Drosera x eloisiana (Droseraceae) and the lectotypification and synonymisation of D. belezeana

Abstract

Pearman & Rumsey (2004) and Stace et al. (2015) give excellent and detailed accounts of the hybrid between Drosera rotundifolia L. andD. intermediaHayne, referring to it asD. x belezeana E.G. Camus. Both state that the several records reported by Webb (reported in Stace, 1975) are erroneous or unsubstantiated and the only confirmed site (in Great Britain and Ireland) is at Godlingston Heath, Dorset. They go on to cite evidence that in Germany and Austria, voucher specimens of the hybrid have also often proved to be misidentified (e.g. T. Huntke in Stace et al., 2015). Through the availability of digital images on the internet, it has come to light recently that the type of D. x belezeana, from France, was also misidentified and is in fact merely D. rotundifolia (Schlauer cited in Bailey (2015)), which I have confirmed. For this reason a new name was coined for the hybrid, Drosera x eloisiana T. S. Bailey, based on a specimen that Bailey collected at Godlingston Heath (Bailey, 2015). The new name is already registered on Index Kewensis and the International Plant Names Index (IPNI, continually updated). Looking at the protologue ofD. x belezeana (Camus, 1891) and at specimens purported to be this hybrid from the type locality which are housed at P (Laboratoire Phanerogamique, Muséum Nationale D’Histoire Naturelle, Paris), now available on the internet, it is clear that they are either D. rotundifolia or D. intermedia or, sometimes, both species on one sheet, but none is the actual hybrid. In fact there is no evidence that this hybrid has ever been recorded in France! A likely explanation, it seems tome, is that Camus (1891), in his paper recording the Drosera in the area around Paris, which included D. x obovata Mert. & W.D.J. Koch (Drosera anglica Hudson ×D. rotundifolia), had decided that D. rotundifolia ×D. intermediawas also a logical likelihood since both parents occur there together. Could it be that he had, in looking for specimens to fulfil his hunch, merely been victim to his own wishful thinking? Presumably Camus had to guess at what the hybrid might look like, since he had never seen it, and he evidently guessed wrong! The hybrid has suborbicular to obovate blades which are always longer than broad (in D. rotundifolia and in the protologue of D. belezeana, the blades are broader than long); in the hybrid the leaves are elevated above the horizontal by 45°–80° (in D. rotundifolia and D. belezeana they are horizontal); in the hybrid there are 8–12 leaves per rosette (in D. rotundifolia and D. belezeana only 4–6). Here I formally lectotypify and synonymise his sadly superfluous name: Drosera rotundifolia L. (1753:1: 253) Drosera belezeana E.G. Camus (1891:198) syn. nov. Lectotype (selected here): France, ‘Seine-et-Oise, Saint-Lèger’ 23 May 1890, Belèze.s.n., Paris Barcode P04963231 (P. image viewed August 2015) http:// sonneratphoto.mnhn.fr/2012/06/06/1/P04963231.jpg. In the protologue, two specimens are indicated, both with the ‘Seine-et-Oise, Saint-Lèger’ locality. These are given as ‘(! 1879); (Mlle Bèleze 1890)’. The Bèleze specimen indicated above has been selected here as lectotype because it is evidently the single plant which, labelled as ‘x Drosera Beleziana G. Cam.’ was drawn by and figured in the protologue of Camus (1891). The protologue description also closely follows this specimen for example in the leaves having a suborbicular blade abruptly contracted at the petiole, the scapes far exceeding the leaves in length. Schlauer (in litt. 2014) notes that a feature diagnostic of D. intermedia that Camus figures in his illustration of D. belezeana and claims is indicative of this purported parent, namely the bend at the base of the largest scape, is “pure fiction” and that it is not even clear that it belongs to the rosette at all since it is broken at the base. Was Camus trying to prop up a weak case? The identity of the other specimen cited by Camus needs a little decoding. The notation ‘!’ today is usually placed after a cited specimen to indicate that an author *Corresponding author: m.cheek@kew.org