Racomitrium chlorocarpum

Bednarek-Ochyra, Halina, 2014, Nomenclatural entanglements associated with Racomitrium chlorocarpum (Grimmiaceae), Phytotaxa 188 (3), pp. 153-161 : 155

Typification of Racomitrium chlorocarpum

According to Art. 7.7 of the current Code ( McNeill et al., 2012) Racomitrium chlorocarpum “is to be typified by an element selected from the entire context” of Hooker’s (1867) description of R. crispulum var. β. This author cited in the protologue the specimens from three distant regions, including the North Island of New Zealand, Tasmania and Îles Kerguelen. During the course of revisionary studies of austral taxa of Bucklandiella some specimens annotated by W. Mitten as Grimmia (Rhacomitrium) chlorocarpa have been located on the sheet stamped “Herbarium Hookerianum” in BM and on the sheet labelled “ Rhacomitrium chlorocarpum (Mitt.) Paris ” in the Mitten Herbarium in NY. Many of them are eligible for selection of a lectotype of R. chlorocarpum .

Of the specimens cited in the protologue no material collected by Colenso from the North Island was found. In the Wilson herbarium in BM there is only a small scrap collected by Colenso in New Zealand (No. 2074), named with a question mark Dryptodon rupestris Hooker & Wilson (1844: 544) and cited by Wilson (1854) and Hooker (1867) under this name. Therefore this specimen cannot be considered as potential material for lectotypification.

The only material from Îles Kerguelen which was cited by Hooker (1867) in the protologue of Racomitrium crispulum var. β is the specimen collected by J. D. Hooker in this archipelago from May to July 1840 and cited in his Flora antarctica as Racomitrium protensum A.Braun ex Duby (1830: 573) var. 3 ( Wilson & Hooker, 1847). No other moss collections were made from this isolated archipelago until 1874 when H. N. Moseley, a naturalist to the Challenger Expedition, collected the specimen named by Mitten (1876a) as Grimmia chlorocarpa . In addition, in January 1875, A. E. Eaton recorded in this archipelago during the British Transit-of-Venus Expedition the specimen named by Mitten (1876b) as Grimmia chlorocarpa . Nevertheless, the latter two specimens are also not eligible for lectotypification of R. chlorocarpum .

The specimen collected by Hooker on Îles Kerguelen was described by Müller (1889) as Grimmia suborthotrichacea Müller (1883: 81) var. robustissima Müller (1889: 30) and this variety is identical to Bucklandiella pachydictyon ( Cardot 1908: 113) Bedn. -Ochyra et Ochyra in Ochyra et al. (2003: 147) ( Ochyra et al., 2008b). Acceptance of this material as lectotype of R. chlorocarpum could seriously disturb the current nomenclature because this name could have priority over R. pachydictyon Cardot (1908: 113) , the basionym of Bucklandiella pachydictyon , described in 1908 ( Cardot, 1908). The latter name is firmly rooted in moss taxonony ( Ochyra et al., 2008a,b; Blockeel et al., 2008; Müller, 2009; Larraín, 2012) and such a change would destabilise the nomenclature.

A good number of specimens which were annotated by W. Mitten as Grimmia chlorocarpa originate from Tasmania and these are available in the Hooker herbarium in BM and in the Mitten herbarium in NY. In fact, these are almost all specimens cited in Flora Tasmaniae under the name Racomitrium crispulum ( Wilson, 1858) . One of the specimens in fine fruiting condition collected by Gunn at St. Patrick’s River is here selected as lectotype of Racomitrium chlorocarpum ( Fig. 1 ). At the same time this species is transferred to Bucklandiella Roiv. as it exhibits all diagnostic features of this genus including smooth laminal cells, short lanceolate peristome teeth irregularly divided in the distal part into 2 − 3 branchlets, and a smooth and dextrorse seta.

Figures

FIGURE 1. The lectotype specimen of Racomitrium chlorocarpum Paris selected from the Hooker herbarium (BM).