Two new American species of Aberrapex (Eucestoda: Lecanicephalidea: Aberrapecidae) from myliobatid stingrays (Batoidea: Myliobatidae)

Here I describe Aberrapex panamensis sp. nov., a parasite of the rough eagle ray Aetomylaeus asperrimus from the eastern Pacific coast of Panama, and Aberrapex catarinensis sp. nov., found in Myliobatis goodei off southern coast of Santa Catarina, Brazil. Aberrapex panamensis sp. nov. is the second record of Aberrapex Jensen, 2001 for the eastern Pacific Ocean and A. catarinensis sp. nov. is the fifth species of the genus registered in southwestern Atlantic Ocean. The two new species are morphologically distinct from all their congeners. Aberrapex panamensis sp. nov. and A. catarinensis sp. nov. can be distinguished from the majority of their congeners by the microthrix pattern on the scolex surface, number of proglottids and testes, length and width of the scolex, uterus extension, and presence and extension of an external seminal vesicle. The description of these two new species of lecanicephalideans expands the knowledge of this cestode order, with A. panamensis sp. nov. being the third species of the genus reported from Aetomylaeus Garman, and A. catarinensis sp. nov. being the sixth species of Aberrapex reported from Myliobatis Cuvier.

Onchobothrium malakhovi n. sp. (Cestoda: Onchoproteocephalidea) ex Bathyraja (Arctoraja) sexoculata (Rajiformes: Arhynchobatidae) from Kuril Islands (Russia), with comments on the status of the genus Onchobothrium

Onchobothrium malakhovin. sp. was found in the spiral valve of the softnose skate Bathyraja (Arctoraja) sexoculata off the Simushir Island (Kuril Islands, Russia). The new species has bothridia with three loculi and no additional suckers on bothridia, single-toothed hooks unconnected by their bases, no spines at the bases of the hooks, dense matrix around the hook bases shaped as an unpaired butterfly wing, and a short and wide ovary. Onchobothrium malakhovin. sp. differs from O. antarcticum and O. magnum in having a smaller total length, cirrus sac and ovary, smaller testes and eggs. Additionally, the new species differs from O. antarcticum by the absence of a vaginal sphincter and shorter bothridia; differs from O. magnum in having fewer proglottids and smaller vitelline follicles. It differs from O. farmeri, O. convolutum, and O. pseudouncinatum, by the absence of a small spine at the base of the hooks and the absence of accessory suckers on bothridia; from O. pseudouncinatum, additionally, by unconnected hooks; from O. schizacanthium, by the number of testes and by the presence of a postvaginal group of testes. Onchobothrium malakhovin. sp. was placed among other members of the Onchoproteocephalidea with a high support based on the sequence data for the D1-D3 region of the 28S rDNA and cox1 gene. The phylogenetic position of the genus Onchobothrium sensu lato remains ambiguous. We suggest that Onchobothrium sensu lato is a complex genus containing at least two morphologically different groups of species. Onchobothrium farmer, O. convolutum, O. schizacanthium, and O. pseudouncinatum, for which there are no molecular genetic data, are considerably different morphologically from O. malakhovin. sp., O. antarcticum, and O. magnum. A new genus might have to be established for the latter three species after the accumulation of genetic data.

First Report of Lecanicephalidean Tapeworms (Eucestoda) from Freshwater, Including Description of Three New Species of Tetragonocephalum Shipley and Hornell, 1905

The lecanicephalidean cestodes parasitizing the spiral intestine of the endangered giant freshwater whipray, Urogymnus polylepis (Bleeker), are investigated for the first time. Eight host specimens were collected between 2002 and 2008 at 2 collecting sites off the eastern coast of Borneo: 6 from the Kinabatangan River (Malaysia) and 2 from a fish market in Tarakan (Indonesia). Two of these individuals were found to be infected with a total of 3 new species of TetragonocephalumShipley and Hornell, 1905. Tetragonocephalum georgei n. sp. and Tetragonocephalum opimum n. sp. were recovered from a host specimen from the Kinabatangan River, and Tetragonocephalum levicorpum n. sp. was found parasitizing a host specimen purchased at a fish market in Tarakan. Specimens of each of the new species were prepared for light microscopy; specimens of 2 of the new species were prepared for scanning electron microscopy, and histological sections were prepared for 1 of the new species. The 3 new species are distinct from the 9 valid species of Tetragonocephalum and the 1 species inquirendum based on, for example, total length, number of proglottids and testes, and size of the scolex and acetabula. Tetragonocephalum georgei n. sp. and T. levicorpum n. sp. are unusual among their congeners in that they are euapolytic (i.e., gravid proglottids were not observed) rather than apolytic. They differ from one another in scolex and acetabula size. Tetragonocephalum opimum n. sp. is unusual among its congeners in its possession of vitelline follicles arranged in 2, rather than 3, regions in the proglottid. These new species increase the total number of valid species of Tetragonocephalum to 12 and the total number of known cestodes from U. polylepis to 13 species across 6 genera in 4 orders. This is the first account of lecanicephalideans reported from freshwater. The taxonomic status of each of the 32 nominal taxa historically associated with Tetragonocephalum is re-assessed. Type host identities of all valid species are revised and discussed in light of recent taxonomic efforts in the Dasyatidae Jordan and Gilbert.

Morphological variation in the hyperapolytic lecanicephalidean species Anteropora japonica (Yamaguti, 1934) (Eucestoda)

In November of 2013, a specimen of Japanese sleeper ray, Narke japonica (Temminck et Schlegel), caught off Nanfang-ao, Taiwan was found to be parasitised by the cestode Anteropora japonica (Yamaguti, 1934). Specimens comprised whole worms and free proglottids, both of varying degrees of maturity. This material allowed for the opportunity to examine in detail the developmental progression of this hyperapolytic lecanicephalidean species with regard to overall size, scolex dimensions, and microthrix pattern. Complete immature worms ranged in size from 2.4 mm to 14 mm. The smallest scoleces were half as wide as larger scoleces and exhibited a much smaller ratio of apical organ width to bothridial width. Proglottids more than quadrupled in length during maturation from terminal attached immature to detached proglottids. In addition, a change in microthrix pattern was observed on the anterior region of the proglottids from immature to gravid proglottids; the anterior region of attached immature proglottids is covered with gladiate to coniform spinitriches with capilliform filitriches only rarely visible, whereas this region in detached proglottids is covered with gladiate to coniform spinitriches and conspicuous capilliform filitriches. This is the first report of A. japonica from outside Japan expanding its distribution south to Taiwan. In addition, a preliminary phylogenetic analysis of the genus is presented that suggests congeners from the same host species are not each other's closest relatives, nor is there an apparent phylogenetic signal for apical organ type or reproductive strategy (apolysis). However, reproductive strategy does seem to be correlated with host group such that euapolytic species parasitise dasyatid stingrays while hyperapolytic species parasitise either torpediniform rays or orectolobiform sharks.

When proglottids and scoleces conflict: phylogenetic relationships and a family-level classification of the Lecanicephalidea (Platyhelminthes: Cestoda)

This study presents the first comprehensive phylogenetic analysis of the interrelationships of the morphologically diverse elasmobranch-hosted tapeworm order Lecanicephalidea, based on molecular sequence data. With almost half of current generic diversity having been erected or resurrected within the last decade, an apparent conflict between scolex morphology and proglottid anatomy has hampered the assignment of many of these genera to families. Maximum likelihood and Bayesian analyses of two nuclear markers (D1-D3 of lsrDNA and complete ssrDNA) and two mitochondrial markers (partial rrnL and partial cox1) for 61 lecanicephalidean species representing 22 of the 25 valid genera were conducted; new sequence data were generated for 43 species and 11 genera, including three undescribed genera. The monophyly of the order was confirmed in all but the analyses based on cox1 data alone. Sesquipedalapex placed among species of Anteropora and was thus synonymized with the latter genus. Based on analyses of the concatenated dataset, eight major groups emerged which are herein formally recognised at the familial level. Existing family names (i.e., Lecanicephalidae, Polypocephalidae, Tetragonocephalidae, and Cephalobothriidae) are maintained for four of the eight clades, and new families are proposed for the remaining four groups (Aberrapecidae n. fam., Eniochobothriidae n. fam., Paraberrapecidae n. fam., and Zanobatocestidae n. fam.). The four new families and the Tetragonocephalidae are monogeneric, while the Cephalobothriidae, Lecanicephalidae and Polypocephalidae comprise seven, eight and four genera, respectively. As a result of their unusual morphologies, the three genera not included here (i.e., Corrugatocephalum, Healyum and Quadcuspibothrium) are considered incertae sedis within the order until their familial affinities can be examined in more detail. All eight families are newly circumscribed based on morphological features and a key to the families is provided. Aspects of morphological evolution and host associations are discussed in a phylogenetic context for each family and for the order as a whole. Lecanicephalidean genera lacking apical structures were confirmed as the earliest diverging lineages. Proglottid anatomy was determined to be much more conserved and indicative of phylogenetic affinities than scolex morphology. Collectively, the Lecanicephalidea parasitize three of the four orders of Batoidea-their almost exclusive absence from skates (Order Rajiformes) appears to be real; only a few records from sharks exist. At the family level, the breadth of host associations is correlated with taxonomic diversity of the family. The degree to which factors such as intermediate host use or host specificity at any stage in the life-cycle shape these patterns is currently unknown.

A new genus and two new species of lecanicephalidean tapeworms from the striped panray, Zanobatus schoenleinii (Rhinopristiformes: Zanobatidae), off Senegal

Recognised for their diversity in apical structure morphology, members of the cestode order Lecanicephalidea Wardle et McLeod, 1952 known to date exhibit relatively mundane and uniform acetabular morphology. A new lecanicephalidean genus, Zanobatocestus gen. n., is proposed for two new species found parasitising the spiral intestine of the striped panray, Zanobatus schoenleinii (Müller et Henle), off Senegal that are highly unusual in acetabular morphology. Unlike the members of the 21 recognised lecanicephalidean genera, which possess simple, uniloculate suckers or bothridia, Zanobatocestus minor sp. n. and Z. major sp. n. possess biloculate bothridia. The form of their apical structures and cocoons readily distinguish the two new species from one another. Zanobatocestus minor sp. n. exhibits an apical modification of the scolex proper that is narrow and elongated, an apical organ that is small and internal, and eggs in cocoons forming linear strands, whereas Z. major sp. n. exhibits an apical modification of the scolex proper that is wide and short, an apical organ that is extensive and primarily external, and eggs in cocoons primarily as doublets with bipolar filaments. Given the typically high host specificity of lecanicephalidean cestodes, as parasites of the only genus and species currently considered valid in the family Zanobatidae, Zanobatocestus gen. n. is likely to remain one of the less specious lecanicephalidean genera.

An enigmatic new tapeworm, Litobothrium aenigmaticum, sp. nov. (Platyhelminthes : Cestoda : Litobothriidea), from the pelagic thresher shark with comments on development of known Litobothrium species

An enigmatic new tapeworm is described from pelagic thresher sharks in México and Taiwan. While lsrRNA (D1-D3) data robustly place it in the Litobothriidea, it bears essentially no morphological resemblance to other members of the order. Instead it superficially resembles the freshwater fish-inhabiting Caryophyllidea. Its scolex consists of a simple dome-shaped scolex proper and an extensive cephalic peduncle housing four distinct tissue types. It is hyperapolytic, thus reproductive anatomy is unknown. Developmental data show typical litobothriideans bear basic elements of their adult scolex upon entering the definitive host, undermining the notion that the new cestode represents a distinct litobothriidean life cycle stage. Scanning electron microscopy revealed the new species shares bands of distinctive microtriches with its congeners. In combination these data justify establishment of Litobothrium aenigmaticum, sp. nov.; the generic, familial and ordinal diagnoses are emended accordingly. Unlike typical litobothriideans, each worm is associated with a mucosal expansion at its attachment site, like those seen in some caryophyllideans. This pathological change may represent a worm-induced host response serving to reinforce attachment of the simple scolex to the mucosa. If so, the convergence of this litobothriidean on a morphology like that seen in the distantly related Caryophyllidea is a result of similarity in mode of attachment.

Synergy advances parasite taxonomy and systematics: an example from elasmobranch tapeworms

The synergism facilitated by a series of recent developments has conspired to catalyze rapid advancements in the taxonomy and systematics of elasmobranch tapeworms. These developments are: (1) increased interest in global biodiversity; (2) globalization-facilitated communication; (3) enhanced microscopic and digital technologies; (4) availability of web-based taxonomic resources; (5) ease of use and low cost of molecular techniques and (6) the impressive repertoire of available phylogenetic methods. As a consequence, an estimation of global elasmobranch tapeworm diversity is now within our grasp, as is a basic understanding of the effort and resources required to complete the discovery and description of this fauna globally. The generation of robust hypotheses of the phylogenetic relationships for most elasmobranch-parasitizing cestode orders is also well underway. An international community of cestodologists has emerged and through their sharing of knowledge and specimens is making great strides towards expanding knowledge of the cestode fauna of vertebrates worldwide. It is important that these efforts continue to move forward in a collaborative fashion, integrating morphological and molecular data, but also fully engaging elasmobranch taxonomists and systematists. It is equally important that efforts to characterize and describe global biodiversity are not derailed by such seductive, but ultimately unrewarding impracticable initiatives as molecular taxonomy. Integrated taxonomy is certainly not for the feint of heart, but those with the courage to pursue this strategy will be responsible for maintaining and enhancing the biologically relevant context required for effective species recognition well into the future.