Pseudostaurosira frankenae E. Morales, C.E. Wetzel & Ector, 2021

Morales, Eduardo A., Wetzel, Carlos E. & Ector, Luc, 2021, New and poorly known " araphid " diatom species (Bacillariophyta) from regions near Lake Titicaca, South America and a discussion on the continued use of morphological characters in " araphid " diatom taxonomy, PhytoKeys 187, pp. 23-70 : 23

Pseudostaurosira frankenae E. Morales, C.E. Wetzel & Ector sp. nov.

Figs 6E-I (LM), 8A-F (SEM)

Holotype.

Slide ANSP GC 26815, Fig. 6E , Diatom Herbarium, Academy of Natural Sciences, Philadelphia (ANSP). Isotype. Slide DBOL-0246a, Diatomotheca Boliviensis (before HCUCB), Cochabamba, Bolivia.

Type locality.

Bolivia. Sajama Province, Department of Oruro, Desaguadero River, epipsammon, 17°23'51"S; 68°14'33"W, 3701 m elev., leg. G. Chávez, 05.07.2009.

Description.

Frustules rectangular with a curved middle portion in girdle view, joined together by interlocking spines. Valves cruciform, isopolar, with abrupt transition from valve face to mantle. Broadly rounded valve ends (Fig. 6E-I ). Axial area lanceolate with a broad central inflation (Fig. 6E-I ), externally and internally depressed with respect to virgae (Fig. 8A-C ). Vimines short and wide (Fig. 8A, B, E, F ). Striae typically composed round to elliptic areolae, decreasing in size towards the axial area (Fig. 8A, B ); a single elliptical areola present on valve mantle (Fig. 8A-C, E, F ). Well-developed volae, arising from the areolar inner periphery and projecting inwards (not shown here). Internally, depositions on volae forming round to elliptic structures, sealing areolae (Fig. 8C, D ). Flaps persistent, a single disk-like one covering each areola in external view (Fig. 8A, B, E, F ), 1-3 in enlarged mantle areolae (Fig. 8C ). Spines originating from vimines at the valve face/mantle junction; solid, with round to elliptical base (Fig. 8E ), wider that the vimines they sit on (Fig. 8F ); flattened, with shallow biconcave sides, triangular in side view (Fig. 8A, B, E, F ), and with spatulate body, bifurcate at the top (Fig. 8C ). Stipules absent. Apical pore fields of cavernous appearance in external view, occluded by heavy silica deposition to the point only one row of pores can be seen (Fig. 8A, B, E, F ). Internally, apical pore field opening into roundish depression, revealing several rows of round poroids (Fig. 8C, D ). Well-developed blister-like depositions present on abvalvar edge of mantle also covering both apices (Fig. 8A-C, D-F ). Girdle elements variable in number, open, lacking pores, ligulated, with larger valvocopula (Fig. 8A, B, F ).

Dimensions (n> 30): Length 8.7-12.0 μm; width 6.7-7.7 μm; striae 14 in 10 μm.

Etymology.

The species is dedicated to the late Dr. Margot Franken, Professor and Researcher from the Ecology Institute, University Mayor de San Andrés, La Paz, Bolivia. Dr. Franken, originally from Germany, worked in Bolivia from 1985 to 2021, focusing on bioindication, urban ecology, water management and ecological architecture.

Distribution.

Found only in the Desaguadero River.

Figures

Figure 6. A-V LM images of little known and new " araphid " diatoms from the Bolivian Altiplano A-D Pseudostaurosira vulpina stat. nov. E-I P. frankenae sp. nov. (Fig. 6 E is the holotype) J-O P. occulta sp. nov. (Fig. 6 K corresponds to the holotype) P-V P. oblonga sp. nov. (Fig. 6 R corresponds to the holotype). Scale bar: 10 µm.

Figure 8. A-F SEM images of Pseudostaurosira frankenae sp. nov. A, B titled frustules showing external features; notice open girdle elements in B (white arrows) C, D internal view of valves showing internal elliptic depositions on striae (dashed arrows) and depression of the apical pore field (black arrows) E close-up of frustule apex (B) showing the externally occluded apical pore field, showing only a single row of poroids (black arrow) F close-up of frustule tip (A) showing open girdle bands (white arrow). Scale bars: 2 µm (E, F); 3 µm (C); 5 µm (A, B, D).