Phylogenetic relationships of Mediterranean black corals (Cnidaria : Anthozoa : Hexacorallia) and implications for classification within the order Antipatharia

The Mediterranean black coral fauna includes type species of four antipatharian genera belonging to four different families, therefore phylogenetic studies hold great potential for enhancing systematics within the order. The analysis of six Mediterranean antipatharian species by means of nuclear sequence data of internal transcribed spacer (ITS1 and ITS2) rDNA confirms the separation into different families, as was previously noted on a morphological basis, with a clear distinction of the family Leiopathidae, whose position is supported by a unique number of mesenteries and lack of spines on thicker ramifications. The position of a newly recorded black coral species for the Mediterranean basin belonging to the genus Phanopathes is discussed. Antipathes dichotoma, the type species of the genus Antipathes, on which the order Antipatharia was based, does not group with other members of the family Antipathidae. Supporting a recent finding based on mitochondrial markers, this suggests a critical need for revision of the families that will be impacted by reassignment of this nomenclaturally important taxon.

Morphological and molecular characterisation of Longidorus pinus sp. n. (Nematoda: Longidoridae) from China and a key to known species of Longidorus in China

Summary Longidorus pinus sp. n. from China is characterised by females 3.3-4.9 mm long; lip region 8-12 μm diam., distinctly offset by a constriction; amphidial fovea pocket-shaped without basal lobes; a short odontostyle (67-81 μm); anteriorly located guide ring (30-38 μm); and short and conoid tail (31-40 μm long, c = 84-138, c′ = 1.2-1.9), with one or two pairs of caudal pores on each side. Males were not found. Three developmental juvenile stages were identified, the first-stage juvenile with conoid tail (c′ = 2.4-2.9). The polytomous key codes for the new species are: A2(3), B1, C23, D4, E1, F2, G23, H23, I1, J2, K6. Molecular phylogenetic analyses based on SSU, D2-D3 of LSU, ITS1 and ITS2 rDNA sequences indicate that L. pinus sp. n. is closely related to L. hangzhouensis, L. asiaticus, and L. camelliae, all of which apparently share a common Asiatic geographic origin. In addition, a key for identification of Longidorus found in China, based on morphological characters of both female and first-stage juvenile, is provided.

Morphological and molecular characterisation of Longidorus juglans sp. nov. and a sister species L. fangi Xu & Cheng, 1991 (Nematoda: Longidoridae) from China

Longidorus juglanssp. nov. is a new needle nematode detected from the rhizosphere of a walnut tree in Shanxi Province, P.R. China. It was distinguished by female body length of 3.9-5.2 mm; lip region 14-18 μm wide, rounded and continuous, amphidial fovea pocket-shaped without distinct basal lobes; moderately long odontostyle (125-140 μm); guide ring at mid-odontostyle and situated 69-78 μm from anterior end; short and blunt conoid tail (30-41 μm long, c = 118-147, c′ = 0.6-0.9), bearing 2-3 caudal pores on each side. The male ofL. juglanssp. nov. is 5.1 mm long, with 13 ventro-median supplements, a short and blunt conoid tail bearing 3-4 caudal pores on each side, and spicules 73 μm long. Three developmental juvenile stages were recognised. This new species is very similar to another Chinese speciesL. fangiin general morphology, but can be distinguished by the number of juvenile stages and DNA sequences of SSU, ITS1, ITS2 and D2-D3 of LSU rDNA. Morphological and molecular characterisation was provided forL. fangirepresenting two new geographical records. The phylogenetic relationships among these species were analysed using data from SSU, D2-D3 of LSU, ITS1 and ITS2 rDNA, which revealed thatL. juglanssp. nov. andL. fangiwere clustered together withL. diadecturus,L. litchiiandL. jonesiwhose guide ring is located at mid-odontostyle level.

Exploring cryptic diversity in publicly available strains of the model diatom Thalassiosira pseudonana (Bacillariophyceae)

The model diatom Thalassiosira pseudonana is believed to be a single species with a global distribution, but it has not been confirmed previously whether isolates from different environmental and geographic origins are genotypically and phenotypically identical. In the present study, a polyphasic approach was employed to characterize nine clonal isolates, plus an additional replicate of one of the isolates, of the diatom T. pseudonana from culture collections to investigate whether there was any cryptic speciation in the publicly available strains of this species. Morphological analysis using scanning electron microscopy concluded that the strains were indistinguishable. Furthermore, conventional DNA barcoding genes (SSU rDNA, ITS1 and ITS2 rDNA and rbcL), revealed no nucleotide variation among the strains tested. On employing a whole genome fingerprinting technique, Amplified Fragment Length Polymorphism (AFLP), three clusters were revealed, although the level of variation between the clusters was surprisingly low. These findings indicate a low level of diversity among these cultured T. pseudonana strains, despite their wide spatial and temporal distribution and the salinity range of their original habitats. Based on the limited number of available strains, this suggests that T. pseudonana is a highly conserved diatom that nevertheless has an ability to tolerate wide ranges of salinity and populate varied geographic locations.

Life cycles, molecular phylogeny and historical biogeography of the ‘pygmaeus’ microphallids (Digenea: Microphallidae): widespread parasites of marine and coastal birds in the Holarctic

SUMMARYThe ‘pygmaeus’ microphallids (MPG) are a closely related group of 6 digenean (Platyhelminthes: Trematoda) Microphallus species that share a derived 2-host life cycle in which metacercariae develop inside daughter sporocysts in the intermediate host (intertidal and subtidal gastropods, mostly of the genus Littorina) and are infective to marine birds (ducks, gulls and waders). Here we investigate MPG transmission patterns in coastal ecosystems and their diversification with respect to historical events, host switching and host-parasite co-evolution. Species phylogenies and phylogeographical reconstructions are estimated on the basis of 28S, ITS1 and ITS2 rDNA data and we use a combination of analyses to test the robustness and stability of the results, and the likelihood of alternative biogeographical scenarios. Results demonstrate that speciation within the MPG was not associated with co-speciation with either the first intermediate or final hosts, but rather by host-switching events coincident with glacial cycles in the Northern Hemisphere during the late Pliocene/Pleistocene. These resulted in the expansion of Pacific biota into the Arctic-North Atlantic and periodic isolation of Atlantic and Pacific populations. Thus we hypothesize that contemporary species of MPG and their host associations resulted from fragmentation of populations in regional refugia during stadials, and their subsequent range expansion from refugial centres during interstadials.

Phylogenetic Analysis of the Lichen Family Umbilicariaceae based on nuclear ITS1 and ITS2 rDNA Sequences

The lichen family Umbilicariaceae is accepted by most lichenologists as consisting of two genera, Lasallia and Umbilicaria. The monophyly of these two genera was examined by phylogenetic analyses of nucleotide sequences of ITS 1 and ITS2 rDNA. Sequences of these regions from three Lasallia and 17 Umbilicaria species were aligned to those of seven representatives of the outgroup taxa including Eurotiales, Onygenales and Caliciales (Mycocaliciaceae) and subjected to maximum parsimony, maximum likelihood and neighbour-joining analyses. The resulting phylogenetic hypotheses supported the monophyly of the representative species of Lasallia. However, the species of Umbilicaria did not form a monophyletic sistergroup to Lasallia due to the basal placement of other Umbilicaria species in some analyses. Based on these analyses, if Lasallia is recognized as a separate genus then Umbilicaria appears to be paraphyletic. Although further taxon sampling is required to resolve the monophyly of Umbilicaria, for the present we recommend retaining the current treatment of Lasallia as separate from Umbilicaria.