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ventrite and sternite in Ciidae


Cited by Professor Cristiano lopez-Andrade:
What we see in Coleoptera are not exatly the mesosternum and metasternum. The sclerites that would originally be in those position, or most of them, are indeed invaginated and form part of the endoskeleton. What we do see are the fusion of preepisternum and katepisternum, forming the meso- and metaventrite, the latter being attached to each other in adults Myxophaga and Polyphaga. There is no “proventrite”, because the prosternum is the true anterior thoracic sternum.

“Ventrite” means a ventral, visible sclerite. This term only applies to sclerites that are completely exposed.

In the case of ventral abdominal sclerites, nowadays several authors call them abdominal “ventrites”, rather than “sternites” or “urosternites” to avoid confusion in counting. The first and second “sternites” are not visible in most beetles. So, the first visible abdominal “sternite” is, indeed, the third sclerite. If one call it “ventrite” (which is a visible sclerite by definition), it’d be the first ventrite. In the case of ciids, we have five exposed abdominal “sclerites”, so we have five abdominal ventrites. The fifth abdominal ventrite is, consequently, the seventh abdominal sternite. The sclerites forming the abdominal terminalia are not fully exposed, so they cannot be called “ventrites”.

The eight sternite is the correct name. The apodemes of the ninth segment (genital ring) of ciids is a matter of much discussion. Authors have called it “ninth tergite”, “ninth sternite”, “ninth segment”. It’s not exactly the spiculum ventrale of other Coleoptera, because it’s possibly not originated only from the ninth sternite, but from the whole segment, forming somewhat a membranous chamber with lateral apodemes converging anteriorly.