Mononchoides composticola n. sp. (Nematoda:Diplogastridae) associated with composting processes: morphological, molecular and autecological characterisation

Mononchoides composticola n. sp. was isolated from compost and is described based on light and scanning electron microscopy, supplemented with SSU rDNA sequence data. It is characterised by the following features: a denticulate ridge in addition to the dorsal claw-like tooth, a small tooth-like swelling at the stegostom base, ca 26 longitudinal ridges on the female body, a uterine sac associated with two dumb-bell-shaped pouches, relatively small spicules (30-38 µm long), a simple gubernaculum shorter than half the spicule length, the genital subventral papillae (v6) consisting of three very small papillae, and a long filiform tail (female: 391-550 µm, 18-26 anal body diam.; male: 304-548 µm, 19-30 anal body diam.). Phylogenetic analyses placed the new species together with M. striatus, sister to Tylopharynx foetida. Since the use of nematodes as functional indicators often relies on the allocation of nematodes to feeding groups, experiments were performed to elucidate the feeding strategy of the new species. Both its ability to move actively to bacterial food sources and to prey on other compost nematodes were tested. Mononchoides composticola n. sp. actively moved towards the compost bacterium Achromobacter, a taxis that was temperature dependent, and also preyed on other nematodes. Predation was selective, with a higher predation rate on the relatively small and slow-moving Rhabditella sp. than on the considerably larger and more motile Rhabditis (Poikilolaimus) sp. Adults of M. composticola n. sp. have a dual feeding behaviour and can apparently alternate between bacterial and nematode prey