Meridiastra

Meridiastra is a genus of starfish in the family Asterinidae.^[2][3] The genus is found in the Indian and Pacific Oceans,^[4] with most records from the waters around Australia.^[3] They occur in shallow waters down to a depth of about 59 m (194 ft). Meridiastra are morphologically similar to the Atlantic genus Asterina. They are also phylogenetically close and possibly sister genera.^[4]

Meridiastra
Meridiastra atyphoida – the type species
Scientific classification
Kingdom:	Animalia
Phylum:	Echinodermata
Class:	Asteroidea
Order:	Valvatida
Family:	Asterinidae
Genus:	Meridiastra O'Loughlin, 2002[1]
Type species
Asterina atyphoida H.L. Clark, 1916
Species
11 species (see text)

Etymology

The generic name is derived from the Latin meridies (=south) and astrum (=star), in reference to the southern Australian and Pacific distribution of the genus^[1] (at the time of description – the genus now includes also species occurring on the northern hemisphere (Mexico, Panama)^[4]).

Meridiastra calcar – an example of a species with distinct rays

Meridiastra medius – an example of a species with indistinct rays

Description

Meridiastra are sea stars with five to eight rays (arms). They range from very small (Meridiastra rapa: radius 6 mm (0.24 in)) to medium-sized (Meridiastra gunnii: radius 56 mm (2.2 in)). The interradial margin is straight to incurved; when the rays are distinct, they have narrowly rounded to pointed tips.^[4] One species, Meridiastra fissura, is fissiparous.^[1][4]

Species

There are 11 recognized species:^[2]

• Meridiastra atyphoida (H.L. Clark, 1916)
• Meridiastra calcar (Lamarck, 1816)
• Meridiastra fissura O'Loughlin, 2002
• Meridiastra gunnii (Gray, 1840)
• Meridiastra medius (O'Loughlin, Waters & Roy, 2003)
• Meridiastra modesta (Verrill, 1867)
• Meridiastra mortenseni (O'Loughlin, Waters & Roy, 2002)
• Meridiastra nigranota O'Loughlin, 2002
• Meridiastra occidens (O'Loughlin, Waters & Roy, 2003)
• Meridiastra oriens (O'Loughlin, Waters & Roy, 2003)
• Meridiastra rapa O'Loughlin, 2002