TABLE 2 in Two new species of Achnanthidium Kützing (Achnanthidiaceae) from the Quaternary sediments of the Colônia basin, Southeast Brazil

TABLE 2. — Morphometric data from Achnanthidium craterianum Marquardt & C.E.Wetzel, sp. nov. populations found in the Colônia basin, São Paulo,Brazil, and the most similar taxa belonging to the A. minutissimum complex. ND, no data.
Achnanthidium craterianum A. sieminskae Witkowski,A. caledonicum (Lange-A. digitatum Pinseel,Marquardt & C.E.Wetzel, Kulikovskiy & Riaux-Bertalot) Lange-Vanormelingen,sp. nov.GobinBertalotHamilton & van de VijverReferencethis studyVan de Vijver & KopalováWojtal et al. (2011)Pinseel et al. (2017)(2014)Valve outlinelinear to linear-lanceolatelinear to narrowly linear-linear to linear-lanceolatelinear to slightly linear-with almost parallellanceolate with almostlanceolate with almostmarginsparallel to slightly convexparallel marginsmarginsValve apicessubcapitate to capitate,clearly protracted, rostratecapitateprotracted, (slightly)protracted and faced toto capitate apicessubrostrate to broadlyopposite directionsrounded, not protracted,in smaller specimensLength (µm)8.5-19.09.5-18.014.2-38.08.6-19.1Width (µm)2.0-2.51.9-3.12.3-3.21.8-2.3Girdle viewrectangular arched, withclearly bent around theNDrectangular archedpointed apices slightlytransapical axis and withcurvedclearly recurved apicesRaphe valveAxial areaaxial area narrow to faintlynarrow linearlinear, becoming weaklynarrow, linear, only slightlylanceolate towards thelanceolate towards thewidening towards centralcentral areacentral areaarea; almost absent nearthe apicesCentral areasmall, roundedelliptical to rounded, veryrhombicsmall, rounded or forming asmall, almost indistinctclear rectangular fasciaTerminal raphestraight, terminating afterweakly deflected,straight, terminating afterstraight, terminating afterfissuresthe last striaeterminating on the valvethe last striaethe last striaeface/mantle junctionStria density (in 10 µm)32-3332-3430-3531-36Areolae openingroundedround to slit-likeround, elongated or slit-rounded or broadlyliketransapically elongatedAreolae number2-32-32-42, rarely 3(at the center)Rapheless valveAxial areanarrow and linear to weaklynarrow and linearlinear, weakly lanceolatenarrow linear, slightlylanceolate towards thetowards the central area widening towards thecentral areacentral areaCentral areaabsent or narrowabsentabsentalmost non-existent, neverlanceolateforming a fascia orsubfasciaStria density (in 10 µm)40-4234-36ND31-36Areolae openingrounded to elongatedround to slit-likeround, elongated or slit-rounded or broadlyliketransapically elongatedAreolae number2-32-5ND2, rarely 3(at the center)