When invaders meet locally adapted types: rapid moulding of hybrid zones between sculpins (Cottus, Pisces) in the Rhine system

Hybrid zones are commonly studied to dissect the processes that drive divergence among lineages, which have incomplete barriers of reproduction. Most hybrid zones have existed for an extended time making inferences on the initial mode of formation difficult. It is a priori unclear how fast a nascent hybrid zone would form as a response to endogenous and exogenous factors. We have studied several hybrid zones between two lineages of sculpins (Cottus spp.), which emerged due to a recent range expansion of one of the lineages along the river Rhine in the early 1990s. Applying a dense sampling across two contact areas and using a highly informative set of 45 microsatellite markers we found pronounced genetic structure. Steep genetic clines suggest that strong selective forces have shaped the respective hybrid zones from the beginning. We find that the zones are coupled to ecological transitions from small streams to larger rivers. The width of these zones is much smaller than estimates of annual individual dispersal distances, as estimated outside of the hybrid zones. The pattern is apparently not strongly affected by pre- or postzygotic reproductive isolation because numerous backcross hybrids occur within the zones. This suggests that strong natural selection acts against immigrant genotypes. The study exemplifies how local adaptation can play a key role in preventing admixture in dependence of the ecological context.     

Evolutionary history of freshwater sculpins, genus Cottus (Teleostei; Cottidae) and related taxa, as inferred from mitochondrial DNA phylogeny

The freshwater sculpins, genus Cottus (Teleostei; Cottidae), comprise bottom-dwelling fishes that exhibit various life-history styles, having radiated throughout Northern Hemisphere freshwater habitats. The phylogenetic relationships among Cottus and related taxa were estimated from mitochondrial DNA 12S rRNA and control region (CR) sequences, the freshwater sculpins examined falling into five lineages (A-E). Lineage A consisted of Trachidermus fasciatus and C. kazika, both having a catadromous life-history. The remaining species (lineages B-E) spawn in freshwater habitats regardless of life-history (amphidromous, lacustrine or fluvial), suggesting that the various life-history types post-dated a common ancestor of lineages B-E. Molecular clock estimates suggested a Pliocene-Pleistocene radiation (or Miocene-Pliocene from the alternative clock) of lineages B-E. In eastern Eurasia, speciation with life-history changes to amphidromous or fluvial styles has apparently occurred independently in some lineages, as a general pattern. Mitochondrial DNA CR phylogeny showed the monophyletic Baikalian cottoids (Cottoidei) to be nested within Cottus and Trachidermus, suggesting that the former ecologically and morphologically divergent cottoids may have originated from a single lineage which invaded the ancient lake.     

A new species of sculpin Cottus kolymensis sp. nova (Scorpaeniformes, Cottidae) from Rivers of Kolyma

Sculpin from the Kolyma, Dukcha, and Glukhaya rivers is described as a new species Cottus kolymensis from the species group ??Cottus poecilopus??. This species differs from the remaining species of the group (C. altaicus, C. szanaga, C. kuznetzovi, C. koreanus, and C. volki) in the combination of several characteristics: very short internal ray of ventral fin averaging 1/5 of the long ray; comparatively wide interorbital space equal or slightly smaller than longitudinal eye diameter, presence of teeth on palatine bones; as a rule, paired fifth pore of the preoperculo-mandibular canal; and an incomplete lateral canal terminating in two to three autonomous segments and opening by (13 + 2 + 2)-(23 + 2 + 2 + 2) pores.     

Acrossocheilus spinifer, a new species of barred cyprinid fish from south China (Pisces: Teleostei)

Acrossocheilus spinifer sp. nov. is described from the river basins in Fujian Province and the Han Jiang basin in Guangdong Province, south China. It is one of the barred Acrossocheilus species sharing five or six vertical bars on the flanks, with each bar being two scales in width. Acrossocheilus spinifer sp. nov. is morphologically most similar to Acrossocheilus wenchowensis , but distinguished from it by: a colour pattern of all vertical bars extending ventrally to the second scale row below the lateral line, and having the second bar placed posterior to the base of the last simple dorsal‐fin ray, a blunt snout; and a stout, last simple dorsal‐fin ray. Acrossocheilus spinifer sp. nov. resembles Acrossocheilus kreyenbergii and Acrossocheilus stenotaeniatus with which it shares a stout, last simple dorsal‐fin ray with a serrated posterior edge, but is separated from both species by having a narrow median interruption in the lower lip, a lower jaw fully covered by the lower lip when viewed ventrally and the second vertical bar placed posterior to the base of the last simple dorsal‐fin ray. The absence of a longitudinal stripe extending along the lateral line on the flanks in males readily distinguishes A. spinifer sp. nov. from four other species, namely Acrossocheilus fasciatus , Acrossocheilus paradoxus, Acrossocheilus parallens , and Acrossocheilus jishouensis .     

A new sculpin species Cottus sabaudicus sp. nova (Scorpaeniformes: Cottidae) from the Savoy district, France

Sculpins from mountain tributaries of the upper reaches of the Rhone River (Haute-Savoy district) in the collection of the National Museum of Natural History (Paris, France) are described as a new species Cottus sabaudicus. This species belongs to the species group C. gobio, but is characterized by several morphologically specific features. It differs from the typical species of the genus C. gobio in its monotonous body coloration, an increased postanal distance that equals preanal distance, an absence of dark stripes on ventral fins, the ratio of the length of caudal peduncle and depth (1.8–2.3 versus 2.3–2.8), and a greater number of pores in the trunk seismosensory canal (34–37 versus 31–33 + 1).     

Monognathus berteli sp. nov. from the Indian Ocean (Pisces,Monognathidae)

A new deepsea monognathid species,Monognathus berteli, is described based on one specimen collected pelagically in the northwestern Indian Ocean at 1440–1018 meters of depth. LikeM. taningi andM. bertini, it belongs to the short-skulled species-group and has very long pectoral fins, but differs from these species by several meristic characters. The described specimen has a very long caudal filament (53% SL) which is not known from otherMonognathus. However, the fragile filament is not used as a diagnostic character since it could easily be broken.     

Diaphus pallidus sp.n., a new lanternfish from the Gulf of Aden (Pisces, Myctophidae)

A new myctophid species, Diaphus pallidus sp.n., was captured in the Gulf of Aden. The species can be distinguished from most of its congeners by the high number of dorsal fin rays and low number of gill rakers. It can be distinguished from D. lucidus (Goode & Bean) by the form of the operculum and by the situation of some of the body photophores.     

A new genus and species of the family Ipnopidae (Pisces, Teleostei) from the eastern North Atlantic, with notes on its ecology

An additional and hitherto undescribed ipnopid genus and species, Discoverichthys praecox Merrett and Nielsen, is reported and described, and its relationships with the family and aspects of its biology are discussed.     

Parvicapsula bicornis n. sp. and P. limandae n. sp. (Myxozoa, Parvicapsulidae) in Pleuronectidae (Teleostei, Heterosomata) from Denmark

Two species of Parvicapsula were found in the kidney tubules and the urinary bladder of 2 pleuronectid fish from the northern Oresund, Denmark. The coelozoic, spherical, disporic trophozoites of both species are 10 to 12 pm in diameter. The myxospores of both species are elongate, asymmetrical and slightly curved, and have spherical polar capsules. Parvicapsula bicornis n. sp. (6-8 x 5-6 microm, polar capsule 2.5 microm in diameter) occurs in Pleuronectes platessa. The polar capsules of P. bicornis are arranged symmetrically on either side of the longitudinal axis and its spores differ from other species of Parvicapsula in having two 2-3 microm long posterior processes of different length. Parvicapsula limandae n. sp. (8-11 x 4-5 pm, polar capsule 1.6 microm in diameter) is found in Limanda limanda. The polar capsules are arranged along the longitudinal axis. It differs from Parvicapsula unicornis Kabata, 1962, recorded from L. limanda, in the arrangement of the polar capsules and in the absence of a posterior horn-like projection. The phylogenetic relationship between P. bicornis n. sp., P. limandae n. sp. and other Parvicapsula spp. was examined with their partial small subunit rDNA (SSU rDNA) sequences. P. limandae n. sp. and P. asymmetrica appear to be closely related, while P. bicornis n. sp. and P. minibicornis are the most divergent members of the genus.     

A new Sodalis lineage from bloodsucking fly Craterina melbae (Diptera, Hippoboscoidea) originated independently of the tsetse flies symbiont Sodalis glossinidius

Symbiotic bacterium closely related to the secondary symbiont of tsetse flies, Sodalis glossinidius, has been described from the bloodsucking fly Craterina melbae. Phylogenetic analysis of two genes, 16S rRNA gene and component of type three secretion system, placed the bacterium closer to the Sitophilus-derived branch of Sodalis than to the tsetse symbionts. This indicates that the Craterina-derived lineage of Sodalis originated independent of the tsetse flies symbionts and documents the capability of Sodalis bacteria either to switch between different host groups or to establish the symbiosis by several independent events.     

A New Flagship Peritrich (Ciliophora,Peritrichida) from the River Rhine,Germany: Apocarchesium arndti n. sp.

ABSTRACT. We discovered a free‐living peritrich ciliate with outstanding features in the River Rhine. Its morphology and 18S rRNA gene sequence were studied with standard methods. Apocarchesium arndti n. sp. has several peculiarities. (i) There are ordinary zooids, macrozooids, and microzooids, which form a hemispherical rosette on a discoidal base, the stalk dish, locking the ～18 μm wide and up to 2 mm long, spirally contracting colony stalk. (ii) The stalk myoneme is connected only to the microzooids. (iii) A rosette contains up to 50 zooids not connected to each other but individually attached to the stalk dish with the scopula. (iv) The ordinary zooids are epistylidid, trumpet‐shaped (～6:1 length:width), about 180 × 30 μm in size, and have an ellipsoidal macronucleus subapically between oral cavity and dorsal side. (v) The myoneme system of the zooids, which can contract individually, forms a tube‐like structure in the narrow posterior half of the cell. (vi) The silverline pattern belongs to the transverse‐striate type. (vii) The oral apparatus is of usual structure, with kinety 1 of peniculus 3 distinctly shortened proximally. (viii) The 18S rRNA places A. arndti n. sp. as a distinct lineage near Vorticella and Carchesium. These data are used to provide an improved diagnosis of the genus Apocarchesium. Features (i)–(iii) and the molecular data indicate that Apocarchesium could be the type genus of a new peritrich family.     

Haliotrema cupensis n. sp. (Monogenea, Ancyrocephalidae) from a marine gobiid (Teleostei, Perciformes) of the Mediterranean coast

We describe a new ancyrocephalid monogenean, Haliotrema cupensis n. sp., from a marine gobiid, Gobius cobitis (Pallas) from the Mediterranean Sea. This species differs from the other members of the genus by the morphology of the penis and accessory piece, the haptoral ornamentation and by possessing a larger testis. This is the first report of an ancyrocephalid on a marine gobiid and of a Haliotrema species in the Mediterranean Sea.     

Descriptions of Cosmocampus retropinnis sp. n., Minyichthys sentus sp. n. and Amphelikturus sp. (Pisces, Syngnathidae) from the Eastern Atlantic Region

Pelagic juvenile pipefishes, representing three genera previously unrecorded from the eastern Atlantic region, are reported from collections of the 1928–30 DANA expedition. Cosmocampus retropinnis sp. n., with dorsal-fin origin on tail and 6.75–8.0 subdorsal rings (S Morocco to Gambia), Minyichthys sentus sp. n., with patches of spinules on snout and 42 tail rings (W Mediterranean and Atlantic Ocean off N Morocco and Canary Is.), and Amphelikturus sp. (off Sierra Leone) are described and figured. The subgenus Minyichthys Herald and Randall is rediagnosed as a genus characterized, in part, by an 8-rayed caudal fin. A key is provided to the nine genera of Syngnathidae known from the eastern Atlantic region.     

Spontaneous triploidy and NOR activity in Eigenmannia sp. (Pisces,Sternopygidae) from the Amazon basin

The occurrence of a natural triploid among diploid individuals of Eigenmannia sp from the Amazon basin is described. The diploid individuals had 2n=31 and 32 chromosomes, the difference in chromosome number being due to a Robertsonian rearrangement. The triploid individual presented 2n=46 and had two fused acrocentrics. NOR activity was present in the three homologues of triploid and a NOR polymorphism was detected in the triploid and diploids.     

Zamia grijalvensis sp. nov. (Zamiaceae,Cycadales) from Chiapas,Mexico with notes on hybridization and karyology

Zamia grijalvensis, a new cycad species from Chiapas, México, is described and illustrated. This species is similar to Z. lacandona with respect to leaves, but differs in habit, morphology and colour of the female and male cones. The female cone of Z. grijalvensis is reddish brown to orange brown, whereas that of Z. lacandona is dark brown with lighter beige tomentum. The male cone of Z. grijalvensis is erect, whereas that of Z. lacandona is decumbent. The new species may be of natural hybrid origin and is discussed in the light of other findings among cycads. Preliminary diploid chromosome counts for Z. grijalvensis 2n = 19, 20 and karyotypes appear variable, as previously found in its congeners with wide distribution, such as Z. paucijuga and Z. prasina, both of which are characterised by high diploid numbers with a high number of telocentric and few metacentric chromosomes. These changes in chromosome number are probably the result of stressful environmental factors.     

A new threespine stickleback,Gasterosteus nipponicus sp. nov. (Teleostei: Gasterosteidae), from the Japan Sea region

Gasterosteus nipponicus sp. nov. is described from the holotype, 35 paratypes, and 60 additional specimens. The species differs from congeners in the following combination of characters: lateral plates complete, abruptly reducing in size above the anus, depth of lateral plate above the anus < 60 % that of the deepest plate; caudal keels thin, membranous. The new species is distributed in coastal Japan facing the Sea of Japan from Kyushu to Hokkaido Islands, along the Pacific coast of northern Japan from the Chiba Prefecture to Hokkaido, along the Sea of Okhotsk of Hokkaido, west to the southern and eastern coasts of Korean Peninsula, the Maritime Territory and north to Sakhalin Island, Russia.     

Ergasilus thatcheri n. sp. (Copepoda, Poecilostomatoida, Ergasilidae) from the gills of Rhamdia quelen (Teleostei, Siluriformes, Pimelodidae) from southern Brazil

The female of Ergasilus thatcheri n. sp. (Copepoda, Poecilostomatoida, Ergasilidae) is described from the gills of the "jundiá," Rhamdia quelen (Teleostei, Siluriformes, Pimelodidae), from fish ponds in the State of Rio Grande do Sul, Brazil. The new species has a falciform semipinnate terminal seta on the first exopod, which suggests phylogenetic affinity to 10 other congeners, all from fishes of the Amazon Basin. Based on general morphology, the new species shows great similarity to E. callophysus Thatcher and Boeger, 1984, a parasite of another pimelodid fish Callophysus macropterus. Ergasilus thatcheri n. sp., however, can be easily differentiated from E. callophysus in its possession of a more distal sensillum not located on a cuticular elevation, and a row of spinules on the inner margin of the second antennal segment (first endopodal segment).     

Caligus nolani n. sp. (Copepoda: Caligidae), a parasite of Patagonotothen sima (Richardson) (Teleostei: Pisces) from the Falkland Islands,and a note on Clavella bowmani,Kabata, 1963 (Copepoda: Lernaeopodidae)

Both sexes of a new species of parasitic copepod, Caligus nolani (Caligidae: Siphonostomatoida) from the skin of the nototheniid fish Patagonotothen sima from the Falkland Islands, are described. The male differs superficially from the female in having a more rounded cephalothoracic shield, a thinner genital complex and a two-segmented abdomen. C. nolani can be separated from all other species of Caligus by the shapes of the sternal furca and second antenna. Clavella bowmani Kabata, 1963 from P. sima is the first record of this species from the Falkland Islands.