A new species of Navicella from Costa Rica Abdulkadir E. Elshafie 1 , Andre Aptroot 2 , Saif N.Al-Bahry 3 & Abdulaziz Y. Al-Kindi 4 M>4 Biology Department, College of Science, Sultan Qaboos University, PO Box 36 Al Khod, Muscat, Sultanate of Oman, PC123. 2 Centraalbureau voor Schimmelcultures, PO Box 85167, NL-3508 AD Utrecht, The Netherlands Elshafie A. E., Aptroot A., Al-Bahry S. N. & Al-Kindi A. Y. (2005). A new species of Navicella from Costa Rica. - Sydowia 57 (1): 19-22. Navicella costaricensis sp. nov., isolated from plant debris in the rain forest of Costa Rica, is described and illustrated. The species is characterized by cylindrical ostioles and dark brown, long-ellipsoid, distoseptate ascospores with hyaline end cells that are separated by dark septa from the other cells. The ascospores have lenticular lumina. Key Word: Navicella, Costa Rica, culture, plant debris, rain forest. The genus Navicella accommodates saprobic ascomycetes, which often grow on bark in both temperate and tropical regions. It is most reminiscent of the genera in the family Lophiostomataceae, by its combination of globose, closed ascomata and often a slit-like ostiole, but the ascospores are distoseptate with thickened septa and lenti- cular lumina, and the asci have a wide endotunica and thin ring around the ocular chamber (Eriksson, 1981). This circumscription has been accepted by Holm & Holm (1988) who placed the genus in the family Lophiostomataceae (Pleosporales). Barr (1990) moved the genus to Massariaceae (Melanommatales) on the basis that the asco- mata and hamathecium are melanommataceous rather than pleos- poraceous, and on the basis of the structrure of the asci and the distoseptate ascospores. Recent molecular work (Liew et al., 2000) has shown that neither the family Lophiostomataceae nor the orders Melanommatales and Pleosporales are monophyletic. At present, the genus Navicella comprises five species; N. ele- gans Fabre, N. püeata (Tode: Fries) Fabre (Barr, 1990), N. xinjian- gensis Yuan (Yuan and Zhao, 1994), N. pallida Aptroot (Aptroot & van Iperen, 1998) and N. diabola Aptroot (Aptroot, 2003). The main characteristics of our fungus do perfectly match the genus, but not * e-mail: elshafie@squ.edu.com 19 ©Verlag Ferdinand Berger & Söhne Ges.m.b.H., Horn, Austria, download unter www.biologiezentrum.at