Diacyclops leeae, Karanovic, Tomislav, Grygier, Mark J. & Lee, Wonchoel, 2013

Karanovic, Tomislav, Grygier, Mark J. & Lee, Wonchoel, 2013, Endemism of subterranean Diacyclops in Korea and Japan, with descriptions of seven new species of the languidoides-group and redescriptions of D. brevifurcus Ishida, 2006 and D. suoensis Ito, 1954 (Crustacea, Copepoda, Cyclopoida), ZooKeys 267, pp. 1-76 : 36-37

Diacyclops leeae sp. n.

Diacyclops suoensis Ito - Lee et al. 2007: p. 162, Figs 7-8; Chang 2009: p. 478, Figs 263-264. Synonymy.

Diacyclops languidoides suoensis n. subsp. - Ito 1954: p. 399, Figs 114-148. [non]

Diacyclops languidoides suoensis Ito - Ito 1957: p. 15, Figs 35-48. [non]

Diacyclops suoensis Ito - Ueda et al. 1996: p. 309, fig. 4. [non]

Type locality.

Korea, Chungcheongbukdo, Danyang city, Yeongchun township, Ha village, Ondal-gul cave, 37°03'43"N, 128°28'59"E, puddles in the cave.

Type material.

Holotype female (illustrated by Lee et al. (2007) in their figures 7 and 8) deposited at the Department of Biological Science, Daegu University, Korea; collected at the type locality, 13 August 2007, leg. J. Lee, Y.G. Choi and W.R. Kim. [not examined]

Etymology.

The species name is dedicated to Dr Jimin Lee (formerly Institute of Basic Science, Daegu University, now Korea Institute of Ocean Science and Technology), who, with co-authors, discovered this population and described it under the name Diacyclops suoensis Ito, 1954 (see Lee et al. 2007). The name is a noun in the genitive singular.

Description.

Female as described by Lee et al. (2007) from Ondal-gul cave, and illustrated in their figures 7 and 8 as Diacyclops suoensis Ito, 1954.

Remarks.

Lee et al. (2007) and Chang (2009) stated that they identified the Korean Diacyclops populations from Ondal-gul cave and the Youncheon-gul lava tube (the latter represented by an unillustrated female) as Diacyclops suoensis Ito, 1954 mainly based on the shape of the seminal receptacle and the elongated dorsal caudal setae. They noted, however, that the dorsal caudal setae are not as elongated as in Japanese populations and also that the caudal rami have somewhat different proportions. Their taxonomic decision possibly reflects the fact that various previous records of this species indicated a wide range in Japan, as well as some variability in the proportions and armature of the caudal rami ( Ito 1954, 1957; Ueda et al. 1996).

After the redescription of Diacyclops suoensis from Japan in this paper (see above), it is quite clear that the Korean specimens found by Lee et al. (2007) are not conspecific with it. Thus, we describe them as a new species, Diacyclops leeae sp. n. The two species are, in fact, only distantly related, which can be judged from their numerous morphological differences in the proportions of the genital double-somite, proportions of the caudal rami, length of the dorsal caudal seta, length of the innermost terminal caudal seta, presence/absence of an exopodal seta on the antenna, number of setae on the second endopodal segment of antenna, etc. The armature of the antenna of Diacyclops leeae probably indicates that this species is not even part of the morphological group formed by the Korean Diacyclops parasuoensis sp. n. and the Japanese Diacyclops suoensis, D. pseudosuoensis sp. n., and Diacyclops hisuta sp. n. (see above).

Diacyclops leeae differs from Diacyclops parasuoensis in the following characters: proportions ot the genital double-somite, proportions of the caudal rami, length of the dorsal caudal seta, length of the innermost terminal caudal seta, presence/absence of exopodal seta on the antenna, number of setae on the second endopodal segment of antenna, length of the proximal seta on the third endopodal segment of the third swimming leg, length of the proximal seta on the third endopodal segment of the fourth swimming leg, relative length of the apical spines on the third endopodal segment of the fourth swimming leg, number of spinule rows on the intercoxal sclerite of the fourth leg, and proportions of the distal segment of the fifth leg. Unfortunately, Lee et al. (2007) and Chang (2009) did not illustrate mouth appendages, so details of these limbs cannot be compared.

Diacyclops leeae seems to be more closely related to Diacyclops languidoides than to Diacyclops parasuoensis . The former species has been recorded from numerous surface-water and subterranean habitats in Korea (see Chang 2009) and is widely distributed in the Palearctic ( Dussart and Defaye 2006). Diacyclops languidoides and Diacyclops leeae share the same armature and ornamentation of the antenna, as well as a similar ornamentation of the fourth leg (especially its coxa and intercoxal sclerite). This may indicate that they shared a recent common ancestor, or even that the stygophilic Diacyclops languidoides gave rise (i.e. is directly ancestral) to the stygobiotic Diacyclops leeae during the major oscillations of its wide distributional range that probably took place during the Pleistocene glacial cycles. This would explain the presence of a population of the languidoides-group in a lava tube on the volcanic Jeju Island, although we cannot be sure if it truly belongs to Diacyclops leeae since Lee et al. (2007) did not provide any illustrations of this population. These inter-relationships need to be studied further, using molecular methods in addition to comparative morphology. The two species mainly differ in the proportions of the caudal rami (longer in Diacyclops languidoides ) and the relative length of the third endopodal segment of the fourth leg ( Chang 2009). However, the very wide distribution of Diacyclops languidoides , with numerous described subspecies (see Dussart and Defaye 2006) and several reports of its extreme morphological variability both from Asia (i.e. Ito 1954) and Europe (i.e Kiefer 1968), probably indicate that it is a complex of species, as is the case for many other widely distributed freshwater cyclopoids ( Monchenko 2000; Blàha et al. 2010; Karanovic and Krajicek 2012a).

Chang (2009) reported records of Diacyclops suoensis from four different localities in Korea in addition to Odal-gul cave and the Yoncheon-gul lava tube, but without any additional comments on morphological variability, and he only republished the drawings of Lee et al. (2007). It is thus impossible for us to confirm whether any of these populations is in fact conspecific with Diacyclops leeae or perhaps with Diacyclops parasuoensis .