Two New Species ofSaccocoelioides(Digenea: Haploporidae) with Phylogenetic Analysis of the Family, Including Species ofSaccocoelioidesfrom North, Middle, and South America

Abstract

Two cryptic species of haploporid digeneans belonging in Saccocoelioides are described from Costa Rica: one from a poeciliid fish, Poecilia gillii, and the other from a characid fish, Astyanax aeneus. Traditional morphological features are examined and found to be largely inefficient for differentiating among the new species and 20 New World congeners. Comparison of ribosomal DNA sequences among the 2 new species, 2 North American, 4 Middle American, and 3 South American species of Saccocoelioides, including the type-species Saccocoelioides nanii from Argentina and Saccocoelioides sogandaresi from Texas, is effective in differentiating among these species. A Bayesian inference analysis is conducted using a concatenated alignment of the same 2 ribosomal gene regions from 35 species belonging in the Haploporoidea and rooted by the atractotrematid Isorchis anomalus. The analysis provides stronger support for a close relationship between species in Saccocoelioides and Intromugil; thus, Intromugil is transferred from the Waretrematinae to the Chalcinotrematinae. Additionally, interrelationships among 11 species of Saccocoelioides are resolved and reveal a distinct genetic rift suggesting the presence of 2 distinct lineages within the genus, 1 containing the type-species and the other containing a group of species that more closely resemble other genera in the subfamily. Taxonomy of Saccocoelioides is discussed, and observations made during the present study justify taking several taxonomic actions: new combinations are proposed for Saccocoelioides tilapiae n. comb., formerly in the now-defunct Culuwiya, and Saccocoelioides ruedasueltensis n. comb., formerly in Chalcinotrema; Saccocoelioides guaporense nomen novem is proposed for Lecithobotrioides elongatus; Saccocoelioides papernai is considered a junior subjective synonym of Saccocoelioides overstreeti; Saccocoelioides godoyi is considered a junior subjective synonym of Saccocoelioides szidati; Saccocoelioides magnorchis and Saccocoelioides saccodontis are considered species inquirendae; and Saccocoelioides adelae is considered a nomen nudum. Four new hosts are reported for Saccocoelioides cichlidorum: Amphilophus lyonsi, Amatitlania nigrofasciatus, Amatitlania septemfasciatus, and Hypsophrys nicaraguensis. Molecular data call into question some existing species identifications in Saccocoelioides and reveal that molecular tools combined with traditional taxonomy are required for accurately identifying species in the genus. Twenty-two species of Saccocoelioides are formally accepted, but it is noted that as new molecular data become available, some of these species may be transferred to other genera in the subfamily.

Testing the higher-level phylogenetic classification of Digenea (Platyhelminthes, Trematoda) based on nuclear rDNA sequences before entering the age of the ‘next-generation’ Tree of Life

“…(2016) with Macroderoidiidae McMullen, 1937 by Curran et al . (2018) and by Atopkin et al . (2019) with Haploporidae.…”

Host-induced phenotypic plasticity in Saccocoelioides lamothei Aguirre-Macedo and Violante-González, 2008 (Digenea: Haploporidae) a parasite of freshwater, brackish and marine fishes from Middle America

“…Curran et al . (2018) and Andrade-Gómez et al . (2019) evaluated the systematics of the genus Saccocoelioides by combining nuclear and mitochondrial molecular markers, and ecological and morphological characteristics, detecting an extraordinary diversity in the Americas.…”

“…Saccocoelioides Szidat, 1954 is the most diverse genus of trematodes belonging to the subfamily Chalcinotrematinae, and includes 24 recognized species, of which 14 are distributed in South America, seven in Middle America, two in North America and one in Puerto Rico; all these species are associated with freshwater, brackish and marine fishes from 10 families (Curran et al ., 2018; Andrade-Gómez et al ., 2019; Gallas and Utz, 2019). The genetic library of species of Saccocoelioides has increased significantly in the last few years.…”

“…(2019) evaluated the systematics of the genus Saccocoelioides by combining nuclear and mitochondrial molecular markers, and ecological and morphological characteristics, detecting an extraordinary diversity in the Americas. Currently, Middle America harbours seven species of Saccocoelioides , S. macrospinosus Andrade-Gómez et al ., 2019; S. orosiensis Curran et al ., 2018; S. tkachi Curran et al ., 2018; S. olmecae , Andrade-Gómez et al , 2016; S. cichlidorum (Aguirre-Macedo and Scholz, 2005) Andrade-Gómez et al ., 2017; S. chauhani Lamothe-Argumedo, 1974; and S. lamothei Aguirre-Macedo and Violante-González, 2008.…”

“…Saccocoelioides lamothei was described from the Pacific fat sleeper fish, Dormitator latrifons Richardson, 1844, from coastal lagoons of Guerrero state, Mexico (Aguirre-Macedo and Violante-González, 2008), and was subsequently reported as being associated with four fish species from three families (Poeciliidae, Profundulidae and Gobiidae) along the Pacific coasts of Middle America (Aguirre-Macedo and Violante-González, 2008; Pinacho-Pinacho et al ., 2015; Andrade-Gómez et al ., 2016, 2017, 2019; Curran et al ., 2018). Curran et al .…”