Leydigia (Neoleydigia) cf. striata Birabén, 1939

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 : 71-74

XII. Leydigia (Neoleydigia) cf. striata Birabén, 1939

( Figs 376–381 )

Leydigia acanthocercoides (Fischer) in Daday 1902, p. 185, Pl. 11: fig. 19.

Leydigia striata in Birabén 1927, p. 573 (nomen nudum).

Leydigia striata Birabén, 1939, p. 661 –663, figs 14–16; Olivier 1962, p. 245, Pl. 15: figs 3–4.

Leydigia cf. striata Birabén, 1939 in Kotov et al. 2003b, p. 190 –194, figs 64–85; Kotov and Elías-Gutiérrez 2004, p. 1 –5, figs 1–28.

Leydigia ciliata Gauthier in Harding 1955, p. 242 –243, figs 50–60; Smirnov 1971, p. 454 –458 (only Neotropical populations); Infante 1980, p. 600, fig. 8; Valdivia Villar 1985, p. Tab. 2, fig. 6.

Type locality. "...el canal de entrada al Puerto de La Plata" ( Birabén 1939), Atlantic coast of Argentina near Buenos Aires .

Type material. Apparently lost.

Material examined earlier. See Kotov et al. (2003b) for list of material from Paraguay, Brazil, Peru, Mexico.

Additional material examined here. Brazil. Amazonas: Lago do Castanho , coll. by G.-O. Brandorff, tube NMK 0759 ; Mato Grosso do Sul: A pond 10 km S. from Corumbá , Pantanal, coll. 15.12.1982 by H. J. Dumont, tube NNS 1997-262 .

Diagnosis. Parthenogenetic female. Body subovoid, maximum height in posterior half, dorsal margin slightly curved to almost straight in posterior part, postero-dorsal angle rounded, but recognisable. Coarse striation from distinct to obscure, present, but small-scale striation always distinct ( Figs. 376–377 ). Eye smaller than ocellus, but size of ocellus very variable. Head shield wide, PP = 4–5 IP, lateral head pores at level of central major pore. Labral keel wide, triangular-ovoid, posterior margin with groups of small setules, anterior margin with fringe of long setules, which reach the apex, setules in lateral groups as long as marginal setules. In middle of valve ventral margin, setae with short setulation, relatively long setules between their bases. In postero-ventral region, these setae setulated asymmetrically. Posterior to last marginal seta, setules in successive pectens, ventralmost setules (closest to the proximalmost marginal seta) especially robust. On inner side of carapace, a row of small setules some distance from posterior margin of valve, marginal membrane with minute 'setules'.

Postabdomen narrow, maximum width in middle, ventral margin almost straight. Preanal margin somewhat shorter than anus, with 3–4 distinct hillocks, preanal angle well defined, postanal angle less distinct, but present. Postanal margin slightly curved, often almost parallel to ventral margin in middle. Dorsodistal angle absent, base of claws separated from postanal margin by shallow depression, or latter completely absent. Postanal marginal denticles in successive series of 3–5 denticles, size increasing distad in each series, 7–9 fascicles of long lateral setae, decreasing in size basally, 2–4 setae in each fascicle, marginal setae of each fascicle longest, medialmost seta frequently rudimentary, sometimes fascicles of 2 setae only posteriorly. Distal segment of postabdominal seta with dense setules. Postabdominal claw as long as preanal plus anal portions of postabdomen, basal spine rudimentary or present only as smoothed hillock.

Antenna I not reaching tip of rostrum, 4 transverse rows of long setules on anterior face, and series of setules at tip. Sensory seta half as long as appendage, arising 1/4–1/3 of way from tip. Antenna II with 2–3 (rarely 4) spine-like setules on first and second endopod segments. No chitinous insertions within distal segments of swimming setae.

Trunk limb I with ODL large, elongated, with a long seta, distal segment unilaterally, sparsely setulated. IDL with three medial clusters and 3 marginal clusters of setules, in basalmost cluster setules short, in others longer. On endite 3 seta 1 densely setulated, on endite 2 setae e and f of significantly different size. Trunk limb II exopodite small, armed with short setules apically; scraper 1 with basal segment fully setulated and distal segment setulated by long setules unilaterally, located on distal lobe with basal group of long setules and distal tuft of short setules. Trunk limb III exopodite with seta 1 with distal segment bilaterally setulated, basal segment fully setulated, seta 2 with long setules of different sizes on distal segment, rudimentary seta 3. Trunk limb IV pre-epipodite large, with long marginal setules; epipodite lage, with setae 2 and, especially 1, short and setulated distally with long setules. All setae of filter plate of gnathobase IV with inflated tips. Trunk limb pre-epipodite small, armed as in limb IV, epipodite large. Inner portion of limb with two setulated setae of subequal length.

Ephippial female. Basically similar to parthenogenetic, but with slightly higher body. In anterior view body more compressed laterally, with expanded region of egg, and low, thick dorsal keel. Ephippium with single resting egg, region of egg chamber pigmented in brown colour, with an additional low, honeycombed sculpture, plus small-scale striae disrupted into lines of minute dots.

Adult male. Body triangular-ovoid, head large, rostrum elongated ( Figs 378–380 ). Postabdomen elongated ( Fig. 381 ), with slightly convex ventral and dorsal margins, in the middle two margins parallel, preanal margin without hillocks. Base for claws and penis inflated, distal margin of postabdomen ill-defined, dorsal margin with obscure preanal and postanal angles. Marginal denticles somewhat smaller than in female, only 7 lateral fascicles of large setae, shorter than in female. Postabdominal claw more slender than in female, no trace of basal spine. Penis thick, shorter than claw, with stylet at tip.

Antenna I robust, with transverse rows of setules on anterior surface, and 12 aesthetascs of unequal length, additional male seta thick, as long as longest aesthetasc, protruding at some distance from distal end. Sensory seta longer than longest aesthetasc, slender, protruding at 1/4 of way from tip.

Trunk limb I with with U-shaped copulatory hook, ODL as in female, but basal segment of ODL seta also setulated. IDL with 3 setae of subequal size: male seta, and two largest setae of IDL with different setulation (as in female), shortest of IDL setae absent. Copulatory brush consisting of long, fine setules, copulatory brush setae long, with inflated basal part.

Size. Parthenogenetic females 660–950 µm, ephippial females 688–760 µm, adult male about 700 µm.

Full redescription, taxonomical comments. See Kotov et al. (2003b) and Kotov and Elías-Gutiérrez (2004).

Differential diagnosis. In contrast to all other acanthocercoides -like species, only in L. striata and L. ipojucae the distalmost scraper of limb I has a setulated basal segment, but the setules in lateral fascicles on labrum in L. striata are of the same size as marginal setae. Also, the penis is supplied with a stylet in L. striata , and the postabdomen of the female is the most narrowest among all species of the acanthocercoides -group. In the Neotropics it can be also separated from ipojucae by the presence of distinct hillocks on the preanal margin of the postabdomen in the former.

Distribution. Neotropical zone from Argentina to South of Mexico.

Figures

FIGURES 376–381. Leydigia cf. striata from ephemeral dune pools in the eastern border of the Lençóis Maranhenses dune field, Maranhao, Brazil coll. 23.12.1997 by K. Van Damme (376–377), and a pond near Lake Titicaca, Peru, collected 30.04–11.09.1937 by the Percy Sladen Trust Titicaca Expedition (378–381). 376–377. Juvenile and reticulation of its valve. 378–381. Adult male, its head and posabdomen. Scale bar denotes 100 µm for 100 µm for 376, 378–381; 10 µm for 377.