Funariaceae. Genus Entosthodon
1. Capsules symmetric or nearly symmetric, straight; peristome teeth rudimentary or moderately developed, but shorter than 250 µm long (excepting E. commutatus) —
— Capsules asymmetric, curved; peristome teeth well developed, longer than 250 µm long —
2. Peristome absent, rudimentary, or weakly developed, shorter than 100 µm long —
— Peristome moderately reduced, longer than 100 µm long —
3. Leaves lanceolate —
— Leaves obovate, elliptic, ovate to ovate-lanceolate —
4. Peristome simple, rudimentary, just exceeding the urn mouth; spores 14–18 µm
— E. angustifolius
A species of the Middle East and Central Asia, it can be expected to occur in xeric areas near the Caspian Sea. Diagnostic features of this species include narrow leaves and almost eperistomate capsules.
— Peristome double, weakly developed, to 75 µm long; spores 24–32 µm —
6. E. stenophyllus
This endemic species of Dagestan is similar to E. angustifolium in having narrow leaves, but differs in having a better developed, double peristome.
5. Upper exothecial cells isodiametric to short rectangular, 1–2:1 —
4. E. fascicularis
Known in Russia only from the Caucasus. It differs from other species of the genus with reduced peristomes in having short exothecial cells.
— Upper exothecial cells elongate, 3–5(–7):1 —
6. Upper exothecial cells thin-walled, in transverse section with semilunate thickenings on the periclinal (outer) cell walls; spores 18–23 µm —
7. E. abramovae
An endemic species of Dagestan characterized by erect capsules; reduced double peristomes up to 75 µm long; small (17–23 mm) spores; and semilunate thickenings on the outer periclinal exothecial cell walls that appear thin-walled from the outside.
— Upper exothecial cells thick-walled, in transverse section with cuneate-triangular thickenings on the anticlinal (lateral) cell walls; spores 23–35 µm —
7. Leaf margins clearly bordered above by one row of narrow, rather thick walled, yellowish to brownish cells —
8. E. handelii
This species is known in Russia only from the Caucasus. It differs from E. fascicularis in having elongate exothecial cells, and from E. abramovae in having larger spores and exothecial cells that appear thick-walled from the outside.
— Leaf margins not bordered —
8. Leaves obovate, widest above mid-leaf; costae usually reaching 1/2 leaf length; opercula plane-convex
— E. duriaei
A Mediterranean species also known from the Middle East; it should be expected in Caucasus. It is distinguished by its obovate leaves and plane-convex operculum.
— Leaves ovate-lanceolate, widest below mid-leaf; costae usually reaching 5/6 or more leaf length; opercula rostrate —
5. E. hungaricus
This xeric and often halophytic species occurs in the steppe zone of European Russia and Siberia. It is a small plant with eperistomate capsules and narrow, thick-walled exothecial cells.
9(2). Leaf margins distinctly bordered above by one row of narrow, thick-walled cells; leaf apices widely acute with short, attenuate apicula
— E. attenuatus
A relatively widespread European, West Asian and North African species, characterized by distinctly bordered leaves.
— Leaf margins not bordered or indistinctly bordered by one row of narrow cells; leaf apices shortly acuminate or with long-filiform acumina —
10. Leaves short-acuminate; leaf margins entire; costae ending well below leaf apices; peristome to 320 µm long
— E. commutatus
A Mediterranean species that may occur in the Caucasus. Characteristic features of the species include shortly acuminate leaves and relatively short costae. Entosthodon duriaei is somewhat similar but differs in having a reduced peristome.
— Leaves long, filiform acuminate; leaf margins serrate distally; costae subpercurrent or percurrent; peristome to 150 µm long —
3. E. dagestanicus
This species is endemic of Dagestan and known only from the holotype. It is characterized by filiform leaf acumina, costae that end in acumina, a double peristome up to 150 µm long, and short (2–3 µm long) setae.
11(1). Leaf margins distinctly bordered, serrate above; costae percurrent or subpercurrent —
2. E. muhlenbergii
In Russia this species is known only from a few xeric localities in the Caucasus. Its distinctly bordered, serrate leaf margins and longer costae distinguish it from E. pulchellus, which was not separated from E. muhlenbergii in older publications.
— Leaf margins indistinctly bordered, entire to slightly crenulate above; costae ending well below leaf apices —
1. E. pulchellus
This species has a scattered distribution in Siberia and the Russian Far East where it grows on soil and rocks, usually in more or less xeric environments.