Choanoflagellate lorica construction and assembly: the nudiform condition. II. Acanthoeca spectabilis Ellis

Acanthoeca spectabilis is one of the most common loricate choanoflagellates found in marine biofilms everywhere. However, it is special for two reasons; firstly, it is probably the most distinctive member of the small nudiform clade of loricate choanoflagellates. Secondly, the lorica chamber of Acanthoeca comprises a closely wound left-handed coil of costae that is unique amongst choanoflagellates. Mathematical analysis of the lorica chamber shows that the helical costae undergo two turns. This species, more than any, demonstrates that the helical coiling of costae can only be achieved by a rotational movement generated by the cell during lorica assembly. Comparison of the lorica morphology of Acanthoeca with that of the closely related genus Polyoeca indicates that the helical costae of Acanthoeca are probably homologous with the outer longitudinal costae of Polyoeca. This is unusual because helical costae are usually the innermost layer of costae. However, since there is no 'true' inner layer in the chamber of Acanthoeca the outer layer of costae are adjacent to the cell surface and therefore available for coiling. In contrast to tectiform choanoflagellates, which number more than one hundred species and inhabit a wide variety of microniches, the six known extant nudiform species must either represent a minor evolutionary development or be the remnants of a previously more extensive radiation.     

A Light and Electron Microscopical Investigation of Loricate Choanoflagellates (Choanoflagellida, Acanthoecidae) from the Andaman Sea, SW Thailand and Denmark: Species of Cosmoeca gen. n.

The choanoflagellate genus Cosmoeca gen.n. is characterized by a very regular arrangement of rod-shaped costal strips, forming 9–12 longitudinal costae (each composed of 34 costal strips) and 2–3 transverse costae. Anteriorly the longitudinal costae attach the transverse costae at the joints between neighbouring transverse costal strips. Five species of Cosmoeca are described: norvegica sp.n. (type species; previously referred to as sp. "N"), C. ventricosa sp.n., (C. phuketensis sp.n., C. subulata sp.n. and C. ceratophora sp.n. Cosmoece ventricosa sp.n. is obviously part of from complex, the extent of which has not yet been fully explained. In this paper, three groups of specimens clearly related to C. ventricosa sp.n. are illustrated and briefly described ( C. ventricosa forms A. B, C). Form A appears to be identical to Pleurasiga orculaeformis Schiller, 1925, sensu Leadbeater.     

A new delthyridoid spiriferid genus from the Dra Valley, Morocco, and its phylogenetic affinities (Brachiopoda, Lower Devonian)

Multiplicatispirifer, a new delthyridoid brachiopod genus with a gently divergent capillate micro-ornamentation and bifurcating costae on flanks, sulcus and fold, has been identified in the Mdâouer-el-Kbîr Formation of the Dra Valley (southern Anti-Atlas, Morocco). Its type speciesMultiplicatispirifer foumzguidensis n. gen., n. sp., at present the only species of this genus, is described. This form has hitherto been determined asFimbrispirifer orStruveina by various authors. In this work, the new genus is compared with the multiplicate and capillate spiriferid genera with bifurcating costae which also have costae in the sulcus and on the fold:Costispirifer andPerryspirifer from North America,Elymospirifer from South China,Borealispirifer from Asia andMultispirifer from Central Europe. The relation ofMultiplicatispirifer to the fimbriateFimbrispirifer, Struveina andVandercammenina, from which it is distinguished by its capillate micro-ornamentation, is discussed. The new genus is hitherto only known from the Moroccan southern Anti-Atlas. Its colsest relatives, taxa ofCostispirifer, occur in the Eastern American Realm (Gaspé, Canada and the eastern United States) and the Nevada Province (western United States).Multiplicatispirifer occurrences are restricted to the Lower/Upper Emsian boundary interval (upper Lower Devonian). The reasons for a possible migration corridor between North America and North Africa before Emsian time are discussed.     

Kakoeca antarctica gen. et sp.n., a loricate choanoflagellate (Acanthoecidae, Choanoflagellida) from Antarctic sea ice with a unique protoplast suspensory membrane

A new genus and species of loricate choanoflagellate, Kakoeca aniarctica Buck & Marchant gen. et sp.n. grown in rough culture from an Antarctic sea ice innoculum is described. This organism has a distinctive lorica morphology consisting of more than 200 costal strips arranged in transverse and longitudinal costae that arc perpendicular to one another in the posterior portion of the lorica. The transverse costae show declination with respect to the lorica axis in the anterior part of the lorica. The cell is suspended in the lorica by a robust protoplast suspensory membrane. This membrane blocks water flow from the posterior of the lorica necessitating water entry through the side of the lorica, an area where the maximum sized apertures in the lorica are found. Terminology (lorica lining and protoplast suspensory) is suggested for the two types of lorica membranes which have been found associated with loricas.     

Acanthocorbis mongolica nov. spec.: description of the first freshwater loricate choanoflagellate (Acanthoecida) from a Mongolian lake

A new acanthoecid choanoflagellate species, Acanthocorbis mongolica sp. nov. was found in preserved phytoplankton samples from the freshwater lake Bayan Nuur (Uvs Nuur Basin, NW Mongolia) in concentrations of up to 1.8×10(5)cellsL(-1). It is the first well-documented species of the mainly marine order Acanthoecida to be found in a freshwater lake. The lorica structures were studied with scanning electron microscopy. Key morphological features of the vase-shaped lorica are spine bases that are composed of multiple (2-4) parallel costal strips, and the existence of two transverse costae. The ecological implications of this find are discussed.     

A new genus and two new species of Peltogastridae (Crustacea: Cirripedia: Rhizocephala) parasitizing hermit crabs from Okinawa Island (Ryukyu Archipelago, Japan), and their DNA-barcodes

A new genus and two new species of Peltogastridae, Peltogaster postica sp. nov. and Ommatogaster nana gen. et sp. nov., are described from Okinawa Island, Ryukyu Islands, southwestern Japan. The two new rhizocephalans were found to be parasitic on the estuarine hermit crabs, Pagurus minutus Hess, 1865 and Diogenes leptocerus Forest, 1956, respectively. Peltogaster postica sp. nov. is allied to P. curvata Kossmann, 1874, P. paguri Rathke, 1842 , and P. reticulata Shiino, 1943 , but is distinguished by its relative length and internal and external structures of the mature externa. Ommatogaster gen. nov. is established for the present new species O. nana based on the morphologies of the visceral mass of the externa and the presence of a nauplius eye in the larvae. Partial COI sequences were obtained from the two new species and one known species, Dipterosaccus indicus Van Kampen and Boschma, 1925, to test the possible usefulness of the sequences as tags for species identification.     

The Geonemertes problem (Nemertea)

A new genus of monostiliferous hoplonemerteans, Pantinonemertes gen. nov., provides evidence for the separate evolution of terrestrial nemerteans. The genus is established for two new species found in Australia, P. enalios sp. nov., an intertidal form, and P. winsori sp. nov., which lives in fallen timber in the supralittoral brackish water regions of mangrove swamps. One only of the known species of land nemerteans, Geonemertes agricola from Bermuda, closely resembles these two species morphologically and is transferred to the new genus as Pantinonemertes agricola .
A re-examination of all the known species of Geonemertes has shown that two major groups can be distinguished on the basis of morphological characters. In one group the rhynchocoel musculature is in two distinct layers, a frontal organ is present, the mid-dorsal blood vessel has a single vascular plug, and the flame cells are binucleate and reinforced with cuticular support bars. It comprises the genus Pantinonemertes gen, nov, and the Pelaensis or Indopacific group of terrestrial nemerteans, for which the generic name Geonemertes is retained. In the second major group the rhynchocoel musculature is composed of interwoven longitudinal and circular fibres, there is no frontal organ, the mid-dorsal blood vessel bears two vascular plugs, and the flame cells are mononucleate and lack support bars. Five genera, three of which are new, are distinguished in this group. Australian species are united in the genus Argonemertes gen. nov., and New Zealand forms comprise the genus Antiponemertes gen. nov., while Acteonemertes bathamae from New Zealand and the Auckland and Ocean Islands remains in a separate genus. Geonemertes nightingaleensis is transferred to a new genus, Katechonemertes gen. nov., and for Geonemertes chalicophora a previously used generic name, Leptonemertes , is adopted.
A key to the terrestrial, brackish-water and marine nemertean species described in the present paper is provided.     

Piscirickettsia salmonis gen. nov., sp. nov., the causative agent of an epizootic disease in salmonid fishes.

A novel intracellular pathogen morphologically similar to the ehrlichiae has been isolated in cell culture and identified as the cause of an epizootic disease of salmonid fish. Like the ehrlichiae, the salmonid pathogen, designated strain LF-89, replicates within membrane-bound cytoplasmic vacuoles in host cells. This agent is the first with characteristics of this type to be isolated from a fish. Analysis of the LF-89 16S rRNA indicated that, unlike the ehrlichiae, LF-89 is a gamma proteobacterium distantly related to Coxiella burnetii and perhaps Wolbachia persica. A new genus and species (Piscirickettsia salmonis gen. nov., sp. nov.) are proposed for this organism, with ATCC(R) VR 1361 as the type strain.     

A new genus and two new species of Aporhynchidae (Cestoda: Trypanorhyncha) from catsharks (Carcharhiniformes: Scyliorhinidae) off Taiwan

New collections of cestodes from the spiral intestines of catsharks (Carcharhiniformes: Scyliorhinidae) off Taiwan have led to the discovery of a new genus and 2 new species of trypanorhynchs. These taxa are relatively unique among trypanorhynchs in their lack of all elements of the rhyncheal apparatus. The new genus, Nakayacestus n. gen., is considered to belong with Aporhynchus in the Aporhynchidae. In addition to lacking the rhyncheal apparatus, these 2 genera share circum-medullary vitelline follicles, post-ovarian testes, and complex terminal genitalia consisting of accessory, external, and internal seminal vesicles. The 2 genera differ conspicuously in spinithrix configuration; whereas both species of Nakayacestus n. gen. bear scolex spinitriches that are bifid, trifid, or pectinate, species of Aporhynchus either lack scolex spinitriches entirely or possess spathulate spinitriches. The configuration of the bothria of the 2 genera also differ conspicuously. Whereas the bothria of Aporhynchus are sessile and generally do not extend beyond the lateral margins of the cephalic peduncle, those of Nakayacestus bear only a tenuous connection with the scolex proper, being conspicuously free both anteriorly and posteriorly and extending conspicuously beyond the cephalic peduncle. Futhermore, the boundary between the scolex and the strobila of members of the new genus is clearly delineated, whereas this distinction is ill-defined in species of Aporhynchus. Nakayacestus takahashii n. sp., the type of the new genus, was collected from the Broadmouth catshark, Apristurus macrostomus, and differs from Nakayacestus tanyderus n. sp., collected from the Blacktip sawtail catshark, Galeus sauteri, in being shorter, bearing a longer pedunculus scolecis, an ovary that is more posterior in the proglottid, and fewer post-ovarian testes. Furthermore, the 2 new species differ conspicuously from one another in the configuration of their scolex spinitriches.     

MUSOPSIS N. GEN.: A BANANA-LIKE LEAF GENUS FROM THE EARLY TERTIARY OF EASTERN NORTH GREENLAND

A fossil flora from the Late Paleocene-Early Eocene Thyra Ø Formation of eastern North Greenland (paleolatitude 77° N) has yielded monocotyledon leaf impressions with characters seen only in the closely related modem species in the families of Heliconiaceae, Musaceae, and Strelitziaceae. The combination of large costae widths and parallel, nonanastomosing, lateral veins that depart at right angles from the costae in the fossil material are features present only in leaves of extant species from these families. Three basic venation patterns also are recognized in the modem species of these families, but except for the genera Strelitzia and Phenakospermum, none of these patterns are present exclusively in any one family. Musopsis n. gen. is created for the fossil material from Greenland, but it is considered a form genus due to the lack of gross morphological features that can be used for separating leaves of the modem genera in Heliconiaceae, Musaceae, and Strelitiziaceae. It is the first known Arctic occurrence of fossil leaf material resembling this modem group of taxa.     

Choanoflagellates (Sarcomastigophora, Protozoa) from the Coastal Waters of Taiwan and Japan. I. Three New Species

Three new acanthoecidaean species collected from the coastal waters of Taiwan and Japan are described: Acanthocorbis camarensis n. sp. resembles Acanthocorbis unguiculata in lorica morphology, but differs in having regularly arranged longitudinal and transverse costae at the anterior lorica chamber, and in lacking a nail at the apical end of anterior spine; Diaphanoeca spiralifurca n. sp. is characterized by the spiral arrangement of the costal strips in the posterior half of the lorica chamber and is closely related to Diaphanoeca grandis; Stephanoeca supracostata n. sp. is closely related to Stephanoeca elegans, but differs in having an additional transverse costa at the anterior lorica chamber.     

Isolation of a new heterolobosean amoeba from a rice field soil: Vrihiamoeba italica gen. nov., sp. nov.

A heterolobosean amoeba strain 6_5F was isolated from an Italian rice field soil. Although 18S rRNA gene sequence analysis demonstrated that the new isolate was closely related to Stachyamoeba sp. ATCC 50324, further molecular analysis and morphological observation showed distinct differences amongst the two. The 5.8S rRNA gene was successfully amplified and sequenced for strain 6_5F but not for strain ATCC 50324. Trophozoites of strain ATCC 50324 transform into flagellate forms in the late stage of incubation before encystment, while strain 6_5F do not show flagellate forms under different conditions of the flagellation test. Light and electron microscopic observation showed the structural difference of cysts of strain 6_5F from strain ATCC 50324 and also from the type strain Stachyamoeba lipophora. The results show that the strain 6_5F is distinct from Stachyamoeba spp. and we propose a new genus and species for this isolate, Vrihiamoeba italica gen. nov., sp. nov.     

Neosychnocotyle maggiae, n. gen., n. sp. (Platyhelminthes: Aspidogastrea) from freshwater turtles in northern Australia

Neosychnocotyle maggiae, n. gen., n. sp., (Aspidogastrea) is described from the pig-nosed turtle, Carettochelys insculpta, and reported from the Victoria River red-faced turtle, Emydura victoriae, all from the Daly River, Northern Territory, Australia. Neosychnocotyle n. gen. is differentiated from all aspidogastrean genera but one by the absence of a cirrus sac. The similar Sychnocotyle also lacks a cirrus sac, but Neosychnocotyle n. gen. differs from the former genus by possessing a narrow, tapered anterior end, a ventral disk that covers the posterior end of the body, a genital pore that is displaced anteriorly, and a vas deferens that is less convoluted and less robust. Analysis of ribosomal DNA sequences demonstrates substantial sequence variability between representatives of Sychnocotyle and Neosychnocotyle maggiae, n. gen., n. sp. It is possible that this new parasite may reach sexual maturity only in C. insculpta. This is only the second aspidogastrean species reported from Australian freshwater turtles.     

Morphological and molecular reinvestigation of acanthoecid species III. – Kalathoeca cupula (Leadbeater, 1972) gen. et comb. nov. (=Stephanoeca cupula (Leadbeater) Thomsen, 1988)

Based on a further re-examination of loricate choanoflagellate species with detailed morphological (SEM/TEM) and molecular data of the SSU and LSU rRNA, the present study aims to give new insights for Stephanoeca cupula. In contrast to the original allocation within the family of tectiform reproducing species, morphological and molecular data of S. cupula sensu Leadbeater, 1972 points towards an affiliation within the nudiform reproducing family. Based on these new data, we here erect the nudiform genus Kalathoeca with its type species K. cupula gen. et comb. nov. Our data challenges morphological species assignments, as K. cupula shares its morphological lorica characteristics with tectiform reproducing species of Stephanoeca sensu stricto. Kalathoeca cupula is an interesting candidate for further investigating and understanding the evolutionary relationship of tectiform and nudiform reproducing species.Stephanoeca cupula sensu Thomsen, 1988 has been morphologically re-examined based on the renewed understanding of the morphological variability associated with S. cupula sensu Leadbeater, 1972 (=K. cupula), allowing us now to distribute the different morphological forms investigated within K. cupula and Pseudostephanoeca quasicupula.     

A rearrangement of the family Tethyidae (Porifera Hadromerida) with establishment of new genera and description of two new species

The discovery of new species, a study of the type material of already described species and an analysis of the literature data call for an extensive rearrangement of the Family Tethyidae, whose last revision dates from Burton (1924). The rearrangement proposed here attributes to the Family eight genera: Tethya Lam. (type genus), Burtonitethya gen nov. , Columnitis Schmidt, Halicomeies Topsent, Stellitethya gen. nov., Tectnitethya gen. nov., Tethycometes gen. nov . and Xenospongia Gray. The genus Aaptos is excluded from the Tethyidae. Three of the new genera have been established for species previously attributed to the genus Tethya and two are new: Burtonitethya gemmiformis (Burton & Rao) and Tethycometes sibogae sp. nov . Five species, previously attributed to Tethya , are considered 'incertae sedis'. An analytical key and discussion of the evolution of the family are included.     

First description of an euryoecious acanthoecid choanoflagellate species,Enibas tolerabilis gen. et sp. nov. from a salar in the Chilean Andes based on morphological and transcriptomic data

In general, acanthoecid choanoflagellates have been described to occur exclusively in brackish water to marine habitats. Only recently, two studies have proven their existence in inland waters. One of them has shown, that an acanthoecid species from a small lake (near Apia on the island of Upolu, Samoa) is strictly freshwater adapted, not able to tolerate even brackish water. In this study, we present the first euryoecious acanthoecid species, able to live and reproduce in freshwater as well as under hypersaline conditions. The new species, Enibas tolerabilis gen. et sp. nov. was isolated in 2017 from the Salar de Ascotán in the Altiplano at 3750 m a. s. l., Northern Chile. The salinity at the time of sampling was 6 PSU. A series of autecological experiments have revealed a salinity tolerance from freshwater up to 70 PSU. In our phylogenetic analysis, E. tolerabilis gen. et sp. nov. clustered within the family of Acanthoecidae, forming a well-supported sister clade together with two other, environmental choanoflagellate sequences. We erected a new genus, Enibas gen. nov. and described the morphology, molecular biology and autecology for E. tolerabilis gen. et sp. nov. which has a stephanoecid-like lorica morphology. We emphasize that the definition of the genus Stephanoeca, being polyphyletic, is in urgent need of revision as we showed that this morphology is present in both acanthoecid families.     

Oramoeba fumarolia gen. nov., sp. nov., a new marine heterolobosean amoeboflagellate growing at 54 °C

An amoeba strain was isolated from marine sediment taken from the beach near a fumarole in Italy. The trophozoites of this new marine species transforms into flagellates with variable numbers of flagella, from 2 to 10. The strain forms round to oval cysts. This thermophilic amoeboflagellate grows at temperatures up to 54 °C. Molecular phylogenetic analysis of the small subunit ribosomal DNA (SSU rDNA) places the amoeboflagellate in the Heterolobosea. The closest relatives are Stachyamoeba sp. ATCC50324, a strain isolated from an ocean sample, and Vrihiamoeba italica, a recent isolate from a rice field. Like some other heterolobosean species, this new isolate has a group I intron in the SSU rDNA. Because of the unique place in the molecular phylogenetic tree, and because there is no species found in the literature with similar morphological and physiological characteristics, this isolate is considered to be a new genus and a new species, Oramoeba fumarolia gen. nov., sp. nov.