The neuronal innervation pattern of the subgenual organ complex in Peruphasma schultei (Insecta: Phasmatodea)

Area of Science:

• Entomology
• Neurobiology
• Sensory Ecology

Background:

• Orthopteroid insects possess a subgenual organ complex in the proximal tibia to detect mechanical stimuli like vibrations.
• Stick insects have two closely located chordotonal organs, the subgenual organ and the distal organ, believed to detect substrate vibrations.

Purpose of the Study:

• To investigate the neuroanatomy of the subgenual organ complex in Peruphasma schultei, a New World phasmid.
• To document the neuronal innervation patterns of the subgenual and distal organs in P. schultei.
• To compare the innervation patterns with other New and Old World phasmids to infer phylogenetic information.

Main Methods:

• Detailed neuroanatomical examination of the subgenual organ complex in Peruphasma schultei.
• Documentation of nerve branching patterns innervating the subgenual and distal organs.
• Comparative analysis of innervation patterns with existing data from other phasmid species.

Main Results:

• Peruphasma schultei typically exhibits a distinct nerve branch for both the subgenual organ and the distal organ.
• Variability in innervation was observed for both organs, with a single nerve branch per organ being the most common pattern.
• The subgenual organ's innervation pattern in P. schultei is simpler than in Old World phasmids but similar to another New World phasmid.

Conclusions:

• The neuroanatomy of the subgenual organ complex is generally conserved across stick insects.
• Peripheral neuronal innervation patterns of these sensory organs may serve as valuable indicators of phylogenetic relationships within phasmids.