Corresponding author: Christopher T. Martine (
Academic editor: Sandra Knapp
A bush tomato that has evaded classification by solanologists for decades has been identified and is described as a new species belonging to the Australian “
McDonnell AJ, Wetreich HB, Cantley JT, Jobson P, Martine CT (2019)
As one of the most species-rich angiosperm genera (
The spiny solanums appear to have arrived in Australia some time in the last 5–10 million years (
The new taxon is the latest in a series of novelties from a set of taxa and forms within the “andromonoecious bush tomato” clade (
In this paper, we describe
Morphology and the earliest-known herbarium specimen of
Fieldwork in Northern Territory during 2016 facilitated collection of specimens with male flowers and tissue for population genomic study (in prep), which has revealed that this new entity is an independently evolving lineage (unpublished data). The same population was visited again in 2018 and facilitated the collection of specimens with complete andromonoecious inflorescences (including both male and hermaphrodite flowers) and mature fruits with viable seeds, as well as information about population size, extent and local ecology. Specimens were examined from BUPL,
Field-collected seeds from two subpopulations were cultivated ex situ. First, seeds were soaked for 24 hours in 1000 ppm gibberellic acid solution in the dark at room temperature. Seeds were then sown in a growth chamber that was programmed to mimic an
Closely related species of andromonoecious bush tomatoes included in this study.
Comparison of characters was conducted using JMP Pro 12 (SAS Institute, Inc., Cary, North Carolina, USA). Analyses included one-way ANOVA with Student’s t-test mean comparison at P < 0.05 and all the pairs by Tukey HSD to compare means and discern which species are different and in what way. A Connecting Letters Report was also generated to summarise mean values of each character across the six taxa included and to determine and assign significantly different sets when applicable. Multivariate morphometric analysis for all six taxa was also conducted using a principal components analysis (
ANOVA comparisons of each character along with Student’s t-tests and the Tukey HSD post-hoc comparisons reveal that species of this complex are, in large part, morphologically distinct (Table
The
Principal components analysis score plot with eigenvalues and the contribution of each PC displayed (left) and loading plot (right) of characters and species in Table
Vegetative and reproductive characters measured for species included in this study along with associated means (M), standard deviations (
|
|
|
|
|
||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Stem prickle length | 0.22 | 0.09 | 30 | D | 0.4 | 0.1 | 16 | A | 0.29 | 0.12 | 54 | BC | 0.37 | 0.07 | 20 | AB | 0.26 | 0.1 | 24 | CD | 0.38 | 0.12 | 25 | A |
Internode length | 2.23 | 0.91 | 30 | B | 2.16 | 0.67 | 16 | B | 1.48 | 0.51 | 54 | C | 3.6 | 0.73 | 25 | A | 4.01 | 0.98 | 24 | A | 1.48 | 0.43 | 25 | C |
Petiole length | 1.03 | 0.53 | 30 | D | 2.68 | 0.8 | 16 | B | 0.82 | 0.39 | 54 | D | 1.78 | 0.44 | 25 | C | 3.36 | 0.78 | 24 | A | 0.79 | 0.32 | 25 | D |
Apical leaf length | 2.66 | 0.77 | 25 | C | 11.32 | 1.83 | 16 | A | 5.39 | 1.33 | 25 | B | 5.13 | 1.09 | 25 | B | 12.39 | 2.51 | 24 | A | 4.97 | 0.89 | 25 | B |
Apical leaf width | 1.61 | 0.41 | 25 | B | 1.41 | 0.41 | 16 | BC | 1.69 | 1.13 | 25 | B | 1.84 | 0.53 | 25 | B | 2.47 | 0.65 | 24 | A | 1.06 | 0.22 | 25 | C |
Basal leaf length | 5.80 | 1.98 | 25 | D | 13.66 | 2.66 | 16 | B | 9.42 | 1.84 | 25 | C | 9.23 | 2.27 | 25 | C | 16.8 | 3.86 | 24 | A | 8.58 | 1.37 | 25 | C |
Basal leaf width | 3.24 | 0.91 | 25 | C | 2.03 | 0.88 | 16 | D | 4.97 | 1.54 | 25 | A | 4.56 | 1.17 | 25 | AB | 3.97 | 1.16 | 24 | BC | 1.59 | 0.37 | 25 | D |
Trichome density, adaxial, apical leaves | 81.6 | 48.28 | 5 | B | 419 | 125.27 | 5 | A | 121.0 | 61.42 | 5 | B | 345.0 | 43.36 | 5 | A | 138.33 | 20.26 | 3 | B | 482.2 | 79.82 | 5 | A |
Trichome density, abaxial, apical leaves | 162.4 | 82.84 | 5 | B | 453.2 | 103.03 | 5 | A | 156.40 | 47.65 | 5 | B | 412.6 | 63.31 | 5 | A | 206.0 | 20.78 | 3 | B | 491.6 | 79.01 | 5 | A |
Depth of lobing, apical leaves | 0.79 | 0.24 | 15 | A | 0.61 | 0.36 | 20 | AB | 0.9 | 0.62 | 15 | A | 0.91 | 0.4 | 25 | A | 0.27 | 0.36 | 10 | BC | 0.02 | 0.05 | 14 | C |
Depth of lobing, basal leaves | 1.48 | 0.38 | 15 | AB | 1.31 | 0.67 | 12 | B | 2.01 | 0.92 | 15 | A | 1.22 | 0.49 | 18 | B | 0.87 | 0.59 | 6 | B | 0.02 | 0.06 | 14 |
|
Surface area, apical leaves | 2.54 | 1.17 | 25 | C | 3.49 | 2.54 | 25 | C | 3.02 | 1.93 | 25 | C | 9.82 | 3.08 | 20 | A | 10.67 | 6.54 | 25 | A | 6.52 | 2.59 | 20 |
|
Surface area, basal leaves | 9.99 | 4.12 | 25 | B | 7.71 | 1.84 | 7 | B | 19.86 | 7.68 | 25 | A | 23.91 | 9.74 | 20 | A | 16.83 | 7.51 | 4 | AB | 11.63 | 6.58 | 11 | B |
Corolla diameter, male flowers | 2.24 | 0.45 | 16 | D | 3.5 | 0.31 | 15 | B | 3.02 | 0.44 | 23 | C | 3.11 | 0.34 | 25 | BC | 3.97 | 0.62 | 25 | A | 3.07 | 0.62 | 9 | BC |
Corolla diameter, hermaphrodite flowers | 2.96 | 0.37 | 16 | D | 4.12 | 0.35 | 13 | B | 3.58 | 0.5 | 17 | C | 3.77 | 0.45 | 17 | BC | 4.69 | 0.58 | 22 | A | 3.54 | 0.33 | 4 | BCD |
Calyx lobe length, male flowers | 0.35 | 0.09 | 15 | E | 0.69 | 0.06 | 3 | D | 1.16 | 0.14 | 10 | C | 0.17 | 0.02 | 25 | F | 1.13 | 0.14 | 7 | B | 1.63 | 0.03 | 3 |
|
Calyx lobe length, hermaphrodite flowers | 0.35 | 0.09 | 6 | D | 0.9 | 0.15 | 5 | C | 1.65 | 0.14 | 14 | C | 2.41 | 0.33 | 19 | A | 1.78 | 0.52 | 4 | B | 1.72 | 0.05 | 4 | B |
Pedicel length, in fruit | 2.7 | 0.18 | 13 | C | 3.64 | 0.93 | 14 | AB | 1.65 | 0.34 | 12 | D | 3.59 | 0.7 | 8 | AB | 4.16 | 0.72 | 17 | A | 2.94 | 0.47 | 9 | BC |
Fruit length | 3.11 | 0.29 | 14 | A | 1.8 | 0.29 | 13 | C | 1.65 | 0.13 | 3 | BC | 2.88 | 0.26 | 21 | A | 2.15 | 0.34 | 29 | B | 2.0 | 0.37 | 17 | BC |
Fruit width | 2.92 | 0.35 | 14 | A | 2.2 | 0.41 | 13 | B | 1.68 | 0.28 | 3 | B | 2.69 | 0.28 | 21 | A | 1.96 | 0.36 | 29 | B | 2.2 | 0.35 | 17 | B |
Seeds per fruit | 433 | – | 1 | A | 78.69 | 36.67 | 13 | C | 101.67 | 58.6 | 3 | C | 262.81 | 48.26 | 20 | B | 53.11 | 28.45 | 28 | C | 70.08 | 49.87 | 13 | C |
Seed length | 4.11 | 0.25 | 15 | A | 2.84 | 0.21 | 20 | C | 3.09 | 0.21 | 15 | C | 3.6 | 0.35 | 11 | B | 3.05 | 0.18 | 20 | C | 3.45 | 0.38 | 14 | B |
Fruit wall width | 4.4 | – | 1 | AB | 3.1 | – | 1 | AB | 2.20 | – | 1 | B | 4.22 | 0.51 | 6 | AB | 5.5 | – | 1 | A | 3.35 | 0.49 | 2 | AB |
Plant height | 33.8 | 5.35 | 3 | B | 43.62 | 10.86 | 16 | B | 34.08 | 7.3 | 6 | B | 69.2 | 27.03 | 5 | A | 45.85 | 6.91 | 24 | B | 77.33 | 2.52 | 3 | A |
Like
AUSTRALIA. Northern Territory: ~42 km E of Top Springs, on and around the Buchanan Highway,
Erect perennial herb 50–80 cm tall. Stems slender, woody at base, upright even when weighted by fruits; single stemmed, with some lateral branching on mature stems. Foliage and stems grey to grey-green, becoming slightly more yellow-green with age; indumentum of stems, leaves and inflorescences composed of stellate trichomes with the stalk, these short, appressed and very dense throughout (of Type 1
Nothing is known about the biotic interactions local fauna have with this species, although the floral morphology suggests the typical
Map showing geographic distribution of all taxa compared in this study. red points =
The handful of collections that have been made of
The name is based on the Latin “plastus” (“deceptive,” but derived from the Greek “plastikos/plasticos/plasticus” for “able to be molded, changeable”) and the Latin “sexus” for sex. We suggest the use of Dungowan Bush Tomato for the common name of this species, which refers to the cattle station on which the majority of the collections have been made.
Scan of holotype of
Typical habitat of
Couplets 3 and 4 adapted from
1 | Mature plants typically with stems 1 metre or more in height; plants possessing taproots, foliage deep green to yellow-green; occurring in the Top End region |
|
– | Mature plants typically with stems 1 metre or less in height (or rarely ≥ 1 m); plants rhizomatous; foliage grey to blue green to deep green; primarily occurring south of Mataranka |
|
2 | Foliage yellow-green to rusty-green; leaves with several shallow or deep rounded lobes; plants perennial; typically along riverbanks around southern Gulf of Carpentaria |
|
– | Foliage bright or deep green; leaves ovate to oval with none or few pointed lobes; plants biennial; mostly restricted to northern/western escarpments of the Arnhem Plateau (and Wessel Islands) |
|
3 | Leaves sessile; stellate hairs on upper leaf surface with lateral rays more or less porrect (held horizontally) | |
– | Leaves petiolate; stellate hairs on upper leaf surface mostly with ascending lateral rays |
|
4 | Fruiting calyx with 2300–2700 prickles; male flowers with pedicels 3–11 mm long |
|
– | Fruiting calyx with 190–310 prickles; male flowers with pedicels 11–16 mm long |
|
5 | Erect herbs or shrubs (though branches may become lax and the plants sprawl slightly in fruiting stage) |
|
– | Compact to weakly erect or sprawling herbs or shrubs |
|
6 | Plants greater than 0.5 metre in height at maturity |
|
– | Plants 0.5 metre or less in height at maturity |
|
7 | Leaf blades lanceolate; lobes, if any, with sinuses less than 0.2 cm in depth |
|
– | Leaf blades elliptic, ovate or rarely lanceolate; lobes frequently with sinuses ≥ 0.5 cm in depth |
|
8 | Leaves dissected; leaf blades ovate to oblong, 2–4 cm long, sparsely pubescent |
|
– | Leaves deeply lobed; leaf blades ovate to elliptic, 2.5–8 cm long, densely pubescent |
|
9 | Leaves deep green; leaf blades linear, dissected, lanceolate or elliptic |
|
– | Leaves grey-green; leaf blades ovate |
|
10 | Leaf blades linear to dissected with narrow lobes or ovate to elliptic and lobed; berries globose; restricted to eastern Northern Territory, Limmen National Park region |
|
– | Leaf blades lanceolate to elliptic and unlobed to shallowly lobed; berries ovoid; restricted to western Northern Territory, Bullita Homestead, Judbarra National Park and vicinity |
|
11 | Leaf margins shallowly lobed to entire, sinuate; fruit a dry berry |
|
– | Leaf margins shallowly to deeply lobed, crenate to irregularly parted; fruit a juicy berry |
|
12 | Plants compact, typically much less than 0.5 m tall; restricted to north-western Northern Territory, west of Timber Creek, in the East Baines River corridor |
|
– | Plants weakly erect to sprawling, typically reaching 1 m tall; widespread in Northern Territory and western Queensland |
|
For at least five decades, the species described here has evaded easy classification by field botanists. The earliest known collections by Latz (
Given this apparent ability to exhibit elements of all three possible breeding systems, we have chosen the name
This work would not have been possible without generous assistance from staff of the Northern Territory Herbaria at Palmerston (