Mesoparasitic copepods (Copepoda: Cyclopoida) associated with polychaete worms in European seas Author Boxshall, Geoff A. Author O’Reilly, Myles Author Sikorski, Andrey Author Summerfield, Rebecca text Zootaxa 2019 2019-04-09 4579 1 1 69 journal article 27318 10.11646/zootaxa.4579.1.1 a72a13f8-f366-41db-835b-4b42169fd25b 1175-5326 2637477 A4015309-D9B3-4BB7-ABCB-B88A1F8CE5FC Lanassicola bilobatus gen. et sp. nov. Type material : Holotype ovigerous ♀ from tube of Lanassa nordenskjoeldi Malmgren, 1866 , Argus Miljø, Stn 2-2 ( 67° 08.515’N , 15° 24.902’E ), depth 245 m , 12 May 2011 ; collected by A. Sikorski ; NHMUK Reg. No. 2015.466. 2 allotype ♂♂ attached to Holotype female; same locality and habitat data. Differential diagnosis . Adult female ectosoma ( Fig. 19A ) elongate, about 3.5 times longer than maximum width, connected to small bulla inserted within host, via short stalk. Ectosoma dorsoventrally flattened, about 2.79 mm in length and with a maximum width of about 0.8 mm anteriorly, tapering to a width of about 0.5 mm posteriorly. Cephalothorax with paired frontal and anterolateral lobes. Frontal lobes directed slightly anterolaterally, unarmed, probably representing antennules. Anterolateral lobes expanded dorsally ( Fig. 19B ). Posterior margin of ectosoma ( Fig. 19C ) expanded to form median lobe bearing anal slit. Paired genital apertures located ventrally at posterolateral extremities of ectosoma. Cement glands irregularly curved ( Fig. 19C ), up to 0.6 mm in length. Egg sacs multiseriate, about 3.76 mm in length ( Fig. 19A ). Paired antennae located anterior to stalk originating in oral region ( Fig. 19B ); directed medially. Antenna 2- segmented ( Fig. 19D ); proximal segment unarmed, distal segment with paired corrugated adhesion pads. Maxilla ( Fig. 19E ) located posterolateral to stalk; comprising robust proximal segment; distal segment with paired corrugated pads. Male sac-like ( Fig. 20A ), pear-shaped with narrow anterior end and broad posterior extremity, 110 µm in length, with maximum width of 82 µm . Paired antennules located anteriorly on lateral margin, paired antennae located on frontal margin either side of mid-line ( Fig. 20A ). Antennules unsegmented ( Fig. 20B ), tapering, armed with 5 setae along anterior margin and apex. Oral region modified into funnel-like structure located anteriorly on ventral surface. Oral funnel ovoid in ventral view ( Fig. 20C ), enclosing paired spinulate pads. Maxillae similar in structure to those of female, located posterior to oral funnel on ventral surface ( Fig. 20C ). Male producing paired cylindrical spermatophores ( Fig. 20D ) about 30 µm long, each with short tubule. Etymology . The name of the new species, bilobatus , alludes to the presence of two pairs of lobes on the frontal margin of the cephalothorax. Remarks . The adult female of Lanassicola bilobatus gen. et sp. nov . can be distinguished from L. arcticus gen. et sp. nov . by the bilobate frontal margin of the cephalothorax in the former compared to the unilobate condition of the latter. The paired lobes of L. bilobatus gen. et sp. nov . are interpreted as representing antennulary and anterolateral lobes. The body of L. bilobatus gen. et sp. nov . is also larger, so the body length of the adult female is 2.79 mm , compared to 2.19 mm in the type species, and the trunk is thicker and more robust. The adult male of L. bilobatus gen. et sp. nov . is sub-triangular in dorsal view compared to the rounded sac-like trunk of male L. arcticus gen. et sp. nov . The ectosoma was detached from the host and so there is no information on the form of the endosoma, or on the positioning on the host.