Two New Species of Encotyllabe (Monogenea: Capsalidae) from Brazil: Morphological and Molecular Evidence

Abstract

Currently, 24 species of Encotyllabe Diesing, 1850 (Monogenea: Capsalidae), are recorded as parasites on teleost fishes, but the validity of many species has been questioned due to deficient or incomplete descriptions. Almost all species in the genus have been described from one host species or closely related host species, suggesting host specificity, but some species, specifically Encotyllabe spari Yamaguti, 1934, have been reported from at least 19 species belonging to nine families in two orders (Perciformes and Scorpaeniformes) from Japan, Arabian Gulf and Brazil. Concerning Brazilian records of Encotyllabe spari and Encotyllabe cf. spari, seven species belonging to four families and two orders have been reported as hosts for this species. The aim of this study was to describe two new species of Encotyllabe from Brazil, previously considered as E. spari. Morphological and morphometric (multivariate analysis of proportional measurements standardized by total length) and molecular analysis (LSU rRNA and cox1 gene) were performed in order to identify the collected monogeneans. The description of two new species, namely Encotyllabe bifurcatum n. sp. and Encotyllabe parvum n. sp., parasitizing Pagrus pagrus and Orthopristis ruber, respectively, is the result of the three approaches. The main morphological differences from the most related species include a combination of body size, shape of the male copulatory organ, size and position of the testes. Our results suggest host specificity for members of Encotyllabe and specimens previously recorded as E. spari, other than those from the original description, must be revisited.

Morphological and molecular characterization of Encotyllabe vallei Monticelli, 1907 (Monopisthocotylea, Monogenea) from the gilthead seabream Sparus aurata Linnaeus (Teleostei, Sparidae) from the southwestern Mediterranean and notes on host specificity of the genus Encotyllabe Diesing, 1850

“…They have a broad host spectrum (Table 1), infecting various teleost fish families (Sepúlveda et al 2014). Currently, there are 24 species attributed to this genus (WoRMS 2023), however, the validity of several of these species has been questioned due to the incomplete and brief original descriptions (Taborda et al 2023), the unavailability or poor conditions of some type specimens (Sepúlveda et al 2014) and the lack of detailed redescriptions. Additionally, seven of the total recognized species were initially described based on only one or two specimens, which hinders the ability to understand intraspecific variability (Sepúlveda et al 2014).…”

“…Note that E. latridis mentioned by Lebedev (1967) was omitted because it is currently included in Mediavagina Lawler and Hargis, 1968. Encotyllabe masu Ishii and Sawada, 1938; E. monticelli Perez Vigueras, 1940; E. pricei Koratha, 1955 and E. punctatai Gupta et Krishna, 1980 as species inquirendae because these species were poorly described, based on only one or two specimens. 1 was originally described in an unpublished thesis and never published according to the rules of the International Code for Zoological Nomenclature; it is not considered valid (see Taborda et al (2023)). 2 Yamaguti (1934) noted that both E. pagelli and E. pagrosomi are parasitic in the sparid Pagrus auratus and probably more closely related to E. spari , but because the original papers of these species were inaccessible to him, he noted that his species should be looked upon as a provisional one. …”

“… 1 was originally described in an unpublished thesis and never published according to the rules of the International Code for Zoological Nomenclature; it is not considered valid (see Taborda et al (2023)). 2 Yamaguti (1934) noted that both E. pagelli and E. pagrosomi are parasitic in the sparid Pagrus auratus and probably more closely related to E. spari , but because the original papers of these species were inaccessible to him, he noted that his species should be looked upon as a provisional one. …”

“…1 was originally described in an unpublished thesis and never published according to the rules of the International Code for Zoological Nomenclature; it is not considered valid (see Taborda et al (2023)). …”

“…Encotyllabe vallei had been rarely mentioned, and apart from Radujkovic and Euzet (1989), the previous accounts provided scant or no morphometric data and lacked illustrations. Consequently, the brief original description has made it difficult to discern differences from other species (Taborda et al 2023). As a result, assessing its similarities to and differences from other Encotyllabe species remains challenging due to the absence of morphometric data which led to its recent classification as species inquirendae (Taborda et al 2023).…”