Bioacoustics of Micropholcus

Description (Old World taxa). Male. Measurements . Total body length ~ 2.3–3.9. Carapace width 0.8–1.5. Diameter PME 60–100 µm; diameter AME usually 35–55 µm, in M. bukidnon sp. nov. only 15 µm. Tibia 1 length 5.0–10.2. Tibia 1 L / d : 57–85. Leg formula 1243. Diameters of leg femora (at half length) 80–150 µm, of leg tibiae 75–120 µm. Colour (in ethanol). Prosoma and legs pale ochre-yellow to grey, carapace with dark pattern, legs with darker patellae and tibia-metatarsus joints; abdomen ochre-grey to whitish, monochromous or with whitish marks. Live specimens (Figs 3 , 4 ) similar in colour but slightly darker. Body . Ocular area slightly raised (distinct in frontal view; Fig. 5 ). Carapace without thoracic groove. Clypeus unmodified. Sternum slightly wider than long, unmodified. Abdomen approximately twice as long as wide. Gonopore with four (rarely five) epiandrous spigots (Fig. 10 ; see also Huber 2000 : fig. 123; Huber 2011 : fig. 99). ALS with one strongly widened spigot, one long pointed spigot, and six cylindrical spigots (Fig. 9 ; see also Huber 2000 : figs 158, 159; Huber 2011 : fig. 100); PMS with two conical spigots; PLS without spigots. Chelicerae . Chelicerae with pair of strong frontal apophyses provided with conical or globular, strongly sculptured modified hairs (Fig. 6 ; see also Huber 2011 : fig. 98), usually with one or two pairs of proximal processes; without stridulatory files. Palps . Palpal coxa unmodified. Trochanter with retrolateral-ventral apophysis usually with distinctive modified (short cylindrical) hair at tip (Fig. 9 A – D ), modified hair absent in M. bukidnon sp. nov. Femur variable in shape, often with rounded processes (usually ventrally and retrolaterally, sometimes also dorsally). Femur-patella joints shifted towards prolateral side. Tibia larger than femur, with two trichobothria. Tibia-tarsus joints shifted towards retrolateral side. Palpal tarsus with large capsulate tarsal organ (Fig. 11 H, I ; see also Huber 2011 : fig. 97), outer diameter 30–35 µm, diameter of opening 15–20 µm; more open (almost exposed) in M. bukidnon sp. nov. (Fig. 11 J ). Procursus complex, often with distinct dorsal hinged process (e. g., Figs 16 C , 43 C , 52 C ), in most species with transparent prolateral membranous flap densely set with teeth (Figs 7 A, D , 8 B ). Genital bulb with distinct proximal sclerite connecting to tarsus, membranous or partly sclerotised embolus, and variably complex set of sclerotised apophyses, sometimes likely homologues of the Pholcus ‘ appendix’ and ‘ uncus’, sometimes of uncertain homology (Figs 7 B, F , 8 C, E, F, H ). Legs . Without spines and curved hairs. Without slender metatarsal hairs (cf. Huber et al. 2023 a ). Without sexually dimorphic short vertical hairs. Chemoreceptive hairs ~ 20–25 µm long, with few side branches (Fig. 12 A, H ), mostly near leg tips. Retrolateral trichobothrium of tibia 1 at 5–10 % of tibia length. Prolateral trichobothrium absent on tibia 1, present on tibiae 2–4. Base of trichobothria evenly rounded, without proximal ridge (cf. Fig. 11 D ). Legs with roundish cuticular plates (Fig. 12 E ; diameter ~ 6–8 µm) and rimmed pores (Fig. 12 B ; outer diameter 2 µm, diameter of opening 0.2 µm) apparently on all leg segments. Tarsus 1 with ~ 20–30 pseudosegments, distally usually fairly distinct. Leg tarsal organs capsulate (Figs 11 E – G , 12 F ; diameter 12–17 µm, diameter of opening 5–7 µm). Tarsus 4 with single row of comb-hairs on prolateral side (Fig. 12 G, H ; see also Huber 2011 : fig. 96). Main tarsal claws with ~ 10 teeth (Fig. 12 C, D ). Female. In general, very similar to males (Figs 3 , 4 ). Legs slightly shorter than in males (male / female tibia 1 length: ~ 1.1–1.4, but sample sizes mostly small); tibia 1 length 4.3–9.1. Palpal tarsal organ smaller than in males (outer diameter: 18–25 µm, diameter of opening: 6–10 µm). Palpal tarsus ending distally in pointed tip and pair of strong dorsal hairs (Fig. 5 G, H ). Spinnerets, leg hairs, cuticular plates, rimmed pores, comb-hairs, leg tarsal organs, and tarsal claws as in male. Epigynum anterior plate usually weakly sclerotised, with rounded process (‘ knob’; Fig. 11 A – C ) in varying position; posterior epigynal plate short and indistinct. Internal genitalia often complex, highly variable, with distinct pair of pore plates.