Latitudinal Diversity Gradients in Free-living Microorganisms – Hoogenraadia a Key Genus in Testate Amoebae Biogeography

The extent to which free-living microorganisms show cosmopolitan distributions has been a contentious aspect of microbial ecology over the last few decades. Testate amoebae are a group of free living protists that can provide important evidence for the nature of the biogeography of microorganisms because there are relatively good data on the distribution of their morpho-species (compared to many other microbial groups). Many testate amoebae appear to exhibit ubiquitous distributions, while some taxa have proven to be endemic to limited regions. The genus Hoogenraadia (Gauthier-Lièvre and Thomas 1958) is of particular interest in this context as it appears to be restricted to relatively low latitudes. There are six described species of the genus: H. africana Gauthier-Lièvre and Thomas 1958, H. asiatica Wang and Min 1987, H. cryptostoma Gauthier-Lièvre and Thomas 1958, H. humicola Bonnet 1976, H. ovata Bonnet 1976, and H. sylvatica Vucetich 1974. However, information on these taxa is scattered through a number of different papers – here we provide a summary of what is known about the taxonomy and ecology of this genus. We also reinterpret recent new records of putative H. africana from China (suggesting this identification is not reliable). As an example of a protist taxon largely restricted to the tropics this genus is of particular interest in microbial biogeography and this paper discusses its morphology, ecology and distribution in this context

ANATOLY BOBROV, YANGMIN QIN & RICHARD J. PAYNE (2019) A new testate amoebae species Planhoogenraadia wuchanica sp. nov. from subtropical forest soils in Wuhan, central China Zootaxa, 4550: 289-294.

Bobrov, Anatoly, Qin, Yangmin, Payne, Richard J. (2019): ANATOLY BOBROV, YANGMIN QIN & RICHARD J. PAYNE (2019) A new testate amoebae species Planhoogenraadia wuchanica sp. nov. from subtropical forest soils in Wuhan, central China Zootaxa, 4550: 289-294. Zootaxa 4614 (3): 600-600, DOI: https://doi.org/10.11646/zootaxa.4614.3.1

A new testate amoebae species Planhoogenraadia wuchanica sp. nov. from subtropical forest soils in Wuhan, central China

Bobrov, Anatoly, Qin, Yangmin, Payne, Richard J. (2019): A new testate amoebae species Planhoogenraadia wuchanica sp. nov. from subtropical forest soils in Wuhan, central China. Zootaxa 4550 (2): 289-294, DOI: https://doi.org/10.11646/zootaxa.4550.2.

Fig. 1. SEM photos showing c.f in Latitudinal Diversity Gradients in Free-living Microorganisms - Hoogenraadia a Key Genus in Testate Amoebae Biogeography

Fig. 1. SEM photos showing c.f. Hoogenraadia humicola found from soils in Shennongjia Mountains of central China (the left picture is from Qin et al. 2011). This was previously identified as Planhoogenraadia africana by Qin et al. (2011). Scale bars: 50 µm (a) and 20 µm (b).Published as part of Bobrov, Anatoly, Qin, Yangmin & Wilkinson, David M., 2015, Latitudinal Diversity Gradients in Free-living Microorganisms - Hoogenraadia a Key Genus in Testate Amoebae Biogeography, pp. 1-8 in Acta Protozoologica 54 (1) on page 3, DOI: 10.4467/16890027AP.15.001.2188, http://zenodo.org/record/835684

Hoogenraadia

Records of Hoogenraadia in China There were two extant Hoogenraadia taxa previously recorded in China, H. cryptostoma and H. asiatica to which can be added our new record of an additional species of uncertain identity (Shen 1983, Wang and Min 1987, Qin et al. 2011). In addition, the fossil H. asiatica was found in the sediments from late Pleistocene and Holocene (Wang and Min 1987). The limited nature of testate amoebae records from modern China make impossible to be sure if this species still exists or if it has become extinct. The testate species illustrated in Fig. 1 is common in the soils of Shennongjia Mountains, and it is especially abundant in the soils near the Dajiuhu peatland. The occurrence of this species was briefly noted and illustrated in Qin et al. (2011) under the name Planhoogenraadia africana – here we provide full details of this finding. The size of the specimens are as follows (N = 17): shell length 115–155 µm, shell width 50–65 µm which is mid-range in size for this genus.This was identified as Planhoogenraadia africana by Qin et al. (2011) – who also implied that the genera Planhoogenraadia and Hoogenraadia may be synonymous. However, because of the shape of the ventral apature (compare with Fig. 2c) we do not believe this taxon to be Hoogenraadia africana but tentatively assign it to c.f. Hoogenraadia humicola. These new records clearly illustrate the current diffi- culties in assigning some specimens to an unambiguous morpho-species and suggest that there is more to learn about the occurrence of this genus in China and further work is obviously required. Molecular data would obviously be very useful in sorting out the current uncertainties about the status of these morphospecies.Published as part of Bobrov, Anatoly, Qin, Yangmin & Wilkinson, David M., 2015, Latitudinal Diversity Gradients in Free-living Microorganisms - Hoogenraadia a Key Genus in Testate Amoebae Biogeography, pp. 1-8 in Acta Protozoologica 54 (1) on page 2, DOI: 10.4467/16890027AP.15.001.2188, http://zenodo.org/record/835684

Planhoogenraadia wuchanica Bobrov & Qin & Payne 2019

Planhoogenraadia wuchanica Qin, 2019 (Figs. 1–2) Comparison with similar species. C ompared to species with similar morphology (P. bonetti and P. daurica) Planhogenraadia wuchanica differs by smaller size (Table 2). The ventral region of P. wuchanica is not as flat as other Planhoogenraadia species. The smaller shell length, narrower aperture and distinctive ‘cap’ structure make P. wuchanica morphologically distinct from the similar taxa P. acuta, P. alta and P. asturica. Many protists exhibit phenotypic plasticity which can lead to morphological variability that could be mistakenly assumed to represent taxonomic difference (Mulot et al. 2017). However, it is improbable that phenotypic plasticity is the case here. Diagnostic features such as the ‘cap’ are clearly-developed structures not present in other, related taxa, whereas phenotypic plasticity is typically associated with variability in properties such as length and volume (Ogden & Hedley 1980; Arrieira et al. 2016; Mulot et al. 2017). The coefficients of variation we identify are small, further suggesting that phenotypic plasticity is unlikely. It is overwhelmingly probable that Planhogenraadia wuchanica is a previously-unrecorded species.Published as part of Bobrov, Anatoly, Qin, Yangmin & Payne, Richard J., 2019, A new testate amoebae species Planhoogenraadia wuchanica sp. nov. from subtropical forest soils in Wuhan, central China, pp. 289-294 in Zootaxa 4550 (2) on page 291, DOI: 10.11646/zootaxa.4550.2.9, http://zenodo.org/record/262538

Latitudinal Diversity Gradients in Free-living Microorganisms – Hoogenraadia a Key Genus in Testate Amoebae Biogeography

The extent to which free-living microorganisms show cosmopolitan distributions has been a contentious aspect of microbial ecology over the last few decades. Testate amoebae are a group of free living protists that can provide important evidence for the nature of the biogeography of microorganisms because there are relatively good data on the distribution of their morpho-species (compared to many other microbial groups). Many testate amoebae appear to exhibit ubiquitous distributions, while some taxa have proven to be endemic to limited regions. The genus Hoogenraadia (Gauthier-Lièvre and Thomas 1958) is of particular interest in this context as it appears to be restricted to relatively low latitudes. There are six described species of the genus: H. africana Gauthier-Lièvre and Thomas 1958, H. asiatica Wang and Min 1987, H. cryptostoma Gauthier-Lièvre and Thomas 1958, H. humicola Bonnet 1976, H. ovata Bonnet 1976, and H. sylvatica Vucetich 1974. However, information on these taxa is scattered through a number of different papers – here we provide a summary of what is known about the taxonomy and ecology of this genus. We also reinterpret recent new records of putative H. africana from China (suggesting this identification is not reliable). As an example of a protist taxon largely restricted to the tropics this genus is of particular interest in microbial biogeography and this paper discusses its morphology, ecology and distribution in this context