Saturday, July 6, 2024

[Botany • 2024] Orophea chalermprakiat (Annonaceae: Malmeoideae) • A New Species from Satun UNESCO Global Geopark, southern Thailand

 Orophea chalermprakiat Damth., Chanthamrong & Chaowasku, 

in Damthongdee, Chanthamrong, Promsiri, Tongsang, Jaisamut, Wiya, Sinbumroong et Chaowasku, 2024.  
“เฉลิมพระเกียรติ” DOI: 10.11646/phytotaxa.658.3.8

Orophea Blume (1825: 18) (Annonaceae) consists of about 62 species distributed collectively from the Indian subcontinent through mainland Southeast Asia and southern China to the Southeast Asian islands (not further to the east than the Moluccas; Kessler 1988). It is a member of Miliuseae, the largest tribe of Malmeoideae (Chatrou et al. 2012). The genus is primarily characterised by the presence of (1) dissimilar petal whorls, the inner petals being usually longer, clawed toward the base and usually connivent at anthesis, (2) reduced number of stamens and carpels per flower and (3) loosely arranged stamens with a minute connective prolongation not covering the thecae (Damthongdee et al. 2021). Furthermore, most species of Orophea possess varying shapes of glands inside the inner petals (Kessler 1988, Leonardía & Kessler 2001). The genus has been subdivided into two subgenera: Orophea and Sphaerocarpon Kessler (1988: 13). Members of O. subg. Orophea possess generally percurrent tertiary leaf venation and ellipsoid-cylindrical to cylindrical monocarps (± moniliform when multi-seeded), whereas members of O. subg. Sphaerocarpon exhibit generally reticulate tertiary leaf venation and globose (rarely shortly oblongoid) monocarps (Damthongdee et al. 2021). In Thailand, there are eight species, including the recently described O. sichaikhanii Damthongdee, Aongyong & Chaowasku (2021: 308). In this study, we describe a new species of O. subg. Sphaerocarpon from Satun UNESCO Global Geopark, Satun Province, southern Thailand. The indumentum terminology of Hewson (1988) was used. Floral organs were studied and measured from material in spirit.

  Holotype of Orophea chalermprakiat (Chaowasku 219, CMUB).

 Orophea chalermprakiat.
 A. Inflorescence and flower. B. Close-up of (A) in upright position, showing stamens surrounding carpels. C. Inner petal, adaxial (left) and abaxial (right) sides. D. Outer petal, adaxial (left) and abaxial (right) sides. E. Flower with petals and stamens removed, showing adaxial side of sepals and carpels on torus. F. Same as (E) but in bottom view, showing abaxial side of sepals. G. Infructescence and submature monocarps. H. Seed.
 A–F from Chaowasku 219 (CMUB), G–H from Chaowasku 223 (CMUB). C–F from spirit material. Photographs by A. Damthongdee (A, G).

Orophea chalermprakiat Damth., Chanthamrong & Chaowasku, sp. nov. 

 Type:—THAILAND. Satun Prov.: La-ngu Distr., (holotype: CMUB003998801; isotypes: BK, CMUB, PBM, QBG). 

The new species is morphologically most like O. sichaikhanii but differs from it by having pilose-villous young twigs and petioles, shorter petioles, rounded to subcordate (rarely obtuse) leaf bases, shorter flowering pedicels, longer inner petal claws, lower number of carpels per flower and longer monocarp stipes (Table 1).

Distribution:—Endemic to Satun Province, southern Thailand. 

Habitat and phenology:—Evergreen forests in a limestone sink, ca. 25 m. Flowering and fruiting material collected in November.

Etymology:—Derived from a Thai royal term meaning “honour”, the specific epithet honours King Rama X of Thailand [Phra Wachiraklao Chao Yu Hua] on the auspicious occasion of his 72nd (6th cycle) birthday anniversary (28 July 2024). 

Anissara Damthongdee, Kithisak Chanthamrong, Suwannee Promsiri, Banchong Tongsang, Thani Jaisamut, Chattida Wiya, Aroon Sinbumroong and Tanawat Chaowasku. 2024. Orophea chalermprakiat (Annonaceae; Malmeoideae), A New Species from southern Thailand.  Phytotaxa. 658(3); 296-300. DOI: 10.11646/phytotaxa.658.3.8