Anisotes pulchellus (Benoist) T.F. Daniel, Letsara & Rakotonas, 2019

Daniel, Thomas F., Letsara, Rokiman & Rakotonasolo, Franck, 2019, Incorporation of Danguya into Anisotes (Acanthaceae: Justicieae), a New Combination, and Lectotypification of D. pulchella, Proceedings of the California Academy of Sciences 66 (2), pp. 51-59 : 53-58

Anisotes pulchellus (Benoist) T.F. Daniel, Letsara & Rakotonas , comb. nov.

Danguya pulchella Benoist, Bull. Soc. Bot. France 76: 1038. 1930 (“1929”).

TYPE.— MADAGASCAR. Mahajanga: Tampoketsa au dessus de Mahatsinjo , [ca. 17°45′00″S, 047°01′00″E], 1600 m, près du bois, IV-1925 (flr), H. Perrier de la Bâthie 17238 (lectotype, designated here: P!-barcode P00089775 ; isolectotype: P!-barcode P00089776 ) .

Shrubs to 2 m tall. Young stems subquadrate, evenly and usually densely pubescent with straight and erect to downward pointing or flexuose or retrorsely curved eglandular trichomes 0.05–0.4 mm long. Leaves petiolate, petioles 5–33 mm long, blades ovate to elliptic, 18–86 mm long, 12–42 mm wide, 1.3–2.2 (-3.3) times longer than wide, rounded to subacute (to acuminate) at apex, cordate to rounded at base, adaxial surface pubescent with mostly antrorse to antrorsely appressed eglandular trichomes (these sometimes sparse and restricted to major veins), abaxial surface more densely pubescent (especially along major veins) with antrorse to antrorsely appressed eglandular trichomes, margin entire and ciliate. Inflorescence of pedunculate spikes from leaf axils, peduncles 4–24 mm long, pubescent like young stems, spikes 1 (–2) per axil, alternate or opposite at nodes, (13–) 20–43 mm long (excluding peduncle and flowers), 11–23 mm in diameter near midspike (measured flat and excluding flowers), rachis not visible, pubescent with antrorse eglandular trichomes to 0.3 mm long and with an inconspicuous understory of erect subsessile to stipitate glandular trichomes to 0.05 mm long. Bracts red-maroon (at least along margin and distally), spirally arranged on rachis, ± spatulate (i.e., proximally stalked and abruptly ovate to broadly elliptic to subcircular distally), 10–19 mm long and 3.5–12 mm wide (sometimes with smaller and often green sterile bracts at base of spike), apiculate at apex with apiculum to 1.9 mm long, abaxially venose, pubescent like rachis, prominently 5–7-veined from base, basal stalk infolding and partially enveloping basal portion of bracteoles and calyx. Bracteoles lanceolate to lance-linear to lance-elliptic, 4–5 mm long, 0.5–0.8 mm wide, abaxially pubescent like rachis. Calyx 8–11 mm long, abaxially pubescent like rachis, 4- or 5-lobed, lobes with 2 pairs fused for much of their length forming 2 apically 2-lobed segments and the fifth (posterior?) lobe greatly reduced in size or absent, fused segments 5–9.5 mm long with apical lobes 0.6–6 mm long, reduced 5th lobe (when present) triangular-lanceolate to lanceolate, 2–3 mm long, 0.4–0.5 mm wide. Corolla red-maroon, 30–37 mm long, conspicuously arched, externally pubescent with erect to flexuose eglandular trichomes to 0.8 mm long and with a ± conspicuous understory of stipitate glandular trichomes less than 0.1 mm long, tube 14–16 mm long, upper lip 13–21 mm long, internally rugulate, apically entire, lower lip recoiled, 13–21 mm long, apically 3-lobed, lobes 2.5 mm long, 0.5–1.5 mm wide. Stamens 15–21 mm long, filaments glabrous distally and sparsely pubescent with eglandular trichomes proximally, thecae greenish white, subparallel to subsagittate, unequally inserted but overlapping, 2.5–3.3 mm long, subequal in size, glabrous, upper theca with a basal appendage 0.1–0.2 mm long, lower theca with a basal appendage 0.3–0.4 mm long. Pollen (see discussion) globose-elliptic (i.e., longer E:shorter E> 1 but ˂ 1.5), 2-colporate, 4-pseudocolpate, colpi extending to near poles, pseudocolpi equaling (or slightly shorter than) colpi, colpi and pseudocolpi microverrucate to microgemmate, interapertural exine ± bireticulate, P = 37–45 µm, E (apertural views) = 22–25 µm, E (interapertural view) = 19 µm, P:E (apertural view) = 1.68–1.8, P:E (interapertural view) = 2.05, E (apertural view):E (interapertural view) = 1.16–1.32. Style 27–32 mm long, sparsely pubescent with eglandular trichomes (except near apex), stigma 0.1 mm long, inconspicuously and unequally 2-lobed. Capsule 9.5–11 mm long, glabrous, retinacula and placentae not elastically rising; seeds (immature) 1.2–1.5 mm diam., surface pubescent with papilla-like trichomes.

PHENOLOGY.— Flowering: March– November; fruiting: November.

DISTRIBUTION AND HABITAT.— Central Madagascar (northern Antananarivo and southeastern to east-central Mahajanga; Fig. 2 ); plants occur in remnant or gallery forests at elevations of 1200–1600 meters.

ILLUSTRATIONS.— Figures 1 , 3.

CONSERVATION.— A preliminary conservation assessment based on IUCN (2017) criteria using GeoCat (2019) calculations was performed for Anisotes pulchellus using the locality and collection information provided herein. An EOO of 6,042 km 2 and an AOO (based on 2 km 2 grid) of 28 km 2 were calculated for the species. No protected lands are currently within the EOO; however, the Réserve Spéciale d'Ambohitantely lies adjacent to (but outside of) its southeastern boundary. Two collections of the species are from the Vohombohitra massif, a region known for the richness of precious stones found there, and where the local population partakes in the mining of these stones, gathering of wood for heating and construction purposes, and agricultural activities ( Ralainaorina 2016). Indeed, Ralainaorina (2016) specifically notes that the vegetation of Vohombohitra continues to lose its floristic richness due to these and other anthropogenic pressures (e.g., brush fires). Collection sites to the west of Vohombohitra, including the type locale, occur in small forest fragments that have been and continue to be impacted by burning (to clear forest for grazing land) and timber cutting ( Ratsirarson et al. 2003). These sites are treated as a second location based on the threat of forest clearing. Humbert 17981 occurs at the northeastern-most extent of the species' distribution, and it appears to occur in the western edge of the humid eastern escarpment forest in northern Madagascar. No threat is currently known for that site. Given these threats and an inferred continuing decline in the numbers of plants and their habitats based on the continuation of the threats, we propose a preliminary assessment of endangered (EN) for this species (B2(a, biii)).

TYPIFICATION.— In the protologue, Benoist (1930) listed two collections (numbers 17238 and 17643) of Perrier de la Bâthie from the vicinity of Mahatsinjo. For at least part of their careers both Benoist and Perrier de la Bâthie worked at or for P ( Dorr 1997), where the latter’s Madagascar herbarium and a previously deposited set of his collections reside. Two specimens of each collection cited in the protologue are extant at P, all of which were putatively verified by Benoist and all of which conform to elements of the protologue. From among these, the specimen of Perrier de la Bâthie 17238 with Benoist’s name in his handwriting and with a dissected flower, is designated above as the lectotype.

DISCUSSION.— The two distinguishing characters of Danguya noted by Benoist in the protologue are worth analyzing. The calyx, consisting of two large segments (each distally 2-lobed) and a minute (presumably posterior) lobe between them sometimes present ( Fig. 3E ), is unusual among Acanthaceae and possibly unique in Anisotes . Similar fusion among calyx lobes was described and illustrated by Ezcurra (1993) for the 3-segmented, 5-lobed calyx of Ruellia erythropus (Nees) Lindau ; however, in this species, the posterior lobe is not conspicuously reduced in size. Most species of Anisotes have 5-lobed calyces with the lobes homomorphic ( Baden 1981a, 1981b; Daniel et al. 2007; Vollesen 2010). However, three recently described species show greater diversity in the number and relative lengths of calyx lobes for the genus. In both A. venosus T.F. Daniel, Letsara & Martín-Bravo and A. comorensis (Lindau) T.F. Daniel , the posterior lobe is distinctly shorter than the other four lobes. In A. mayottensis T.F. Daniel calyces with both five heteromorphic lobes (the posterior lobe shorter than the other four lobes) and with only four homomorphic lobes (the posterior lobe lacking) are present. Thus, the calyx of A. pulchella is distinctive in the genus only by the fusion of the four homomorphic lobes into two apically lobed pairs. The presence of such fusion for a subset of species in genera with otherwise homomorphic lobes is evident elsewhere in the family (e.g., Ruellia ), as noted above.

The description of pollen provided above is based solely on Rakotonasolo et al. 2254 ( Fig. 4 ). Utilizing a different collection of this species ( Humbert 17981), Muller et al. (1989) described and illustrated pollen of this species as 2 (–3)-porate and 4 (–6)-pseudocolpate, which differs from the description above primarily by the lack of compound apertures (i.e., colpori). It therefore appears that apertures of pollen in Anisotes pulchella can vary from two to rarely three in number and from porate to colporate in type. Such palynological variation is not common within species of Acanthaceae . Baden (1981a, 1981b) and Daniel et al. (2013) noted the following types of pollen among species of the genus: 2-, 3-, and 4-colporate grains with 4, 6, and 8 pseudocopi, respectively and 2- and 3-aperturate grains with apertures (pores or colpori) in a trema region studded with one or two rows of insulae on each side of the aperture. It is noteworthy that Baden (1981a; 1981b) indicated that the apertures of 2- and 3-porate grains sometimes showed faint indications of colpi at the pores and that at least one taxon ( A. sessiflorus subsp. iringensis C. Baden ) showed variation in aperture number from two to three. Indeed, colpi evident on Rakotonasolo et al. 2254 are somewhat faint, or at least not as distinct as in species described and illustrated by Baden (1981b) as being colporate.

Thus, the putative morphological characters used by Benoist (1930) only partially, and not very effectively, distinguish Danguya from Anisotes in the current circumscription of the latter genus. Only in instances where pollen of A. pulchella is 2-porate, 4-pseudocolpate, and lacking insulae (e.g., usually in Humbert 17981; Muller et al. 1989, Plate 182/XXX, figs. 1–8) does it differ from that of other species in the genus. The only unique character of A. pulchella within the genus appears to be the fusion of four of the calyx lobes into two pairs. Indeed, this fusion, is likely synapomorphic for the species and readily serves to distinguish it from its congeners.

The few known specimens of A. pulchella are rather homogeneous in most characters. However, two collections (Bosser 18484 and Humbert 17981) are noteworthy by their young stems, which have much sparser and shorter trichomes with the longer (to 0.2 mm long) ones concentrated in two lines; leaves, which are narrower (up to 3.3 times longer than wide), acute at the base, acuminate at the apex, and mostly pubescent only along the major veins; and the very inconspicuous trichomes on abaxial surface of bracts, which appear almost glabrous. In other characters, they agree with the typical form of the species. They possibly represent either a seasonal (both of these collections were collected later in the year [August and November] than most of the other collections studied here) or an ecological form of the species.

Anisotes pulchella shows numerous similarities to plants from the transitional forest remnants between Sakaraha and Isalo National Park in southwestern Madagascar (e.g., Bosser 17314, Du Puy et al. MB644, and Rogers et al. 441). These yet to be identified plants, which occur at elevations between 720 and 770 m, differ by having pink bracts and white corollas with pink to red markings on the lower lip.

Preliminary molecular phylogenetic studies that included some Old World Justicieae ( McDade et al. 2000) suggested that Anisotes , as currently delimited, is not monophyletic. Indeed, Kiel et al. (2017) confirmed this; revealed that A. perplexus T.F. Daniel, Letsara & Martín-Bravo from Madagascar, which shows morphological affinities to Anisotes but has pollen like that found in Whitfieldieae and Isoglossinae, pertains to the latter subtribe; and that a potentially monophyletic Metarungia pertains to a clade sister to that containing most species of Anisotes . Comprehensive molecular and morphological studies of Anisotes are much to be desired in order to better unravel relationships among taxa of Justicieae in the Old World.

ADDITIONAL SPECIMENS EXAMINED.— MADAGASCAR. Antananarivo: Tompoketsa d’Ankazobe, P.K. 135 [ca. 17°55′S, 47°06’E], J. Bosser 18484 (MO); Ambohimalaza près d’Ankazobe [18°19′S, 047°06′E], R. Decary 7719 (K, P) . Mahajanga: KM 180 de la route Tananarive– Majunga , sur le Tampoketsa [17°45′S, 047°01″E], P. Boiteau 3012 (K, P); Massif du Vohimbohitra près de Manakana, district de Tsaratanana, au sommet du massif, [ca. 17°49′52.61″S, 047°26′08.91″E], G. Cours 1522 (P, K); entre Mandritsara et Andilamena, [ca. 16°38′48.81″S, 048°39′9.36″E], H. Humbert 17981 (K, P, US) ; près de Mahatsinjo sur le Tampoketsa entre l’Ikopa et le Betsiboka, [ca. 17°44′26.49″S, 047°04′15.34″E], H. Perrier de la Bâthie 17643 (K, P); Distr. Tsaratanana, Region Betsiboka, Ambohimanga, Commune Manakana, Vohimbohitra, 17°47′44.8″S, 047°26′06.2″E, F. Rakotonasolo et al. 2254 (CAS, K, TAN) .

Figures

FIGURE 2. Map of Madagascar showing provincial boundaries and the distribution of Anisotes pulchella.

FIGURE 1. Anisotes pulchella (Rakotonasolo et al. 2254). Remnant forest habitat on the Vohombohitra massif (top). Branch with leaves and inflorescences (middle left). Inflorescence showing bracts and flowers (bottom left). Flowers (front view). Photos by L. Rokiman.

FIGURE 3. Anisotes pulchella (Rakotonasolo et al. 2254). A. Flowering branch. B. Close-up of abaxial surface of leaf showing pubescence. C. Bract. D. Flower subtended by bract. E. Calyx. F. Pair of partially fused calyx lobes. G. Portion of stamen with anther. H. Portion of style with stigma. Drawn by Roger Lala Andriamiarisoa.

FIGURE 4. Pollen of Anisotes pulchella (Rakotonasolo et al. 2254). A. Apertural view. B. Oblique view. C. Interapertural view.