Redescription of the Tintinnid Stenosemella pacifica Kofoid and Campbell, 1929 (Ciliophora, Spirotricha) Based on Live Observation, Protargol Impregnation, and Scanning Electron Microscopy

Abstract

The tintinnid ciliate Stenosemella pacifica Kofoid and Campbell, 1929 was occasionally recorded from the pelagial of temperate, subtropical, and tropical neritic waters. Since its cytological features were unknown, the species is redescribed from material collected in the pelagial of the Irish Sea, using live observation, protargol impregnation, and scanning electron microscopy. Furthermore, the species diagnosis is improved to include new characteristics, e.g. the somatic ciliary pattern comprising a ventral, dorsal, and posterior kinety as well as a right, left, and lateral ciliary field. The stomatogenesis of S. pacifica is typical for species with such a complex somatic ciliary pattern: the oral primordium develops hypoapokinetally posterior to the lateral ciliary field. The presence of windows in the lorica collar of Stenosemella ventricosa, the type of the genus, necessitates (i) an improved genus diagnosis, (ii) a synonymization of the genus Luminella Kofoid and Campbell, 1939, and (iii) a transfer of the Luminella species to the genus Stenosemella, including Luminella neocalifornica, which becomes Stenosemella neocalifornica nov. comb. Owing to the lack of a description, Stenosemella crateri is considered a nomen nudum. KeywordsBiogeography; ciliary pattern; morphology; ontogenesis; taxonomy; Tintinnina; ultrastructure THE classification of the about 1,200 tintinnid choreotrichid species is merely based on lorica morphology, as cytological features, including the ciliary pattern, are only known in 17 species (Agatha and Riedel-Lorjé 2006;Blatterer and Foissner 1990;Cai et al. 2006;Choi et al. 1992;Foissner, Berger, and Schaumburg 1999;Foissner and O'Donoghue 1990;Foissner and Wilbert 1979;Petz, Song, and Wilbert 1995;Sniezek et al. 1991;Snyder and Brownlee 1991;Song and Wilbert 1989;Wasik and Mikozajczyk 1994). Since tintinnid loricae are polymorphic due to environmental factors and the life cycle (Bakker and Phaff 1976;Bernatzky, Foissner, and Schubert 1981;Biernacka 1965;Davis 1978Davis , 1981Gold and Morales 1975b;Laval-Peuto 1981;Laval-Peuto and Brownlee 1986), the reconstruction of the phylogenetic relationships and hence the establishment of a natural classification require MATERIALS AND METHODS CollectionSamples were taken with a 20-μm plankton net from the upper 50 cm of the Irish Sea in front of the Port Erin Marine Laboratory (University of Liverpool) on the Isle of Man in May 2002 at a salinity of about 35‰ and a temperature of about 12 °C. Taxonomic studiesCell movement was studied in a Petri dish (about 6 cm across; water depth about 2.5 cm) under a dissecting microscope at about 20 °C. Cell morphology was investigated under a compound microscope equipped with a high-power oil immersion objective as well as bright-field and interference contrast optics. Protargol impregnation followed the protocol of Song and Wilbert (1995). For scanning electron microscopy, cells were fixed for 30 min in a modified Parducz' solution made of six parts of 2% osmium tetroxide (OsO 4 , w/v) in artifi...

A survey of ciliates at the long-term sampling station “Helgoland Roads”, North Sea

“…pacifica is a widely distributed tintinnid, which has been recorded in the North Atlantic (Agatha and Tsai 2008), the Gulf of Mexico (Balech 1968), the Yellow Sea (Xu and Song 2005), the North Pacific Campbell 1929, 1939) and the South Pacific (Burns 1983). According to our observations, its lorica was about 40-60 lm long and was composed of an agglomerated bowl and a short unobvious hyaline collar that sometimes was covered by an agglomerated second collar (as described in Agatha and Tsai 2008). It often occurred from late autumn until early spring at Helgoland Roads with an abundance normally varying between 20 and 150 cells L -1 .…”

Redescriptions of three tintinnid ciliates, Tintinnopsis tocantinensis, T. radix, and T. cylindrica (Ciliophora, Spirotrichea), from coastal waters off China

“…(Laval-Peuto 1994), Stenosemella pacifica (Agatha and Tsai 2008), Tintinnopsis cylindrica (Agatha and Riedel-Lorjé 2006), T. fimbriata (Agatha 2008), and T. parvula (Agatha 2010a). Tintinnopsis tocantinensis is consistent with all these in that the oral primordium is located posterior to the lateral ciliary field.…”

Biodiversity of oligotrich ciliates in the South China Sea: description of three newStrombidiumspecies (Protozoa, Ciliophora, Oligotrichia) with phylogenetic analyses

“…Of these only about half have been described using currently accepted techniques (e.g. Agatha, 2014;Agatha & Riedel-Lorj e, 1997;Lei, Xu, & Song, 1999;Martin & Montagnes, 1993;Montagnes, Lynn, Stoecker, & Small, 1988;Montagnes, Taylor, & Lynn, 1990;Petz, Song, & Wilbert, 1995;Song, Wang, & Warren, 2000). During the past decade, eight new Strombidium species have been reported, which indicates that there is still much to learn about the diversity of this genus (Agatha, Str€ uder-Kypke, Beran, & Lynn, 2005;McManus, Xu, Costas, & Katz, 2010;Song, 2005;Song et al, 2015;Wilbert & Song, 2005;Xu, Sun, Song, & Warren, 2008;Xu, Warren, & Song, 2009).…”