Synchronism of naupliar development of Sacculina carcini Thompson, 1836 (Pancrustacea, Rhizocephala) revealed by precise monitoring

Abstract

Sacculina carcini is member of a highly-specialized group of parasitic cirripeds (Rhizocephala) that use crabs (Carcinus maenas) as hosts to carry out the reproductive phase of their life cycle. We describe the naupliar development of S. carcini Thompson, 1836 from a very precise monitoring of three different broods from three specimens. Nauplii were sampled every 4 h, from the release of the larvae until the cypris stage. Larval development, from naupliar instar 1 to the cypris stage, lasts 108 h at 18 °C. A rigorous sampling allowed us to describe an additional intermediate naupliar instar, not described previously. Naupliar instars are renumbered from 1 to 5. Nauplius 1 (N1) larvae hatch in the interna; N2 are released from the interna and last between 12 and 16 h; N3 appear between 12 and 16 h after release; N4 appear between 28 and 32 h; and N5 appear between 44 and 48 h. The cypris stage appears between 108 and 112 h. The redescribed morphologies allowed us to identify new characters. Antennular setation discriminates naupliar instars 3, 4 and 5. Telson and furca morphologies discriminate all naupliar instars. Furthermore, we demonstrate that the speed of larval development is similar within a single brood and between broods from different specimens, suggesting synchronization of larval development. From precise monitoring of broods every 4 h, we demonstrate that the life cycle of S. carcini includes five instars of naupliar larvae instead of four. The morphological characters of the larvae discriminate these naupliar instars and allow the identification of S. carcini from other Rhizocephala species. S. carcini larvae develop synchronously. Consequently, they might be an informative model to study larval development in crustaceans.

Larvae of Rhizocephalans with a Kentrogonid Type of Development and their Significance in the Taxonomy and Phylogeny of Parasitic Crustaceans

“…As a result, the genera Peltogasterella [4,57], Peltogaster [2], Sacculina [5], Polyascus [6], and Heterosaccus [54] were found to have five naupliar stages. Careful monitoring and observation of larvae every 4 h showed that the pelagic period of the wellstudied species Sacculina carcini also includes five naupliar stages [58], but not four stages, as suggested previously [10,61]. However, only four naupliar stages were found in Parasacculina sinensis [9] and Polyascus planus [59], despite that the larvae of the latter species were observed every 6 h.…”

“…It was suggested that this is the sixth rudimentary seta [57]. In Sacculina carcini, such a spine was not found in all examined specimens; therefore, the authors believe that it cannot be considered a true rudimentary seta [58]. In Lernaeodiscus rybakovi, S. carcini, and Heterosaccus papillosus, the fifth antennular seta is located on the middle segment at the early stages; later it is shifted to the distal segment [54,58].…”

“…4e). Their distal groove is indistinct [9,54,58,59]. The subterminal setae on the frontolateral horns are absent in sacculinid-type nauplii; however, the horns terminate in two processes (spines) (Fig.…”

“…5d). In sacculinid-type nauplii, the denticles are less pronounced; at the same time, there is a small tubercle between the furcal rami, which is not characteristic of the peltogastrid-type larvae [6,9,54,58,59].…”

Gonadal Degeneration and Hepatopancreas Alteration in Orange Mud Crab Scylla olivacea Infected With Sacculina beauforti (Crustacea; Rhizocephala; Sacculinidae)

“…All rhizocephalans infect other crustaceans (Høeg, 1995;Høeg and Lützen, 1995). Their unique life cycle begins with the hatching of sexually dimorphic nauplii, which upon several molts, metamorphose into male and female cyprids (Trédez et al, 2017). Female cyprids would develop into kentrogon larvae and infect hosts by penetrating hosts' integument, thereby transferring parasitic material (vermigon) into the hemolymph (Glenner and Høeg, 1994;Glenner, 2001).…”