Syngonanthus, Ruhland, 1900

Giulietti, Ana Maria, Hensold, Nancy, Parra, Lara Regina, Andrade, Maria José Gomes De, Berg, Cassio Van Den & Harley, Raymond Mervyn, 2012, The synonymization of Philodice with Syngonanthus (Eriocaulaceae), Phytotaxa 60 (1), pp. 50-56 : 52

Affinities within Syngonanthus

Syngonanthus cuyabensis is very similar to Syngonanthus xinguensis Moldenke (1964: 489) , a species of Mato Grosso known only from the type and published without sectional designation. Syngonanthus xinguensis is a slightly larger plant, with the stem branched near the apex, which also may occur in S. cuyabensis . Unlike that species, it possesses normal tubular scape spathes 2 cm long which are tightly appressed to the scape. The involucral bracts are white-hyaline with the outer bracts green-striped down the center, as described for Philodice cuyabensis , versus entirely green and foliose as described for Philodice hoffmannseggii . The corollas of S. xinguensis form a stiff urceolate cup which is constricted over the ovary as in S. cuyabensis . We were not able to study the number of anthers or anther locules.

The thick, urceolate, non-involute corollas of S. cuyabensis are perhaps its most peculiar feature. Few species of Syngonanthus sensu strictu possess thickened corollas, and when so, they are not usually of this nature. However, in addition to S. xinguensis , they are also found in S. fenestratus Hensold (1991: 434) , a stem-dimorphic species of Venezuela and the upper Amazon basin. This species, though distinct in habit and more robust, also occurs in wet habitats, has involucral bracts green-striped along the midvein, and a very similar corolla morphology, especially of the pistillate flower. The staminate corollas are also urceolate but unlike the acutely lobed pistillate corollas, have a rounded, shallowly lobed upper margin ( Hensold 1991: fig. 7). In addition, in herbarium material of S. fenestratus , the pollen often appears pinkish-purple, as in S. cuyabensis . This seems to be an unusual feature as well, but pollen color, normally yellowish, has not been recognized as a character and has not been studied in the genus.

Syngonanthus anomalus ( Koernicke 1863: 458) Ruhland (1903: 267) , a floating-stem aquatic, and S. cowanii Moldenke (1953: 99) , another stem-dimorphic species of Venezuela, also have fleshy non-involute corollas, but these lack the distinctive urceolate shape of the other three species. All species here mentioned with non-involute corollas also have floral bracts.

At this time, it is not practical to assign a sectional placement to S. cuyabensis , S. xinguensis , or S. fenestratus , given that the traditional two sections of Syngonanthus are probably artificial and are currently under molecular study. However, given the diversity now contained within Syngonanthus , and the finding that the character historically used in generic definition of Philodice , monothecous anthers, is unstable, it is reasonable to transfer the single species to Syngonanthus .