Troglomyces tetralabiatus Santam., Enghoff & Reboleira, 2018

Santamaría, Sergi, Enghoff, Henrik & Reboleira, Ana Sofía P. S., 2018, New species of Troglomyces and Diplopodomyces (Laboulbeniales, Ascomycota) from millipedes (Diplopoda), European Journal of Taxonomy 429, pp. 1-20 : 13-16

Troglomyces tetralabiatus Santam., Enghoff & Reboleira sp. nov.

MycoBank No: MB824140

Fig. 5

Diagnosis

Similar but different from Troglomyces bilabiatus Santam. & Enghoff (Enghoff & Santamaría 2015) in having four protuberant perithecial apical lips instead of two.

Etymology

The species epithet is in relation to the four elongated lips on the perithecial apex.

Material examined

Holotype

GEORGIA: Abhkazia, Western Caucasus, Krubera-Voronya Cave (“deepest cave on Earth”) , collected from 60 to 1980 meters below the surface, on Heterocaucaseuma deprofundum Antić & Reboleira, 2018 (Chordeumatida) , 27 Jul.-9 Aug. 2010, S. Reboleira & A. Sendra leg., slide C-F-92270 .

Isotypes

GEORGIA: Same data as holotype. Slides SS E613a , SS E613b , SS E613c , SS E613d and SS E613f ( BCB-Mycotheca).

Paratypes RUSSIA: Peshchera Yuzhnyi Slon-“Southern Elephant”, Mt. Dzentu, Karachaevo-Cherkessia Republic, 1784 m a.s.l., on legs of the holotype of Caucaseuma elephantum Antić & Makarov, 2016 , no collecting date, Efremova leg., slides SS E615a and SS E615b (BCB-Mycotheca); Krasnodar Province, near Apsheronsk, Cave Sukhaya, on legs of the holotype of Caucaseuma minellii Antić & Makarov, 2016 , 21 Jul. 1970, S. Ljovuschkin leg., slide SS E616 (BCB-Mycotheca); Krasnodar Prov., Sochi, Abkhunskaya, Mt. Bolshoy, Akhun Cave, on Caucaseuma lohmanderi Strasser, 1970 , 12 Jul. 2015, Turbasov leg., slides SS E614a and SS E614b (BCB-Mycotheca); Cave Shirokopokosskaya, near Khosta, on Caucaseuma lohmanderi, Dec. 1943 , Y.A. Birstein leg., slide SS E618 (BCB-Mycotheca); Caucasus, Spirokoposkaja Cave, on Caucaseuma lohmanderi, Jul. 1943 , J. Birstein leg., slide SS E584a and SS E584c (BCB- Mycotheca).

Description

Thallus hyaline, except for the blackened foot.

Basal cell (I) 1.5‒3 times as long as broad, enlarged distally, strongly constricted at the base. Suprabasal cell (II) twice as broad as long, laterally adnate to cell VI, broadened at base where in contact with cell I, narrowed toward distal end. Cell III very narrow, up to 7 times as long as broad; laterally adnate to the perithecium, extending up to a third of the total length of the perithecium (lips included). Septum I-II horizontal. Septum II-III very short and oblique.

Primary appendage branched above the second and successive cells, rarely above first cell ( Fig. 5D ); short, not extending beyond the perithecial apex. Basal cell of primary appendage longer than other cells of appendage, about 2 times as long as broad. Primary septum constricted, strongly oblique. Antheridia flask-shaped, only clearly seen on immature thalli; usually a single one borne directly on second cell of appendage, sometimes supported by a short branch; sometimes a second and even a third antheridium may be found on the branches above. Antheridia deteriorate after maturation of thallus. Spiny remains of spore apex (sx) not seen.

Perithecial stalk cell (VI) inconspicuous, strongly flattened. Perithecium conical, the broadest part at the base, gradually tapering upwards. The apex bears 4 conspicuous identical, often distinctly divergent and curved lips, about 7 times as long as broad, arising through a scar.

Length from foot to apex of perithecium (including lips) 86‒112 µm. Perithecium (including basal cells and lips) 60‒73 × 15‒18 µm. Length of perithecial apical lips 10‒18 µm. Primary appendage (from primary septum to apex, undamaged) 21‒33 µm.

Remarks

Among the hosts examined there are some with heavy infection on legs ( Fig. 5A ). Thalli found near the gonopods (slide SS E613f) are slightly different from others, therefore may be considered a growth form. Interesting are the digitations penetrating the tegument observed in some feet ( Fig. 5I ‒K ).

As mentioned in the diagnosis, this species is similar to Troglomyces bilabiatus , which lives on Acipes spp. ( Blaniulidae ) from Madeira and Canary Islands ( Enghoff & Santamaría 2015). Troglomyces tetralabiatus Santam., Enghoff & Reboleira sp. nov. differs from Troglomyces bilabiatus by having four apical lobes instead of two, its more slender habitus and branched appendage. However, despite the morphological similarity it is hard to imagine a close relationship between two fungi living on such geographically and taxonomically isolated hosts.

The scar near the perithecial apex ( Fig. 5C , arrows) was already described and discussed for five other species of Troglomyces ( Enghoff & Santamaría 2015) .

The hosts are cave-dwelling species of Western Caucasian anthroleucosomatid millipedes, belonging to genus Heterocaucaseuma and Caucaseuma . This species was found living in a cave at the remarkable depth of 1980 meters below the surface in the Krubera-Voronja Cave ( Sendra & Reboleira 2012; Antić et al. 2018). This makes it the “deepest” Laboulbeniales species on Earth. No significant difference regarding fungal position or thallus density was found when comparing hosts collected at different depths inside the cave.

Figures

Fig. 5. Troglomyces tetralabiatus Santam., Enghoff & Reboleira sp. nov. A. Leg covered with thalli (see arrows for thalli, dark dots are blackened feet). B. Antheridium with spermatium. C. Mature thallus, with focus on scars near perithecial apex (arrows). D. Mature thallus with labelling of cells and other elements. E. Detail of perithecial apex showing the four conspicuous lips. F. Immature thallus with trichogyne (tr). G–H. Detail of well-developed primary appendages. I–K. Details of feet with digitations in side view (I‒J) and in front view (K). Scale bars 100 µm (A), 50 µm (F), 25 µm (C‒D), and 10 µm (B, E, G‒K). Photographs from: slides SS E614a (A), SS E615b (B), SS E584c (C), SS E613f (D), SS E613b (E), C-F-92270 (F) and SS E584b (G‒K).