(2313) Proposal to conserve the name Momordica lanata ( Citrullus lanatus ) (watermelon, Cucurbitaceae ), with a conserved type, against Citrullus battich</I

Abstract

identical to print version). TAXON 63 (4) • August 2014: 941–942 Renner & al. • (2313) Conserve Momordica lanata (2313) Proposal to conserve the name Momordica lanata (Citrullus lanatus) (watermelon, Cucurbitaceae), with a conserved type, against Citrullus battich. rej. prop. Typus non designatus. This proposal originated as a spinoff of new results of DNA sequencing in the genus Citrullus, which put the currently accepted name for the sweet watermelon in jeopardy. While it was being drafted, a second threat to that name surfaced, which is also being taken into account. The watermelon was first validly named by Linnaeus (Sp. Pl.: 1010. 1753) as Cucurbita citrullus L. That name has not as yet been typified effectively (see details in Jarvis, Order Out of Chaos: 465. 2007). According to Jarvis the original material comprises two ele-ments, an illustration (Bauhin & al., Hist. Pl. 2: fig. on p. 236. 1651) and a specimen in the Burser Herbarium. However, the illustration is not an original element. Linnaeus's protologue reference is to Citrul-lus folio colocynthidis secto, semine nigro, on page 235 of Bauhin & al.'s work, where that plant is indeed described but not figured. The figure on the following page (236) is of Gitruli [sic] genus aliud (a different kind), which is described in the text as Citruli genus majus (a larger kind), differing in a number of features of the fruit and seed. Therefore a single original element remains: the specimen of "Anguria Citrullus dicta" in herb. Burser VII: 101 (UPS), that we here formally designate as the (obligate) lectotype. Savage (C. Lin-naei Det. Hort. Sicc. J. Burseri: 57. 1937) confirms that the specimen was examined and identified by Linnaeus before 1753. It is indeed a flowering shoot of the watermelon, as we could verify on the digital images kindly put at our disposal by Mats Hjertson. The nomenclatural history of the watermelon is chequered. For about a century (mid-19th to mid-20th) the name Citrullus vulgaris was in general use for it. However, already in 1930 Bailey (in Gentes Herbarum 2: 180–186) pointed out that "the methods of nomenclature must be liberally interpreted in this case, unless one is willing to adopt the doublet Citrullus Citrullus, and even this double name may not be without doubt". Such doubts were appropriate both at the genus and species level. Ahead of the 1950 Stockholm Congress, Hara proposed conser-vation of Citrullus Forssk. 1775 against two earlier synonyms, Anguria Mill. 1754 and Colocynthis Ludw. 1757, all said to refer to the water-melon. A corresponding preliminary entry appears in the Stockholm Code (Lanjouw & al. in Regnum Veg. 3: 137. 1952). Fosberg (in Taxon 2: 99–101. 1953), having been assigned the proposal for examination, supported it in principle but concluded that Citrullus Forssk., having been proposed without generic description for a genus comprising three species, was not a validly published name. Fosberg therefore suggested that Citrullus be conserved from its publication by Schrader in 1836, with C. vulgaris Schrad. (≡ Cucurbita citrullus L.) as its listed type; and that Citrullus Neck. 1790 be added to the entry as a rejected earlier homonym. This was approved and is what appears in the Paris Code (Lanjouw & al. in Regnum Veg. 8: 273. 1956). Since then, the only changes affecting the entry have been elimination of the Necker homonym (as Necker's generic names had been ruled not to be validly published) and replacement of Colocynthis Ludw. with the earlier, supposedly isonymous Colocynthis Mill. 1754 (Rickett & Stafleu in Taxon 9: 121. 1960). Hara (in Taxon 2: 134–135. 1953) had, in vain, objected to Fosberg's change to his proposal. Of Hara's two arguments, one is spurious (Cucurbita anguria Duchesne 1786 is an illegitimate name and cannot threaten Cucumis vulgaris), but the other is valid. "Though Forskål described three species under Citrullus, the first was the only for which he introduced a binomial … Forskål's Citrullus with only one validly published binomial … may be regarded as a monotypic genus." The Code at that time did not clearly define what a "monotypic genus" is, so both Fosberg's and Hara's interpretations were possible. When the definition eventually was given, first in Art. 42 Note 1 of the Sydney Code (Greuter & al. in Regnum Veg. 111: 39. 1983) and then in Art. 42.2 of the Tokyo Code (Greuter & al. in Regnum Veg. 131: 52. 1994), it confirmed Hara's position. Citrullus Forssk. 1775 is a validly published name, heterotypic although synonymous with Citrullus Schrad., and therefore by implication (ICN Art. 14.10) rejected in favour of the latter as an earlier homonym. [Thanks to a last-minute fix, this is now made explicit in the Citrullus entry in App. III to the Melbourne Code, McNeill & al. in Regnum Veg. 157, in press.]

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941Version of Record (identical to print version).
TAX ON
63 (4) • August 2014: 941–942
Renner & al.
• (2313) Conserve Momordica lanata
(2313) Proposal to conserve the name Momordica lanata (Citrullus lanatus)
(watermelon, Cucurbitaceae), with a conserved type, against Citrullus battich
Susanne S. Renner,1 Guillaume Chomicki1 & Werner Greuter2
1 Systematic Botany and Mycology, Department of Biology, University of Munich (LMU), 80638 München, Germany
2 Herbarium Mediterraneum, Orto Botanico, Via Lincoln 2/A, 90133 Palermo, Italy
Author for correspondence: Werner Greuter, w.greuter@bgbm.org
DOI
http://dx.doi.org/10.12705/634.29
(2313) Momordica lanata Thunb., Prodr. Pl. Cap.: 13. 1794 [Angiosp.:
Cucurbit.], nom. cons. prop.
Typus: Cultivated in St. Louis, Missouri, from seeds of com-
mercial origin, 4 July 2014, S.S. Renner 2816 (M; isotypi: B,
BM, K, L, LE, MO, P, PAL-Gr), typ. cons. prop.
(=) Citrullus battich Forssk., Fl. Aegypt.-Arab.: 167. Jun 1775, nom.
rej. prop.
Typus non designatus.
This proposal originated as a spinoff of new results of DNA
sequencing in the genus Citrullus, which put the currently accepted
name for the sweet watermelon in jeopardy. While it was being
drafted, a second threat to that name surfaced, which is also being
taken into account.
The watermelon was first validly named by Linnaeus (Sp. Pl.:
1010. 1753) as Cucurbita citrullus L. That name has not as yet been
typified effectively (see details in Jarvis, Order Out of Chaos: 465.
2007). According to Jarvis the original material comprises two ele-
ments, an illustration (Bauhin & al., Hist. Pl. 2: fig. on p. 236. 1651)
and a specimen in the Burser Herbarium. However, the illustration is
not an original eleme nt. Lin naeus’s pr otolog ue refere nce i s t o Citrul-
lus folio colocynthidis secto, semine nigro, on page 235 of Bauhin &
al.’s work, where that plant is indeed described but not figured. The
figure on the following page (236) is of Gitruli [sic] genus aliud (a
different kind), which is described in the text as Citruli genus majus
(a larger kind), differing in a number of features of the fruit and
seed. Therefore a single original element remains: the specimen of
“Anguria Citrullus dicta” in herb. Burser VII: 101 (UPS), that we
here formally designate as the (obligate) lectotype. Savage (C. Lin-
naei Det. Hort. Sicc. J. Burseri: 57. 1937) confirms that the specimen
was examined and identified by Linnaeus before 1753. It is indeed a
flowering shoot of the watermelon, as we could verify on the digital
images kindly put at our disposal by Mats Hjertson.
The nomenclatural history of the water melon is chequered. For
about a centu ry (mid-19th to mid-20th) the name Citrullus vulgaris
was in general use for it. However, already in 1930 Bailey (in Gentes
Herbarum 2: 180–186) pointed out that “the methods of nomenclature
must be liberally interpreted in this case, unless one is willing to adopt
the doublet Citrullus Citrullus, and even this double name may not
be without doubt”. Such doubts were appropriate both at the genus
and species level.
Ahead of the 1950 Stockholm Congress, Hara proposed conser-
vation of Citrullus Forssk. 1775 against two earlier synonyms, Anguria
Mill. 1754 and Colocynthis Ludw. 1757, all said to refer to the water-
melon. A corresponding preliminary entry appears in the Stockholm
Code (L anjouw & al. in Reg num Veg. 3: 137. 1952) . Fosbe rg (i n Taxon
2: 99–101. 1953), having been assigned the proposal for examination,
supported it in principle but concluded that Citrullus Forssk., having
been proposed without generic description for a genus comprising
three species, was not a validly published name. Fosberg therefore
suggested that Citrullus be conser ved from its publication by Schrader
in 1836, with C. vulgaris Schrad. (≡ Cucurbita citrullus L.) as its
listed type; and that Citrullus Neck. 1790 be added to the entry as a
rejected earlier homonym. This was approved and is what appears in
the Paris Code (Lanjouw & al. in Regnum Veg. 8: 273. 1956). Since
then, the only changes affecting the entry have been elimination of
the Necker homonym (as Necker’s generic names had been r uled not
to be validly published) and replacement of Colocynthis Ludw. with
the earlier, supposedly isonymous Colocynthis Mill. 1754 (Rickett &
Staf leu in Taxon 9: 121. 1960).
Hara (in Taxon 2: 134–135. 1953) had, in vain, objected to
Fosberg’s change to his proposal. Of Hara’s two arguments, one is
spurious (Cucurbita anguria Duchesne 1786 is an illegitimate name
and cannot threaten Cucumis vulgaris), but the other is valid. “Though
Forskål described three species under Citrullus, the first was the only
for which he introduced a binomial … Forskål’s Citrullus with only
one validly published binomial … may be regarded as a monotypic
genus.” The Code at that time did not clearly define what a “monotypic
genus” is, so both Fosberg’s and Hara’s interpretations were possible.
When the definition eventually was given, first in A rt. 42 Note 1 of
the Sydney Code (Gr euter & al . in Regnu m Veg. 111: 39. 198 3) an d then
in Art. 42.2 of t he Tok yo C ode (Greuter & al. in Regnum Veg. 131: 52.
1994), it confirmed Hara’s position. Citrullus Forssk. 1775 is a validly
published name, heterotypic although synonymous with Citrullus
Schrad., and therefore by implication (ICN Art. 14.10) rejected in
favour of the latter as an earlier homonym. [Thanks to a last-minute
fix, this is now made explicit in the Citrullus entry in App. III to the
Melbourne Code, McNeill & al. in Regnum Veg. 157, in press.]

942 Version of Record (identical to print version).
TAX ON
63 (4) • August 2014: 941–942
Renner & al.
• (2313) Conserve Momordica lanata
At the species level, the correct name of the watermelon is to some
extent conditioned by taxonomic opinion. Bailey (l.c. 1930), Mansfeld
(in Kulturpf lanze, Beih. 2: 421–422. 1959) and many others in their
wake considered the watermelon to include wild southern African
plan ts i n ad ditio n to th e wide ly cu lti vated sweet wa ter melon . Wh ere as
Bailey, disregarding the laws of priority, included Momordica lanata
Thunb., as a variety, in the junior Citrullus vulgaris, Mansfeld drew
the (then inescapable) consequence and accepted Citrullus lanatus as
the correct name of the similarly circumscribed species. It turned out
that what Mansfeld in 1959 believed to be a new combination had in
fact been proposed much earlier, for the same reasons, in a Japanese
seed list: Citrullus lanatus (Thunb.) Matsum. & Nakai, Cat. Sem.
Spor. Hort. Bot. Univ. Imp. Tokyo 1915–1916: 30. 1916 (see Hara in
Taxon 18: 346–347. 1969).
Authors like Bailey, Mansfeld and some others were well aware
of the fact that the plant described by Thunberg was not the sweet
watermelon but a plant growing wild in S. Africa. Citrullus vulgaris
var. lanatus (Thunb.) L.H. Bailey (in Gentes Herbarum 2: 87. 1929)
was proposed to designate “the bitter or wild native watermelon of
South Africa”. Mansfeld (l.c. 1959), similarly, restricted the use of
C. lanatus var. lanatus to the southern African “wild watermelon”.
In Mansfeld, Verz. Landwirtsch. Gärtn. Kulturpf l., ed. 2: 932–934.
1986), C. lanatus is s ubdiv ide d into thre e subs pec ies w ith seve ral vari -
eties, with the sweet watermelon placed in subsp. vulgaris (Schrad.)
Fursa, as var. vulgaris (Schrad.) Fursa, and Thunberg’s S. African
plant in the autonymic subsp. lanatus, as var. lanatus.
However, the inevitable occurred. The sweet water melon came
to be generally known as Citrullus lanatus, irrespective of the fact
that its nomenclatural type represented a different plant. The USDA
Germplasm Resources Information Network, GR IN (http://www.ars
-g rin.gov/cgi -bin/n pgs/ht ml/t axon.pl?314923) a s wel l as Wier sem a &
León’s standard reference book, World Eco n omi c Plan ts (ed. 2: 179.
2013) use C. lanatus var. lanatus for the cultigen, sweet watermelon,
as opposed to var. citroides (L.H. Bailey) Mansf. applied to tsamma
melon, fodder melon and citr us melon. That state of affairs might
have been tolerable as long as all plants traditionally assigned to the
watermelon remained in one and the same species. But new results
of a combined morphological, geographic and molecular analysis
no longer permit to uphold such a concept. Nesom (in Phytoneuron
2011-13: 1–33. 2011) made a first step in that direction, recognising two
species: C. caffer Schrad. (which by implication includes Thunberg’s
type of C. lanatus) and “C. lanatus”, which excludes that type. Our
own results (Chomicki & Renner, submitted) go further along that
path. We analysed nuclear and plastid DNA sequences from all known
Citrullus species, most of them with multiple accessions, including
leaf fragments from the holotype of Momordica lanata (UPS-THUNB
22762) and from the lectotype of Citrullus caffer (GOET 007221;
Nesom, l.c.: 26, fig. 1). We found complete agreement between those
two type specimens (they share, in particular, a unique 30-base-pair
deletion in the plastid gene trnS-trnG). Furthermore, it has become
evident that the sweet watermelon, “C. lanatus”, is not immediately
related to S. Af rican plants but is sister to C. mucosospermus (Fursa)
Fursa from W. Tropical Africa; whereas the southern African popula-
tions form a separate lineage, in which Thunberg’s plant, the annual,
tendril-bearing citron melon (for which the name C. amarus Schrad.
1836 is available, which has priority over C. caffer Schrad. 1838) is
sister to a mor phologically quite distinct species, C. ecirrhosus Cogn.
1888, a perennial that lacks tendrils.
In our opinion, changing the name of as popular and economi-
cally impor tant a plant as the sweet watermelon must not be per-
mitted. It is by far the better solution to condone and legalise the
increasingly erroneous application of the name Citrullus lanatus
by conserving it with a type that, while discordant with Thunberg’s
original intent, sanctions the current all but universal practice. Since
2000 the name C. lanatus has been used in ca. 650 scientific papers
(Web of Science, accessed 25 May 2014) and countless publications
in the applied domain, all relating to the watermelon. The other con-
ceivable alternative, reverting to the once popular C. vulgaris, is not
a realistic option since that name is not available for use anyway
owing to Forsskål’s earlier name. The specimen here proposed as
conserved type of C. lanatus is one of those of which the DNA has
been extracted and sequenced.
Rejection of the present proposal would have two unwelcome
consequences: (1) The correct name of the watermelon would change
from Citrullus lanatus, not to the once familiar C. vulgaris, but to the
utterly unused C. battich Forssk. Forsskål’s name has been discussed
at l en gth by Bailey (l.c. 193 0: 182) w ho, even though no t ype mate rial
has been preserved, was satisfied of the identity of the plant described
with the watermelon, based on the distinctive pattern of seed testa
colour and the coincidence of the ver nacular name with its moder n
use. (2) Application of the name C. lanatus would have to swit ch fro m
sweet watermelon, its present well known meaning, to C. amarus, the
S. African wild citron melon, also cultivated as preser ving melon.
Even t hough C. lanatus has been widely and persistently used for a
taxon not including its type, ICN Art. 57 can no longer be applied if
this proposal should fail.