Abstract
Two new species of benthopelagic copepods of the genus Stephos T. Scott, 1892, belonging to the family Stephidae G.O. Sars, 1902, are described based on specimens collected in the stagnant water flooding the burrows excavated by ocypodid crabs in two intertidal mud-flats, and from near-bottom shallow waters in Korea, respectively. They can be easily diagnosed based on the ornamentation of both the female genital double-somite and genital operculum; the morphology of the distal segment of the male right P5; the presence/absence of a tiny pointed process on the distomedial angle of second segment of female P5; and the condition (seta or spine) of the lateral armature element on the distal segment of female fifth legs, among other features. This is one of the few cases reported of calanoid copepods living as commensals of other invertebrates, and raises to six the number of members of the genus reported from Asia. This is also the first record of the family Stephidae in Korea.
Highlights
The genus Stephos shows many similarities in its morphological characteristics with its congener genera Miostephos, Parastephos, and Speleohvarella; well, differs in the following characteristics: (1) the basal exite of the maxillule is present in Stephos and Miostephos, (2) the right P5 is 4-segmented in Stephos; and (3) male right P5 is ending in unarmed claw and/or mitten-like segment (Boxshall and Halsey 2004; Kršinić 2005)
As an update we report that Stephos has 30 nominal species including the two described : S. angulatus, S. antarcticum Wolfenden, 1908, S. articus G.O
Six species of Stephos have so far been reported in Asian waters in particular East Asia: S. pentacanthos from China (Chen and Zhang 1965), S. pacificus, S. robustus, and S. tsuyazakiensis from Japan (Tanaka 1966; Ohtsuka and Hiromi 1987), and S. geojinensis sp. n. and S. projectus sp. n. from Korea
Summary
The genus Stephos is the largest and more primitive, currently comprising 28 valid species found in anchialine and marine coastal near-bottom habitats from tropical to polar regions (Ohtsuka and Hiromi 1987; Bradford-Grieve 1999; Zagami et al 2000; Boxshall and Halsey 2004; Jaume et al 2008; Kršinić 2012). Most of them have so far been recorded from the North Atlantic and adjacent waters (Boxshall and Halsey 2004; Jaume et al 2008; Kršinić 2012), and from the Indo-Pacific region (Mori 1942; Chen and Zhang 1965; Andronov 1974; Bradford-Grieve 1999; Ohtsuka and Hiromi 1987)
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