Monographs Details: Abuta pahni (Mart.) Krukoff & Barneby
Authority: Barneby, Rupert C. & Krukoff, Boris A. 1971. Supplementary notes on American Menispermaceae. VIII. A generic survey of the American Tricilisisae and Anomospermeae. Mem. New York Bot. Gard. 22: 1-89.
Family:Menispermaceae
Description:Distribution and Ecology - Distribution (23 collections): Brazil (basins of Rios Madeira, Jurua, Japura, the upper SoUmoes and the upper Rio Negro in the State of Amazonas, and basin of Rio Purus in the State of Acre); Peru (Loreto, Huanuco, and Junin); Ecuador (Napo-Pastaza); Venezuela (Merida). Doubtless to be found in Colombia. VENEZUELA. Merida: Steyermark 56700 ([female]) (along Rio Ona, near Bolero, alt 545-915 m), Bernardi 2360 ([male]) ("Panamericana, Cerro Lancudo"). BRAZIL. Amazonas: basin of the upper Rio Negro, Schultes & Pires 9029 (Rio Vaupes), basin of Rio Japura: Martius 3057B (M—holotype), basin of Rio Madeira, Krukoff 5978 ([male]), basin of Rio Jurua, Froes 21708, basin of the upper Rio Solimoes, Froes 12088, 12091; Acre: basin of the upper Rio Purus, Krukoff 5437 (iris). PERU. Loreto: Mathias & Taylor 3894 (near Iquitos), 5017 (near Aguaytia); Huanuco: Mathias & Taylor 4054, 4056, 4058, 4087, and 4097 (aU near Tingo Maria), 5040 ("don Diogenes"), Schunke 1969/6 (Pachitea); Junin: Schunke 1961/11 (Quimirisur, alt ± 809 m), Woytkowski 6006 (Mazamari, alt 1000 m ) (GH, MO, US). ECUADOR. Upper Bobonaza, alt ± 1900 ft. Fuller 4, 98 (frts) (NY-holotype of A. ecuadorensis), 97.

Discussion:

Fig. 2.

Cocculus pahni Martius, Flora 24(Beibl. 2): 45. 1841.

Abuta ecuadorensis Moldenke, Phytologia 6: 322. 1958.

As may be seen above of 23 known collections only two have staminate flowers, one pistillate flowers, and two fruits.

This segregate from A. rufescens may be distinguished from sympatric Amazonian relatives, except A. mycetandra, by the finely reticulate upper leaf-surface, and by the thin and short pilosulous pubescence of the lower, confined mostly to the principal nerves. We cannot compare the staminate flower with that of A. rufescens itself, but as will be seen from accompanying figures it is very different in size, proportions of the sepals, and form of the androecium from that of A. splendida, A. mycetandra, or the allopatric A. convexa. At its western limit in the inter-Andean valleys in Peru and northward, A. pahni enters the range of A. aristeguietae, and here again we are unable to make a full diagnostic comparison, the staminate flower of .A. aristeguietae being still unknown. Young leaves of A. aristeguietae have the secondary nerves more elevated on the upper side than in A. pahni, but this is not a character that can be fully reUed on and we must turn to the large lenticellate fruit of A. aristeguietae to find a firm basis for separation.

Leaves of A. pahni vary considerably in texture according to age and exposure. Young leaves and shade-leaves are submembranous to thinly chartaceous, and plane between the secondary venation, but leaves associated with flowers and fruits, presumably from the forest canopy, are more leathery and incipiently buUate, with areoles shallowly depressed between the smallest veinlets beneath. The material we have seen presents, nevertheless, a chain of transitions connecting the extremes. The leaves of the type of A. pahni are a quite close match for those of typical A. ecuadorensis, both being of the plane, chartaceous type.

Since Eichler in Flora BrasiUensis referred Cocculus pahni to A. rufescens, the species has been lost sight of as a distinct entity. The concept of A. ecuadorensis, here reduced to A. pahni, is a partial exception to this statement, but it was from the beginning insubstantial, based on a single example of soft, newly expanded leaves accompanied by a few detached drupes. No complete pistillate inflorescence and no staminate flowers were ever associated with the type of A. ecuadorensis. Abuta pahni is an ingredient of curare of the Juris (basin of Rio Japura, Amazonas, Brazil) on the authority of Martius (see Brittonia 3: 67).

The collectors note on the label (Mathias & Taylor 4054): "cut surface of liana yellow," and on the other label (Mathias & Taylor 4087): "large liana with yellow root." The stems of this species are round and not flat (Mathias & Taylor 3894). In Loreto (Peru) the species is in flower in July.

Distribution:Brazil South America| Peru South America| Ecuador South America| Venezuela South America| Colombia South America|