and the genital cone [13].…”

“…Moreover, the status of some taxa remains controversial since the description was made of morphologically distinct but genetically identical adult male Ostertagiinae [13,24,26]. Morphological polymorphism was only detected in males and affects the morphology and length of spicules and the genital cone [13]. Several approaches have supported the hypothesis of male polymorphism in different species of Ostertagiinae as seen with cross-breeding experiments [27,38], morphological observations [13,28,30], and allozyme studies [17].…”

“…Morphological polymorphism was only detected in males and affects the morphology and length of spicules and the genital cone [13]. Several approaches have supported the hypothesis of male polymorphism in different species of Ostertagiinae as seen with cross-breeding experiments [27,38], morphological observations [13,28,30], and allozyme studies [17]. Comparisons of genetic sequences from both Internal Transcribed Spacers (ITS-1 and ITS-2) which are known as specific level markers are now used to detect polymorphism [18,23,42].…”

“…The hypothesis of male polymorphism, however, renders its taxonomy and systematics confusing, especially for the potential survey of its distribution pattern among domestic livestock and reservoir hosts. According to the synonyms reviewed by Durette-Desset [15], Spiculopteragia mathevossiani Ruchliadev, 1948 (= Rinadia schulzi (Grigoryan, 1951) = S. caucasica (Assadov, 1955) = S. pavloskyi (Kadenatsii and Andreeva, 1957) = S. quadrifurcata (Andrews, 1964)) has been suggested as a minor morph of Spiculopteragia spiculoptera (Gushanskaya, 1931) (= S. boehmi (Gebauer, 1932) = S. kutkascheni (Assadov, 1952) = S. pigulevski (Ruchliadev, 1961)) [13,24,27]. Consequently, the objective of this study was to test whether individuals representing each of these morphological forms could be consistently differentiated by their sequences of either ND4 or ITS-2.…”