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A sacculinid rhizocephalan parasite,Sacculina lataBoschma, 1933, was discovered in the Beibu Gulf (= Gulf of Tonkin) west of Hainan Island, China, occurring in 7.4% of 363Charybdis miles(De Haan, 1835) collected by 30 trawls in July 2017. This is the first time thatS. latahas been recorded in Beibu Gulf and in the Chinese Exclusive Economic Zones (EEZs). Of the sampled crabs from 9 stations, 8 males and 19 females were found bearing externae ofS. lataon the abdomen, a prevalence of 4.1 and 11.2% in male and female crabs, respectively. The dominant size group of infected males was larger than that of females. There was no significant relationship between water depth and infection rate of the parasite. A positive correlation was found both between volume and weight of externae, and between surface area of externae and abdomen width of the host crabs. Carapace width and wet weight of infected crabs were significantly less than those of uninfected crabs. In male crabs, the first pleopods of infected individuals were shorter than normal, but their pleons were wider. The propodus of the chela of a parasitized crab was significantly larger than that of normal crabs, both in males and females. No rhizocephalan-infected female crab was found bearing eggs.

Specimens of the commercially important crab Portunus sanguinolentus (Herbst, 1783) were collected monthly in Honghai Bay, P. R. China and examined for the presence of two barnacles: the Lepadomorpha Octolasmis bullata (Aurivillius, 1894) and the Rhizocephala Diplothylacus sinensis (Keppen, 1877). O. bullata was observed in the branchial chambers and prevalence of their infestation varied in the monthly collections. High prevalence occurred in the time from June to August and from October to February. The mean intensity of O. bullata was 23.33 ± 18.91 barnacles per infested host, showing higher intensity in larger crabs. The parasite D. sinensis was observed on host surfaces with externae or scars, and their prevalence was high in winter and low in summer. Crabs parasitized by D. sinensis showed a heavier fouling by O. bullata than the non-parasitized crabs. Larger crabs were more vulnerable to the infestation of O. bullata and the parasitism of D. sinensis. Thus, interaction of O. bullata and D. sinensis may cause synergistic effects on the host’s health. Due to the great economic importance of the crab, attention should be paid to this relationship.

All available biological, ultrastructural, and molecular data support the conclusion that the cirripedian suborders, Rhizocephala and Thoracica, are closely related. Williamson’s speculations (Williamson, D. I., 2014. The origin of barnacles (Thecostraca, Cirripedia). Crustaceana,87: 755-765) that the so-called hybridogenesis can explain how Rhizocephala evolved, rest on a selective choice of other authors’ data and an ignorance of solid facts derived from decades of comparative anatomical and molecular studies.

I claim that hybridogenesis has played a vital part in the evolution of the Thoracica, Acrothoracica, Rhizocephala and Facetotecta. Hybridogenesis is the generation of new life forms and new life histories by sexual hybridization. It includes larval transfer, which explains the origins of all larvae, and component transfer, which explains the origins of cnidarians, lophophorates and thoracicans. I propose that adult thoracicans are descended from a hybrid between a crustacean and a non-arthropod, the genomes of which are expressed together. They are concurrent chimeras. Adult acrothoracicans are equivalent to the crustacean part of thoracicans. Nauplius larvae were added to the life histories of thoracicans and some acrothoracicans by later hybridizations. Adult rhizocephalans and juvenile facetotectans have no arthropod characteristics, and I claim that both these taxa acquired nauplius and cypris larvae by hybrid transfer. Extreme differences between the mitochondrial genomes of a sacculinid rhizocephalan and thoracicans are consistent with this view of rhizocephalan evolution. The Rhizocephala and Facetotecta are not members of the Cirripedia or the Arthropoda.

Parasitism is increasingly recognized as an important factor that can influence the structure and function of natural communities. The presence of externae of the parasite Sacculina carcini Thompson, 1836 was investigated in a population of the crab Carcinus maenas (Linnaeus, 1758) from the Mondego estuary, Portugal. A seasonal pattern of the S. carcini externae presence was observed with the highest values recorded in winter and the lowest in summer, ranging from 0.6 to 10%. The parasite seems to affect more females than males and the red morphotype presented higher prevalence than the green one. The size class [25, 35 mm[ was the one with the highest prevalence. The mouth of the estuary was the area where the most externally sacculinized crabs were caught. Apparently, the presence of the parasite tends to promote crabs migration to the mouth. This area coincides with the preferential spawning local of non-parasitized females. The infection by S. carcini influences the crab’s demography and its life history.

Batches of 100 female cypris of the rhizocephalan, Loxothylacus texanus Boschma, 1933 were selected and put into contact with megalopae of crabs of the genus Callinectes. Contacts lasted for 12 h and the organisms infected were then kept individually in plastic containers, and their growth was followed. At the same time, megalopae free of parasites were kept as controls. The infected organisms were monitored daily until the externae of L. texanus emerged. The time interval for emergence of the externae in male hosts was 79-110 days; and the growth rates were 0.19-0.29 mm day−1 with an average of 0.24 ± 0.037 mm day−. In females, the emergence interval of externae was 78-100 days; the growth rate was 0.18-0.23 with an average of 0.20±0.023 mm day−1. The mortality of the cypris is high (50-90%), which ensures that in the natural environment a high percentage of larval stages of Callinectes rathbunae Contreras, 1930 is recruited to the healthy population. Some crabs infected in the first stages die, which also ensures that the population of L. texanus is maintained relatively low in the natural environment. L. texanus infects the first stages of C. rathbunae, because this gives the parasite the time necessary to complete its life cycle. The emergence interval of the externa of L. texanus obtained in this study for C. rathbunae, is similar to that reported for the blue crab, Callinectes sapidus Rathbun, 1896, in other studies. Se formaron lotes de 100 cipris hembra del rizocefalo Loxothylacus texanus Boschma, 1933 y se pusieron en contacto con megalopas de especies del genero Callinectes, los contactos duraron 12 horas despues de lo cual los organismos infectados se colocaron de forma individual y se siguio su crecimiento. Al mismo tiempo, se mantuvieron megalopas libres de parasitos como control. Diariamente se revisaron los organismos infectados hasta la emergencia de las externas. El intervalo de tiempo de emergencia de las externas en los hospederos macho fue 79-110 dias; mientras que el intervalo de las tasas de crecimiento fue 0,19-0,29 mm dia−1 con promedio de 0,24 ± 0,037 mm dia−1; en el caso de las hembras el intervalo de emergencia de las externas fue 78-100 dias; el intervalo de las tasas de crecimiento fue 0,18-0,23 con promedio de 0,20 ± 0,023 mm dia−1. Se puede concluir que la mortalidad de las cipris es elevada (50-90%) lo cual asegura que en el medio natural un gran porcentaje de organismos de los estadios larvales de Callinectes rathbunae Contreras, 1930 se recluten a la poblacion sana, un porcentaje de los organismos infectados en los primeros estadios muere lo cual tambien asegura que la poblacion de L. texanus se mantenga relativamente baja en el medio natural, L. texanus infecta los primeros estadios de C. rathbunae porque esto le confiere el tiempo necesario para completar su ciclo de vida. El tiempo de emergencia de la externa de L. texanus obtenido en este estudio para en C. rathbunae es similar a lo reportado en otros estudios para el cangrejo azul Callinectes sapidus Rathbun, 1896.

Within parasitic barnacles of the family Sacculinidae, the genus Heterosaccus is the third largest, with 12 species infesting various brachyuran hosts throughout the world. As part of an effort to reconstruct rhizocephalan phylogeny we performed an analysis of four species of Heterosaccus and of selected sacculinid and non-sacculinid rhizocephalans. We used both molecular sequence data (16s rDNA and 18s rDNA) and morphological characters from an SEM analysis of the cypris larvae. Using Bayesian methods we obtained a highly supported tree in which the four species of Heterosaccus form a monophylum, whereas both the genus Sacculina and the family Sacculinidae are polyphyletic. The sistergroup to Heterosaccus is a clade consisting of the sacculinids Loxothylacus panopaei and the "classical" rhizocephalan Sacculina carcini. The molecular results found support in cypris morphology, where we identified two distinct synapomorphies for Heterosaccus, both present in male cyprids only: A large flap extending posteriorly from the third antennular segment, and the male-specific aesthetasc on the third segment being reduced to a rudiment or lacking completely. Female cyprids didn't show generic level apomorphies but resembled those of other sacculinid species. No morphological synapomorphies were identified between Heterosaccus, L. panopaei and S. carcini. While larval characters proved to be informative, we conclude that future studies on rhizocephalan taxonomy must rely primarily on molecular data, both to provide an overall phylogenetic framework and to assure an accurate identification of species for biogeographical and other biological purposes.

Hermit crabs of the species Pagurus criniticornis (Dana, 1852) parasitized by the poorly known colonial rhizocephalan Peltogasterella socialis (Müller, 1863), were collected in the infralittoral rocky/sandy area of Anchieta Island (São Paulo), Brazil. We report the presence and pattern of occurrence of this rhizocephalan in the P. criniticornis population. The hermit crabs were obtained monthly during 1999 by two people using SCUBA methods. A total of 992 hermit crabs were captured and examined for rhizocephalans. The studied population showed non-normal size distribution and only 2.11% of the sample specimens carried externae of P. socialis. The parasite occurrence was seasonal and varied with host size. Some signs of feminization were observed on P. criniticornis pleopods (elongation of the endopod and reduction of the exopod of pleopods for males and reduction in the size of endopods for females). This is the first report on this parasite/host relationship for this South American host species. This is the first record of P. socialis (Müller, 1863) subsequent to the species' description, and possible occurrence of the parasite on hermit crabs in the Bahamas is also reported.

According to the review by Du (1987) a male of the mitten crab, Eriocheir jap?nica (De Haan, 1835), infected by Polyascus gregaria (Okada & Miyashita, 1935) (Cirripedia, Rhizocephala) (cf. Glenner et al., 2003) can have five types of an abnormal abdomen with abnormal pleopods. We describe herein a type of parasitism-related intersexuality that has previously not been reported for Eriocheir jap?nica sinensis (H. Milne Edwards, 1853) (cf. Tang et al., 2002, 2003b). A possible mechanism for the origin of the sexual aberrations found in this specimen is also presented. The individual of Eriocheir jap?nica sinensis studied, shows degenerated male features as well as some slightly feminine characteristics, most probably as a result of a parasitic infection by Polyascus gregaria. Though parasitic castration has been reported extensively for many species of crabs (Reinhard, 1950, 1956; H0eg, 1984; O'Brien & Wyk, 1984; Sloan, 1984; Walker, 1985; Weng, 1987; O'Brien & Skinner, 1990; Walker et al., 1992; Alvarez et al., 1995; Grosholz & Ruiz, 1995; Glenner & Werner, 1998; Thresher et al., 2000; Torchin & Mitchell, 2004), we nevertheless consider it important to document the present find in some detail. This is because, in our opinion the features of this specimen allow, to some extent, to trace the possible mechanisms that cause the condition of sexual degeneration under the influence of the parasite.

Ovisac secretion by the paired colleteric glands of Sacculina carcini and Heterosaccus dollfusi (Rhizocephala, Sacculinida) was documented and studied at the ultrastructural level. Preparatory to oviposition, the epithelium of each colleteric gland secretes one branched, elastic, transparent ovisac. The ovisac wall consists of a reticulated inner zone, secreted first, and a dense outer zone. After secretion, the ovisac detaches from most of the secretory epithelium but remains anchored proximally in the gland until oviposition ends. The exterior ovisac surface is predominantly smooth and impervious. Proximally, however, the surface is irregular and perforated. During oviposition the eggs enter the paired ovisacs, forcing the ovisacs through the ovipores into the maternal mantle cavity. Simultaneously the ovisac volume increases approximately 100 times. The resulting paired egg masses, branched like the ovisacs, are brooded and ventilated in the mantle cavity. Ovisacs prevent that developing embryos are lost prematurely with the ventilation current. Within two days the egg masses solidify and attach to retinacula in the mantle cavity cuticle. The ovisacs, now probably obsolete, are no longer discernible. The literature on colleteric gland morphology implies that ovisacs are secreted by all Sacculinidae and perhaps other Rhizocephala with colleteric glands. Similarities in both the secretory process and morphology suggest homology between the colleteric glands of Sacculinidae and the oviducal glands of Thoracica (Cirripedia) and between their products.

A. J. (Sandy) Bruce was fascinated by animal life from his schooldays in southern England (and probably earlier), with interests in birds and freshwater crustaceans which, after completing his medical degree (‘Dr’ Bruce) and then compulsory National Service in Glasgow, led Sandy to join EAMFRO (East African Marine Fisheries Research Organisation) in Zanzibar in 1959. This was his first exposure to the tropics and the rich world of coral reefs and, most importantly of course, their as yet hardly studied shrimp fauna. This was the start of an enduring fascination with Pontoniinae and other shrimp taxa, which so far (production is not declining) has resulted in the description of one new family, 63+ new genera and 250+ new species, totalling approximately 7% of global shrimp diversity. Other crustacean groups also received attention, especially in the early years, with regular contributions appearing on the taxonomy of Brachyura, Stomatopoda, Isopoda, Rhizocephala, Mysidacea, and all major lobster groups. In a scientific career spanning over five decades, Sandy has produced in excess of 300 papers, routinely publishing 6-8 titles per year, and in some years as many as 12-14. Remarkably, until 1975 when Sandy took up the directorship at Heron Island Research Station, his taxonomic research was done almost entirely at home in his ‘spare time’.

[Une femelle adulte de Peltogasterella gracilis (Boschma) produit exclusivement soit de grands œufs, soit de petits œufs. Les grands œufs se developpent en grandes larves dont les fonctions sont celles des mâles larvaires. Les petits œufs donnent naissance a de petites larves qui se developpent en femelles adultes. Le cycle biologique est represente sous forme de diagramme dans la figure 1., Une femelle adulte de Peltogasterella gracilis (Boschma) produit exclusivement soit de grands œufs, soit de petits œufs. Les grands œufs se developpent en grandes larves dont les fonctions sont celles des mâles larvaires. Les petits œufs donnent naissance a de petites larves qui se developpent en femelles adultes. Le cycle biologique est represente sous forme de diagramme dans la figure 1.]