taxonID	type	description	language	source
242F878AFFC6933DFF38A864001709E2.taxon	diagnosis	Diagnosis. Medium-sized species (833 – 1410 μm) with slender, cyclopiform habitus. Genital double-somite about as long as broad, widest at first third. Receptaculum seminis with bulky anterior part and almost unexpanded posterior part in salisae - group or with thin anterior part and sac-like posterior part in uruguayensis - group. Anal somite with denticles along most of the lower margin; anal operculum weakly developed, almost straight in salisae - group or rather strongly developed in uruguayensis - group. Caudal branches cylindrical, parallel, from 3.3 to 5.1 times as long as wide; inner surface bears rows of hairs-setules and denticles (one proximal row of hairs in salisae - group and several rows of hairs in uruguayensis - group); outer surface may bear transverse row of denticles in proximal third of branch (uruguayensis - group); lateral seta longer than width of caudal branch, attached at level of lower quarter / third of length of outer margin, plumed with long hairs, with or without denticles at point of attachment; innermost seta is longer than outer one (1.2 – 1.6: 1) and shorter or subequal to length of caudal rami (0.6 – 1.1: 1), uniformly plumed with long hairs; outermost seta from 0.5 to 0.8 times as long as caudal ramus, uniformly plumed with long hairs, has denticles at point of attachment; dorsal seta shorter than outermost seta, subequal or longer (0.75 – 1.2: 1) and from 0.4 to 0.8 times as long as caudal ramus, usually with few long hairs distally. Antennule 17 - segmented, short, does not extend beyond middle of first free thoracic somite. Antenna with long exopodite seta; endopodite segment 2 with 9 setae. Labrum with rounded lateral projections and 10 - 12 blunt teeth on cutting edge; frontal surface with 2 rows of long hairs. Mandible with several teeth and plumose seta on cutting edge; palp with two long plumose and one short naked seta. Maxillule of typical cyclopid structure; palp surface without ornamentation. Maxilla 5 - segmented, with first two segments partly fused, without ornamentation on surface. Maxilliped 4 - segmented; segment setation: 3 / 2 / 1 / 3 or 3 / 1 / 1 / 3; second segment ornamented with two or three lateral rows of spinules and one medial group of spinules; third segment bearing one medial group of spinules. Swimming legs two-branched, three-segmented. Exp 1 and Exp 2 with 1 inner seta and 1 outer spine. Exp 3 spine formula 2 / 3 / 3 / 3 or 3 / 4 / 4 / 4; setal formula 4.4.4.4. Enp 1 with 1 inner seta; Enp 2 with 2 inner setae. Enp 3 spine formula 1 / 1 / 1 / 2; setal formula 5.5.5.3. All swimming legs with finely plumose setae, except lateral-most seta of P 1 Exp 3, which has tiny spinules along its lateral side. Intercoxal plate has simplified ornamentation; in a number of species it is bare on both sides; in some there are hairs on frontal side of some swimming legs; in some species, there are denticles on caudal side of P 4 intercoxal plate. Inner spine of P 4 Enp 3 may be longer or shorter than outer spine, or they may be subequal. Distal setae of P 4 Enp 3 may extend beyond tips of distal spines in some species. P 1 Bas with inner spine, which may be homogeneously covered with setules of similar length or heterogeneously covered with long setules proximally and short setules distally. P 1 Bas with or without distal arc of spinules between Enp and Exp frontally. Fifth pair of legs two-segmented; first (proximal) segment about as wide as long or slightly wider, with 1 outer seta; second (distal) segment cylindrical, longer than wide, armed with 1 apical seta and 1 inner spine. Inner spine is almost as long as distal segment or longer (0.9 – 2.0: 1), with several denticles at insertion site. Sixth leg represented by small plate armed with two short smooth spines and plumose longer outer seta. Males are noticeably shorter and more slender than females. Structure of appendages similar to females, although length ratios slightly differ. Antennule geniculate. P 6 armed with strong inner spine and two plumose setae. New genus currently includes five species.	en	Alekseev, Victor, Chaban, Olga (2024): Archaeodiacyclops, new genus with “ archaic ” features (Crustacea, Copepoda, Cyclopoida), with description of new species from water bodies of northern Sakhalin Island. Zootaxa 5514 (1): 28-40, DOI: 10.11646/zootaxa.5514.1.2, URL: http://dx.doi.org/10.11646/zootaxa.5514.1.2
242F878AFFC6933DFF38A864001709E2.taxon	type_taxon	Type species. Archaeodiacyclops okhensis sp. nov. Other species. Archaeodiacyclops uruguayensis (Kiefer, 1935) comb. nov.; A. salisae (Reid, 1992) comb. nov.; A. ecabensis (Fiers & Ghenne, 2000) comb. nov.; A. pilosus (Fiers & Ghenne, 2000) comb. nov.	en	Alekseev, Victor, Chaban, Olga (2024): Archaeodiacyclops, new genus with “ archaic ” features (Crustacea, Copepoda, Cyclopoida), with description of new species from water bodies of northern Sakhalin Island. Zootaxa 5514 (1): 28-40, DOI: 10.11646/zootaxa.5514.1.2, URL: http://dx.doi.org/10.11646/zootaxa.5514.1.2
242F878AFFC6933DFF38A864001709E2.taxon	etymology	Etymology. New genus is named using prefix Archae - in reference to a number of “ archaic ” characters in its structure, namely 17 - segmented A 1 (the largest number known in the subfamily), caudal branches with hairs on inner side, as well as unreduced segmentation of swimming legs.	en	Alekseev, Victor, Chaban, Olga (2024): Archaeodiacyclops, new genus with “ archaic ” features (Crustacea, Copepoda, Cyclopoida), with description of new species from water bodies of northern Sakhalin Island. Zootaxa 5514 (1): 28-40, DOI: 10.11646/zootaxa.5514.1.2, URL: http://dx.doi.org/10.11646/zootaxa.5514.1.2
242F878AFFC09337FF38AD9F07030E1E.taxon	description	(Figs. 3 - 6) lsid: zoobank. org: act: 28 ED 8 DB 9 - CD 5 C- 4 B 38 - 9909 - CED 2 EB 41 F 765	en	Alekseev, Victor, Chaban, Olga (2024): Archaeodiacyclops, new genus with “ archaic ” features (Crustacea, Copepoda, Cyclopoida), with description of new species from water bodies of northern Sakhalin Island. Zootaxa 5514 (1): 28-40, DOI: 10.11646/zootaxa.5514.1.2, URL: http://dx.doi.org/10.11646/zootaxa.5514.1.2
242F878AFFC09337FF38AD9F07030E1E.taxon	materials_examined	Type material. Holotype female, mounted on permanent slide, # 55606; paratype male, mounted on permanent slide, # 55607; preserved paratypes: 3 females undissected, # 55608; deposited in Federal Collection of Zoological Institute of Russian Academy of Sciences. Type locality. Russia, North of Sakhalin Island, Sakhalinka river on outskirts of Okha town, under bridge (53 ° 37 ’ 03.4 ” N 142 ° 56 ’ 20.6 ” E).	en	Alekseev, Victor, Chaban, Olga (2024): Archaeodiacyclops, new genus with “ archaic ” features (Crustacea, Copepoda, Cyclopoida), with description of new species from water bodies of northern Sakhalin Island. Zootaxa 5514 (1): 28-40, DOI: 10.11646/zootaxa.5514.1.2, URL: http://dx.doi.org/10.11646/zootaxa.5514.1.2
242F878AFFC09337FF38AD9F07030E1E.taxon	etymology	Etymology. The species is named after the town where it was found.	en	Alekseev, Victor, Chaban, Olga (2024): Archaeodiacyclops, new genus with “ archaic ” features (Crustacea, Copepoda, Cyclopoida), with description of new species from water bodies of northern Sakhalin Island. Zootaxa 5514 (1): 28-40, DOI: 10.11646/zootaxa.5514.1.2, URL: http://dx.doi.org/10.11646/zootaxa.5514.1.2
242F878AFFC09337FF38AD9F07030E1E.taxon	description	Description of female holotype. Female body length without caudal setae 1029 – 1233 μm. Habitus slender, with largest width near posterior margin of cephalothorax (Fig. 2 A). Cephalothorax 1.1 times as long as wide, with maximum width close to posterior margin. Two last thoracic somites laterally slightly produced and curved. Genital double-somite slightly longer than wide, tapering posteriorly, with lateral sharp angles anteriorly (Fig. 2 D); receptaculum seminis with large round anterior part and almost not extended posteriorly; pore-canal short, straight. Hyaline frills of abdominal somites smooth. Anal somite with small thin spinules along posterior margin; anal operculum weakly developed, almost straight (Fig. 3 B). Caudal rami 4.5 – 5.1 times longer than wide, almost parallel (Fig. 2 C); lateral surface smooth except tiny spines at insertion of outermost caudal setae; medial surface with one proximal row of hair-setules and two more posterior rows of tiny spines; dorsal and ventral surfaces are covered with groups of tiny spines poorly visible under low magnification (more abundant on ventral surface) (Fig. 3 A, B). Lateral seta inserted at about posterior 1 / 4 of lateral margin of ramus, without spines at insertion place. Innermost seta 1.3 – 1.4 times as long as outermost seta, and 0.6 times as long as ramus length. Dorsal seta 0.8 – 0.9 times as long as outermost seta. All caudal setae plumose (dorsal setae with only few hairs). Distal setae length ratio beginning from outermost one: 1.0 / 5.5 – 5.9 / 8.0 – 8.3 / 1.3 – 1.4. Antennule (A 1) 17 - segmented, short, not reaching posterior edge of cephalothorax. Setation of antennular segments, beginning from first: 8 / 4 / 2 / 6 / 4 / 2 / 2 / 1 / 1 / 0 / 1 / 1 + ae / 0 / 1 / 2 / 2 + ae / 7 + ae (Fig. 3 C). First segment with one row of spinules. Aesthetasc on 12 th segment reaching 1 / 3 of 15 th segment or distal border of 14 th segment. Aesthetasc on 16 th segment reaching 3 / 4 to 9 / 10 of 17 th segment. Antenna (A 2) composed of basipodite with two medial setae and one long exopodal seta, and three endopodal segments; endopodite setation: 1, 9, 7 (Fig. 5 A). Basipodite ornamentation composed of few sparse proximal groups of spines, rather variable (Fig. 5 B – D); medial setae smooth, exopodal seta covered with short spinules. Mouthparts. Labrum (Fig. 3 D) composed of large plate ornamented with two groups of long setules; distal margin with 10 large blunt teeth between rounded lateral projections. Mandible (Fig. 3 E) composed of coxa and palp bearing three setae (two long plumose and one short naked) as typical for the family; coxal gnathobase with group of long spinules, plumose seta, adjacent shorter seta with two denticles and blunt teeth of different size. Maxillule composed of praecoxa and palp of typical cyclopid structure; setation and ornamentation according to figure 4 B; palp naked. Maxilliped (Fig. 4 C) 4 - segmented as typical for the family; segment setation: 3 / 2 / 1 / 3; second segment ornamented with two lateral rows of spinules and one medial group of spinules; third segment bearing one medial group of spinules. Maxilla (Fig. 4 A) 5 - segmented as typical for the family, with first two segments partly fused, without ornamentation. All swimming legs with 3 - segmented endo- and exopodites; distal exopodite spine formula 3 / 4 / 4 / 4; setal formula according to genus description. In one of specimens, P 4 asymmetrical with 3 spines on one of the Exp 3 and 4 spines on another. All setae of swimming legs not modified, slender and plumose, except distal seta of P 1 Exp 3 which is covered with denticles along outer side and hairs along inner side. P 1 Bas with inner spine, which heterogeneously covered with long setules proximally and short setules distally; this spine reaching distal margin of Enp 2 (Fig. 4 E). P 1 Bas without distal arc of spinules between Enp and Exp frontally. P 1 – P 3 intercoxal plates frontal surface with long hair-setules, caudal surfaces naked. P 1 – P 4 Bas inner outgrowths covered with dense hairs. P 4 Coxa caudal surface ornamented with abundant lateral groups of hair-setules / spinules, and two longitudinal rows of spinules proximally and distally. P 4 intercoxal plate caudal surface with central row of rather long spinules (Fig. 2 F); frontal surface naked. P 4 inner coxal seta homogeneously covered with long hairs; this seta extending beyond inner outgrowth. P 4 Enp 3 1.9 – 2.3 times as long as wide; inner / outer distal spines length ratio 1.0 – 1.1: 1; inner spine 0.7 times as long as segment; distal setae reaching 1 / 2 to 3 / 4 of adjacent spines. P 4 Exp 3 distal spine 0.8 – 0.9 times as long as segment. P 5 two-segmented; proximal segment armed with outer seta; distal segment cylindrical, longer than wide, armed with apical seta and inner spine (Fig. 2 E). Inner spine is almost as long as distal segment (0.9 – 1.2: 1), with several denticles at insertion site. P 5 setae length ratio beginning from inner spine: 1.0 / 2.9 – 3.8 / 2.8 – 3.6. P 6 consists of small plate armed with two short smooth spines and plumose longer outer seta. Male. Habitus shorter and slenderer than in female (Fig. 2 B). Body length 798 μm (paratype). Cephalothorax 1.2 times as long as wide, with maximum width close to posterior margin. Two last thoracic somites without lateral curved extensions. Hyaline frills of abdominal somites coarsely dentate dorsally and ventrally. Caudal rami 4.1 times longer than wide, almost parallel; lateral surface with spines at insertion of outermost caudal setae and tiny denticles at insertion of lateral setae and at proximal third of branch; medial surface with one proximal row of hair-setules and three more posterior rows of tiny spines; dorsal and ventral surfaces are covered with groups and rows of tiny spines poorly visible under low magnification (more sparse than in female). Innermost seta longer than in female, 1.6 times as long as outermost seta, and 0.7 times as long as ramus length. Distal setae length ratio beginning from outermost one: 1.0 / 6.0 / 9.4 / 1.6. Antennule 14 - segmented, with long slender aesthetascs. P 6 with inner spine and two longer plumose setae (Fig. 4 D). P 6 appendages length ratio beginning from spine: 1 / 1.1 / 1.9. Differential diagnosis. Archaeodiacyclops okhensis sp. nov. differs from A. uruguayensis comb. nov., A. ecabensis comb. nov. and A. pilosus comb. nov. in the presence of only one group of long hairs on the inner side of caudal rami, shape of receptaculum seminis, exopodite formula of swimming legs, ratio of distal spines of P 4 Enp 3. A. okhensis sp. nov. is most closely related to A. salisae comb. nov., having a similar habitus, shape of receptaculum seminis, ratio of distal spines of P 4 Enp 3, exopodite formula of swimming legs, the presence of only one group of hairs on the inner side and the absence of a proximal group of spinules on the outer side of caudal rami. A. okhensis sp. nov. differs from A. salisae comb. nov. in the presence of proximal angular projections on genital double-somite, relatively shorter caudal innermost setae, relatively shorter setae of P 4 Enp 3 not reaching tips of adjacent spines, and the presence of hairs on frontal side of P 1 intercoxal plate. For distinguishing species of the new genus, an identification key is provided below.	en	Alekseev, Victor, Chaban, Olga (2024): Archaeodiacyclops, new genus with “ archaic ” features (Crustacea, Copepoda, Cyclopoida), with description of new species from water bodies of northern Sakhalin Island. Zootaxa 5514 (1): 28-40, DOI: 10.11646/zootaxa.5514.1.2, URL: http://dx.doi.org/10.11646/zootaxa.5514.1.2
