Namanereidinae

Namanereidinae is a subfamily of nereidid polychaete worms which are adapted to live in habitats of low salinity, unlike most other polychaetes which inhabit marine environments. According to the World Register of Marine Species, there are 50 valid species in two genera; a third genus, Lycastoides is a taxon inquirendum due to the loss of its type specimen. They are found from the tropics to high latitudes, and inhabit intertidal areas to "uplifted coastal areas"; a number of species are hypogean stygobionts, inhabiting groundwater and exhibiting the typical features of cave animals, such as skin depigmentation and eyelessness. Various species are known to associate with plants and plant debris, and they seem to prefer these habitats.

Taxonomy

The scientific names of both genera combine the Ancient Greek word nama-, meaning spring or stream, with Lycastis and Nereis, being two scientific names used for nereidid worms. Both generic names thus allude to the freshwater habitats that are inhabited by some species in the subfamily. Namalycastis species tend to be larger-bodied than those of Namanereis, possesses four pairs of tentacular cirri, short and subconical antennae, along with "flattened and leaf-like posterior cirrophores". In contrast, Namanereis is smaller, has three pairs of tentacular cirri, no dorsal cirrophores nor notosetae, and a "tripartite pygidium. Features of the setae and their rows/bundles (fascicles) are essential in identifying both genus and species ==Description==

Description

Members of Namanereidinae are diagnosed through the presence of paired lateral antennae (though some species lack these), the larynx being divided into oral and maxillary rings though lacking paragnaths or papillae, biarticulated palps with compact palpophores, 3-4 pairs of cirri on the tentacles, along with the "parapodia reduced to sesquiramous with notopodia reduced, lacking notopodial lobe or ligules and showing only dorsal cirri and notoaciculae; notochaetae as sesquigomph spinigers; neurochaetae including sesquigomph spinigers, heterogomph falcigers and heterogomph spinigers in supra-acicular fascicles; heterogomph spinigers, heterogomph pseudospinigers and heterogomph falcigers in sub-acicular fascicles". In all members of the subfamily, the distal region of the palp, the palpostyle, is spherical in shape, and the notoacicula are placed ventrally. ==Distribution==

Distribution

The modern, widespread distribution of Namanereis may suggest vicariance from the breakup of Gondwana in the Late Jurassic. Alternatively, it may indicate speciation from marine Namanereis ancestors which independently colonized inland environments. Plesiomorphic features in the marine species seems to support the latter theory; that being the ancestral namanereidine inhabited coastal, euryhaline habitats. Socotra, and Australia. Namalycastis hawaiiensis is known to be introduced to countries outside its native habitat; with a broad natural distribution in the Indo-Pacific from Sumatra to Hawaii, and from the Ryukyus to Papua New Guinea, Conversely, the temperate species inhabit the North Island, along with subantarctic locales such as the Strait of Magellan, Auckland Island, Adams Island, and Campbell Island. ==Habitat==

Habitat

Across the species, namanereidines can tolerate salinities from fresh/potable water to hypersaline conditions of 13% salinity. and several species associate with the Nypa palm. Still some other species inhabit the leaf litter of mangrove forests, a "semiterrestrial" environment. A number of species are seemingly highly resistant to the effects of pollutants, such as industrial waste, organics, hydrocarbons, and heavy metals. ==References==

Source: Wikipedia ↗

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