Embryonic development of the southern surf crab Ovalipes trimaculatus (Decapoda: Brachyura: Portunoidea)

The embryogenesis of Ovalipes trimaculatus, a member of the highly valued portunid swimming crabs, was studied under nearly constant temperature (13±1°C), salinity (33) and photoperiod (14 h light:10 h dark) conditions. A five-stage scale of embryonic development was defined for the species. Time required to complete development averaged 35.7±2.11 days, showing no significant differences between embryos located in inner, middle and outer portions of the egg mass. The egg chorion was rounded and showed the highest growth in diameter between stages I (morula-blastula-gastrula) and II (primordium of larval structure) and between stages III (appendage formation) and IV (eye formation). Results reported here provide a baseline for optimizing hatchery operations and useful information for management purposes.

A holistic re-interpretation of the phylogeny of the Pycnogonida Latreille, 1810 (Arthropoda)*

The internal and external relationships within the Class Pycnogonida are rationalized based on the entire history of whole-animal understanding, detailed morphometrics, the fossil record, larval structure, mathematical multivariate analyses, and molecular analyses (electrophoretic protein and DNA). The pre-Jurassic fossils are placed in separate orders, with the Lower Silurian Haliestes giving the clearest indications of the form of a hypothetical “protopycnogonid”. Living forms, together with some Lower Devonian and the Jurassic fossils, are retained in the Order Pantopoda. No relationships to other Classes of the Arthropoda are yet indicated, and the concept of the Pycnogonida as a sister group to the Euarthropoda is maintained. The Pantopoda are divided into two suborders, isolating the Austrodecidae. The remaining taxa are classified into six superfamilies, on a consensus of overall morphological trends, larval forms, and the findings of the only previous comprehensive morphological multivariate analysis, and recent molecular analyses. The Colossendeidae, Pycnogonidae and Rhynchothoracidae are isolated within their own superfamilies. The Ammotheidae sensu lato is subdivided (within one superfamily), unfortunately leaving a number of genera incertae sedis. The Nymphonidae, Callipallenidae and Pallenopsidae are associated within another superfamily. The Jurassic fossils are placed within the Endeidae within a superfamily together with the Phoxichilidiidae, while some Lower Devonian fossils remain incertae sedis. Diagnoses are given as appropriate where possible.

The New World genus Lathrapanteles n. gen.: Phylogeny and placement in the Microgastrinae (Hymenoptera: Braconidae: Cotesiini)

The new genus Lathrapanteles is erected for Sathon papaipemae (Muesebeck) and three new species, L. ampyx (type locality, Cali, Colombia), L. fuscus (type locality, Notre Dame du Portage, Québec), and L. heleios (type locality, Mer Bleue, Ottawa, Ontario). The genus and species are described from cocoons, adult and larval structure, and distribution. Host-dependent variability in the first tergum of the metasoma of L. papaipemae n. comb. is discussed. A key to species and reconstructed phylogeny are given for Lathrapanteles. Placement of the genus in the Cotesiini and its effect on microgastrine classification is discussed.

The Reproduction of the Entozoic Nemertean Gononemertes australiensis Gibson (Nemertea: Hoplonemertea : Monostylifera) - Gonads, Gametes, Embryonic Development and Larval Development

G. australiensis is an entozoic nemertean found in the atrium of the ascidian Pyura pachydermatina (Herdman) var. intermedia Herdman. The host is common in the low intertidal and shallow sublittoral waters of the Sydney region of New South Wales. The nemertean is dioecious and possesses numerous gonads. In mature female worms, oocytes at different stages of maturity are always found throughout the body. The more mature oocytes lie close to the gut. Each temporary gonad produces several oocytes. The mature male worms contain ripe testes close packed within the parenchymal tissue along the body. The spermatozoon of G. australiensis has a head 6.5 µm long and a tail 38 µm in length. The head is rod- shaped with a blunt simple acrosome. The base of the head is surrounded by a mitochondria1 bulge which also encloses the connecting piece. A close apposition between the nucleus and the mitochondrion occurs in this area. The sperm is intermediate in type between primitive and modified nemertean spermatozoa. The egg of G. australiensis is spherical, yolky, 0.18mm in diameter and surrounded by a glutinous membrane. Fertilization is external. Cleavage, gastrulation and later embryonic development are similar to those of other hoplonemerteans and the resulting larva is of the hoplonemertean type. The larva is free- swimming for 3-5 days before invading a host. Some features of larval structure and behaviour are specializations associated with the entozoic habit of the nemertean. The development of the larval ocelli, lost soon after host invasion, is one of these. The young larva is photopositive, but after the ocelli have formed it becomes photonegative. Older larvae respond to a water current by an attachment response. No stomodaeum is formed during embryonic or larval development and completion of the differentiation of the proboscis is delayed until host invasion takes place. The larva exists on yolk until this time. The resources of the larva are concentrated on host location rather than on the feeding, growth and continued development typical of the larvae of other free-living hoplonemerteans.

Nesting behaviour and larval stages of some Australian nyssonine sand wasps (Hymenoptera : Sphecidae)

Study of the nesting behaviour and larval structure of several nyssonine sand wasps in eastern Australia reveals that these species closely resemble related species in the northern hemisphere. Austrogorytes bellicosus (Smith) makes multicellular nests in coarse sandy soil and provisions them with eurymelid bugs, laying the egg longitudinally on the topmost bug in the cell. Use of the hind legs in digging the nest, as well as certain features of larval structure, suggest that Austvogorytes is properly considered a very generalized nyssonine wasp. Clitemnestva plomleyi (Turner)(= Astaurus hylneoides Rayment, new synonymy), regarded as a structurally primitive sand wasp, preys upon leafhoppers (Cicadellidae) and is believed to utilize pre-existing vertical holes in hard soil. Sphecius pectoralis Smith, on the other hand, digs a long burrow in friable sand and makes up to 12 cells, provisioning them with cicadas. The larva of this species closely resembles that of other members of its genus. Members of the genus Bembecinus also prey on homopterous insects but exhibit two major behavioural specializations: the egg is laid in the empty cell on a pedestal of sand grains and provisioning is progressive. Four members of this genus were studied: egens (Handlirsch), antipodum (Handlirsch), hirtulus (Smith), and an unindentified species.