Gospodinov, Natcheva, 2020, Biologica Nyssana 11(1) 11 (1) September 2020: 31-33 DOI: 10.5281/zenodo.4060289 Chromosome studies of some thalloid liverworts in Bulgaria Original Article Galin Gospodinov Department of Plant and Fungal Diversity and Resources, Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, Sofia, Bulgaria gospodinov.bryol@gmail.com (corresponding author) Rayna Natcheva Department of Plant and Fungal Diversity and Resources, Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, Sofia, Bulgaria renimoss@bio.bas.bg Received: October 01, 2019 Revised: January 22, 2020 Accepted: January 26, 2020 Abstract: Here, we report for the first time chromosome counts for bryophytes from Bulgaria. The mitotic chromosomes from gametophytes of Aneura pinguis, Pellia epiphylla, Pellia neesiana and Riccia fluitans were studied. All counts correspond to previous reports from other parts of the species’ range. Key words: chromosome counts, liverworts, Bulgaria Apstract: Studija hromozoma nekih taloidnih jetrenjača u Bugarskoj Ovde prvi put izveštavamo o broju hromozoma za briofite iz Bugarske. Is- pitivani su mitotički hromozomi iz gametofita Aneura pinguis, Pellia epi- philla, Pellia neesiana i Riccia fluitans. Svi brojevi odgovaraju prethodnim izveštajima iz drugih delova areala vrste. Ključne reči: brojanje hromozoma, jetrenjače, Bugarska Introduction Chromosome studies are a useful tool for taxono- mists (Fritsch, 1978). Unfortunately, chromosome studies concerning bryophytes in Europe are spo- radic and represent chromosome numbers from a limited number of local populations. Although chro- mosome numbers in bryophytes are fairly uniform and karyotype analyses are not often informative (Newton, 1979), chromosome counts are a useful tool to distinguish morphologically similar haplo- diploid species pairs. The knowledge on bryophyte chromosome counts was summarized by Fritsch (1991). Notably, information from South-Eastern Europe is missing. Few other publications deal with chromosomes of certain genera of hepatics (Berrie, 1960; Boisselier-Dubaylee & Bischler, 1998; Zheng & Zhu, 2009; Ochyra et al., 2016). The aim of this study was to report chromosome numbers of some thalloid liverworts from Bulgaria. Material and methods The liverworts were collected during different excur- sions and kept alive in a greenhouse, for the purpose of the research. After a period of adaptation a modi- fied Gomori’s haematoxylin staining method was used (Melander & Wingstrand, 1953). Fresh actively growing thallus tips were placed in 0.01% solution of colchicine for 90 min. After washing in distilled H2O they were fixed in Clarke’s solution (3:1 ethyl alcohol/glacial acetic acid) for 2 h at room tempera- ture or in a fridge for 24 h. After washing in distilled H2O the thalli were placed in 1M hydrochloric acid for 40min at 60 °C followed by washing in distilled H2O. The samples were incubated in hydrochloric acid /ether in ratio 1:1 for 15 min at 60 °C, washed in distilled H2O the stained in Gomori’s Hematoxylin for 1.45/2 h at 60 °C. Samples were squashed in 45% acetic acid and observed under a light microscope. © 2020 Gospodinov, Natcheva. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and build upon your work non- commercially under the same license as the original. 31 Results and Discussion Our results were in accordance with already pub- lished chromosome numbers for the respective spe- cies. For Bulgaria this is the first chromosome report for bryophyte species. Aneuraceae Aneura pinguis (L.) Dumort., n = 10 (Fig. 1). Only one exception in the A. pinguis chromosome number is known up to now (Inoe, 1975) where the species shows chromosome number of n = 20. Pelliaceae Pellia epiphylla (L.) Corda, n=9 (Fig. 2). In Europe, diploid number n=18 is present in Pel- lia borealis Lorb, an allopolyploid species with two haploid cryptic species within P. epiphylla as paren- tal taxa (Orzechowska et al., 2010). The presence of P. borealis in Bulgaria was expected but could not be proven by the present study. Pellia neesiana Nees, n=9 (Fig. 3) Most previous studies for this species showed hap- loid chromosome count of n=9 in mitotic counts (Fritsh, 1991) with a single old report of diploid number of n=18 (Showalter, 1927). Ricciaceae Riccia fluitans L., n=8 (Fig. 4) The species shows uniformity of chromosome num- bers within its range as far as it is studied (Fritsch 1991). The only polyploid reports most likely be- long to its close relative Riccia rhenana (Heitz, 1927, Lorbeer, 1934). Acknowledgements. This research is part of project КП-06-Н21/15/19.12.2018 „Cryptic species in Bulgar- ian flora – molecular species delimitation in the Aneura pinguis complex” financed by the National Science Fund of Bulgaria. References Berrie, G. 1960: The Chromosome Numbers of Liverworts (Hepadcae and Anthocerotae). Transactions of the British Bryological Society, 3(5): 688-705. Fritsch R. 1991: Index to bryophyte chromosome counts. Bryophyta Bibliothek, 40: 1–352. Fritsch R. 1978: Chromosome numbers of some Hungarian liverworts. Abstracta Botanica, Vol V, Suppl. 3. Heitz E. 1927: Über multiple und aberrante Chromosomenzahlen. Abhandlungen des Natur- wissenschaftlicher Verein Hamburg, 21(3-4): 47-57. Lorbeer G. 1934: Zytologie der Lebermoose mit besonderer Be-rücksichtigung allgemeiner Chromosomenfragen. I. Teil. Jahrbücher für Wissenschaftliche Botanik, 80: 567-818. 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