Gonad-infecting philometrid Philometra philippinensis sp. nov. (Nematoda, Philometridae) from the bigeye barracuda Sphyraena forsteri Cuvier (Sphyraenidae) off Mariveles, Bataan Province, Philippine archipelago

Abstract

We conducted a parasitological study to identify nematodes infecting the gonads of bigeye barracuda Sphyraena forsteri Cuvier (Sphyraenidae) caught in the West Philippine Sea, off the Mariveles coast, Bataan Province, the Philippine archipelago. Males and very tiny nongravid female philometrid nematodes were collected from the ovaries of the fish. Based on light and scanning electron microscope observations, and supported by molecular analyses of the partial nucleotide sequences of the 18S small subunit ribosomal DNA, the philometrid nematode was determined to be a new species belonging to the genus Philometra Costa, 1845 in the family Philometridae (Nematoda: Dracunculoidea), and was named P. philippinensis sp. nov. This new species was clearly distinguishable morphologically from other congeners that parasitize the gonads of marine fishes. Males have unique sickle-shaped spicules and gubernaculum, and a vulva-like cloacal opening. Following Dentirumai philippinensis Quiazon et Philometra robusta Moravec, Möller et Heeger, 1992, this is the third philometrid species and the first gonad-infecting philometrid from the Philippine archipelago.

First description of male Philometra thaiensis Moravec, Fiala et Dyková, 2004 (Nematoda: Philometridae) from the body cavity of the eyespot pufferfish Tetraodon biocellatus Tirant, and evolutionary relationships of this species with other dracunculoids as inferred from SSU rRNA gene sequences

“…Two species of two different genera, which were later described as Philometra overstreeti Moravec et de Buron, 2006 and Philometroides paralichthydis Moravec et de Buron, 2006, were confused under the name Margolisianum bulbosum (Blaylock and Overstreet, 1999;Moravec & de Buron, 2006). The inclusion of Margolisianum (genus inquirendum) within the Philometra and Philometroides clade, as also reported by Quiazon et al (2013), indicates that the genus Margolisianum is identical either with the genus Philometra or Philometroides. In addition, Clavinema fujimotoi (syn.…”

“…With the remarkable size difference between the tiny males (up to 12 mm for Philometra katsuwoni Petter et Baudin-Laurencin, 1986) (Moravec, 2006) and large gravid females (up to 530 mm for Philometroides seriolae [Ishii, 1931] (Quiazon et al, 2010)), most of the identified species are known only from female specimens. Currently, there are 29 philometrid species in Asia (including Piscinema barakense Gambhir et Ng, 2014 [species inquirendum]) that infect freshwater fishes (from 6 genera: Clavinema Yamaguti, 1935; Dentiphilometra González-Solís, Moravec et Tuz Paredes, 2007;Dentirumai Quiazon et Moravec, 2012;Philometra Costa, 1845;Philometroides Yamaguti, 1935;Piscinema Gambhir et Ng, 2014 [genus inquirendum]) and 45 species that infect marine and brackish-water fishes (from 7 genera: Buckleyella Rasheed, 1963; Clavinema; Clavinemoides Moravec, Khosheghbal et Pazooki, 2013;Paraphilometroides Moravec et Shaharom-Harrison, 1989;Philometra;Philometroides;and Spirophilometra Parukhin, 1971) (Gambhir & Ng, 2014;Moravec, 2014;Moravec & de Buron, 2013;Moravec & Ali, 2014;Quiazon & Yoshinaga, 2013). Philometrid nematodes affecting fish reproduction belong to the genus Philometra.…”

Two gonad-infecting species ofPhilometra(Nematoda: Philometridae) from groupers (Serranidae) off Tunisia, with a key toPhilometraspecies infecting serranid gonads

“…However, scanning electron microscopical (SEM) examinations of minute philometrid males made the identification more reliable and indicated considerable species diversity in these nematodes. To date, many gonad-infecting species of Philometra Costa, 1845 have been described from a variety of marine fishes belonging to different families and their number is quickly increasing [ 13 , 14 , 16 , 17 , 19 , 20 , 22 , 23 , 27 – 29 ].…”

Philometra dissimilis n. sp. from the ovary of Johnius belangerii (Sciaenidae) and other new records of philometrids (Nematoda: Philometridae) from fishes of the Bay of Bengal, India

“…At present, 67 gonad-infecting species of Philometra are known to parasitize marine fi shes (Moravec & de Buron, 2013;Quiazon & Yoshinaga, 2013;Moravec & Diggles, 2014aMoravec & Justine, 2014Moravec & Manoharan, 2014a, b;Moravec & Barton, 2015). However, as indicated by some recent studies of these nematodes from marine fi shes, they exhibit a high degree of host specifi city, when different morphologically well-distinguishable species of Philometra are recorded from different species of congeneric hosts in the same locality (Moravec & Manoharan, 2014a, b;Moravec et al, , 2016b.…”