Chara artesica, Sanjuan & Martín-Closas, 2014

Sanjuan, Josep & Martín-Closas, Carles, 2014, Taxonomy and palaeobiogeography of charophytes from the Upper Eocene- Lower Oligocene of the Eastern Ebro Basin (Catalonia, NE Spain), Geodiversitas 36 (3), pp. 385-420 : 394-396

Chara artesica n. sp.

( Fig. 4 I-L)

DIAGNOSIS. — Very small gyrogonites of genus Chara , 329-455 µm high and 232-368 µm, ellipsoidal elongate in shape, with a reduced number of convolutions (generally seven) and concave spiral cells.

HOLOTYPE. — Number 79907 of the Museu Geològic del Seminari Conciliar, Barcelona ( Fig. 4 I-L).

PARATYPES. — Numbers 79908-79911 of the Museu Geològic del Seminari Conciliar, Barcelona.

TYPE LOCALITY. — Torre Casanova (Moià, Catalonia, NE Spain; 41°49’13, 6”N, 02°08’13, 2”E) .

TYPE STRATUM. — Marls of the Artés Formation, in a bed 45 m above the base of the Torre Casanova stratigraphic section (Sanjuan & Martín-Closas 2012: sample TC-9, fig. 7).

AGE. — Middle Priabonian to Lower Rupelian according to its association with H. vasiformis form vasiformistuberculata and Harrisichara tuberculata .

DERIVATION OF NAME. — From the Artés Formation.

REPOSITORY. — Museu Geològic del Seminari Conciliar, Barcelona (MGSCB).

DESCRIPTION

Gyrogonites small, 329-455 µm high (mean 397 µm) and 232-368 µm wide (mean 304 µm), prolate and elongate in shape, with an isopolarity index ranging from 109-157 (mean 129). Spiral cells concave to almost flat (about 48 µm wide) and without ornamentation. Six to nine (frequently seven) convolutions are visible in lateral view ( Fig. 5 ). Apex flat or slightly convex. Apical ends of cells unmodified or slightly widening in the centre. Base frequently pointed with a small pentagonal pore (about 45 µm in diameter). Wellcalcified gyrogonites show a rounded base.

AFFINITY

Ŋis new species belongs to genus Chara as shown by its ellipsoidal gyrogonite, the shape of the apical region, with slightly widening of spiral cell endings, and by the shape of the base, pointed to rounded with the spiral cell ends forming a superficial pentagonal pore. Ŋe combination of the very small size of the gyrogonites, a low number of convolutions and the concavity of the spiral cells allows the distinction of the new species from similar species. Chara artesica n. sp. shows strong similarities with Chara sp. 2 from the Ebro Basin described by Choi (1989), especially as regards their biometrical characters. However, Chara artesica n. sp. shows concave spiral cells and a flat to slightly convex apex, whereas Chara sp. 2 shows a convex shape in the apex and the spiral cells, probably related to the calcification degree.

Chara rhenana Schwarz & Griessemer, 1994 ( Fig. 4 M-P)

Chara rhenana Schwarz & Griessemer, 1994: 148 , pl. 1, figs 1-4.

DISTRIBUTION. — Previously, this species had only been reported in the Upper Eocene/Lower Oligocene from the Rhine Graben in Germany ( Schwarz & Griessemer 1994; Schwarz 1997). Ŋe occurrence of this species in Sant Boi de Lluçanès provides the first occurrence of this species in southern Europe ( Table 2 ).

DESCRIPTION

Medium-sized gyrogonites, 550-750 µm high (mean 640 µm) and 283-575 µm wide (mean 392 µm), very elongate, prolate to perprolate in shape, with a high isopolarity index ranging from 111-195 (mean 164). Concave to flat and nonornamented spiral cells (61 µm wide). Eight to eleven (frequently nine to ten) convolutions visible in lateral view. Apex flat. Apical ends of spiral cells distinctly widened. Base progressively tapering to pointed. Many specimens show a somewhat conical appearance. Basal pore mainly within a shallow pentagonal depression.

REMARKS

Most specimens of Chara rhenana from El Perers (Sant Boi de Lluçanès, NE Ebro Basin) are about 100 µm longer than the type population from the Rhine Graben ( Schwarz & Griessemer 1994). Ŋe specimens studied are also similar to Chara vespiformis Groves, 1926 from the Bembridge flora (Isle of Wight, England). However, Chara vespiformis shows more convolutions in lateral view (twelve to thirteen) and the spiral cells are flat or convex.

Chara microcera Grambast & Paul, 1965 ( Fig. 6 A-D)

Chara microcera Grambast & Paul, 1965: 244 , pl. 2, figs 10-14.

DISTRIBUTION. — Chara microcera has been recorded from numerous localities in Europe ranging in age from the Lower Oligocene (Middle Rupelian) to Lower Miocene (Upper Aquitanian). In France, this species occurs in the Paris Basin ( Grambast & Paul 1965; Riveline 1986), the Aquitaine Basin (Feist-Castel 1977a; Feist & Ringeade 1977) and the Provence Basin (Feist-Castel 1977a). In Switzerland, this species has been recorded in the western sector of the Swiss Molasse Basin ( Kissling 1974). Ŋis species also occurs in many Oligocene localities from the Rhine Graben in Germany ( Schwarz 1997). In Spain, this species has been reported in Lower Oligocene beds of the Ebro Basin ( Feist et al. 1994), and in the Tajo Basin ( Juliá de Agar 1991). In this study, Chara microcera is reported from lacustrine marls in the El Talladell and Vinaixa localities (NE Ebro Basin) (Table 4).

DESCRIPTION

Small-sized gyrogonites, 366-500 µm high (mean 440 µm) and 280-360 µm wide (mean 320 µm), elongate, prolate to perprolate in shape, with an isopolarity index ranging from 120-160 (mean 129). Concave spiral cells (42 µm wide) ornamented with characteristic isolated tubercles arranged along the spiral cells. Nine to eleven (frequently nine) convolutions visible in lateral view. Apex psilocharoid, flat and slightly prominent, ornamented with isolated small tubercles. Base rounded to slightly pointed showing a shallow pentagonal basal pore.

Figures

FIG. 4. — Charophytes from the Sant Boi and Artés Fms, Ebro Basin:A-D, Sphaerochara labellata Feist & Ringeade, 1977, Torre Casanova section; A, apical view, no. 80063 MGSCB, sample TC-28; B, lateral view, no. 80064 MGSCB, sample TC-28; C, lateral view, no. 80065 MGSCB, sample TC-28; D, basal view, no. 80066 MGSCB, sample TC-28; E-H, Chara aff. antennata Grambast, 1958, La Portelleta section; E, apical view, no. 80067 MGSCB, sample PO-2; F, lateral view, no. 80068 MGSCB, sample PO-2; G, lateral view, no. 80069 MGSCB, sample PO-2; H, basal view,no. 80070 MGSCB, sample PO-2; I-L, Chara artesica n. sp., Torre Casanova section; I, apical view, paratype no. 79908 MGSCB, sample TC-9; J, lateral view, holotype no. 79907 MGSCB sample TC-9; K, lateral view, paratype no. 79909 MGSCB, sample TC-9; L, basal view, paratype no. 79910 MGSCB,sample TC-9; M-P, Chara rhenana Schwarz & Griessemer,1994,El Perers-Serrat Rodó section;M, apical view, no. 80071 MGSCB,sample PE-1; N, lateral view,no. 80072 MGSCB, sample PE-1; O, lateral view, no. 80073 MGSCB, sample PE-1; P, basal view, no. 80074 MGSCB, sample PE-1. Scale bar: 500 µm.

FIG. 5. — Frequency distribution of the length, width, number of convolutions, length/width ratio (ISI) and dispersion graphic of three populations (50 gyrogonites per population) of Chara artesica n. sp. Populations from samples CC-1 (El Perers-Serrat Rodó section) SMO-5 (Santa Maria d’Oló section) and Mo-1 (Moià section).

FIG. 6. — Charophytes from Sant Boi, Artés and lateral south-western Formations,Ebro Basin:A-D, Chara microcera Grambast & Paul, 1965, El Talladell outcrop; A, apical view, no. 80075 MGSCB, sample BO-2; B, lateral view, no. 80076 MGSCB, sample BO-2; C, lateral view, no. 80077 MGSCB, sample BO-2; D, basal view, no. 80078 MGSCB, sample BO-2; E-H, Psilochara aff. acuta Grambast & Paul, 1965, Sarral section; E,apical view, no. 80079 MGSCB,sample SA-2;F, lateral view, no. 80080 MGSCB,sample SA-2;G, lateral view, no. 80081 MGSCB, sample SA-2; H, basal view, no. 80082 MGSCB, sample SA-2; I-L, Lamprothamnium sp. El Perers-Serrat Rodó section (Cal Carreter locality); I, apical view, no. 80083 MGSCB, sample CC-1; J, lateral view, no. 80083 MGSCB, sample CC-1; K, lateral view, no. 80084 MGSCB, sample CC-1; L, basal view, no. 80085 MGSCB, sample CC-1. Scale bar: 500 µm.