Pseudocletodes vararensis Scott & Scott, 1893

Kihara, Terue Cristina & Huys, Rony, 2009, Contributions to the taxonomy of the Normanellidae (Copepoda, Harpacticoida): description of a new genus from the Brazilian continental shelf and re-assignment of Pseudocletodes vararensis Scott & Scott, 1893 (ex Nannopodidae), Zootaxa 2233, pp. 1-38 : 20-31

Pseudocletodes vararensis Scott & Scott, 1893

( Figs 12–20 )

Type locality. Scotland, Moray Firth; among Filograna implexa Berkeley, 1835 (Polychaeta, Serpulidae ). Material examined. Syntype female in ethanol, subsequently dissected on 9 slides (reg. nos NHM 1911.11.8.45174–175); syntype male in ethanol, subsequently dissected on 9 slides. (reg. nos NHM 1911.11.8.45174–176).

Redescription. FEMALE ( Figs 12–18 ). Total body length 871 µm (N = 1). Body slender. Largest width measured at posterior margin of cephalic shield: 171 µm. Urosome slightly narrower than prosome ( Fig. 12 A– B).

Cephalic shield with smooth posterior margin, pleural area well developed and rounded, posterolateral angles minutely crenate, ornamentation consisting of sensilla as illustrated in figures 12A–B; without minute spinules as found on free body somites.

Pedigerous somites ( Fig. 12 A–B) covered with minute spinules and with sensillar pattern as illustrated. All prosomites without defined hyaline frill; pleurotergites well developed and rounded; posterior margin serrate.

All urosomites ( Figs 12 A–B; 13A) with surface ornamentation consisting of minute spinules dorsally and ventrally; posterior margin distinctly serrate dorsally and laterally; ventral posterior margin as shown in figure 13A.

Genital double-somite ( Figs 12 A–B; 13A) with original segmentation indicated by a transverse, serrate surface ridge dorsally and dorsolaterally, and a short surface suture ventrolaterally; completely fused ventrally. Genital field ( Fig. 13 B) with large copulatory pore located in a median depression. Gonopores fused medially forming a single genital slit covered on both sides by opercula derived from the sixth legs. P6 with a small protuberance bearing one pinnate outer seta and one naked inner seta.

Anal somite ( Fig. 13 A–C) with well developed, denticulate anal operculum flanked by a row of spinous processes. Anal opening with a fringe of small denticles, and bordered by spinules ventrally. Surface ornamentation consisting of a pair of sensilla dorsally and a pair of pores ventrally; posterior margin with row of spinules.

Caudal rami ( Figs 13 C; 14A–B) lamelliform and elongate, about twice as long as wide; with virtually straight outer margin and convex inner margin. Each ramus with a dorsal pore (between setae II and VII), 2 ventral tube-pores near distal margin and seven setae: seta I naked, shortest and closely set to naked seta II; seta III naked and positioned ventrolaterally; setae IV and V not fused basally, pinnate and with fracture plane (seta V longest, about 1.5 times as long as ramus); seta VI bare; seta VII bi-articulate at its base and sparsely plumose. Surface ornamentation consisting of minute spinules and rows of small denticles as shown in figures 13C, 14A–B; a few spinules present around bases of setae I–III and near inner distal corner. Posterior margin partially serrate and with a ventral extension covering the bases of setae IV–VI.

Rostrum ( Fig. 14 C) triangular, apex pointed; completely defined at base; with 1 pair of tiny sensilla and 1 middorsal tube-pore near the apex; dorsal surface smooth.

Antennule ( Fig. 14 D) 6-segmented, segment 3 longest. Segment 1 with spinular row around anterior margin and at base of seta. Segment 3 with aesthetasc fused basally to a seta and arising from a distinct pedestal. Armature formula: 1-[1 pinnate], 2-[4 + 5 pinnate + 1 pinnate spine (+ 1 element missing, indicated by dorsal scar in Fig. 14 D)], 3-[3 + 1 pinnate + 2 pinnate spines + (1 + ae)], 4-[1], 5-[2 + 1 pinnate spine], 6- [4 + 1 pinnate spine (+ 2 elements missing, indicated by dorsal scars in Fig. 14 D) + acrothek]. Structure of acrothek unknown (position indicated by arrow in Fig. 14 D). Pinnate spines on segments 5 and 6 very large and with coarse spinules.

Antenna ( Fig. 15 A) 3-segmented comprising coxa, allobasis and free distal endopod segment. Basis and proximal endopod segment completely fused, forming an elongate allobasis bearing 2 abexopodal pinnate setae. Exopod almost 2.5 times longer than wide, with 1 pinnate seta laterally, and 2 pinnate setae apically. Endopod 1.5 times longer than allobasis, outer margin with a row of long spinules and distal margin with a row of fine spinules; lateral armature consisting of 2 pinnate spines, distal armature consisting of 2 pinnate spines and 3 geniculate setae, outermost one being pinnate and fused basally to a short seta.

Labrum ( Fig. 15 B) well developed, with spinular ornamentation along distal margin.

Paragnaths ( Fig. 15 B) well developed lobes, with spinular ornamentation along distal and inner margins.

Mandible ( Fig. 15 C) with well developed gnathobase bearing several multicuspidate teeth around distal margin and 1 basally fused pinnate seta at dorsal corner. Palp small, biramous but only the exopod is defined at its base. Basis with 1 pinnate seta. Exopod 1-segmented, small, with 1 pinnate seta apically and few spinules along outer margin. Endopod fused to basis, with 1 lateral and 3 distal pinnate setae.

Maxillule ( Fig. 15 D) with large praecoxa bearing a few long spinules around distal outer margin; arthrite strongly developed, with 2 naked setae on anterior surface and 8 spines/setae around distal margin. Coxa with cylindrical endite bearing 1 pinnate seta. Basis with 2 endites, represented by 2 plumose and 1 naked + 2 pinnate setae, respectively; with rows of spinules on anterior surface. Endopod incorporated with basis, represented by 2 plumose setae. Exopod 1-segmented, with 2 sparsely plumose setae.

Maxilla ( Fig. 16 A). Syncoxa with very long outer spinules and three endites; praecoxal endite small and cylindrical, with one pinnate seta; proximal coxal endite with one pinnate spine fused to endite, and 2 naked setae; distal coxal endite with 1 spine and 2 naked setae. Allobasis drawn out into a strong, slightly curved claw. Accessory armature consisting of 1 naked seta. Endopod represented by 3 naked setae.

Maxilliped ( Fig. 16 B) with 2 spinule rows on syncoxa. Basis with a few spinules near outer distal corner. Endopod drawn out into a long pinnate claw; accessory armature consisting of a long naked seta.

Swimming legs P1–P4 ( Figs 16 C; 17A–B; 18A) with well developed praecoxae ornamented with spinules along outer distal corner.

P1 ( Fig. 16 C) with large coxa bearing strong spinules along outer margin, and minute denticles and fine setules on anterior surface. Basis with a well developed, flattened, pinnate spine at inner distal corner and stout pinnate outer spine; with very long setules along inner margin and large spinules along distal margin and around base of spines. Exopod 3-segmented; all segments with strong spinules along outer margin and around outer distal corner; exp-1 with 1 stout pinnate outer spine; exp-2 with 1 pinnate, outer spine and 1 sparsely plumose inner seta; exp-3 with 3 pinnate spines along outer margin, 2 pinnate setae apically and 1 sparsely plumose inner seta (note that the presence of the latter element is an aberration; for normal condition see male: Fig. 20 B). Endopod absent.

P2–P4 ( Figs 17 A–B; 18A) coxa with strong spinules along outer margin, and minute denticles and/or fine setules on anterior surface. Basis with long setules along inner margin (P2 only) and with spinules near insertion of endopod and at base of outer pinnate spine (P2) or plumose setae (P3–P4). Exopods 3-segmented; all segments with strong spinules along outer margin and near outer distal corner; with long setules along inner margin of exp-1 and -2. Endopods 2-segmented, with scattered spinules along outer margin as figured. P2 enp-2 twice as long as enp-1; endopod reaching to just beyond distal margin of exp-2. P3 enp-2 almost 3 times as long as enp-1; endopod reaching to proximal third of exp-3. P4 enp-2 6 times as long as enp-1, endopod reaching to just beyond distal margin of exp-2. Spine and setal formula as for the genus.

P5 ( Fig. 18 B) baseoendopod with short, outer setophore bearing plumose basal seta; with one pore near articulation with exopod. Endopodal lobe elongate, extending to distal margin of exopod, with 3 pinnate setae along inner margin and 2 pinnate setae apically; outer and inner margins with long setules; with tube-pore between distal inner and inner apical setae. Exopod elongate-oval, tapering distally, inner margin with very long setules, outer margin with short setules; with 4 pinnate setae along outer margin, 1 pinnate seta apically and 1 subapical inner element (missing on both sides; insertion site marked by arrow in Fig. 18 B).

MALE ( Figs 19–20 ). Body more slender than in female. Body length 728 µm (N = 1). Largest width measured at medial portion of cephalic shield: 125 µm. Urosome slightly narrower than prosome ( Fig. 19 A). Cephalic shield ( Fig. 19 A) with posterior margin weakly serrate; with pattern of sensilla and pores as figured. Pedigerous somites covered with minute spinules. Prosomites with serrate posterior margin. Urosome ( Fig. 19 A–B) with surface ornamentation consisting of patches of minute spinules, sensilla and pores as figured; posterior margins irregularly serrate and with spinules. Caudal rami ( Fig. 20 A) more slender than in female.

Antennules missing in the only male available.

P1 exopod 3-segmented. Exp-3 with 3 pinnate outer spines and 2 pinnate setae apically ( Fig. 20 B).

P3 endopod ( Fig. 20 C) 2-segmented, modified. Enp-2 more slender than in female; outer margin produced into a subdistal pinnate apophysis (homologous with outer spine of enp- 2 in female); proximal inner seta distinctly shorter than in female; distal inner and both apical setae slightly shorter than in female.

Fifth pair of legs ( Fig. 20 D) not fused medially; defined at base. Baseoendopod with a short setophore bearing an outer basal seta (missing on both sides; original insertion site marked by arrow in Fig. 20 D). Endopodal lobe well developed, triangular; with 2 pinnate setae apically and 1 pinnate inner seta. Exopod about 1.2 times as long as maximum width, with 2 pinnate apical setae and 2 pinnate outer setae.

Sixth pair of legs ( Fig. 20 E) asymmetrical, represented on both sides by a small plate (fused to ventral wall of supporting somite along one side, articulating at base and covering gonopore along other side); outer distal corner produced into a cylindrical process bearing 1 pinnate middle seta flanked by 2 naked setae.

Variability. Except for the aberrant armature pattern on P1 exp-3 of the female syntype no additional variability was observed. Both syntypes showed only 3 setae on the antennary exopod (both left and right antennae) whereas Scott and Scott (1893: Plate XII-Fig. 6) figured an additional lateral seta. Given that 4 setae is the norm in the superfamily Laophontoidea in general, and the family Normanellidae in particular it is not unlikely that the 4-setae condition is the typical one in P. vararensis .

Figures

FIGURE 12. Pseudocletodes vararensis Scott & Scott, 1893 (Ƥ): (A) habitus, dorsal; (B) habitus, lateral. Scale bar: 50 μm.

FIGURE 13. Pseudocletodes vararensis Scott & Scott, 1893 (Ƥ): (A) urosome, ventral [P 5 - bearing somite omitted]; (B) genital field; (C) anal somite and caudal rami, dorsal. Scale bars: 10 μm (B, C), 50 μm (A).

FIGURE 14. Pseudocletodes vararensis Scott & Scott, 1893 (Ƥ): (A) right caudal ramus, lateral; (B) right caudal ramus, ventral; (C) rostrum, dorsal; (D) antennule, ventral [arrows indicate missing apical elements]. Scale bars: 10 μm.

FIGURE 15. Pseudocletodes vararensis Scott & Scott, 1893 (Ƥ): (A) antenna; (B) labrum with paragnath, anterior; (C) mandible; (D) maxillule, anterior. Scale bars: 10 μm.

FIGURE 16. Pseudocletodes vararensis Scott & Scott, 1893 (Ƥ): (A) maxilla; (B) maxilliped; (C) P 1, anterior [arrow indicating aberrant supernumerary seta]. Scale bars: 10 μm.

FIGURE 17. Pseudocletodes vararensis Scott & Scott, 1893 (Ƥ): (A) P 2, anterior; (B) P 3, anterior. Scale bar: 10 μm.

FIGURE 18. Pseudocletodes vararensis Scott & Scott, 1893 (Ƥ): (A) P 4, anterior; (B) P 5, anterior [arrow indicating insertion scar of dislodged seta]. Scale bars: 10 μm.

FIGURE 19. Pseudocletodes vararensis Scott & Scott, 1893 (3): (A) habitus, dorsal; (B) urosome [P 5 - bearing somite omitted], ventral. Scale bars: (A, B) 50 μm.

FIGURE 20. Pseudocletodes vararensis Scott & Scott, 1893 (3): (A) anal somite and caudal rami, dorsal; (B) P 1 exp- 3, anterior; (C) P 3 enp- 2, anterior; (D) P 5, anterior [arrow indicating insertion scar of dislodged outer basal seta]; E. sixth legs, anterior. Scale bars: 10 μm.