The infraorder Thalassinidea is a group of cryptic marine burrowing decapods of which the higher taxonomy is often contentious. The present analysis attempts to reconstruct phylogenetic relationship among 12 of the 13 currently recognized families using partial nuclear 18S, 28S rDNA and mitochondrial 16S rDNA sequences. The infraorder is divided into two distinct clades, with the first clade consisting of Thalassinidae, Laomediidae, Axianassidae and Upogebiidae, and the second clade including Axiidae, Calocarididae, Eiconaxiidae, Callianassidae, Ctenochelidae, Micheleidae, Strahlaxiidae and Callianideidae. Within the first clade, the Upogebiidae is the basal family. The Axianassidae shows low affinity to other laomediid genera indicating that it is a valid family. The interfamilial relationships are less well resolved in the second clade. The Axiidae is paraphyletic with respect to Calocarididae and Eiconaxiidae. Thus, the status of these two latter families is not supported if the currently defined Axiidae is maintained. All three families appear to be basal in the thalassinidean clade. The Micheleidae is closely related to the Callianideidae and they form a sister group to the Strahlaxiidae. The monophyletic Callianassidae aligns with the Micheleidae + Callianideidae + Strahlaxiidae clade. The relationship among the Axiidae + Calocarididae + Eiconaxiidae clade, Callianassidae + Micheleidae + Callianideidae + Strahlaxiidae clade and the Ctenochelidae cannot be resolved which might be due to a rapid radiation of the three lineages. Our results do not support the generally used classification scheme of Thalassinidea and suggest that the infraorder might be divided into two superfamilies instead of three as suggested based on larval morphology, second pereiopod morphology in adults and gastric mill structure. The two superfamilies are Thalassinoidea (i.e. Thalassinidae, Laomediidae, Upogebiidae and Axianassidae) and Callianassoidea (i.e. Axioidea + Callianassoidea, as defined in Martin and Davis (2001) but excluding Laomediidae and Upogebiidae). It also appears that gillcleaning adaptations are important in thalassinidean evolution while the presence of linea thalassinica is a result of parallel evolution.

In eusocial nests, colony task are divided among queens and workers, but how this division of labor develops is unknown for most species. We compared division of labor and aggressive behavior among queens and workers in the facultatively eusocial bee, Megalopta genalis, using nests with established queen-worker pairs and nests in which the incipient worker had recently emerged. We find that the majority of aggression is directed from queens toward workers in both incipient and established relationships. Established workers forage and perform trophallaxis as donors more frequently than queens, but both queens and workers perform trophallaxis as donors when workers are young. Queens spend significantly more time nest guarding than incipient and established workers, perhaps because older workers spend more time foraging and incipient workers spend significantly more time in cells than do queens. Our results show that the development of worker behavior involves dynamic temporal changes in task performance among queens and workers during the 10 days after worker emergence. During this establishment period, queens engage in maternal care by feeding their daughters, but are also aggressive toward them. This may be a mechanism by which queens coerce their daughters into becoming non-reproductive workers.

Abstract. The kuruma shrimp Penaeus japonicus Bate, 1888 (Decapoda : Penaeidae) is economically important in the global shrimp market. It was regarded as the only species in the subgenus Marsupenaeus. However, our previous molecular analyses revealed two cryptic species (Forms I and II) in this species complex. In this study, we confirm the phylogenetic relatedness between the two cryptic species; revise their taxonomic status; and review their range distribution. The name Penaeus pulchricaudatus Stebbing, 1914 (with type-locality off the eastern coast of South Africa), previously considered as a junior synonym of P. japonicus, is fixed for Form II through a neotype selection. P. japonicus (Form I) is only confined to the East China Sea (including Japan, its type-locality) and the northern South China Sea. P. pulchricaudatus is widely distributed in the South China Sea, Australia, the Red Sea, the Mediterranean, and the western Indian Ocean. Phylogenetic analysis shows that P. japonicus is genetically homogeneous yet P. pulchricaudatus exhibits a strong phylogeographical structure. The Mediterranean stock of P. pulchricaudatus originated from the Red Sea population, supporting the Lessepsian migration hypothesis. The presence of two closely related cryptic species in the P. japonicus species complex provides important insights into fishery management and aquaculture development.

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