A new spionid polychaete, Prionospio expansa sp. nov., collected from the intertidal habitat of the Yellow Sea in Korea, is described. The new species is closely related to P. japonica Okuda, 1935 from Northeast Asia both morphologically and genetically. They share four pairs of branchiae which are cirriform and apinnate, whereas the new species differs from P. japonica in the length of the branchiae, expansion of the anteriormost body, and size of the first notopodial postchaetal lamellae. Herein, a detailed description and illustrations of P. expansa sp. nov. are provided, with molecular data for three gene fragments: mitochondrial cytochrome c oxidase subunit I, 16S ribosomal DNA (rDNA), and nuclear 18S rDNA. A phylogenetic analysis was conducted based on mitochondrial and nuclear gene fragments.
Two new spionid polychaetes of the genus Scolelepis from the intertidal habitats of the Yellow Sea in Korea are described and illustrated. Scolelepis (Parascolelepis) anterobranchiata sp. nov. is characterized by a combination of the following characteristic: palps with smooth globular expansions at the basal part, branchiae appearing in the anterior part of the body, absence of notochaetae in chaetiger 1, notopodial postchaetal lamellae partially fused with branchiae in anterior chaetigers, and neuropodial hooded hooks appearing from chaetigers 18–19 with two pairs of teeth surmounting a well-developed main fang. Scolelepis (Scolelepis) rubra sp. nov. can be distinguished from its congeners by the following characteristics: reddish-pink body, presence of notochaetae in chaetiger 1, branchiae approximately twice as long as notopodial postchaetal lamellae, neuropodial bidentate hooded hooks usually appearing from chaetigers 26–31, and presence of notopodial hooded hooks in posterior chaetigers. Based on molecular data, the sequences of the two new species showed relatively large genetic distances from other Scolelepis species in COI (15.8–19.5%) and 16S rDNA (4.9–15.8%). Morphological variability of prostomial shape in the genus Scolelepis is discussed for the first time.
A new spionid polychaete, Rhynchospio aciliatasp. nov., was discovered in the fine sandy sediments of an intertidal habitat from Korean waters. The new species is considered a simultaneous hermaphrodite, but no brooding embryos were found in any of the specimens collected in this study. This species is unique in the absence of ciliation in the anteriormost chaetigers. Rhynchospio aciliatasp. nov. is morphologically most similar to Rhynchospio foliosa Imajima, 1991 from Japan in having an elevation on the prostomium, conspicuously large and foliaceous branchiae, and intersegmental lateral pouches. However, the new species differs from the latter by the following characteristics: (1) large and lanceolate notopodial postchaetal lamellae of chaetiger 1, (2) transverse ciliated bands and ciliation on the inner branchiae absent in anteriormost chaetigers, and (3) pygidium with one pair of ventral cirri and numerous elongated dorsolateral cirri. Detailed description and illustrations of the new species are provided with molecular information on mitochondrial cytochrome c oxidase subunit I (COI), 16S ribosomal DNA (rDNA), nuclear 18S rDNA, and 28S rDNA.
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