Subgenus Hymedesmia (Hymedesmia) Bowerbank, 1864

Hymedesmia species are thin encrusting with an ectosomal skeleton of tornotes unoriented at surface and in bundles in choanosome. One or two sizes of acanthostyles stand erect on substrate. Subgenus Hymedesmia has arcuate isochelas; subgenus Stylopus lacks isochelas (Van Soest 2002 [2004]a). Worldwide there are 157 recognized Hymedesmia (Hymedesmia) species (de Voogd, et al. 2023). Hymedesmia (Hymedesmia) species are found in all Oceans except the Arctic and Red Sea and from intertidal to 2640 m depth; depth distribution is discontinuous over this range. We have restricted our comparison to North Pacific species to determine the new species status of those discussed below.