Hydrurus foetidus (Villars) Trevisan (Wei, 2018

Hao, Junxue, An, Yalu, Nan, Fangru, Lv, Junping, Liu, Qi, Liu, Xudong, Xie, Shulian & Feng, Jia, 2024, New molecular evidence of the genus Hydrurus (Chrysophyceae) and descriptions of Hydrurus foetidus (Villars) Trevisan on the basis of morphology and phylogeny, Biodiversity Data Journal 12, pp. e 137389-e 137389 : e137389-

Hydrurus foetidus

Materials

Type status: Other material. Occurrence: catalogNumber: SXU-SX 230328 ; recordedBy: Liu En-Hui; occurrenceID: B584ADE9-8946-54F2-B493-004E12833296; Taxon: scientificName: Hydrurus foetidus ; Location: locality: the Fenhe River, Shanxi Rrov., China ; verbatimElevation: 1869.2 m; verbatimCoordinates: 38.8574 N 112.0831 E; Identification: identifiedBy: Hao Jun-Xue; Event: year: 2023; month: 3; Record Level: type: specimen; language: en; collectionCode: Algae

Type status: Other material. Occurrence: catalogNumber: SXU-SX 230329 ; recordedBy: Liu En-Hui; occurrenceID: F1507A28-C087-5D3F-9053-42379E517331; Taxon: scientificName: Hydrurus foetidus ; Location: locality: the Fenhe River, Shanxi Rrov., China ; verbatimElevation: 1506.89 m; verbatimCoordinates: 38.6605 N 112.1085 E; Identification: identifiedBy: Hao Jun-Xue; Event: year: 2023; month: 3; Record Level: type: specimen; language: en; collectionCode: Algae

Type status: Other material. Occurrence: catalogNumber: SXU-SX 230330 ; recordedBy: Liu En-Hui; occurrenceID: 860CA1A8-0FA5-58A3-B5BD-E9EDC98518C9; Taxon: scientificName: Hydrurus foetidus ; Location: locality: the Fenhe River, Shanxi Rrov., China ; verbatimElevation: 1497.4 m; verbatimCoordinates: 38.5541 N 112.0191 E; Identification: identifiedBy: Hao Jun-Xue; Event: year: 2023; month: 3; Record Level: type: specimen; language: en; collectionCode: Algae

Type status: Other material. Occurrence: catalogNumber: SXU-SX 230331 ; recordedBy: Liu En-Hui; occurrenceID: 5677613E-26D2-51C6-A14B-4A62A0A4A514; Taxon: scientificName: Hydrurus foetidus ; Location: locality: the Fenhe River, Shanxi Rrov., China ; verbatimElevation: 1356.05 m; verbatimCoordinates: 38.3588 N 111.9287 E; Identification: identifiedBy: Hao Jun-Xue; Event: year: 2023; month: 3; Record Level: type: specimen; language: en; collectionCode: Algae

Description

The morphological characters of the specimen are shown in Figs 2 , 3 . The Hydrurus thalli, ranging from green to dark brown, were securely attached to the surface of stones, see Fig. 2 a and c. The thalli collected in Shanxi were approximately 5 cm in length. The thalli partially fragmented due to river erosion. Each thallus consisted of a firm central axis and peripheral branches, encased in a viscous gelatinous coating. Macroscopic views of the specimen are depicted in Fig. 2 b and d and microscopic details of specimens in Shanxi are shown in Fig. 3 .

The dimensions of different cells of specimens in Shanxi were measured. The apical cells of branches, 6.00–17.14 μm × 4.52–13.57 μm, were half spheroid with flat or angular (Fig. 3 c-e). The central axis cells were ellipsoid to ovoid and were 7.14–17.85 μm × 4.28–9.28 μm in size (Fig. 3 j and k). The branch cells were 5.88–19.99 μm × 4.41–9.34 μm (Fig. 3 f – i). The branch cells were further categorised into dense branching intercalary cells and loose branching free cells. The intercalary cells of the dense branches were ellipsoid with angular or compressed shapes, while the free cells of the loose branches were spherical to spheroid.

Distribution

The Fenhe River is the second largest tributary of the Yellow River, flowing through six cities in Shanxi Province. Hydrurus foetidus was collected in the Xinzhou section of this river. The physical and chemical parameters of water at four sites along the Fenhe River were recorded in Table 2 and the results revealed the following: the sites where H. foetidus was found ranged in altitude from 1356.05 to 1869.2 m, the water temperature ranged from 4.3 ℃ to 9.8 ℃, the pH ranged from 7.04 to 7.24. The lowest total dissolved solids content was 279.5 ppm, while the highest was 604.5 ppm. The dissolved oxygen concentration peaked at 15.22 mg / l, while the lowest was 12.27 mg / l. The electrical conductivity was lowest at 429.9 μS / cm, with other sites exhibiting values around 900 μS / cm. During our visit, the watercourse of the Fenhe River was observed to be between 70 and 200 cm deep. Notably, the Secchi depth of water at the source of the Fenhe River was 200 cm, significantly deeper than the 70–80 cm depths recorded at the other three sites. Total nitrogen levels ranged from 1.165 mg / l to 2.225 mg / l and total phosphorus levels were between 0.025 mg / l and 0.055 mg / l. COD varied between 41 mg / l and 50 mg / l and ammonium levels ranged from 0.35 mg / l to 0.47 mg / l.

Figures

Figure 2. Habitat and habitus of H. foetidus. a Habitat in the Fenhe River in March 2023; b Colony of H. foetidus collected from Shanxi growing on a stone surface, the dark green surface of the stone indicating colonies, shown by the arrow; c, d Macroscopic morphology of H. foetidus collected from Shanxi.

Figure 3. Morphological structures of Hydrurus foetidus collected from Shanxi, China observed by light microscope (LM). a, b arbuscular thalli of H. foetidus; c-e Larger magnifications of the distal part of thalli; f-h Intercalary cells of dense branches, cell division was happening in h; i free cells of loose branches and the polysaccharide sheath were visible; j, k Central axis cells; l newly-generated apical cells. Scare bars: a, b = 200 μm, c – l = 20 μm.