Aetideopsis Sars, 1903
Taxonomic description:
Female: Total length 1.96-4.00 mm. Cephalothorax 2.7-4.0 times longer than abdomen. Cephalon and Th1 completely or incompletely fused, Th4 and Th5 separated, sometimes incompletely (A. armata ). Rostrum always present: bifurcate, may be small with close spaced rami (A. armata ), well developed with heavily sclerotized rami parallel (A. antarctica ) or more or less divergent. In some species near rostrum or at the level of A2 there is slightly elevated crest. Th5 and genital segment symmetrical. Posterior points of Th5 not separated from segment, covering first third of genital segment, reaching its middle length or exceeding it. Body surface may be of "dotted structure" but this feature is not of taxonomic value, as some authors noted, because it may be present or not in one species. Abd1- Abd3 with little spinules along posterior border. Genital segment 1.5 times longer than following segment or may be equal to it; genital segment 1.2-1.6 times longer than wide. Caudal rami 1.3-1.5 times longer than wide. A1 24-segmented, extending posterior border of Abd3 and may reach the end of the body, or even be longer than body (A. retusa ). Re A2 somewhat longer than Ri (1.2-1.5 times). Coxopodite A2 with 1 seta, basipodite with 2, Ri1 A2 with 2 (rarely with 1) setae, Ri2 A2 with 13-15 setae: 5 long and 3 short at internal and 6 long terminal and 1 short posterior at external lobe. Re1 A2 lacking setae, Re2 A2 with 2 setae (1 medial and 1 distal), sometimes medial seta absent (A. armata , A. multiserrata ), each segment of Re3-Re6 A2 with strong long seta, Re7 A2 with 1 medial and 3 terminal setae. Re Md longer than Ri. Md palp base with 2 seta (Bradford (1969a) recorded - 1), Ri1 Md with 3 setae, sometimes there are 2 (A. carinata , A. antarctica ), Ri2 Md with 9-10 setae, commonly with 8 terminal setae arranged in row and 1 (rarely 2) posterior setae. Mx1 with 9 terminal claw-like and 1 thin anterior setae at gnathobase and 4 setae on its posterior surface; second and third internal lobes with 5 and 4 setae respectively, at protopodite near the base of Ri - 5 setae (4 thin and 1 thicker one), Ri with 13 setae, Re with 8-10 setae and external lobe with 7 long and 2 shorter setae. Mx2 typical of Aetideidae, at fourth and fifth endites one of setae thickened into claw-like. Mxp with protopodite 1.1-1.6 times shorter than Ri1 Mxp, setation typical of the family, in A. armata there is a small seta near the base of the segment, all other species lacking the seta, towards distal part of segment there are groups of 2, 3 and 3 setae; in proximal part of protopodite sometimes there is more (A. carinata ) or less (A. rostrata , A. retusa ) developed lamelliform projection. Re P1 3-segmented, each segment with an external spine; these spines may be short, not reaching the middle of next segment (A. cristata ), extending the middle of following spine or somewhat exceeding it. Ri P1 one-segmented with external lobe with minute spinules apically, in A. tumorosa such lobe absent. P2 with one-, or incompletely 2-segmented Ri (often line of separation visible); Re 3-segmented, P3 with 2-segmented Ri (usually 3-segmented, but separation may be incomplete), Re P3 3-segmented; P4 with 3-segmented rami. External side of coxopodites of swimming legs in most species with groups of spinules. Some specimens of A. minor with vestigial P5.
Male: Total length 2.40-4.20 mm. Cephalothorax 2.5-3 times longer than abdomen. Cephalon and Th1 fused, Th4-Th5 incompletely or completely separated. Crest absent. Rostrum less developed than in female of the same species, rami may be spaced closer (A. armata ) or more. Genital segment is at least twice as long as next segment. Points of Th5 posterior corners shorter than in females, may not reach, reach or exceed posterior border of Abd1. A1 23-segmented, shorter than in female or reaching Th3-Th4. A2 like in female, but setation slightly reduced, coxopodite with 1 seta or it is absent, basipodite with 2 setae, at Ri1 A2 1-2 setae or they are absent, Ri2 A2 with 12-14 setae, Re1 A2 lacking seta, Re2 A2 with 1 seta. Md palp base with 1 seta or it is absent, Ri1 Md with 1 seta, Ri2 Md with 9 (in A. tumorosa with 8). Setation of Mx1 is reduced in comparison with female, Ri with 9-11 setae, Re with 9-10 setae. Mx2 reduced. At Mxp protopodite medial setae usually absent, if present with 1-3 very small ones; distal part of segment with 1-2 setae, Ri1 with 3 medial setae. P1 with 3-segmented Re, external spines present at each segment, they differ in length in different species: may not reach base of following spine, or exceed its base. P2-P4 in segmentation and setation like in females. P5 as long as abdomen or longer; biramous, Ri one-segmented; right Re 2-segmented, left Re 3-segmented, of simple structure. After the revision of genus 10 species considered to be valid, all cases of synonymy discussed below.
Type species: Aetideopsis rostrata Sars, 1903, by subsequent designation (Brodsky, 1950).
Genus Aetideopsis includes 10 species. The antarctic species A. antarctica (Wolfenden, 1908) is not included in this work.
Aetideopsis albatrossae Shih and Maclellan, 1981 (male known in copepodid stage V)
Aetideopsis armata (Boeck, 1872)
Aetideopsis carinata Bradford, 1969
Aetideopsis cristata Tanaka, 1957
Aetideopsis minor (Wolfenden, 1911) (male unknown)
Aetideopsis multiserrata (Wolfenden, 1904)
Aetideopsis retusa Grice and Hulsemann, 1967
Aetideopsis rostrata Sars, 1903
Aetideopsis tumorosa Bradford, 1969.