Utricularia biceps Gonella & Baleeiro, 2018

Gonella, Paulo Minatel & Baleeiro, Paulo César, 2018, Utricularia biceps (Lentibulariaceae), a new carnivorous species endemic to the campos rupestres of Brazil, Phytotaxa 376 (5), pp. 214-222 : 215-219

Utricularia biceps Gonella & Baleeiro , sp. nov. ( Figures 1 and 2 )

Type — BRAZIL. Minas Gerais, Botumirim, Rio do Peixe, 10 February 2011, Gonella et al. 376 (holotype SPF!).

Diagnosis —Species most similar to Utricularia tricolor A.St.-Hil., but distinguished by the corolla lower lip with a prominent bilobed crest with tuberculate texture on the gibbose palate, a spur with apex swollen and bifid, about the same length of the lower lip, the upper lip of the stigma with ciliate apex, ovoid seeds, and with trap appendages emerging from a flat extension in the apical portion of the trap mouth.

Description —Medium-sized perennial, terrestrial. Rhizoids few, filiform, with simple short branches, up to 1 cm long, c. 0.2 mm thick. Stolons few, filiform, sparsely branched, up to 6 cm long, c. 0.2 mm thick. Leaves few, 1–4 rosulate at the base of the peduncle, petiolate, lamina obovate with apex rounded, green to red in color, with numerous anastomosing nerves, 5–20 × 1.5–4.0 mm. Traps numerous on the stolons, broadly ovoid, on stalk of c. 1.5 mm length, c. 1 × 1 mm, mouth basal, with a pair of appendages emerging from a flat extension in the apical portion of the trap mouth, apex of appendages acute, distal end of the stalk with a distinct swelling, inner surfaces of appendages and the distal end of the stalk densely covered with fine, distally inflexed, gland-tipped hairs. Inflorescence a raceme, erect, simple, solitary, 12.0– 31.5 cm long; peduncle filiform, terete, glabrous, 0.5–0.8 mm thick, deep red in color. Scales , bracts and bracteoles basifixed and single-nerved. Scales few, ovate-deltoid, with apex acute, 0.6–1.2 mm long. Bracts ovate-deltoid, with apex acute, 1.0–1.2 × 0.3–0.5 mm. Bracteoles linear-subulate, slightly shorter than and basally connate for half to 2/3 of length to the bract, with apex acute, 0.8–1 × 0.1–0.2 mm. Flowers 2–7; pedicel ascending, filiform, terete, 4–15 mm long (longer towards the base of the inflorescence), c. 0.2 mm in diam. Calyx lobes unequal, upper lobe longer than the lower lobe, glabrous, with few simple parallel nerves, red to greenish-red in color; upper lobe broadly ovate with apex rounded, strongly convex, 2.0–2.2 × 1.5–1.8 mm, firm in texture with a narrow hyaline margin; lower lobe convex, ovoid, with apex sub-acute or minutely bifid, 1.7–2.0 × 1.5–1.6 mm. Corolla violet, with yellow-orange crest at the base of the lower lip, minutely papillose, 8–10 mm long; upper lip oblong-ovate 3–4 × 3 mm, apex rounded; lower lip transversally elliptic, shallowly 3 lobed, with a prominent yellow-orange bilobed crest at the palate with tuberculate texture, 5.5–7.0 × c. 9 mm; spur cylindrical, narrow at the base and swollen at the mid-apex, apex bifid, slightly shorter than or equal in length to the lower lip, c. 2 mm in diam., 5–6 mm long. Filaments curved, c. 0.7 mm long, the anther thecae subdistinct, anther c. 0.7 × 0.3 mm. Ovary globose, glandular, 0.7 mm long; style short, 0.3 mm long; stigma bilabiate, lower lip semicircular, 0.5 mm long, with apex ciliate, upper lip truncate, 0.2 mm long. Capsule globose, to 2 mm in diam., shorter than the calyx lobes, dorsiventrally bivalvate. Seeds ovoid, reticulated in a helical arrangement relative to the longer axis of the seed, testa cells elongate, 0.35 × 0.20 mm.

Additional specimens examined (paratypes) — BRAZIL. Minas Gerais, Botumirim, Rio do Peixe, 06 September 2011, Gonella et al. 466 ( SPF) ; 18 July 2015, Rohrbacher 15 ( SPF) .

Etymology —from the Latin biceps (two-headed), referring to the most remarkable characteristics of the species, the crest on the palate with two protruded lobes, and also the spur with bifid apex ( Figs. 1E,F ; 2E–G ).

Phenology —The species was collected with flowers in February and July and flowers and fruits in September. In cultivation, the species flowers in the spring and fall, but no seed production was observed (C. Rohrbacher, pers.com.).

Distribution and habitat — Utricularia biceps is only known from a single location, where it grows on the margin of a perennial river on islands of vegetation over quartzitic rocks or on cracks of the same rock, in sandy soil with organic matter ( Fig. 2A, D ). It was only observed growing on the north-facing margin of the river, at elevations around 790 m.

The species is sympatric with the white and the lilac flowered forms of U. amethystina Salzm. ex Saint-Hilaire & Girard (1838: 870) , U. tricolor Saint-Hilaire (1833: 418) , U. subulata Linnaeus (1753: 18) , U. nana Saint-Hilaire & Girard (1838: 869) , U. nervosa Weber ex Benjamin in Martius (1847: 247), U. gibba Linnaeus (1753: 18) , U. tenuissima Tutin (1934: 334) , U. purpureocaerulea Saint-Hilaire & Girard (1838: 869) , Genlisea repens Benjamin in Martius (1847: 254), G. aurea Saint-Hilaire (1833: 429) var. minor ( Saint-Hilaire 1833: 430) Fleischmann (2012: 525) and several Drosera spp. ( Droseraceae ).

Conservation status —Critically Endangered (CR B2abiii). Utricularia biceps presents an AOO (area of occurrence) equal to 4 km 2, being considered critically endangered based on the IUCN criterion “AOO less than 10 km 2, number of locations equal to one and continuing decline of the quality of the habitat”. The occurrence of this species lies within a recently created conservation unit, the Botumirim State Park (Decreto No 302, 04 July 2018). However, the area where the species was found is used by tourists as a recreational spot, due to its crystal clear waters and scenic landscapes ( Fig. 2A ). Incorrect management of the recreational use of this area could pose a threat through trampling and pollution of soil and water, potentially having a negative impact on the fragile habitat in the short term.

Taxonomic notes — Utricularia biceps belongs to Utricularia sect. Foliosa Kamiénsky (1891: 120) , characterized by the traps broadly ovate with a basal mouth and two dorsal appendages, and capsule dorsiventrally bivalvate ( Taylor 1989). The species of the section can be further recognized by the bracts and bracteoles proximally connated. The section traditionally included three species, but U. amethystina is clearly a species complex composed by numerous taxa, which were tentatively united by Taylor (1989) under that name justified by the presence of intermediate forms between the morphotypes.A morphometric approach, however, has corroborated the segregation of synonyms and new species currently under U. amethystina ( Baleeiro et al. 2016) , and the group is currently under taxonomic revision by Baleeiro et al. (in prep.). All accepted taxa and synonyms within this complex were analyzed and none represent the newly described taxon.

Molecular phylogenetic studies suggested the merger of a paraphyletic U. sect. Psyllosperma Taylor (1986: 8) within a more broadly circumscribed U. sect. Foliosa ( Jobson et al. 2003; Müller & Borsch 2005). This hypothesis, however, was based on analysis with insufficient taxon sampling and also on the position of a misidentified voucher of U. huntii Taylor (1986: 8) , which actually represents a taxon in the U. amethystina complex [Rivadavia-Lopes & Sato 1000 (SPF!)]. Unpublished phylogenetic studies (Baleeiro et al. in prep.), based on a broader taxon sampling, support a monophyletic U. sect. Psyllosperma, sister to a monophyletic U. sect. Foliosa, a phylogenetic placement we follow here.

Utricularia biceps grows sympatric with two other species of U. sect. Foliosa: U. tricolor and two distinctive taxa currently assigned as morphotypes of a variable U. amethystina s.l. (sensu Taylor 1989). Like U. biceps , U. tricolor also presents transversally elliptic and shallowly 3-lobed corolla lower lobe, but can be easily distinguished by the conical spur, which is much longer than the lower lip and with a single, acute apex (as in all other species of the section). The sympatric morphotypes of U. amethystina can be distinguished by the deeply 3-lobed lower lip with a long conical spur (lilac form) or by the white corolla color, with a very short lower lip, broadly conical spur, and densely glandular-pilose indumentum on spur and calyx (white form). Furthermore, these two species lack the tuberculate crest on the palate, having only an inflated palate with papillose texture.

The two projections with tuberculate texture of U. biceps are a novel character described for U. sect. Foliosa. This is similarly observed in U. geminiloba Benjamin in Martius (1847: 242) and most remarkably in U. nephrophylla Benjamin in Martius (1847: 247) of U. sect. Orchidioides A.DC. in DeCandolle (1844: 23) (U. sect. Iperua Taylor (1986: 10) sensu Taylor 1989), which present a swelled bilobed palate, each lobe with a rugose crest.

The upper lip of the stigma with ciliate margin is also a new character for U. sect. Foliosa. Although not cited in the description, Taylor (1989) illustrates a pilose stigma for U. hispida Lamarck (1791: 50) , of U. sect. Psyllosperma, but in the illustration, the trichomes are distributed along the surface of the upper lip and not exclusively on the margin, as in U. biceps .

Unlike all other species of U. sect. Foliosa, the two appendages of the trap originate from a flat extension in the apical portion of the mouth ( Fig. 1B ), while in all other species the appendages are free from the base, representing another new character among the taxa of this section.

Seeds of U. biceps are very distinct from those of the other species of U. sect. Foliosa, presenting an ovoid shape ( Fig. 1J ), while seeds are narrowly cylindrical in U. tricolor and U. tridentata Sylvén (1909: 28) , and obliquely ovoid to narrowly cylindrical in the U. amethystina complex. It shares with U. amethystina the rows of testa cells markedly helically arranged relative to the longer axis of the seed. The seeds studied were harvested from unripe fruits from a herbarium specimen, which could explain the disparate seed shape observed. No seeds were produced in cultivation (C.Rohrbacher, pers.comm.).

Within U. sect. Foliosa, U. biceps presents the most restricted distribution, being microendemic to the Rio do Peixe area, in the municipality of Botumirim. The other three taxa included under U. sect. Foliosa in the circumscription of Taylor (1989) are widely distributed across South America and even Central and North America in the case of U. amethystina . Utricularia tricolor is widely distributed across South America, from Argentina to Venezuela, whereas U tridentata is restricted to southeastern South America, in the Brazilian states of Rio Grande do Sul, Santa Catarina, Paraná, and Rio de Janeiro, as well as Uruguay and Argentina ( Taylor 1989; Flora of Brazil 2020 under construction). On the other hand, in the broad circumscription of Taylor (1989), U. amethystina is widely distributed across tropical and sub-tropical America, from Florida in the United States to São Paulo, in southeastern Brazil. Such a wide distribution of U. amethystina , however, may be a result of its broad circumscription, including a wide range of polymorphism ( Taylor 1989). Baleeiro et al. (2016) started to dissect this species complex using a morphometric approach and showed that some of the taxa synonymized under U. amethystina may be resurrected and even undescribed species are hidden under this name.

Figures

FIGURE 1. Utricularia biceps. A, habit. B, utricle, side view. C, bract and bracteoles. D, calyx. E, corolla, front view. F, spur. G, stamen. H, gynoecium. I, fruit, side view. J, seed. A–H based on the holotype; I–J based on Gonella et al. 466. Illustration by PMG.

FIGURE 2. Utricularia biceps. A, general view of the habitat at Rio do Peixe, Botumirim. B, inflorescence. C, immature fruit, side view. D, leaves and inflorescence bases. E, flower, front view. F, flower, side view, highlighting the projected bilobed crest on the palate with tuberculate texture. G, flower seen from below, highlighting the spur with bifid apex (top center), and dorsal sepal seen from above (bottom right). All by PMG.