1	Eyes present	2
–	Eyes absent	10
2	Mouthparts form forward directed cone-like structure under the head, adapted for piercing and sucking	3 [Paranthuridae]
–	Mouthparts not forming ventral cone-like structure, adapted for biting and chewing	6
3	Pereon composed of 7 distinct, well-developed pereonites with 7 pairs of pereopods; pereonite 7 ca. half as long as pereonite 6 and visible laterally	4
–	Pereon composed of 6 distinct pereonites with 6 pairs of pereopods (7th pereopods absent); pereonite 7 very short, < 20% as long as pereonite 6, not visible laterally	5
4	Pleonites 1–5 free, not fused; pleonite 5 ca. 3 × longer than other pleonites (Fig. 5A)	Paranthuraelegans
–	Pleonites 1–5 fused mid-dorsally, but distinct laterally; all pleonites of similar length (Fig. 5B)	Paranthurajaponica
5	Pleonites 1–5 free, separated from each other by dorsal integumental folds; pleonite 1 ca. 2 × longer than pleonite 2 (Fig. 5D)	Colanthurabruscai
–	Pleonites 1–5 dorsally fused, all pleonites of similar length (Fig. 5C)	Califanthurasquamosissima
6	Dorsal surface of pleotelson with median row of spines; uropodal and pleotelsonic margins serratedEndnote 2	Eisothistos sp. A [Expanathuridae]
–	Dorsal surface of pleotelson smooth or ridged, without spines; uropodal and pleotelsonic margins not serrated	7 [Anthuridae]
7	Pleotelson with 3 raised dorsal longitudinal ridges or carinae; uropodal exopods curve up and over base of pleotelson (Fig. 6C)	Haliophasmageminatum
–	Pleotelson without dorsal ridges or carinae; uropodal exopods may or may not curve up over pleotelson	8
8	Pleonites 1–5 fused only along dorsal midline, segments free laterally and visible dorsally; uropodal exopods ca. half length of endopods and pleotelson, curving up and partially over pleotelson base; uropodal endopods narrow, ca. half as wide as pleotelson (Fig. 6A)	Amakusanthuracaliforniensis
–	Pleonites 1–5 completely fused dorsally; uropodal exopods > 50% length of endopods and pleotelson, may or may not cover the pleotelson dorsally; uropodal endopods broad, subequal in width to pleotelson	9
9	Dorsal surface of pereon pigmented, with complete or nearly complete dark rings on pereonites 2–6 and posterior transverse band on pereonite 7; uropodal exopods partially cover dorsal surface of pleotelson (Fig. 6D)	Mesanthuraoccidentalis
–	Dorsal surface of pereon covered with diffuse pigment splotches, but without pigment rings; uropodal exopods do not cover base of pleotelson (Fig. 6B)	Cyathuramunda
10	Uropodal exopods with distinct lateral lobes, exopods overlapping broadly to cover almost entire dorsal surface of pleotelson; uropodal rami nearly reach, but do not exceed, posterior margin of pleotelson; tips of uropodal rami without tufts of stiff setae (Fig. 6F)	Kupellonura sp. A [Hyssuridae]
–	Uropodal exopods without lateral lobes, overlapping only base of pleotelson; uropodal endopod distinctly longer than pleotelson; tips of uropodal rami with tufts of long stiff setae (Fig. 6E)	Ananthuraluna [Antheluridae]