First reports of Sphaeronema alni parasitizing downy birch and Hemicycliophora aquatica in the UK

In June 2008, the endoparasitic nematode Sphaeronema alni Turkina & Chizhov, 1986 was found in roots and associated soil from Betula pubescens collected from a riverbank, near Sandsend, Whitby, UK (OS: NZ 783 133 GB). A small number of sedentary females of the endoparasitic nematode were found causing necrosis and forming syncytia on the lateral roots. The site was resampled in August and September, but only evidence of feeding sites was observed. Degenerate males of this species are known, but were not found. Juveniles from this population were smaller with a longer tail length than in previously recorded specimens (n = 9): L = 0.41 ± 0.04 (0.36-0.45) mm versus 0.53 (0.44-0.63) mm; tail = 93.4 ± 6.8 (84.9-101.1) μm versus 83 (65-98) μm. The sedentary females were in poor condition and their morphology is not reported here. This is a new UK record for this genus and species, which is also reported from Russia (Turkina & Chizhov, 1986; Subbotin, 1989) and Poland (Brzeski, 1998).

Hemicycliophora aquatica (Micoletzky, 1913) Loos, 1948, a rare sheath nematode usually found in wet habitats, was also recorded in the associated soil for the first time in the UK. Morphometrics are summarized thus (n = 6): L = 1.3 ± 0.05 (1.2-1.4) mm, stylet = 124.4 ± 2.9 (121.1-127.3) μm, a = 25.7 ± 0.84 (24.9-27.1), b = 6.0 ± 0.3 (5.6-6.3), V = 83.3± 0.7 (82.1-84), tail = 111 ± 7.03 (105-121) μm, c = 11.7 ± 0.4 (11.3-12.1), R = 294 ± 7.6 (287-306). The variability of the pharyngeal bulb (smaller bulb making isthmus appear longer), the intermediate position of the stylet length and spermatheca distinct but with all females unfertilized, adds support to the proposal by Brzeski (1998) that H. macristhmus Loof, 1968 is conspecific with H. aquatica. Specimens of both species were preserved in TAF and are deposited as voucher specimens in The Food and Environment Research Agency nematode collection.