Tanytarsus usmaensis. Prepupa larva. The same, magnified. Arrow: imaginal disk 

... Additional teeth on the claws of the posterior parapods. In a few species, 1-3 small additional teeth are present on small claws of the posterior parapods. These teeth are found in T. eminulus and T. striatulus ( Fig. 34, 35). A large number of small teeth is found on the inner margin of sev- eral claws of the posterior parapods in species of Virgatanytarsus (Fig. 6). 4 Morphology of the anal papillae. In most species, the anal papillae are longer than wide and are sometimes constricted at the base (Fig. 10). In T. sylvaticus and T. spec. Lonnekermeer the ...

... (e.g. T. nemorosus, T. lactescens and T. palettaris). The frontal apotome in most species is yellow, but it may be partly or entirely brown (e.g. T. gracilentus, T. ejuncidus, T. longitarsis and T. heusdensis). In T. pallidicornis a longitudinal brown line is present on the frontal apotome. 6 The shape of clypeal seta S3. This hair may be simple (Fig. 13 ) or branched (Fig. 12). 7 The presence of teeth on the second segment of labral seta II (Fig. 19). Labral seta II is the largest of several labral setae and consists of a small, basal segment and a large, terminal seg- ment. Teeth may be present or absent on this second segment. This is a difficult character, and is to be studied in ...

... Number and colour of the dorsal mandibular teeth and paramandibular plate. In most spe- cies, a single dorsal tooth is present on the outer margin of the mandible (Fig.43). This tooth is yellow in most species. ...

... 22). A short, blunt spur is present in T. lactescens and T. signatus (Fig. 28). 11 Length of 1 st antennal segment and ratio of 1st antennal segment and segments 2-5 (antennal ratio: AR). In some very similar species, such as T. longitarsis and T. ejuncidus the length of anten- nal segment 1 constitutes one of the few discriminating features (Fig. 32, 33). The AR is used to separate the T. mendax/occultus species group from T. volgensis. 12 Sclerotisation of 2 nd antennal segment . In most species, the 2 nd antennal segment is sclerot- ised over 4/5 th of its length (Fig.15, 17). Less sclerotisation is found in larvae of T. gr. eminulus and T. signatus, which have the 2 nd antennal ...

... segment . In most species, the 2 nd antennal segment is sclerot- ised over 4/5 th of its length (Fig.15, 17). Less sclerotisation is found in larvae of T. gr. eminulus and T. signatus, which have the 2 nd antennal segment sclerotised over 2/3 rd of the length of the segment (Fig.16); in T. palettaris, only the basal 1/3 rd part is sclerotised (Fig. 23). Unique within the West-European species of the genus is the absence of sclerotisation of the base of the 2 nd an- tennal segment in T. signatus (Fig.28). 13 Sclerotisation of 3 rd antennal segment . In most species, the 3rd antennal segment is sclerot- ised over its entire length. In T. mendax and T. occultus however the 3rd segment ...

... a useful character as these colours fade over time. In some closely related species, such as T. lestagei and T. medius this character is useful to separate these species: in T. lestagei, the anterior range of the occipital margin is pale, its lateral ranges are dark; by contrast, T. medius has a unicolourous, brownish-black postoccipital margin ( Fig. ...

... can often be seen through the head capsule. -Thorax swollen in the last phase of the 4 th instar. In these last days before pupating, the pupal characters become visible; the larva becomes a prepupa. In the swollen thorax, imaginal disks can be discerned. Pupal characters, like point patches and spine bands of the tergites often are very distinct (Fig. 3). These characters may serve as an important check for the identification of the larvae. The key by Langton (1991) is recommended here. In prepupae, colour features like a darkened gula are always fully developed. The same, magnified. Arrow: imaginal disk 1a Supra-anal seta longer than anal papillae (Fig. 4) Subkey 1 1b Supra-anal seta ...

... Clypeal setae S3 branched (Fig. 12, 16 and 17) 5 4b Clypeal setae S3 not branched (Fig. 13) 9 5a Basal 2/3 rd part of antennal segment 2 sclerotised (Fig. 14); labral seta II toothed T. heusdensis Additional characters: Gula with large dark spot; frontal apotome brown to weakly light brown; head width 200 µm (n=1), less than in species of T. pallidicornis species group. Brooks. 5b Basal 4/5 th part of antennal segment 2 ...

... ditches and non acidic lakes. Also in slowly flowing waters. In weakly buffered moorland pools and upper reaches of lowland streams often found co-occurring with T. buchonius. Head width 220-260 µm (n=3), 1 st antennal segment 190 µm (n=1). 9a Antennal pedestal with large, inwardly curved spur (Fig. 22) or with a rather short spur with acute tip (Fig. 23); central mental tooth brown 10 9b Antennal pedestal without spur or with short spur with blunt tip; central mental tooth yellow with brown lateral margin 11 10a Antennal pedestal with long, inwardly curved spur with acute tip (Fig. 22) T. brundini/curticornis Additional characters: Dorsal mandibular tooth ...

... Antennal pedestal with rather short, acute spur (Fig. 23) T. "spec. Landweerven" Additional characters: Dorsal mandibular tooth ...

... Antennal pedestal without spur; sclerotisation of 2 nd antennal segment extending to base of the segment (Fig. 30-32); clypeal seta 3 not branched (Fig. 28) 3 3a 2 nd antennal segment sclerotised over half, up to two-thirds of its length (Fig. 31); pedes- tals of Lauterborn organs partly sclerotised (T. eminulus species group) 4 3b 2 nd antennal segment sclerotised over 4/5 th of its length; pedestals of Lauterborn organs not or partly sclerotised ...

... Antennal pedestal without spur; sclerotisation of 2 nd antennal segment extending to base of the segment (Fig. 30-32); clypeal seta 3 not branched (Fig. 28) 3 3a 2 nd antennal segment sclerotised over half, up to two-thirds of its length (Fig. 31); pedes- tals of Lauterborn organs partly sclerotised (T. eminulus species group) 4 3b 2 nd antennal segment sclerotised over 4/5 th of its length; pedestals of Lauterborn organs not or partly sclerotised (Fig. 30, 32) 9 4a Frontal apotome brown or light brown; posterior region of head brownish 5 4b Frontal apotome entirely yellowish; ...

... (Fig. 30-32); clypeal seta 3 not branched (Fig. 28) 3 3a 2 nd antennal segment sclerotised over half, up to two-thirds of its length (Fig. 31); pedes- tals of Lauterborn organs partly sclerotised (T. eminulus species group) 4 3b 2 nd antennal segment sclerotised over 4/5 th of its length; pedestals of Lauterborn organs not or partly sclerotised (Fig. 30, 32) 9 4a Frontal apotome brown or light brown; posterior region of head brownish 5 4b Frontal apotome entirely yellowish; posterior region of head various 6 5a Gula (Fig. 37) and frontal apotome brown; length of 1 st antennal segment 132-147 µm (Fig. 33) T. ...

... partly sclerotised (T. eminulus species group) 4 3b 2 nd antennal segment sclerotised over 4/5 th of its length; pedestals of Lauterborn organs not or partly sclerotised (Fig. 30, 32) 9 4a Frontal apotome brown or light brown; posterior region of head brownish 5 4b Frontal apotome entirely yellowish; posterior region of head various 6 5a Gula (Fig. 37) and frontal apotome brown; length of 1 st antennal segment 132-147 µm (Fig. 33) T. ...

... over 4/5 th of its length; pedestals of Lauterborn organs not or partly sclerotised (Fig. 30, 32) 9 4a Frontal apotome brown or light brown; posterior region of head brownish 5 4b Frontal apotome entirely yellowish; posterior region of head various 6 5a Gula (Fig. 37) and frontal apotome brown; length of 1 st antennal segment 132-147 µm (Fig. 33) T. ...

... Gula and frontal apotome light brown; length of 1 st μ antennal segment 158-180 m (Fig. 34) T. ...

... canals (with water current), poorly buffered moorland pools. 6a One up to a few of the small claws of posterior parapods carry accessory teeth (Fig. 35, 36); gula yellow, at most vaguely brownish at base 7 6b All claws of posterior parapods distally smooth; gula with large, brown or brownish- black patch (T. lestagei species aggregate) 8 7a Labral seta II toothed; gula and genae yellow (Fig. 38) T. striatulus Additional characters: LO/ant. segm. 3-5 >3.3. 1 st antennal segment 198 µm (n=1) ...

... moorland pools. 6a One up to a few of the small claws of posterior parapods carry accessory teeth (Fig. 35, 36); gula yellow, at most vaguely brownish at base 7 6b All claws of posterior parapods distally smooth; gula with large, brown or brownish- black patch (T. lestagei species aggregate) 8 7a Labral seta II toothed; gula and genae yellow (Fig. 38) T. striatulus Additional characters: LO/ant. segm. 3-5 >3.3. 1 st antennal segment 198 µm (n=1) (Ekrem 2004) Moorland pools. 7b Labral seta II smooth; basis of gula and posterior area of genae light brown (Fig. 39) T. eminulus Additional characters: LO/ant. segm. 3-5 <2.7. 1 st antennal segment 136-162 µm (Ekrem 2004). 11a Mandible ...

... gula with large, brown or brownish- black patch (T. lestagei species aggregate) 8 7a Labral seta II toothed; gula and genae yellow (Fig. 38) T. striatulus Additional characters: LO/ant. segm. 3-5 >3.3. 1 st antennal segment 198 µm (n=1) (Ekrem 2004) Moorland pools. 7b Labral seta II smooth; basis of gula and posterior area of genae light brown (Fig. 39) T. eminulus Additional characters: LO/ant. segm. 3-5 <2.7. 1 st antennal segment 136-162 µm (Ekrem 2004). 11a Mandible with yellow dorsal tooth accompanied by a second, smaller dorsal tooth and small, brown paramandibular plate; distal tooth of mandible brown, three yellowish- brown inner teeth present (Fig. 43); LO/ant. segm. 3-5 = ...

... area of genae light brown (Fig. 39) T. eminulus Additional characters: LO/ant. segm. 3-5 <2.7. 1 st antennal segment 136-162 µm (Ekrem 2004). 11a Mandible with yellow dorsal tooth accompanied by a second, smaller dorsal tooth and small, brown paramandibular plate; distal tooth of mandible brown, three yellowish- brown inner teeth present (Fig. 43); LO/ant. segm. 3-5 = 1.9-2.3 T. bathophilus Additional characters: Posterior region of head brown; gula with black patch; postoc- cipital plate and margin brownish-black; labral seta II ...

... Mandible without paramandibular plate 14 14a 3 rd antennal segment sclerotised in the distal 2/3 rd part only (Fig. 32); AR <2.3; ratio of 3 rd antennal segment/4 th antennal segment = 2.5-2.8; LO/ant. segm. 3-5 = 1.5-2; pre- mandible with 4 teeth T. mendax/T. occultus Additional characters: According to Ekrem (2004), the ratio LO/ant. segm. 3-5 ranges from 1,6-1,98 in T. mendax to 2,03-2,26 in T. occultus. Head width 320-330 µm (n = ...