Hydrachnidia 377 9-123: Hydrachnidia, plesiotypical idiosoma organization, dorsal view (from Davids et al. 2007). Terminology following Lundblad 1927 (in parentheses: following Zahvatkin 1952, after Tuzovskij 1987). Explanation of abbreviations: Zahvatkin 1952 Lundblad 1927 – Fr: Frontale Fch: frontalis chelicerarum Dgl-1: Dorsoglandulare 1 (Antenniforme) Vi: verticalis interna Dgl-2: Dorsoglandulare 2 Oe: occipitalis externa Dgl-3: Dorsoglandulare 3 Hi: humeralis interna Dgl-4: Dorsoglandulare 4 Sci: scapularis interna Dgl-5: Dorsoglandulare 5 Li: lumbalis interna Dgl-6: Dorsoglandulare 6 Si: sacralis interna Dgl-7: Dorsoglandulare 7 (= Vgl-4, Ventroglandulare 4) Ve: verticalis externa Lgl-1: Lateroglandulare 1 He: humeralis externa Lgl-2: Lateroglandulare 2 Sce: scapularis externa Lgl-3: Lateroglandulare 3 Le: lumbalis externa Lgl-4: Lateroglandulare 4 Oi: occipitalis interna Postoc: Postoculare Fp: frontalis pedipalporum Preoc.: Preoculare – Dc-1-4: Dorsocentralia 1-4 – Dl-1-4: Dorsolateralia 1-4 © Springer-Verlag Berlin Heidelberg 2016 R. Gerecke, T. Gledhill, V. Pešić, H. Smit, Süßwasserfauna von Mitteleuropa, Bd. 7/2-3 Chelicerata, Süßwasserfauna von Mitteleuropa, DOI 10.1007/978-3-8274-2689-5_1 378 Hydrachnidia 9-124: Hydrachnidia, plesiotypical idiosoma organization, ventral view (from Davids et al. 2007). Terminol- ogy following Lundblad 1927 (in parentheses, following Zahvatkin 1952, after Tuzovskij 1987). Explanation of abbreviations: Ac-1-3: Acetabulum 1-3 An: Anus Genpl: Genital plate Pregen: Pregenital plate Postgen: Postgenital plate Zahvatkin 1952 Lundblad 1927 – Cx-1-4: first to fourth coxae Hv: humeralis ventralis Cxgl-2: Coxoglandulare 2 (Cxgl-1 and -3 not existing) Sce: scapularis externa Cxgl-4: Coxoglandulare 4 Si: sacralis interna Dgl-7: Dorsoglandulare 7 (= Vgl-4: Ventroglandulare 4) Pi: praeanalis interna Vgl-1: Ventroglandulare 1 Se: sacralis externa Vgl-2: Ventroglandulare 2 Ci: caudalis interna Vgl-3: Ventroglandulare 3 – V-1-4: Ventralia 1-4 Hydrachnidia 379 9-125: a-d, Hydrachnidia, gnathosoma and its appendages in lateral view, example of Thyopsis cancellata (Protz, 1896) (from Davids et al. 2007); a, gnathosoma and left palp; b, right palp laterally (indicating num- bering of segments and traditional segment terminology); c, chelicera; d, palp indicating important measure- ment distances (L = length, H = height); e, Hydrachnidia, schematical lateral view; dashed lines indicate hy- pothetical segment borders (for abbreviations see Figs 8-75-76, frontal eye posterodorsally, paired lateral eyes posterolaterally from Dgl-2; setae Ce reduced in most taxa, developed only in postlarval instars of Limnochares and Pontarachnidae; after Tuzovskij 1987). 380 Hydrachnidia 9-126: Hydrachnidia, habitus (from Davids et al. 2007); a, Wandesia female, ventral view (from Di Sabatino et al. 2002); b, Hydrovolzia male, ventral view (detail: glandulare); c, Hydrovolzia male, dorsal view (arrow: dorsal furrow), d, Panisopsis male, dorsal view (from Di Sabatino et al. 2002), e, Sperchon male, ventral view (detail: glandulare); f, Arrenurus male, ventral view; g, Aturus female, ventral view, h, Ljania male, ventral view. 381 Hydrachnidia, key to superfamilies 1 Legs with three claw-like, sickle-shaped appendages: paired, ventrally pectinate, true claws, and an empodium similar in shape, but without pectination; idiosoma vermiform, without muscle attachment sclerites; rod-shaped frontal sclerite (8-79 a) with one unpaired, and three paired setae; eyes strongly reduced or completely absent; legs covered by rather uniform hairs over the segment surface ("hyper- trichous"); palp compact (8-80 a), P-1-3 fused, P-4+5 forming a functional unit; P-5 without claws, bearing one stiff terminal seta; pale reddish species of interstitial waters. ....................... ����������������������������������������������������������������������������������������������������Stygothrombioidea (Vol. I, page 289) – Legs with two (or occasionally less) claw-like appendages (8-79 h-k): empodium not claw like; claws rarely with ventral pectination; idiosoma rarely vermiform (8-78 a), with or without muscle attachment sclerites; if a rod-shaped frontal sclerite is present (e. g., 8-79 b), never bearing an unpaired anterior seta; eyes various, in most cases with paired lateral eyes, sometimes also with an unpaired frontal eye (8- 79 e, g); legs rarely hypertrichous, in general with distal margin setae stronger than setae on remaining segment surface (8-79 h-k); palp various (8-80 b, e-f, h-i, l-o), P-5 generally with claws, rarely bearing only one stiff terminal seta. ��������������������������������������������������������������������������������������������������������������������2 2 (1) Palp chelate (P-4 forming a chela with P-5) and P-1 longer than P-2, P-3 longer than P-4, P-4 reduced in size, maximum height of palps in P-1, the following segments gradually tapering (8-80 b); gnatho- soma in ventral view characteristically narrowed at the base of the slender, pointed rostrum (8-80 b, d), chelicerae needle-like (basal segment + claw fused to a single unit, 8-80 c); genital field (8-81 c) with maximum width in the anterior part, bearing numerous acetabula located anteriorly from, or on the level of, the anterior margin of the gonopore; rather large, globular red species of standing waters. ....... ���������������������������������������������������������������������������������������������������������� Hydrachnoidea (Vol. I, page 333) – If palp chelate, neither P-1 longer than P-2, nor P-4 shorter than P-3, maximum height of palps in general in segments P-2-4 (8-80 e-f, h-i, l-o); gnathosomal rostrum, if present, generally not pointed (8-80 i), chelicerae two-segmented, not needle-like (8-80 k, p); genital field various in shape, if numer- ous acetabula present, they are arranged in a different manner or the genital field has not its maximum width anteriorly from the gonopore (8-81 a-b, e, h, m-o); larger or smaller species, various in colour and shape. 3 3 (2) Lateral eyes, if present, incorporated into a frontal sclerite (8-79 b-d, f); palps not chelate (8-80 e-f, h), in some groups transformed by fusion of segments (e. g., 8-80 f), claws of P-5 straight (8-80 h) or reduced to fine tips (8-80 f); mouth opening surrounded by a circular, membranous fringe (8-80 g) or (in Apheviderulicidae, so far not recorded from the study area, 8-80 f) reduced to a fine slit in the centre of a conspiciously enlarged gnathosoma; acetabula numerous, or on roundish sclerites flanking the gonopore (8-81 a), or in the membranous perigenital area (8-81 b), or extremely reduced in size scattered all over the membranous idiosoma surface (8-81 d); glandular openings occasionally with semilunar, fan-shaped openings (8-79 f, 8-81 a); large, red species of temporary and permanent standing waters (outside the study area also pale inhabitants of springs and interstitial waters). ............................. ��������������������������������������������������������������������������������������������������������������������Eylaoidea (Vol. I, page 301) – Lateral eyes, if present, not incorporated into a frontal sclerite (but occasionally very close to such a sclerite, 8-79 g); palps various in shape, P-5 in general with hook-like distal claw setae (8-80 i, l-o); mouth opening various, but neither surrounded by a circular fringe, nor in the centre of an extremely enlarged idiosoma; acetabula in three pairs or numerous (8-81 e-o), in rare cases invisible by light microscope; glandular openings never fan-shaped (8-79 e, g). ��������������������������������������������������������������4 4 (3) I/II-L directed anteriorly, III/IV-L directed posteriorly, the two leg groups separated by a large interspace (8-78 b); genital field minute, in the centre of the ventral idiosoma, devoid of acetabula (these numerous, mostly invisible in light microscope and inserted as minute cups on the medial coxal surface); in the postgenital area two large unpaired plates, the anterior one with the anal pore, or all perigenital plates and platelets fused to a shield embracing the genital field; dorsum with two shields in "T" position (8- 78 c); glandular openings and setae on paired paletelets (8-78 b, arrow); flattened inhabitants of springs, cascades and interstital waters. Hydrovolzioidea (Vol. I, page 294) – If legs arranged in two groups, they are not orientated into two opposite directions, and the interspace is less extended (8-78 a, d); genital field various, (with the exception of the marine Pontarachnidae) always with groups of acetabula arranged in various ways (8-81 e-o); if dorsal shields present, not arranged in a "T" position; glandularia and their associated setae together on one single platelet (8-79 e, g, arrow) ����������������������������������������������������������������������������������������������������������������������������������������������������������������5 382 Hydrachnidia, key to superfamilies 9-127: Hydrachnidia (from Davids et al. 2007); a-g, frontal sclerites, h-k, legs; a, Stygothrombium; b, Limno- chares; c-d, Eylais; e, Euthyas; f, Piersigia; g, Hydryphantes; h, Parathyas IV-L; i, Hydryphantes (Polyhydry- phantes), IV-L; k, Trichothyas I-L. Hydrachnidia, key to superfamilies 383 5 (4) Palps chelate (8-77 a-b, d, 8-80 i, arrow: P-4 with a dorsal extension or a heavy dorsal seta dorsally flanking P-5); idiosoma smooth or with regularly arranged muscle insertion sclerites (8-78 d), only in exceptional cases with extended dorsal and ventral shields; acetabula