Descripteur : Length of the left spicule
Spicules are accessory cuticular pieces, always double in Heligmonellinae (spicules right and left).
During the copulation, spicules are inserted in the vagina of the female to maintain it open.
Both spicules can be of the same length or different lengths.
Spicules are a great value at the specific level but their structure can be appreciated only after they have dissected from the worm and examined at various angles. Generally , short complex spicules are characteristic of primitive forms: during the course of evolution they become longer and more simplified (Chabaud, 1959). However, whithin a single genus (e.g. , Viannaia) spicules may be short and complex or long and simple depending on the species.
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