Sanango

Full name and orig. publication: Sanango Bunting & Duke, Ann. Missouri Bot. Gard. 48: 270 (1961).

Etymology: The name is the colloquial name furnished by the inigeneous collector of theplant. It is a corruption of a Quechuan word, "sanangu", an Indian word also applied to other plants.

Synonyms: Gomara Ruiz & Pav. (1794), non Adans. (1763), Gomaria Spreng. (1831), Gomaranthus S.Rauschert (1982).

Infrafamilial position: Sanangoideae (Weber et al. 2013).

Description: Small tree, c. 15 m tall, with very hard wood. Leaves opposite, petiolate, the margins joined accross the shoot axis, lamina elliptical to obovate, apex acute-acuminate, base attenuate. Inflorescence a terminal, bracteose thyrse; bracts and their axillary pair-flowered cymes opposite. Sepals connate in the lower part, narrow triangular, ± equal. Corolla tubular, tube curved and slightly gibbous in the lower part, limb subregular, lobes rounded, with cochlear aestivation in bud. Stamens 4, included, adnate to the corolla base; filaments inflated; anthers subglobose, introrse, versatile, dehiscent by a single, horseshoe-shaped line. Staminode present, small. Nectary cup-shaped, ± as high as the ovary. Ovary superior (wrongly referred to as semi-inferior in the recent literature), globose, slightly 4-partite; incompletely divided in the upper part, completely divided (with axile placentae) in the lower part; style very short; stigma capitate-bilobed, the lobes laterally joined with the style and directing downwards. Fruit a hard-bony capsule, depressed at the apex, style (for a long time) persisting, dehiscence at first septicidal, then loculicidal.

Chromosome number: 2n = 32 (M. Kiehn, unpubl.).

Type and only species: Sanango durum Bunting & Duke, type = S. racemosum (Ruiz & Pav.) Barringer.

Distribution: Peru and SE Ecuador (W central Amazonas and C Junin).

Ecology: In forests between 300 and 750 m altitude.

Notes:
(1) The familial position of this monotypic genus was uncertain for a long time. It was formerly placed in the families Loganiaceae, Buddlejaceae and Scrophulariaceae. More recently, and based on a joint project investigating the genus in anatomical, chemical and molecular respects (Dickison 1994, Jensen 1994, Norman 1994, Wiehler 1994), Sanango was considered to belong to Gesneriaceae by some authors. The molecular data of Smith et al. (1997) and Smith & Carroll (1997) seemed to confirm this view and referred Sanango to the Gesnerioideae tribe Gesnerieae, a position supported neither by morphological nor by phytogeographical data. For a more detailed description of the taxonomic history see Weber et al. (2013: 70-71).
(2) Later molecular studies (Oxelman et al. 1999, 2005), Bremer et al. (2001, 2002) and especially Perret et al. (2013), see review in Möller & Clark 2013) however, indicated a sister position to Gesneriaceae. From the two options, either to create a monospecific family for Sanango, or to include it in Gesneriaceae as a third subfamily, the second variant was chosen by Weber et al. (2013). At any rate, Sanango shares a common ancestor from which all traditional Gesneriaceae evolved.
(3) Morphologically, Sanango fits fairly well into Gesneriaceae (e.g., presence of pair-flowered cymes), with closer affinity to Gesnerioideae than to Didymocarpoideae. On the other hand, and not unexpectedly, the genus exhibits some characters found in neither of the two subfamilies (e.g. cup-shaped nectary ± as high as the ovary, ovary globose and slightly 4-partite, style arising from a depression on the ovary top, bony capsular fruit).
(4) Biogeographically remarkable is the disjunct distribution of Sanango: lower Amazonian slopes of the Andes (NW Peru and SE Ecuador) and central Peru (central Junin region).

Selected references: Dickison, Taxon 43: 601-618 (1994), fl. anat.; Jensen, Taxon 43: 619-623 (1994), pytochem.; Norman, Taxon 43: 591-600, anat.; Wiehler, Taxon 43: 625-632 (1994), syst., Smith et al., Taxon 46: 65-74 (1997), mol. syst.; Smith & Carrol, Syst. Bot. 22: 713-724 (1997), mol. syst.; Oxelman et al., Syst. Bot. 24(2): 164-182 (1999), mol. syst.; Oxelman et al., Taxon 54(2): 411-425 (2005), mol. syst.; Bremer et al., Plant Syst. Evol. 229: 137-169 (2001), mol. syst.; Bremer et al., Mol. Phylogen. Evol. 24: 247-301 (2002), mol. syst.; Perret et al., Bot. J. Linn. Soc. 171(1). 61-79 (2013), mol. syst.; Möller & Clark, Selbyana 31(2): 95-125 (2013), review mol. syst.; Weber et al., Selbyana 31(2): 68-94 (2013), classif. Gesn.

Tax. details, cytology, and bibliography: Gesneriaceae Resource Centre (GRC). Royal Botanic Garden Edinburgh.

Page content and update responsibility/contact: Anton Weber.
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