Dyplolabia dalywaiana Rivas Plata, Bawingan & Lücking, 2016

Polyiam, Jutarat Kalb Wetchasart, Plata, Eimy Rivas, Bawingan, Paulina A., Kalb, Klaus & Lücking, Robert, 2016, ‘ Missing links’ alive? Novel taxa represent morphological transitions between distinctive phenotypes among extant Graphidaceae (lichenized Ascomycota: Ostropales), Phytotaxa 268 (2), pp. 110-122 : 117-119

Dyplolabia dalywaiana Rivas Plata, Bawingan & Lücking , sp. nov. ( Fig. 6A )

MycoBank MB817437

Differing from other Dyplolabia species in the angular, erumpent asomata with broadly exposed disc and irregular pseudocolumella. Type: ― PHILIPPINES. Nueva Vizcaya (Luzon): Mt. Palali, near Solano ; 16° 26’ N, 121° 13’ E, 1000 m; montane rain forest; on lower trunk in semi-exposed situation; March 2007, Rivas Plata & Lücking 1194D (holotype F).

Thallus corticolous, epiperidermal, yellow-olive, smooth to uneven, with dense, prosoplectenchymatous cortex; photobiont layer with scattered clusters of calcium oxalate crystals.Apothecia erumpent, angular, 1–1.5 mm diam.; disc immersed, thickly white-pruinose, partly covered by margin; proper margin distinct, thick, erect, fissured, black but with a very thick, white cover; thalline margin absent. Excipulum laterally carbonized, jet-black, without discernable structure. Periphysoids absent but hymenium laterally with a broad zone of widely spaced, anastomosing paraphyses embedded in a gelatinous matrix. Pseudocolumella sometimes present, plug-shaped. Hymenium 170–200 μm high; paraphyses unbranched except for lateral areas as described above. Ascospores 8/ascus, uniseriate, muriform with (3–)5 transverse and 1–3 longitudinal septa per segment, 25–30 × 15–20 μm, broadly oval to subglobose, with thick septa and diamond-shaped lumina ( Astrothelium - type), colorless, I– (non-amyloid).

Secondary chemistry: —White cover of ascoma margin C+ red (lecanoric acid).

Etymology: ―This new species is dedicated to the legacy of Charles R. Darwin and his contemporaneous colleagues, Charles Lyell and Afred Russell Wallace, bringing forward the theory of evolution by natural selection and popularizing the use of the term ‘missing link’.

Distribution and ecology: ― Philippines; thus far only known a single collection from the type locality, Mt. Palali, growing on bark of trees in the montane rain forest understory.

Remarks: ― Dyplolabia dalywaiana is a very peculiar species. It was first believed to represent a member of Ocellularia s.lat., similar to the genera Rhabdodiscus and Stegobolus because of the presence of an irregular columella. The close phylogenetic relationship with D. afzelii initially came as a surprise, but closer examination of the material then revealed that this species shares important characters with the latter, namely the ascoma margin forming a carbonized base with a thick white, C+ red cover containing lecanoric acid, and the I-negative, astrothelioid ascospores. Morphologically, D. dalywaiana is transitional between Dyplolabia and Cruentotrema and hence provides an important taxon to explain the close relationship between both genera: its ascomata have a partially exposed disc and lobulate margins, as in Cruentotrema , whereas the internal anatomy and the thick white cover with lecanoric acid place the species in Dyplolabia .

Figures

FIGURE 6. A. Dyplolabia dalywaiana (holotype; thallus with ascomata). B–D. D. oryzoides (B, Brazil, Kalb 31120; C, D, Sri Lanka, Weerakoon 116; thallus with ascomata and ascospores). E–F. D. chumphonensis (holotype; thallus with ascomata and ascospores). Scale = 1 mm, in D, F = 10 μm.