Saturday, November 18, 2017

[Botany • 2017] A Revision of Middletonia (Gesneriaceae) in Thailand


Middletonia gebosa C.Puglisi: A. Habit, showing young fruit; B. Flowers; Mreticulata (Barnett) C.Puglisi: D. Habit; E. Flowers.
Photographs by Preecha Karaket (A, C–E) and David Middleton (B). 

Puglisi & Middleton. 2017. DOI: 10.20531/tfb.2017.45.1.07

ABSTRACT 

The genus Middletonia in Thailand is revised. We recognise four species, including the newly described Middletonia glebosa C.Puglisi and the resurrected M. reticulata (Barnett) C.Puglisi. A key to the species, full descriptions and proposed conservation assessments are provided. 

KEYWORDS: taxonomy, new species, Flora of Thailand

Figure 1. Middletonia gebosa C.Puglisi: A. Habit, showing young fruit; B. Flowers; M. reticulata (Barnett) C.Puglisi: D. Habit; E. Flowers.
Photographs by Preecha Karaket (A, C–E) and David Middleton (B).


MIDDLETONIA C.Puglisi, 
Taxon. 65: 286. 2016. 
Type species: Middletonia multiflora (R.Br.) C.Puglisi.

Five species, found in India, Bangladesh, Bhutan, Myanmar, China, Thailand, Laos, Cambodia, Vietnam and Malaysia. Four in Thailand.


1. Middletonia evrardii (Pellegr.) C.Puglisi, Taxon. 65: 286. 2016

Distribution.— Lao PDR, Vietnam.
Thailand.— EASTERN: Nakhon Ratchasima, CENTRAL: Nakhon Nayok
 Ecology.— Evergreen forest.

Note.— The material from Thailand differs slightly from the Vietnamese material, especially in the leaf shape which is more elongated and with an acute apex in the Thai specimens. As there are rather few specimens from throughout the distribution range, with no floral material from Thailand available for dissection, further collections are necessary to assess whether the Thai and Vietnamese plants belong to one or more species.

2. Middletonia glebosa C.Puglisi, sp. nov. 

Similar to Middletonia regularis in having the inflorescences shorter than the leaves and to Middletonia reticulata in the shortly caulescent habit. Differs from both in having a dense indumentum on the adaxial side of the leaf, with glands and eglandular hispid hairs (upperleafsurface glabrescent or minutely glandular in Middletonia regularis, glabrescent in M. reticulata), and in the short, non-twisted, lumpy and irregular fruit (longer, weakly to strongly twisted, smooth and regular in M. regularis and M. reticulata). 

Type: Thailand, Sukhothai, Ram Kham Haeng National Park, Khao Luang, alt. 520 m, 11 Oct. 2012, fr., Middleton, Karaket, Suddee & Triboun 5559 (holotype E [E00547434]; isotypes BK, BKF [SN201922]).  

Distribution.— Cambodia.
Thailand.— NORTHERN: Sukhothai. 
 Ecology.— Mixed deciduous forest with bamboo on granite bedrock.

Etymology.— The specific epithet is the Latin adjective glebosus, -a, -um, which means “lumpy” and refers to the peculiar surface of the capsule.

Notes.— In Ram Kham Haeng National Park this species grows in a mixed population with Middletonia reticulata. The two are readily told apart in the field by Middletonia glebosa having softer, paler leaves, a shorter inflorescence, generally slightly smaller flowers, and the curious short, straight, lumpy fruit. The species is known only from Ram Kham Haeng National Park and a single collection made around 150 years ago in Cambodia. The Cambodian collection, placed in Paraboea regularis by Xu et al. (2008), is only in fruit so the identification will need to be verified with flowering material. However, the fruit of this species is rather distinctive.


3. Middletonia regularis (Ridl.) C.Puglisi, Taxon. 65: 287. 2016.

Distribution.— Malaysia. 
Thailand.— PENINSULA: Surat Thani, Phangnga; SOUTH-WESTERN: Kanchanaburi.

Ecology.— Lowland evergreen forest on limestone soils. 

Note.— The protologue of Paraboea monticola suggests the flowers to be much larger: “lobes … 6–9 × c. 6.5 mm”. However, none of the material available for this study had lobes longer than 3.3 mm. 

4. Middletonia reticulata (Barnett) C.Puglisi, comb. nov.
Boea reticulata Barnett, Nat. Hist. Bull. Siam Soc. 20: 20. 1961.
Type: Thailand, Chiang Mai, Mae Wang

Ecology.— Mixed deciduous forest on granite bedrock. 

Distribution.— Currently endemic to Thailand but possibly also occurring in Lao PDR and Myanmar.
Thailand.— NORTHERN: Mae Hong Son; Chiang Mai; Lamphun; Lampang; Phrae; Sukhothai. 

 Note.— This species is resurrected from synonymy of Middletonia multiflora (R.Br.) C.Puglisi from which it differs in the distinctively reticulate venation pattern covered in loose brown indumentum on the lower surface of the leaves, and in the auriculate leaf base. Middletonia multiflora has a denser indumentum on the leaf and the tertiary venation is less densely reticulate and less visible altogether. Middletonia multiflora is widespread along the northern distribution of the genus (from India to Vietnam), but none of the material from Thailand studied can be attributed to M. multiflora.


Carmen Puglisi and David J. Middleton. 2017. A Revision of Middletonia (Gesneriaceae) in Thailand. THAI FOREST BULL., BOT. 45(1); 35–41. DOI: 10.20531/tfb.2017.45.1.07

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