Porcellidium roscoffensis (Bocquet) Harris, 2014

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 : 87-92

publication ID	https://doi.org/ 10.3853/j.2201-4349.66.2014.1594
persistent identifier	https://treatment.plazi.org/id/03AF87A1-8533-FFB6-446D-5AD5FC08D463
treatment provided by	Carolina
scientific name	Porcellidium roscoffensis (Bocquet)
status	comb. nov.

Treatment

Porcellidium roscoffensis (Bocquet) comb. nov.

Figs 13–16 View Figure 13 View Figure 14 View Figure 15 View Figure 16

Porcellidium lecanoides var. roscoffensis Bocquet, 1948: 250 , fig. IX.

P. lecanoides .—HuYs, et al. (1996): 308; Wells (2007): 79.

P. viride .— Bodin (1997):64.

Material examined. Specimens collected from mixed seaweeds, Castle Head, Dale, Pembrokeshire, Wales (3 ♀♀, 2 ♂♂) (51°42'N 50°10'W), V. A. Harris, 1970, 1974. Three slide-mounted dissections deposited in NHM, London GoogleMaps .

The following account is based on Bocquet’s (1948) descriptions of the caudal ramus and genital double-somite of P. lecanoides var. roscoffensis .

Diagnosis. Male antennule with knob or peg-like ventral process on segment 3, large proximal pad of fine denticles on segment 4, distal denticle with fine comb-like edge, dactYlus not broad, concave on one side, hooked terminally, segment 6 inconspicuous, fused to segment 5; ventral surface of male rostrum with U-shaped ridges or wrinkles; indentation (without border setules) marks boundary between anterior and posterior lobes of female genital double-somite, posterior lobe with two sensilla at edge; dorsal surface of male genital somite with five sensilla on each side; dorsal surface of female caudal ramus with pits, β seta close to γ seta.

Biometric data. Females (N = 1): body length (Lurs) 0.85 mm; cephalosome width (W) 0.60 mm; rostrum width (R) 0.15 mm; genital double-somite width 0.39 mm, length 0.28 mm; caudal ramus length 0.12 mm, width 0.05 mm.

Ratios: Lurs / W 1.42; W/ R 4.0; genital double-somite width 65% of cephalosome width, w/l 1.4; caudal ramus 14% of Lurs, l/ w 2.4, Hicks’ index for β seta 16 %.

Males (N = 1): body length Lurs 0.70 mm; bodY width 0.51 mm.

Ratios: Lurs / W 1.4; caudal ramus l/ w 0.8; antennule 46% of cephalosome width, segments 3+4 40%, and dactYlus 32% of antennule length.

Description. Adult females ( Fig. 13A View Figure 13 ): colour (see under Remarks). Anterior of cephalosome broadly rounded, rostrum prominent. Dorsal surface ornamented with circular pits 3 µm diameter, no obvious ridges but numerous pit and collared sensilla present on cephalosome, metasome and genital double-somite (see Fig. 13D View Figure 13 ). Ventral surface of cephalosome smooth, but ventral surface of rostrum has transverse ridges or wrinkles. HYaline border without striations, 12 µm wide. Labrum without ridge plates or setules. Genital double-somite ( Fig. 13D View Figure 13 ) broad, semicircular in outline, slight lateral notch without setules at that point, two small sensilla at edge of posterior lobe ( Fig. 13E View Figure 13 ), posterior arch deep, encloses most of the caudal rami. Genital opening ( Fig. 13F View Figure 13 ). Caudal ramus ( Fig. 13C View Figure 13 ) rectangular, dorsal surface ornamented with small pits, medial edge straight, medial corner slightly bevelled, lateral edge slightly convex. Terminal setae pinnate, T1 and γ setae recessed at lateral corner, β seta close to γ and posterior edge of ramus, T2 and T3 very close, T4 at medial corner, gap between T3 and T4 less than 1/2 width of ramus, fringed with fine setules. No finelY plumulose setae on segment 2 of antennule, first seta on segment 2 less than 11/2 times length of setae 2 or 3. Structure and setation of mouthparts and ambulatory limbs typical of family. Antenna ( Fig. 14A View Figure 14 ) with row of triangular setules on basis, three lateral setae on endopod segment 2, end part of geniculate setae plain, terminal claw comb-like about 1/3 length of endopod segment 2. Tips of molar process on mandible ( Fig. 14B, C View Figure 14 ), maxillule ( Fig. 11D View Figure 11 , exopod not shown), maxilla ( Fig. 14G View Figure 14 ) and maxilliped ( Fig. 14E View Figure 14 ) as described for Porcellidium viride . Triangular first segment of P1 endopod narrow (l/w = 1.3), verY small peg field at lateral corner of fimbriate crescent ( Fig. 14I View Figure 14 ). Serrate spinous seta on segment 3 of P2 endopod almost as long as endopod ( Fig. 15B View Figure 15 ). Serrate spinous seta on P3 endopod segment 2 ( Fig. 15C View Figure 15 ) as long as endopod, large serrate spinous seta on segment 3 longer than endopod (1.45:1). Seta on P4 endopod segment 2 and internal seta on segment 3 spinous, verY finelY serrulate ( Fig. 15E View Figure 15 ). Internal seta on baseoendopod of P5 1/3 length of exopod, exopod lanceolate, dorsal surface with small pits, one subterminal and two apical setae present ( Fig. 15A, D View Figure 15 ). Number of eggs not known, none of the females is ovigerous.

Adult males ( Fig. 13B View Figure 13 ). Cephalosome truncated with rounded shoulders, anterior edge folded ventrally ( Fig. 14F View Figure 14 ). HYaline border and dorsal ornamentation as described for female. Ventral surface of cephalosome not wrinkled, but ventral surface of rostrum with U-shaped ridges or wrinkles ( Figs 14F View Figure 14 , 16A View Figure 16 ). Genital somite with dorsal pits and row of five sensilla on either side ( Fig. 15G View Figure 15 ). Caudal ramus subquadrate (l/w = 0.8), lateral edge convex, medial edge straight, ends in slight bevel with T4 at corner, posterior border straight, T1 and γ setae not recessed, β seta subterminal, fringe of fine border setules between T3 and T4 ( Fig. 16E View Figure 16 ). Antennule ( Fig. 16B View Figure 16 ). No finelY plumulose setae on segment 2, first seta less than 1.5 times length of second seta, segment 3 with knob or peg-like ventral process, no spine close to δ seta, proximal coupling denticle on segment 4 large finely denticulate pad, distal denticle with fine comb-like edge ( Fig. 16B, C, D, F, G View Figure 16 ), segment 5 of dactYlus almost as long as segments 3+4, concave on one side ( Fig. 16D View Figure 16 ), hooked distally ( Fig. 16C View Figure 16 ), segment 6 inconspicuous. P2 endopod terminates in two plumose setae ( Fig. 14H View Figure 14 ). P5 with short row of small setules at base of each terminal seta ( Fig. 15F View Figure 15 ).

Remarks. Bocquet (1948) describes two colour forms of P. lecanoides from Roscoff, BrittanY, France. The first is uniform golden yellow, the second is golden yellow with narrow dark violet median stripe down back and caudal rami. Because of their colouration, shape of the caudal rami and statistical difference in size, the second form was considered a variety of Claus’ P. lecanoides and named P. lecanoides var. roscoffensis . Bocquet did not give a complete description of the new variety, but the specimens collected from Pembrokeshire conform precisely to Bocquet’s illustrations of the caudal rami plus genital double-somite and are considered to be the same species. However, P. lecanoides is a synonym for P.viride and the Pembrokeshire animals do not resemble P. viride . It is considered that Bocquet’s variety should be raised to specific rank as Porcellidium roscoffensis ( Bocquet, 1948) comb. nov.

The antennae of the two male specimens used in this description are either closed or in a position where critical observation of the coupling denticles is difficult. What can be seen is illustrated in Fig. 16 View Figure 16 .

Distribution. Bocquet (1948) records the species as abundant on Bifurcaria tuberculata in tidal pools at Roscoff. It is also abundant in the Bay of Morlaix. Bocquet describes their colour as yellow with a band of violet down the back, but the colour of living animals from Pembrokeshire is not known. They were found among Porcellidium viride washed from a mixture of seaweeds many years after collection and were colourless.