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A Contribution to the Life History of Bucephalus longicornutus (Manter, 1954)

Discussion of Cercaria

Discussion of Cercaria

All previous descriptions or reports of bucephalid cercariae known to the author are listed in Table II. Of the descriptions of marine species, only those given by Levinsen (1881), Haswell (1903), Ozaki and Ishibashi (1934), Cole (1935), Chubrik (1952), Hopkins (1954), Cable (1956), Hopkins (1958) and Holliman (1961) are adequate for close comparisons with the present species. Bucephalus crux, B. mytili and the cercaria of Prosorhynchus squamatus described by Levinsen, Cole and Chubrik respectively have a posterior sucker-like extension of the tail stem and are thus quite distinct from the present species; B. margaritae Ozaki and Ishibashi differs in details of spination, the absence of an axial strand and has "dermal gland cells" rather than cystogenous granules distributed through the body; B. sp. Haswell differs in the shape of the intestine and has two slender processes at the anterior end of the body; B. cuculus McCrady, as described by Hopkins (1954), has a flame cell formula of 2 [(2 + 2 + 2) + (2 + 2 + 2)] = 24; the behaviour, spination and granulation, number of lips surrounding the opening of the cystogenous organ pore, and shape and structure of the tail stem of Cercaria caribbea XLII Cable and C. apalachiensis Holliman differ from the present species; B. loeschi Hopkins has a shorter excretory bladder and a smaller intestine.

As stated elsewhere (p. 2) and as can be seen from Table II, many authors have placed cercariae in adult genera without any experimental evidence to substantiate their views. It is therefore recommended that all bucephalid cercariae described as species of Bucephalus or Prosorhynchus without experimental proof be transferred to the group name Cercaria to agree with the usual practice regarding cercariae whose adult status is unsure. Furthermore, as shown by Hopkins (1954), Bucephalopsis can only be used for the cercaria Bucephalopsis haimeanus (Lacaze-Duthiers, 1854). Thus Bucephalopsis modiolae Faust, 1928, must now become C. modiolae (Faust, 1928).

The probable error of many authors in synonymising the cercariae they have found with Bucephalopsis haimeanus has already been referred to (p. 2). This practice is a reflection on the inadequate descriptions that have been given and it is obvious that the majority of different cercariae need re-describing to rectify this situation.