A new genus and species of "libelluloid" dragonfly, Jujusia maizgorda gen. n., sp. n., of the clade Italoansida Bechly, 1996, from the late Paleocene, Maíz Gordo Formation, north-western Argentina, is described. Its phylogenetic relationships within the clade Cavilabiata Bechly, 1996 are discussed.
A new copepod species, Acanthochondria sagitta sp. n., is described based on specimens collected from the flounder Xystreurys rasile (Jordan) (Pleuronectiformes, Paralichthyidae), caught in the coastal waters off Necochea, Buenos Aires Province, Argentina. The new species differs from its congeners by the following combination of characters: presence of three pairs of cephalic outgrowths; the triangular shape of the trunk with diverging postero-lateral processes; leg 2 of an intermediate shape between Types C and D, which projects laterally from the trunk, and Type B-V antennule bearing two proximal processes (one ventral and one dorsal) on the swollen basal portion.
Lernanthropus cynoscicola sp.n. (Copepoda: Lernanthropidae), a parasite of sciaenid fish Cynoscion striatus Cuvier from the coast of Argentina, is described and illustrated. The new species resembles five other species of Lernanthropus in general body shape, but it can be distinguished from them by the relatively short and tapered dorsal plate of the 4th leg-bearing segment, the length of the 4th legs being approximately equal to the rest of the body, and other differences. L. trachuri Brian, 1903 is reported for the first time in Argentina on Trachurus lathami from the coast of the Buenos Aires province.
A new species of Acanthochondria Oakley, 1927 (Copepoda, Poecilostomatoida, Chondracanthidae), parasitic on Serranus auriga (Cuvier) from the Argentinean coastal zone, is described and illustrated. The new species differs from its congeners by the relative length of the neck and the protopod of leg 2. This is the second record of this genus for the South-eastern Atlantic and the first one from a serranid host.
The three larval instars of Gymnochthebius jensenhaarupi (Knisch, 1924) are described and illustrated, including a detailed analysis of their chaetotaxy and porotaxy. The specimens used in this study were collected with adults of G. jensenhaarupi and have been identified as such by association. Comparative notes on the morphology of these larvae with other species of the subfamily Ochthebiinae are given. A hypothesis of phylogenetic relationships between G. jensenhaarupi and other members of Ochthebiinae with thoroughly described larvae is presented. The monophyly of Ochthebiinae is supported by additional larval features. On the other hand Ochthebius, as currently composed, seems to by paraphyletic. Gymnochthebius Orchymont, 1943 is confirmed as the sister group of Aulacochthebius Kuwert, 1887.
The third instar larva of Anacaena cordobana Knisch, and the egg case of Anacaena lutescens (Stephens) are described and illustrated. The taxonomic status of the immature stages of Anacaenini is clarified by comparing their morphology with that described in the literature. Larval descriptions of Anacaena and Paracymus published by Richmond (1920) are interchanged, as are the identifications of all subsequent authors based on Richmond's work. All Anacaenini genera for which larvae are known are diagnosed. A comparative morphological study of Anacaena larvae shows many similarities between Crenitis and Anacaena larvae, suggesting a close relationship between these two genera.