Family LACISTORHYNCHIDAE Guiart, 1927

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Family LACISTORHYNCHIDAE Guiart, 1927

Introduction

The composition of this family has undergone numerous changes. The most recent arrangement, that of Palm (2004) is followed here. Within the Lacistorhynchidae are included the former families Dasyrhynchidae, Grillotiidae Dollfus, 1969, Hornelliellidae Yamaguti, 1954, Mustelicolidae Dolfus, 1969 and Pseudogilquiniidae Bilqees & Khatoom, 1980. The morphological synapomorphies for the family are the presence of intercalary hook rows or a chainette (Olson et al., ).

Palm (2004) recognised two subfamilies, Grillotiinae and Lacistorhynchinae but the distinction between the two in his key is not clear. As the systematics of this group is in a state of flux, comments are appended for each of the constituent families.

The definition of the family Lacistorhynchidae by Campbell & Beveridge (1994) restricted it to three well known genera, Callitetrarhynchus, Floriceps and Lacistorhynchus. The family was characterised by two bothridia and the possession of a chainette on the external surface of the tentacle. There are six hooks in each principal row, with the sixth hook displaced anteriorly; hooks seven and eight form a linear array, in which hook eight is termed a 'satellite' of hook seven, and the chainette is formed by the ninth hooks from each side of the tentacle. In addition, the male and female genital ducts unite to form an hermaphroditic duct. This definition was greatly expanded by Palm (2004) to include all genera with chainettes or intercalary rows of hooks.

The subfamily Grillotiinae was erected by Dollfus (1942) within the Lacistorhynchidae and was elevated to family status by him in 1969, without definition. The family was formally defined by Campbell & Beveridge (1993). They diagnosed it on the basis of having two bothria and a band of hooks on the external surface of the tentacle (Campbell & Beveridge 1994).

Members of the former family Mustelicolidae are characterised by the possession of two bothria and multiple chainettes on the external surface of the tentacle (Campbell & Beveridge 1994). The family was erected by Dollfus (1969) for a single species, Mustelicola wooodsholei, described from a shark, Mustelus sp. from the eastern coast of the United States. Subsequently, Campbell & Beveridge (1987) described a second species from Mustelus antacticus from Tasmania. However, in a redescription of Diesingium lomentaceum from Mustelus mustelus from Europe, Beveridge & Campbell (1994) showed that Mustelicola a synonym of Diesingium. Beveridge & Campbell (1989) described a new genus and species, Patellobothrium quinquecatinatum, from northern Australian waters. Subsequently, the species was shown to be a synonym of Bombycirhynchus sphaerenaicum described by Pintner (1930) from Sri Lanka. The nomenclature used in this family may, therefore, be potentially confusing. The family Mustelicolidae, nonetheless, remained a valid family until synonymised with the Lacistorhynchidae by Palm (2004).

The former family Hornelliellidae contains a single enigmatic species, Hornelliella annandalei, found primarily in the zebra shark, Stegostoma fasciatum (Stegostomatidae). H. annandalei is characterised by the presence of two bothria and a tentacular armature in which the chainette on the external surface of the tentacle is composed of alternating pairs of hooks. In proglottides, the male and female ducts unite to form an hermaphroditic vesicle (Campbell & Beveridge 1994). The species was redescribed from Australian waters by Campbell & Beveridge (1987).

The Dasyrhynchidae are characterised by two bothria, elongate bulbs, a craspedote scolex, with the tentacular armature of the poeciloacanthous form, that is bearing a chainette on the external surface of the tentacle, with more than eight hooks in the principal rows, and by the possession of an hermaphroditic duct in the proglottis (Campbell & Beveridge 1994). Campbell & Beveridge (1994) included a single genus, Dasyrhynchus Pintner, 1928. Earlier, Dollfus (1942) employed a broader definition which included all genera possessing two bothria and a chainette. The genus was revised by Beveridge & Campbell (1993).

The adults occur in the spiral valves of a variety of shark families while the larval stages or plerocerci are found in the abdominal cavity or in the liver of teleosts.