Spigelia genuflexa Popovkin & Struwe, 2011

Popovkin, Alex V., Mathews, Katherine G., Santos, Jose Carlos Mendes, Molina, M. Carmen & Struwe, Lena, 2011, Spigelia genuflexa (Loganiaceae), a new geocarpic species from the Atlantic forest of northeastern Bahia, Brazil, PhytoKeys 6, pp. 47-56 : 48-50

Spigelia genuflexa Popovkin & Struwe sp. nov. Figs 1 2

Additional photos at Popovkin:

http://calphotos.berkeley.edu/cgi/img_query?where-taxon=Spigelia+sp.+nov.&where-lifeform=specimen_tag&rel-lifeform=ne&rel-taxon=begins+with&title_tag=Spigelia+sp.+nov.; http://bit.ly/io7bpT--2009-2011

Diagnosis.

Haec species Spigelia flemmingiana Cham. & Schltdl. similis, sed plantis brevioribus (1.5-25.0 vs. 17-50 cm), foliis parvis (0.6-2 × 0.2-0.5 cm vs. 2-9 × 1.4-2 cm) ellipticis vel ovatis (vs. lanceolatis), corollis brevioribus (0.4-0.8 vs. ca. 1 cm), inflorescentiis paucifloribus, et infrutescentiis nutantibus in maturitatem (vs. semper erectis) differt.

Similar to Spigelia flemmingiana Cham. & Schltdl. but shorter (1.5-25 cm vs. 17-50 cm tall), with smaller leaves (0.6-2 × 0.2-0.5 cm vs. 2-9 × 1.4-2 cm) that are elliptic to ovate (vs. lanceolate), shorter corollas (0.4-0.8 cm vs. ca. 1 cm), fewer-flowered inflorescences (up to 7 flowers vs. up to 38 flowers), and infructescences bending downward at maturity (vs. staying erect).

Type.

Brazil: Bahia: Entre Rios, Fazenda Rio do Negro, Residual stands of the Atlantic Forest. Restinga-type forest of the Rio do Negro valley, ca. 15 km southeast of Entre Rios, Atlantic forest, 12°01'S, 38°02'W, 150 m, 31 July 2009, A.V. Popovkin & J.C. Mendes 617 (holotype: HUEFS).

Description.

Annual herb, 1.5-25 cm tall. Roots fibrous, not very extensive. Stem branched at base, with reddish tint, with 4-6 prominent ribs decurrent from the leaf bases; interpetiolar stipules triangular, with abundant papillae on outside. Leaves opposite as well as 4 together higher up on the main branch under the inflorescence, 6-20 mm long, 2-5 mm wide, elliptic to ovate; secondary veins 4-6 pairs, arcuate, inconspicuous below and above, midrib raised below; base acute, with decurrent lamina; margin flat or slightly revolute, entire; apex obtuse; upper side with many short, transparent papilloid hairs, 0.1-0.3 mm long; lower side glabrous; petiole 1-2 mm long. Inflorescence variable, solitary (occasionally multiple), typically a one-sided cyme (rarely a simple cyme/dichasium or a single flower), unbranched, (1-)4-7-flowered, up to 28 mm long, without bracts or with 1-2 tiny bracts subtending flowers; peduncle 7-15 mm. Flowers actinomorphic, perfect, 5- (rarely 6-) merous. Calyx divided almost to base, green, persistent in fruit; lobes triangular, acuminate, 0.8-1.4 mm long, c. 0.3 mm wide, with slightly papillose margins. Corolla sympetalous, tubular, slightly widening towards mouth, 4-8 mm long, 2.5-3.0 mm wide at mouth, white with pink lobes, aestivation valvate with individual corolla lobes plicate in bud, lobes unfolded when open, closing after a short (8-hour) anthesis, later withering and deciduous; lobes triangular, 1.0-1.5 mm long, ca. 1 mm wide, erect, acute, with smooth margin. Stamens epipetalous and adnate to corolla up to middle of the tube, of equal length, included in corolla; filaments flattened; anthers 0.7-0.8 mm long, shallowly sagittate at base, truncate at apex. Ovary bicarpellate, bilocular, ovoid, ca. 0.4 mm tall, with truncate apex; style 3-6 mm long (including stigma), simple, articulated at 0.5-1.00 mm above the ovary, mostly dehiscent in fruit (except the persistent base); stigma simple, papillose, 'brush-like' at the height of the anthers. Fruit a bilobed capsule, 1.5-2 mm tall, 2-3 mm wide; dehiscing septicidally, loculicidally and circumscissilly, leaving behind on the rachis a persistent, boat-shaped base with pointed tips (' carpoatlas ' in Fernández Casas' (2003) terminology); light brown, warty to papillose; with ca. 0.5 mm tall style remnant. Seeds brown, round, reticulate surface when dry, ca. 0.7-1 mm in diameter.

Distribution.

This species is known from only two localities in northeastern Bahia (Brazil), about 30 km from the Atlantic coastline.

Ecology.

The species has been found on sandy,leaf litter- or moss-covered soil areas along the border of a tabuleiro forest. The diminutive flowers appear to be able to self, based on observations of cultivated material, with one to two flowers opening at one time. The anthesis begins early in the morning and ends in the afternoon of the same day. The arrangement and morphology of stamens and pistil, with anthers located closely to the central pistil with hairy upper part ( Figure 1 ), suggests that spatial closeness of flower parts may promote selfing, thus ensuring fruit set. Occasional tiny ant visitors have been observed entering the open flowers, though it is not entirely clear if they might be the pollinators.

Dispersal.

The geocarpy, i.e. weak geocarpy (depositors, in Hylander's [1929] terminology), of this species was initially observed on plants transplanted to a pot kept on a windowsill, allowing for daily/hourly observations. Two growth forms have been observed: one with inflorescences forming after the first three pairs of leaves are formed (usually, with a long internode between the first pair of leaves and subsequent two pairs), with the plant height at that stage of about 1 cm, and the other with inflorescences forming after four or five pairs of leaves and the plant reaching the height from 10 to 25 cm. The lower-forming inflorescences at the start of the fruit set would bend down to the soil, depositing the ripe fruit on the ground, while the higher-forming inflorescences would bend down noticeably but, because of the main stem height, wou ld be unable to touch the soil surface. Inflorescences with the fruit not set (a rare phenomenon) stay upright. Later observations of plants growing on moss-covered ground showed that the capsules are actually buried in the soft substrate ( Fig. 2G ).

Etymology.

The specific name refers to the sometimes repeated bending of its infructescence branches to the ground, figuratively evoking an image of the etiquette of genuflexion.

Preliminary conservation status.

The species is known from only a handful of collections from two restricted populations in a non-protected area (private land), and should therefore be assessed as Data Deficient for EOO and AOO, following IUCN (2001) 's criteria.

Phenology.

The species has been found flowering and fruiting from March to November during the local rainy season. It takes about 3-4 weeks from anthesis to fruit maturity. Living plants have not been observed from December to early March.

Specimens examined.

Brazil: Bahia: Entre Rios: Fazenda Rio do Negro, Residual stands of the Atlantic Forest. Restinga-type forest of the Rio do Negro valley, ca. 15 km southeast of Entre Rios, Atlantic forest, 12°01'S, 38°02'W, 150 m (topotypes), 3 June 2009, A.V. Popovkin 598 (HUEFS); ibid., 10 June 2009, A.V. Popovkin 602 (CHRB, NY); ibid., 15 July 2009, A.V. Popovkin 602A (CHRB, NY); ibid., 31 July 2009, A.V. Popovkin 617 (HUEFS); ibid., 27 May 2010, A.V. Popovkin 703 (HUEFS); ibid., 4 Sep 2010, A.V. Popovkin 744 (HUEFS); ibid., 18 January 2011, A.V. Popovkin 825 (HUEFS); ibid., 8 June 2011, A.V. Popovkin & J.C. Mendes 885 (HUEFS). Bahia: Entre Rios: Imbé, Atlantic forest, 12°05'S, 38°W, 135 m: 1 October 2010, A.V. Popovkin & J.C. Mendes 758 (HUEFS); 1 June 2011, A.V. Popovkin & J.C. Mendes 878 (HUEFS); 8 June 2011, A.V. Popovkin & J.C. Mendes 885 (HUEFS); 17 August 2011, A.V. Popovkin & J.C. Mendes 913 (HUEFS).

Figures

Figure 1. Spigelia genuflexa A-B Habit, showing inflorescences and geocarpic infructescenses, and close-up of apical part of leaf with apressed papilloid hairs C Close-up of node and internode, showing small triangular interpetiolar stipules D Flowers before and at anthesis E Close-up of flower at anthesis; note diminutive bract F Opened corolla with epipetalous stamens G Stamen inserted into corolla and introrse anther H Gynoecium inside papillose calyx, with hairy style (brush-type); older gynoecium, after style has dried and fallen off to the right I Geocarpic infructescence branch with one whole capsule (mitra-shaped, with small style remnant in center), and capsular base of the fruit that has dehisced, above it J Seed. Drawing by Bobbi Angell, based on A. V. Popovkin 602 and 602 A.

Figure 2. Spigelia genuflexa A Habit of mature plant B Flowers at anthesis and before opening. Note valvate and vertically folded petal lobes C Close-up of leaf with apressed papilloid hairs D Base of fruit after dehiscence (' carpoatlas') E Fruit before dehiscence F Whole plant with roots. Scale bar = 1 cm G Infructescence showing geocarpy. Photos by Alex Popovkin.