Temporal variation in egg-capsule deposition by Nassarius vibex (Gastropoda: Nassariidae)

The morphology and the deposition periods of egg capsules by the bruised nassa Nassarius vibex were investigated on two beaches located on the southeast coast of Brazil. The nassariids were associated with the charru mussel Mytella charruana, which forms beds on soft mud-bottoms. A total of 1558 capsules were collected, only from the fronds of the green alga Ulva lactuca, 859 for Camaroeiro Beach and 699 for Cidade Beach. The mean sizes of the egg capsules and numbers of eggs or larvae per capsule were similar on the two beaches, as were the periods of capsule deposition. At Camaroeiro Beach, capsules first appeared in May 2006, reached a peak in August 2006, and disappeared in December 2006. At Cidade Beach, the first capsules were recorded in July 2006, with a peak in August 2006. A second peak was also observed at this beach between January 2007 and April 2007. The two periods of deposition recorded at the latter beach may indicate two periods of recruitment in the same year for N. vibex. Regarding the influence of intertidal level on capsule deposition, there was a significant difference in the number of capsules between the levels at Camaroeiro Beach (F= 7.445, p<0.05), and for the second capsule-deposition peak at Cidade Beach (F= 6.382, p<0.05). This study revealed a selective pattern of capsule deposition, with individuals of N. vibex using only fronds of U. lactuca. This process was influenced by the morphodynamics of the two beaches, with the nassariids maximizing the survival of embryos by depositing more capsules and more eggs per capsule in better-protected parts of the mytilid beds.

The larval morphology and nest habits of Trypoxylon (Trypargilum) rogenhoferi Kohl 1884 (Insecta: Hymenoptera: Crabronidae)

The present study describes different preimaginal stages of Trypoxylon rogenhoferi examined by Scanning Electron Microscopy (SEM) and compares the results with observations on closely related species. Some notes on the nesting habits of this species, including their spider prey, nest parasites, and development time are provided. In short, T. rogenhoferi proved quite similar to the previous report on T. albitarse although SEM images are rarely presented in such descriptions. In fact the present study emphasized the importance of SEM images to describe fine morphological details that can be useful characters for taxonomic and phylogenetic studies. Images of some earlier development stages (first and second larval instar and egg) are presented for the first time, and compared with the few available data from other hymenopterans.

Egg surface structure of the freshwater toadfish Thalassophryne amazonica (Teleostei: Batrachoididae) with information on its distribution and natural habitat

The egg surface structure of Thalassophryne amazonica, a freshwater toadfish from the Amazon basin is described. Eggs of this species show a remarkable, highly unusual system of parallel ridges and intermittent grooves that originate at the equator of the egg and lead to the micropylar pit, at which they end in a spiralling pattern. A similar egg surface structure has so far been described only from a group of Asian anabantoid percomorphs, obviously not closely related to Thalassophryne. This egg surface pattern may enhance fertilization success by guiding sperm to the micropyle. We review museum records for T amazonica, present an updated map of its occurrence in the Amazon basin, and provide information on its habitat.

The preimaginal stages of the ensign wasp Evania appendigaster (Hymenoptera, Evaniidae), a cockroach egg predator

Evania appendigaster is a cosmopolitan wasp that deposits eggs in the oothecae of some species of cockroaches; its larvae then consume the cockroach eggs and embryos. It is a candidate for the biological control of cockroaches, but little is known about its basic biology. Here we describe the external morphology of all immature stages of E. appendigaster and compare them with the larvae of related species. The life cycle of E. appendigaster includes three larval instars, each with 13 body segments. Their mouthparts were generally reduced, except for the mandibles, which were always sclerotized and toothed, and were especially robust in second-instar larvae. Antennal and mouthpart sensilla were basiconic and difficult to observe. Larvae of E. appendigaster are similar in form to other described evaniid larvae, but quite different from the two available descriptions of larvae of gasteruptiid and aulacid wasps. Further descriptions of evaniid larvae will be useful in determining how widespread this morphology is within the family, and in understanding phylogenetic relationships within Hymenoptera.