Chara sp.

Sanjuan, Josep & Alqudah, Mohammad, 2018, Charophyte flora from the Miocene of Zahle (Beeka Valley, Lebanon). Biostratigraphic, palaeoenvironmental and palaeobiogeographical implications, Geodiversitas 40 (10), pp. 195-209 : 201-203

Chara sp.

( Fig. 3 I-K)

MATERIAL EXAMINED. — 10 well-preserved gyrogonites have been recovered from sample Zahle 1.

DESCRIPTION Small to medium sized gyrogonites, 486-637 µm high (mean 555 µm) and 375-456µm wide (mean 416µm), elongate and prolate in shape, with an isopolarity index ranging from 120 to 144 (mean 130). Nine to eleven convolutions are visible in lateral view in mean value). Spiral cells flat to concave, about 54 µm wide and without ornamentation. Apex psilocharoid and prominent. Base rounded to slightly pointed showing a small pentagonal basal pore.

REMARKS

This population from Zahle 1 belongs to the genus Chara , although the reduced number of specimens found hinders at present their specific attribution.

Genus Lychnothamnus (Ruprecht, 1845) Leonhardi, 1863 emend. A. Braun in Braun & Nordstedt (1882) Lychnothamnus barbatus (Meyen, 1827) Leonhardi, 1863

Lychnothamnus barbatus var. antiquus Soulié-Märsche, 1989 ( Figs 5 ; 6 )

Lychnothamnus barbatus var. antiquus Soulié-Märsche, 1989: 155 , pl. XXXVII, figs 1-6.

MATERIAL EXAMINED. — 40 well-preserved gyrogonites have been recovered from sample Zahle 2.

DESCRIPTION

Gyrogonites large, very variable in size, 619-901µm high (mean 773 µm) and 521-739 µm wide (mean 613 µm), ellipsoidal in shape with an isopolarity index ranging from 108 to 144 (average 125). Spiral cells in the apical zone show a remarkably constant width, which results in a flat apex ( Fig. 5A, B ). The base is tapered with a star-shaped basal pore, about 80 µm in diameter ( Fig. 5C ). Nine to eleven (frequently ten) cells visible laterally ( Fig. 5 D-H). These are normally concave ranging from 62 to 115 µm in height (mean 84 µm), nonornamented and separated by prominent sutures, sometime bicarinated ( Fig. 5D ).

BIOSTRATIGRAPHY

This species is known from the Miocene in Europe and extends through the Pliocene up to recent times (Soulié- Märshe 1989).

PALAEOECOLOGY

Inferred through comparison with the ecological requirements of its single living representative Lychnothamnus barbatus (check the chapter charophyte palaeoecology).

DISTRIBUTION

Lychnothamnus barbatus var. antiquus has hitherto been recorded from numerous Miocene European localities i.e., Spain (González-Pardos 2012; Suárez-Hernando et al. 2013), southern France (Soulié-Märsche 1989), Portugal (Antunes et al. 1992), Montenegro ( Krstić et al. 2010) and Turkey (Mazzini et al. 2013). The extant representative i.e., L. barbatus is a common species of the moraine lakes of Northern Europe ( Karczmarz 1967). It was formerly known from Germany, Poland, France, Italy and Austria (Migula 1897; Corillion 1972; Krause 1986). Lychnothamnus barbatus has been also recorded in the Balkans area ( Blaženčić et al. 2006), Poland (Sugier et al. 2010) and Ukrainia ( Borisova & Yakushenko 2008). This species has been rarely found growing in other areas out of Europe such as Asia ( Gollerbakh & Krasavina 1983), Australia ( Casanova et al. 2003) and North America ( Karol et al. 2017).

Figures

FIG. 3. — Charophytes from the lacustrine deposits of Zahle, sample Zahle 1: A-H, Chara aff. microcera Grambast & Paul, 1965; A, lateral view, no. 2017001 AUBGM; B, lateral view, no. 2017002 AUBGM; C, lateral view, no. 2017003 AUBGM; D, lateral view, no. 2017004 AUBGM; E, apical view, no. 2017004 AUBGM; F, apical view, no. 2017002 AUBGM; G, basal view, no. 2017005 AUBGM; H, basal view, no. 2017006 AUBGM; I-K, Chara sp; I, apical view, no. 2017007 AUB- GM; J, lateral view, no. 2017008 AUBGM; K, basal view, no. 2017009 AUBGM. Scale bar: 200 μm.

FIG. 5. — Charophytes from the lacustrine deposits of Zahle, sample Zahle 2: A-H, Lychnothamnus barbatus var. antiquus Soulié-Märsche, 1989; A, apical view, no.2017010 AUBGM;B, apical view,no.2017011 AUBGM;C, basal view,no. 2017012 AUBGM;D, lateral view,no.2017013 AUBGM;E, lateral view,no. 2017014 AUBGM; F, lateral view, no. 2017015 AUBGM; G, lateral view, no. 2017016 AUBGM; H, lateral view, no. 2017017 AUBGM. Scale bar: 500 μm.

FIG. 6. — Biometric values of Lychnothamnus barbatus var. antiquus Soulié-Märsche, 1989 from sample Zahle 2 (n = 40 gyrogonites): A, gyrogonite height (µm); B, gyrogonite width (µm); C, number of convolutions visible in lateral view; D, isopolarity index (ISI = h/w × 100).