Introduction

Ferdinand von Mueller (1825–1896) was the botanist on the North Australian Exploring Expedition that in 1855 and 1856 explored North Australia under the command of A. C. Gregory (Gregory 1858; maps of the expedition are available at http://nla.gov.au/nla.map-rm2807). In mid-September 1855, the expedition’s two ships reached the mouth of the Victoria River, and the explorers then spent eight months exploring the surrounding country. They started their return journey on 21 June 1856. Mueller is not known to have visited the Northern Territory again later (see Orchard 1999, and literature cited there), and although many of his specimens are undated they can be associated with confidence with the North Australian Exploring Expedition on the basis of the locality data.

Many new taxa were collected on that expedition, including two new species of melon described as Cucumis jucundus F. Muell. and Cucumis picrocarpus F. Muell. (Mueller 1859). Both names were subsumed into Cucumis trigonus Roxb. by Bentham (1866), who however noted that they might be forms of Cucumis melo L. In 1993 (pp. 104 and 114), Kirkbride included both as synonyms under Cucumis melo without assigning them to a definite infraspecific taxon. Some of the specimens in CANB and MEL thus referred to Cucumis melo had earlier (in 1986) been annotated by Charles Jeffrey as Cucumis melo subsp. nov., and Kirkbride (1993) also commented on the Australian material’s polymorphism in the degree of leaf dissection and the indumentum of the hypanthium of female flowers.

A phylogenetic reconstruction of Cucumis that includes over 100 accessions from Asia and Australia now indicates that some of the Australian material previously referred to Cucumis melo constitutes distinct species (Sebastian et al. 2010). The molecular data show that Australia harbors seven native species of Cucumis, five of them new to science and described elsewhere (Telford et al. 2011). Examination of Mueller’s collections and protologues indicates that Mueller’s name Cucumis picrocarpus applies to the Australian sister species of the worldwide crop Cucumis melo (and its wild progenitor forms native in India), while Mueller’s Cucumis jucundus is a synonym of Cucumis melo. The possible importance to plant breeders of this Australian sister to Cucumis melo makes it expedient to designate the types of Mueller’s Australian Cucumis names, a task carried out here.

Ongoing molecular-phylogenetic work on Luffa vindicates another of Mueller’s suspected new species, this one never formally described by him. Like the two melon species, he discovered it in the Victoria River region, and there are at least two specimens labeled by Mueller as ‘Luffa saccata.’ Mueller’s manuscript name was listed as a synonym under Luffa graveolens Roxb. by Naudin (1859), a famed Cucurbitaceae specialist, with the result that Mueller’s name went unnoticed for the next 150 years. Luffa graveolens occurs in India, Nepal, Bangladesh, and Burma, and is morphologically distinct from the Australian species. We here validate the name Luffa saccata, describe the morphological differences between Luffa graveolens and Luffa saccata, and provide illustrations.

Taxonomic results and discussion Emended lectotypification of Cucumis jucundus:

Cucumis jucundus F. Muell., Trans. Philos. Inst. Victoria 3: 45 (1859) as ‘jucunda’.

Lectotype (designated here): AUSTRALIA. Northern Territory: Victoria River, undated, F. Mueller (K000634446!, p.p., excluding upper stem with fruit attached; isolectotypes: Same locality, undated, GH000312219! [as ‘Cucurbita jucunda’], K000634445!, MEL000592946! [as ‘Cucurbita jucunda’]). A second sheet at GH from “Depot Creek” and one at MEL000592947 from “Victoria River, Depot Creek” are possible further isolectotypes.

Kirkbride (1993) designated a sheet in the Kew Herbarium (now K000634446; our Fig. 1) as ‘neotype’ of Cucumis jucundus and another one (now K000634445) as ‘neoisotype’ [sic]. In fact, the material on K000634446 represents two species, Cucumis jucundus and Cucumis picrocarpus, both discovered by Mueller during the North Australian Exploring Expedition and described by him (Mueller 1859) on the basis of his own collections. Kirkbride’s ‘neotype’ thus comprises original material for both Cucumis jucundus and Cucumis picrocarpus. Under the Vienna Code (McNeill et al. 2006: Art. 9.8), the term neotype is, in such cases, correctable to lectotype. However, the sheet referred to by Kirkbride is not a specimen as defined in the Code (Art. 8.2), because it does not consist of ‘a single species’. A “second stage lectotypification” as provided for in Art. 9.12 is therefore necessary, to ensure that the name Cucumis jucundus F. Muell. remains attached to those plant parts on K000634446 that “correspond most nearly with the original description or diagnosis.” At least five other sheets annotated by Mueller as Cucumis jucundus or Cucurbita jucunda and coming from different collecting localities (without collecting dates) are kept at MEL, the herbarium of Mueller’s home institution, and the protologue statement about the geographic range of Cucumis jucundus is accordingly broad: ‘In Arnhem’s Land and on the Gulf of Carpentaria, particularly on the banks of rivers, also in eastern tropical Australia, and in Central Australia observed with certainty as far south as Cooper’s River’ (Mueller 1859: 45). The sheet MEL000592946, with male flowers, was collected at ‘Victoria River’ and is undoubtedly a duplicate of our lectotype, same as one of the two specimens kept at GH. A second sheet at GH from “Depot Creek” and one at MEL from “Victoria River, Depot Creek” are possible further isolectotypes.

Lectotypification of Cucumis picrocarpus:

Cucumis picrocarpus F. Muell., Trans. Philos. Inst. Victoria 3: 46 (1859), as ‘picrocarpa’.

Lectotype (designated here): AUSTRALIA. Northern Territory: Victoria River, undated, F. Mueller (K000634697!, p.p., upper stem on sheet, with fruit attached, excluding lower stems).

The upper stem on the sheet K000634697 (our Fig. 1), with an attached fruit, is the only extant specimen of Cucumis picrocarpus known to have been collected prior to publication of the name. Neither a specimen annotated as Cucumis ‘picrocarpa’ by Mueller nor any other original material has been located in MEL. There is thus no option than designating K000634697 as lectotype. The specimen exhibits the deeply lobed leaves and fruit indumentum described in Mueller’s protologue, which does not cite a specimen, only a distributional statement: ‘In many parts of tropical Australia’ (Mueller 1859: 46). According to label information on K000634697, Mueller’s plant was collected in the Victoria River region, where Cucumis picrocarpus grows sympatrically with feral forms of Cucumis melo, also collected there by Mueller and annotated by him as Cucurbita jucunda or Cucumis jucundus (compare our first lectotypification, above). An emended description of Cucumis picrocarpus, a distribution map, and an illustration are provided in Telford et al. (2011).

Description of Luffa saccata: