Herpyllobiidae Hansen, 1892

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 : 9

Family Herpyllobiidae Hansen, 1892

Three genera of Herpyllobiidae , Herpyllobius , Eurysilenium and Phallusiella Leigh-Sharpe, 1926 , were listed as accepted by Boxshall & Halsey (2004) and a fourth, Gottoniella López-González, Bresciani & Conradi, 2006 , was added later ( López-González et al. 2006). The genera Herpyllobius , Eurysilenium , and Gottoniella are valid but there remains considerable uncertainty over the validity of Phallusiella . It was provisionally maintained by Lützen (1964a) but the descriptions of the known species are inadequate by modern standards and possibly inaccurate as well. Phallusiella comprises two species, P. psalliota Leigh-Sharpe, 1926 and P. vera Leigh-Sharpe, 1926 , both described from UK waters off Plymouth ( Leigh-Sharpe 1926). The host of P. psalliota was given as Harmothoe extenuata (Grube, 1840) by Leigh-Sharpe (1926), a known host of Herpyllobius arcticus Steenstrup & Lütken, 1861 . The host of P. vera was given as Malmgrenia castanea (McIntosh, 1876) . The type material could not be traced and, given the lack of any subsequent reports of either of these two species, we consider Phallusiella to be a genus inquirendum and both P. psalliota and P. vera to be species inquirenda.

The genus Thylacoides Gravier, 1912 was not considered by Lützen (1964a) in his review of the family and was overlooked by Boxshall & Halsey (2004). Gravier (1913) considered his genus to be closely related to Eurysilenium and proposed Eurysileniopsis as a replacement name for Thylacoides , because of the latter’s close similarity to Thylacodes which he regarded as already having been used by Guettard in 1774 stating “ce nom a déjà étè employé par Guettard en 1774”. However, Eurysileniopsis Gravier, 1913 is an unnecessary replacement name because Thylacoides , as established by Gravier (1912 a, b), is not a strict homonym of Thylacodes . Gravier’s (1913) detailed description of Thylacoides sarsi Gravier, 1912 (under the name Eurysileniopsis sarsi ) is difficult to interpret. It resembles a herpyllobiid in general form, i.e., in possessing a sac-like body attached to host by stalk (“acetabulum”) which originated in the middle of the underside of the body, but Gravier (1913) described a “buccal complex” located between the origins of the paired egg sacs. We infer, from its size and position on the body, that the “buccal complex” of Gravier probably represents the paired genital apertures, possibly with males attached. The host of T. sarsi was a syllid polychaete, Trypanosyllis gigantea (McIntosh, 1885) , and only polynoid and aphroditid worms are currently known to serve as hosts for members of the Herpyllobiidae . In the absence of new material we treat Thylacoides sarsi as a species inquirendum, and its affinities with the Herpyllobiidae are in need of confirmation.