Factors influencing latitudinal pattern of biodiversity: An example using Sabellidae (Annelida, Polychaeta)

The latitudinal gradient of biodiversity hypothesis was tested utilising the geographical distribution of species taxa belonging to the family Sabellidae (Annelida: Polychaeta), one of the polychaete families studied by only a few specialists around the world. An increase in species richness towards the Tropical region was revealed, with an asymmetric distribution between the two hemispheres. Data show that most of the species were found in Northern latitudes, producing a Northern area much richer than the Southern one. The Atlantic-Mediterranean Region was particularly rich, with the number of species close to those from the Indo-Pacific Region. Mediterranean species richness is discussed in the light of the particular history of the basin, also emphasising the importance of naturalistic studies that have made the Mediterranean marine flora and fauna one of the best known in the world. The existence of extrinsic factors that obscure the real pattern of distributions is hypothesised. Differences found between the two hemispheres could be attributed primarily to the higher number of specialists working in the Boreal Domains, including the Mediterranean area. Global trends produced by some representative genera are also discussed with respect to the distribution of the taxonomic specialists.     

Further revisions of the Sabellidae subfamilies and cladistic relationships among the Fabriciinae (Annelida: Polychaeta)

Cladistic relationships of the sabellid subfamilies Fabriciinae and Sabellinae are examined in light of recent revisions of fabriciin taxa. The potential placement of Caobangia in the Sabellinae is suggested from an initial analysis of selected fabriciin species and genera. Subsequent cladistic analyses at the family level produced over 1800 cladograms, among which Caobangia is the most plesiomorphic taxon of either the Fabriciinae or Sabellinae. Successive approximations weighting reduced this ambiguity, consistently placing Caobangia in the Sabellinae. Subfamilies are emended on the basis of these results. Cladistic relationships of fabriciin taxa, exclusive of Caobangia , display topological instability among some genera and species. Genera are, however, monophyletic in all topologies. Incorporating ontogenetic data for branching ventral filamentous appendages in Augeneriella reduces ambiguity among genera and suggests alternative transformation series for ventral filamentous appendages.     

Capitellidae (Annelida: Polychaeta) from the Pacific Coast of Costa Rica

Eleven species of Capitellidae (Annelida: Polychaeta) belonging to eight genera are reported from the subtidal and intertidal of the Pacific Coast of Costa Rica. Three species, Mediomastus ambiseta, M. californiensis and Notomastus hemipodus, are found in highest abundances and are widespread in subtidal and intertidal environments. A taxonomic key to these species is included.     

Parvicapsula minibicornis in anadromous sockeye (Oncorhynchus nerka) and coho (Oncorhynchus kisutch) salmon from tributaries of the Columbia River

The myxosporean parasite Parvicapsula minibicornis is described from adult sockeye and coho salmon during spawning migrations in tributaries of the Columbia River in Canada and the United States. These observations extend the known distribution of this parasite from the Fraser River drainage basin. The parasite was identified in Columbia River salmonids using polymerase chain reaction (PCR) and by in situ hybridization, but unlike in Fraser River salmon, it was not observed in conventional histological preparations of the kidney. Prevalence of the parasite determined by PCR was higher in spawning sockeye from the Fraser River than in those from the Okanagan River. Our ability to explain the relatively low prevalence and absence of clinical P. minibicornis infections in Columbia River salmon is hampered by our poor understanding of the life cycle of this parasite.     

Distribution of Streblospio benedicti (Webster, 1879) and Manayunkia aestuarina (Bourne, 1883) (Annelida: Polychaeta) in the Vistula Lagoon of the Baltic Sea

The polychaetes Streblospio benedicti (Webster, 1879) and Manayunkia aestuarina (Bourne, 1883) have been recorded in the Vistula Lagoon of the Baltic Sea since the mid 1990s. The impact that salinity and the necrozooplankton (dead plankton) concentration in the near-bottom layer have on their distributional patterns was studied. The spatial distribution of these polychaetes depends on the water salinity; however, no correlation was found between their abundance and the necrozooplankton concentration. An area of high necrozooplankton concentration was defined for the near-bottom water layer in the central part of the lagoon; its position is mostly determined by the currents. We assume that the sustainable presence of S. benedicti and M. aestuarina is supported by their opportunistic species biology patterns and the lagoon hydrology, even in the last decade of unfavorable water mineralization conditions.     

Distribution and abundance of the salmonid parasite Parvicapsula minibicornis (Myxozoa) in the Klamath River basin (Oregon-California, U.S.A.)

The distribution and abundance of the myxosporean parasite Parvicapsula minibicornis in the Klamath River mirrored that of Ceratomyxa shasta, with which it shares both its vertebrate and invertebrate host. Assay of fish held at sentinel sites and water samples collected from those sites showed that parasite prevalence was highest below Iron Gate dam, which is the barrier to anadromous salmon passage. Above this barrier parasite levels fluctuated, with the parasite detected in the free-flowing river reaches between reservoirs. This was consistent with infection prevalence in the polychaete host, Manayunkia speciosa, which was greater than 1% only in populations tested below Iron Gate dam. Although a low prevalence of infection was detected in juvenile out-migrant fish in the Trinity River, the tributaries tested did not appear to be a significant source of the parasite to the mainstem despite the presence of large numbers of infected adult salmon that migrate and spawn there. Rainbow trout became infected during sentinel exposure, which expands the host range for P. minibicornis and suggests that wild rainbow trout populations are a reservoir for infection, especially above Iron Gate dam. High parasite prevalence in the lower Klamath River is likely a combined effect of high spore input from heavily infected, spawned adult salmon and the proximity to dense populations of polychaetes.     

The Freshwater co-occurrence of Eurytemora Affinis (Copepoda: Calanoida) and Manayunkia Speciosa (Annelida: Polychaeta): Possible relicts of a marine incursion

The copepod Eurytemora affinis (Poppe, 1880) and the polychaete Manayunkia speciosa Leidy, 1858 have been found in similar habitats within the Ottawa River. As both species show strong marine affinities and co-occurrence is not restricted to the Ottawa River, but rather is the pattern for North America, present evidence supports the theory that these animals may be relict forms resulting from the most recent marine incursion.

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Resumé Le copepode Eutytemora affinis (Poppe, 1880) et le polychete Manayunkia speciosa Leidy, 1858 ont étés trouvé en pareils habitats dans la Rivière Ottawa. Comme les deux espèces demontrent de grades affinités marines et ne sont pas restreintes à apparaître ensemble dans la Rivière Ottawa, mais plutôt suivent le patron de l'Amérique du Nord, la preuve présentée appuit la théorie que ces animaux purrainent être des formes reliques resultant de l'incusrion marine la plus récente.

     

Contributions to the taxonomy of Sabellidae (Polychaeta)

The genus Potamilla Malmgren is particularly characterized by dorsal lips which lack any radiolar midrib; Pseudopotamilla Bush by compound radiolar eyes, dorsal collar lappets and flanges alongside the bases of the most dorsal radioles; Demonax Kinberg by a wide dorsal collar gap and companion setae with big heads and narrow blades; and Potamethus Chamberlin by an elongated first segment, enlarged ventral sacs, very long shafts to the thoracic uncini, and inferior abdominal setae much shorter than the superior ones. Perkinsiana gen. nov . lacks most of these characters, but the type species 'Potamilla' rubra Langerhans is remarkable in having red blood. It bores into limestone abundantly off S Wales and is here redescribed. Oriopsis hynensis sp. nov . from SW Ireland has a smooth collar set low on the first segment, with its ventral margin entire and free from the apex of the peristome. The new name Demonax langerhansi is proposed for Sabella (Potamilla) incerta Langerhans non Demonax incertus Kinberg.     

Parasabella Bush, 1905, replacement name for the polychaete genus Demonax Kinberg, 1867 (Annelida, Polychaeta, Sabellidae)

Parasabella Bush, 1905 is reintroduced as a replacement name for Demonax Kinberg, 1867 (Annelida: Polychaeta: Sabellidae) which is a junior homonym of Demonax Thomson, 1860 (Insecta: Coleoptera: Cerambycidae).     

A revision of Sabella, Bispira and Stylomma (Polychaeta: Sabellidae)

Sabella is rediagnosed to include only species that have spiralled fascicles of abdominal chaetae, first thoracic shield with straight anterior border and radioles that lack composite eyes and flanges. Spirographis spallanzanii is synonymous with Sabella penicillus . The type of the genus is discussed and a neotype designated. The only other species retained in Sabella are S. pavonina and S. discifera ( = Branchiomma linaresi , once misplaced in Megalomma , but abdominal fascicles of Megalomma form transverse rows). Most species formerly placed in Sabella are transferred to Bispira , having C-shaped fascicles of abdominal chaetae, first thoracic shield with a 'W-shaped anterior border and, in most species, radioles with paired composite eyes and flanges. Bispira , with B. volutacornis as the type species, is rediagnosed to include B. crassicomis, B. fabricii, B. melanostigma, B. tricyclia, B. viola, B. manicata, B. poricfera, B, mariae, B. elegans, B. brunnea, B. guinensis, B. secusolutus, B. wireni, B. oatesiana, B. spirobranchia, B. pacifica, B. monroi , and B. turneri , many of which are described fully for the first time. Only five of these form bispiral crowns (bispirality is useful only specifically and occurs in other genera) and one, B. tricyclia , has a unispiral crown. Sabella palmata Quatrefages, the type of Stylomma is redescribed and its synonyms discussed. This genus has abdominal fascicles like those of Bispira , but radiolar eyes like those of Megalomma . The relative advantages of chaetal arrangement and eye position are discussed.     

Phylogenetic affinities of the Flabelligeridae (Annelida, Polychaeta)

Cirratuliformia includes Acrocirridae, Cirratulidae, Ctenodrilidae, Flabelligeridae, Flotidae and Sternaspidae. The phylogenetic affinities have not been settled due to a limited availability of type or non-type material and the relationship between acrocirrids and flabelligerids have been problematical. In our study, the type material of all type species for all flabelligerid, and most acrocirrid genera have been studied and the morphological features have been used in a phylogenetic analysis. The results indicate that Acrocirridae, Ctenodrilidae, Fauveliopsidae, Flabelligeridae and Flotidae are monophyletic and that Sternaspidae falls within Cirratulidae; however, the latter conclusion might be reversed through increased taxon-sampling. The flabelligerid genera Brada, Flabelligera, Pherusa and Stylarioides each consists of several monophyletic groups and may be split. Conversely, Bradiella includes Diversibranchius, and the pelagic Buskiella includes Flota. The generic affinities of Poeobius remain uncertain, collecting better materials may resolve this issue.     

Revision of the Fabriciinae genus Fabriciola Friedrich, 1939 (Polychaeta: Sabellidae)

The Sabellidae polychaete genus Fabriciola Friedrich is revised as a result of examination of as much of the type material as possible. The type species for the genus has been confused. The earliest designation appears to be Fabricia (Manayunkia) spongicola Southern, 1921, by Ushakov [ Akad. Nauk. SSSR, Opredeliteli po Faune SSSR 56: 1–445 (1955)], whereas subsequent works have incorrectly referred to Manayunkia pacifica Annenkova, 1934, as the type species. The following species are redescribed: Fabriciola baltica Friedrich, 1939, F. berkeleyi Banse, 1956, F. ghardaqa Banse, 1959 a . A new species, F. mediaseta, is described. A neotype is designated for F . baltica. Existence of the type material of F. spongicola (Southern), F. pacifica (Annenkova), and F. tonerella Banse, 1959 b is unknown, but these species are discussed in relation to species examined.     

Coelomocytes of Nephtys coeca (Annelida,Polychaeta)

Coelomocytes of Nephtys coeca were studied by transmission electron microscopy. The majority of the coelomocytes were found to be structurally identical with the muscle cells of the body wall. Animals kept under unfavourable conditions tended to have an increased number of coelomocytes and a decreased thickness of the body wall. The muscular coelomocytes, probably released from the body wall, showed various degrees of decomposition, indicating a process of autophagy.     

Generic interrelationships within the Spionidae (Annelida: Polychaeta)

The phylogenetic relationships of spionid genera are estimated from parsimony analyses of morphological characters, with Trochochaetidae, Poecilochaetidae and Uncispionidae as outgroups. A first analysis of currendy recognised genera proved inconclusive and even exclusion of six of the most polymorphic genera resulted in 13 305 equally parsimonious trees and a fully collapsed consensus tree. A second analysis using only the type species of each genus, yielded four equally parsimonious trees; reduced to two after successive weighting. The topologies of these two trees indicated division of the family into four main groups: (1) Aonidella and Xandaros; (2) Prionospio (sensu fato)-complex, Laonice, Spiophanes and Aonides; (3) a large assemblage of genera, including Polydora-{senm late), Scolelepis, Malacoceros and Spio; (4) Atherospio, Pseudatherospio and Pygospiopsis. Earlier literature classifications of the group are evaluated and compared with die new results.     

Giant pelagic larvae of Phyllodocidae (Polychaeta,Annelida)

The microscopic anatomy of giant pelagic larvae of Phyllodocidae was studied using routine histological, SEM, and TEM techniques. The larvae consist of two distinct regions: a large spherical trochophore measuring up to 2 mm in diameter and a posterior, long (up to 10 mm length), narrow rudiment of the adult body with up to 120 segments. The larvae have an unusual mixture of larval and adult features, including a very complex, well-developed brain and ganglia in the ventral nerve cord, and only a single pair of protonephridia located in the hyposphere of the trochophore. A muscular pharynx is not developed. The intestinal wall, especially in the trochophore region, consists of endodermal cells containing considerable nutritive material in the form of yolk-like globular inclusions. The digestive tract of all larvae was empty. The position of the frontal sensory organ and the prototroch, the structure of the parapodia and setae, and the three pairs of tentacular cirri dictate inclusion of the larvae in the family Phyllodocidae. The relatively enormous size and unusual pattern of development of the adult body may be adaptations for a long pelagic life and rapid settlement of the species, which inhabits slopes of islands and underwater mounts located far apart. J. Morphol. 238:93–107, 1998. © 1998 Wiley-Liss, Inc.     

Three new deep-sea species of Sphaerodoridae (Annelida,Polychaeta) from the eastern tropical South Pacific*

Three sphaerodorid species new to science are described from a manganese nodule area in abyssal depths of around 4150 m in the Peru Basin in the eastern South Pacific. Sphaerodoridium campanulata sp. n. is isolated within the genus, having, apart from spherical macrotubercles, additional dorsal stalked bell-shaped papillae, not previously described. Sphaerodoropsis discolis sp. n. is a species with four rows of dorsal macrotubercles and two pairs of lateral antennae. Sphaerodoropsis translucida sp. n. has six to seven rows of dorsal macrotubercles arrayed in two transverse rows per segment and two pairs of lateral antennae. A brief discussion points to the close relationship between Clavodorum and Sphaerodoridium, and to the present state of Sphaerodoropsis, being inhomogeneous in the characters of the arrangement of the dorsal macrotubercles and the numbers of the lateral antennae. An overview on the latter genus, with an attempt to subdivide it, is given.     

Ultrastructure of spermiogenesis, sperm, and the spermatheca in Terebrasabella heterouncinata (Polychaeta: Sabellidae: Sabellinae)

Abstract. The sabellid polychaete, Terebrasabella heterouncinata, forms burrows in gastropod shells. It is a small, intratubular brooder that breeds semi‐continuously. It has been shown to self‐fertilize, but its reproductive biology suggests that some form of sperm transfer must occur between individuals. To gain an understanding of its fertilization biology, the ultrastructure of spermiogenesis and the sperm in T. heterouncinata was described, and the animal examined for sperm storage structures. Spermiogenesis occurs in clusters of eight spermatids. The mature sperm has an elongate nucleus and a bilaterally symmetrical acrosome with twisted subacrosomal spaces. The midpiece is short, with three crescent‐shaped mitochondria, and forms a tight sheath around the axoneme. A single spermatheca, which opens on the inner ventral part of the crown near the buccal region, is present. It is a simple blind‐ending duct that runs below the ventral nerve cord and is longer than 100 μm. This is the first record of a single spermatheca in Sabellidae. The shape of the sperm and the presence of a spermatheca confirm that individuals of T. heterouncinata produce ent‐aquasperm and would normally cross‐fertilize.