Haecker
Diagnosis: External lattice nearly pentagonal, shaped like arrowhead in lateral view. Nasal style with 5 pairs of larger branches and a few smaller, distal, unpaired branches, all in plane parallel to median suture between shell halves. All paired and unpaired branches further branched, distal ends extending to external lattice. Nasal style and 2 secondary lateral styles extend slightly beyond external lattice. Protruding nasal style with terminal crown of 3 or 4 twice-dichotomous short, smooth, terminal branches. Two protruding secondary lateral styles with terminal crowns, generally with only two twice-dichotomous, short, smooth, terminal branches.
Length: 2.0-3.6 mm.