Sequential frames of mating in Petrobiellus akkesiensis, Case VI in Table 1 (captured from File S3), viewed from the bottom. Counters indicate the time from the commencement of the experiment. Arrows indicate the outline of the spermatophores, to show their approximate dimension. A At 45 sec after the commencement of the experiment (ACE), while exploring the ovipositor with his penis, the male has already prepared the styli IX to hold the ovipositor, i.e., the stylus on the side closer to the partner (left in this frame) is bent forward, whereas the other stylus (right in this frame) is stretched backward. B At 1 min 15 sec ACE, the male protrudes his penis at a right angle and grasps the basal part of the ovipositor with the distally-curved penis. The male’s ventral sacs in the abdominal segments VII and VI begin to swell. C At 1 min 50 sec ACE, the ventral sacs in the abdominal segments V to III also swell, and the spermatophore becomes visible. D At 6 min 59 sec ACE, the spermatophore has reached its maximum size and is clearly visible at the basal part of the ovipositor. E At 8 min 3 sec ACE, the male’s ventral sacs begin to deflate. F At 8 min 42 sec ACE, all ventral sacs have deflated. G At 9 min 1 sec ACE, the spermatophore begins to diminish. H At 9 min 28 sec ACE, the male’s styli IX release the ovipositor, but the penis still maintains its hold. I At 13 min 35 sec ACE, the spermatophore has diminished to its minimum size. — Abbreviations: An – antenna; Ce – cercus; CF – caudal filament; Cx6–9 – coxites VI to IX; Ov – ovipositor; Pa9 – paramere IX; Pe – penis; Sp – spermatophore; St6–9 – styli VI to IX; T7–10 – abdominal terga VII to X; VS3–7 – ventral sacs III to VII. — Scale bars: A – 2 mm; B, C, E, H, I – 1 mm; D, F, G – 500 µm.