| Hydnora arabica Bolin & Musselman|
in Bolin, Lupton & Musselman, 2018.
The plant parasite Hydnora arabica (Aristolochiaceae) is described from the Arabian Peninsula. This species was previously identified as Hydnora africana in Oman. It can be separated from other Hydnora taxa primarily by its terete rhizome, red to orange inner perianth tube color, and tepal lobe margins entirely covered with dense strigose setae. In Oman, Hydnora arabica is known to parasitize two leguminous trees: Acacia tortilis and the introduced Pithocellobium dulce, but may parasitize additional Fabaceae. At least eleven synonyms or subspecific varieties of H. abyssinica are described in the literature, all from east or southern Africa. These synonyms are discussed in light of new observations of morphology including tepal margin ornamentation. A new key for Hydnora is proposed.
Keywords: parasitic plant, Hydnoraceae, Magnoliids
Hydnora arabica Bolin & Musselman, sp. nov.
Diagnosis: — Hydnora arabica is similar to Hydnora abyssinica, but can be distinguished by having red to orange inner perianth tube color and tepal lobe margins entirely covered with dense strigose setae.
Distribution:—Known from southern Oman (Dhofar region) and Yemen. Collected from an elevation of 200 to 680 m (Fig. 1).
Habitat and Ecology:—Hydnora arabica is an obligate root parasite of Fabaceae that is visible above the soil surface only when flowering (Fig. 2). Most of our collections in Oman occurred on Acacia tortilis and the same host was reported from Yemen (Al-Fatimi 2015). Interestingly, in a small Dhofar settlement approximately 16 km NE of Mirbat, adjacent to Ayn Ayuoon south of Jebel Samhan, we were directed to a robust H. arabica population associated with and below the non-native Pithocellobium dulce (5 m high) in the settlement courtyard and goat yard. No other potential host trees were within 50 meters, thus P. dulce was likely the host plant. The villagers mentioned that the goats fed in the nearby wadi where H. arabica was abundant and were the likely vector of Hydnora seeds into the settlement. Interestingly, in Madagascar, the same introduced host P. dulce was a common host of H. esculenta (Bolin and Musselman 2013).
Etymology:—The specific epithet refers to the distribution of H. arabica on the Arabian Peninsula.
Vernacular Name:— Thesiger reported the vernacular name as dhanuna on herbarium material from the 1940s. Miller and Morris (1998) give the Jibbali name xamleg and the Dhofari Arabic names khamlayyeh and khumla’ah. We can confirm that Jibbali settlers in Dhofar that knew the plant well as a potential food item in fruit used the name xamleg. From Yemen in the districts of Lawdar and Dathina that use the plant the Arabic local names of nabeekh, fateekh, and tarateef (Al-Fatimi et al. 2015) are used.
Conservation Status:— In the Dhofar region of Oman, dried rhizomes of H. arabica were common in most wadi beds with an abundance of its common host Acacia tortilis, though fresh flowering material was difficult to locate due to its infrequent flowering and primarily hypogeous habit. Based on our observations, the conservation status of H. arabica in southern Oman is secure. However, H. abyssinica is reported as rare in Saudi Arabia (Collenette 1999) and we have little basis to comment on H. arabica abundance in Yemen.
Jay F. Bolin, Darach Lupton and Lytton J. Musselman. 2018. Hydnora arabica (Aristolochiaceae), A New Species from the Arabian Peninsula and A Key to Hydnora. Phytotaxa. 388(1); 99–108. DOI: 10.11646/phytotaxa.338.1.8