Two New Species of the Genus Longipedia Claus, 1863 (Copepoda: Harpacticoida: Longipediidae) from Korea, with an Update and a Key to Species

Abstract

Benthic harpacticoids were collected from Korean waters. Two species were identified as members of the genus Longipedia Claus, 1863, because they have an extremely elongated distal segment of the P2 endopod. Longipedia koreana sp. nov. is morphologically most closely related to L. nichollsi Wells, 1980 and L. scotti Sars, 1903, but it can clearly be distinguished from both species based on the following morphological characteristics: P1 coxa with strong spinules near the outer margin and the distal element being much bigger than the proximal elements, P2 coxa with a small inner seta on the anterior surface, P4 exopod first segment without an inner element, and the P5 with a rectangular exopod (more than 3.5 times as long as wide). L. ulleungensis sp. nov. is similar to L. brevispinosa Gurney, 1927, L. spinulosa Itô, 1981, and L. weberi Scott A., 1909. However, L. ulleungensis sp. nov. is characterized by the P2 coxa with a reduced inner seta, the P4 exopod second segment without an inner seta, and the anal operculum with a long median projection, a single spine, and a group of outer spines on each side. In a molecular analysis using the mitochondrial cytochrome c oxidase subunit I (COI) and 18S ribosomal RNA (18S rRNA) genes, the inter-specific variation was 22.525–23.102% and 1.325–1.382% of COI and 18S rRNA between the two new species, respectively. A key to the family Longipediidae is provided herein.

Comment on Bang et al. Two New Species of the Genus Longipedia Claus, 1863 (Copepoda: Harpacticoida: Longipediidae) from Korea, with an Update and a Key to Species. Diversity 2021, 13, 590

“…The opinion of Bang et al [1] to relegate Longipedia gonzalezi to a junior subjective of L. americana is not supported by the available data. We neither know if the Longipedia specimens that Onbé [3] collected were L. americana nor do we have access to these specimens for examination.…”

“…In the recent description of two new Longipedia species from Korea [1], the authors suggested that Longipedia gonzalezi Schizas et al, 2015 [2], described from Puerto Rico, northeast Caribbean Sea, should be relegated to a junior subjective synonym of L. americana Wells, 1980. This view is based on Onbé's work [3], where the naupliar and copepodid stages of L. americana are described [1].…”

“…In the recent description of two new Longipedia species from Korea [1], the authors suggested that Longipedia gonzalezi Schizas et al, 2015 [2], described from Puerto Rico, northeast Caribbean Sea, should be relegated to a junior subjective synonym of L. americana Wells, 1980. This view is based on Onbé's work [3], where the naupliar and copepodid stages of L. americana are described [1]. The publication by Onbé [3] is not a redescription of the species, but rather a description of the development series of what he considered as L. americana from Massachusetts, northeast U.S.A.…”

“…An additional character to differentiate these two species, stated in Table 3 in [2], is the ornamentation of P2 coxa with proximal row of long spinules in L. americana and no proximal row in L. gonzalezi. Other notable differences between L. gonzalezi and L. americana are: (1) The male of L. gonzalezi with three lateral spinules in the telson, but only two in L. americana; (2) Both sexes of L. gonzalezi with a smooth body, but L. americana with dorsal and ventral urosomal spinules; and (3) P6 fused to the urosome in L. gonzalezi, but both P6 swimming legs separated in L. americana.…”

“…Schizas et al [2] stated that the genus Longipedia is an ideal taxon to include genetic information together with highquality morphological observations from any new species or collections to independently decipher the number of species present. Bang et al [1] demonstrated instructively the use of molecular data to differentiate two new species from Korea, L. koreana, Bang et al, 2021 and L. ulleungensis, Bang et al, 2021. Similarly, genetic comparisons between L. americana and L. gonzalezi could establish the amount of DNA divergence between these taxa.…”