The Congrogadinae consists of 19 species of elongate fishes which reach a maximum length of about 40 cm. They occur primarily in the coral reefs and sea-grass meadows of the Indo-West Pacific. Mature ovarian eggs were found to possess hooked, multi-armed projections distributed equidistantly over their surfaces. Each projection has a central pedicel perpendicular to the chorion which raises it above the egg surface. A few of these hooks give rise to long filaments. The numbers of hooks, arms per hook, and filaments vary among taxa. Hook size and shape changes with egg size. On eggs 70 μm in diameter, hooks begin as small, button-shaped knobs about 2 μm across, gradually becoming stalked and composed of four V-shaped subunits. These eventually form a cruciform structure, about 200 μm across, which bears recurved hooks; these occur on eggs over 3000 μm in diameter. Hooks stop increasing in size before the egg attains its maximum diameter. Filaments increase in length as the hooks grow, reaching a final length of at least 7500 μm. In extruded eggs, the filaments (but not the hooks) come loose from the chorion to tangle with the hooks and filaments of adjacent eggs. This forms an egg mass which is probably guarded by the male. Although the data are prone to homoplasy, two alternative cladograms based on egg surface morphology were constructed. Changes to cladograms existing in the literature involved the genera Halimuraena, Haliophis, Halidesmus, and Blennodesmus. These genera might be monophyletic, based on the occurrence of the hooks in deep pits. The monophyly of the subgenus Congrogadoides is further corroborated by the predominance of three-armed hooks on their egg surfaces.
Monitoring morphology evolution within block copolymer microparticles during dispersion polymerisation in supercritical carbon dioxide: a high pressure SAXS study