(a) Precontact between male and female Leiobunum verrucosum (male left, female right), with legs removed for clarity. (b) Precopulatory position of mating pair. Male pedipalps grasp female behind coxae of second pair of legs; penis is inserted into female's mouth and then positioned at pregenital opening. (c) Ventral view of male L. verrucosum with short penis retracted and extended by hydraulic expansion of hematodocha. (d) Ventral view of male Hadrobunus fusiformis (not included in study but anatomically similar to L. hoffmani) with long penis retracted and extended by protractor muscles. Abbreviations: f, fultura; go, genital operculum; h, hematodocha; m, mouth; p, penis; pgo, pregenital opening; pp, male pedipalp; ppm, penis protractor muscle; s, nuptial gift sac.