Lester R. G. Cannon

On neotropical Temnocephala (Platyhelminthes)

Fourteen of the 19 recorded species of neotropical Temnocephala are re-examined for new taxonomic characters and all records are tabulated. Autapomorphies found are eyespots with red, fugacious pigment, a characteristic pattern of syncytial epidermal plates and excretory pores enclosed within the boundaries of the paired post tentacular (‘excretory’) plates. The worms are rather homogeneous with regard to the genital structures (although T. brenesi has only one pair of testes) and appear to hold their tentacles in a consistent pattern. This suite of species is homogeneous, differing from worms from Australia currently assigned to the genus. Since the type of the taxon Temnocephalida, Temnocephala chilensis (Moquin-Tandon, 1846), has the suite of characters shown here, a new genus (Temnosewellia gen. nov.) is proposed to accommodate Australian representatives formerly in Temnocephala.

Hysterothylacium, Iheringascaris and Maricostula new genus, nematodes (Ascaridoidea) from Australian pelagic marine fishes

The state of knowledge of Australian fish parasitic ascardioids is briefly reviewed. The following species are described in full: Hysterothylacium cornutum, H. pelagicum, H. scomberoidei n. sp. Additional data are provided for Iheringascaris inquies. Maricostula n. gen. is established for those species that have lips with lateral flanges, deep postlabial grooves, interlabia, and elongate intestinal caecum, pyriform ventriculus, long sac-like ventricular appendix, an expanded filamentar excretory system and excretory pore near the nerve ring. The males of all the species have precloacal crests. Species included are: M. caballeroi (Deloya), M. cenatica n. sp., M. histiophori (Yamaguti), M. incurva (Rudolphi), M. makairi n. sp. and M. tetrapteri n. sp. All are recorded from billfishes, and all but M. caballeroi are recorded from Australian waters. The systematic position of the genus is discussed. New characters of taxonomic utility used in the discrimination of fish parasitic ascaridoids are discussed. Thes...

Endosymbiotic Umagillids (Turbellaria) from Holothurians of the Great Barrier Reef

Seven new species of umagillid turbellarians from the intestine of aspidochirote holothurians of the Great Barrier Reef are described: Cleistogamia heronensis sp.n., C. longicirrus sp.n., C. pulchra sp.n., C. pallii sp.n., C. pyriformis sp.n. and Wahlia stichopi sp.n. as well as Paranotothrix queenslandensis gen.n. sp.n. The new genus is recognized as distinct from Notothrix Hickman, 1955 because the female system lacks a bursal valve, a significant characteristic within the Umagillidae. Examination of this and other characteristics of the family reveal that the division of the family by Stunkard & Corliss in 1950 into the sub‐families Collastominae Wahl, 1910, Bicladinae Stunkard & Corliss, 1950 and Umagillinae Wahl, 1910 is supported; further, within the Umagillinae, four subgroups may be recognized: within holothurians are (i) the Cleistogamia group with a secondary uterus, within this group Ozametra elegans and O. striata are placed in Seritia gen.n. differing from Ozametra by the presence of both a bursal valve and a cuticular stylet, (ii) the Anoplodium group with a single ovary and a muscular (not cuticular) male intromittent organ and (iii) the Umagilla group in which Monticellina longitubu becomes a junior synonym of U. forskalensis; within echinoids (iv) the Syndesmis group in which Syndisyrinx is recognized a valid genus for those worms with a bursal valve and Syndesmis for those lacking this structure. Marcusella is suppressed. A visual key based upon presumed primitive and derived states is given as is a full host check list of the Umagillidae.

Temnocephalan symbionts of the freshwater crayfish Cherax quadricarinatus from northern Australia

Four species of turbellarian temnocephalan symbionts (Platyhelminthes: Temnocephalida) are reported for the first time from the external surfaces of Cherax quadricarinatus, a freshwater crayfish from northern Australia. Three of these species — Temnocephala rouxii Merton, 1913, Notodactylus handschini (Baer, 1945), and Diceratocephala boschmai Baer, 1953 — are known previously from related crayfish in New Guinea. The newly discovered fourth species, Decadidymus gulosus n. gen., n. sp., has an unusual combination of characters linking it with both the Temnocephalidae and the Scutariellidae. Together the four species possess an array of characters that challenges current concepts of families in the order. D. boschmai has an almost completely ciliated epidermis, a feature otherwise unknown in the order.

Stylochus (Imogene) matatasi n. sp. (Platyhelminthes, Polycladida): pest of cultured giant clams and pearl oysters from Solomon Islands.

A large polyclad flatworm has been consistently found associated with mortalities of the cultured giant clam,Tridacna gigas (L.) and the fouling pearl oysterPinctada maculata (Gould) in Solomon Islands.Stylochus (Imogene) matatasi n. sp. is described and a brief account of its biology is given.

Comparative ultrastructural studies of the epidermis, sperm and nerve fibres of Cleistogamia longicirrus and Seritia stichopi (RhabdocoeIa, UmagiIIidae)

The epidermis of Cleistogamia longicirrus consists of columnar, interdigitated cells with apical mitochondria, short microvilli and cilia which have a single horizontal rootlet anchored in the adjacent cytoplasm by transverse bars and a thin side branch. Cells are held together by desmosomes and intermediary junctions. Epidermal cilia have a terminal, electron dense rod between the central microtubules and doublet 1 and a terminal plate; doublets 1 and 6–9 lose one of their microtubules and gradually all doublets lose one microtubule and peripheral doublets disappear. Spermatozoa have a single closed peripheral row of microtubules, numerous electron dense granules and mitochondria and axonemes are of the 9 +“1” type and free for most of their length. Nerve fibres have microtubules and some nerve fibres are surrounded by lamellae and have invaginations of the fibre wall. The epidermis of Seritia stichopi resembles that of Cleistogamia, but cilia have a single horizontal rootlet anchored by transverse bars in the cytoplasm, without a side branch. Spermatozoa also are similar to those of Cleistogamia. Certain ultrastructural similarities between some Umagillidae and Neodermata are apparently due to convergent evolution and do not allow the conclusion that Umagillidae and Neodermata are particularly closely related.

The importance of the fixation of colour, pattern and form in tropical Pseudocerotidae (Platyhelminthes, Polycladida)

At last a fixation method that ensures tropical pseudocerotid polyclads are fixed flat, preserved for histological preparation and which also retains their colour pattern has been developed. FCA-PGPP (Formaldehyde Calcium Acetate-Propylene Glycol, Propylene Phenoxetol) fixative is frozen and worms are coaxed onto filter paper which is then laid on the frozen fixative. As a consequence, over 230 species have been documented from the southern Great Barrier Reef and eastern Papua New Guinea (Newman & Cannon, 1994; in press). It was determined that species diagnoses need to be based on colour pattern, general morphology of living animals and serial reconstructions of the male anatomy.

The occurrence, spectral properties and probable rôle of Haemoglobins in four species of entosymbiotic turbellarians (Rhabdocoela: Umagillidae)

Abstract Physiologically active intracellular haemoglobins have been identified, localized and characterized histo-chemically and spectroscopicaily in the umagillid rhabdocoels Cleistogamia longicirrus, C. heronensis, Seritia stichopi and Paranototbrix queenslandensis, entosymbiotic in aspidochirote holothurians from reef flats on the Great Barrier Reef. In C. longicirrus, from the anterior and mid guts of Stichopus chloronotus, S. borrens and S. variegates, the pigment is confined to parenchymal cells around the brain and pharynx, and to the pharyngeal musculature. It also occurs at these sites in C. heronensis from the same, gut regions of Holotburia leucospilota; mature C. heronensis additionally have large quantities around the ovary and secondary uterus. S. stichopi, from the anterior and mid guts of S. chloronotus, S. borrens and S. variegates has a virtually uniform distribution of haemoglobin throughout the parenchyma and pharyngeal and subepidermal musculatures. In P. queenslandensis, from the po...

On the phylogeny of families and genera within the Temnocephalida

Temnocephalida includes species demonstrating many intermediate steps presenting the transition from commensalism to parasitism. Dramatic morphological changes also occurred within this group but the number of supraspecific taxa is small, making the Temnocephalida an excellent model for evolutionary studies. Having summarised original and relevant published morphological data, we suggest a cladogram (phylogenetic tree) which nearly fully resolves the order of branching of families and main genera within the Temnocephalida. We also introduce a new family, the Diceratocephalidae nov. fam.

Organisation of the epidermal syncytial mosaic in Diceratocephala boschmai (Temnocephalida: Platyhelminthes)

The epidermis of Diceratocephala boschmai Baer, 1952 (Temnocephalida : Platyhelminthes) was studied using silver-nitrate staining and electron microscopy. The epidermis consists of six syncytia separated by lateral membranes: the frontal, trunk, stalk, adhesive disc syncytia, and a pair of post-tentacular syncytia. Neighbouring syncytia differ in many characters including (1) the presence or absence of locomotory cilia, (2) the degree of the differentiation of the apical cytoplasm layer, (3) the presence or absence of bundles of cytoskeletal filaments, imaginations of basal membrane and other specialised cytoplasmatic structures, (4) the abundance of hemidesmosomes at the basal membrane, and (5) the abundance and nature of gland ducts penetrating the syncytium. These structural differences reflect functional differences between the syncytia. Thus, multisyncytial organisation of the epidermis may be explained by functional differences between the syncytia. Only between the frontal and trunk syncytia has no apparent ultrastructural difference been found.