Emphanisporites? tenuis sp. nov, 1961

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 : 46

Emphanisporites? tenuis sp. nov .

Fig. 11K–N .

1981 Emphanisporites sp. D ; Richardson et al. 1981: 215, pl. 1.3.

2008 Emphanisporites sp. D Richardson, Rasul, and Al-Ameri, 1981; Steemans et al. 2008: 274, figs. 8–10.

2014 Emphanisporites sp. D Richardson et al. 1981; García Muro et al. 2014b: 485, fig. 8f.

2015 Emphanisporites sp. D Richardson et al. 1981; García Muro and Rubinstein 2015: 272, fig. 3.7.

Etymology: From Latin tenuis, tenuous; in references to the characteristic thin ribs.

Type material: Holotype: MPLP 13-60984 ( N30 /2) ( Fig. 11K ) . Paratype: MPLP 2-61065 ( Q42 ) ( Fig. 11L ) from Cerro La Chilca section .

Type locality: Quebrada Ancha upper section, Los Espejos Formation, San Juan, Argentina ( Fig. 1D , 4 ) .

Type horizon: Storm-dominated inner shelf environment of the Los Espejos Formation, Přídolí.

Material.— Seven specimens measured. Samples MPLP 1-61065 (O28/3); MPLP 2-61057 (O47/1; Q42/1, U27); MPLP 2-60704 (K38/4), MPLP 9-60664 (S28), MPLP 10-60673 (J23/1). Wenlock?–Přídolí of Argentina, Cerro La Chilca and Quebrada Ancha localities, Los Espejos Formation.

Diagnosis.—Trilete patinate spore with numerous tenuous ribs on the proximal face.

Description.—Trilete patinate spore with subtriangular to subcircular amb. The thickness of the patina is variable. Laesure straight, extends to the equator, accompanied by labra about 2–4 μm in overall width. Equatorially thickened, 2–4 μm wide. Proximally, 18–26 ribs of less than 1μm of width per interradial area, extending to the patina.

Dimensions.—42–(50)–55μm (7 specimens measured).

Remarks.—Other species of Emphanisporites differ in presenting broader radial ridges and having no patina. Artemopyra inconspicua Breuer, Al-Ghazi, Al-Ruwaili, Higgs, Steemans, and Wellman, 2007 is ornamented by similar thin radial ribs in the hilum but lacks the trilete mark and the patina. According to the original diagnosis of McGregor (1961), the genus Emphanisporites does not comprise patinate forms. Possibly, a new genus should be considered for the specimens included in Emphanisporites? tenuis although the specimens are not enough to create it in the present contribution.

Stratigraphic and geographic range.— Richardson et al. (1981) recorded Emphanisporites sp. D from the late Ludlow of Libya and the early Přídolí of England and Wales but did not describe the species and the latter was not even illustrated. Lochkovian of the Amazon Basin, Brazil ( Steemans et al. 2008). Wenlock? to Přídolí of the Precordillera, Argentina ( García Muro et al. 2014b; García Muro and Rubinstein 2015).

Figures

Fig. 11. Palynomorphs from the studied sections of the Los Espejos Formation of Argentina, Quebrada Ancha, Přídolí (A, F, K, M, N), Cerro La Chilca, Gorstian?–Ludfordian? (B, L), Quebrada Ancha, Ludfordian (C, E, H), Cerro La Chilca, Ludfordian (D, G, I, J). A. Tylotopalla caelamenicutis Loeblich, 1970; MPLP 14-60982 (E32/3). B. Tylotopalla deerlijkianum (Martin, 1973) Martin, 1978; MPLP 2-61057 (K42/2). C. Tylotopalla robustispinosa (Downie, 1959) Mullins, 2001; MPLP 2-60704 (L42/2). D. Veryhachium trispinosum Group Servais, Vecoli, Li, Molyneux, Raevskaya, and Rubinstein, 2007; MPLP 4-61059 (E33). E. Vestitusdyadus sp.; MPLP 8-60677 (G31/1). F. Villosacapsula setosapellicula (Loeblich, 1970) Loeblich and Tappan, 1976; MPLP 9-60664 (Q30). G. Villosacapsula sp.; MPLP 5-61060 (U32/2). H. Visbysphaera cf. pirifera (Eisenack, 1954) Kiryanov, 1978; MPLP 8-60677 (T33). I. Indeterminate palynomorphs; MPLP 4-61059 (G35/4) (I1, I2 are different focus). J. cf. Veryhachium sp., with abnormal processes, distally expanded; MPLP 4-61059 (P25/3). K–N. Emphanisporites? tenuis sp. nov. K. MPLP 13-60984 (N30/2). L. MPLP 2-61057 (Q42). M. MPLP 10- 60673 (J23). N. MPLP 12-60986 (R34). Scale bars 20 μm.

Fig. 1. A, B. Geographic location of study areas. C, D. Geologic maps showing the fossil localities (asterisks). The northern and middle (C) and southern D) part of the Silurian–Devonian Basin. 1, Río Jáchal; 2, Río de las Chacritas; 3, Cerro La Chilca (this paper); 4, Quebrada Ancha (this paper).

Fig. 4. Ludlow–Přídolí (424 My) phytoplankton and miospore assemblages plotted on a palaoegeographic reconstruction using BugPlate software (Torsvik 2009). 1, UK (Richardson and Lister 1969; Lister 1970; Richardson et al. 1981; Burgess and Richardson 1995; Wellman and Richardson 1996; Richards and Mullins 2003; Mullins 2001, 2004); 2, Gotland, Sweeden (Stricanne et al. 2004; Stricanne et al. 2006); 3, Allenport, USA (Beck and Strother 2008); 4, Nova Scotia, Canada (Beck and Strother 2001); 5, Ontario, Canada (McGregor and Camfield 1976); 6, Sweden (Mehlqvist et al. 2012; Mehlqvist et al. 2014); 7, Libya (Richardson and Ioannides 1973; Rubinstein and Steemans 2002; Le Hérissé 2002); 8, Saudia Arabia (Le Hérissé et al. 1995; Wellman et al. 2000; Breuer et al. 2017); 9, Poland (Porębska et al. 2004); 10, Turkey (Steemans et al. 1996; Lakova and Göncüoğlu 2005); 11, Iraq (Al-Almeri 1984; 2010); 12, Maranhão Basin, Brazil (Brito 1967); 13, Bolivia (Cramer et al. 1974; Kimyai 1983; Racheboeuf et al. 2012); 14, Spain and West France (Rodríguez González 1978; 1983; Steemans 1989; Cramer 1964a; Richardson et al. 2001); 15, Amazon Basin, Brazil (Cardoso 2005; Steemans et al. 2008); 16, Santiago del Estero, Argentina (Pöthe de Baldis 1974a); 17, Precordillera Argentina (Rubinstein 1992a, b, 1995; García Muro et al. 2014b; this contribution). References discussed in the papers are also included.