Studies on the Phylogenetic Implications of Ontogenetic Features in the Poecilostome Nauplii (Copepoda : Cyclopoida)

Larval Development of Caribeopsyllus Amphiodiae (Thaumatopsyllidae: Copepoda), an Enterozoic Parasite of the Brittle Star Amphiodia Urtica

“…Such an NI maxillule has not been recorded in Cyclopoida, Siphonostomatoida, and M. hamatapex (Izawa, 1987;Grygier and Ohtsuka, 1995), and in many copepods, the one-seta or one-spine maxillule does not appear until NII or NIII (Izawa, 1987). Although the precocious formation of the maxillule might suggest that the putative NI is actually an NII that was preceded by a very short-lived and overlooked NI, the presence of a primordial maxillule at NI is also observed in harpacticoids such as Longipedia, Microsetella, Sunaristes, and Canuella (Izawa,1987), and in mystacocarids (Olesen, 2001).…”

“…No other species of copepod is known to possess a similarly armed labrum in NI. Its NI antennule has the setation 1, 2, and 3, which distinguishes it from other copepods that have the general setation at NI of 1, 3, and 2 þ 1 aesthetasc (Izawa, 1987). It is notable, because of the relationship that has been posited (Ho et al, 2003) between thaumatopsyllids and monstrillids (a group recently placed within the Siphonostomatoida by Huys et al, 2007), that in advanced metanauplii of C. amphiodiae, the mandible becomes a massive structure, the exopod is transformed into a robust claw, and the inner distal portion of the first endopodal segment projects as a robust process forming a chelate complex with the distinctly curved, hook-like endopod.…”

“…These large metanauplii resemble the late naupliar stages of cyclopoids, harpacticoids, and calanoids, which have a bilobate maxillule as NIV larvae (Izawa, 1987), and setation of the maxillule is typical for NV stage copepods (Ferrari and Dahm, in press). A 0.47 mm-long metanauplius had ventral leg buds with projecting terminal setae (Figs.…”

The naupliar stages of Cyclopina yutimaete Lotufo (Cyclopinidae, Cyclopoida)

“…The spine-like maxillule, present in NII and NIII of C. yutimaete, was not observed in C. longifera. In the latter, the lobed maxillule appears in NIII, whereas in C. yutimaete it appears in NIV, as in most cyclopoid nauplii (Izawa, 1987). The caudal armature differs in the last naupliar stages of C. yutimaete and C. longifera.…”

“…The masticatory protuberance in C. longifera is laminated and in C. yutimaete it is pointed, and formed by two hook-like spines. C. longifera has a one-segmented endopod in the mandible, differing from all the other cyclopoid nauplii (see Izawa, 1987). The exopod of the mandible has 4 segments in NI-NVI in C. longifera.…”