Melikeriopalla sp.

García Muro, Victoria J., Rubinstein, Claudia V. & Steemans, Philippe, 2018, Late Silurian palynomorphs from the Precordillera of San Juan, Argentina: Diversity, palaeoenvironmental and palaeogeographic significance, Acta Palaeontologica Polonica 63 (1), pp. 41-61 : 45-46

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 .

Figures

Fig. 9. Palynomorphs from the studied sections of the Los Espejos Formation of Argentina, Cerro La Chilca, Homerian? (A, L), Cerro La Chilca, Gorstian?–Ludfordian? (B, I), Cerro La Chilca, Ludfordian (C, H, O, Q, T), Quebrada Ancha, Ludfordian (D–G, J, N, P, R, S), Quebrada Ancha, Přídolí (K, U), Quebrada Ancha, Gorstian?–Ludfordian? (M). A–F. cf. Melikeriopalla sp. A. MPLP 1-61065 (W30/3). B. MPLP 3-61058 (L33). C. MPLP 7-61062 (P43/3). D. MPLP 2-60704 (L26). E. MPLP 3-60659 (F38). F. MPLP 4-62521 (T40/4). G. Multiplicisphaeridium arbusculum forma A of Mullins (2001); MPLP 7-60736 (D30/1). H. Multiplicisphaeridium cladum (Downie, 1963) Eisenack, 1969; MPLP 4-61059 (E50/1). I. Multiplicisphaeridium mingusi Le Hérissé, 1989; MPLP 2-61057 (M31/1). J. Multiplicisphaeridium monki Le Hérissé, 1989; MPLP 3-60659 (O45/2). K. Multiplicisphaeridium rochesterensis Cramer and Diez, 1972; MPLP 9-60664 (U27). L. Nanocyclopia sp.; MPLP 1-61065 (U38/1). M. Neoveryhachium carminae (Cramer, 1964a) Cramer, 1970; MPLP 1-60667 (P45/2). N. Onondagella asymmetrica (Deunff, 1961) Playford, 1977; MPLP 7-60736 (X44). O. cf. Oppilatala frondis (Cramer and Díez, 1972) Dorning, 1981; MPLP 4-61059 (F45). P. Oppilatala grahni Le Hérissé, 1989; MPLP 7-60736 (E38/1). Q. Oppilatala insolita (Cramer and Díez, 1972) Dorning, 1981; MPLP 4-61059 (Q50). R. Oppilatala ramusculosa (Deflandre, 1945) Dorning, 1981; MPLP 7-60736 (N37/4). S. Ozotobrachion palidodigitatus (Cramer, 1966b) Playford, 1977; MPLP 7-60736 (P48/4). T. Percultisphaera incompta Richards and Mullins, 2003; MPLP 4-61059 (W47/4). U. Polyedrixium? cf. embudum Cramer, 1964a; MPLP 9-60664 (D39/1). Scale bars 20 μm.