It is a hybrid extremely low. In the Soller Valley of Mallorca Island I know only a single individual in a crack in a limestone in the bed of a stream flowing down from the mountains surrounding the valley. Share the crack with one parent, the Ceterach officinarum ssp. officinarum and a Asplenium trichomanes ssp. quadrivalens. In its allotetraploid genome has 50% of chromosomes of Ceterach officinarum ssp. officinarum, 25% of Asplenium fontanum and 25% of Asplenium petrarchae ssp. bivalens. It is therefore a trihybrid with chromosomes of three different ferns Aspleniaceae family, an allotetraploid with 144 chromosomes (2n = 144, n = 72).
In this picture the three ferns are sharing the same crack: the Asplenoceterach barrancense, its parent Ceterach officinarum ssp. officinarum and a copy of Asplenium trichomanes ssp. quadrivalens.
At the same rock, in a more shaded area, there is a large population of its parent Asplenium majoricum. The torrent remains dry for most of the year. (Double click on the photo to enlarge)
Combined photography with the family, both parents and child trihybrid
Frond well developed in December.
Photomicrograph of the underside of a pinna with sori partly covered by indusium and abundant paleae more narrow and filiform than the Ceterach officinarum. (Double click on the photo to enlarge)
Asplenium fontanum--> X <--A. petrarchae ssp. bivalens Asplenium javorkeanum
( Hibridación interespecífica ) ( Apomeiosis )
Asplenium majoricum -------> X <------- Ceterach officinarum ssp. officinarum
( FFPP ) l ( CCCC )
( Hibridación interespecífica )
Asplenoceterach barrancense .........................
( FPCC )
Detail of mature sori indusium lifted revealing the sporangia. (Double click on the photo to enlarge)
Sori of the parents of Asplenoceterach barrancense.
And to finish the proof of sterility, aborted spores, dead and partially decomposed unfeasible. Under the microscope there are very few spores and the few that seem to be practically empty or broken. Cultivating the spores in a lunch box after three years there was no germination.