Wednesday, January 2, 2019

[Botany • 2018] Bruguiera × dungarra (Rhizophoraceae) • A New Hybrid between Mangrove Species B. exaristata and B. gymnorhiza recently discovered in north-east Australia

Bruguiera × dungarra  N.C.Duke & Hidetoshi Kudo
in Duke & Kudo, 2018. 

Bruguiera × dungarra (Rhizophoraceae), a previously undescribed hybrid species between B. exaristata and B. gymnorhiza is recorded from north-east Australia. Eight taxa are currently recognised in this Indo West Pacific genus, including three putative hybrids. The newly described hybrid is widely occurring, and it is described here with notes provided on typification, phenology, distribution and habitat. A revised identification key to all Bruguiera taxa is presented, along with a table of comparative diagnostic characters.

Keywords: Bruguiera × dungarra; Rhizophoraceae; hybrid; identification key; intermediate; mangrove; taxonomy

Fig. 4 Bruguiera × dungarra N.C.Duke & Kudo, hybrid nov. a. Foliage with inflorescences; b. trunk and exposed roots; c. habit; d. bark; e. leaves upper and lower surfaces; f. open and closed flower buds; g. leafy rosette with flower buds and mature propagule; h. mature hypocotyl; l. leaf scar node; j. colleter at inner base of interpetiolar stipule; k. petal dehisced and open; l. calyces of mature propagule, expended flower and closed flower bud; m. diagram of open petal (bar length = 10 mm); n. sectioned flower bud showing petals and style. — Collection field reference images for Hidetoshi Kudo & Brian Venables, HK190916A, (CNS!), Cairns, Machans Beach.

Bruguiera × dungarra N.C.Duke & Hidetoshi Kudo, hybrid nov.

Etymology. The location of the type of this new hybrid occurs on the ancestral lands of the Yirrganydji people. For these traditional custodians of the narrow coastal strip from Cairns to Port Douglas, the epithet Dungarra means, ‘belonging to Machans Beach area’.

Distribution — Type location is Machans Beach, near Cairns in Queensland,Australia. Other localities include Holloways Beach also near Cairns in Queensland, Australia, south to around Hinchinbrook Channel and Shoalwater Bay, and further north to the Marrett River estuary in Princess Charlotte Bay. Distribution elsewhere is likely, although possibly restricted to the zone of overlap of putative parents (Fig. 3). Putative parent species co-occur in eastern Indonesia, Timor Leste, southern New Guinea and northern Australia. In Australia, B. × dungarra is likely to occur from Darwin Harbour in the Northern Territory to Port Curtis in Queensland. 

Ecology & Local influences — Uncommon hybrid in the midhigh intertidal zone of intermediate estuarine position (sensu Duke 2006). Often in proximity of stands of higher intertidal B. exaristata, and mid-high intertidal B. gymnorhiza.

Norm C. Duke and Hidetoshi Kudo. 2018. Bruguiera × dungarra, A New Hybrid between Mangrove Species B. exaristata and B. gymnorhiza (Rhizophoraceae) recently discovered in north-east Australia. Blumea - Biodiversity, Evolution and Biogeography of Plants.  DOI:  10.3767/blumea.2018.63.03.03

A Cairns-based citizen scientist has made yet another remarkable discovery.