Subfamily Waretrematinae Srivastava, 1937
The waretrematines are differentiated from the other haploporids by their pretesticular uterus,
extensive vitelline follicles in the hindbody, delicate tegument, and sac-like external seminal vesicle.
Waretrematinae includes about 40 known species in 10 genera:
Waretrema Srivastava, 1937
Carassotrema Park, 1938
Pseudohapladena Yamaguti, 1952
Skkjabinolecthum Belous, 1954
Platydidymus Overstreet and Curran, 2005
Conohelmins Fischthal and Nasir, 1974
Elonginurus Lu, 1995
Pholeohedra Cribb, Pichelin, and Bray, 1998
Intromugil Overstreet and Curran, 2005
Culuwiya Overstreet and Curran, 2005
The majority of waretrematines have been found to occur in mullets. From this information, it is hypothesed that the ancestral
host for this subfamily is a mugilid. Species found in non-mugiliformes (i.e., Cyprinidae and Scatophagidae) are suspected to
be acquired by these non-mullet hosts secondarily. Patterns of radiation into non-mullets will help to determine if host
utilization is confined more by host phylogeny or ecological association. Manter (1963) proposed that the mullets, being equally
at home in fresh and marine water, may provide the pathway for marine species to invade the fresh water aquatic environment and for aquatic
species to invade marine hosts. While most waretrematines are found in mullet, determining how those not found in mullet came
to be colonized is fundamental to understanding radiation of species in the waretrematines.
Physiological & Morphological Characters of Mugilidae
Many waretrematine genera have members that are poorly described, and undoubtedly many
species remain to be described. With the exception of Conohelminis and Pholeohedra, most the species in each genus infect
mullets (Mugilidae). The center of diversity of this group appears to be in the Indo-Pacific, with Culuwiya and Intromugil
restricted to the Americas and one species of Conohelmins to the Atlantic Ocean. The affinity of the sub family for mullets,
which are mostly estuarine fishes, makes this group an interesting subject to study radiation. Because the main host fishes
often move freely between fresh and marine environments, there are many opportunities for this group to colonize new fishes
in fresh and marine environments. Carassotrema, for example, has been very successful in Asian cyprinids. Yet, in other
genera that also infect estuarine fishes, members seem to have not been able to make the jump to an entirely freshwater
life history. But, this assumption could also be an artifact of limited sampling, because certainly none is as successful
in freshwater as Carassotrema.
Members of the Mugilidae exhibit several morphological/physiological features that are apparent to the practiced handler of fishes.
Mugilidae have an unusual digestive apparatus in that there is a separate muscular organ, analogous to the 'gizzard' of a bird,
within the digestive pathway. North American Mugil sp. have a peculiar thin black membrane which lines the coelom, and can be
stripped away by friction during evisceration. Mullets are a very 'oily' fish, and if cooked by baking or broiling, will express
that oil in quantity. There is some proteinaceous component of the flesh of Mugil cephalus (North America) that precludes storage by
freezing. Even short-term storage of three days will cause change in the consistency and chemical taste of the flesh of the mullet.
These traits, peculiar as a group to the Mugilidae, very likely reflect in some manner the host specificity displayed by members of
the subfamilt Waretrematinae.