The exact evolutionary affinities of the myxomycetes are still debated, but these organisms constitute a well-defined and homogenous group (class: Myxomycetes) of approximately 875 species (Lado, 2001) worldwide. However, only 252 species of this group is documented for Turkey (Sesli et al. 2016). Therefore, it is required to taxonomically study this group to add more species to the existing checklist, which is recorded for the flora of Turkey.
The genus Diderma has c. 132 taxa of 75 species all over the world. In Turkey, these species, including D. chondrioderma (de Bary & Rostaf.) G.Lister, D. crustaceum Peck, D. hemisphaericum (Bull.) Hornem, D. niveum (Rostaf) T. Macbr., D. testaceum (Schrad.) Pers., D. cinereum Morgan, D. carneum Nann.-Bremek., D. umbilicatum Pers., D. deplanatum Fr. and D. radiatum (L.) Morgan have been previously documented (Baba & Tamer, 2008; Oran and Ergül, 2015; Sesli et. al. 2016).
During routine field trips to several locations of, Gökçeada (older name in Turkish: Imroz; Greek: Ίμβρος - Imbros), which is the largest island of Turkey, the part of Çanakkale province numerous samples of myxomycetes were collected in November 2006. Based on the available checklists provided by Ergül & Dülger (2000), Sesli & Denchev (2005), Dulger (2007), Yagız & Afyon (2007), Sesli & Denchev (2009) and Sesli et al. (2016), Diderma effusum (Schw.) Morgan (Didymiaceae) is a new record for Turkey.
MATERIALS AND METHODS
The myxomycetes fructification bodies have been obtained by using of the moist chamber technique in vitro. Searching in the literatures plays a crucial role leading to the identification of the mentioned taxon. (Martin & Alexopoulos 1969, Farr, 1976, Thind 1977, Nannenga-Bremekamp 1991). Microscopic photographs were taken with the Leica DM 2500 Trinoculer Microscope and Leica DFC 280 Model Camera in the pallinology laboratory. Macroscopic photographs were taken with the Nikon E8400 Model Camera. This specimen is deposited at the Herbarium of Çanakkale Onsekiz Mart University (CNH), Çanakkale - Turkey as well as in the personal collection of the first author.
Based on the research performed by Seçmen & Leblebici (1978), the botanical flora of the island is belonged to the Mediterranean Phytogeographical Region. The woody plants of the locality are Quercus coccifera L., Q. infectoria Oliv. subsp. infectoria, Phillyrea latifolia L., Sarcopoterium spinosum (L.) Spach, Cistus creticus L., and Arbutus andrachne L.
RESULT AND DISCUSSION
Diderma effusum (Schwein.) Morgan, J. Cincinnati Soc. Nat. Hist. 16: 155 (1894); Fig. 1.
Synonyms ≡ Physarum effusum Schwein., Trans. Amer.
Philos. Soc. 4:257 (1832). = Diderma reticulatum (Rostaf.) Morgan, J.
Cincinnati Soc. Nat.Hist. 16: 155 (1894). Fructification structures composed of flattened white sporangia massed in plasmodiocarpous fashion, applanate, reticulate, or often forming a broadly effused low pulvinate, 0.2–0.4 mm height, ovoid or longer than wide to oblong, 0.5–1.5 mm wide and 0.6 to well over 1 cm long. Hypothallus is common to a group, membranous and inconspicuous. Peridium of two separated layers, the outer a thin, smooth, white or almost white, calcareous crust closely applied to the delicate membranous and the inner wall membranous as well as colourless or rose-lilac dehiscing irregularly but not together. Columella alutaceous, depressed pulvinate and white to reddish brown, sometimes limited to a thin layer of lime on the base, and covering most of the base. Capillitium thin, colourless or pale lilac–brown, consisting of abundant short threads somewhat branched toward their distal extremities with few interconnections. Spores in mass brown and lilac-brown in transmitted light, verruculose with faint clusters of larger warts, seeming almost smooth, some in denser groups, 8–9 (–10) μm in diameter. Plasmodium is white colour (Fig. 1).
Fig. 1. Diderma effusum. a. The group of plasmodiocarps on bark under the dissection microscope. — Scale bar = 1 mm. b. Two layers of the peridium. — Scale bar = 1 mm. c. Capillitial threads on LM. — Scale bar = 10 μm. d. Micrograph of spores. — Scale bar = 10 μm.
Specimens examined. Turkey, Çanakkale, Gökçeada, Junction of Tepeköy, 40° 10' 48.13" N, 25° 50' 51.95" E, elevation 99 m, on barks of Quercus coccifera, 26 Nov. 2006, Tülay Bican Süerdem 40; Fig. 2.
Diderma effusum can be recognised by the typical depressed, smooth, white sporangia or plasmodiocarpic fructification bodies and by its rather small pale spores. Taxonomically, D. effusum is the closest species to the D. deplanatum and D. testaceum but D. deplanatum is more plasmodiocarpous and has larger and darker spores. Previously, it was recorded from Turkey (Baba, 2012). Occasionally, D. testaceum has pale spores. In this case, two species are similar to each other. But D. testaceum is typically smaller and the sporangia are rarely crowded; also has a dark red or rust-brown columella. Commonly, D. effusum is confused with some Didymium species such as D. difforme, D. comatum and D. tubulatum, but all of them have a compact lime shell of chrystalline structure which is visible (with difficulty) on the broken edges. They have larger and darker spores with exception of D. comatum, (Nannenga-Bremekamp 1991). The spore diameter of D. effusum is diverse ranging from 7–10 μm (Martin & Alexopoulos, 1969; Thind, 1977; Nannenga-Bremekamp, 1991) or 6–10 μm (Farr, 1976), respectively. The spore diameter of the identified specimen is in agreement with that of mentioned in the literatures, which is mostly 8–9 μm.
Fig. 2. The presence of Diderma effusum in Turkey, pointed by “ ”.