New Genus of Blood Fluke (Digenea: Schistosomatoidea) from Malaysian Freshwater Turtles (Geoemydidae) and its Phylogenetic Position Within Schistosomatoidea

Abstract

: Baracktrema obamai n. gen., n. sp. infects the lung of geoemydid turtles (black marsh turtle, Siebenrockiella crassicollis [type host] and southeast Asian box turtle, Cuora amboinensis ) in the Malaysian states of Perak, Perlis, and Selangor. Baracktrema and Unicaecum Stunkard, 1925 are the only accepted turtle blood fluke genera having the combination of a single cecum, single testis, oviducal seminal receptacle, and uterine pouch. Baracktrema differs from Unicaecum by having a thread-like body approximately 30-50× longer than wide and post-cecal terminal genitalia. Unicaecum has a body approximately 8-12× longer than wide and terminal genitalia that are anterior to the distal end of the cecum. The new genus further differs from all other accepted turtle blood fluke genera by having a cecum that is highly convoluted for its entire length, a spindle-shaped ovary between the cirrus sac and testis, a uterine pouch that loops around the primary vitelline collecting duct, a Laurer's canal, and a dorsal common genital pore. Phylogenetic analysis of the D1-D3 domains of the nuclear large subunit ribosomal DNA (28S) revealed, with high nodal support and as predicted by morphology, that Baracktrema and Unicaecum share a recent common ancestor and form a clade sister to the freshwater turtle blood flukes of Spirorchis, paraphyletic Spirhapalum, and Vasotrema and that, collectively, these flukes were sister to all other tetrapod blood flukes (Hapalorhynchus + Griphobilharzia plus the marine turtle blood flukes and schistosomes). Pending a forthcoming emended morphological diagnosis of the family, the clade including Spirorchis spp., paraphyletic Spirhapalum, Vasotrema, Baracktrema, and Unicaecum is a likely placeholder for "Spirorchiidae Stunkard, 1921 " (type genus Spirorchis MacCallum, 1918 ; type species Spirorchis innominatus Ward, 1921 ). The present study comprises the 17th blood fluke known to infect geoemydid turtles and the first proposal of a new genus of turtle blood fluke in 21 yr.

A new species of Spirorchis MacCallum, 1918 (Digenea: Schistosomatoidea) and Spirorchis cf. scripta from chicken turtle, Deirochelys reticularia (Emydidae), with an emendation and molecular phylogeny of Spirorchis

“…Noteworthy regarding TBF-turtle cophylogeny, or rather the apparent lack thereof, although Spirorchis haematobius, S. collinsi and Vasotrema spp. reportedly exhibit a high degree of host specificity, the TBF clade (Roberts et al 2016a) and the Spirorchis clade (Fig. 9) are not concordant with recent turtle phylogenies (Guillon et al 2014, Spinks et al 2016).…”

“…Turtle scientific names and taxonomic authorities follow van Dijk et al (2014). Classification and anatomical terms for TBFs follow Roberts et al (2016a).…”

“…Turtle scientific names and taxonomic authorities follow van Dijk et al (2014). Classification and anatomical terms for TBFs follow Roberts et al (2016a).Specimens intended for molecular biology comprised the anterior end of one specimen of Spirorchis cf. scripta and the posterior end of one specimen of the new species.…”

Blood flukes of Asiatic softshell turtles: revision of Coeuritrema Mehra, 1933 (Digenea: Schistosomatoidea) and a new species infecting Chinese softshell turtles, Pelodiscus sinensis (Trionychidae), from Vietnam

“…Turtle scientific names and taxonomic authorities follow van Dijk et al (2014). Classification and anatomical terms for TBFs follow Luhman (1935 -genital sucker), Byrd (1939 -uterine pouch [see also Roberts et al 2016]), Yamaguti (1971 -Manter's organ), and Platt (1993 -median oesophageal pouch;1998 spines, plicate organ and most other terms).…”

“…The turtle blood flukes (TBFs; paraphyletic 'Spirorchiidae') comprise 84 accepted species (54 freshwater; 30 marine) assigned to 20 genera and that infect 37 freshwater and three marine turtle species (Platt 1993, Smith 1997a,b, Tkach et al 2009, Platt and Sharma 2012, Oré-lis-Ribeiro et al 2014, Roberts et al 2016. Seventeen TBFs of five genera (Hapalorhynchus Stunkard, 1922;Vasotrema Stunkard, 1926;Coeuritrema Mehra, 1933;Enterohaematotrema Mehra, 1940, Cardiotrema Dwivedi, 1967 infect softshell turtles (Testudines: Trionychidae) (Table 1), but only nine of 31 (29%) trionychids host a TBF, suggesting that perhaps numerous innominate TBFs infect this turtle lineage.…”