articulamentum

articulamentum

[är‚tik·yə·lə′men·təm]
(invertebrate zoology)
The innermost layer of a calcareous plate in a chiton.
References in periodicals archive ?
Articulamentum: Apophyses triangular, widely separated by a straight sinus (Fig.
Comparison and remarks: This species was originally placed in the genus Lepidochitona, mainly due to the morphology of the ventral girdle scales and to the characters of the articulamentum, but was later considered as belonging to Chaetopleura (see Rolan 2005; Sirenko 2006).
A unique head valve from ST03 has a shell scar due to injury, which caused the development of a new insertion plate under the older one in the articulamentum.
Canals close to the articulamentum layer curve upward around the layer and run longitudinally parallel to the dorsal surface before curving to the dorsal surface or extending to the anterior margin.
The plates are composed of calcium carbonate and are composed of three layers, outer or dorsal tegmentum, articulamentum, and ventral hypostracum.
In the intermediate and tail plates the presence of the articulamentum layer, which is not penetrated by the canals, causes changes in the canal shape and orientation as they curve around and extend over the articulamentum layer.
Sirenko's subsequent investigations proved that these characters (1993), as well as variation in the articulamentum (1997) are useful in the analysis of chiton phylogeny.
The importance of the development of articulamentum for taxonomy of chitons (Mollusca, Polyplacophora).
Articulamentum well developed, whitish, apophyses evenly rounded, jugal sinus wide, slit formula of insertion plates 9-10/1/8-10, slits inequidistant, slit rays distinctly punctured, teeth sharp, smooth, eaves solid (Fig.
Articulamentum white, insertion plates well developed, apophyses short and trapezoidal, more triangular in valve ii.
Articulamentum white, strongly developed, forming large insertion plates.