Bradyidius Giesbrecht, 1897
Taxonomic description:
Female. Body length 1.59-4.50 mm (for B. tropicus only once recorded, 1.2 mm (Wolfenden, 1905)). Cephalothorax 3-4 times longer than abdomen. Crest absent. Rostrum present; robust, bifurcate, with divergent or (rarely) non-divergent rami. Cephalon and Th1 completely or incompletely fused, line of separation often visible, Th5 and Th4 fused, but line of fusion also often visible. Posterior corners of Th5 prolonged into points (spikes) not separated from segment, usually covering first third of genital segment, but may be longer and even exceeding posterior border of genital segment. Length and width of genital segment nearly equal, sometimes longer than wide (or wider than long); this segment is usually more than twice as long as following segment. Abd1-Abd3 with little spinules along posterior border. A1 24-segmented, exceeding Th3, as long as cephalothorax or even longer; many segments of A1 supplied with long setae and aesthetascs. Re A2 nearly 1.2 times longer than Ri A2; coxopodite bears 1, basipodite with 2, Ri1 A2 with 2, Ri2 A2 with 6-8 setae (usually in combination 6 terminal and 1 posterior) at external lobe; Re1 A2 lacking setae or there is 1 seta, Re2 A2 with 2-3 setae; Re3-Re6 A2 with 1 long seta each, Re7 with 1 seta placed near the middle of segment or removed to its distal part and 3 terminal setae. Md palp base with 2 (B. hirsutus with 1) setae, Ri1 Md with 2-3, Ri2 Md with 9, rarely 8 or 11 terminal and often 1-2 small posterior setae. On Mx1 gnathobase 9 terminal setae, most of claw-like configuration, in addition there is often 1 thinner and shorter seta, on posterior surface 3-4 setae, also often small teeth (near the bases of these setae) and hairs; second internal lobe with 5, third with 4 setae, at protopodite near the base of Ri 5, at Ri 13, 15-17 setae, at Re 10 setae, at external lobe 7 long and 2 short thinner setae. Mx2 typical of Aetideidae, at fourth and fifth endites 1 of setae thickened into claw-like. Mxp typical of family: protopodite in its proximal part usually with 1 seta, than there are 3 groups of setae (looking from proximal to distal part of segment); proximal group contains 2 (rarely 1) setae, in the middle 3, and distally 3 setae; Ri1 Mxp with 3 medial setae, nearly 1.2-1.3 times longer than protopodite. P1 with 3-segmented Re each segment supplied with external spine, external spine at Re2 P1 usually significantly thicker than the same at Re1 P1, Ri one-segmented, external lobe well developed. P2 with 2-segmented Ri and 3-segmented Re, P3-P4 rami 3-segmented. Posterior surfaces of Ri P2-P4 often covered with surface minute spinules. External spines at Re2-Re3 long, longer than in other genera of Aetideidae. P1-P4 coxopodites often with groups of surface spinules.
Male. Body length 1.19-3.30 mm. Cephalothorax about 2.4-3.0 times longer than abdomen. Crest absent. Rostrum nearly as in females, but its rami usually not so divergent, may be nearly parallel. Cephalon and Th1, as well as Th4-Th5 fused, rarely line of fusion visible. Points of posterior corners of Th5 short, reaching, or even exceeding posterior border of genital segment. Abd2 at least twice as long as genital segment. Caudal rami 1.3-1.4 times longer than wide. A1 21-24-segmented on the left and 20-24-segmented on the right, they may be shorter: to the end of Th2, or much longer, even reaching caudal rami. Setation of Re1-Re2 A2 in comparison with female rudimental, Md gnathobase reduced, also partly reduced setation of Md palp, protopodite Mxp usually with only 2 distal setae. Mx1 also with partly rudimental setation, Mx2 like Mx1 rather reduced. P1-P4 with segmentation and structure as in female, only spines at Re P1 may be considerably shorter. P5 of "simple" structure, uni- or biramous, usually of the same length; if uniramous usually about equal in length, but right may be 3 times shorter. If P5 biramous, Ri one-segmented (rarely 2-segmented) usually styliform. In comparison with abdomen, length of P5 may be different: shorter, or even twice as long.
Type species: Bradyidius armatus Giesbrecht, 1897, by monotypy.
The genus Bradyidius includes 15 species. Description of B. tropicus (Wolfenden, 1905) that remained inaccessible, and B. hirsutus , B. plinoi , B. spinifer and B. styliformis recorded of the southern hemisphere are not given here.
Bradyidius angustus (Tanaka, 1957)(female unknown)
Bradyidius arnoldi Fleminger, 1957
Bradyidius armatus Giesbrecht, 1897
Bradyidius curtus Markhaseva, 1993
Bradyidius luluae Grice, 1972
Bradyidius pacificus (Brodsky, 1950)
Bradyidius rakuma (Zvereva, 1977)(male unknown)
Bradyidius saanichi Park, 1966
Bradyidius similis (Sars, 1902)
Bradyidius subarmatus Markhaseva, 1993