Revision of the European species of the genus Trachelipus Budde-Lund, 1908 (Crustacea: Isopoda: Oniscidea)

The European species of Trachelipus Budde-Lund, 1908 are revised. The generic diagnosis is extended. The species T. aegaeus (Verhoeff, 1907), T. arcuatus (Budde-Lund, 1885), T. ater (Budde-Lund, 1896), T. camerani (Tua, 1900), T. dijfkilis (Radu, 1950), T. nodulosus (C. L. Koch, 1838), T. palustris (Strouhal, 1936), T. rathkii (Brandt, 1833), T. ratzeburgii (Brandt, 1833), T. razzautii (Arcangeli, 1913), T. rhinoceros (Budde-Lund, 1885), T. squamuliger (Verhoeff, 1907), T. trilobatus (Stein, 1859), (77 troglobius Tabacaru & Boghean, 1989) and 7T vespertilio (Budde-Lund, 1896) are recognized as valid. Except for T. troglobius , redesriptions, figures and distribution maps are given. A key to species is provided. Nineteen names are new synonyms of the above mentioned ones; nine names become nomina dubia.     

Wittmannia antarctica N. G., N. Sp. (Nosematidae), a New Hyperparasite in the Antarctic Dicyemid Mesozoan Kantharella antarctica

ABSTRACT. Collections of the dicyemid mesozoan Kantharella antarctica were made in the Weddell Sea during the Antarctic Expedition of the research vessel RV Polarstern in 1990 and 1991. A diplokaryotic microsporidian was found infecting all nematogens from all the samples taken in both years. The infected cells contained all developmental stages. Merogony initially was monokaryotic and spoorogony of diplokaryotic sporonts was by multiple fission. The stained ovoidal spores measured between 4.3-6 μm X 1.7-2.3 μm. The ultrastructural findings come from 11 specimens of Kantharella antarctica that were cut in serial sections. All developmental stages were noteworthy because of the myelinosomes situated adjacent to each diplokaryon. Similarly conspicuous were some organelles in the spore: a prominent, extraordinarily electron dense anterior portion of the polaroplast and the posterior vacuole. The isofilar polar filament with a diameter of about 115 nm showed 9-11 coils. The great number of empty spore cases together with an extruded polar filament are indicative of an autoinfection. Though these characteristics resemble in part those of the genus Nosema from the family Nosematidae, the species in Kantharella antarctica differs from the former by its unusual development, life cycle and unusual host. Thus, this new species has been placed in a new genus and the name Wittmannia antarctica proposed.     

Photosynthesis in frost-hardened and frost-stressed leaves of Hedera helix L.

Abstract The purpose of this study was to determine the respective extents to which winter reduction of photosynthetic capacity in ivy (Hedera helix L.) is caused by direct frost injury to the photosynthetic apparatus and by preceding protoplasmic changes connected with the acquisition of frost tolerance. Potted juvenile ivy plants were placed in the open under natural weather conditions whilst others were hardened under controlled conditions and subjected to the desired frost stress. Low non-freezing temperatures induced frost tolerance in ivy leaves down to about – 12°C (50% injury = TL₅₀) without impairing net photosynthetic rate as measured under standard conditions (20°C, light saturation, natural CO₂ level; = Standard-F_n. Only if the leaves froze (below ? 3°C to ?4°C) was a reversible inhibition of Standard-F_n observed. As long as the temperatures did not fall below approximately ?8°C the inhibition was small and Standard-F_n reached about 80–90% of the control. In this case the stomatal opening narrowed, giving a poorer supply of CO₂ to the mesophyll cells. Maximal frost tolerance (TL_5O?20°C to ?24°C) developed only with severe frosts below about ? 10°C. After such frosts, Standard-F_n was reduced to less than 20% of the control. The dependence of the rate of net photosynthesis on the internal CO₂ concentration showed a lower initial slope, thus indicating disturbances of chloroplast functions. However, neither in outdoor plants nor in those artificially frosted at – 20°C could there be found an appreciable inhibition of the electron transport capacity from H₂O to dichlorophenol indophenol or of ribulose bisphosphate carboxylase. If intact, severely frosted ivy plants were then held at higher temperatures (20/15°C), Standard-F_n recovered completely in approximately 10 d. Furthermore, following a frost period with temperatures down to ?12°C, mild weather caused a distinct improvement in Standard-F_n in outdoor plants, and there was no loss of maximum frost tolerance. Thus it can be concluded that the inhibition of Standard-F_n after severe frosts is not due to the development of maximal frost tolerance, but rather may be attributed to frost damage to the photosynthetic apparatus.     

Aggregata dobelli N. Sp. and Aggregata millerorum N. Sp. (Apicomplexa: Aggregatidae) from Two Species of Octopus (Mollusca: Octopodidae) from the Eastern North Pacific Ocean

ABSTRACT. Gamogony and sporogony of two new species of Aggregata (Apicomplexa: Aggregatidae) commonly were observed during histopathological examination of the digestive tracts of octopuses from the National Aquarium in Baltimore. North Pacific giant octopus, Octopus dofleini martini Pickford 1964, from British Columbia and Washington state were infected with Aggregata dobelli n. sp. Sporocysts were smooth-surfaced, dark-staining, subspherical to subovoid, typically 18–31 μ m long by 15–27 μ m wide, and contained 9–22 sporozoites, 18–23 μ m long. California two-spotted octopus, Octopus bimaculoides Pickford and McConnaughey 1949, from California were infected with Aggregata millerorum n. sp. Sporocysts were smooth-surfaced, dark-staining, and subspherical to subovoid, 12–20 μ m long by 11–17 μ m wide, and contained 8–10 sporozoites, 18–31 μ m long. Both species infected the noncuticularized spiral caecum and intestine; A. millerorum n. sp. also infected the cuticularized esophagus and crop. Both parasites were present in the submucosa, muscularis, and serosa. Our observations of Aggregata infections in cuticularized regions of the gut and in the muscularis and serosa appear to be novel. Associated pathologic features included hypertrophy of invaded cells, edema, inflammation, and ulceration.     

The effects of elevated temperature on the photosynthetic efficiency of zooxanthellae in hospite from four different species of reef coral: a novel approach

Bleaching of reef corals is a phenomenon linked to temperature stress which involves loss of the symbiotic algae of the coral, which are known as zooxanthellae, and/or loss of algal pigments. The photosynthetic efficiency of zooxanthellae within the corals Montastrea annularis, Agaricia lamarki, Agaricia agaricites and Siderastrea radians was examined by pulse-amplitude modulation fluorometry (PAM) during exposure to elevated temperatures (30–36°C). Zooxanthellae within M. annularis and A. lamarki were found to be more sensitive to elevated temperature, virtually complete disruption of photosynthesis being noted during exposure to temperatures of 32 and 34°C. The photosynthetic efficiency of zooxanthellae within S. radians and A. agaricites decreased to a lesser extent. Differences in the loss of algal cells on an aerial basis and in the cellular chlorophyll concentration were also found between these species. By combining the non-invasive PAM technique with whole-cell fluorescence of freshly isolated zooxanthellae, we have identified fundamental differences in the physiology of the symbionts within different species of coral. Zooxanthellae within M. annularis appear to be more susceptible to heat-induced damage at or near the reaction centre of Photosystem II, while zooxanthellae living in S. radians remain capable of dissipating excess excitation energy through non-photochemical pathways, thereby protecting the photosystem from damage during heat exposure.