remarks. It differs from Amphiplecta tripleura Funakawa, 1995bin the width/length ratio of its cephalis, in having less numerous, smaller pores as well as a smoother shell wall and in the dorsal shoulder being less developed but covered by the shell wall; fromA. cylindrocephala Dumitrica, 1973 in the thickness of its wall, the shape of its cephalis and in having less numerous, smaller pores. Contrary to what is seen in A. tripleura and A. acrostoma Haeckel, 1887 (Petrushevskaya, 1971; Funakawa, 1994, 1995b), arch dl(or d-al according to Funakawa 1995b) is not recognizable in our species, and arch al is not distinguishable from the rest of the wall. This renders the genus assignment questionable; however, the fact that arch ad is clearly expressed as a bump external to the rest of the cephalis and the overall shape of the cephalis seems to indicate a close relationship of A.? satoshii with those two species.

Amphiplecta? satoshii also differs from Lophophaena galeataehrenberg, 1874 (see also Ogane et al., 2009, pl. 79, fig. 1a–c) and L. capito ehrenberg, 1874 (see also Ogane et al., 2009, pl. 79, fig. 2a–c) in its elongated cephalis with a flattened top, the presence of a cluster of apical spines instead of just a unique spine and, more importantly, in its inner cephalic structure: L. galeata seems, based on the Ogane et al. (2009) pictures, to have well-expressed arches ap reminiscent of the ones in Lithomelissa ehrenbergi Bütschli, 1882 (see more in the Description and Remarks section of Lithomelissa celsagula n. sp.).