1	Body of adult female distinctly segmented with clear division of head (cephalon), thoracic (pereon), and abdominal (pleon) regions	2 [Bopyridae and Ionidae]
–	Body of adult female sac-like, with at most weak segmentation visible	18 [Dajidae and Hemioniscidae]
2	Adult female body broadly oval; pleon strongly torsioned and reflexed forward over pereon; head without eyes, deeply embedded in pereon, anterior margin covered by oostegites; pleomeres 3–6 fused medially; branchial parasite of deep-water crangonid shrimps of genus Glyphocrangon (Fig. 13B)	Bathygygegrandis
–	Female body not as above, pleon not strongly reflexed over pereon	3
3	Female pleon with pleopods and/or elongated lateral plates (epimeres or pleural lamellae) clearly noticeable in dorsal view	4
–	Female pleon without pleopods or elongated lateral plates noticeable in dorsal view	12
4	Lateral plates of pleon and/or pleopods conspicuously elongate, foliaceous, or lanceolate, with or without digitated or crenulated margins	5
–	Lateral plates of pleon and pleopods relatively short, distal margins of pleopods mostly rounded	10
5	Adult female with elongated lateral plates fringed with long, branched processes; branchial parasite of ghost shrimps of genus Neotrypaea (Fig. 13A)	Ionecornuta
–	Adult female with or without lateral plates, but lateral plates not as above if present	6
6	Adult female body nearly oval, with oostegites conspicuously visible dorsally arching over margins of head and pereon; head longer than wide, deeply immersed in pereon, eyes absent; pereomere 6 much longer than other pereo­meres, pereomeres 1–5 concave anteriorly, pereomeres 6 and 7 concave posteriorly; pleon with “triramous appendages” in appearance, but each one consists of a foliaceous lanceolate lateral plate and identical biramous pleopod; branchial parasite of hermit crabs Parapagurodeslaurentae and P.makarovi (Fig. 13C)	Anathelgeshyphalus
–	Adult female body not as above, pereomere 6 subequal in length to other pereomeres; pleon with lateral plates and pleopods not appearing like triramous appendages	7
7	Adult females with pair of dorsolateral papillae on pleomere 1; pleon with long, narrow biramous pleopods arising from thin peduncle or stem on each segment, without lateral plates; head slightly wider than long, bilobate, eyes absent; abdominal parasite of mud shrimps of genus Upogebia (Fig. 13F)	Phyllodurusabdominalis
–	Adult females without dorsolateral papillae on pleomere 1; pleomeres with both elongated lateral plates and pleopods, but morphology of pleopods not as above	8
8	Pleon of adult females enclosed by tentacular-like, elongated lanceolate lateral plates and pleopodal exopods, each with deeply digitate margins, ventral surface covered partially by smaller foliate pleopodal endopods with crenulated margins; head completely embedded in pereon, dorsal surface divided into two large sub-oval lobes, eyes absent; branchial parasite of grapsid crab Pachygrapsuscrassipes (Fig. 13D)	Leidyainfelix
–	Pleon of adult females with lateral plates and pleopods not as above; head not bilobate	9
9	Adult female body ~ 2 × longer than wide, pyriform in shape; head slightly wider than long, eyes absent; coxal plates very large, overlapping, and extending well beyond lateral margins of pereomeres; pleon obscured by prominent ovate lateral plates and long, biramous lanceolate pleopods; branchial parasite of pelagic galatheid “red crab” Pleuroncodesplanipes (Fig. 13E)	Munidionpleuroncodis
–	Adult female body slightly longer than wide; head subcircular, eyes absent; coxal plates prominent but not widely extended on pereomeres 1–4; lateral edges on convex side of pereomeres 5–7 produced into slender points reflexed back over dorsum; pleomeres 1–5 with dentate-margined lanceolate lateral plates and similar biramous pleopods; branchial parasite of hermit crab Isochelespilosus (Fig. 14D)	Asymmetrioneambodistorta
10	Adult female head somewhat bilobate, eyes absent; pereomeres 1–6 with sharply pointed tergal projections on longer side of body; pleomeres 1–5 with short lateral plates and distally rounded uniramous pleopods; branchial parasite of several genera of crangonid and hippolytid shrimps (e.g., Crangon, Eualus) (Fig. 14A)	Argeiapugettensis
–	Adult females not as above; head not bilobate, with or without eyes; pereon without sharp tergal projections; pleopods biramous	11
11	Adult female head wider than long with rounded anterior and posterior margins, eyes absent; narrow and rudimentary coxal plates on pereomeres 3 and 4 on both sides of body; branchial parasite of porcelain crab Pachychelespubescens (Fig. 14C)	Aporobopyrusoviformis
–	Adult female head subtriangular in shape, anterolateral margins produced into small obtuse projections, eyes present; rudimentary coxal plates of pereomeres 3 and 4 only on longer side of body; branchial parasite of porcelain crabs Pachycheles spp. (Fig. 14B)	Aporobopyrusmuguensis
12	Adult female body oval to broadly oval, pereon and pleon subequal in width; branchial parasite of mud shrimps of genus Upogebia	13
–	Adult female body not oval, pleon tapering to much narrower than widest pereomeres	14
13	Adult female body broadly oval, almost as wide as long (L:W ratio ~ 1.2); head almost square, deeply embedded in pereomere 1, eyes absent; ventral surface of pleomeres covered by overlapping lanceolate lateral plates and uniramous uropods, middle region covered by similar sized biramous pleopods (Fig. 14E)	Orthionegriffenis
–	Adult female body oval, distinctly longer than wide (L:W ratio ~ 1.5); head slightly wider anteriorly than posteriorly, deeply embedded in pereomere 1, eyes present; ventral surface of pleomeres covered by numerous ridges and lanceolate biramous, marginally tuberculate pleopods (Fig. 14F)	Progebiophilusbruscai
14	Pleon of adult females composed of 5 medially fused pleomeres and pleotelson, the latter deeply arcuate and embedded in pleomere 5; head roughly triangular, separated from pereon by deep groove, eyes absent; branchial parasite of hippolytid shrimps Hippolytecaliforniensis and Thoralgicola (Fig. 15E)	Schizobopyrinastriata
–	Adult female body not as above; pleomeres distinctly separate, not medially fused; head with or without eyes	15
15	Head of adult female partially fused with pereomere 1 and separated by only short lateral notches; frontal margin of head slightly sinuated with anterolateral process usually on just short side of body, small eyes present; pleotelson entirely set within curves of pleomere 5; branchial parasite of snapping shrimps Alpheopsisequidactylus and Synalpheuslockingtoni (Fig. 15A)	Bopyrellacalmani
–	Female head distinctly separate and not fused with pereomere 1, eyes absent; pleotelson not completely set within curves of pleomere 5	16
16	Head of adult female squarish with distinct anterolateral horns and a small anteromedial indentation; pleon with 6 distinct pleomeres separated by deep lateral notches; pleopods 1–4 biramous (5th pair absent), uropods absent; branchial parasite of alpheid shrimp Automate sp. A (Fig. 15B)Endnote 9	Capitetragonia sp. A
–	Female head wider anteriorly than posteriorly, without anterolateral horns; pleon with 5 pleomeres not separated by deep notches and very small 6th segment, 5 pairs of biramous pleopods, and terminal pair of lanceolate uropods	17
17	Endopods of pleopods 1–5 much larger than exopods, elongate and pointed, surface rough with irregular rugae; coxal plates of pereomeres 5–7 not developed as lamellae; branchial parasite of hermit crabs of genus Pagurus (Fig. 15C)Endnote 10	Eremitionegiardi
–	Endopods of pleopods 1–5 only slightly larger than exopods, triangular or ovate, surface smooth; coxal plates of pereomeres 5–7 developed as lamellae; branchial parasite of squat lobsters Galacanthadiomedeae and Munidaquadrispina in the East Pacific (Fig. 15D)	Pseudionegalacanthae
18	Adult female body simply an egg sac, without evidence of segmentation; antennae and mouthparts absent; parasite on barnacles of genera Balanus and Chthamalus (Fig. 16C)	Hemioniscusbalani [Hemioniscidae]
–	Adult female body with weak evidence of segmentation visible dorsally or laterally; antennae and mouthparts present; parasitic on caridean shrimp of families Pasiphaeidae and Pandalidae	19 [Dajidae]
19	Adult female body typically elongate and symmetrical, but may be irregular with deeper, stouter body in some specimens; head separate, typically hemispherical, visible dorsally or ventrally; segmentation of pereon usually visible laterally by 4 coxal plates; pleonal region posteriorly projected as unsegmented conical prominence; parasite on carapace of pasiphaeid shrimp Pasiphaeapacifica (Fig. 16A)Endnote 11	Holophryxusalaskensis
–	Adult female body ovate, all regions fused and indistinct dorsally; posterior margin of pleon appears notched with row of triangularly shaped processes; parasite on carapace of pandalid shrimps Pantomusaffinis and Plesionikatrispinus (Fig. 16B)Endnote 12	Zonophryxus sp.