Torenia mannii Skan

Fischer, Eberhard & Lachenaud, Olivier, 2013, A new species of Torenia (Linderniaceae) from Gabon, remarks on Torenia mannii Skan, and a key to the African and Madagascan Torenia species, Phytotaxa 125 (1), pp. 40-46 : 42-44

Torenia mannii Skan ( Hemsley & Skan 1906: 336)

Type:— GABON (or RIO MUNI?): Sierra del Crystal , Mann 1663, 1862 (holotype K!; isotype P!) .

Material studied:— RIO MUNI: Parc National de Monte Alen , dalle rocheuse de Monte Alen 1, N 1°40’ E 10°17, frange forestière, 1130 m, 4.07.1999, Parmentier & Nguema 68 (BRLU); Parc National de Monte Alen, dalle rocheuse d’Engong, 5 km à l’ouest du village d‘Engong, N 1°37‘ E 10°18‘, frange forestière inférieure, 1100 m, 11.05.2002, Parmentier & Esono 2852 (BRLU); ibid. Parmentier & Esono 2970 (BRLU) .

Conservation status:—Vulnerable VU B2b(iii). known from only a few collections from Rio Muni and possibly Gabon.

These three collections from Monte Alen National Park , Rio Muni, are the first records since Gustav Mann collected the type in 1862 in the “Sierra del Crystal”. The type locality is generally supposed to be in Gabon, but could equally be in Rio Muni ( Equatorial Guinea), since the Crystal Mountains spread over both countries, and Mann’s itinerary is not precisely known. As there are no further records of T. mannii in Gabon, its occurence in the country needs confirmation, although it is quite likely. The species should be looked for on inselbergs, especially in the Monts de Cristal National Park, parts of which are difficult to access .

A collection from southern Gabon (Wieringa et al. 5033, WAG) cited with doubt under T. mannii in the checklist of Gabonese vascular plants ( Sosef et al. 2006), is definitely not this species (it has much smaller flowers and differently shaped leaves). However, it remains unidentified for now, having some characters of both T. thouarsii and T. dinklagei .

The flower colour of T. mannii is recorded by Parmentier & Esono 2970 as mauve, with two white stripes on the lower lip. The label of the type specimen just states “corolla purple”.

The species grows in fringing forest on inselbergs, at altitudes of 1100–1130 m, a habitat where T. dinklagei also occurs.