Patiriella mortenseni is a sea star

Sea star

Starfish or sea stars are echinoderms belonging to the class Asteroidea. The names "starfish" and "sea star" essentially refer to members of the class Asteroidea...

 of the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Asterinidae

Asterinidae

Asterinidae is a large family of sea stars in the order Valvatida. It contains twenty-five genera.-Genera:*Ailsastra O'Loughlin & Rowe, 2005*Allopatiria Verrill, 1913*Anseropoda Nardo, 1834...

 endemic to New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

. Discovered as a new species in 2002, it is named after T. Mortensen, who recorded it as distinct from Patiriella regularis

Patiriella regularis

Patiriella regularis, or New Zealand common cushion star, is a sea star of the family Asterinidae, endemic to New Zealand. It has an armspread of up to 60 mm.-Research:...

, the New Zealand common cushion star, in 1925.

Reciprocal transplant experiment

Transplant experiment

Transplant experiment known as a common garden experiment, is an experiment where one or more organisms are moved from one environment to another environment. In a usual common garden experiment, two species of plants growing in their native environments would both be transplanted in a common...

s in Fiordland

Fiordland

Fiordland is a geographic region of New Zealand that is situated on the south-western corner of the South Island, comprising the western-most third of Southland. Most of Fiordland is dominated by the steep sides of the snow-capped Southern Alps, deep lakes and its ocean-flooded, steep western valleys...

 have shown it is less tolerant of hyposaline

Salinity

Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...

 conditions than close relative Patiriella regularis

Patiriella regularis

Patiriella regularis, or New Zealand common cushion star, is a sea star of the family Asterinidae, endemic to New Zealand. It has an armspread of up to 60 mm.-Research:...

. This is reflected in its distribution: it lives in deeper waters (at depths of roughly 10±3 m in Milford

Milford Sound

Milford Sound is a fjord in the south west of New Zealand's South Island, within Fiordland National Park, Piopiotahi Marine Reserve, and the Te Wahipounamu World Heritage site...

 and Doubtful Sound

Doubtful Sound

Doubtful Sound is a very large and naturally imposing fjord in Fiordland, in the far south west of New Zealand. It is located in the same region as the smaller but more famous and accessible Milford Sound...

s), below the low salinity layer (LSL). In laboratory

Laboratory

A laboratory is a facility that provides controlled conditions in which scientific research, experiments, and measurement may be performed. The title of laboratory is also used for certain other facilities where the processes or equipment used are similar to those in scientific laboratories...

 conditions they die after 24 hour exposure to water with salinities below 25‰.