Eucyclops pseudoensifer Dussart, 1984

Suárez-Morales, Eduardo & Walsh, Elizabeth J., 2009, Two new species of Eucyclops Claus (Copepoda: Cyclopoida) from the Chihuahuan Desert with a redescription of E. pseudoensifer Dussart, Zootaxa 2206, pp. 1-22 : 10-15

Eucyclops pseudoensifer Dussart, 1984

( Figs 5–8 )

Material examined. Paratype. Adult female, partially dissected, slide deposited in the Museum National d' Histoire Naturelle ( MNHN Cp 2547), collected from Laguna Mucubají, Venezuela, a high altitude (3 600 m) lagoon in the Andean area near the city of Merida, western Venezuela, October 5, 1980; coll. Evelyn Zoppi. One partially dissected adult male, slide ( NMHN Cp 2548), same date, site, and collector.

Redescription. FEMALE: Total body length of paratype = 0.773 mm from anterior end of cephalothorax to posterior margin of caudal rami. Body relatively robust, widest at midlength of cephalosome in dorsal view; lateral margins of pedigers 3 and 4 straight, produced posteriorly, pediger 4 covering pediger 5. Cephalothorax representing 66 % of total body length. Dorsal surface smooth, antennules short, not reaching anterior margin of first pediger. Urosome, excluding caudal rami, representing 31% of body length.

Antennule ( Fig. 5 A): 12-segmented, armament per segment as follows (s= seta, ae= aesthetasc): 1(8s), 2(4s), 3(2s), 4(5s), 5(2s), 6(2s+ 1 spine), 7(2s), 8(3s), 9(2s), 10(2), 11(2s+1ae), 12(7s). Hyaline, finely serrate membrane on segments 10–12.

Antenna ( Fig. 6 A): 4-segmented, basis with several rows of spinules on caudal surface; largest spinules near insertion of exopodal seta. Basis with exopodal seta. Second segment with one short external seta and subdistal row of spinules. Third segment with 9 setae; inner margin with row of hair-like elements. Fourth segment with 7 setae. Mouthparts as in E. conrowae ( Reid 1992) .

Leg 1 ( Figs 6 B, 7B): Coupler with curved rows of 7–10 spinules on each side. Coxa with strong inner coxal seta; row of spinules on outer proximal surface. Basis with slender outer seta; inner margin with row of long hair-like elements; spinules on insertion of strong, pinnate basipodal seta reaching distal margin of third endopodal segment. Endopod and exopod 3-segmented. Armature as in Table 1 .

Leg 2 ( Fig. 6 C): Coupler pilose, with clusters of long hair-like elements; distal margin with two low, rounded projections. Coxa with strong inner coxal seta; outer margin with rows of spinules. Basis with slender, short basipodal seta not reaching distal margin of first exopodal segment. Distal margin with distomedial expansion between insertion point of exopod and endopod; row of spinules near insertion of endopod. Endopod and exopod 3-segmented. Armature as in Table 1 .

Leg 3 ( Fig. 6 D, 7D): Coupler pilose, with clusters of 8–10 hair-like elements. Coxa with strong inner coxal seta. Basis with slender basipodal seta; row of spinules on insertion point of seta. Endopod and exopod 3- segmented. Armature as in Table 1 .

Leg 4 ( Fig. 7 A, C): Coupler with distal rows of 8–10 long hair-like elements. Coxa with strong, relatively short inner coxal seta, barely reaching distal margin of basipodal segment. Basis with slender basipodal seta on outer margin. Inner and outer spines of terminal endopodal segment serrate along both margins. Endopod and exopod 3-segmented. Armature as in Table 1 . Length ratio of inner/outer terminal spine of Enp 3= 1.1. Length/width ratio of third endopodal segment= 2.2. Insertion point of outer seta of Enp 3= 67%. Length of inner endopodal spine/endopod 3= 1.1.

Leg 5 ( Fig. 5 B): Consisting of article armed with 2 regular setae and 1 spine, middle seta more than twice as long as outer one; spine coarsely serrate, clearly longer than outer seta. Inner spiniform seta 2.4 times as long as bearing segment.

Vestigial leg 6: Small, low plate near lateral margin of genital somite with 2 laterally directed setae and stout, pinnate spine.

Urosome ( Figs 5 C, D): Formed by 5 somites, genital double somite and 3 free somites. Genital double somite representing 11.5 % of total body length (excluding caudal rami); somite smooth on ventral and dorsal surfaces; posterior margins of genital and 2 succeeding somites smooth. Seminal receptacle wide, with short, rounded lateral arms. Anal somite with row of spinules at insertion points of caudal rami; row on ventral margin complete, only 1/3 of dorsal margin with spinules.

Caudal rami ( Figs 5 C-E): Rami representing 11.5 % of total body length and about 0.5 times as long as urosome. Length/width ratio= 4.3. Inner margin smooth. Outer margin armed with row of short spinules arranged in a relatively loose pattern increasing in size distally. Lateralmost terminal spiniform seta relatively long, 0.63–0.68 times as long and 2.6 as wide as caudal ramus. Dorsal seta 0.3 times as long as caudal ramus. Inner medialmost terminal seta longest, about twice as long as outer terminal seta, proximal part smooth, followed by sparse pinnate pattern. Outer terminal setae with same ornamentation pattern. Innermost terminal seta 0.81 times as long as ramus.

MALE: Body elongate, without hairs or pits on dorsal surface. Noticeably smaller, more slender than female. Total body length of allotype = 0.68 mm, cephalothorax representing almost 64% of total body length, urosome length = 0.26 mm. Appendages as in females except for sexual dimorphism. Legs 3 and 4 as in female, except for absence of spinules on outer margin of coxa on leg 3 and shorter hair-like elements on coupler of leg 4 ( Figs 8 A, B).

Antennule ( Fig. 8 D): Geniculate, 14-segmented.

Vestigial leg 6: consisting of broad subquadrate plate with long medial stout spine reaching beyond succeeding posterior urosomite; cluster of spines present on insertion point of spine. Article with 2 outer seta subequal in length and breath. Spine twice as long as 2 lateral setae, reaching about proximal 1/3 of succeeding urosomite.

Urosome: 5-segmented, genital somite largest of urosome. Ventral and dorsal surface of anal somite smooth; distal margin with ventral row of spinules, only ¼ of dorsal margin with spinules. Anal plate smooth. Caudal rami relatively shorter than in female, 3.9 times longer than wide ( Fig. 8 C), margins smooth. Innermost terminal seta relatively longer than in female, 0.94 times as long as ramus.

Figures

FIGURE 5. Eucyclops pseudoensifer Dussart, 1984, adult female paratype (MNHN- 2547) from Laguna Mucubajì, Venezuela. A) antennule; B) leg 5; C) caudal rami, ventral view; D) same, dorsal view; holotype female, E) right caudal rami, ventral view. E from D. Defaye’s drawing of the holotype specimen (in litt.). Scale bars A = 50 μm, B = 25 μm, C – E = 50 μm.

FIGURE 6. Eucyclops pseudoensifer Dussart, 1984, adult female paratype (MNHN- 2547) from Laguna Mucubajì, Venezuela. A) antenna; B) leg 1; C) leg 2; D) leg 3. Scale bars A – D = 50 μm.

FIGURE 7. Eucyclops pseudoensifer Dussart, 1984, A adult female paratype (MNHN- 2547) from Laguna Mucubajì, Venezuela. B-D from D. Defaye’s drawings of the holotype specimen (MNHN-Cp 663) (in litt.). A) leg 4; B) leg 1, coupler and inner margin of coxa and basipod; C) leg 4, ornamentation of coupler; D) leg 3, same. Scale bars A = 50 μm, B – D = 25 μm.

FIGURE 8. Eucyclops pseudoensifer Dussart, 1984, adult male paratype (MNHN- 2548) from Laguna Mucubajì, Venezuela. A) leg 3; B) leg 4; C) caudal rami, dorsal view; D) geniculate antennule. Scale bars A – D = 50 μm.