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Waretrematinae subfamily


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Sub-family Waretrematinae

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.

 


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Change Date 13 November 2011

 

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