Leydigia louisi Jenkin, 1934

Lee, Sue Yeon, Yoo, Jung Sun & Kim, Seung Tae, 2017, Recent progress in studies of the Cladocera (Crustacea: Branchiopoda) of South Korea with seven new records for the Korean Peninsula, Journal of Species Research 6, pp. 227-246 : 243-244

9. Leydigia louisi Jenkin, 1934

Material deposited to NIBR. Daedong pond (a large dam lake covered by Trapa sp. ) (N 35.9634°, E 129.224°), Gyeongsangbuk-do, coll. in 14 Jul 2017 by A.A. Kotov and K.S. Chae, NIBRIV0000812489 .

Parthenogenetic female. Body moderately compressed laterally, in lateral view subovoid, dorsal margin strongly convex, postero-dorsal angle ill-defined. A fine reticulation better visible in postero- and antero-ventral valve portions, both coarse and fine striation absent. Head small, compound eye and ocellus subequal in size. Three large head pores, postpore distance about 5 interpore distances, lateral head pores located closely to major pores. Labral keel widely-triangular-ovoid, with distinct apex, its anterior margin with fringe of very hort setules, lateral groups setules absent. On posterior margin, a row of setules on inner side of valve, located far from margin. Postabdomen broad, subovoid, preanal margin shorter than anus, without projections, preanal and postanal angles well defined, no distal margin and no dorso-distal angle. Distal portion of postabdomen with fascicles of stout lateral setae, decreasing in size basally, the longest seta length more than half of postabdominal claw length. Postabdominal claw with basal spine not adpressed to it. Antenna I not reaching tip of rostrum, with 4 transverse rows of short setules at anterior face, sensory seta long. Largest aesthetasc less than half length of appendage. Antenna II with few stout spine-like setules on first and second endopod segments; a strong spine on proximal segment of exopod longer that the next segment; chitinous insertions within distal segments of the swimming setae. Limbs are not studies, see Yoon (2000). Size in our material 0.7 mm.

Notes. Only a single deformed female was found, therefore this diagnosis is incomplete. Korean populations have: (1) body moderately (not strongly) compressed laterally; (2) a strongly convex dorsal margin with ill-defined postero-dorsal angle; (3) fine reticulation on valves; (4) very long lateral setae on the postanal portion of postabdomen (the longest seta length is more than half of the postabdominal claw length); (5) chitinous insertions within distal segments of the swimming setae. Such traits are characteristic for L. louisi , not L. leydigi . It is obvious that Yoon (2000, p. 124-125, figs. 67-68) described and illustrated the same taxon under the name L. leydigi Schödler. To date, the former was recorded from Afrotropical and Neotropical regions only ( Kotov, 2009). It is necessary, however, to consider that Korean populations have: (1) lateral head pores located closely to major pores; (2) a basal claw on postabdomen not addressed to the postabdominal claw. Most likely, Korean populations belong to an undescribed taxon from the leydigi -group, but our material is not adequate to establish this.

This is a new record for the Korean Peninsula (and the whole of Asia!). This taxon should be regarded as a member of the southern thermophilic complex sensu Kotov (2016). We observed only leydigi -like populations in the closest regions: Far Eastern Russia and Japan. This means that such populations could be found in Korea as well. It is obvious that the L. leydigi group needs to be revised in Asia.