Two new species of amphipods (Crustacea: Amphipoda: Photidae) from Korean waters with a redescription of Gammaropsis longipropodi

Abstract

Three amphipods of the family Photidae collected from Korean waters are reported here with detailed descriptions and illustrations. The Korean materials of Gammaropsis examined in this study are readily assigned to G. longipropodi by the characteristic shape of gnathopod 2 in males: not slenderly produced posterior margin of the carpus, uniform width of very elongate propodus, and the transverse palm. Among the species of genus Photis, P. fischmanni is only one species bearing stridulation ridges of the basis on gnathopod 2 and coxa 3 simultaneously in females, until now. However, Photis stridulus sp. nov. also show this characteristic but is clearly distinguishable from P. fischmanni by the weak setation of the appendages, smaller eye on the anterior cephalic lobe, and the slender carpus and propodus on gnathopod 1. The genus Podoceropsis is recorded from Korean waters for the first time with the discovery of P. clavapes sp. nov. This new species is characterized by its elongate propodus and dactylus on gnathopod 2 and the shape of the posterior lobe of the basis on pereopod 5 in mature males.

Taxonomic study on the photid amphipods (Senticaudata, Corophiida, Photoidea, Photidae) from Korean waters, with descriptions of a new genus and seven new species

“…Podoceropsis clavapes Jung, Choi, Kim & Yoon, 2017, which is the only known Podoceropsis species from Korean waters, is characterized by its peculiarly shaped gnathopod 2 in mature males: the propodus is markedly stout and enlarged (1.4 times as long as basis), the palmar margin has one proximal cavity and two distal protrusions, and the dactylus is stout and 0.8 times as long as the propodus (Jung et al 2017). Podoceropsis pseudoclavapes sp.…”

“…Podoceropsis pseudoclavapes sp. nov. has a similar shape of gnathopod 2 propodus in males to that of P. clavapes , but notably differs by gnathopod 1 propodus, which is half as long as the carpus (0.8 times as long as carpus in P. clavapes ), the palmar margin of gnathopod 2, which has one rectangular protrusion and one distal cavity (one proximal cavity and two distal protrusions in P. clavapes ), gnathopod 2 dactylus, which is 0.4 times as long as the propodus (0.8 times as long as propodus in P. clavapes ), the merus of pereopods 3 and 4, which are half as wide as long (0.4 times as wide as long in P. clavapes ), the posterior margin of pereopod 5 basis, which has an additional lobe, but it is not produced distally (also with lobes but differently produced distally in P. clavapes ), and both rami of uropod 3, which are subequal in length and 0.9 times as long as the peduncle (inner ramus is 0.9 times as long as outer ramus and 0.7 times as long as peduncle in P. clavapes ) (Jung et al 2017).…”

“…The superfamily Photoidea is positioned under the parvorder Caprellidira. To date, the Photidae, under the Senticaudata, consists of 17 genera including more than 220 nominate species distributed worldwide (Jung et al 2017).…”

“…In the Far East, the taxonomic studies on the Photidae have been carried out by Bulytscheva (1952), Gurjanova (1938, 1951, 1955), Hirayama (1984), Kudryashov and Tzvetkova (1975), Nagata (1961, 1965), and Ren (1992, 2000, 2006). Despite their species-richness, only five species belonging to three genera have been recorded from Korean waters: Gammaropsis longipropodi Hirayama, 1984; Gammaropsis utinomii (Nagata, 1961); Photis stridulus Jung et al, 2017; Photis longicaudata (Spence Bate & Westwood, 1862); and Podoceropsis clavapes Jung et al, 2017 (Kim et al 2005; Kim and Lee 2010; Jung et al 2017). Additionally, the specimens previously described under the name of P. longicaudata in the Far East (Nagata 1965; Hirayama 1984; Kim et al 2005; Ren 2006) shows several differences to the original description and the specimens reported from the North Sea and the Mediterranean Sea (Bate and Westwood 1863; Sars 1894; Stebbing 1906), so it is doubtful that the material from the Far East belongs to the same species of the North Sea.…”