Aulodrilus limnobius Bretscher 1899

Aulodrilus limnobius Bretscher, 1899

Records. Gránický Brook, Znojmo, 48°51'60"N / 16°01'33"E, lgt. PP, det. PP. (2005); Drietomice River, Starý Hrozenkov, 48°57'13"N / 17°52'29"E, lgt. PP, det. PP (2005); Trusovický Brook, Jívová, 49°42'27"N / 17°21'40"E, lgt. KB, det. PP; Olešná River, Zvole, 49°29'26"N / 16°09'44"E, lgt. KB, det. PP (2002); Nectava River, Březinky, 49°39'24"N / 16°46'52"E, lgt. KB, det. PP (2002); Okluky River, Uherský Ostroh, 48°59'38"N / 17°24'07"E, lgt. H, det. PP (2002); Farský Brook, Trhové Sviny, 48°50'24"N / 14°37'55"E, lgt. JZ, det. PP (2002); all specimens were immature.

Characteristics of sites. All records were from small and middle-sized brooks (3rd and 4th Strahler order, river width up to 5 m) with a bottom substrate dominated by sand, gravel, and stones. Most of these highland stretches had a natural morphology (with buffer strips) and extensively used (cropland, grassland), partially forested catchments. The brooks have good water quality (from oligo- to beta-mesosaprobity), with one exception of lowland stream (Okluky River, alpha-mesosaprobity).

Ecology. Being a detritophagous species, A. limnobius occurs from hyporhithral to potamal, and also has been collected from standing water areas including deeper, profundal habitats (Hörner et al. 2002; Šporka 2003; Alves et al. 2008). It can tolerate intermediate eutrophication (Verdonschot 2006) and organic pollution from oligo- to alpha-mesosaprobity (Hörner et al. 2002). Microhabitat preferences of fine substrates rich in organic material (pelal, psamal and argylal) have been reported (Šporka 2003; Alves et al. 2008). Among oligochaetes, A. limnobius belongs to K-strategists (Šporka 2003) with one reproductive cycle per year, mostly realised by asexual reproduction (architomy); mature specimens are rare (Timm & Veldhijzen van Zanten 2002). Worms burrow in sediment, where they build reinforced tubes of silt (Timm & Veldhijzen van Zanten 2002).

Morphology. Aulodrilus limnobius has characteristic bifid crotchets, with up to 10 chaetae per bundle (all with shorter upper teeth, and occasionally with wing-like dilations of the distal ends of the chaetae in posterior segments), and an unsegmented tail, serving as a respiratory organ—typical for this genus. It can be distinguished from its congeners known to occur in the Czech Republic— A. pigueti, A japonicus, and A. pluriseta —by a lack of hair chaetae (Timm & Veldhijzen van Zanten 2002; van den Hoek & Verdonschot 2005).

Distribution. This cosmopolitan species has been recorded in most of European countries, absent only in Austria, the UK, Croatia, Denmark, Greece, Slovenia, and Portugal (Timm & Giani 2004). According to Fauna Europaea (Timm & Giani 2004), the species was found also in the Czech Republic, but unfortunately, the source of this data is not available.