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Protistology 13 (2), 64-66 (2019)
Protistology
Planhoogenraadia liboica sp. nov. a new testate amoebae species from mountain forest soils in China
Anatoly Bobrov
Lomonosov Moscow State University, Moscow, 119991, Russia | Submitted March 6, 2019 | Accepted March 20, 2019 |
Summary
The article presents a description of a new species of testate amoebae from the genus Planhoogenraadia, which belongs to the Gondwana-tropical group oftestate amoebae. The species was found in the mountain forest of the subtropical zone of Central China (Hubei Province).
Key words: testate amoebae, Planhoogenraadia liboica sp. nov., China
Introduction
Testate, or shell, amoebae inhabit almost all types of biotopes and have a global distribution. They are a key component of soil ecosystems and are actively involved in the biogenic cycles of carbon, nitrogen, phosphorus, silica and calcium. They play an important role in regulating the abundance of microorganisms in soils. Since late 19th century, a development of the micropaleontological method in paleoecology was known as a rhizopod analysis (Beyens and Bobrov, 2016).
The shell amoebae from the genus Planhoogenraadia in the eastern part of Eurasia, namely in the Far East, were first found in 2001 (Bobrov, 2001). Later they were also found in Thailand (Todorov and Golemansky, 2014). The genus Planhoogenraadia inhabits the forest soils. The genus belongs to the Gondwana-tropic group of shell amoebae and has a limited geographical distribution (Bonnet, 1984; Bonnet and Gomez-Sanchez, 1984). This is one of the most interesting genera in protozoology in view ofbiogeography (Foissner, 2006; Smith et al., 2018). The soil fauna of shell amoebas of the subtropics
and tropics is still poorly studied (Qin et al., 2011; Bobrov et al., 2015).
This study was conducted in a mountain subtropical forest near the city of Wuhan, Hubei Province, Central China.
Material and methods
The new species was found in soils of the Nan-wangshan and Yujiashan Mountains near Wuhan City, central China. The vegetation was a forest dominated by Cinnamomum camphora (camphor tree). Ground floor included Deyeuxia langsdorffii. The climate of this territory is humid subtropical, affected by the East Asian monsoon (Qin et al., 2013). Mean air temperature in July is 29.3 °C, in January — 3 °C. Annual mean precipitation is 1205 mm, primarily occurring in the summer months.
The samples of the upper layer of soil (0-2 cm) were taken on the slopes and placed in plastic containers. In the laboratory, coarse mineral particles and large plant pieces were removed. Then the aqueous suspension was filtered through a 250
doi:10.21685/1680-0826-2019-13-2-3 © 2019 The Author(s)
Protistology © 2019 Protozoological Society Affiliated with RAS
Protistology ■ 65
Table 1. Morphometric characteristics of Planhoo-genraadia liboica sp. nov. testate amoebae from subtropical forest soils in Wuhan.
Taxa Features Min Max Mean SD CV (%) N
1 shell length 83 93 89 3.5 3.9 12
2 shell width 56 69 64 3.7 5.8 12
3 shell height 48 64 59 4.4 7.4 12
4 aperture height 9 15 12 1.7 13.8 12
5 aperture width 29 41 36 3.4 9.6 12
6 cap length 15 19 17 0.9 5.3 12
Notes. Measurements in jm. SD - standard deviation; CV - coefficient of variation in %; Min - minimum; Max - maximum; N -number of individuals investigated.
^m sieve. Two or three drops ofthe suspension were analyzed using a Carl Zeiss Axioplan 2 microscope with magnifications of * 200 and *400. Twelve shells ofthe new species were analyzed for morphometry in the samples, because Planhoogenraadia abundance was low, since they almost always belong to a minority group in soil communities of the amoebae (Bonnet, 1984). The subjects of morphometric analysis were: 1) shell length, 2) shell width, 3) shell height, 4) aperture height, 5) aperture width, and 6) cap length (Figs 1 and 2). Previously we have described a new species, Planhoogenraadia wuchanica, from this forest (Bob-rov et al., 2019), which is morphologically and morphometrically different from Planhoogenraadia liboica sp. nov. described here (Table 1).
Results and discussion
Description of Planhoogenraadia liboica sp. nov.
Description. The test is relatively flat, with a dorsal convexity (Figs 1 and 2). The shell is the widest in the center. The aperture is deep and narrow, with depth from 15 to 19 ^m and width from 29 to 41 ^m. The upper lip of the aperture has a distinct cap-like structure. The upper part ofthe shell of P. liboica is flattened, giving a distinctly different profile from other species ofthis genus. The posterior of the shell meets the ventral side at a blunt angle which is clearly distinct from the smooth transition in Planhoogenraadia wuhanica. The coefficients of variation ofmost measured variables are below 10% (Table 1).
Measurements. Shell length 89 ± 3.5 ^m; shell width 64 ± 3.7 ^m.
Habitat. Soil of subtropical forest dominated
Fig. 1. Outline of Planhoogenraadia liboica sp. nov. in ventral (A) and lateral (B) views. Scale bar — 50 ^m.
by Cinnamomum camphora (camphor tree) and the grass Deyeuxia langsdorffii.
Etymology. The species name 'liboica' is in reference to the Tang dynasty poet 'Li Bai' (also known as Li Bo), who lived in the province of Hubei for ten years.
Type locality. The type locality of the species is surface soil in Cinnamomum camphora dominated subtopic forest in the Nanwangshan and Yujiashan mountains and behind the campus ofChina University of Geosciences in Wuhan, central China.
Type specimens. The holotype specimens of Planhoogenraadia liboica on which morphometric analyses were based, are stored at China University of Geosciences, Wuhan, China (reference YJS17-2).
Ecology. Individuals described here were located in subtropical soils in the forest dominated by Cinnamomum camphora and Deyeuxia langsdorffii. Geographical distribution. Central China. Taxonomy
Arcellinida Kent 1880 Plagiopyxidae Bonnet 1984 Genus Planhoogenraadia Bonnet 1977a, 1977b Planhoogenraadia liboica Bobrov et Qin (Fig. 1) Comparison with similar species The ventral region of Planhoogenraadia liboica is flat. This species differs from the most similar previously described species Planhoogenraadia alta by smaller shell size, specifically smaller shell length and narrower shell width. P. liboica has a broader shell than other similar taxa; the mean shell length/shell width ratio is 1.4 compared to 2.2 for Planhoogenraadia acuta, 1.5 for P. alta, and 1.9 for Planhoogenraadia asturica. P. liboica is similar in morphology to P. alta with the exception ofthe blunt angle between the posterior end and ventral side of the shell. The size of P. liboica shell is smaller than
66 • Anatoly Bobrov
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Fig. 2. Light microscopical image of Planhoogen-raadia liboica sp. nov. A — Ventral view; B — lateral view. Scale bar - 50 ^m.
in Planhoogenraadia wuchanica with shell length Min - 106, Max - 134 ^m and shell width Min - 60, Max - 92 ^m (Bobrov et al., 2019).
Conclusions
The fauna oftestate amoebae in China, considering the diversity of habitats of the country, is poorly studied. The history of the formation of these zones is also different. This means that the discoveries of new species of shell amoebas in China's soils will not be limited to subtropics. Of special interest are the populations of water bodies, primarily lakes, as well as wetlands (Qin et al., 2016). Expansion of the studies of soil biota could have significantly enhanced the understanding of the biogeography of the microbiota of this vast and diverse region ofAsia.
Acknowledgements
I thank S. Yazvenko (LGL) and R.J. Payne (University of York) for editing the English version of this paper and Yangmin Qin (University of Geoscience, China) for collecting samples for taxo-nomic analysis.
References
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Address for correspondence: Anatoly A. Bobrov. Department of Soil Science, Lomonosov Moscow State University, Leninskiye gory, Moscow, Russia, 119234. Russia; e-mail: anatoly-bobrov@yandex.ru
