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Arthropoda Selecta 14 (2): 113115

ї ARTHROPODA SELECTA, 2005

Notes on the genus Ilyocryptus Sars, 1862 (Cladocera: Anomopoda: Ilyocryptidae). 5. On male of Ilyocryptus brevidentatus Ekman, 1905 Заметки о роде Ilyocryptus Sars, 1862 (Cladocera: Anomopoda: Ilyocryptidae). 5. Самец Ilyocryptus brevidentatus Ekman, 1905 Alexey A. Kotov1 & Pavel Stifter А. А. Котов и П. Штифтер
1

2

A. N. Severtsov Institute of Ecology and Evolution, Leninsky Prospect 33, Moscow 119071 Russia. E-mail: golokot2000@mail.ru. Институт проблем экологии и эволюции им. А. Н. Северцова РАН, Ленинский проспект 33, Москва 117071 Россия. 2 Smetanova 25, Benatky nad Jizerou 29471 Czech Republic. E-mail: stifter@benatky.cz.

KEY WORDS: Cladocera, Anomopoda, Ilyocryptus, morphology, male, South America. КЛЮЧЕВЫЕ СЛОВА: ветвистоусые ракообразные, Cladocera, Anomopoda, Ilyocryptus, морфология, самец, Южная Америка.

ABSTRACT. The unknown male of Ilyocryptus brevidentatus Ekman, 1905 is described from a pond in Tierra del Fuego, Argentina. РЕЗЮМЕ. Ранее неизвестный самец Ilyocryptus brevidentatus Ekman, 1905 описан по материалу из пруда на Огненной Земле, Аргентина.

Results
Ilyocryptus brevidentatus Ekman, 1905 Figs 113.
DESCRIPTION OF MALE. Body triangular-ovoid in lateral view (Fig. 1),less high than in female (BH/BL = 0.74 0.77 versus 0.780.86 in females), but body thickness as in female, and dorsal keel also massive and low. Head large, in lateral view with a rounded distal extremity (Fig. 2); eye large, but ocellus, in contrast to female, relatively small. Labrum with massive projection in its basal portion. Abdomen with well-developed transverse rows of setules, projection on first segment small (Fig. 3). Postabdomen very similar to that in female, with gonopore opening near its base (Fig. 3, arrow). Preanal margin somewhat shorter than in female (PR/PL = 0.590.62 versus 0.620.68 in females) slightly convex, preanal teeth relatively small and numerous (NT = 1819), slightly bent toward distal end, no denticles at base of postabdomen; 79 paired spines large and rarely distributed, their row reaches anus; largest lateral setae reduced in number (NL = 7 8 versus 1012 in females), smaller than the spines and located far from postanal contour, their row also reaches the anus. Rudimentary setules near base of postabdominal claw numerous (Fig. 4). No denticles in distal portion of postabdominal claw, distalmost spine on base of postabdomen somewhat longer than basalmost spine. Postabdominal setae as in female, long and with distal segment bearing numerous, short setules (Fig. 5). Antenna I large (AL/BL = 0.210.22), markedly thicker than the female antennae (DA/AL = 0.260.28 versus 0.150.17 in female), basal segment with low hillocks, but without a finger-like projection (Figs 6, 7). Distal segment markedly extended and with an additional male seta located in middle (Fig. 2, arrow), this seta as long as half of the segment. End of antenna I with a concentric row of low hillocks (smaller than those in female) and ten aesthetascs, two of them markedly long, next three aesthetascs somewhat shorter that

Introduction
The genus Ilyocryptus Sars, 1862 (Cladocera: Anomopoda: Ilyocryptidae) has recently been revised [ tifter, 1991; Kotov et al ., 2002; Kotov & tifter, 2005]. However, males are unknown or poorly described for m ost valid species of the genus. For example, Kotov et al. [2002] recently redescribed I. brevidentatus Ekman, 1905, but no males were available. Here we describe gamogenetic specimens of I. brevidentatus , obtained from the collections of the late Prof. D.G. F rey in Bloomington, U.S.A.

Material and methods
In total, the examined sub-sample from the sample DGF 89-45 contained 21 parthenogenetic , 2 ephippial , 2 ephippia, 8 exuvia, and 5 adult from a pond E of Route E crossing the Rio MacLenan, Tierra del Fuego, Argentina, collected on 17.i.1989 by D.G. Frey. See previous articles for methods and abbreviations of measured parameters.


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A.A. Kotov & P. tifter

Figs 113. Ilyocryptus brevidentatus, adult from a pond E of Route E crossing the Rio MacLenan, Tierra del Fuego, Argentina, collected in 17.i.1989 by D.G. Frey: 1 lateral view; 2 head; 3, 4 postabdomen and its distal portion; 5 postabdominal seta; 6, 7 proximal segment of antenna I in lateral and anterior view; 8 distal end on antenna I; 9 antenna II; 10, 11 apical and proximal lateral swimming seta; 12 spine on second segment of exopod af antenna II; 13 distal portion of limb I. Scale 100 чm. Рис. 113. Ilyocryptus brevidentatus, взрослые из пруда западнее пересечения трассы E и реки Мак Ленан, Огненная Земля, Аргентина, собранные Дэвидом Фраем 17 января 1989 г.: 1 вид сбоку 2 голова; 3, 4 постабдомен и его дистальная часть; 5 постабдоминальная щетинка; 6, 7 проксимальный членик антенны I, вид сбоку и спереди; 8 дистальный конец антенны I; 9 антенна II; 10, 11 апикальная и проксимальная латеральная плавательные щетинки; 12 шип на втором членике антенны II; 13 дистальная часть ноги I. Масштаб 100 чm.


Ilyocryptus brevidentatus male
the former, other aesthetascs significantly smaller (Fig. 8). In reality, one of these aesthetascs (apparently among larger members) is another additional male seta. Antenna II as in female (Fig. 9), apical and lateral swimming setae (Figs 10, 11) as in female. Spine on second segment of exopod, as in female, naked, with blunt tip (Figs 9, 12). Limbs as in female, limb I not modified (Fig. 13), as in all other studied species.

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of antenna I in male of I. brevidentatus is an autoapomorphic character, which was not known for any other species with well-described males.
ACKNOWLEDGEMENTS. We are very grateful to Prof. N.N. Smirnov for help at different stages of our work, and the late Prof. D.G. Frey for the material and help during visit of PS to U.S.A. This work is supported by the Russian Foundation for Basic Research (grant 03-04-48879 for AAK) and US National Science Foundation grant PEET (DEB0331095).

SIZE. 590615 чm (n = 5) versus 470905 чm in females (n = 21) from the same sample.

Discussion
Unfortunately, it is difficult to discuss differences between males of different ilyocryptid species due to absence of information on majority of them. In contrast to many other anomopods, sexual dimorphism is reduced in ilyocryptids [Smirnov, 1976]. Gonopores opening at the postabdomen base and absence of a copulatory hook on limb I are among most distinctive traits of the family I lyocryptidae Smirnov, 1976 emend. Smirnov, 1992. Only antenna I in ilyocryptid males is modified as compared with females. In some species, i.e. I. spinifer, I. agilis, and some others (see Kotov [1999]; Kotov & Williams [2000]), it is supplied terminally with three very long aesthetascs (one of them is the additional male seta, see above), while other aesthetascs are significantly smaller and of subequal size. In other species, i.e. I. brevidentatus or I. denticulatus (see Kotov & Stifter [2005]), antenna I is more primitive, differences between aesthetascs are not too obvious. At the same time, a very thick distal segment

References
Kotov A.A. 1999. Morphology and variability of Ilyocryptus agilis Kurz, 1878 and Ilyocryptus cuneatus tifter, 1988 from Lake Glubokoe, Moscow Area, central Russia (Anomopoda: Branchiopoda) // Arthropoda Selecta. Vol.8. No.1. P.322. Kotov, A.A., tifter P. 2005. Notes on the genus Ilyocryptus Sars, 1862 (Cladocera: Anomopoda: Ilyocryptidae). 6. South American I. denticulatus denticulatus Delachaux, 1919 and I. denticulatus freyi subsp.n. // Arthropoda Selecta (in press). Kotov A.A., Williams J.L. 2000. Ilyocryptus spinifer Herrick 1882 (Anomopoda, Branchiopoda): a redescription based on North American material and designation of a neotype from Minnesota // Hydrobiologia. Vol.428. P.6784. Kotov A.A., Paggi J.C., Elнas-Gutiйrrez M. 2002. Redescription of Ilyocryptus brevidentatus Ekman, 1905 (Anomopoda, Cladocera, Branchiopoda) // Hydrobiologia. Vol.481. P.118. Smirnov N.N. 1976. [Macrothricidae and Moinidae of the Worid fauna] // Fauna SSSR, n. ser., Rakoobraznye T.1. No.3, Leningrad: Nauka Publ. 237 pp. [in Russian]. tifter P. 1991. A review of the genus Ilyocryptus (Crustacea: Anomopoda) from Europe // Hydrobiologia. Vol.225. P.18.