New intergeneric orchid hybrid found in Romania × Pseudorhiza nieschalkii (Senghas) P.F.Hunt nothosubsp. siculorum H.Kertész & N.Anghelescu, 2020

Abstract

We describe the first reported intergeneric, which naturally occurs between two subspecies belonging to different genera, Dactylorhiza fuchsii subsp. sooana (genus Dactylorhiza) and Pseudorchis albida subsp. tricuspis (genus Pseudorchis), as × Pseudorhiza nieschalkii (Senghas) P.F.Hunt nothosubsp. siculorum H.Kertész & N.Anghelescu, 2020. The hybrid was found and digitally photographed for the first time by Hajnalka Kertész in June, 2020, within Terra Siculorum, in one of the Natura 2000 protected areas, known as Harghita Mădăraș, ROSCI00090. Following detailed morphometric analysis using 67 characters and molecular karyological analyses, we identified this unique specimen as an intergeneric hybrid, new to science. The hybrid, an F1 generation plant, most likely representing a single intergeneric pollination event, is phenotypically intermediate between its parental species in most of the characters scored, but it significantly closely resembles Pseudorchis albida subsp. tricuspis parent. Since several individuals of the parental species occurred in near proximity, within 1–10 meters distance, we suggest that the production of this hybrid required a minimum travel distance of ca 1–10 meters, by the pollinators and frequent exchange of pollen between the parental species was very likely. The parental species and the hybrid, which display a considerable synchronicity in their flowering time, overlap in the pollinator community, sharing various species of Hymenopterans and Dipterans, very abundant in the heathland. This Terra Siculorum hybrid is thus best described as a rarely occurring intergeneric hybrid that shows strong Pseudorchis albida subsp. tricuspis parental dominance in inheritance patterns.

Epipactis bucegensis—A Separate Autogamous Species within the E. helleborine Alliance

“…To enable autogamy, the pollen should be able to reach the stigma. This is achieved by various adaptations of the flower morphology [30]. The transition from chasmogamous to cleistogamous flowers and some modifications in the architecture of the gynostemium and pollinia structure enable the flowers to switch the pollination strategy from allogamy to (near-) obligate autogamy [31,32].…”

“…We found only minute droplets of nectar that accumulated inside the hypochile of the one to two topmost, young flowers (Figure 2E). Minute nectar production was reported several times in other autogams, such as Epipactis albensis Nováková and Rydlo [17,33,35], Epipactis muelleri Godfery [11] and Epipactis leptochila (Godfery) Godfery [30]. These obligate autogams are relatively young species that recently diverged from within the evolutionarily active Epipactis helleborine alliance [36].…”

“…The above examples constitute indicative examples of species that transition from ancestral allogamous, insect-pollinating species to obligate autogamy. While still retaining some early features, such as nectar and scent production, these orchids became obligate autogamous/cleistogamous, making insects' visits nearly impossible [30]. The synthesis of floral attractants or stimuli, i.e., olfactive (scent, odours), food (nectar, food bodies, exudates) and visual stimuli (pigments, colours, shapes, sizes), is highly energy-costly for the plants [37,38].…”

“…Therefore, the actual pollination syndrome or the reproductive strategy can be significantly influenced by floral ontogeny (age of the flowers), environment (temperature, high or low humidity, drying winds, etc.) or both [30,61,62]. Nevertheless, the evolutionary (morphological) transition from obligate allogams to obligate autogams is the result of a combination of developmental genetic, epigenetic and ecophenotypic factors, as a consequence of both prolonged natural selection pressure and genetic drift [36].…”

“…Anthropogenic factors, mainly the destruction and loss of the original habitats (agriculture, urban expansions, deforestation, etc. ), leaving only small suitable patches for the orchids, probably also contributed to the switch of pollination mode and reproductive strategy [30]. Regardless of the presence or absence of pollinators, independence from insects offers orchids an opportunity to conquer new habitats, assuring unconditional, certain reproductive success [71,[74][75][76].…”