Tigriopus raki Bradford, 1967

Nazari, Fatemeh, Mirshamsi, Omid & Arbizu, Pedro Martinez, 2021, Tigriopus iranicus sp. nov., a new species of Harpacticidae (Copepoda, Crustacea) from Iran, with a redescription of T. raki Bradford, 1967, ZooKeys 1035, pp. 115-144 : 115

Tigriopus raki Bradford, 1967

Material examined.

One female ( SMF 37261 /1-13) and one male ( SMF 37262 /1-10) paratype (NIWA 1610 P-33) dissected and mounted on slides, and three females and two males preserved in ethanol ( SMF 37263 ) .

Type locality.

Leigh, north of Auckland, at about 36°30'S, 174°45'E on the east coast. Habitat: marine, in splash zone pool.

Redescription.

Female. Total body length 560 µm, measured from tip of rostrum to posterior margin of furcal rami. Few sensilla scattered on body surface (Fig. 12A, B ).

Prosome (Figs 11A, B , 12A, B ). Four-segmented, including cephalothorax with first pedigerous somite incorporated, and three free pedigerous somites. Tergite of first pedigerous somite remarkable from dorsal and lateral view (Figs 11A, B , 12A, B ; marked by an arrow in Fig. 12A, B ). Hyaline frills on posterior and lateral margins smooth. Rostrum (Fig. 13A ) bell-shaped, defined at base, without sensilla.

Urosome (Figs 11A, C , 12A, B ). Five-segmented, comprising fifth pedigerous somite, genital double-somite, two free abdominal somites and telson. Genital double-somite completely fused dorsally and ventrally, boundary between two somites slightly distinguishable by lateral internal chitinous rib. With spinulose rows on first and second abdominal somites. Anal operculum semicircular, smooth.

Furcal rami (Fig. 12C ) slightly wider than long; with outer and distal spinulose rows. Lateral seta I smooth, implanted in middle of ramus. Seta II smooth, longer than seta I, located subdistally. Seta III smooth, displaced ventrally, subdistal. Setae IV and V pinnate, located on distal margin. Seta VI smooth inserted on distal, inner corner. Seta VII tri-articulated and smooth, dorsally located near distal inner margin.

Antennule (Fig. 13A ). Nine-segmented. All segments smooth except for first segment with few spinules. Five apical segments shorter than first two segments combined. Segment eight very small. Ninth segment with apical acrothek. Armature formula: 1 (1), 2(12), 3(8), 4(4+(1+ae)), 5(1), 6(4), 7(3), 8(1), 9(5+acrothek).

Antenna (Fig. 13B ). Consisting of coxa, allobasis and one free endopodal segment. Coxa without ornamentation. Allobasis longest, with proximal inner spinules, with pinnate abexopodal seta. Exopod three-segmented; first segment longest with two pinnate setae; second segment shortest, with one pinnate seta; last segment bearing two pinnate setae. Free endopodal segment ornamented with long spinules and with outer distal frill, with two lateral and one subdistal inner spine, four apical pinnate setae, and one tiny smooth outer distal seta.

Mandible (Fig. 13C, D ). Coxa with anterior row of spinules. Gnathobase well developed; with two rows of blunt teeth and a comb-like structure; with one long pinnate seta. Basis ornamented with spinules; with one naked seta. Both rami one-segmented. Endopod with two pinnate and one naked seta laterally; with five distal setae fused at their bases. Exopod with two lateral setae, and four apical naked elements fused basally to segment.

Maxillule (Fig. 14A ). Arthrite of praecoxa well developed; ornamented with spinules; bearing one tiny and eight developed spines apically, with two surface setae. Coxal endite with spinular row on distal margin; with three spinulose setae. Basis ornamented with spinules on anterior and posterior surface; with three subdistal naked setae, and two distal elements of which one visibly stronger and spinulose. Endopod with three naked setae fused to segment. Exopod rectangular, armed with three naked setae.

Maxilla (Fig. 14B, C ). Syncoxa with three endites; ornamented with subdistal medial and outer spinules; praecoxal endite bilobed, each lobe with two pinnate setae; coxal endites (Fig. 14C ) with two and three pinnate setae, respectively. Allobasis with strong unipinnate claw and one posterior and one anterior strong pinnate seta. Endopod one-segmented, with two naked setae.

Maxilliped (Fig. 14D ). Syncoxa ornamented with hair-like outer spinules and with inner spinules; with one naked inner seta. Basis with medial spinules of variable lengths; with one spinulose seta. Endopod drawn out into strong claw; with one cylindrical process carrying one naked seta apically and one tiny naked seta basally.

Swimming legs 1-4 (Figs 14E , 15A , 16A, B ) biramous; rami three-segmented; ornamented with spinules of different sizes; exopod slightly longer than endopod. Setal formula as follows:

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-1	I-0; I-1; V	0-1, 0-0; II+1
Leg 2	0-0	1-0	I-1; I-1; III, II, 2	0-1; 0-1; I,2,1
Leg 3	0-0	1-0	I-1; I-1; III, II, 2	0-1; 0-1; I,2,1
Leg 4	0-0	1-0	I-1; I-1; III, II, 3	0-1; 0-0; I,2,1

P1 (Fig. 14E ). Intercoxal sclerite slender and smooth. Praecoxa triangular, with anterior medial spinules. Coxa ornamented with large outer and distal medial spinules. Basis with spinules on anterior surface; outer seta stout and pinnate; inner seta long and naked. Endopod shorter than first two exopodal segments combined; enp-1 approximately as long as exp-1, with one inner long pinnate seta at two-thirds length of segment, with long inner spinules; enp-2 and enp-3 small, enp-2 unarmed, enp-3 armed with two strong claws and one tiny seta at base of claw. Exp-1 with spinules along outer margin, outer flagellate spine unipinnate; exp-2 with curved outer margin, with one pinnate outer spine at about mid-length, and one pinnate inner distal seta; exp-3 reduced, with four claws and one spine.

P2 (Fig. 15A ). Praecoxa small and triangular, with spinules as shown. Coxa ornamented with spinules. Basis with pinnate outer seta and anterior spinules. Endopodal segments with spinules on outer margin; enp-1 and enp-2 with long pinnate inner seta; enp-3 with three pinnate setae and one pinnate spine. Exp-1 and -2 armed with one outer pinnate spine and one pinnate inner seta; exp-3 with three outer pinnate spines, one outer and one inner element ornamented as shown, and two inner pinnate setae.

P3 (Fig. 16A ). Intercoxal sclerite rectangular, smooth and longer than wide. Similar to P2, except praecoxa unornamented and basal outer seta naked.

P4 (16B). Praecoxa triangular and unornamented. Coxa and basis largely as in P3. Enp-1 with one large pinnate inner seta; enp-2 unarmed; enp-3 with three pinnate setae and one pinnate spine. Exp-1 and -2 each with one outer pinnate spine and one inner pinnate seta; exp-3 with three pinnate outer spines, one outer and inner distal element ornamented as shown, and three pinnate setae.

P5 (Fig. 17B ). Baseoendopod and exopod separated. Basal outer seta long and naked. Endopodal lobe ornamented with long spinules along inner and outer margin, with inner tube-pore and median pore on anterior surface, with four pinnate setae. Exopod rectangular, longer than endopodal lobe, furnished with spinules on anterior and posterior surface, with five pinnate setae.

P6 (Fig. 17A ). Situated on anterior part of genital-double somite, with two pinnate and one small naked seta.

Genital field (Fig. 17A ). Copulatory pore approximately in middle of genital double-somite.

Male (Fig. 18A-C ). Habitus as in female, except genital somite separated from first abdominal somite. Total body length 600 µm measured from tip of rostrum to posterior margin of furcal rami. Sexual dimorphism expressed in antennule, antenna (without abexopodal seta), P2, P5 and P6.

Antennule (Fig. 19A, B ). Seven-segmented, chirocerate; with geniculation between segments 6 and 7. First segment ornamented with spinules around seta. Segment 5 smallest. Segment 6 largest and swollen, with three multicuspidate elements and one club-like element ventrally. Segment 7 with membranous element and three ventral teeth. Armature formula as follows: 1 (1), 2(1), 3(12), 4(7), 5(1), 6(13+(1+ae)),7(7+acrothek).

P2 (Fig. 15B ). Coxa with spinules and frill anteriorly. Basis with anterior frill, and with outer naked seta. Enp-2 with outer apophysis and pinnate inner seta. Enp-3 with one pinnate inner seta, two naked reduced apical setae, and one naked spine.

P5 (Fig. 17C ). Baseoendopod of both legs fused, endopodal lobe completely absorbed into segment, unarmed. Basal seta naked and long. Exopod rectangular with four strong pinnate setae.

P6 (Fig. 17D ). Symmetrical, with one outer naked and one inner pinnate seta.

Figures

Figure 11. Tigriopus raki. female. Confocal laser microphotograph A habitus, dorsal B habitus, lateral C habitus, ventral. Scale bar: 100 µm.

Figure 12. Tigriopus raki female A habitus, dorsal (tergite of first pedigerous somite arrowed) B habitus, lateral (tergite of first pedigerous somite arrowed) C anal somite and furcal rami, dorsal. Scale bars: 50 µm (A, B), 20 µm (C).

Figure 13. Tigriopus raki female A rostrum and antennule B antenna C mandible D cutting edge of mandible. Scale bars: 20 µm (A-C), 10 µm (D).

Figure 14. Tigriopus raki female A maxillule B maxilla C medial and distal syncoxal endites of the maxilla D maxilliped E P 1. Scale bars: 20 µm.

Figure 15. Tigriopus raki female A P 2 B male. P 2. Scale bar: 20 µm.

Figure 16. Tigriopus raki female A P 3 B P 4. Scale bar: 20 µm.

Figure 17. Tigriopus raki female A urosome, ventral B P 5. Male C P 5 D P 6. Scale bars: 20 µm.

Figure 18. Tigriopus raki male. Confocal laser microphotograph A habitus, dorsal B habitus, lateral C habitus, ventral. Scale bar: 100 µm.

Figure 19. Tigriopus raki male A antennule, ventral B last segment of the antennule. Scale bar: 20 µm.