Authors

Z Bartonicek²; I Martinek²; EM Shilland¹; ME Spencer Jones¹; JS Hernández-Orts²;  ¹ Natural History Museum, UK;  ² Institute of Parasitology Czech Acadamy of Science, Czechia

Discussion

Introduction:

Rotifers, or wheel animals, are a paraphyletic assemblage of ~2,000 species with remarkably diverse morphologies, ecologies and reproductive modes. Most rotifer species have a predominantly free-living lifestyle in aquatic and terrestrial environments. Strikingly, an endoparasitic lifestyle has been reported for a few species, mostly belonging to the genera Albertia and Balatro (Monogononta: Dicranophoridae). These parasitic rotifers live in the guts of earthworms or freshwater oligochaetes. In the UK, a single record of an endoparasitic rotifer, Albertia vermiculus Dujardin 1838, was reported from the earthworm Allolobophora caliginosa (Savigny) in Cardiff more than sixty years ago, with no more parasitic rotifers recorded since. In this study, we provide new data on endoparasitic rotifers of earthworms in the UK.

 

Methods:

In total, 289 earthworms were collected between March 2023 and February 2024 across two sites in Newport, Wales (n = 209) and two sites near Cudham, London (n = 80). Worms were examined for rotifer infections by dissection under a binocular microscope. All encountered parasitic rotifers were identified using light microscopy. High-resolution microphotographs of rotifers were taken, with samples retained for later morphological and molecular analysis.

 

Results:

Two species of endoparasitic rotifers were identified. In Wales, Albertia vermiculus was found in six earthworms (prevalence: 3.6%, mean intensity: 5.2 rotifers per infected worm). Here, all rotifers were collected from Aporrectodea longa (Ude). In earthworms from London, the rotifers Balatro calvus Claperéde, 1867 (prevalence: 7.5%, mean intensity: 5.5 rotifers per infected worm) and A. vermiculus (prevalence: 5%, mean intensity: 5.8 rotifers per infected worm) were found. Eiseniella tetraedra (Savigny) served as host for B. calvus, and Aporrectodea longa and A. caliginosa (Savigny) were the hosts of A. vermiculus in London.

This provides the first UK record for B. calvus. Furthermore, A. longa, A. caliginosa and E. tetraedra represent new host records for parasitic rotifers.

 

Conclusions:

The results and samples generated here not only inform our understanding of the parasitic rotifer diversity in the UK but will also be crucial for subsequent planned evolutionary studies into the evolution of parasitism within the Rotifera.