KEY TO THE FAMILIES OF HARPACTICOIDA

(amended from Lang, 1948)

1.	Commensal on whales.	Balaenophilidae ^a)
	Not commensal on whales.	2
2.	Body laterally compressed, as Fig. 4.	Tegastidae
	Body dorso-ventrally compressed, with the expanded epimera of the anterior abdominal segments enfolding the posterior abdomen and caudal furca, giving the body the shape of a wood-louse. (Figs. 5-6).	3
	Body of a different shape from either of above conditions.	4
3.	Body-shape as Fig. 5; without clearly seen chitin “skeleton”; P.1 as Fig. 22.	Porcellidiidae ^a)
	Body-shape as Fig. 6; a chitinous “skeleton” clearly visible; P .1 as Fig. 23.	Peltidiidae
4.	Exp. A.2 of at least 6 segments.	5
	Exp. A.2 of not more than 4 segments.	6
5.	Distal segment of Enp. P.2 much longer than the entire Exp.	Longipediidae ^a)
	Distal segment of Enp. P.2 shorter than the Exp.	Canuellidae
6.	Segment bearing the P.1 not fused to the cph.; Exp. A.2 of 1 segment with several setae; Mxp. lamelliform with several setae. Mosses and freshwaters.	Phyllognathopodidae ^a)
	Segment bearing the P.1 not fused to the cph.; Exp. A.2 of 2 segments; Mxp. not lamelliform. Freshwaters.	Chappuisiidae ^a)
	Segment bearing the P.1 only partially fused with the cph.; Exp. A.2 absent or represented by 1-2 setae only; Mxp. degenerate; Fresh and salt waters.	Darcythompsoniidae
	Segment bearing the P.1 completely fused with the cph.	7
7.	Mx2 as Figs. 13-15; body fusiform or vermiform; Benp. P.5 with only 2 setae (Benp. and Exp. of P.5 may be fused together but the parts are always recognizable) (Fig. 36).	Ectinosomatidae
	These characters not combined.	8
8.	P.1 as Fig. 24.	Harpacticidae
	P.1 as Fig. 25.	Clytemnestridae ^a)
	P.1 as Fig. 26 (Enp. may be 2 or 3 segments).	Tisbidae
	P.1 as Fig. 27.	Tachidiidae
	P.1 as Fig. 28 (Exp. can be 1 to 3 segments; 2nd Enp. segment may bear 1 claw or two long setae); Exp. A.2 present at least as a rudiment.	Laophontidae
	P.1 as Fig. 29; Body pyriform; mouth-organs degenerate.	Metidae
	Exp. P.1 absent or of 1 small segment; Enp. of 2 segments (Figs. 30-31).	Cylindropsyllidae
	P.1 not as any of the above, or, if similar to Fig. 28 then Exp. A.2 absent.	9
9.	Exp. P.1 of 3 segments, middle segment without a spine on the outer border.	10
	Exp. P .1 of 3 segments, middle segment with a spine on outer border or Exp. P.1 of less than 3 segments.	12
10.	Enp. P.2-P.4 of 1 segment; Exp. P.3 (M) modified; 2^nd segment Exp. P.1 without an inner seta.	Parastenocarididae ^a) (freshwater)
	Enp. P.2-P.4 of 1:1:2 segments respectively; Exp. P.3 (M) not modified; 2^nd segment Exp. P.1 without an inner seta.	Cylindropsyllidae
	Enp. P.2-P.4 of 2:1:2 segments respectively; Exp. P.3 (M) not modified; 2^nd segment Exp. P.1 with an inner seta.	Cylindropsyllidae
	Enp. P.2-P.4 each of 2 segments; Exp. P.3 (M) not modified; 2^nd segment Exp. P.1 with or without an inner seta.	11
11.	2^nd segment Exp. P.1 with an inner seta.	Ameiridae
	2^nd segment Exp. P.1 without an inner seta.	Cylindropsyllidae
12.	1^st segment Exp. P.1 with an inner seta; Mxp. not prehensile.	13
	These characters not combined.	14
13.	Exp. A.2 of 1 segment, with at most 2 setae.	Aegisthidae ^a)
	Exp. A.2 of 3-4 segments with several setae.	Cerviniidae
14.	Enp. P.4 at most 2 segments.	15
	Enp. P.4 of 3 segments.	31
15.	Exp. A.2 of 4 segments; Mxp. not prehensile; Enp. P.1-P.4 with 3:2:2:2 segments respectively.	Neobradyidae ^a)
	Exp. A.2 of 3 segments.	16
	Exp. A.2 at most 2 segments.	17
16.	Mxp. not prehensile; Enp. P.1-P.4 with 2:3:2:2 segments respectively.	Tisbidae
	Mxp. prehensile; Enp. P.1-P.4 each of 2 segments.	Diosaccidae
17.	Mxp. not prehensile; A.1 (F) of 5-6 segments with plumose setae, all segments serrated dorsally.	Tisbidae
	Mxp. not prehensile; remainder of above characters not combined.	18
	Mxp. prehensile.	20
18.	P.4 as Fig. 33 (Enp. may be 1 or 2 segments); P.5 a single small plate; A.1 (F) of not more than 7 segments.	Cylindropsyllidae
	These characters not combined.	19
19.	Distal segment Exp. P.2-P.4 with 3 spines on the outer border.	Louriniidae ^a)
	Distal segment Exp. P.2-P.4 with at most 2 setae and/or spines on the outer border.	Darcythompsoniidae
20.	Mxp. as Fig. 20.	Cylindropsyllidae
	Mxp. not as above.	21
21.	Exp. P.4 as Fig. 33 (Enp. may be 1 or 2 segments); P.5 a single plate.	Cylindropsyllidae
	These characters not combined.	22
22.	Mxp. as Fig. 19.	Paramesochridae
	Mxp. not as above.	23
23.	Labrum large and strongly prominent; Rostrum articulated with cph.; Cu.f. always distinctive in shape.	Tetragonicipitidae
	These characters not combined.	24
24.	Exp. A.2 absent; A.1 (F) at most 5 segments.	Ancorabolidae
	These characters not combined.	25
25.	All body segments sharply differentiated; Enp. P.1 not prehensile, at most of 2 segments.	Cletodidae
	These characters not combined.	26
26.	A.1 (F) of 4-5 segments; Enp. P.1 not prehensile.	Cletodidae
	These characters not combined.	27
27.	P.1 as Fig. 32.	Ameiridae
	P.1 not as above; basis of P.2-P.4 transversely prolongated.	Ameiridae
	P.1-P.4 not as either of above.	28
28.	A.2 with basis (Fig. 8).	Ameiridae
	A.2 with allobasis (Fig. 9).	29
29.	Rostrum large; P.5 as Figs. 37-38.	Diosaccidae
	Rostrum large; P.5 not as above; A.1 (F) of 4 segments; Exp. A.2 of 1 segment.	Canthocamptidae
	Not as either above.	30
30.	Enp. P.1 prehensile; Enp. P.2-P.3 of 3 segments.	Diosaccidae
	These characters not combined.	Canthocamptidae
31.	Cuticular lenses present.	Miraciidae ^a)
	No cuticular lenses.	32
32.	Body shape as Fig. 7.	Miraciidae ^a)
	Body shape not as above.	33
33.	A.2 with basis (Fig. 8); Exp. A.2 of 1 segment; Mx2 with at most 3 endites.	34
	These characters not combined.	38
34.	P.5 with Benp. and Exp. distinct.	35
	P.5 with Benp. and Exp. fused to form a single plate.	37
35.	Enp. P.1 of 2 segments, not prehensile.	Cletodidae
	Enp. P.1 of 3 segments.	36
36.	1^st segment Exp. P.1 with an inner seta.	Cletodidae
	1^st segment Exp. P.1 without an inner seta.	Ameiridae
37.	Distal segment Exp. P.2-P.4 each with at least 5 setae and/or spines.	Ameiridae
	Distal segment Exp. P.2-P.4 each with only 4 setae and/or spines.	Latiremidae ^a)
	Distal segment Exp. P.2-P.4 with 4:5:5 setae and/or spines respectively.	Cletodidae
38.	Mxp. well developed, not prehensile.	Tisbidae
	Mxp. not as above.	39
39.	Enp. P.1 not prehensile.	40
	Enp. P.1 prehensile.	43
40.	Exp. A.2 very small, of 1 segment with 2 setae at most.	41
	Exp. A.2 well developed, of 2-4 segments with more than 2 setae.	42a
41.	Enp. P.1 of 3 segments.	Cletodidae
	Enp. P.1 of 2 segments.	Diosaccidae
42a	Enp. P.1 of 2 segments.	Tachidiidae
	Enp. P.1 of 3 segments	42b
42b	Enp. P.1 of 3 short segments; 1^st segment shorter than the 2^nd and 3^rd, which are approximately equal in length; P.5 either a single plate or with the inner expansion of the Benp. well developed.	Tachidiidae
	Enp. P.1 of 3 segments; 1^st and 2^nd segments elongate, the 3^rd very short; Inner expansion of Benp. reduced (Fig. 39).	Tisbidae
43.	Enp. of Mxp. of at least 2 segments (Fig. 18) .	44
	Enp. of Mxp. of 1 segment only, the more distal segments not distinguishable from the terminal claw (Fig. 17).	45
44.	Inner expansion of Benp. P.5 well developed, with several setae.	Diosaccidae
	Inner expansion of Benp. P.5 not well developed, without setae.	Tisbidae
45.	Exp. P.1 with 1 or 2 segments only.	Thalestridae
	Exp. P.1 with 3 segments.	46
46.	At least one of the Enp. of P.2-P.4 of less than 3 segments.	Thalestridae
	Enp. P.2-P.4 of 3 segments.	47
47.	Distal segment of Enp. P.2-P.4:
	each with 5 setae and/or spines.	48
	each with 4 setae and/or spines.	49
	each with 3 setae and/or spines.	50
	with 5:6:5 setae and/or spines respectively.	51
	with 4:4-5:4-5 setae and/or spines respectively.	52
	with 4:6:5 setae and/or spines respectively.	53
	with a setation different from any of the above.	Ameiridae
48.	Enp. P.1 of 3 segments, the 1^st only slightly longer than the last two together.	Ameiridae
	Enp. P.1 of 2 or 3 segments, the 1^st very much longer than the remainder.	Thalestridae
49.	Enp. P.1 of 3 segments.	Ameiridae
	Enp. P.1 of 2 segments.	Thalestridae
50.	Exp. A.2 of 3 segments; P.5 a single plate; Enp. P.1 not prehensile.	Thalestridae
	Exp. A.2 of 2 segments; Benp. And Exp. P.5 distinct; Enp. P.1 prehensile.	Ameiridae
51.	A.2 with allobasis (Fig. 9) or if with a basis then the 2^nd segment of Enp. P.2-P.3 has two inner setae.	Thalestridae
	A.2 with basis (Fig. 8); 2nd segment of Enp. P.2-P.3 with 1 inner seta at most.	Ameiridae
52.	2^nd segment of Exp. P.1 elongate, much longer than either the 1^st or the 3^rd segment.	Parastenheliidae ^a)
	All segments of Exp. P.1 of approximately equal length.	Ameiridae
53.	2^nd segment of Exp. P.1 elongate, much longer than either the 1^st or the 3^rd segments; Exp. P.5 (F) a large foliaceous plate.	Thalestridae
	All segments of Exp. P.1 of approximately equal length.	Ameiridae

a) The following notes are relevant to these families.

1. Phyllognathopodidae and Chappuisiidae

Species of these families have never been found in marine or brackish waters. The Chappuisiidae contains only the genus Chappuisius; its two species are described in Lang (1948). The Phyllognathopodidae contains two genera: Phyllognathopus, which is described in Lang (1948), although several new species have been discovered subsequently, and Allophyllognathopus Kiefer, 1967, with a single species.

2. Parastenocarididae

An almost exclusively freshwater family with three genera. Parastenocaris is a large genus whose diagnosis is given by Lang (1948) along with descriptions of many species, although very many more have been discovered subsequently. Forficatocaris Jakobi, 1969 and Paraforficatocaris Jakobi, 1972 are the other genera.

Two species of Parastenocaris, P. phyllura and P. vicessima, have been recorded from brackish waters; descriptions are given by Lang (1948).

3. Aegisthidae, Clytemnestridae (by Boxshall, 1979) and Miraciidae

These families are found exclusively in the marine plankton. A key is given by Wells (1970).

4. Balaenophilidae

Contains the single species Balaenophilus unisetus which has been recoded only as a commensal on baleen whales.

5. Neobradyidae

Contains the single species Neobradya pectinifera.

6. Louriniidae

Contains two species only, Lourinia armata and L. nicobarica, which probably are synonymous.

7. Parastenheliidae

Contains the single genus Parastenhelia.

8. Porcellidiidae

Contains the single genus Porcellidium, of which the following species are not included in the catalogues of Lang and Bodin:

P. unicus Ummerkutty, 1970,

P. dilatatum Hicks, 1971,

P. erythrum Hicks, 1971,

P. planum Tiemann, 1977,

P. paniculiferum Tiemann, 1978,

P. hartmannorum Tiemann, 1978,

P. tapui Hicks & Webbe, 1983,

P. tristanense is redescribed by Hicks (1982a),

P. algoense Hicks, 1982a,

P. laurencium Hicks, 1982a,

P. ulvum Hicks, 1982a,

P. brevicaudatum redescribed by Humes & Ho (1969b)

9. Longipediidae (see Wells, 1981; Itô, 1981)

Contains the single genus Longipedia, about which the following information is relevant.

L. minor helgolandica Klie, 1949 is raised to species rank by Gonzalez & Bowman (1965).

L. pontica n.sp. of Apostolov (1969) is not L. pontica Kricagin, which Apostolov (1973a) considers a synonym of L. minor.

10. Latiremidae

The affinities of the family are obscure. It was erected by Bozic (1969) to accommodate a new genus and species, Latiremus eximus, but it would seem that the problematical genus Delamarella Chappuis, 1954a is closely related; Bozic does not discuss this possibility. Chappuis could not decide on the correct family for his genus and placed it as incertae sedis in the Order. No further discussion of the affinities of Delamarella has appeared in the literature to date. The most peculiar feature of Latiremus is the modified P.4 Exp. of the male, which characteristic is also shown in an almost identical manner in Delamarella and this genus is so very similar also in the P.1, P.5, caudal furca, mandible palp, setation of P.1-P.4 that there can be little doubt of their relationship. They may even be congeneric but until a thorough examination is possible it is best to consider them distinct. The species of the family are:

Latiremus eximius Bozic, 1969,

Delamarella arenicola Chappuis, 1954a,

D. karamani Petkovski, 1957,

D. galateae Cottarelli, 1971b.