DOI: 10.5061/dryad.83bk3jb0z
title: Quantitative morphological data on Ramomarthamyces octomerus fungi (Ascomycota)

description: Ramomarthamyces octomerus sp. nov. is described here. This apothecial
 fungus is described from specimens collected in Mediterranean climate
 regions in southern Portugal, Spain (Canary Islands), and the Dalmatian
 region of Croatia. Presumably saprobic, R. octomerus occurs on intact,
 decorticated wood of Laurus novocanariensis and Olea europaea. Ascospores
 are cylindric-ellipsoid and seven-septate. Surprisingly, in our four-locus
 phylogenetic analysis (nuSSU, ITS1-5.8S-ITS2, LSU, mtSSU), this fungus
 clusters among species of Cyclaneusma, Marthamyces, Naemacyclus, and
 Ramomarthamyces in a core Marthamycetaceae clade that circumscribes
 primarily leaf-inhabiting, filiform-spored species. In addition, the asci
 of R. octomerus possess an amyloid pore, but the reaction varies between
 specimens collected in the Canary Islands and those collected in Portugal
 and Croatia. The occurrence of an amyloid reaction in the asci of R.
 octomerus challenges the characterization of Marthamycetales taxa as
 possessing inamyloid asci. In our discussion, we provide background and
 analysis of these notable observations and justify our rationale for
 retaining R. octomerus in Ramomarthamyces rather than creating a new genus
 to accommodate it. We also provide notes on the laurel forest habitat of
 Garajonay National Park on La Gomera island, Canary Islands, Spain, which
 is a UNESCO World Heritage Site and where the holotype of R. octomerus was
 collected.
description: Macromorphological observations of apothecia were made using an
 Olympus SZX9 or a Motic SMZ-168 stereomicroscope. Photomicrographs were
 made using transmitted light microscopy with an Olympus BX51 compound
 light microscope with 40×, 100×/1.30 oil immersion plan-achromatic
 objectives, together with an Olympus XC50 5.0-megapixel digital camera and
 Olympus cellSens Standard 1.14 image processing software.
 To study the structure of apothecia and tissue types following
 [28: pp. 32–34], longitudinal sections through the midpoint of an
 apothecium were made by hand-sectioning with the aid of a stereomicroscope
 or by using a freezing stage mounted to a sliding microtome. Hand sections
 were made to observe living cells and tissues. The freezing microtome
 apparatus facilitated making sections that were uniform and thin (~15–25
 µm). To make these, pieces of substratum supporting an apothecium were
 hydrated, soaked in a solution of dilute gum Arabic, and oriented on an
 electric, water-cooled, freezing stage (Physitemp BFS-5MP) mounted to a
 sliding microtome. Additional dilute gum Arabic was added to completely
 envelop the sample in a supportive matrix so it would not be damaged
 during sectioning. The microtome was set to make ~ 15 µm sections for
 routine observation, but 20–25 µm sections or greater were routinely made
 for species with asci wider than 15 µm. Sections were placed in water on a
 microscope slide and studied with the aid of a stereomicroscope to select
 the widest sections, which are from the middle of the
 apothecium. To study mature, living ascospores that
 were discharged from recently collected apothecia, we followed the
 procedure outlined in Karakehian et al. (2021. Asian Journal of Mycology
 4(2): 1–18). Briefly, recently collected apothecia were hydrated and
 maintained in a moist chamber with a coverglass suspended over them to
 collect discharged ascospores. The cover glasses bearing living ascospores
 were mounted in a drop of tap water on a microscope slide and observed
 using transmitted light microscopy within a few hours of being
 discharged. We used these same microscopy preparations
 to measure dead ascospores. The ascospores were killed by drawing a drop
 of KOH or MLZ under the cover glass. Because of this approach, we could
 not make measurements of individual ascospores in both living and dead
 states. In other words, any given measurement of a dead ascospore was
 likely not made from the same, single ascospore in the living state. We
 separated the living and dead ascospore measurements into two spreadsheets
 to try to avoid a user assuming that a given row represented measurements
 from a single, individual ascospore in both the living and dead
 states.
description: # Quantitative morphological data on *Ramomarthamyces octomerus* fungi
 (Ascomycota)
 [https://doi.org/10.5061/dryad.83bk3jb0z](https://doi.org/10.5061/dryad.83bk3jb0z) ## Description of the data and file structure Quantitative data includes ascospore length/width measurements from living and dead ascospores, as well as apothecium, paraphyses, ascus, and other micromorphological features. The data was obtained from the holotype and paratype specimens of *Ramomarthamyces octomerus* (Ascomycota, Leotiomycetes, Marthamycetales, Marthamycetaceae) (ILLS00122394: HOLOTYPE. ILLS00122395: PARATYPE). Potential uses might include a comparison of ascospore morphology in the living vs dead states. There are four files. The "Data_Ramomarthamyces octomerus_all measurements except ascospores" file contains morphological data of apothecia except ascospore measurements, the "Data_Ramomarthamyces_octomerus_ascospore_measurements_dead" are measurements from dead ascospores only, and "Data_Ramomarthamyces_octomerus_ascospore_measurements_living" contains measurements from living ascospores only. The "Metadata_Ramomarthamyces octomerus" file contains the definitions of the field titles in the data file as well as some notes on methodology. ## Sharing/Access information NA ## Code/Software NA