Table 1 Ovipositor muscles of Lariophagus distinguendus (abbreviations in brackets) and their origin, insertion (cf. Additional file 4) and presumed function as verified in the present contribution

1st valvifer-genital membrane muscle (m-1vf-gm)*

Medial surface of the posteroventral part of the 1st valvifer, at the centre between the tergo-valvifer and the intervalvifer articulation (Fig. 6c, d, f)

Anteriorly at the genital membrane (Fig. 4c)

Tensor muscle for stabilization of the 1st valvifer during ovipositor movements

Dorsal 2nd valvifer-venom gland reservoir muscle (m-d-2vf-vr)

Medial surface of the most anterior part of the 2nd valvifer (Fig. 6c–f)

Dorsally at the anterior part of the venom gland reservoir (Fig. 5a, b)

Supporting the discharge of venom gland reservoir secretion and probably of Dufour’s gland secretion, tensor muscle for stabilization of the 2nd valvifer during ovipositor movements

Ventral 2nd valvifer-venom gland reservoir muscle part a (m-v-2vf-vr-a)*

Medial surface of the most anterior part of the 2nd valvifer, ventrally to the origin of m-d-2vf-vr (Fig. 6d–f)

Laterally at the orifice of the venom gland reservoir (Fig. 5c, d)

Increasing the diameter of the orifice of the venom gland reservoir, thus controlling the venom discharge

Ventral 2nd valvifer-venom gland reservoir muscle part b (m-v-2vf-vr-b)*

Medial surface of the most anterior part of the 2nd valvifer, posteroventrally to the origin of m-v-2vf-vr-a (Fig. 6d–f)

Laterally at the orifice of the venom gland reservoir, ventrally to the insertion of m-v-2vf-vr-a, shortly before the orifice of the venom gland reservoir enters the common oviduct (Fig. 5c, d)

Anterior 2nd valvifer-2nd valvula muscle (m-a-2vf-2vv)

Medial region along the anterodorsal arch of the 2nd valvifer (Fig. 6c, d)

At the processus articularis on the 2nd valvula, laterally at the bulbs of the 2nd valvula (Fig. 6f–h)

Pulling of the corresponding bulb of the 2nd valvula dorsad (thus inducing lateral bending movements of the terebra) in the active probing position, assistance in the rotation of the terebra during oviposition process, elevator of the terebra back into its resting position (once withdrawn from the substrate), holding the terebra in resting position

Posterior 2nd valvifer-2nd valvula muscle (m-p-2vf-2vv)

Medial region along the ventral part of the 2nd valvifer (Fig. 6c, d)

At the processus musculares on the 2nd valvula, dorsally at the anteriorly directed horn-like processes of the bulbs of the 2nd valvula (Fig. 6f–h)

Rotation of the terebra during oviposition process, inducing partial deformation of the 2nd valvula by moving its two halves tangentially towards each other, holding of the terebra in the active probing position

Dorsal T9-2nd valvifer muscle part a (m-d-T9-2vf-a)

Lateral region along the posterodorsal part of the female T9, laterally along its dorsomedial ridge (Fig. 6a–d)

Anterior section of the dorsal flange of the 2nd valvifer, posterior to its medial ridge (Fig. 6c, d, f)

Protractor of the 1st valvula: moves the 2nd posteriorly and the female T9 anteriorly towards each other, causing the 1st valvifer to tilt anteriorly and thus the 1st valvula to slide distally relative to the 2nd valvula

Dorsal T9-2nd valvifer muscle part b (m-d-T9-2vf-b)

Medial region along the posterodorsal part of the female T9, ventromedially to its dorsomedial ridge (Fig. 6c, d)

Anterior section of the dorsal flange of the 2nd valvifer via a tendon, ventrally to the insertion of m-d-T9-2vf-a (Fig. 6c, d)

Ventral T9-2nd valvifer muscle (m-v-T9-2vf)

At the cordate apodeme at the anterior margin of the female T9, posteriorly to the tergo-valvifer articulation (Fig. 6c, d)

Medial surface along the posterior section of the dorsal flange of the 2nd valvifer (Fig. 6c, d)

Retractor of the 1st valvula: moves the 2nd anteriorly and the female T9 posteriorly apart from each other, causing the 1st valvifer to tilt posteriorly and thus the 1st valvula to slide proximally relative to the 2nd valvula

Posterior T9-2nd valvifer muscle (m-p-T9-2vf)

Medial surface of the posterodorsal part of the female T9 (Fig. 6c, d)

Median bridge of the 2nd valvifers

Tensor muscle for stabilization by holding the posterior part of the 2nd valvifer in position during ovipositor movements

T9-genital membrane muscle (m-T9-gm)*

Medial surface of the posterodorsal part of the female T9, dorsally of the origin of m-p-T9-2vf (Fig. 6c, d)

Posteriorly at the genital membrane

Tensor muscle for stabilization