taxonID	type	description	language	source
03F72A42FFB4B527618639BD20A4FD71.taxon	description	Description — LM (Figs 1 – 40): Frustules are usually solitary, girdle view rectangular, slightly arched, with apices slightly recurved to the rapheless valve (Figs 38 – 40). Valve are linear-elliptic to linear-lanceolate to lanceolate, with broadly round to sub-rostrate ends (Figs 1 – 37); 17.0 – 20.0 μm long and 3.0 – 4.0 μm wide (n = 40). Striae not discernible, except in the middle part of the valve where a few separated slightly radiated striae (2 – 5) become resolvable due to a wider spacing (Figs 1 – 37). Raphe valve (Figs 1 – 29): Raphe filiform straight. Axial area linear-lanceolate, expanding to a small apically a linear-elliptic central area located between the proximal raphe ends (Figs 1 – 29). Rapheless valve (Figs 30 – 37): slightly convex with a narrow and linear axial area (Figs 31, 35, and 36), sometimes expanding to a small, elliptic central area (Figs 30, 32, and 34). SEM (Figs 41 - 49): Raphe valve slightly concave (Figs 48 – 49). The rapheless valve slightly convex (Figs 48 – 49). Distal raphe ends terminating after the last stria at the mantle (Fig. 41). Central and terminal raphe fissures straight (Fig. 41). Striae uniseriate, radiate throughout, 30 – 35 in 10 μm, composed of 3 – 4 rounded areolae (Figs 41 – 47), sometimes with slit-like areolae near the valve margin (Figs 41 – 47). Externally, axial area narrowly linear and silicified, widening towards the central area (Fig. 41). Internally, proximal raphe ends slightly curved in opposite directions (Figs 42 – 44), and distal raphe ends terminate as helictoglossae (Fig 42 – 43). Areolae occluded with fine a hymen (Fig. 44). The mantle has one row of slit-like areolae (Figs 48 – 49). Type: BRAZIL. State of São Paulo: Guarulhos, phytoplankton from Negro Lake, 23 ° 18 ’ 20 ” S, 46 ° 23 ’ 26 ” W, 1500 m, 1 June 2020, Collector (s): João S. Osti, Edna Ferreira & Gisele C. Marquardt. (holotype here designated, permanent slide: UPCB 105117, Universidade Federal do Paraná, Brazil, UPCB). Etymology: The specific epithet refers to the type locality, city of Guarulhos. Ecology and associated diatom flora: The new species is associated, among others, with Ulnaria delicatissima var. angustissima (Grunow) Aboal & P. C. Silva (2004: 361), Ulnaria ulna (Nitzsch) Compère (2001: 100), Achnanthidium sp., Aulacoseira ambigua (Grunow) Simonsen (1979: 56), and Spicaticribra rudis (Tremarin, T. Ludwig, V. Becker & Torgan) in A. Tuji, Leelahakriengkrai & Peerapornpisal (2012: 146). We cannot confirm whether Achnanthidium guarulhense sp. nov. is a planktic diatom species since no other substratum (periphytic or benthic material) was sampled. Achnanthidium guarulhense sp. nov. was recorded in the phytoplankton community of a shallow lake with soil walls and bottom during the spring. The taxon was found representing 20 % of the phytoplankton community. Cyanobacteria, Chlorophyceae, and Trebouxiphyceae were the most abundant classes of the community and contributed 33 %, 18 %, and 15 %, respectively, of the relative abundance. The following limnological features were presented at the time of the sample: water temperature 19.17 ºC, pH 6.17, electrical conductivity 72.37 μS. cm- 1, dissolved oxygen 8.67 mg. L- 1, turbidity 10.00 NTU, and Secchi transparency 1.85 m. According to the trophic state index, Negro Lake is described as an oligo-mesotrophic system (Osti et al. 2022).	en	Silva, Mariana B. A., Osti, João A. S., Bicudo, Denise C., Marquardt, Gisele C. (2024): Achnanthidium guarulhense sp. nov. (Achnanthidiaceae, Bacillariophyta), a new diatom species from a Conservation Unit in Southeast Brazil. Phytotaxa 640 (3): 275-283, DOI: 10.11646/phytotaxa.640.3.5, URL: http://dx.doi.org/10.11646/phytotaxa.640.3.5
