Thursday 8 August 2013

Four new species of Bryozoans from New Zealand.

Bryozoans, or Moss Animals, are colonial filter-feeding invertebrates that form encrusting or weed-like colonies. The individual 'animals' are on average about 0.5 mm in length, and live inside a protective covering from which they extend a crown of cilia-covered tentacles called a lophophore. These are not true individuals though as they develop as buds on the colony and share nutrients; for this reason they are referred to as 'zooids'. The colonies produce sexually by means of reproductive zooids that have gonads, but lack feeding apparatus. Bryozoans are widespread globally, but are often overlooked because they are small and the colonies resemble plants.

In a paper published in the journal Zootaxa on 8 May 2013, Dennis Gordon of the National Institute of Water & Atmospheric Research in Wellington, New Zealand and Mary Spencer-Jones of the The Natural History Museum in London, describe four new species of Bryozoans from New Zealand.

All of the new species are placed in the genus Amanthia, branching tree-like Bryozoans with individual zooids arranged in slightly offset pairs along the branches, and were discovered during a review of the genus in New Zealand.

The first new species is named Amathia gracei, in honour of Roger Grace, a well known New Zealand research diver and environmentalist. The species is described from a single colony found living between 56 and 58 m off the northeast coast of East Cape on North Island. Amathia gracei forms erect branching colonies up to 70 mm high, with a stout tuft of anchoring rhizoids (rootlike structures used to anchor it to the substrate).

Colony of Amathia gracei. Gordon & Spencer-Jones (2013).

Detail of part of the colony, showing zigzagged clusters of autozooids. Gordon & Spencer-Jones (2013).

The approximate location of the site where Amathia gracei was discovered. Google Maps.

The second new species described is named Amathia similis, where 'similis' means 'alike' or 'similar to', due to its close resemblance to a Brazilian species, Amathia distans. While it is possible to distinguish the two species, Gordon & Spencer-Jones suggest that the close resemblance, combined with the fact that Amathia similis was discovered living at Opua Marina in the Bay of Islands, suggests the species may not be native to New Zealand. The species forms erect, densely branching colonies up to 87 mm high, the branches splitting in two roughly every 3 mm. 

Colony of Amathia similis. Gordon & Spencer-Jones (2013).

Close up of Amathia similis, showing clusters of zooids on branches. Gordon & Spencer-Jones (2013).

The location of Opua Marina, where Amathia similis was discovered. Google Maps.

The third new species is named Amathia chimonidesi, in honour of Pantelakis Chimonides of the natural History Museum in London, who has contributed to the study of Bryozoans of the genus Amanthia. The species was found forming large colonies in Waitemata Harbour, Auckland, leading Gordon & Spencer-Jones to suggest that this to is an invasive species, since it is only known from within a harbour, and appears to have been present there for less than a decade. Amathia chimonidesi forms erect, densely branching colonies up to 168 mm high.

Colony of Amathia chimonidesiGordon & Spencer-Jones (2013).

Close up of Amathia chimonidesi, showing clusters of zooids. Gordon & Spencer-Jones (2013).

The location of Waitemata Harbour, where Amathia chimonidesi was discovered. Google Maps.

The final new species described is named Amathia zealandica, a name that refers to the country where it was found, and to which it is presumed to be endemic (native). Amathia zealandica was found growing over a large area to the northeast of Spirits Bay, on the northern tip of North Island. The species forms erect, densely branching colonies up to 66 mm high.

Colony of Amathia zealandicaGordon & Spencer-Jones (2013).

Detail of Amathia zealandica, showing individual zooids. Gordon & Spencer-Jones (2013).

The approximate area where Amathia Zealandica was discovered. Google Maps.

See also A new species of Bryozoan from the Atlantic coast of Iberia and New species of Bryozoans from Brazil.

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