Two new species of Elopicola (Digenea: Aporocotylidae) from Hawaiian ladyfish, Elops hawaiensis (Eastern Sea) and Atlantic tarpon, Megalops atlanticus (Gulf of Mexico) with a comment on monophyly of elopomorph blood flukes

Abstract

Elopicola bristowi sp. n. infects the blood vascular system of Hawaiian ladyfish, Elops hawaiensis, in the Eastern Sea. It differs from the only nominal congener Elopicola nolancribbi by the combination of having rows of ventrolateral tegumental spines, a proportionally long oesophagus, anterior caeca, vasa efferentia coalescing ventral to the posterodextral margin of the testis, a post-testicular metraterm, a dextral common genital pore lateral to the oötype, and genitalia that are enantiomorphic relative to those of E. nolancribbi. Elopicola franksi sp. n. infects the heart and blood vascular system of Atlantic tarpon, Megalops atlanticus, in the Gulf of Mexico. It differs from its congeners by the combination of lacking ventrolateral tegumental spines and having an elongate body (6× longer than wide), a proportionally long oesophagus, a compact testis at level of the distal ends of the posterior caeca, and a post-testicular common genital pore at level of the oötype. Phylogenetic analyses based on the small subunit ribosomal DNA (18S), large subunit ribosomal DNA (28S), and internal transcribed spacer 2 (ITS2) genes revealed considerable genetic differences between these taxa. The 18S+28S tree showed a monophyletic Elopicola sister to all aporocotylids infecting fishes of Euteleosteomorpha. The ITS2 tree showed Paracardicoloides yamagutii as the sister taxon to Elopicola spp.

Aporocotylids from batoid and elopomorph fishes from Moreton Bay, Queensland, Australia, including a new genus and species of blood fluke infecting the Giant shovelnose ray, Glaucostegus typus (Rhinopristiformes: Glaucostegidae)

“…The new specimens identified as E. bristowi closely match those in the original description of this species by Orélis-Ribeiro et al [40]. Generally, only minor morphological differences were observed between our specimens and those in the original description.…”

“…Generally, only minor morphological differences were observed between our specimens and those in the original description. The posterior oesophageal swelling noted by Orélis-Ribeiro et al [40] as present in all species of Elopicola (referred to as a "distal oesophageal chamber" by us here) was indistinct in our specimens, its presence only indicated by a slight proximal constriction and gastrodermal morphology and glandularisation different from the rest of the oesophagus. The gastrodermal morphology of the posterior oesophageal chamber was identical to that of the caeca.…”

“…Although a pharynx was described for all three species of Elopicola [40,42], no such structure was observed here. Pearson [43] recognised the digenean pharynx to be "a discrete muscular organ composed largely of radial fibres and set off from the adjacent musculature and parenchyma by a distinct and continuous capsule".…”

Neotropical Turtle Blood Flukes: Two New Genera and Species from the Amazon River Basin with a Key to Genera and Comments on a Marine-Derived Parasite Lineage in South America

“…Some fish blood flukes exhibit large inter-specific (intrageneric) 28S differences but are extremely morphologically similar, e.g., Elopicola spp. that are diagnosed by slight morphological differences but differ by as much as 22% in the 28S (Bullard, 2014;Ore´lis-Ribeiro et al, 2017). All of these comparisons do not detract from the seemingly strong (concordant with morphology) phylogenetic signal of the 28S in resolving inter-generic relationships among blood flukes, but they do suggest the need for the development of additional markers (in addition to 18S and ITS2) or genomic comparisons.…”

“…Using 2 EtOH-preserved and microscopically identified blood flukes per new taxon, total genomic DNA (gDNA) was extracted using the DNeasy TM Blood and Tissue Kit (Qiagen, Valencia, California) as per the manufacturer's protocol except that the proteinase-K incubation period was extended overnight and the final elution step used 100 ll of elution buffer to increase the final DNA concentration. Amplification and sequencing of the D1-D3 domains of the large subunit ribosomal DNA (28S) used the set of primers described in Ore´lis-Ribeiro et al (2017). PCR amplifications were performed using a total volume of 50 ll with 2 ll of DNA template, 0.4 lM of each primer along with 13 buffer, 2.5 mM MgCl 2 , 1 mM dNTP mixture, and 0.3 ll Taq polymerase (5 U/ll) (Promega, Madison, Wisconsin).…”