Porcellidium, Claus, 1860

Harris, Vernon A., 2014, Porcellidiidae of Australia (Harpacticoida, Copepoda). I. A Reassessment of the European Species of Porcellidium, Records of the Australian Museum 66 (2), pp. 63-110 : 66

Key to the species of Porcellidium

The antennules of male porcellidiids provide numerous species specific characters, consequentlY anY

male animal, for which the antennule has been described in detail, can be identified with a high degree of

certaintY. In marked contrast, verY few species specific characters have been found on female members

of the genus Porcellidium , consequently the females of less than half of the 20 recognized species can

be identified. This is because female characters are based upon shape, position, size or number of bodY

parts which will vary within a species and their measurements or ratios may overlap with other species.

The following key will rely heavily on characters of the male antennule which must be viewed from

the ventral side in the fully extended position (see Methods and nomenclature). Female ratios are given

to help confirm the identitY of the female animals. [Abbreviations: CR caudal ramus; GDS genital double-

somite; L length of animal; H.I. Hicks’ index for α or β setae; * see Hicks, 1982:64].

1 Male antennule with ventral process or “blade” on segment 3 (see Fig. 12D, F ) ........................................................................................................................ 2

—— Male antennule with “peg” or swollen knob on segment 3 (see Fig. 7F ) ............................................................................................................................... 3

—— No blade, peg or knob on segment 3 of male antennule ........................................................... 4

2 Ventral process short (1/4 length of segments 3+4), coupling denticle 1 on segment 4 flat with serrated edge, denticles 2 and 3 very small, botryoidal, segment 6 distinct (not fused with segment 5). Ventral surface of male and female cephalosome wrinkled ( Fig. 12A ). Female GDS with deep cleft between anterior and posterior lobe. Body length male 0.56 mm, female 0.77 mm, CR/L = 18%, CR l/w = 2.8, H.I. for β = 25%, setae T1–T4 pinnate. Colourless with broad band of dark blue down middle of back. Europe. (Plate 1C,E, p. 67) ............................................... P. fimbriatum ( Claus, 1863)

—— Ventral blade almost as long as segments 3+4, segment 3 with spine ventral to δ seta, denticle 1 on segment 4 comb-like, 2 and 3 serrate, segment 5 hooked, fused with 6. Body length male 0.55 mm, female 0.71 mm, CR/L = 7%, CR l/w = 1.2, H.I. for β = 20%. Colour Yellow with broad red dorsal stripe. Australia. (Plate 2B, p. 69) ............................................ P. pulchrum Harris & Robertson, 1994

Figures

Figure 7. Porcellidium viride (Philippi, 1840). Male: (A) detail of antennule coupling denticles; (B, C) P5 (ventral); (D) maxilla; (F, G) antennule (* peg or ventral process). Female: (E) showing extent of colour pattern of specimens from Loch HYne, Ireland. Scale bar: A = 0.06 mm. B, D, F, G = 0.08 mm.

Figure 12.Porcellidium fimbriatum Claus, 1863. Male:(A) rostrum and shoulder (ventral); (B, C) P5 (dorsal, ventral); (D, E, F) antennule (* ventral process). Scale bar:A, B, D, E = 0.08 mm. F = 0.06 mm.