. Bonner zoologische Monographien. Zoology. FIG. 12. The "anisitsiellid-like" palpus (top) and the "mamersopsid-like" palpus (bottom) are the two types of palpal shape found generally in the Anisitsiellidae- Limnesiidae complex. Palps of two species of Utaxa- tax (compare text and Chapter 6: " Utaxatax'). In Hygrobatoidea () the median eye-spot and pro- peltidium are reduced. Seta "Ce" is found only in Limnocharoidea and Pontarachnoidea (cf Chapter 4). Up to five setae belonging to the coxal plates are found (sCl-sC5). However, some of them are reduced in
. Bonner zoologische Monographien. Zoology. FIG. 12. The "anisitsiellid-like" palpus (top) and the "mamersopsid-like" palpus (bottom) are the two types of palpal shape found generally in the Anisitsiellidae- Limnesiidae complex. Palps of two species of Utaxa- tax (compare text and Chapter 6: " Utaxatax'). In Hygrobatoidea () the median eye-spot and pro- peltidium are reduced. Seta "Ce" is found only in Limnocharoidea and Pontarachnoidea (cf Chapter 4). Up to five setae belonging to the coxal plates are found (sCl-sC5). However, some of them are reduced in different clades (, sC3 is reduced in most Limne- siidae). Legs. The legs are inserted laterally on the coxal plates; in the plesiotypical condition they have six movable segments (trochanter, basifemur, telofemur, genu, tibia and tarsus). Plesiotypically the tarsus has a narrowed distal end but apotypically (as in Hydrach- noidea and Hygrobatoidea () only), it is not narrowed but equipped with a distal excavation (Tu- zovski 1987). In the superfamilies Hydrovolzioidea, Hydrachnoidea and Hygrobatoidea (), basifemur and telofemur are fused, resulting in a five-segmented leg (L1-L5). The leg segments articulate to permit ventral fle- xion. The segments have characteristic complements of setae and solenidia (Fig. 10). The tarsi bear paired claws and claw-like empodia terminally. The inter- pretation of structures such as solenidia and eupathi- dia is disputed between Tuzovski (1987) and Prasad & Cook (1972) or Smith & Cook (1991). Morphology of Hydrachnellae deutonymphs and adults In Hydrachnellae, deutonymphs and adults are quite similar and are therefore discussed together here. Dif- ferences are usually restricted to the extent of sclero- tization and some characters in the genital region. Gnathosoma. The gnathosoma is plesiotypically a sim- ple, short channel, derived from extensions of the pedipalp coxae containing the esophagus (Mitchell 1962). A prolonga
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