Hentschel, 1923
Definition: Encrusting, massive, lobate, fan-shaped or branching Myxillina. Specialised ectosomal skeleton composed of tornotes with smooth or apically spined bases, arranged as bouquets or lying paratangential or perpendicular to the surface. Choanosomal skeleton composed of isotropic, anisotropic or plumoreticulate tracts of smooth or partially spined monactinal or diactinal choanosomal megascleres, sometimes echinated by small acantho-styles. Spongin development variable, usually consisting of light spongin cementing spicules together at their nodes, but sometimes with heavy fibres. Microscleres include anchorate isochelae and/or derivatives (spatulate, unguiferous isochelae, sometimes anisochelate), and smooth sigmas (Myxilla incrustans chSEM).
Remarks: 18 nominal genera are included in this family, of which 6 are recognised here as valid, although several of these are have two or more recognized subgenera.
Source: Desqueyroux-Faúndez and Van Soest, 1996.
Genera represented in the area:
Melonanchora Carter, 1874 (type species M . elliptica Carter, 1874): fistular growth form, with paper-like thin ectosome composed of smooth ectosomal tylotes, smooth choanosomal styles, microscleres are melonchelas or spherancres (modified anchorate isochelae) and normal anchorate chelae.
Myxilla Schmidt, 1862 (type species Halichondria rosacea Lieberkühn, 1869) (syn. Dendoryx Gray, 1867; Emplocus Gray, 1867; Tereus Gray, 1867; Stegxella Bowerbank, 1874; Hastatus Vosmaer, 1880; Stelodoryx Topsent, 1904; Ectyomyxilla of authors (nomen nudum of Lundbeck, 1909); Crellomyxilla Dendy, 1924; Burtonanchora De Laubenfels, 1936; Jelissima De Laubenfels, 1936; Pseudomyxilla Koltun, 1955): the ectosomal tylotes with have variable terminations: mucronate, frequently with 1 or few prominent spines, or exceptionally entirely smooth, forming both a tangential skeleton and vertical spicule brushes; choanosomal spicules stylote, usually styles with or without spined bases, forming a tight meshed isotropic reticulation or looser isodictyal skeleton; echinating acanthostyles often present but sometimes lost; microscleres are anchorate spatulate or unguiferate isochelae often of several sizes, and sigmas (the latter sometimes lost). Several of the genera synonymized here with Myxilla were previously considered valid by various authors. They differ from Myxilla s.s. in presumably artificial characters: presence of a second, smaller category of acanthostyles (Crellomyxilla ), the possession of unguiferate iscochelae next to to spatulate ones (Stelodoryx ), possession of smooth instead of spined styles (Burtonanchora ). Such characters, though hardly likely to be of phylogenetic significance, still may serve to separate species among the large amount of species answering to a wide definition of Myxilla employed here. They may be conveniently used as subgenera.
Plocamiancora : encrusting, with "plocamiid" skeleton (i.e. with basal isotropic reticulation of single acanthostrongyles and long protruding styles); microscleres spatulate anchorate or polydentate unguiferate isochelae.
Styloptilon Cabioch, 1968 (type species S . ancoratum Cabioch, 1968): encrusting; with a plumose skeleton of bundles of larger acanthostyles echinated by shorter acanthostyles; tornotes anisoxeote; microscleres anchorate chelae and sigmas.
Species included:
Melonanchora elliptica
Myxilla fimbriata
Myxilla incrustans
Myxilla inequitornota
Myxilla iotrochotina
Myxilla rosacea
Styloptilon ancoratum
Species not treated here:
Melonanchora emphysema (Schmidt, 1875), Norway, Iceland, deep water
Myxilla brunnea (Hansen, 1885), Norway, Iceland, deep water
Myxilla perspinosa Lundbeck (1902), Iceland, deep water
Myxilla tarifensis Carballo and Garcia-Gomez (1996), Straits of Gibraltar
Stelodoryx pluridentata (Lundbeck, 1905), Icealnd, deep water
Stelodoryx procera Topsent (1892), North Atlantic, deep water
Plocamiancora arndti Alander (1942), Swedish fjords, Scotland, deep water