Leydigia (Leydigia) Kurz, 1875

Kotov, Alexey A., 2009, A revision of Leydigia Kurz, 1875 (Anomopoda, Cladocera, Branchiopoda), and subgeneric differentiation within the genus, Zootaxa 2082 (1), pp. 1-84 : 11-12

Subgenus Leydigia (Leydigia) Kurz, 1875

Leydigia leydigi -group in Kotov 2003, p. 166.

Type species. Leydigia quadrangularis (Leydig) in Kurz, 1875, which is a junior synonym of Alona leydigi Schoedler, 1863 .

Diagnosis of the nominal subspecies. Sufficient characters. (1) A fine (small-scale) striation on valves completely absent; (2) basal spine on postabdominal claw large (as long as the claw diameter at the base); (3) setae 1 and 2 on exopodite IV with short setules.

Necessary characters. (4) On labral keel, setulation of anterior margin short, not reaching apex, few lateral fascicles of short setules, no setules on its posterior margin; (5) setules between setae in the middle of ventral margin short; (6) preanal margin of postabdomen without hillocks; (7) exopodite III with five large setae.

Taxonomic comments. Kotov (2003) proposed a L. leydigi -group, and pointed out its possible monophyly. This point of view is confirmed by my cladistic analysis. Three consistent features are sufficient to separate two subgenera within Leydigia . At this moment, only Palaearctic representatives of the subgenus are relatively well studied (Kotov 2003; Kotov et al. 2003a). In contrast, only a few populations are determined accurately from South and Central America and Africa. All South American, African, Asian, and Australian records ( Brehm 1954; Olivier 1962; Dumont et al. 1979; Biswas 1980; Smirnov & Timms 1983) must be checked. Some of them may be dealing with members of the other subgenus, because in previous keys the main feature used to discriminate between leydigi and other species (the basal spine expression) was formulated inaccurately (see discussion).

Leydigia macrodonta longiseta Chen Shou-zhong, 1992 is not a subspecies of L. macrodonta , but a member of the leydigi -group. Probably, it is a valid species, more closely related to L. leydigi than to L. louisi , having a slightly convex dorsal margin, short lateral setae, and the lateral head pores located near the major pores. But the male postabdomen (in the author’s figure) is shown as significantly narrowing distally and as lacking a distal margin. The first description (Chen Shou-zhong 1992) was lacking in detail, and a final conclusion on the status of this form can only be obtained after a re-investigation of the original material.

Leydigia macrodonta var. louisi in Shen Chia-jui and Sung Ta-hsiang (1962) is a misidentification: the animal, with heavily striated valves, is not a member of the leydigi -group.