Table 1. Comparison of Pseudostaurosira aedes sp. nov., P. pulchra sp. nov and P. sajamaensis with other Pseudostaurosira and Pseudostaurosiropsis taxa of similar valve outline. Features in bold italic font are defining for each taxon. Feature/speciesPseudostaurosira aedes sp. nov.P. altiplanensis (Lange-Bertalot & Rumrich) E. MoralesP. pulchra sp. nov.P. sajamaensis E. Morales & EctorPseudostaurosiropsis connecticutensis E. MoralesP. geocollegarum (Witkowski) E. MoralesValve dimensions (µm)L: 2.9-12.3 W: 2.1-2.6L: 4.5-8.0 W: 2.8-3.6L: 5.0-22.0 W: 2.4-3.0L: 2-18 W: 2-4L: 1.9-13.5 W: 1.5-4.7L: 5-16 W: 2-4Stria density (in 10 µm)1514-1513-1610-1417-2012-16Valve outline; axial area; virgaeNarrowly elliptic with rounded ends with abrupt transition of valve face to mantle; narrowly lanceolate; wide and slightly raised with respect to axial area, both elevated in internal viewBroadly elliptic with abrupt transition of valve face to mantle; linear to narrowly lanceolate; wide and slightly raised together with axial area in both external and internal viewsNarrowly lanceolate with rostrate to broadly rounded ends with abrupt transition of valve face to mantle; narrowly lanceolate; wide and raised with respect to axial area in external and internal viewNarrowly elliptic in smaller specimens to elliptic with pointy ends in larger valves, with gradual transition from valve face to mantle; widely lanceolate; wide and raised with respect to virgae in external view, both elevated in internal viewRound to narrowly elliptic; broadly elliptic; wide, at the same level of axial area in external view, slightly raised in internal viewLanceolate with subrostrate ends; widely lanceolate; wide, raised with respect to axial area in external view, at the same level as axial area in internal viewAreolae; volae; striaeNarrow, elliptic to trapezoid; well-developed forming a tight mesh-like structure visible externally and internally; with 2, rarely 3 areolae, usually larger on valve mantleWide, often transapically elongated; well-developed forming a loose mesh-like structure visible externally and internally; with 2 or more areolae of ca. the same size change away from the valve face/mantle junctionNarrow, round to elliptic; well-developed forming a loose mesh-like structure visible externally and internally; typically composed by 2 areolae, usually larger on valve mantleVery wide, round to trapezoid on valve face, trapezoid to elongate on mantle; well-developed, forming a tight mesh-like structure as seen in internal view; usually composed of 2 areolae, wider ones on mantle, additional smaller ones more often seen on mantleNarrow, round, of about the same size on valve face and mantle; absent, rotae present; typically composed of 2 areolae of similar size, additional areolae more frequent on mantleNarrow, round, of about the same size on valve face and mantle; absent, rotae present; typically composed of 2 areolae of similar size, additional areolae more frequent on mantleSpines; stipules; flapsSolid, with elliptic to rectangular base, as wide as basal vimen, conical body, with a somewhat triangular profile, with serrate and pointy tips; well-developed, giving spines an arrowhead-like posterior profile; well-developed, disk-like or bilobate on valve face, smaller, usually more than 2 on mantleSolid, with elliptic base, narrower than basal vimen, cylindrical body with straight sides, spatulate tips with small and thin lateral projections; very little developed; incipient or little developedSolid, round to elliptic base, wider than basal vimen, flattened body with concave sides, straightly cut or slightly bifurcate apices; absent; well-developed, circular on valve face, smaller, usually more than 2 on mantleSolid, heavily silicified with elliptic base as wide as basal vimen, flattened body, sometimes with a V-shaped cleft in its posterior side, with diapason-shaped tips with serrate borders and pointy, downward, lateral projections; well-developed, giving the spine a sagittate lateral profile; well-developed, bilobate on valve face, less developed on mantleHollow, with elliptic base as wide as basal vimen, flattened, biconcave-spatulate body with bifurcate ends; absent; absentHollow, round to elliptic base as wide as vimen, pyramidal as the body starts, becoming cylindrical toward the top, with bifurcate ends; absent; absentApical pore fields; mantle abvalvar blistersPresent and very reduced, usually no more than 3 round poroids, opening in a single linear depression in internal view; well-developed, covering the apical pore fieldsPresent or absent, composed of up to 3 rows of round poroids opening into a single, roundish internal depression; small, covering the apical pore fieldsAbsent, well-developed, covering the apicesAbsent or reduced, composed of a single row of round poroids opening in a single roundish depression in internal view; developed, present at apices but not covering the apical pore fieldsPresent or reduced, with small round poroids opening into a single roundish depression in internal view; small, present at apices but not covering apical pore fieldsComposed of up to three cavernous poroids, opening as large pores at the valve interior; small, present at apices but not covering apical pore fieldsReferencesThis studyRumrich et al. (2000), Seeligmann et al. (2018)This studyMorales et al. (2012b), This studyMorales (2001), Beauger et al. 2019)Morales (2001, 2002), Beauger et al. (2019), Radhakrishnan et al. (2020)

Published as part of 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, pp. 23 in PhytoKeys 187 on page 23, DOI: 10.3897/phytokeys.187.73338