Retroporomonorchis pansho n. g., n. sp., an unusual monorchiid trematode exploiting an atypical host

Abstract

The Monorchiidae Odhner, 1911 are well represented in tropical and subtropical marine fishes worldwide but rarely reported from the Lutjanidae, an important family of tropical fishes that prey mainly on demersal fishes, decapods and cephalopods. Here, we report the first monorchiid from a lutjanid in Australian waters, Retroporomonorchis pansho n. g., n. sp. in Lutjanus fulvus (Forster), off Lizard Island on the northern Great Barrier Reef. It is morphologically and phylogenetically distinct among known monorchiids, resolves within the Monorchiinae Odhner, 1911, and is characterised by a relatively large ventral sucker, a sinistral genital pore immediately posterior to the ventral sucker, unfilamented eggs, a single testis, and vitelline follicles restricted to the level of the gonads. We assessed all previous records of monorchiids from lutjanid fishes and found only one to be convincing, that of Infundiburictus overstreeti (Gupta & Gupta, 1990) Wee, Cutmore, Pérez-del-Olmo & Cribb, 2020 from Lutjanus monostigma (Cuvier) in the Bay of Bengal. Another, Monorcheides xishaensis Shen, 1985, from Lutjanus argentimaculatus (Forsskål) in the Paracel Islands, South China Sea, is here recognised as a cryptogonimid, and is synonymised with Siphoderina asiatica Gu & Shen, 1979. In the remaining reports, the identity of the host is either ambiguous or doubtful, or the identity of the worm is not supported with sufficient evidence.This article was registered in the Official Register of Zoological Nomenclature (ZooBank) as urn:lsid:zoobank.org:pub:1FE1714A-3A57-4E38-998E-7B1E4042A7B7. This article was published as an Online First article on the online publication date shown on this page. The article should be cited by using the doi number. This is the Version of Record.

Three new species of Helicometroides Yamaguti, 1934 from Japan and Australia, with new molecular evidence of a widespread species

“…Wee et al . (2020 a ) observed that most reports of monorchiid infections in lutjanid fishes are unconvincing; just two are well-supported with evidence. Wee et al .…”

“…Sciaenid fishes are significantly less parasitized by monorchiids; to our knowledge, 10 species of monorchiids from five genera have been reported from the family, with a single species of Helicometroides, H. leiperi, reported only from O. ruber (see Ahmad, 1982). Wee et al (2020a) observed that most reports of monorchiid infections in lutjanid fishes are unconvincing; just two are well-supported with evidence. Wee et al (2020a) suggested that the two lutjanids reported as hosts of H. pseudovitellosus (see Madhavi, 1974) and H. vitellosus (see Durio and Manter, 1968) were likely haemulids as neither host was identified to species, lutjanids are easily confusable with haemulids, and as species of Helicometroides are known overwhelmingly from haemulids.…”

“…Wee et al . (2020 a ) suggested that the two lutjanids reported as hosts of H. pseudovitellosus (see Madhavi, 1974) and H. vitellosus (see Durio and Manter, 1968) were likely haemulids as neither host was identified to species, lutjanids are easily confusable with haemulids, and as species of Helicometroides are known overwhelmingly from haemulids.…”

“…longicollis Yamaguti, 1934 is represented by genetic sequence data. Recent phylogenetic analyses have reported it as sister to all other monorchiid taxa (Wee et al ., 2020 a , 2020 b , 2020 c ), or to all except Cableia pudica Bray et al ., 1996 (Panyi et al ., 2020; Wee et al ., 2021 b ).…”

Monorchiids (Digenea, Trematoda) of fishes in the Yucatán Peninsula, Mexico, with the description of three new species based on morphological and molecular data

“…Monorchiids are morphologically characterised by complex terminal genitalia armed with recurved spines, vitelline follicles in restricted fields, and well-developed uterine coils [11]. The genetic library for species allocated to the family has increased significantly in the recent years; several new species have been described following an integrative taxonomy approach, most of them from Australian marine fish [18,[25][26][27][29][30][31]. In a recent study, Wee et al [28] performed one of the most comprehensive studies for species in the genus Lasiotocus Looss 1907, a taxonomically problematic group within the Monorchiidae.…”