1	Eyes present	2
–	Eyes absent	36
2	Body (except head) covered with large, jointed-appearing spines; uropods very long if not broken off, with basal segments and rami each ca. as long as width of pleotelson (Fig. 31A)	Acanthomunnatannerensis [Dendrotionidae]
–	Body and uropods not as above	3
3	Eyes sessile, situated dorsolaterally on head but not reaching lateral margins; pleotelson subequal in width to cephalon and most pereonites	4
–	Eyes situated laterally on head, bulging outward on short to elongated ocular lobes or peduncle-like projections; pleotelson distinctly narrower than cephalon and widest pereonites	24
4	Head with rounded anterolateral margins and prominent rounded median lobe between antennae; body widest at ca. pereonite 6; adult body length < 3 mm; commensal on or in burrows of sphaeromatid Sphaeromaquoianum in bays and estuaries (Fig. 31B)	Iaiscalifornica [Janiridae, in part]
–	Head not as above; body lateral margins parallel or gently convex and slightly widest around mid-pereon; maximum adult length varies between ~ 1.3–7.3 mm	5
5	Body elongated and unpigmented, lateral margins parallel and covered with long simple setae; head with acute anterolateral angles and lightly pigmented eyes; pleotelson shield-like with small posterolateral spines; male pereopod 1 strongly subchelate with thick projection on inferior margin of propodus, and many long simple setae on dactylus, propodus, carpus, and merus (Fig. 31C)	Stenetrium sp. A [Stenetriidae]
–	Body, head, and male pereopod 1 not as above	6
6	Uropods short, inserted in subterminal excavations of pleotelson and not extending much beyond its posterior margin; both antennules and antennae small, flagella lacking or rudimentary; peduncle articles of antennae dilated	7 [Joeropsididae]
–	Uropods well-developed, extending well beyond posterior margin of pleotelson; both antennules and antennae relatively long with multiarticulate flagella, although flagella often broken off in preserved specimens; peduncle articles of antennae not dilated	11 [Janiridae, in part]
7	Body without pigment, covered with numerous fine simple setae	8
–	Body typically pigmented, not covered with fine setae	9
8	Body elongated and parallel-sided (L:W ratio ~ 4.3); head with distinct indentation on lateral margins below eyes; basal article of antennules with large, outwardly produced distolateral projection bearing ~ 6 sharp, flat spines curving toward article 2; pleotelson lateral margins with 7 large posteriorly curved spines, rest of body with small denticulations on lateral margins (Fig. 32A)	Joeropsis concava
–	Body broad and laterally curved (L:W ratio ~ 2.6); margins of head produced forming large lateral plate, with ~ 9 anteriorly curved spines, eyes not reaching lateral margins; basal article of antennules with small distolateral process bearing several lateral curving flat spines; pleotelson with 8 posteriorly curved spines (Fig. 32E)	Joeropsis sp. A
9	Lateral margins of pleotelson without spines; body banded in appearance, with dark brown pigment typically covering head, pereonites 2–4 and 7, and pleotelson; maxillipedal palp article 2 not produced medially; anterior margin of frontal lamina entire, without fringe of small scales (Fig. 32D)	Joeropsislobata
–	Lateral margins of pleotelson with 3–7 spines; body typically with diffuse pigment, which may be most pronounced on head and pereonite 4; maxillipedal palp article 2 produced medially; anterior margin of frontal lamina with fringe of small scales	10
10	Lateral margins of pleotelson with 5–7 spines; head typically heavily pigmented, pereon and pleon lightly pigmented or without pigments (Fig. 32B)	Joeropsisdubiadubia
–	Lateral margins of pleotelson with 2 or 3 spines; head and pereonite 4 both typically heavily pigmented but compare pigment pattern of head with that of J.dubiadubia above (Fig. 32C)	Joeropsisdubiapaucispinis
11	Pereopod 1 with conspicuous serrations or denticles on proximal third of inferior margin of propodus; maxillipedal palp articles 1–3 as wide as endite	12
–	Pereopod 1 without denticles on proximal third of inferior margin of propodus; maxillipedal palp articles 2 and 3 much wider than endite	19
12	Pleotelson with distinct distolateral angles or spines; head with pointed anterolateral margins and distinct rostrum	13
–	Pleotelson without distolateral spines, posterolateral margins rounded; head with pointed or rounded anterolateral margins, with or without rostrum	16
13	Adults with acutely pointed rostrum extending well beyond anterior limits of anterolateral margins of head; body completely devoid of pigment (Fig. 33F)	Janiralata sp. B
–	Adults with rostrum not extending anteriorly beyond anterolateral margins of head; body pigmented	14
14	Head with acute rostral point; posterior margin of pleotelson concave laterally with convex median lobe that does not extend beyond posterior limits of distolateral spines; species lives commensally on sun stars (Solaster spp.), and its occurrence in southern California is questionable (Fig. 33D)	Janiralatasolasteri
–	Head with obtuse rostral point; posterior margin of pleotelson with convex lateral areas and obtusely rounded median point that extends posteriorly distinctly beyond limits of distolateral spines	15
15	Body covered with diffuse, anastomosing chromatophores, with pigment extending into region anterior to eyes (Fig. 33E)	Janiralata sp. A
–	Body covered with dense, non-anastomosing chromatophores that are absent from region anterior to eyes (Fig. 33B)	Janiralataoccidentalis
16	Head with angular anterolateral margins and short, acute median lobe or slightly rounded median point; eyes medium to large, dorsal, clearly separated from lateral margins of head; body relatively short and broad (L:W ratio < 2.5); pleotelson nearly 2 × as wide as long	17
–	Head with rounded anterolateral margins, without distinct median lobe or rostrum; eyes large, almost touching lateral margins of head; body long and narrow (L:W ratio > 3.0); pleotelson ca. as wide as long	18
17	Dorsal surface with numerous black chromatophores; pereonites 1–3 with distinct lateral lobes or lappets, each pair separated by narrow V-shaped slit; all lateral margins with conspicuous setal fringe; posterolateral margins of pereonites 5–7 angular; pereonite 5 not shorter medially than other pereonites (Fig. 33A)	Janiralatadavisi
–	Dorsal surface without pigment, but with many fine setae; pereonites 2 and 3 with short anterior lappets and indistinct posterior lappets; lateral margins without conspicuous setal fringe; posterolateral margins of pereonites 5–7 rounded; pereonite 5 distinctly shorter medially than other pereonites (Fig. 33G)	Janiralata sp. C
18	Body whitish, without distinct chromatophores; pereopod 1 propodus with ~ 12 or 13 denticles on proximoventral border (Fig. 33C)Endnote 24	Janiralatarajata
–	Body pigmented with numerous dense chromatophores; pereopod 1 propodus with ~ 18 denticles on proximoventral border (Fig. 33H)Endnote 24	Janiralata sp. D
19	Lateral margins of pleotelson with spine-like serrations	20
–	Lateral margins of pleotelson without serrations, although setae may be present	21
20	Pleotelson with 4–7 spine-like serrations on each side (Fig. 34A)	Ianiropsisanaloga
–	Pleotelson with 3 spine-like serrations on each side (Fig. 34F)	Ianiropsistridens
21	Pleotelson with distinct posterolateral angles extended beyond uropodal insertions (Fig. 34B)	Ianiropsisderjugini
–	Pleotelson without posterolateral angles, posterior margins rounded	22
22	Uropods relatively short, not exceeding half-length of pleotelson; frontal margin of head truncate (Fig. 34D)	Ianiropsisminuta
–	Uropods much longer than half-length of pleotelson; frontal margin of head with short pointed or blunt medial lobe	23
23	Uropods very long, exceeding length of pleotelson; lateral apices of male pleopod 1 bifurcate (Fig. 34E)	Ianiropsismontereyensis
–	Uropods not exceeding length of pleotelson; lateral apices of male pleopod 1 not bifurcate (Fig. 34C)	Ianiropsiskincaidi
24	Pereonites 1–3, 5 and 6 with long, finger-like lateral processes, each with 1 or 2 terminal setae; pleotelson bulbous anteriorly, then tapers posteriorly to a narrow truncate end; uropods inserted dorsolaterally on anterior half of pleotelson, each uropod ca. as long as pleotelson; eyes tiny, each composed of two lenses at tip of very long and thin lateral peduncle or lobe (Fig. 35E)Endnote 25	Pleurocope sp. A [Pleurocopidae]
–	Pereonites, pleotelson and uropods not as above; eyes situated at tips of short to elongated ocular lobes	25
25	Antennules and antennae both long, subequal in length; frontal margin of head broadly rounded	26 [Paramunnidae, in part]
–	Antennae > 2 × longer than antennules; frontal margin of head broadly truncate, with or without medial concavity	29 [Munnidae]
26	Pereonites 1–3 with dorsal posterolateral setal tufts; pleotelson as wide or wider than pereonite 7, lateral margins of pleotelson serrate or denticulate anterior to uropodal insertions, denticulations with embedded compound setae in cusps (Fig. 35B)	Boreosignum sp. A
–	Pereonites without dorsal setal tufts; pleotelson narrower than pereonite 7, lateral margins convex without lateral serrations or denticulations	27
27	Body broadly ovate with pereonites 2 and 3 distinctly wider than pereonites 4 and 5 (body L:W ratio ~ 1.6); head deeply immersed in pereon with pereonite 1 much longer (male) or subequal (female) in length to pereonite 2; eyestalk (ocular lobe) much longer than article 1 of antennules; coxae visible in dorsal view only on pereonites 5–7 (Fig. 35A)	Austrosignumlatum
–	Body narrower than above with pereonites 2–5 subequal in width (body L:W ratio > 2.0); head not deeply immersed in pereon, with pereonite 1 shorter than pereonite 2 in both sexes; ocular lobes much shorter than article 1 of antennules; coxae visible in dorsal view on at least pereonites 2–7	28
28	Article 1 of antennules shorter than article 2; pereopod 2 in males with robust subtriangular projection on distoventral corner of basis, and proximal projection on ischium; pereopod 2 ventral margins of propodi with short robust setae (Fig. 35C)Endnote 26	Munnogoniumerratum
–	Article 1 of antennules subequal in length or longer than article 2; pereopod 2 in males not as above, without distinct projections on basis and ischium; pereopod 2 ventral margins of propodi with simple setae only (Fig. 35D)Endnote 26	Munnogoniumtillerae
29	Pleotelson with 4–6 spines or serrations on ventrolateral margins; male pleopod 1 apically pointed (Fig. 36H)	Uromunnaubiquita
–	Pleotelson without spines on lateral margins; male pleopod 1 with apices laterally expanded	30
30	Pleotelson with concave posterolateral margins; posterior border of pereonite 7 convex (Fig. 36D)	Munnamagnifica
–	Posterolateral margins of pleotelson not concave, although small indentations may be present around uropodal insertions; pereonite 7 with deeply concave posterior border wrapping around anterior portion of pleotelson	31
31	Uropods with large acute spine-like protuberances on distal margins; pleotelson posterior margin without subanal channel or shelf visible in dorsal view	32
–	Uropods without spine-like protuberances on distal margins; pleotelson with or without subanal shelf visible in dorsal view	33
32	Lateral margins of pleotelson with 2 or 3 backwards-curved robust sensory setae on each side; pleotelson broad medially, nearly as wide as long (Fig. 36F)	Munnastephenseni
–	Lateral margins of pleotelson without robust sensory setae; pleotelson narrow, much longer than wide (Fig. 36A)	Munnachromatocephala
33	Frontal margin of head with ~ 8 stout, 2-pointed spines; lateral margins of pereonites 1–6 with stout spines; pleotelson without subanal shelf (Fig. 36E)	Munnaspinifrons
–	Margins of head and pereonites without spines, although setae may be present; pleotelson with subanal shelf visible in dorsal view	34
34	Eyes small, occupying ca. half of short ocular lobes; body surfaces smooth, not covered with setae; uropods tiny, hidden within short, broad subanal shelf (Fig. 36C)	Munnahalei
–	Eyes large, occupying most of prominent ocular lobes; all dorsal surfaces covered with fine simple setae; uropods larger and clearly visible, not hidden by subanal shelf	35
35	Subanal shelf short and broad, reaching but not obscuring uropods; male pleopod 1 with large sensillate setae on ventral surface (Fig. 36B)	Munnafernaldi
–	Subanal shelf elongated posteriorly, but no wider than anus and not reaching or extending under uropods; male pleopod 1 with short simple setae on ventral surface (Fig. 36G)	Munna sp. A
36	Surface of body covered with many small spines and fewer large spines; dorsal surface of pleotelson with pair of large stout posterior protuberances, each with 3 large distal spines (Fig. 37)	Haplomunnacaeca [Haplomunnidae]
–	Surface of body and pleotelson not as above	37
37	Pereopods 5–7 expanded and natatory, with enlarged, paddle-like carpi and propodi; posterior body arranged as distinctive natasome, consisting of partially or completely fused pereonites 5–7 and the pleotelson	38 [Munnopsidae]
–	Pereopods 5–7 without enlarged, paddle-like carpi and propodi; posterior part of body without distinct natasome	43
38	Head with bilobed or pointed rostrum projecting anteriorly between antennules	39
–	Head without rostrum extending between antennules	40
39	Head with broad, indented (bilobed) rostrum; natasome flattened, tapering; pereonites 5 and 6 fused dorsally; pereonite 7 smaller and narrower than pereonites 5 and 6 (Fig. 38A)	Belonectes sp. A
–	Head with narrow, roundly pointed rostrum, not bilobed; natasome robust and deep; pereonites 5 and 6 not fused dorsally; pereonite 7 larger than pereonites 5 and 6 (Fig. 38B)	Eurycopecaliforniensis
40	Natasome not triangular, pleotelson inflated dorsally with relatively straight lateral margins; pereonites 5–7 subequal in size; uropodal protopod small, tubular	41
–	Natasome triangular, lateral margins of pleotelson taper to pointed apex; pereonite 7 distinctly narrower than pereonites 5 and 6; uropodal protopod large, flattened	42
41	Head subequal in width to pereonite 1; small species, with body length of adults < 2 mm (Fig. 38E)	Munnopsurus sp. A
–	Head very large, distinctly broader than pereonite 1; much larger species than above, with body length of adults reaching 7 mm (Fig. 38F)	Munnopsurus sp. B
42	Anterior margins of pereonites 1–4 with large pedestal setae (Fig. 38C)	Ilyarachnaacarina
–	Anterior margins of pereonites 1–4 with small, non-pedestal setae (Fig. 38D)	Ilyarachnaprofunda
43	Body with conspicuous setal fringe on lateral margins; head trilobate anteriorly; pleotelson wider than long with concave posterior margins at uropodal insertions and blunt median apex; basal article of antennules greatly expanded; article 3 of antennae with elongate, setiferous scale; small intertidal isopods that live in burrows in wood excavated by limnoriid isopods (Fig. 39A)	Caecijaerahorvathi [Janiridae, in part]
–	Body and habitat not as above	44
44	Body greatly elongated, > 6 × longer than wide; lateral margins generally parallel with head, pereonal, and pleonal segments subequal in width	45
–	Body not as long as above, ≤ 4.5 × longer than wide; lateral margins distinctly not parallel	47
45	Antennae with strong scale on peduncular article 3; uropods long and distinct, protopod subequal in length to pleotelson and half as wide, sides parallel until pinching off slightly towards distal medial tip; uropodal endopod ca. one-third length of protopod and attached subapically; uropodal exopod ca. half-length of endopod and attached more laterally near where protopod begins to curve inwards (Fig. 39C)Endnote 27	Microcharon sp. A [Lepidocharontidae]
–	Antennae without scale on peduncle; uropods styliform, not as above (Fig. 39B) [Janiridae, in part]	46
46	Integument of body with complete and prominent scaling; peduncular article 2 of antennules with ≥ 3 strong longitudinal ridges; mandibles whitish, not appearing sclerotized; setal comb present on posteroventral margin of basis of anterior pereopodsEndnote 28	Caecianiropsis sp. LA1
–	Body with very light and intermittent scaling; peduncle of antennules without longitudinal ridges; mandibles brownish, heavily sclerotized; setal comb absent on posteroventral margins of basis of anterior pereopodsEndnote 28	Caecianiropsis sp. LA2
47	Pereonite 7 fused dorsally with pleotelson; body widest at posterior third of pleotelson; posterior margins of pleotelson with large bilobed medial extension and large tooth on each lateral edge (Fig. 40D)	Nannonisconuslatipleonus [Nannoniscidae]
–	All pereonites dorsally free; body widest at anterior half of pereon; pleotelson not as above	48
48	Body long and narrow (L:W ratio ~ 4.5); pereonites 1–3 only slightly wider than head and pleotelson	49 [Desmosomatidae]
–	Body short and broad (L:W ratio ≤ 2.0); pereonite 1 and usually pereonites 2–6 much wider than head and pleotelson	51 [Paramunnidae, in part]
49	Pereonite 1 distinctly larger than pereonite 2, with large ventral median spine; posteriorly curving ventral median spines also present on pereonites 3 and 7; pleotelson posteriorly rounded, with large subdistal ventrolateral spines (Fig. 40C)	Prochelator sp. A
–	Pereonite 1 subequal or smaller than pereonite 2; ventral median spines absent on all pereonites	50
50	Pereonite 1 subequal to pereonite 2; head with anterolateral spines; pleotelson with posterolateral spines or angles and a rounded posterior medial border; uropods biramous (Fig. 40B)	Momedossasymmetrica
–	Pereonite 1 smaller than pereonite 2; head without anterolateral spines; pleotelson without posterolateral spines; uropods uniramous, lacking exopods (Fig. 40A)	Desmosoma sp. A
51	Lateral margins of pleotelson serrate with numerous denticulations or spines; coxae of pereonites not visible dorsally	52
–	Lateral margins of pleotelson smooth, without denticulations or spines; coxae visible dorsally on pereonites 2–7, most or all with single large projecting spine	54
52	Anterior margin of head broadly quadrate with rounded anterolateral angles; lateral margins of pereonites heavily denticulate; pleotelson ca. as wide as long, lateral margins completely serrate; uropods inserted on posterolateral margins of pleotelson (Fig. 41A)	Paramunnaquadratifrons
–	Anterior margin of head with strongly produced and rounded anterior margin; lateral margins of pereonites with or without denticulations or spines; uropods inserted slightly dorsally on pleotelson	53
53	Head with 2 granulate tubercles above antennal bases; body widest at pereonite 1; lateral margins of pereonites serrate, anterior-most tooth enlarged and pointed forward on pereonites 1–3; pleotelson dentate along basal two-thirds of lateral margins, with 2 strong teeth located on rounded end where uropods would typically be inserted (Fig. 41B)	Paramunna sp. A
–	Head without granulate tubercles; body widest at pereonites 2 and 3; lateral margins of pereonites without denticulations or spines; pleotelson with serrated lateral margins, although the details are undocumentedEndnote 29	Paramunna sp. SD1
54	Basal articles of antennules with large curved anterolateral projections; body surface rough with apparent microscales; projecting spine on each coxa of pereonite 7 typically large and conspicuous (Fig. 41D)	Pleurogonium sp. A
–	Antennules without anterolateral projections on basal articles; surface of body smooth to slightly scaled; coxal spines of pereonite 7 reduced or absent (Fig. 41C)	Pleurogoniumcaliforniense