Bradophila Levinsen, 1878

Boxshall, Geoff A., O’Reilly, Myles, Sikorski, Andrey & Summerfield, Rebecca, 2019, Mesoparasitic copepods (Copepoda: Cyclopoida) associated with polychaete worms in European seas, Zootaxa 4579 (1), pp. 1-69 : 6

Genus Bradophila Levinsen, 1878

Diagnosis. Adult female body highly transformed consisting of ectosoma connected to endosoma by broad stalk passing through host’s body wall. Endosoma embedded in host, elongate, filiform. Ectosoma globular to slightly dorsoventrally flattened; lacking any external trace of segmentation. Genital apertures paired, carried on sclerotized areas of cuticle located posterolaterally on margin of ectosoma; median copulatory pore located between genital apertures on ventral surface of ectosoma. Lacking vestiges of appendages and caudal rami; without anus. Egg sacs paired, large, multiseriate.

Adult male consisting of broad, subquadrate cephalothorax and slender postcephalic trunk. Caudal rami modified as pair of hooks. Antennule indistinctly 3-segmented; third segment offset posterolaterally; first segment with blunt, modified setal element; second segment with 2 setal elements; distal segment with 2 apical elements. Antenna uniramous and subchelate, comprising elongate proximal segment, plus distal endopodal segment bearing terminal claw plus accessory claw. Mandible absent. Maxillule small, lobate, bearing 2 apical setae. Maxilla lobate, ornamented with denticles distally. Maxilliped subchelate; proximal segment robust, ornamented with 2 spinulose processes on myxal surface; distal subchela comprising free endopodal segment plus curved claw.

Type species: Bradophila pygmaea Levinsen, 1878 , by monotypy.

Remarks. Since its original description 140 years ago, the type species, B. pygmaea , has been reported from only a single host species, Brada villosa (Rathke, 1843) , a member of the polychaete family Flabelligeridae de Saint Joseph, 1894. The original description was based on museum material with no locality data ( Levinsen 1878) but its known distribution is restricted to high latitude waters of the North Atlantic including both Norwegian and Russian coastal waters and into the White Sea ( Marchenkov 1999; Huys 2016). Marchenkov (2002) gave supplementary morphological data on the female of B. pygmaea : its globular, slightly flattened ectosoma ranged from 0.5 to 0.7 mm in diameter; the egg sacs were up to 1.2 mm long and varied in width from 0.4 to 0.7 mm; in live specimens the colour of the ectosoma was translucent or milky white. Marchenkov (2002) stressed that the posterolaterally-located, paired genital apertures of the female were relatively inconspicuous. He also described the endosoma as elongate with its entire surface covered with small tubercles and this was confirmed by Huys (2016). However, as noted by Huys (2016), the size of the ectosoma of the female given by Levinsen (1878) was 330–500 µm, which is considerably smaller than that reported by Marchenkov (2002).

The male of B. pygmaea was attached in the vicinity of the stalk of the female by means of its modified caudal rami, antennae and maxillipeds ( Marchenkov 2002). Marchenkov gave the male body length as 0.35 to 0.45 mm, with a maximum width at the cephalosome of 0.15 to 0.20 mm. Huys (2016) examined material of B. pygmaea and described the male as 530 µm in length with a maximum width of 93 µm. The structure and setation of the male limbs were described by Marchenkov (2002), and again more recently by Huys (2016) who corrected several misinterpretations made by Marchenkov (2002).