Xenocoeloma brumpti Caullery & Mesnil, 1915

Xenocoeloma brumpti Caullery & Mesnil, 1915 View in CoL .

Material examined: 4 ovigerous ♀♀ from Polycirrus norvegicus , Liverpool Bay, Unicomarine 18443 Stn M10, ( 53° 31’N, 03° 31’W), depth unknown, 0 5 September 1996. NHMUK Reg. Nos 2018.183-186. 2 ovigerous and 2 mature ♀♀ from Polycirrus sp., Liverpool Bay , CEFAS (Unico 29118 CEFLBY), ( 53.5217°N, 03.52147°W), depth unknown, September 2002 GoogleMaps .

Descriptions. Four ovigerous females from P. norvegicus were measured: mean ectosoma length was 2.29 mm (range 1.69 to 2.93 mm), mean maximum width of ectosoma ( Fig. 27C View FIGURE 27 ) was 0.63 mm (range 0.50 to 0.75 mm); mean L:W ratio 3.66 (range 3.42:1 to 3.90:1). The egg sacs are multiseriate, slightly curved and up to 2.4 mm long for largest adult female ( 2.93 mm ectosoma length).

Remarks. The material from P. norvegicus is tentatively attributed to X. brumpti solely on the basis of the L:W ratio of the ectosoma: the mean ratio was 3.66:1. This is less than 4.0:1, the lower limit of the range given by Caullery & Mesnil (1915, 1919). The range exhibited by specimens here attributed to X. brumpti was 3.42 to 3.9:1 and it is effectively contiguous with the range of 1.75:1 up to 3.39:1 found here for X. alleni . Now that larger samples from a wider range of hosts have become available for study, we find that there is no clear gap between the two species in the L:W ratio. Our dividing line between X. alleni (L:W ratio less than 3.40:1) and X. brumpti (more than 3.40:1) is arbitrary. As commented for X. alleni above, morphology based identifications such as these should be regarded as in need of validation once molecular diagnostics become available.