No evidence for regeneration of pectines in the scorpion Euscorpius italicus (Herbst, 1800)

Although scorpions have comparatively low regenerative potential, legs and pedipalps are able to regenerate some structures in an often incomplete manner. The most intriguing scorpion appendages are the ventrally located pectines. These organs are equipped with numerous sensilla that scan the substrate for mechanosensory- and chemosensory cues. Due to their ventral position and frequent substrate contact, pectines are vulnerable to traumatic injuries. Pecten malformations have been hypothesized to be the result of incomplete regeneration. To investigate their regeneration capabilities, the pectines of postembryonic stages of Euscorpius italicus (Herbst, 1800) were amputated before the second moult at three different positions. Data on intermoult periods and the number of pectinal teeth were gathered for approximately 2.5 years. The regeneration process on exuviae of up to six moulting events was documented by photographs and confocal laser-scanning microscopy. Regardless of the amputation site, no evidence for regenerative capabilities of pectines in E. italicus could be reported. Thus, incomplete regenerations mentioned in the literature are likely the result of simple wound healing. Depending on habitat complexity, substrate contact time of the pectines seem to differ, which might be interpreted as a trade-off between highest sensory input and the avoidance of traumatic injury of the pectines.