Benstonea rupestris (B. C. Stone) Callm. & Buerki

Callmander, Martin W., Lowry Ii, Porter P., Forest, Félix, Devey, Dion S., Beentje, Henk & Buerki, Sven, 2012, Benstonea Callm. & Buerki (Pandanaceae): characterization, circumscription, and distribution of a new genus of screw-pines, with a synopsis of accepted species, Candollea 67 (2), pp. 323-345 : 338

38. Benstonea rupestris (B. C. Stone) Callm. & Buerki , comb. nova.

≡ Pandanus rupestris B. C. Stone in Fed. Mus. J. 14: 129. 1972.

Typus: MALAYSIA. Sarawak (Borneo): Bukit Pantu, Melinau , Kapit, 9.VIII.1967, llias Paie 25728 (holo-: SAR!).

= Pandanus oresbios B. C. Stone in Fed. Mus. J. 23: 58. 1978.

Typus: INDONESIA. Kalimatan (Borneo): Central E, near Mt. Kemul , 12.X.1925, Endert 3896 (holo-: L [ L0050606 ] image seen ; iso-: A [ A00019993 ] image seen) ,

syn. nov.

= Pandanus scandens B. C. Stone in Fed. Mus. J. 23: 59. 1978.

Typus: MALAYSIA. Sarawak (Borneo): Bintulu, Merurong Plateau , 16.IV.1960, Brunig 29924 (holo-: SAR!) ,

syn. nov.

Distribution and ecology. – Benstonea rupestris is endemic to the lowland rainforests of Sabah and Sarawak (Borneo).

Observations. – STONE (1978) described Pandanus scandens based on a more mature infructescence than that of P. rupestris , which was described six years earlier. He distinguished these two taxa based on the number of syncarps (5 in P.scandens vs 7 to 9 in P. rupestris ) and other minor morphological characters such as the leaf length (c. 3 Χ 105 cm vs 3-4 190 cm) and color (glaucous vs not glaucous beneath). Recent observations in the field by MWC and SB have, however, confirmed that populations corresponding to Benstonea rupestris are characterized by along pendent infructescence with up to 9 oblong syncarps (sometimes 5 to 8) and that leaf length and width fall within the normal variation of B.rupestris as currently circumscribed ( Fig. 5C ).

Pandanus oresbios , also described in 1978, is here considered as a synonym of Benstonea rupestris . It was described based on an immature infructescence, and despite its apparent narrower leaves (2 cm vs 3-4 cm in B. rupestris ) and smaller syncarps (c. 3.5 cm in length vs 8 cm), it appears to represent the same entity as B.rupestris . Further field observations are needed to understand the relationship between B.rupestris and B.calcinacta , another species that may also be part of this group but is provisionally accepted here (see above).

Figures

Fig. 5. – Infructescences and details of stigmas of species of Benstonea Callm. & Buerki. A. Benstonea parva (Ridl.) Callm. & Buerki; B. Benstonea pectinata (Martelli) Callm. & Buerki; C. Benstonea rupestris (. C. Stone) Callm. & Buerki; D. Benstonea thomissophylla (. C. Stone) Callm. & Buerki. [Photos: M. W. Callmander]