Porcellidium fimbriatum Claus, 1863

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 : 82-87

publication ID	https://doi.org/ 10.3853/j.2201-4349.66.2014.1594
persistent identifier	https://treatment.plazi.org/id/03AF87A1-853E-FFB1-47F9-5AD5FD61D0EB
treatment provided by	Carolina
scientific name	Porcellidium fimbriatum Claus, 1863
status

Treatment

Fig. 9–12 View Figure 9 View Figure 10 View Figure 11 View Figure 12

Porcellidium fimbriatum Claus, 1863:140 , taf. xxii, fig. 1. P. fimbriatum .— Claus, 1889: 32, figs. VII 1–18, VIII 1–8

(redescription); Bocquet, 1948: 247–250; Harris &

Robertson, 1994: 301; HuYs et al., 1996: 308; Walker-

Smith, 2001: 656; Wells, 2007: 79. P. viride .— Lang, 1948: 420. P. lecanoides .—Norman & Scott, 1906: 182. Thyone viridis .—Vervoort, 1964: 119.

Type material. The description and illustrations Claus gave of P. fimbriatum (1863) are misleading for they do not show a single species specific character that would confirm the animal’s identity. It is possible that Claus was looking at mixed material because, as shown above, P. fimbriatum and P. viride may be found in the same sample. In 1889 Claus redescribed his P. fimbriatum giving eight or more species specific characters which should have cleared up any misunderstanding between the two species, but his synonymies show that he believed his animals were the same species as Brady’s P. “ fimbriatum ” which is known to be the female of P. viride . Moreover, P. lecanoides Claus, 1889 is a junior synonym for P. viride . In order to stabilize the taxonomy of Porcellidium fimbriatum in the apparent absence of a type specimen, a male with antennules extended to show species specific features has been selected as a NEOTYPE for Porcellidium fimbriatum Claus, 1863 .

Neotype designation. NEOTYPE adult male with antennules extended, to show coupling denticles, length 0.56 mm, P92561 deposited at the Australian Museum , SYdneY; collected from Laminaria saccharina, LW spring tide at Clachan , Seil Sound, Oban, Scotland (56°19'N 5°35'W), V. A. Harris, September 1997 GoogleMaps .

Material examined (specimens determined to be conspecific to the neotYpe): slide material in NHM ( Porcellidium 339), (see Appendix 1); specimens from Castle Heads, Dale Pembrokeshire, Wales (51°42'N 5°10'W) and Clachan, Seil Sound, Oban, Scotland (56°19'N 5°35'W), identified as P. fimbriatum from Claus (1889); specimens collected from Laminaria digitata at Clachan, Scotland, AM P89055 (15 ♀♀, 8 ♂♂ + 3 coupled ♂♂, V. A. Harris, 1997). Other specimens (60 ♀♀, 30 ♂♂ + 8 coupled ♂♂, V. A. Harris, 1997) and slide mounted dissections have been deposited at NHM, London. The following description is based on the neotype and material examined.

Diagnosis. No finelY plumulose setae on male antennule segment 2, first seta on segment 2 not longer than remaining setae, short blade-like ventral process on segment 3, three coupling denticles on segment 4 (proximal with serrated edge, two distal denticles small, botryoidal, no denticulate pad present), dactYlus short (<1/2 length of segment 4) segment 5 not expanded, segment 6 clearly visible, not fused to segment 5; no U-shaped wrinkles on ventral surface of male rostrum; female caudal ramus long, rectangular (l/w = 2.7–2.8), terminal setae T1–T4 all conspicuously pinnate, gap between T3 and T4 <1/2 width of ramus, Hicks’ index for β seta 25%; female genital double-somite with deep cleft or scar between anterior and posterior lobes (clear triangular area absent), no sensilla on border of posterior lobe; male genital segment with two rows of three dorsal sensilla; ventral surface of male and female cephalosome with fine lines (wrinkles); male P5 exopod trapezoid, apical angle 50°. Spermatophore elongate, ephemeral on female.

Biometric data. Females (N = 43): maximum length (Lmax) 0.77 mm, body length (Lurs) 0.76 mm (range 0.73–0.79 mm); cephalosome width 0.45 mm (range 0.43–0.47 mm); rostrum (R) 0.095 mm; genital double-somite width 0.32 mm, length 0.27 mm; caudal ramus length 0.14 mm, width 0.05 mm.

Ratios: Lurs / W 1.7; W/ R 4.7 ; genital double-somite width 70% of cephalosome width, w/l 1.2; caudal ramus 18% of Lurs, l/ w 2.8, Hicks’ index for β seta 25 %.

Males (N = 25): maximum length (Lmax) 0.56 mm, body length (Lurs) 0.50 mm; cephalosome width (W) 0.38 mm; spermatophore 0.15 × 0.03 mm; antennule fullY extended 0.135 mm.

Ratios: Lmax / W 1.47, Lurs / W 1.32; antennule 35% of cephalosome width, segment 2 30%, segment 3+4 42% and dactYlus 15% of antennule length; spermatophore 27% of Lurs.

Description. Adult females ( Fig. 9A View Figure 9 ; Plate 1C, p. 67): colourless or pale yellow with broad band of deep violet or dark blue down middle of back, including genital doublesomite and caudal rami. Body outline elongate oval, sides of body almost parallel, rostrum narrow (W/R = 4.7). Dorsal surface of cephalosome, metasome and genital double-somite ornamented with dorsal pits (5–6 µm in diameter), ventral surface of cephalosome with fine wrinkles (see Fig. 12A View Figure 12 ). HYaline border 8 µm wide. No patch of setules on labrum. Genital double-somite ( Fig. 9H View Figure 9 ) relativelY long (w/l = 1.2), posterior arch deep, slight notch or indentation between anterior and posterior lobes with transparent scar (scar appears as deep cleft when compressed with cover glass, cf Claus’ 1889 illustration). No sensilla on edge of posterior lobe ( Fig. 9E View Figure 9 ), border setules on posterior lobe longer than those on anterior lobe. Genital opening ( Fig. 9G View Figure 9 ). Caudal rami ( Fig. 9C, D View Figure 9 ) long (18% of body length), rectangular (l/w = 2.8), almost completely enclosed in arch of genital double-somite, dorsal surface with network of fine ridges but no pits. Medial edge straight, slightly bevelled distally, lateral edge slightly convex, both edges with setules posteriorly. Beta seta about 3/4 down ramus (Hicks’ index = 25%), terminal setae T1–T4 conspicuously pinnate, equal in length, T2 and T3 very close on slight prominence midway between T1 and T4, distance between T3 and T4 equal or less than 1/4 width of ramus, verY fine terminal fringe of setules between T3 and T4. No finelY plumulose setae on segment 2 of antennule. Structure and setation of mouthparts and ambulatory limbs typical of family. Antenna ( Fig. 10C View Figure 10 ). Mandible with small group of setules on anterior lobe of palp ( Fig. 10B View Figure 10 ). Segment 1 of P1 endopod elongate triangular, narrow (l/w =1.5), coxa with internal seta ( Fig. 10A View Figure 10 inset). Serrulate spinous seta on segment 2 of P3 endopod ( Fig. 11C View Figure 11 ) shorter than endopod (0.8:1), large serrate spinous seta on terminal segment considerably longer than endopod (1.7:1). P4 with internal serrulate spinous seta on segments 2 and 3 ( Fig. 11A View Figure 11 ). P5 ( Fig. 10F, G View Figure 10 ), exopod broadly lanceolate, with dorsal pits, one sub-terminal dorsal seta and two apical setae. Females carry 12– 14 eggs per brood.

Adult males ( Fig. 9B View Figure 9 ; Plate 1E, p. 67). Colouration as for female except that in a few specimens the violet blue colour is absent from posterior region of bodY. HeavilY sclerotized parts of the antennules and antennule sockets are orange on most males. Cephalosome truncated, anterior edge straight (not convex in mid-line), shoulders rounded. Rostrum not wrinkled ventrallY, ventral surface of cephalosome with fine wrinkles ( Fig. 12A View Figure 12 ). Dorsal surface with pits as for female. Genital somite with dorsal pits, lateral row of three dorsal sensilla on each side ( Fig. 11E View Figure 11 ). Caudal rami slightly longer than wide (l/w = 1.1), dorsal surface with reticulate markings, medial edge straight, lateral edge convex ( Fig. 9F View Figure 9 ). Beta seta 2/3 down ramus, terminal setae conspicuouslY pinnate, space between T3 and T4 wider than in female (almost 1/2 width of ramus) with fringe of fine setules. Antennule ( Figs 12D, F View Figure 12 ) with first seta on segment 2 not longer than 1.5 times length of second seta, segment 3 with short blade-like ventral process, segment 4 with three coupling denticles (proximal with serrated edge, middle and distal denticles small with botryoidal surface, no denticulate pad), dactylus very short, cYlindrical (<1/3 length of segments 3+4), distinctlY two segmented, without pronounced terminal hook. P2 endopod with two plumose terminal setae ( Fig. 11B View Figure 11 ), Setae on segments 2 and 3 of P4 endopod all plumose. P5 exopod with dorsal pits ( Fig. 12B View Figure 12 ), ventral setules at base of each terminal seta ( Fig. 12C View Figure 12 ), apical angle of P5 50°.

Remarks. Claus did not explain why he called this species fimbriatum , but he must have been impressed by the marked difference between the narrow pointed caudal rami of his Porcellidium tenuicauda and the posterior border fringed with bristles of his new 1863 species, (L. fimbriatum = separated into shreds or filaments, fringed). Claus redescribed the species in 1889 showing several species specific characters that allowed animals from Scotland to be identified as Porcellidium fimbriatum . The species is commonly found with P.viride on Laminaria in samples from Scotland.

Collection data. Porcellidium fimbriatum has been collected from the following algae. Laminaria sp., Plymouth, Devonshire , 1970. Alaria esculenta and Gigartina stellata at Skokholm Island , Pembrokeshire, 1970. Hymanthalia elongata at Great Castle Rocks , Dale , Pembrokeshire, Wales, V. A. Harris 1970, 1974. Chondrus crispus at Clachan, Seil Sound, Oban Scotland ES 2.9/74, 18 ♀♀, 25 ♂♂ and ES18b.11/74, 38 ♀♀, 5 ♂♂ + 13 ♂♂ coupled to juveniles; C. crispus and G. stellata ES 18a.11.74, 72 ♀♀, 28 ♂♂; Lithothamnion encrusted stones and boulders ES14.9/74, 3 ♀♀, 1 ♂; Laminaria saccharina ES 17.9/74, 7 ♀♀, 1 ♂; C. crispus and L. saccharina ES 20.9/97, 76 ♀♀, 16 ♂♂ + 11 ♂♂ coupled with juveniles; Laminaria digitata ES 19.9/97, 5 ♀♀, 1 ♂, V. A. Harris 1970, 1974, 1987, 1997 .