Amphilepis Ljungman 1867

Amphilepis Ljungman, 1867

Diagnosis: Flat disc covered by thin, overlapping scales; obvious radial shields; oral shields usually triangular, sometimes diamond or heart shaped; madreporite often distinct; usually two oral papillae per side of jaw, often with an additional apical papilla (or ventralmost tooth) and/or 1 or 2 distal papillae adjacent to the second oral tentacle pore; second oral tentacle pore opening between first ventral arm plate, outer end of oral shield and oral plates; arms dorso-ventrally flattened and slender; lateral arm plates bearing 3 bluntly pointed arm spines; large tentacle pores, either without tentacle scales, or bearing 1 or 2 per pore.

Geographic range: North Atlantic, SW Iceland, Europe, Mediterranean Sea, North and South Africa, Madagascar, Indonesia, Japan, North Pacific, South America, New Zealand, and Antarctica. Bathymetric range: 18–4829 m.

Type species: Amphilepis norvegica (Ljungman, 1865).

Remarks: The jaw morphology, occasional lack of an apical papilla, and disc scaling in Amphilepis creates a superficial resemblance to some genera in the Amphiuridae. For example, Ophiomonas D’yakonov, 1952 differs from Amphilepis only in having the inner oral papillae more infradental in position, the first oral tentacle scale positioned further into the slit, and the presence of a distal oral papilla adjacent to the second oral tentacle pore (Clark 1970). Clark (1970) concluded that the Amphilepididae should be reduced to the rank of subfamily of Amphiuridae. However, the only cladistic treatment of the Ophiuroidea to date infers Amphilepis to be in a separate superfamily, sister to all other families in the infraorder Gnathophiurina (Smith et al. 1995).

Clark (1970) also suggests that Amphilepis is composed of two groups, 1) a group with relatively narrow teeth, including A. norvegica, A. ingolfiana, A. mobilis, A. platytata and A. scutata, and 2) a group with broad, squared-off teeth with the ventralmost having a median cusp, including A. gymnopora, A. papyracea, A. patens and A. remittens. However, there is intraspecific variation in the shape of the teeth in several species, including A. ingolfiana (see the variation in figures between Mortensen 1933a and Paterson 1985) and the present species. Further quantitative research is required to evaluate these groups.