Nereis acuminata Ehlers 1868: 552.
Neanthes caudata. Hartman 1959: 250; Ben-Eliahu 1991: 322; Amoureux et al. 1980: 388. Nereis caudata. Ben-Eliahu 1972: 220.
Material examined. Iran, Persian Gulf, Abu Musa Island, southern part of the Quay, one specimen (ZUTC Ann. 61 52).
Description. Material examined here is incomplete with 40 chaetigers. Paragnaths on maxillary ring arranged as follows: I = 17, II = a crescent group of about 30, III = a cluster in three transverse rows, IV = cluster of small paragnaths. Paragnaths on oral ring arranged as follows: V-VI -VII–VIII = a continuous broad transverse band of many paragnaths with large cones in area V. Anterior notopodia have three triangular ligules (i.e. prechaetal notopodial lobe present), dorsal cirrus shorter than dorsal ligule. Anterior neuropodia have two ligules (acicular and ventral ligules) and digitate postchaetal lobe. Ventral cirrus shorter than ventral neuropodial ligule. Median notopodia similar to anterior notopodia, however dorsal cirrus relatively longer. Neurochaetae all homogomph spinigers and heterogomph falcigers. Falcigers have long, serrated blades with blunt tips.
Remarks. According to Reish et al. (2014) the Neanthes acuminata (Ehlers, 1868) species complex is cosmopolitan in distribution and comprises at least four morphologically identical species: N. acuminata, N. arenaceodentata Moore, 1903, N. caudata (delle Chiaje, 1841) and N. cricognatha (Ehlers, 1904). Members of the species complex can only be distinguished by chromosome number, eye and egg colouration and molecular data. All previous references to the species complex in the region refer to N. caudata; however, this name is currently invalid as it was based on a misapplication of Lamarck's nomination of a spionid species, Spio caudatus (Read & Bellan 2016). This is the first record of Neanthes acuminata species complex from the Persian Gulf.
Distribution. Suez Canal, Red Sea (Wehe & Fiege 2002). Mediterranean Sea, Indian Ocean (Fauvel 1950), The Philippines, Japan, Southern California, New Zealand, Australia (Reish et al. 2014).