Squamodisc

Squamodiscs are usually made up of scales embedded in the epidermis, which appear from the outside as rodlets arranged in rows.

[2] According to the classical book of Bychowsky (1967),[3] “the Diplectanidae] have special paired attaching formations lying above the disc and also partially on it, on the dorsal and ventral sides in the shape of small rounded convexities equipped with numerous [...] thorn-shaped little hooks or thin thread-like plates located more or less in concentric rows ("squamodisc")".

Ultrastructural studies of squamodiscs [4][1] have shown that they include epidermally-embedded spines which are covered by the outer epidermal membrane.

The spines are composed of a moderately electron-dense material with denser fibrils embedded within it.

A diplectanid genus Squamodiscus Yamaguti, 1934 was created but is now considered[5] a synonym of Diplectanum Diesing, 1858.

Squamodiscs of the diplectanid Pseudorhabdosynochus epinepheli . Left, ventral squamodisc; right, dorsal squamodisc.
Scanning electron microscopy of the scales in the squamodisc of the diplectanid Pseudorhabdosynochus jeanloui [ 1 ] Bar: 2 μm.