Dyckia pseudodelicata Büneker & Mariath, 2022

Büneker, Henrique Mallmann & Mariath, Jorge Ernesto De Araujo, 2022, Dyckia pseudodelicata, a new species of the D. selloa complex (Bromeliaceae, Pitcairnioideae) from Rio Grande do Sul, Brazil, Phytotaxa 550 (1), pp. 59-70 : 60-67

Dyckia pseudodelicata Büneker & Mariath , sp. nov.,

Figure 1A–D , 2A–J , and 3A–I .

Tantam habet haec species cum Dyckia delicata similitudinem ut primo intuitu foliis eandem diceret, nisi differt ramis inflorescentiae tenuibus (2–3.4 mm diam. vs. crassis, 4–5 mm diam.) et pluribus (usque 18 ramis vs. usque 7 ramis), floribus apicum ramorum subverticillatis (vs. laxe dispositis, numquam subverticillatis), floribus minoribus (1–1.2 cm vs. 1.4–2 cm longi), marginibus petalorum cum trichomibus triformibus (flabelliformia, uniseriata-capitata et dendritica vs. cum trichomibus uniformibus: filiformia aut unicellularia, vel sine trichomibus), lobis stigmatis minoribus in anthesem (1–1.4 mm vs. 2–2.5 mm longi), et seminibus rudimentis suberectis, in duas series per loculum dispositis (vs. patentibus, in 2–4 series per loculum).

Type: — BRAZIL. Rio Grande do Sul: Jari, encosta rochosa próxima ao arroio Toropi-mirim , 17 January 2020, H. M. Büneker 913, L. Witeck & J. C. Silva (holotype: ICN!, isotypes: SMDB!, RB!) .

Herb saxicolous, rhizomatous, 0.47–1.19 m tall when flowering; rosette 15–29 cm in diameter, symmetrical. Leaves 50–108, the inner ones suberect, the outer ones patent to reflexed; blade 7–18 × 1.1–1.9 cm, arched, narrowly triangular, flexible, adaxial surface convex, purplish-cinereous, densely lepidote, abaxial face convex, longitudinally veinedstriate, cinereous, lepidote between the veins, margins densely spinose-serrate, apex terminating in a rigid, pungent spine; spines conspicuous, those of the blades margins narrowly triangular, patent or subpatent-retrorse, sometimes hooked at the apex, flexible, lepidote, pinkish-white at the base, whitish at the median portion and at the apex, apex not pungent. Inflorescence axillar, erect or suberect; peduncle 19–53 cm long, green to purple, devoid of trichomes and pruinose; peduncle bracts polystichous, those of the median portion 1.5–2.6 × 0.5–1 cm, stramineous, shorter than the internodes; fertile portion of inflorescence composed, once-branched, 28–50 cm long; first order bracts similar to peduncle bracts, 0.5–1.3 cm long; branches 4–18 in number, suberect to patent, 9–17 cm long, 2–3.7 mm diam., greenish to purple, devoid of trichomes, pruinose; floral bracts 1.5–3 × 1–1.5 mm, oval-triangular, base green, median and apical region soon dry, yellowish, the apex brown, attenuate-acuminate, ecarinate, devoid of trichomes, pruinose, shorter than the sepals. Flowers 1–1.2 cm long, inconspicuously pedicellate, patent, polystichous or subverticillate; pedicels ca. 0.7 mm long, green, pruinose; sepals 2.1–2.5 × 2–2.5 mm, suborbicular, apex obtuse to rounded, green at the base, yellow at the apex, slightly carinate, devoid of trichomes and pruinose on the abaxial surface, margins with very sparse dendritic trichomes or glabrous; petals 8–9 × 3.5–4 mm, not unguiculate, erect to incurving toward the apex, oblanceolate, yellow, glabrous on both surfaces, proximal margins exhibit sparse dendritic trichomes, median margins plicate, exhibit densely arranged uniseriate-capitate or dendritic trichomes, distally margins exhibit narrowtriangular multicellular emergences giving the margins a torn appearance and also exhibit white-hyaline trichomes densely arranged, usually alternating between uniseriate-capitate and flabelliform, apex round-cucullate; dendritic trichomes, those of the petal proximal margins with foot with 1–2 living cells, stalk uniseriate with 3–6 cells usually dead or living basal cells, little elongated, region of branching little expanded, with 2–7 branches formed by strongly elongate, dead cells; those of the petal median margins with foot with 1–2 living cells, stalk uniseriate with 2–6 slightly elongate dead cells, branching region expanded with (2–)3–6 anticlinally arranged cells, followed by 3–9 branches formed by elongate dead cells; uniseriate-capitate trichomes, those of the petal median margins with 3–6 living cells; those distal petal margins with 3–8 living cells; flabelliform trichomes of the petal distal margins with foot of 1–2 living cells, stalk uniseriate with 1–2(–3) hardly elongate dead cells, or live basal cells, expanded region with 3–7 anticlinally arranged dead cells, followed by (4–)6–15 branches formed by elongate dead cells; stamens included in the corolla during opening of the thecae, later becoming exserted; filament 7–9 mm long, free above the short hypantium, the antepetalous ones adnate to the petals for ca. 0.3 mm; anther 1.5–2 mm long, not rostrate; sporangia unequal; pistil 0.9–1 cm long; ovary 1.5–2 × 1.2–1.5 mm, green; locules pauciovulate; ovules suberectly positioned, inserted in two rows per locule; style 6–7 mm long, yellowish-white; stigma conduplicate, stigmatic lobes 1–1.4 mm long, suberect to erect, yellow. Capsule ovoid, dark brown when mature. Seeds oblanceoloid.

Etymology: —The specific epithet “pseudodelicata” refers to the vegetative similarity between the new species and D. delicata . The new species was not flowering when first collected and was believed to be D. delicata . However, significant morphological differences found after checking its inflorescences revealed it to be a new species, which we decided to call “false” D. delicata .

Distribution and Habitat: —The new species occurs as a saxicolous heliophyte on a rocky basaltic escarpment facing north, near the Toropi-mirim stream. Only one population of the species was located in the municipality of Jari, state of Rio Grande do Sul, southern Brazil. Several similar environments occur in the region, and so it is possible that there are further populations of the species. Some similar environments were found within a ca. 4 km radius around the known population of D. pseudodelicata , but only populations of D. selloa (on a rocky vertical escarpment) and D. dusenii Smith (1932: 6) (on a hillside with shallow litholic soil) were found. Two individuals observed in the population of D. pseudodelicata were probably natural hybrids between D. pseudodelicata and D. dusenii , and probable hybrids of D. selloa and D. pseudodelicata were observed in vicinity to D. selloa .

We estimate that the population of D. pseudodelicata has about 200 adult individuals. The population size is being reduced due to habitat loss, as pioneer tree species, mainly Helietta apiculata Bentham (1882: 67) (Rutaceae) , are settling in the site and decreasing the availability of light. The natural reduction of the habitat of the species, and of the relictual xerophyte community to which it is associated, is worrying as some rare species of Cactaceae (i.e., Eriocephala magnifica ( Ritter 1966: 50) Guiggi (2012: 6) , Notocactus horstii f. purpureus ( Ritter 1970: 109) Herm (1993: 64) , and N. oxycostatus f. securituberculatus ( Ritter 1979: 169) Gerloff (1993: 93)) occur in association with it, in addition to other species characteristic of this environment (e.g. Sinningia sellovii ( Martius 1829: 36) Wiehler (1978: 72) , S. macrostachya ( Lindley 1828: t. 1202) Chautems (1990: 386) ( Gesneriaceae ), Habranthus aff. pedunculosus Herbert (1837: 161) (Amaryllidaceae) , and Hatschbachiella cf. tweedieana (Hooker & Arnott 1835[1836]: 242) King & Robinson (1972: 394) ( Asteraceae )).

The vegetational physiognomy in which the xerophytic relict is inserted, and where the new species occurs, is a transitional region between the Pampa grasslands and the seasonal forest of the Atlantic Forest domain. This transition is located at the edge of the Southern Brazilian Plateau, in the central region of the state of Rio Grande do Sul, in the hydrographic basin of the Toropi-mirim stream, a tributary of the Toropi river. Taxonomic studies of plants in this region have revealed a significant number of endemic and rare ( Marchiori et al. 2014; Büneker & Witeck-Neto 2016) or new species over the last two decades ( Menezes 2009; Soares & Longhi 2011; Büneker et al. 2013, 2015a, 2017, 2018; Deble & Alvez 2013; Coelho & Miotto 2017; Silveira et al. 2019; Figueira & Schindler 2021).

Observations and discussion:— The new species is morphologically similar to D. delicata , mainly due to its vegetative aspect ( Figs. 1A–B , and 2A–E, K–O ), which is unique among the species of the D. selloa complex, as both species have leaf blades that resemble chilopods of the genus Scolopendra Linnaeus (1758: 637) . The leaf blades are succulent, arched, reflexed, both faces are convex, and also possess dense conspicuous trichomes ( Fig. 2E and O ) and densely spiny margins with highly developed, although flexible and not pungent, spines ( Fig. 2A–D, K–N ). These vegetative characteristics have made D. delicata highly appreciated and widespread among gardeners and collectors of ornamental succulent plants ( Sachs 2011) and bestow D. pseudodelicata with the same potential.

Dyckia delicata possesses a series of singularities among the species of the D. selloa complex with regards to the morphology of its inflorescences and flowers. The sparsely branched architecture of the inflorescence, being simple or compound, once-branched, with branches only at the base of the fertile portion (when compound), robust branches, relatively large flowers with spiraled stigmatic lobes in pre-anthesis, and patent ovules positioned in relation to the longitudinal axis of the ovary, are features that are absent from most of the remaining species of the D. selloa complex but widely observed among other Dyckia species. Despite the great morphological similarity between D. delicata and D. pseudodelicata , the latter does not possess the morphological singularities mentioned above, having instead various flower and inflorescence character states typical of most species of the D. selloa complex.

Dyckia pseudodelicata basically differs from D. delicata in the fertile aspect ( Tab. 1 ) by having an inflorescence with thin (2–3.4 mm vs. robust, 4–5 mm diam. [ Fig. 2F and P ]) and numerous first order branches (up to 18 [ Fig. 1D ] vs. absent or up to 7), flowers in the apical region of the branches subverticillate (vs. flowers spaced [ Fig. 2H and R ]) and smaller flowers (1–1.2 cm vs. 1.4–2 cm in length [ Fig. 2G and Q ]), anthers without a rostrum at the apex (vs. with a rostrum [ Fig. 2I and S ]) and thecae with sporangia of different lengths (vs. equal [ Fig. 2I and S ]), stigmatic lobes that are erect (vs. spiraled) at anthesis and smaller (1–1.4 mm vs. 2–2.5 mm in length [ Fig. 2J and T ]). Some morphological characters of Dyckia have been little explored regarding their use in taxonomy, probably because they are inconspicuous, impractical for identification purposes and difficult to observe with the naked eye and/or in herborized material. Nonetheless, here we explore two unusual characters that proved to differentiate D. delicata and D. pseudodelicata : the morphology of the trichomes on the margins of the petals and the position of ovules in relation to the longitudinal axis of the ovary and their disposition in the placenta.

The margins of the upper portion of the petals of both species possess multicellular, narrowly triangular emergences; however, they are more numerous in D. pseudodelicata , especially in the cucullate region of the apex, giving the margin a torn appearance. The petal margins of D. delicata are straighter and the emergences are concentrated only in the margins of the apex ( Fig. 3J and L ). The margins of the petals of D. delicata have few trichomes, which usually occur in greater numbers at the apex and are filiform, unicellular and not very elongate ( Fig. 3K and M ). In contrast, D. pseudodelicata has numerous trichomes in the margins of the petals and possesses three patterns of morphology and distribution: well-developed, dendritic, sparse in the proximal portion of the margins ( Fig. 3A–B and D ); uniseriate-capitate, multicellular, sparse (and not very numerous) in the distal region of the margins and apex ( Fig. 3F ); and alternated by very numerous flabelliform trichomes ( Fig. 3E ), generally well developed, densely arranged in the margins near the apex ( Fig. 3C ).

The morphology and presence of these trichomes is an important diagnostic character to be analyzed in the context of the D. selloa complex, as it seems to be conserved among individuals of the same species and generally distinct between species. These trichomes are present in almost all species of the D. selloa complex, occurring in the margins and abaxial surfaces of perianth parts. However, they have been poorly characterized for most Dyckia species, especially those of the petals, which are absent in most species not belonging to the D. selloa complex ( Carvalho et al. 2017; Büneker et al. 2020, Büneker 2021). Trichomes like those of the petals of species of the D. selloa complex can also be observed in species of the D. ferruginea complex ( D. excelsa Leme (1993: 6) , D. ferruginea Mez (1896: 533) , D. insignis Hassler (1919: 316) , D. lymaniana ( Pereira & Martinelli 1982: 252) Forzza (in Gomes-Da-Silva, Santos-Silva & Forzza 2019: 486), and D. splendida Pereira & Gouda (2018: 137)) . Species of the D. ferruginea complex appear related to those of the D. selloa complex in the phylogenies of Krapp et al. (2014) and Pinangé et al. (2017), and the presence and similarity of petal trichomes in the species of these two complexes may indicative the degree of relationship between them, even though they appear very distinguished. Thus, these trichomes have great potential to be observed in the future under evolutionary, phylogenetic, morphological and functional aspects.

The position of the ovules in relation to the longitudinal axis of the ovary and their disposition in the placenta (number of rows) have been little studied in Dyckia and are not covered in detail in the descriptive taxonomic literature. Mez (1935) reports that Prionophyllum (genus name, currently synonymous with Dyckia , which is equivalent to the D. selloa complex) has few ovules and presents an illustration with the longitudinal section of the ovary of D. selloa in which the ovules are suberect in relation to the axis of the ovary and inserted at the axillary base of the carpel. Dyckia pseudodelicata , like D. selloa , possesses ovules that are suberect in relation to the longitudinal axis of the ovary (that is, oriented obliquely to the placentation region) and in a reduced number, which was also verified for most species of the D. selloa complex. One of the exceptions is D. delicata , which possesses ovules that are patent in relation to the longitudinal axis of the ovary and in a considerably larger number, as was usually verified for species of Dyckia that do not belong to the complex.

We hypothesize that the suberect position for the ovule was a response to carpel size reduction in the common ancestor of the D. selloa complex, if the D. selloa complex represents an evolutionary lineage. This reduction and suberect position of the ovule has yet to be widely verified among other lineages of the xeric Pitcairnioideae . However, in the earlier divergent lineages of the xeric Pitcairnioideae , such as those that compose Encholirium (having as references the phylogenies of Krapp et al. (2014) and Pinangé et al. (2017)), the locules of the carpels are relatively large and the position and disposition of ovules of most species are identical to that observed in species of Dyckia that do not belong to the D. selloa complex. These characters, however, need to be further investigated. A further increase in carpel size during evolution, as in D. delicata , could be interpreted as a reversal to the ancestral state of the xeric Pitcairnioideae . With greater availability of locular space, the position of the ovules in relation to the longitudinal axis of the ovary became clear again. Thus, the disposition of ovules in a greater number of rows may have arisen in association with this larger space, as observed in D. delicata .

The ovules of D. pseudodelicata are disposed in two rows per locule, with one row per placental attachment line ( Fig. 3G and H ), as is the case for most of the species of Dyckia studied to date. On the other hand, D. delicata may have ovules disposed in 2–4 rows per locule, with one or two rows per placental attachment line ( Fig. 3N and O ). Analysis of Endress’s (2011) review of the diversity, development and evolution of angiosperm ovules reveals that both ovule position in relation to the longitudinal axis of the ovary and ovule arrangement (number of rows) seem to be related to the proportion of available locular space and ovule size, ovule number and direction of ovule initiation sequence in placentae. Kuhn et al. (2020) reported that ovules arranged in a few rows per placental attachment line is an ancestral character in Bromeliaceae . Transitions toward many ovule rows occurred at least twice at the base of a clade, including all genera of Tillandsioideae , except Catopsis , on the one hand, and among Puyoideae and Bromelioideae on the other hand. These transitions are followed by at least three reversals in Tillandsioideae and one, but perhaps more, in Bromelioideae .A transition from many towards lots ovule rows per each placental attachment line is observed at the base of the Werauhia clade within Tillandsioideae , while another transition from few to many ovule rows occurred at the base of the Pitcairnia clade within Pitcairnioideae .

Despite these differences in the position and disposition of ovules between D. delicata and D. pseudodelicata , their seeds are morphologically similar ( Fig. 3I and P ), being oblanceoloid as for other species of Dyckia belonging to the complex and possessing a chalazal appendix which constitutes a poorly developed wing (vs. well developed for the rest of Dyckia ). The anatomy, number, position in relation to the longitudinal axis of the ovary and disposition of ovules are characters to be investigated more widely in the xeric Pitcairnioideae as they seem to have taxonomic importance as diagnostic characters and may be directly related to the unique morphology of the seeds of the D. selloa complex. They are oblanceoloid with a poorly developed chalazal appendix (vs. flated with developed chalazal appendix forming a subfalciform wing in most Dyckia l.s.), a characteristic that appears to be a synapomorphy of the complex. Furthermore, the study of embryological characters can be an important tool for evolutionary analysis and help in phylogenetic reconstructions.

Additional Specimen Examined (paratype):— BRAZIL. Rio Grande do Sul: Jari, encosta rochosa próxima ao arroio Toropi-mirim , 3 August 2017, floresceu em cultivo em January 2020, H. M. Büneker 635 et al. ( RB) .

Figures

FIGURE 1. A–D. Dyckia pseudodelicata (A H.M. Büneker 635 et al.; B–D Büneker 913 et al.) in habitat. A. Vegetative habit. B. Leaves detail. C. Fertile habit. D. Detail of apical portion of the inflorescence.

FIGURE 2. A–J. Dyckia pseudodelicata (Büneker 913 et al.), K–T. Dyckia delicata (Büneker 395 et al.). A and K. Median region of leaf adaxial face. B and L. Median region of leaf abaxial face. C and M. Detail of adaxial face leaf margin with spines. D and N. Detail of abaxial face leaf margin with spines. E and O. Details of trichomes on the surface of the leaf adaxial surface. F and P. Main axis of the inflorescence. G and Q. Detail of flower in anthesis. H and R. Detail of buds. I and S. Anther. J and T. Stigma.

FIGURE 3. A–I. Dyckia pseudodelicata (Büneker 913 et al.), J–O. Dyckia delicata (Büneker 395 et al.). A–F and J–M. Petal margin. A. Trichomes of the proximal margin. B. Trichomes of median margin. C. Trichomes of the distal margin. D. Dendritic trichome on DIC. E. Flabelliform trichome on DIC. F. Uniseriate-capitate trichome (left) and flabelliform trichome (right) on DIC. J. Emergences of the distal margin. K. Unicellular trichomes of the apical region. L. Emergences on DIC. M. Unicellular filiform trichomes on DIC. G and N. Transverse section of the median region of ovary. H and O. Detail of transverse section of median region of ovary, where two rows of ovules can be seen in H and four in O. I and P. Seed. E, G, H, L, M, N and O. Stained with Safranin. D and F. Stained with Toluidine Blue.