Bioacoustics of Lepthyphantes christodeltshev

Description . Since there are only two specimens available (the male holotype and female paratype ) I have left both specimens intact as much as possible, so as to keep them fit for further examination. More detailed examination of the genitalia has to wait until additional material becomes available. The illustrations provided here consequently have to remain more schematic and are meant to enable identification and give insight into their anatomy as much as possible. Male. Species of small size. Colour: Generally light brown, with light grey suffusion on the chelicerae. Sternum and abdomen dark grey. Legs yellow to brown. Abdomen on the dorsal posterior half with three faint chevron markings which are light brown because the grey pigment is lacking there on the otherwise grey abdomen; no white pigment present. Measurements (in mm): total L 1.9, cephalothorax L 0.85, W 0.65 , abdomen L 1.05, W 0.60 , H 0.60; chelicerae L 0.28, W 0.15 , height of clypeus 0.12. All eyes of about same size (∅ 0.075), only AME much smaller (∅ 0.037); PME separated by 0.4 times ∅ of PME, AME by 0.67 times ∅ of AME. Chelicerae . With coarse stridulating files, ridges 0.009 mm apart. Three relatively large pro-marginal teeth of equal size, five small retro-marginal teeth of equal size. Legs: I II III IV palp Fe 1.06 0.95 0.82 1.06 0.27 Pa 0.25 0.25 0.21 0.22 0.11 Ti 1.06 0.98 0.75 - 0.15 Mt 0.99 0.89 0.72 - - Ta 0.66 0.59 0.44 - 0.30 Fe I with one pro-lateral spine, other femora spineless; all tibiae with two dorsal spines, Ti I with pro-lateral (l’) and retro-lateral (l”) spine, Ti II with l”-spine only. TmI 0.19. Position of basal d-spine on tibia I 0.33, length of spine 0.20, ∅ 0.087. Metatarsi spineless. Male palp. Tibia without apophysis; only scar of dorsal spine visible, spine itself broken off. Cymbium simple, without basal dorsal protrusion. Paracymbium ( Figs 1, 2 ) with a sharply pointed tooth at the postero-ventral corner and an equally slender tooth more forward, below inside the tub-shaped element, hidden behind a lobe-like retro-lateral extension of the ventral margin of the element. Suprategular apophysis straight and pointed. Lamella ( Figs 1, 3, 4 ) broad where it emerges from the radix, then narrowing to a slender, curved central section and with a forked end, the two branches at a perpendicular angle. Radix ( Fig. 4 ) with clear Fickert's Gland. Embolus slender, modestly sickle-shaped; no denticles at base visible (as present in some Tenuiphantes species). Other details were difficult to distinguish without damaging the palp of the holotype , which was left intact as much as possible. Female. Coloration as in male. Abdomen with the faint chevron markings over the whole dorsal surface. Measurements (in mm): total L 2.2, cephalothorax L 0.80, W 0.65 , abdomen L 1.45, W 0.95 , H 0.90; chelicerae L 0.37, W 0.17 , height of clypeus 0.1. Eyes . All eyes of about the same size (∅ 0.062), only AME slightly smaller (∅ 0.050); PME separated by 0.6 times ∅ of PME, AME by 0.38 times ∅ of AME. Chelicerae . Stridulating files coarse. Three relatively large pro-marginal teeth of equal size, five small retro-marginal teeth of equal size. Legs: I II III IV Fe 0.96 0.90 0.76 1.00 Pa 0.25 0.25 0.21 0.21 Ti 1.00 0.90 0.69 1.00 Mt 0.84 0.75 0.61 0.83 Ta 0.59 0.56 0.52 0.51 Fe I with one pro-lateral spine, other femora spineless; all tibiae with two dorsal spines, Ti I with pro-lateral (l’) and retro-lateral (l”) spine, Ti II with l”-spine only. TmI 0.16. Position of basal d-spine on tibia I 0.36, length of spine 0.26, ∅ 0.087. Metatarsi spineless. Epigyne and vulval structures ( Figs 5-6 ): The organ is not protruding, but is flush with the ventral surface. The basal part of the scape (ventral view, Fig. 5 ) is more or less oval, widest in the middle, and projects slightly over the epigastric furrow. A small parmula is visible, but mostly hidden below the scape. A narrow, slit-like space separates the scape from the lateral parts of the epigyne. At either side of the scape, between the widest part of the basal part of the scape and the posterior-most tips of the lateral ventral surface, a rounded structure ("lateral lobe") is visible, the function of which is unknown. The dorsal view ( Fig. 6 ) reveals the knob-shaped parmula with a socket on top of the broad, squarish distal part of the scape; the entrances of the sperm ducts are discernible through the structure (situated at the ventral surface) laterally at the tip just mesally of a socket. I have not flattened the scape to investigate its precise anatomy because I have only this single specimen, but it looks as if the scape is not very flexible; the middle and terminal sections of the scape seem to arise from the dorsal side of the basal section of the scape, not at the tip but slightly more to the front (anterior direction) of that part of the scape. This would agree with the only slightly sickle-shaped embolus of the male (which has to fit into the curved section of the scape). In dorsal view it is clear that the rounded structures at either side if the scape are the extensions of the thin but well-chitinized "posterior median plate", which in this species is a dorsal median plate with concave distal margin; the "lateral lobes" appear to be separated from the bordering lateral ventral surface by a fissure; the lateral lobes and median plate should together be homologous with the posterior median plate in other Lepthyphantes species.