A Redescription of Serrasentis sagittifer (Rhadinorhynchidae: Serrasentinae) from Rachycentron canadum (Rachycentridae) with Comments on its Biology and its Relationship to Other Species of Serrasentis

Abstract

Adult and cystacanth forms of the acanthocephalan Serrasentis sagittifer from Australian coastal waters are redescribed and verified as the same species using both molecular and morphological data. This study provides the baseline 18S rDNA, 28S rDNA, and cox1 sequence data to serve as genetic barcode for S. sagittifer. The validity of the currently recognized species of Serrasentis is discussed. The most recently described species are junior synonyms of either Serrasentis nadakali or S. sagittifer, and a number of species are species inquirenda. When using morphological characters to distinguish the species of Serrasentis, consideration needs to be given to the maturity of the specimens, since the trunk elongates and the number and distribution of the ventral combs changes as worms mature, although the proboscis armature itself does not change. A simple key to assist in the identification of species of Serrasentis is provided. Adult S. sagittifer appear to be highly host specific to the cobia, Rachycentron canadum, in northern Australian waters, whereas cystacanths have been reported from a wide range of fish species. The relationship between host length and number of cystacanths shows that most paratenic infections are acquired as young fish, most likely via a crustacean intermediate host.

New records of cucullanid nematodes from marine fishes off New Caledonia, with descriptions of five new species of Cucullanus (Nematoda, Cucullanidae)

“…It is known that the distribution area of a parasite often coincides with that of its definitive host. Similar cases when the same parasite was recorded from the same host species both in the Atlantic and Pacific regions have recently been reported by Barton et al [1] and Moravec and Barton [9] for the acanthocephalan Serrasentis sagittifer (Linton, 1889) and the nematode Digitiphilometroides marinus (Moravec et de Buron, 2009), respectively, both parasitizing the marine fish (cobia) Rachycentron canadum (Linnaeus). Also the nematode Piscicapillaria bursata Moravec et Barton, 2019, a parasite of hammerhead sharks (Sphyrna spp.)…”

Molecular characterisation of acanthocephalans from Australian marine teleosts: proposal of a new family, synonymy of another and transfer of taxa between orders

“…Despite the many species of acanthocephalan reported from marine and terrestrial vertebrates of Australia (Edmonds, 1989;Barton, 1994;Pichelin et al, 1999;Smales, 2003;Smales & Weaver, 2015) molecular data have been generated for only a single species from this vast region, Serrasentis sagittifer (Linton, 1889) Linton, 1932 (Barton et al, 2018). The primary objective of this study was to provide new molecular data for acanthocephalans of marine fishes collected across over more than a decade from off the coast of Queensland, Australia, and place these species in the greater acanthocephalan phylogeny.…”

Integrative taxonomy of Serrasentis gibsoni n. sp. (Acanthocephala: Isthmosacanthidae) from flatfishes in the Gulf of Mexico

“…Additionally, due to inadequate species descriptions based on only one larval stage and/or an insufficient sample size, Barton et al (2018) designated five as species inquirenda , or uncertain ( Serrasentis longiformis Bilqees, 1974; Serrasentis niger Khatoon & Bilqees, 2007; Serrasentis sidaroszakaio Tadros, Iskandar & Wassef, 1979; Serrasentis sauridae Surekha & Vijayalakshmi, 2006; Serrasentis sciaenus Bilqees, 1972), four of which Amin (2013) had considered valid. Barton et al (2018) also recognized one valid species that was not included in Amin’s (2013) list, namely Serrasentis indicus Singh, Agarwal & Lakshmi, 1998. Thus, at the time of Barton et al ’s (2018) publication, the genus contained five valid species.…”

“…Barton et al (2018) also recognized one valid species that was not included in Amin’s (2013) list, namely Serrasentis indicus Singh, Agarwal & Lakshmi, 1998. Thus, at the time of Barton et al ’s (2018) publication, the genus contained five valid species. An additional species was described by Gupta (2021), whereby the genus Serrasentis now contains the following six valid species (Barton et al 2018; WoRMS 2023): Serrasentis indica Singh, Agarwal & Lakshmi, 1998; Serrasentis lamelliger (Diesing, 1854) Meyer, 1932; Serrasentis manazo Bilqees & Khan, 2005; Serrasentis nadakali George & Nadakal, 1978; Serrasentis sagittifer (Linton, 1889) Van Cleave, 1932; and Serrasentis synagrisi Gupta, 2021.…”

“…Serrasentis sagittifer , the type species, is the only species reported from this genus in the Americas (Barton et al 2018; Amin and Heckmann 2021 and citations therein). Cobia, Rachycentron canadum (Linnaeus, 1766) (Rachycentridae) is considered the primary marine definitive host of S. sagittifer (Barton et al 2018; Amin and Heckmann 2021).…”