Xenocoeloma brumpti Caullery & Mesnil, 1915

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 : 62-64

Xenocoeloma brumpti Caullery & Mesnil, 1915 .

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 .

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 ) 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.

Figures

FIGURE 27. Xenocoeloma alleni (Brumpt, 1897). A, ectosoma of ovigerous female from Amaeana trilobata; B, ectosoma of ovigerous female from Polycirrus norvegicus caught in Norwegian waters. Xenocoeloma brumpti Caullery & Mesnil, 1915. C. ectosoma of ovigerous female from Polycirrus norvegicus caught in Liverpool Bay. Xenocoeloma orbicularis sp. nov. ovigerous female holotype. D, ectosoma, dorsal view showing paired eggs sacs emerging from common pore; E, same, lateral. Aphanodomus terebellae (Levinsen, 1878) adult female, F, habitus with 1 multiseriate and 1 spent egg sac. Scale bars: A, B, C, F, 1.0 mm; D, E, 0.5 mm.