Acrolejeunea ucrainica

Name

Acrolejeunea ucrainica

Rank

Species

Generic Name

[Genus] Acrolejeunea

Authors (Name)

Mamontov Yu. S. Heinrichs J. Schäfer-Verwimp A.  

Authors (Pub.)

Mamontov Yu. S. Heinrichs J. Schäfer-Verwimp A. Ignatov M. S. Perkovsky E. E.  

Publication

Hepatics from Rovno amber (Ukraine), 2 [2013/12]

Journal

Arctoa

Volume

22

Page number

95

Year

2013

Fossil Status

thallus

Stratigraphy

Priabonian

Strat. comment

35–37 Ma; in amber

Location

Klesov (Pugach quarry), Vladimirets District, Rovno Region, Ukraine

Paleoregion

Eurasia (Europe)

Data for Holotypus

Repository

Schmalhausen Institute of Zoology (SIZK)., National Academy of Sciences of Ukraine, Kyiv, Ukraine

Repository Number

SIZK-K-10052F

Num

1-10

Pub.

Hepatics from Rovno amber (Ukraine), 2 [2013/12]

Diagnosis

Sterile, unbranched, creeping shoot, ca. 6 mm long and up to 2 mm wide. Stem robust, visible only between some underleaves which are bent downwards, with incubous foliation. Leaves alternating, imbricate, with U-shaped insertion, dorsally deeply interlocking and covering the whole stem. Lobes concave in ventral view, 0.70-1.35 mm long and 0.5-0.9 mm wide, asymetrically ovate-oblong, margins entire, reflexed to ventral side; dorsal margin curved outwards, apex rounded, broadly incurved towards the ventral side of the stem; ventral margin sinuate, free ventral margin taking ca. 0.50-0.66 of lobe with widely curved transition to keel. Cells of lobes regularly arranged in curving rows, hexagonal; cell walls thin, not sinuate, trigones large, cordate, not sinuate; intermediate thickenings present. Median lobe cells 15-18 μm wide, 20-27 μm long, marginal cells subisodiametric, 18-23 μm in diam., similar to median leaf cells in shape and size but overall slightly less elongate. Cuticle smooth throughout. Larger leaf cells indicating ocelli not observed. Keel at an angle of 15-45°, 0.3(-0.5) the leaf lobe length, moderately arched, at base convex; the rear narrowly rounded distally, towards base becoming broadly rounded. Lobule large, widest near apex, 0.35-0.44 mm long and 0.25-0.37 mm wide; the portion adjacent to keel inflated; free margin flat, appressed to lobe, not clearly visible throughout but at least with two indistinct teeth. Underleaves with somewhat inverted U-shaped insertion, weakly imbricate to slightly distant, suborbicular to reniform, entire-margined, 377-485 μm wide, 250-320 μm long, ca. 1.5-1.6× wider than long, about 3.2-5.4 times wider than stem, not decurrent, with rounded to almost cordate base, touching the stem or strongly reflexed to ventral side. Lamina concave or convex, without distinct area of rhizoid initials. Upper part of shoot (ca. 1/3 of the whole length) abruptly bent upwards, suberect, with smaller leaves, some of them detached and possibly serving for vegetative distribution.