Simocephalus (Echinocaudus) exspinosus ( De Geer, 1778 )

Sinev, Artem Y., Dadykin, Ivan A., Umi, Wahidah A. D. & Yusoff, Fatimah M., 2025, New data on Cladocera (Crustacea: Branchiopoda) of Peninsular Malaysia, Zootaxa 5604 (3), pp. 255-284 : 257

publication ID	https://doi.org/10.11646/zootaxa.5604.3.3
publication LSID	lsid:zoobank.org:pub:C8E5E697-223C-45A0-A104-134328213586
DOI	https://doi.org/10.5281/zenodo.15046315
persistent identifier	https://treatment.plazi.org/id/03F2AF08-FFB5-FFC2-C7D2-27B0FB98F85B
treatment provided by	Plazi (2025-03-16 17:36:46, last updated 2025-03-18 16:18:37)
scientific name	Simocephalus (Echinocaudus) exspinosus ( De Geer, 1778 )
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Simocephalus (Echinocaudus) exspinosus ( De Geer, 1778) View in CoL s. lato

Figs. 1A–E View FIGURE 1

De Geer 1778: 457 ( Monoculus ); Flössner 1972: 184–187, Fig. 87; Orlova-Bienkowskaja 2001: 76–78, Figs. 94–99, Pl. 33–34; Hudec 2010: 160–161, Fig. 32J–M; Rogers et al. 2019: 679, Figs. 16.2.18; Korovchinsky et al. 2021b: 163, Figs. 48, 9–10.

Material examined. Numerous parthenogenetic females from a pond in Permai Lake, Ipoh, Perak (4.47728° N, 101.0492° E), 28.01.2018.

This is the first record for Peninsular Malaysia. Studied specimens have typical general morphology ( Fig. 1A View FIGURE 1 ) and morphology of postabdomen ( Fig. 1B View FIGURE 1 ), with the outer side of the postabdominal claw bearing a pecten of spines near the base ( Figs. 1C–D View FIGURE 1 ). Studied specimens have clusters of darkly pigmented hypodermal cells on the valves ( Figs. 1A, E View FIGURE 1 ), but such pigmentation was not recorded in populations from temperate regions. The species was recorded in the Sarawak State, East Malaysia by Spandl (1925). In South-East Asia, it was recorded in Thailand ( Sanoamuang 1998; Maiphae et al. 2008), Vietnam ( Sinev & Korovchinsky 2013, as S. congener (Koch, 1841)) and Indonesia ( Korovchinsky 2013). According to Orlova-Bienkowskaja (2001), S. expinosus has a cosmopolitan distribution, as well as its sibling-species, S. congener . These two taxa differ only in the morphology of the postabdominal claw: S. congener has a pecten of 20–25 thin spines on the outer side instead of 8–12 large spines in S. expinosus . In our materials, we found specimens with intermediate number of spines (15–18), which was also observed in populations from Vietnam ( Sinev & Korovchinsky 2013) and Central China ( Dadykin et al. 2023). Thus, we consider S. congener as possible synonym of S. expinosus , despite this should be tested using molecular methods. For detailed description, see Orlova-Bienkowskaja (2001).

References

Dadykin, I. A., Sinev, A. Y., Gu, Y. & Han, B. (2023) Spring and autumn fauna of Cladocera (Crustacea: Branchiopoda) in thecenter of East Asia plain: Hunan and Hubei provinces of China. Zootaxa, 5380 (1), 1-25. https://doi.org/10.11646/zootaxa.5380.1.1

De Geer, C. (1778) Memoires pour servir a l'histoire des insectes. 7. L'imprimerie de Pierrre Hesselberg, Stockholm, 950 pp.

Flossner, D. (1972) Krebstiere, Crustacea. Kiemen- und Blattfusser, Branchiopoda. Fischlause, Branchiura. Vol. 60. Die Tierwelt Deutschlands und der angrenzenden Meeresteile nach ihren Merkmalen und nach ihrer Lebensweise, Fischer Verlag, Jena, 501 pp.

Hudec, I. (2010) Fauna Slovenska III. Anomopoda, Ctenopoda, Haplopoda, Onychopoda (Crustacea: Branchiopoda). Veda, Bratislava, 496 pp.

Korovchinsky, N. M. (2013) Cladocera (Crustacea: Branchiopoda) of South-East Asia: history of exploration, taxon richness and notes on zoogeography. Journal of Limnology, 72 (S 2), 109-124. https://doi.org/10.4081/jlimnol.2013.s2.e7

Korovchinsky, N. M., Kotov, A. A., Sinev, A. Y, Neretina, A. N. & Garibian, P. G. (2021 b) The water fleas (Crustacea: Cladocera) of North Eurasia. Vol. 2. KMK, Moscow, 544 pp. [in Russian]

Maiphae, S., Pholpunthin, P. & Dumont, H. J. (2008) Taxon richness and biogeography of the Cladocera (Crustacea: Ctenopoda, Anomopoda) of Thailand. International Journal of Limnology, 44 (1), 33-43. https://doi.org/10.1051/limn:2008021

Orlova-Bienkowskaja, M. Y. (2001) Daphniidae: genus Simocephalus. Guides to the identification of the microinvertebrates of the continental waters of the World 17. Backhuys, Leyden, 130 pp.

Rogers D. C., Kotov A. A., Sinev A. Y. Glagolev S. M., Korovchinsky, N. M., Smirnov, N. N. & Bekker, E. I. (2019) Chapter 16.2. Arthropoda: Class Branchiopoda. In: Rogers, C. D., Thorp, J. H. (Eds.), Thorp and Covich's Freshwater Invertebrates. Vol. 4. Keys to Palaearctic Fauna. Academic Press, London, pp. 643-724. https://doi.org/10.1016/B978-0-12-385024-9.00018-6

Sanoamuang, L. (1998) Contributions to the knowledge of the Cladocera of northeast Thailand. Hydrobiologia, 362, 45-53. https://doi.org/10.1023/A:1003111401684

Sinev, A. Y. & Korovchinsky, N. M. (2013) Cladocera (Crustacea: Branchiopoda) of Cat Tien National Park, South Vietnam. Journal of Limnology, 70 (S 2), 125-141. https://doi.org/10.4081/jlimnol.2013.s2.e8

Spandl, H. (1925) Entomostraken von Borneo. Annalen des naturhistorischen Museums in Wien, 38, 89-95.

Figures

FIGURE 1. Simocephalus (Echinocaudus) exspinosus (De Geer, 1778) from pond at Permai Lake, Ipoh, Perak, Malaysia, parthenogenetic female. A, lateral view. B, postabdomen, С, postabdominal claw from outer side. D, basal portion of postabdominal claw from outer side. E, group of pigmented hypoderm cells on valves. Simocephalus (Simocephalus) mixtus Sars, 1903 pond at the Permai Lake, Ipoh, Perak, Malaysia, F, lateral view. G, head. H, posteroventral angle of valves. I, postabdomen. J, basal portion of postabdominal claw from outer side.