Cryo-SEM micrographs of tarsal structures of female Monochamus alternatus.
a. Ventral view of a female’s foretarsus. Note the distinctly bilobed pad in the 3rd tarsomere. b. A single part of the paired claws, equipped with sharp edges ventrally and dorsally (female). c. Terminally spatulate, adhesive setae on the first tarsomere of a female’s foreleg. The arrows indicate the opposite, anisotropical orientation of setal terminals, with adhesive surfaces facing each other, according to the bilobed pad of the first tarsomere as mentioned for (a). d. Cross section of setae, showing their flattened, ribbon-like shape (female). e. Dorsal view of male’s second tarsomere, laterally bearing numerous long tactile setae. f. Ventro-lateral view of the setal terminal, illustrating the tapered tip and spindle-shaped adhesive area surrounded by a ridge (arrow head), and dorsally situated setules (female). g. Broadened, flattened basal shafts of setae (female). h. Lateral details of terminals of spatula-shaped female’s tarsal adhesive setae, showing 5–10 setules (se) at their dorsal side, suggesting the avoidance of coagulation of the extremely thin (ca. 0.3 μm) terminals. t1, 1st tarsomere; t2, 2nd tarsomere; t3, 3rd tarsomere; t5, 5th tarsomere; ts, tactile setae; cl, claw; do, dorsal; se, setule; ve, ventral. Note that t4, the 4th tarsomere is hidden and not shown in the image