Multiple lineages and absence of panmixia in the “circumpolar” crinoid Promachocrinus kerguelensis from the Atlantic sector of Antarctica

Nuclear and Mitochondrial Gene Data Support Recent Radiation within the Sea Spider Species Complex Pallenopsis patagonica

“…These also showed mostly circum-Antarctic distribution instead of regional partitioning. Similar findings were made for the crinoid Promachocrinus kerguelensis [Wilson et al (2007): restricted distribution range; Hemery et al (2012): circumpolar distribution range with extended data set]. Interestingly, analyses of a nuclear gene of C. megalonyx indicated that several of the mitochondrial clades do not represent distinct species as they had identical sequences for the otherwise highly variable nuclear internal transcribed spacer region (ITS; Dietz et al, 2015b).…”

Cryptic mitochondrial lineages in the widespread pycnogonid Colossendeis megalonyx Hoek, 1881 from Antarctic and Subantarctic waters

“…Of these 264 species, 233 (88.3%) are endemic to Antarctic and/or Subantarctic waters (Munilla and Soler Membrives 2008). In the last decade, several molecular genetic studies in the marine Antarctic benthos provided strong evidence that Antarctic biodiversity is severely underestimated due to the presence of multiple morphologically highly similar lineages that most likely represent cryptic species (Allcock et al 1997;Held 2003;Held and Wägele 2005;Hunter and Halanych 2008;Leese and Held 2008;Linse et al 2007; Raupach and Wägele 2006;Raupach et al 2007;Thornhill et al 2008;Wilson et al 2007, Wilson et al 2009). A first study on the population structure of Nymphon australe, an Antarctic pycnogonid, for which a circumpolar distribution is assumed, revealed that several cryptic lineages co-occur in this taxon, which are likely to represent cryptic species .…”

Brooding and Species Diversity in the Southern Ocean: Selection for Brooders or Speciation within Brooding Clades?

“…In addition, because most of the glacial cycles occurred during the Pliocene and Pleistocene over only the past few million years, genetic divergence of these fragmented populations would be relatively slight, and very similar or cryptic sister species would be predicted. Molecular analyses have revealed cryptic species in isopods, which brood (Held, 2003;Held and Wägele, 2005), and a bivalve that broods as well as in a crinoid, which has pelagic, lecithotrophic larvae (Wilson et al, 2007). Pearse and Bosch (1994) analyzed available data for mode of development in shallow-water Antarctic and subantarctic echinoderms (128 species) and found the highest proportion of species with nonpelagic development in the region of the Scotia Arc (65%), not the Antarctic continent or subantarctic islands (42% each).…”

“…However, phylogenetic analyses of Promachocrinus kerguelensis in the Atlantic section of the Southern Ocean revealed at least fi ve "species-level" clades (Wilson et al, 2007). P. kerguelensis is found throughout Antarctic and subantarctic waters, and the one population studied, in McMurdo Sound, produces large numbers of pelagic, lecithotrophic larvae (McClintock and Pearse, 1987).…”