Gigantobilharzia melanoidis n.sp. (Trematoda: Schistosomatidae) from Melanoides tuberculata (Gastropoda: Thiaridae) in the United Arab Emirates

Abstract

Delicate filamentous schistosomatids detected in the intestinal veins of experimentally infected chickens are here described as a new parasite species, Gigantobilharzia melanoidis, and details of its life cycle are given. It is the first complete description of a schistosome species that uses Melanoides tuberculata as an intermediate host. Apharyngeate ocellate brevifurcate cercariae found in 65 out of 950 M. tuberculata collected in a pond in Al Aweer, United Arab Emirates were used as infection material. The new species can be distinguished from the other species of the genus by the following combination of characters: caecal reunion in males situated anterior to seminal vesicle, a very short gynecophoric canal (gynecophoric canal length/body length ratio lower than 0.05) supported by 12-14 thickened bands. Cercariae of G. melanoidis can be distinguished from other Gigantobilharzia cercariae described in the literature based on the combination of these characters: flame cell formula 2[3 + 3 + (1)] = 14 and relatively longer tail stem in relation to body (tail stem length/body length ratio = 2). Under laboratory conditions at a temperature between 24 and 26 °C, M. tuberculata started to shed cercariae 7 weeks after exposure to miracidia. The prepatent period of G. melanoidis in experimentally infected chicken lasted between 43 and 49 days. The parasite inhabits the blood vessels mainly of the small intestine. Sections of adult worms and eggs were also found in histocuts of parenchymatous organs. Results of phylogenetic analysis corroborated that G. melanoidis is a distinct species; however, they also confirmed that the genus Gigantobilharzia is in need of revision and in future might be split into several genera.

Avian Schistosomes and Outbreaks of Cercarial Dermatitis

“…At the base of clade D is an unresolved group of avian schistosomes, most of which have been implicated in dermatitis outbreaks and comprise the most diverse range of both bird and snail (9 families) host use (13,40,(56)(57)(58)(59)(60)(61)(62)(63)(64)(65)(66). Current results based on all of the available sequence data in GenBank for the internal transcribed spacer (ITS) region indicate that there are about nine distinct lineages, only two of which are described: Gigantobilharzia and Dendritobilharzia (40,(64)(65)(66)(67)(68)(69).…”

“…Current results based on all of the available sequence data in GenBank for the internal transcribed spacer (ITS) region indicate that there are about nine distinct lineages, only two of which are described: Gigantobilharzia and Dendritobilharzia (40,(64)(65)(66)(67)(68)(69). Most of the lineages in this part of clade D have one to a few species and have been seen in only a few cases, many related to dermatitis outbreaks (12) ( Table 1).…”

“…For example, in the San Francisco Bay area (California), one beach in particular has annual cases of dermatitis (64). The prevalence of dermatitis caused by schistosomes from Valvata or Melanoides snails (63,65,66) depends on how often people use areas where these snails release cercariae.…”

A review on the molecular characterization of digenean parasites using molecular markers with special reference to ITS region

“…from geese from Europe and North America using morphological and molecular characterization through 28S, ITS and mitochondrial COI gene sequences. Schuster et al (2014) discovered new species, Gigantobilharzia melanoides from chickens and described its complete life cycle along with establishment of phylogenetic relationship using partial 18S, 28S and complete ITS-1, 5.8S and ITS-2 rDNA region. Through phylogenetic results G. melanoides is proved as distinct and new species.…”

Evaluation of the feeding preference between the aquatic macrophytes Egeria densa and Chara indica by the invasive mollusk Melanoides tuberculata

“…Therefore, it is able to maintain high population densities for long periods through high reproduction rates, rapid growth, and low mortality rates (Samadi et al, 1999;Andrade et al, 2012). Environmental ecological problems have been reported after its introduction to non-native environments (Schuster et al, 2014;Fernandez et al, 2014).…”