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Giesbrecht, 1897

Short description:

Bradyidius armatus is an aetideid calanoid copepod known after both sexes (female 2.65-2.70 mm and male 1.50-2.20 mm). Species known off Norwegian coast, the Norwegian and Barents seas, very probably epibenthic species.

Taxonomic description:

Female. Total length 2.65-2.70 mm. Cephalothorax about 3-4 times longer than abdomen. Rostrum with divergent rami. Posterior corners of Th5 divergent, their points exceeding posterior border of genital segment. Width of genital segment in 1.2-1.3 times more than length. Spermatheca rounded. A1 nearly the same in length as cephalothorax, may reach or exceed posterior border of genital segment. Re1 A2 lacking setae, Re2 A2 with 3 setae. Ri1 Md with 2, Ri2 Md with 9 setae. External spine at Re1 P1 somewhat exceeds the base of following spine. Posterior surfaces of Ri P2-P4 with minute spinules.

Male. (Description after Sars (1902) and Matthews (1964) with modifications). Total length 1.50-2.20 mm. Cephalothorax 3 times longer than abdomen. Points of Th5 posterior corners exceeding posterior border of Abd1. P5 uniramous, left P5 long, 5-jointed, right P5 more than 3 times shorter and 3-jointed, sometimes absent. Its distal joint (third) supplied with 1 terminal and 1 external spine (in all - 2 spines).

Remarks. Boeck (1872) described species of Aetideus under the name Pseudocalanus armatus. Brady (1878) identified as P. armatus Boeck material from England, in which the male was identified correctly, but female attributed to another genus. Giesbrecht (1897) noticed this mistake and proposed for P. armatus sensu Brady (without definition for male or for female) new genus - Bradyidius. In conformity with Article 70c of International Code of Zoological Nomenclature, it is considered that thus Giesbrecht established new species B. armatus Giesbrecht; the fact that Giesbrecht himself did not adduce such combination, contrary to Matthews' opinion (Matthews, 1964) is of no concern. Vanhöffen (1897a) noticed that P. armatus sensu Brady actually attributed to two genera, therefore he rejected name Bradyidius and proposed new name Bradyanus but only for females that were erroneously identified by Brady as P. armatus Boeck. In conformity with the same Article 70c it should be considered that thus Vanhöffen established new species Bradyanus armatus Vanhöffen and this name should be judged as synonym of Bradyidius armatus Giesbrecht, regardless of fact that later Vanhöffen (1897b, 1907) attributed to his species specimens of another species (probably B. similis ).

Vertical distribution:

Probably epibenthic species. Often was found near bottom at depths 36-73 m and over muddy bottoms (Sars, 1902).

Geographical distribution:

Off the coast of Great Britain (Brady, 1878) and of Norway (Sars, 1902; Matthews, 1964; Markhaseva, 1996), Norwegian and the Barents seas (Vervoort, 1952b).

Material examined:

5 females (N 20653) from collections of Zoological Museum of Oslo University (Norway) were studied. Species absent in the collections of the Zoological Institute, St. Petersburg.

Bradyidius armatus