Karl J. Wittmann

MODIFICATION OF ASSOCIATION AND SWARMING IN NORTH ADRIATIC MYSIDACEA IN RELATION TO HABITAT AND INTERACTING SPECIES

ABSTRACT The distribution of Mysidacea has been studied in Strunjan Bay and islands off Rovinj (Istria, Yugoslavia). Underwater observations were made by diving, TV, and time-lapse-camera. Different species show a preference for certain bathymetric zones and, within a zone, occupy different substrates and distinct microhabitats or differ in period of activity, so that they are usually aggregated in monospecific swarms. Occurrence of polyspecific swarms is referable to overlapping requirements and to interaction of species. Swarm formation is controlled by two patterns: habitational and inter-individual responses. The relative influence of both patterns differs in species - this is referable to different substrate-relations.

Reappraisal and range extension of non-indigenous Mysidae (Crustacea, Mysida) in continental and coastal waters of eastern France

A survey of species belonging to the family Mysidae, conducted in June 2007 in fresh- to brackish waters of eastern France, revealed a recent range extension of the invasive Ponto-Caspian species Hemimysis anomala to the Moselle, Saône, and Rhône rivers. In the estuary of the Grand Rhône it reached for the first time the Mediterranean coast. The network of navigation canals in NE France was likely a key element of its north to south pathway starting from the Rhine River. Important range extensions were also noted for Limnomysis benedeni in this network and in the Moselle River. The euryhaline species Neomysis integer, endemic in coastal waters of the NE Atlantic, was found in the Rhône delta, thus confirming previous very rare records in the 1930–1950s from the Mediterranean coast of France. Invasion mechanisms and pathways, expansion potential, and establishment conditions of the species are discussed.

Morphogeographic variations in the genusMesopodopsis Czerniavsky with descriptions of three new species (Crustacea, Mysidacea)

Most of the exceptional morphological features of the genusMesopodopsis are shared withNanomysis, Diamysis, andLimnomysis in a mosaic-like pattern. This group, comprising euryhaline species from fresh-to metahaline waters, has its centre of recent species richness in the Mediterranean to Ponto-Caspian region.Within the genus one may distinguish two morphogeographic groups, Euro-African species with a spine below the statocyst, and Indo-Australasian species without this spine. Detailed study from the entire distribution range indicates thatM. slabberi (van Beneden) should be split into 4 species: the nominal form from the NE-Atlantic, Mediterranean, and Black Sea, with 5–8 segments on the tarsus of the fourth thoracic endopod;M. aegyptia n.sp., widely distributed in the Mediterranean, with 7–9 segments on this tarsus as well as dimorphic setation patterns on the eighth tarsus;M. tropicalis n.sp. from equatorial W-Africa with 5–6 segments and dimorphic setation patterns on the mandibular palp; andM. wooldridgei n.sp. from South African waters with 9–12 segments on the tarsal joint of the fourth thoracic appendage, respectively.A key to the seven known species of the genus is given.

Structure of recent and fossil mysid statoliths (Crustacea, Mysidacea)

Statoliths of 61 Recent species representing all subfamilies of Mysidae were studied with special emphasis on internal structure. In addition 5 samples of fossil statoliths from Miocene deposits were examined. Species of Boreomysinae and Rhopalophthalminae show simple roughly spherical organic statoliths, with setae originating from the sensory cushion and anchored in the statolith with distal branches extending shortly below the surface. All other subfamilies possess mineralized statoliths of greater structural complexity, with differentiation in core and mantle, where each part may consist of up to three layers. Habitus is hemispherical to discoidal. External gross structures are dorsal tegmen, ventral fundus, and the ambitus forming the outer toroidal to semi‐toroidal circumference. Setae penetrate the mantle through mineralic canals and insert on the surface of the core. As suggested by congeneric species of Schistomysis, there is no principal structural difference between statoliths mineralized with fluorite compared to vaterite. However, vaterite statoliths tend to be more often of moruloid appearance and are exceptional by showing a central conical hole (the hilum) or a central cavity in certain forms. These structures are typical of fossil calcite statoliths. In vaterite and fluorite statoliths, the mantle shows radially arranged (= spherulitic) crystal aggregates. Such arrangements are badly preserved in fossil calcite statoliths. In large extant statoliths, concentric structures, mainly in the form of superficial striation and/or concentric microstrata, are visible in coexistence with radial aggregates. Stratification is possibly due to stratified deposition of the nonmineralized gland product, while the spherulitic structure is indicative of subsequent radial growth of crystal aggregates. The structure of accessory fluorite statoliths in the statocyst of Mesopodopsis slabberi leads to the hypothesis that mantle material is formed by secretions of the caudal statocyst gland. After demineralization of fluorite, vaterite and calcite statoliths, an organic template remains showing most essential morphological features of the statolith. From this we conclude that the structure of the statolith is (almost) entirely matrix mediated.

Two new species of Heteromysini (Mysida, Mysidae) from the island of Madeira (N.E. Atlantic), with notes on sea anemone and hermit crab commensalisms in the genus Heteromysis S. I. Smith, 1873

[Faunistic studies and a survey of anemone commensals in near-shore habitats at the Island of Madeira yielded two new species belonging to the genus Heteromysis: H. dardani commensal with the diogenid hermit crab, Dardanus calidus (Risso, 1827), and H. wirtzi with the sea anemone, Telmatactis cricoides (Duchassaing, 1850). Both species differ from previously known E. Atlantic species by a flagellate, modified seta on the inner distal corner of the antennular trunk. H. wirtzi shows more spines on the second to fourth male pleopods, and four spines on the endopods of the uropods compared to three spines in H. dardani. Morphological differences suggest that commensalism of Heteromysis species with hermit crabs has independently evolved in the (sub)tropical shelf areas of the Indo-Pacific, E. Pacific, and Atlantic oceans. The W. Atlantic anemone commensals belong to two morphologically distinct lines within the subgenus Olivemysis Băcescu, 1968, one of which shows close relationships to the two newly described E. Atlantic species. A key to the species of Heteromysis known from the E. Atlantic and the Mediterranean is given. Faunistische Untersuchungen und eine Erfassung von Anemonen-Kommensalismen entlang der Kusten von Madeira ergaben zwei neue Arten der Gattung Heteromysis: H. dardani, ein Kommensal der Einsiedler-Art Dardanus calidus (Risso, 1827) und H. wirtzi, ein Kommensal der Anemone Telmatactis cricoides (Duchassaing, 1850). Beide unterscheiden sich von den bisher bekannten ostatlantischen Arten durch eine begeiselte modifizierte Borste an der inneren endstandigen Ecke des Antennulastammes. Im Vergleich zu H. dardani hat H. wirtzi vier anstelle von drei Dornen am Uropoden-Endopoditen und mehr Dornen an den zweiten bis vierten Pleopoden des Mannchens. Morphologische Unterschiede legen nahe, dass Kommensalismen von Heteromysis-Arten mit Einsiedlerkrebsen in den (sub)tropischen Schelfgebieten von Indopazifik, Ostpazifik und Atlantik unabhangig entstanden sind. Die westatlantischen Anemonen-Kommensalen gehoren zu zwei unterschiedlichen morphologischen Linien innerhalb der Untergattung Olivemysis Băcescu, 1968, wobei eine Linie nahere Beziehungen zu den neubeschriebenen ostatlantischen Arten zeigt. Ein Bestimmungsschlussel fur Heteromysis aus Ostatlantik und Mittelmeer wird vorgelegt., Faunistic studies and a survey of anemone commensals in near-shore habitats at the Island of Madeira yielded two new species belonging to the genus Heteromysis: H. dardani commensal with the diogenid hermit crab, Dardanus calidus (Risso, 1827), and H. wirtzi with the sea anemone, Telmatactis cricoides (Duchassaing, 1850). Both species differ from previously known E. Atlantic species by a flagellate, modified seta on the inner distal corner of the antennular trunk. H. wirtzi shows more spines on the second to fourth male pleopods, and four spines on the endopods of the uropods compared to three spines in H. dardani. Morphological differences suggest that commensalism of Heteromysis species with hermit crabs has independently evolved in the (sub)tropical shelf areas of the Indo-Pacific, E. Pacific, and Atlantic oceans. The W. Atlantic anemone commensals belong to two morphologically distinct lines within the subgenus Olivemysis Băcescu, 1968, one of which shows close relationships to the two newly described E. Atlantic species. A key to the species of Heteromysis known from the E. Atlantic and the Mediterranean is given. Faunistische Untersuchungen und eine Erfassung von Anemonen-Kommensalismen entlang der Kusten von Madeira ergaben zwei neue Arten der Gattung Heteromysis: H. dardani, ein Kommensal der Einsiedler-Art Dardanus calidus (Risso, 1827) und H. wirtzi, ein Kommensal der Anemone Telmatactis cricoides (Duchassaing, 1850). Beide unterscheiden sich von den bisher bekannten ostatlantischen Arten durch eine begeiselte modifizierte Borste an der inneren endstandigen Ecke des Antennulastammes. Im Vergleich zu H. dardani hat H. wirtzi vier anstelle von drei Dornen am Uropoden-Endopoditen und mehr Dornen an den zweiten bis vierten Pleopoden des Mannchens. Morphologische Unterschiede legen nahe, dass Kommensalismen von Heteromysis-Arten mit Einsiedlerkrebsen in den (sub)tropischen Schelfgebieten von Indopazifik, Ostpazifik und Atlantik unabhangig entstanden sind. Die westatlantischen Anemonen-Kommensalen gehoren zu zwei unterschiedlichen morphologischen Linien innerhalb der Untergattung Olivemysis Băcescu, 1968, wobei eine Linie nahere Beziehungen zu den neubeschriebenen ostatlantischen Arten zeigt. Ein Bestimmungsschlussel fur Heteromysis aus Ostatlantik und Mittelmeer wird vorgelegt.]

Comparative morphology and actuopalaeontology of mysid statoliths (Crustacea, Mysidacea)

SummaryA comprehensive and comparative study of the external statolith morphology of the family Mysidae is presented. The study covers 48 species from major systematic groups occupying a large number of habitats in different biogeographical zones of the globe. Statoliths generally show high morphological diversity. The traditional classification scheme of subtaxa and the correlation of statolith characters with segmentation patterns of body appendages suggest that the organic composition and the nearly spherical structure of the statoliths of Boreomysinae and Rhopalophthalminae are plesiomorphic compared with the more complex mineralized statoliths found in all other subfamilies. During ontogenetic development the number of sensorial setae and associated pores and pore groups on the statolith increase with body size and statolith diameter. Although patterns of caudal pores are highly specific for some genera, the high intraspecific variance of pore numbers strongly reduces the diagnostic value of this feature in most species. Statolith characters can be successfully used for identification of subfamilies, tribes, and especially genera. For future palaeontological applications a proper diagnosis of fossil mysid statoliths is essential. Therefore, we provide a key to subfamilies and tribes based exclusively on statolith characters.

Freilanduntersuchungen Zur Lebensweise Von Pyroleptomysis r uBra, Einer Neuen Bentho-Pelagischen Mysidacee Aus Dem Mittelmeer Und Dem Roten Meer

Pyroleptomysis rubra is described as a new genus and species of the tribe Leptomysini. Its most prominent distinction from the well established genus Leptomysis is the complete absence of sympod and exopod of the first pleopod of the male. It is suggested that Leptomysis peresi Bacescu, 1966, is to be placed into the new genus. P. rubra breeds throughout the year in the Gulf of Naples, but stops breeding in winter in the North Adriatic. It lives in swarms mainly over rocky substrate in 3 to 25 m depth. The swarms disperse following sunset and reaggregate at sunrise. The animals are unspecialized bentho-pelagic filter feeders with transition to epibenthic detritus feeders.

A New Transoceanic Invasion? First Records of Neomysis americana (Crustacea: Mysidae) in the East Atlantic

First records in the East Atlantic are reported for the North-West Atlantic endemic mysid Neomysis americana (S. I. Smith, 1873), previously known as an invader of South-West Atlantic coasts. Two specimens were caught in 2010 in coastal waters of The Netherlands. The new records provide the first evidence for a west to east transfer of a mysid species across the Atlantic, whereas previously published transfers were observed only in the opposite direction. Major diagnostic characters are reconsidered and the validity of the European species of Neomysis and Acanthomysis is discussed. A pictorial key to these species is given to facilitate future assessments of potential range expansions of N. americana.

Feeding, Reproduction, and Development of the Subterranean Peracarid Shrimp Spelaeomysis bottazzii (Lepidomysidae) from a Brackish Well in Apulia (Southeastern italy)

Abstract A population of the ‘eyeless’ hypogean shrimp Spelaeomysis bottazzii was studied over a three-year period in a shallow brackish-water well about 1 km from the Mediterranean coast. Mature males and immature females were numerous year round, whereas breeding females and juveniles were rare. The main stages of young in the brood pouch were embryos, nauplioids, and postnauplioids; all were unpigmented, unlike the postnauplioids in a congeneric species. In this well, the free-living stages fed mainly on autotrophic micro-organisms. The accumulation of fat reserves was judged from the amount of subcuticular fat bodies and from body colour. Fat status improved with increasing body size in both sexes; seasonal variations were not significant. Only ‘fat’ specimens produced eggs. Females incubating eggs were fatter than those with larvae. Field and laboratory findings suggest that fat accumulation near the photic zone is necessary for egg formation, whereas larval incubation is very long and mostly occurs elsewhere, probably in deep groundwater under unfavourable nutritional conditions. The observed post-reproductive reduction of oöstegites may indicate a peculiar strategy to avoid a new breeding cycle before reconstitution of fat reserves. The findings on feeding and reproduction, particularly regarding fecundity and natality, are interpreted as a combination of typically hypogean features along with epigean environmental adaptations.

A revision of the genus Paraleptomysis Liu & Wang (Crustacea: Mysidacea)

Abstract For four species of Paraleptomysis, revised or new descriptions are given based on type matenal and partly on additional material from a large distribution range. P. banyulensis (BĂCESCU) is elevated to species rank, and a new taxon, P. dimorpha sp.n., from equatorial West Africa is described. One may distinguish two biogeographically definable groups: 1) Atlantic and Mediterranean species, P. apiops, P. banyulensis, and P. dimorpha, with one spiniform projection at sympod of antenna; and 2) eastern Indian Ocean and China Sea species, P. xenops and P. sinensis, with two projections at this sympod.