Tigriopus iranicus, Nazari & Mirshamsi & Arbizu, 2021

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 iranicus sp. nov. Figs 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10

Type material.

Holotype: one adult female (SMF 37258/1-13) dissected, mounted on 13 slides. Allotype: one male (SMF 37259/1-11) dissected, mounted on 11 slides, and 115 paratypes (65 females and 50 males) preserved in alcohol (SMF 37260).

Type locality.

Rock tidal pool on the coast of Iran, Jask, Vanak, 25°32'5"N, 58°52'12"E.

Differential diagnosis.

With marked distinction between prosome and urosome. P1-bearing somite fused to cephalothorax. Female antennule nine-segmented; seven-segmented and chirocerate in male. Mandible with two naked setae on basis, palp with two-segmented endopod and exopod. Maxilla with two endites, each with two setae. P1enp-3 with one claw, one spine, and one naked seta. P1exp-3 with five well-developed claws. Endopodal lobe of female P5 with four pinnate setae. Female P6 with two setae. Inner seta of the male P2enp-2 incorporated to the segment creating curved, pinnate process. Male P5 baseoendopods fused, forming a continuous plate, endopodal lobe without armature, exp with four elements.

Description.

Female. Total body length 630 µm, measured from tip of rostrum to posterior margin of furcal rami. Prosome four-segmented (Figs 1A-C , 2A, B ), consisting of cephalothorax and three free pedigerous somites. First pedigerous somite bearing P1 fused to cephalosome. Cephalothorax and pedigerous somites smooth, furnished with sensilla; hyaline frills smooth without spinules or denticles. Rostrum (Fig. 3A ) well developed, as long as first segment of antennule, bell-shaped, with two pairs of sensilla near apical and lateral margins. Urosome (Figs 1A-C , 2A, B ) five-segmented, comprising fifth pedigerous somite, genital double-somite, two free abdominal somites and telson. Genital double-somite completely fused dorsally and ventrally, subdivided laterally by internal chitinous rib. Urosome ornamented with row of spinules laterally. Genital double-somite and first free abdominal somite clothed with sensilla dorsally. First and second free abdominal somites with posterior row of spinules ventrally. Telson with spinular rows ventrally and laterally, with two sensilla on dorsal distal margin. Anal operculum semicircular, smooth (Fig. 2A ).

Furcal rami (Figs 2A, B , 7A ). Divergent, slightly longer than wide, furnished with oblique spinular row on dorsal surface and row of spinules ventrolaterally as illustrated. Seta I located on outer margin, approximately at mid-length of ramus; seta II positioned dorsally; seta III longer than seta II, placed on outer distal corner; seta IV pinnate; seta V longest and pinnate; seta VI as long as seta III, positioned on inner corner; seta VII tri-articulated, located dorsally.

Antennule (Fig. 3B ). Nine-segmented; first three segments longer than six apical segments combined; first segment with row of spinules; fourth segment with one seta fused basally to aesthetasc and two naked setae; apical acrothek on last segment with two setae fused at their bases and one aesthetasc. Armature formula: 1(1), 2(9), 3(7), 4(3+(1+ae)), 5(1), 6(4), 7(1), 8(3), 9(5+acrothek).

Antenna (Fig. 3C ). Three-segmented, composed of coxa, allobasis, and one free endopodal segment. Coxa without ornamentation. Allobasis ornamented with row of spinules and long setules proximally, abexopodal seta bipinnate. Free endopodal segment ornamented with row of spinules close to insertion site of proximal lateral spine, and with frill and minute spinules on outer distal corner; with two pinnate spines on lateral margin, one pinnate spine, four geniculate and two tiny naked setae distally. Exopod three-segmented; first segment longest with two pinnate setae; second segment with one pinnate seta; last segment with one pinnate seta incorporated into segment, and one tiny bare seta with spinules at its base.

Labrum (Fig. 4A ). Broad and well developed, triangular in lateral view, ornamented with setules along outer margin.

Mandible (Fig. 4B ). Coxa with well-developed gnathobase. The latter with six blunt and two multicuspidate teeth and one pinnate seta. Basis rectangular with two smooth setae. Both exopod and endopod two-segmented. Enp-1 with three naked setae laterally, two of them fused basally; enp-2 with five naked setae on distal margin. Exp-1 with two smooth setae on inner margin and spinules on outer margin; exp-2 with three naked setae.

Maxillule (Fig. 4C, D ). Arthrite of praecoxa with one ventral pinnate spine, tiny apical spine, two pinnate and four naked apical spines, and two smooth surface setae, ornamented with spinules on posterior surface, and with few lateral spinules medially. Coxal endite (Fig. 4D ) cylindrical, with three naked setae, with spinules subdistally. Basis with two lateral smooth setae, and one pinnate and three smooth distal setae. Endopod one-segmented, cylindrical, with three naked setae. Exopod one-segmented, with four naked setae.

Maxilla (Fig. 4E ). Syncoxa bearing one praecoxal and one coxal endite, each armed with two setae, with two lobes (probably the remnant of endites) between syncoxal endites, with spinules on praecoxal endite, with some medial and some distal spinules on syncoxa. Allobasis prolonged into a strong pinnate claw, with one anterior naked seta and one posterior slender smooth, and one strong bipinnate seta. Endopod one-segmented, carrying two naked setae.

Maxilliped (Fig. 3D ). Syncoxa with spinule patch on outer margin and with distal spinule row; with one naked inner distal seta. Basis with strong spinules on inner margin and one naked seta. Endopod drawn out into a developed pinnate claw carrying a process with two smooth setae.

Swimming legs P1-P4 (Figs 5A, B , 6A, B ) biramous, each ramus three-segmented and well-ornamented with spinules, exopod longer than endopod. Setal formula as follows:

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	I-I	I-0; I-1; V	0-1, 0-0; II+1
Leg 2	0-0	I-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. 5A ). Intercoxal sclerite rectangular, longer than wide and smooth. Praecoxa and coxa ornamented with spinular rows on distolateral anterior surface. Basis bearing one inner and one outer spinulose flagellate spine, with rows of spinules on anterior surface as shown. Endopod approximately as long as first exopodal segment; enp-1 longest, with one long inner seta inserted at two-thirds length of segment, ornamented with setules and spinules as depicted, with spinule row on inner and outer margins; enp-2 wider than long, unarmed, with few large outer spinules; enp-3 with one strong curved pinnate claw, one spine and one tiny smooth seta at base of the claw, with outer spinular row. Exp-1 longest, bearing one pinnate flagellate outer spine distally, with row of outer spinules; Exp-2 ornamented with setules and spinules as shown, with one outer pinnate flagellate spine at two-thirds length of segment, and one inner subapical pinnate seta; exp-3 shortest, armed with five claw-like spines.

P2 (Fig. 5B ). Intercoxal sclerite smooth, longer than wide and curved. Coxa triangular, with proximal and outer subdistal spinular rows, with distal frill on anterior surface, and with pore near inner margin. Basis with spinules at base of outer spine and at base of exopod, with inner distal frill and pore close to insertion site of exopod, with outer flagellate pinnate spine. Endopodal segments with strong outer spinules; enp-1 and -2 with one inner seta ornamented with setules proximally and with small spinules distally; enp-3 with one spinulose and two pinnate setae, and one blunt pinnate spine. Exopodal segments with strong outer spinules; exp-1 and exp-2 with anterior distal frill, with one outer naked spine and one inner pinnate seta; exp-3 with three naked outer spines, one outer distal element ornamented as shown and one inner distal pinnate seta, and two pinnate inner setae.

P3 (Fig. 6A ). Coxa with spinules on outer distal corner and frill on inner distal border. Basis with strong outer spinules, with smooth outer seta. Segments of both rami with spinules on outer margins. Enp-1 and enp-2 armed with one long inner seta ornamented as depicted; enp-1 with, enp-2 without inner distal frill; enp-3 with three pinnate setae and one unipinnate spine. Exp-1 and exp-2 with anterior frill distally, with one outer pinnate spine and one inner seta ornamented as figured; exp-3 with three outer pinnate spines, one outer and one inner distal element as shown, and two inner setae.

P4 (Fig. 6B ). Coxa with anterior frill distally and with outer spinules. Both exopodal and endopodal segments ornamented with outer spinules. Enp-1 with frill on anterior distal margin, bearing one inner pinnate seta; enp-2 unarmed; enp-3 with one pinnate spine and three pinnate setae. Exp-1 with distal frill and outer pore on anterior surface, with one pinnate outer spine and one pinnate inner seta; exp-2 with anterior distal frill, with pinnate outer spine and pinnate inner seta; exp-3 with three outer pinnate spines, one outer and one inner distal element, and three inner setae of which medial spinulose.

P5 (Fig. 7B ). Exopod and baseoendopod separate; ornamented with spinules as illustrated; baseoendopod bearing smooth outer basal seta; endopodal lobe with four pinnate setae, with one tube-pore near innermost seta and two pores on anterior surface; exopod rectangular, with five pinnate setae and one pore on anterior surface.

P6 (Fig. 7A ). One-segmented, bearing one naked and one pinnate seta.

Genital field (Fig. 7A ). Situated in the middle of the genital double-somite, with one median genital pore at the boundary between genital somite and first abdominal somite.

Male (Fig. 8A-C ). Habitus as in female except for genital somite separated from first abdominal somite. Total body length 685 µm measured from tip of rostrum to posterior margin of furcal rami. Sexual dimorphism expressed in antennule, antenna (the latter as in female, but without abexopodal seta), P2, P5 and P6.

Antennule (Fig. 9A, B ). Seven-segmented, chirocerate, with geniculation between sixth and seventh segments. First segment with anterior spinules; segment six largest and swollen, with four multicuspidate elements ventrally; segment seven with acrothek and several denticles on anterior surface. Armature formula: 1(1), 2(1), 3(11), 4(1), 5(1), 6(11+(1+ae)), 7(7+acrothek).

P2 (Fig. 10A ). Praecoxa small and triangular. Coxa and basis as in female, except for basis without anterior pore. Exopod as in female except for additional anterior pore on exp-1. Endopod three-segmented; enp-1 largely as in female; enp-2 with outer apophysis, inner element comparatively shorter than in female and robust, incorporated into the segment, with row of inner strong spinules; enp-3 small, with three pinnate and one small naked seta.

P5 (Fig. 10B ). Baseoendopods of both legs fused forming continuous plate; endopodal lobe completely incorporated into segment, unarmed, with medial transverse spinular row as shown; outer basal seta naked, with spinules at its base. Exopod rectangular, ornamented with anterior and posterior spinules, with four elements, innermost longest.

P6 (Fig. 10C ). Symmetrical, represented by two pinnate and one naked seta, ornamented with spinules.

Etymology.

The specific epithet iranicus refers to the country where the new species was found. It is in the nominative singular. Gender masculine.

Figures

Figure 1. Tigriopus iranicus sp. nov. female. Confocal laser microphotograph A habitus, dorsal B habitus, lateral C habitus, ventral. Scale bar: 100 µm.

Figure 2. Tigriopus iranicus sp. nov. female A habitus, dorsal B habitus, lateral. Scale bar: 50 µm.

Figure 3. Tigriopus iranicus sp. nov. female A rostrum, dorsal B antennule C antenna D maxilliped. Scale bars: 20 µm.

Figure 4. Tigriopus iranicus sp. nov. female A labrum B mandible C maxillule D coxal endite of the maxillule E maxilla. Scale bars: 20 µm.

Figure 5. Tigriopus iranicus sp. nov. female A P 1 B P 2. Scale bar: 20 µm.

Figure 6. Tigriopus iranicus sp. nov. female A P 3 B P 4. Scale bar: 20 µm.

Figure 7. Tigriopus iranicus sp. nov. female A urosome, ventral B P 5. Male C urosome, ventral D furcal ramus, dorsal. Scale bars: 20 µm.

Figure 8. Tigriopus iranicus sp. nov. male. Confocal laser microphotograph A habitus, dorsal B habitus, lateral C habitus, ventral. Scale bar: 100 µm.

Figure 9. Tigriopus iranicus sp. nov. male A antennule, ventral B antennule, lateral view. Scale bar: 20 µm.

Figure 10. Tigriopus iranicus sp. nov. male A P 2 B P 5 C P 6. Scale bars: 20 µm.