Notes on important algal herbaria,V

The seasonal succession of algal species in the epipelon of two small pools over a period of three years is described in relation to changes in silica, nitrate-nitrogen and phosphate-phosphorus concentrations in the water above the sediments. Recurring patterns of seasonal growth of the various species are discussed.     

A synopsis of the genusScleromitrula (=Verpatinia) (Ascomycotina: Helotiales: Sclerotiniaceae)

The systematics ofScleromitrula andVerpatinia of the family Sclerotiniaceae is reevaluated on the basis of morphological, cultural and molecular criteria.Scleromitrula shiraiana, Verpatinia species andCiborinia candolleana share gross morphological, microanatomical and cultural features which clearly distinguish them from the closely relatedCiborinia andRutstroemia species. Phylogenetic analyses of sequences from the internal transcribed spacer region (ITS1, ITS2, and the 5.8S gene) of nuclear ribosomal DNA demonstrate that the stipitate-capitate specimens ofScleromitrula andVerpatinia species plus the stipitate-cupulateCiborinia candolleana constitute a monophyletic clade separate from a clade including the type species ofCiborinia. Scleromitrula is emended to includeS. shiraiana, the new speciesS. rubicola, C. candolleana, and specimens formerly assigned toVerpatinia. A key to the accepted species ofScleromitrula is provided.     

Description of Hemicaloosia graminis n. sp. (Nematoda: Caloosiidae) Associated with Turfgrasses in North and South Carolina,USA

A new nematode species was discovered during a diversity survey of plant-parasitic nematodes on turfgrass conducted in North and South Carolina in 2010 and 2011. It is described herein as Hemicaloosia graminis n. sp. and is characterized by two annuli in the lip region, one lateral line, body 610.0–805.0 μm long, stylet 65.0–74.6 μm long, vulva at 84.1% –85.8% of the body , 254–283 annuli, vulva at the 38–53^rd annulus from tail terminus, 12–14 annuli between vulva and anus, tail elongate-pointed, 67.5–84.8 μm long in females and spicule straight, 31.0 μm long, caudal alae well developed, two lateral lines in males. The newly described species is morphologically closest to H. paradoxa, but has a longer stylet (65.0–74.6 vs 61.0–65.0 μm) and a higher V-value (84.1–85.8 vs 78.1–84.0%), less RV (38–53 vs 50–56), higher RVan (12–14 vs 10) in females, and a shorter tail (30.1 vs 36.7 μm) and more anteriorly located excretory pore (105.9 vs 140.0 μm) in the male. It was easily differentiated from other species based on near-full-length small subunit rRNA gene (SSU) and ITS1 sequences. Phylogenetic analysis from SSU supports placement in a monophyletic clade with the genus Caloosia. An identification key and a table of distinguishing characteristics are presented for all seven species of Hemicaloosia.     

Phylogeography of the Rhabditis (Pellioditis) marina species complex: evidence for long-distance dispersal, and for range expansions and restricted gene flow in the northeast Atlantic

Pinpointing processes that structure the geographical distribution of genetic diversity of marine species and lead to speciation is challenging because of the lack of obvious dispersal barriers and the likelihood of substantial (passive) dispersal in oceans. In addition, cryptic radiations with sympatric distributions abound in marine species, challenging the allopatric speciation mechanism. Here, we present a phylogeographical study of the marine nematode species complex Rhabditis ( Pellioditis ) marina to investigate processes shaping genetic structure and speciation. Rhabditis ( P .) marina lives on decaying macroalgae in the intertidal, and may therefore disperse over considerable distances. Rhabditis ( P .) marina consists of several cryptic species sympatrically distributed at a local scale. Genetic variation in the COI gene was screened in 1362 specimens from 45 locations around the world. Two nuclear DNA genes (ITS and D2D3) were sequenced to infer phylogenetic species. We found evidence for ten sympatrically distributed cryptic species, seven of which show a strong genetic structuring. A historical signature showed evidence for restricted gene flow with occasional long-distance dispersal and range expansions pre-dating the last glacial maximum. Our data also point to a genetic break around the British Isles and a contact zone in the Southern Bight of the North Sea. We provide evidence for the transoceanic distribution of at least one cryptic species (PmIII) and discuss the dispersal capacity of marine nematodes. The allopatric distribution of some intraspecific phylogroups and of closely related cryptic species points to the potential for allopatric speciation in R. ( P .) marina .