Late Silurian palynomorphs from the Precordillera of San Juan, Argentina: Diversity, palaeoenvironmental and palaeogeographic significance Author García Muro, Victoria J. Author Rubinstein, Claudia V. Author Steemans, Philippe text Acta Palaeontologica Polonica 2018 2018-01-11 63 1 41 61 http://dx.doi.org/10.4202/app.00400.2017 journal article 294456 10.4202/app.00400.2017 1f3b033c-0992-4bf0-9a03-516843ea8a52 1732-2421 10626537 cf. Melikeriopalla sp. Fig. 9A–F . Material.— 14 specimens measured. Samples MPLP 1-61065 ( U47 /2, W30 /3); MPLP 3-61058 ( L33 ); MPLP 6-61061 ( M31 /3); MPLP 7-61062 (D39, D45/3, P43 /3, P50 /3); MPLP 2-60704 ( L26 /4); MPLP 3-60659 ( F38 /3, R38 /1); MPLP 4-62521 ( T40 /4, T40 /4); MPLP 6-60662 ( J25 /2). Vesicle divided into filds by muri. Homerian–Ludfordian of Argentina . Cerro La Chilca and Quebrada Ancha localities, Los Espejos Formation . Description.— Vesicle square to sub-spherical, divided into 6–13 polygonal fields by thick muri. Each field is ornamented by a ring and/or a granum; when both are present the granum is located in the center of the ring. Dimensions.— Vesicle 16–(23)–30 μm, fields 6–(9)–12 μm, muri high 0.3–1 μm, grana high 0.5–(1)–3 μm, grana diameter 1–(3)–5 μm, rings high 0.3–(0.5)–1 μm, rings thick 0.5–(1.5)–3 μm (14 specimens measured; number in brackets is the mean value). Discussion.— According to the emended diagnosis of Mullins 2001 ), in the centre of each field a circular node beneath which a pore may or may not be present. Because of the poor preservation, the pore cannot be observed in the specimens from the Los Espejos Formation. The genus was assigned with doubts because no ring was described for Melikeriopalla .