What is it about?

This research was aimed to study the musculature of wood-inhabiting nematode Rhabditolaimus ulmi using confocal microscopy. Lip region hexagonal; pharynx diplogastrid. Corpus is the fused stegostoma, procorpus and metacorpus, with six glands opening in stegostoma and the corpus limen; stegostoma with large dorsal bulge; posterior bulb with 2 circles of dilators and basal sphincter. Female genital muscles have 4-radial symmetry. Two vaginal constrictors and 4 pairs of dilators of two types are connected to the vagina-uterus opening; four dilators run perpendicular to the uterus axis and connected to the uterine muscular corset. The sphincter between intestine and cloaca consists of the middle ring with two pairs of processes connected ventrally with intestinal fasciculi and dorsally with body wall. The ring contains the inner biconical X-structure. Male: the gubernaculum has the dorsal erector and a pair of transverse muscles. The wide gubernacular spicule protractor envelops spicules anteriorly. Ventral tail muscle is unpaired, 9 pairs of serial diagonal muscles are located beneath the body wall muscles, followed by 3 pairs of postcloacal oblique muscles of tail. Anal depressors are a pair of transverse muscles with expanded middle globular parts. The copulatory muscles are of the Rhabditidae and Cephalobidae type. The muscle characters code of previously published tabular key for 15 muscle characters: 73422-22144-42223; it can be used for phylogenetic reconstructions.

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Why is it important?

The newly revealed morphological characters may be easy combined with the molecular characters for the integrative phylogeny and diagnostics of helminths, and may explain sexual dimorphism of muscle systems.


Research results is important to understand the evolution of sexual relations of helminths and of their diagnostics and the life histories, namely their complicated life cycles assiciated with the wooden plants diseases.

Dr Alexander Yuryevich Ryss
Zoological Institute of the Russian Academy of Sciences

Read the Original

This page is a summary of: The pharyngeal and genitalia-associated muscles of Rhabditolaimus ulmi (Nematoda: Chromodorea: Rhabditida: Diplogastridae), Nematology, December 2022, Brill,
DOI: 10.1163/15685411-bja10216.
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