Pyrgoma Leach, 1817

Ross, A. & Newman, William A., 2002, A review of the Pyrgoma cancellatum species complex (Cirripedia: Pyrgomatidae), Journal of Natural History 36 (4), pp. 407-421 : 408-409

Genus Pyrgoma Leach, 1817

Pyrgoma Leach, 1817b: 67 ; Leach, 1818: 171; Leach, 1824: 171; Darwin, 1854: 354 (synonymy); Ross and Newman, 1973: 58 (synonymy); Holthuis, 1982: 316 (nomenclature).

Paranobia Galkin, 1986: 1293 .

De®nition (emended). Wall single-plated, solid, ¯at to dome-shaped, radially ribbed, margin crenate; basis with ladder to arch-like calcareous structures alternating between solid, medially sulcate, longitudinal ribs that terminate at suture with wall; scutum and tergum separable; scutum transversely elongate, limbus adductorum large, extending below true basal margin, rostral tooth present; tergum with true spur, slight fenestra present between opposed terga.

Type species. Pyrgoma cancellata Leach, 1818 , by subsequent monotypy ( Leach, 1818: 171).

Remarks. Ross and Newman (1973) considered this genus to be monotypic. However, in re-evaluating all of the descriptions and illustrations of P. cancellatum and related forms, and in light of new knowledge of these as well as other pyrgomatines, we conclude there are at least ®ve species represented. Within this genus we informally recognize two groups, one with a small narrow tergum that lacks tergal crests ( P. cancellatum and P. japonica ) and the other with a large broad tergum having small to large, simple or complex tergal crests ( P. kuri , P. projectum and P. sinica ). However, there are presently no major characters separating them and therefore they are not recognized as distinct taxa.

The major character distinguishing Pyrgoma from all other pyrgomatines is the presence of passageways through the basis (®gure 1). It is through these that we believe the barnacle mediates its relationship with the host coral (Ross and Newman, 1973, 2000a).