Taxonomic Status of Ligophorus Mugilinus (Hargis, 1955) (Monogenea: Ancyrocephalidae), With a Description of a New Species of Ligophorus From Mugil Cephalus (Teleostei: Mugilidae) in the Mediterranean Basin

Abstract

Ligophorus mugilinus was originally described on the flathead mullet Mugil cephalus from the Gulf of Mexico. The species was later recorded in the Mediterranean Sea on the flathead mullet and in the Caribbean Sea on the white mullet Mugil curema. After examination of the type material and additional specimens of Ligophorus from the northwest Atlantic coast, the Caribbean Sea, and the Mediterranean and Black Sea, we observed morphological differences concerning haptoral and male copulatory structures between L. mugilinus from the northwest Atlantic and the forms from the Mediterranean and Black Seas. Accordingly, the latter specimens are described as a new species, Ligophorus mediterraneus n. sp. A redescription of L. mugilinus, including new morphometric data, is also given. The morphometric analysis of the Caribbean specimens suggested that their ascription to L. mugilinus is uncertain, but additional material is needed to clarify their specific identity. The results of this study, together with previous zoogeographical evidence, indicate that flathead mullets from different seas harbor different species complexes of Ligophorus. Given the coastal habits of the host, it is suggested that open oceans could act as geographical barriers favoring speciation within disjointed flathead mullet populations.

Ligophorus uruguayense sp. nov. (Monogenea, Ancyrocephalidae), a gill parasite from Mugil platanus (Mugiliformes, Mugilidae) in Uruguay

“…Specimens were recovered from both the right and left gill arches, with a higher number of parasites on the first and second gill arches Table II for abbreviations of metric variables) (Hargis, 1955), according to Sarabeev et al (2005), and L. huitrempe Fernández Bargiela, 1987; Gabriela Failla Siquier and Margarita Ostrowski de Núñez 98 (Table I). Prevalence of infection was 25.2% and mean intensity 13.7 (24.0) worms per fish.…”

“…Based on the features mentioned above, L. uruguayense differs from the following Mediterranean species described by (1) Euzet and Suriano (1977): L. szidati, L. chabaudi, L. macrocolpus, L. acuminatus, L. minimus, L. heteronchus, L. angustus, L. imitans, L. confusus;(2) Euzet and Sanfilippo (1983): L. parvicirrus; (3) Sarabeev et al (2005): L. mediterraneus; and (4) Rubtsova et al (2006): L. cephali, on the basis of the shapes of the ventral bar and anchors, the accessory piece of the penis and the vaginal aperture, the host species and the geographic distribution. Additionally, Ligophorus uruguayense differs from L. euzeti Dmitrieva et Gerasev, 1996, L. gussevi, L. llewellyni Dmitrieva, Gerasev et Pron'kina, 2007, and the three recently described species from the Japan Sea by Rubtsova et al (2007): L. domnichi, L. cheleus and L. pacificus, mainly in the shape of the accessory piece of the penis, the host species and the geographic distribution.…”

“…Ligophorus uruguayense is similar to L. mugilinus from the North Atlantic Ocean, as redescribed by Sarabeev et al (2005), by having the ventral bar larger than the dorsal bar, but can be distinguished from it by the shape of the sclerotized median process, the membranous anterior process, and the absence of a sclerotized thickening at its base. Ligophorus mugilinus has a claw-shaped penis accessory piece and a vaginal tube of uniform diameter, while L. uruguayense has a J-shaped penis accessory piece and a convoluted vaginal tube of variable diameter along its length.…”

“…mediterraneus Sarabeev, Balbuena et Euzet, 2005 cited for the Mediterranean Sea, from specimens formerly assigned to L. mugilinus by Euzet and Suriano (1977); and (3) L. vanbenedenii Parona et Perugia, 1890 cited for the Japan Sea, was first transferred to L. chabaudi by Euzet and Suriano (1977), and then described as a new species, L. domnichi Rubtsova, Balbuena et Sarabeev, 2007 (see Sarabeev andSarabeev et al 2005;Balbuena et al 2006;Rubtsova et al 2006Rubtsova et al , 2007.…”

“…The genus Ligophorus was established for species recovered from Mediterranean mugilids. In the Northern Hemisphere, new species of Ligophorus were found parasitizing mugilid species from the Black Sea, Azov Sea, Mediterranean Sea, North Atlantic Ocean, and Pacific Ocean (Dmitrieva and Gerasev 1996;Sarabeev and Balbuena 2004;Sarabeev et al 2005;Rubtsova et al 2006Rubtsova et al , 2007Dmitrieva et al 2007). In the Southern Hemisphere the only species so far described is L. huitrempe Fernández Bargiela, 1987 from a mugilid in the Chilean coast, Pacific Ocean.…”