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1 July 2014 Taxonomy of Anisotes Nees (Acanthaceae: Justicieae) in the Comoros Archipelago and a preliminary List of Acanthaceae in the Islands
Thomas F. Daniel
Author Affiliations +

DANIEL, T. F. (2014). Taxonomy of Anisotes Nees (Acanthaceae: Justicieae) in the Comoros Archipelago and a preliminary list of Acanthaceae in the Islands. Candollea 69: 45–54. In English, English and French abstracts.

A new species and a new combination in Anisotes Nees are proposed for the acanthaceous flora of the Comoros Archipelago. The new species, Anisotes mayottensis T. F. Daniel, is known only from Mayotte, and can be distinguished from its Comoran congener by its unequally five-lobed (4+1) or equally four-lobed calyx; longer corolla, stamens, and thecae; and fouraperturate pollen. Anisotes comorensis (Lindau) T. F. Daniel, based on Himantochilus comorensis Lindau, is proposed for a species endemic to Grande Comore. A lectotype is designated for Himantochilus comorensis. Both species are described, mapped, and distinguished by a key; Anisotes mayottensis is also illustrated. All Acanthaceae known from the archipelago are listed in a table.


The Comoros Archipelago consists of four islands and several islets at the northern end of the Mozambique Channel in the western Indian Ocean (Fig. 1). Three of the islands, Grande Comore (Ngazidja), Anjouan (Ndzwani), and Mohéli (Mwali) currently form the independent Union of the Comoros, whereas Mayotte (Maore) is an overseas department of France. The islands are volcanic in origin with Mayotte (8–15 m.y.) the oldest and Grande Comore (ca. 2.5 mya) the youngest (Lowry & al., 1999). Floral and faunal affinities for these oceanic islands have been noted with Madagascar (e.g., Voeltzkow, 1917; Pascal & al., 2001; Rolland & al., 2005), the nearest coastline of which is about 300 km to the south and east.

Voeltzkow (1917) listed 416 species of vascular plants, including seven species of Acanthaceae, as native to the Comoros Archipelago. The incompleteness of that early listing was highlighted by the recent compilation of Barthelat & Boullet (2005) for Mayotte, which recorded more than 600 indigenous vascular plants for the one island, including 10 named Acanthaceae. Additional Acanthaceae at P, including a new species of Anisotes Nees treated here, bring the number of identified species of Acanthaceae on Mayotte to 16 (Table 1). In addition to the named species noted in Table 1, at least two others that remain unidentified also have been collected on Mayotte: a specimen of Hypoestes R. Br. (Barthelat & al. 1481, P) and a specimen of Justicia L. (Barthelat & al. 1484, P). The total vascular flora of the archipelago (native and introduced) has been estimated to be 1,500 species or more (Lowry & al., 1999; Pascal, 2002). Although the flora of the Union of the Comoros is less well known than that of Mayotte, additional Acanthaceae have been collected on those islands resulting in 23 species of the family currently being known from the Comoros Archipelago (Table 1).

Fig. 1.

— Comoros Archipelago (Union of the Comoros and Mayotte) showing distributions of Anisotes comorensis (Lindau) T. F. Daniel and A. mayottensis T. F. Daniel. The exact location of the sole collection of A. comorensis (Lindau) T. F. Daniel from Grande Comore is unknown.


Table 1.

Acanthaceae of the Comoros Archipelago. The list of taxa is based on collections at CAS, K, and P. Taxonomic status of and conservation assessment for each is currently under study. For individual islands: A = Anjouan, GC = Grande Comore, MH = Mohéli, and MY = Mayotte. When a specific island was not provided by a collector, CA (= Comoros Archipelago) is indicated.




Anisotes was revised by Baden (1981b), some renovations of African taxa were made by Vollesen (2010), and additional Malagasy species were proposed by Daniel & al. (2007, 2013). As currently circumscribed, the genus consists of 29 species that occur in Africa, the Arabian Peninsula, Socotra, and Madagascar. Two additional species are recognized here from the Comoros Archipelago. Daniel & al. (2007) noted the lack of clear morphological distinctions between Anisotes and the large and morphologically variable Justicia. In the Comoros Archipelago, Anisotes can be distinguished from Justicia by its larger corollas (20–32 vs. less than 10 mm long) with the lower lip of the limb coiled (vs. not coiled) at maturity. A treatment of Anisotes for the Comoros Archipelago is provided below in which one species is newly described from Mayotte and a species from Grande Comore previously treated in Himantochilus Benth. & Hook. f. is transferred to Anisotes.

Fig. 2.

— Pollen of Anisotes Nees in the Comoros Archipelago. A–B. Anisotes mayottensis T. F. Daniel; C–D. A. comorensis (Lindau) T. F. Daniel; A. Apertural view; B. Interapertural view; C. Apertural view; D. Interapertural view.

[A–B: Pascal 936, CAS; C–D: Humblot 1584, P]


The extent of pollen diversity among species of Anisotes is unusual for an acanthaceous genus of its size. Baden (1981a, 1981b) and Daniel & al. (2013) noted the following types of pollen among species of the genus: two-, three-, and four-colporate grains with four, six, and eight pseudocopi, respectively; two- and three-aperturate grains with apertures in a trema region studded with one or two rows of insulae; and two-pororate grains. Pollen of the two Comoran endemics (Fig. 2) does not add to this variation, but each one has a different type.

Taxonomic treatment

Anisotes Nees in A. DC., Prodr. 11: 424. 1847.

  • Typus: Anisotes trisulcus (Forssk.) Nees (≡ Dianthera trisulca Forssk.)

    For a complete list of generic synonyms, see Vollesen (2010).

    Shrubs to small trees, cystoliths present, nodes often swollen. Leaves opposite, evergreen or deciduous, (sessile to) petiolate, margin entire to crenate. Inflorescence of sessile to pedunculate dichasiate spikes or racemes or of dichasia in leaf axils; dichasia sessile to pedunculate. Bracts opposite. Bracteoles 2. Flowers sessile to pedicellate. Calyx 5-lobed, lobes equal to unequal in length, 1 lobe sometimes reduced or absent. Corolla 2-labiate, purple, red, yellow, orange, greenish, or whitish, tube shorter than limb, subcylindric (at least near base) or sometimes ± expanded distally, with 2 invaginations (from the outer surface; i.e., appearing as pubescent projections internally) on lateral surfaces, upper lip arching forward and hoodlike, entire or 2-fid, rugulate within, lower lip tightly coiled or spirally twisted like a dangling corkscrew at maturity, 3-lobed. Stamens 2, exserted from corolla tube, inserted near base or apex of corolla tube, ± appressed to upper lip and opening toward lower lip (i.e., flower nototribic), anthers 2-thecous, thecae parallel to subperpendicular, subequally to unequally inserted, lacking basal appendages or with one or both shortmucronate at base; staminodes 0. Pollen 2–4-aperturate. Capsule stipitate, head subspheric to ellipsoid, sometimes with a slight medial constriction. Seeds 4 (or fewer by abortion), subdiscoid, surfaces usually rugose, rarely pubescent (with either glandular or hygroscopic/eglandular trichomes).

    Anisotes is a Paleotropical genus of subfamily Acanthoideae, tribe Justicieae (Daniel & al., 2007; Daniel & al., 2013) with 31 species currently recognized. 23 species occur on the African mainland, six species are endemic to Madagascar, and 2 species are endemic to the Comoros Archipelago.

  • Key to Anisotes in the Comoros Archipelago

    1. Calyx lobes 5, subequal in length, lanceolate, 0.5–0.6 mm wide, margins not hyaline; bracts membranaceous, major veins evident but not conspicuous, margin ciliate with trichomes 0.1–0.3 mm long; bracteoles lanceolate, 0.3– 0.5 mm wide; corolla 20–22 mm long; stamens 10–13 mm long, thecae 1.5–1.8 mm long; pollen 2-colporate and 4-pseudocolpate; Grande Comore 1. A. comorensis T. F. Daniel

    1a. Calyx lobes 4 or 5, if 4 then equal in length, if 5 then unequal in length with 4 lobes ovate, equal in length, 1.8–2 mm wide and with 1 lobe conspicuously reduced (linear to lanceolate and 0.5–1 mm wide), margins hyaline; bracts coriaceous, major veins conspicuous, margin ciliate with trichomes to 0.8 mm long; bracteoles linear-oblanceolate 0.9–1.1 mm wide; corolla 24–32 mm long; stamens 17–18 mm long, thecae 2–2.5 mm long; pollen 4-colporate and 8-pseudocolpate; Mayotte 2. A. mayottensis T. F. Daniel

    Anisotes comorensis (Lindau) T. F. Daniel, comb. nova.

  • Himantochilus comorensis Lindau in Bot. Jahrb. Syst. 20: 61. 1894.

  • Lectotypus (designated here) : COMOROS. Grande Comore: s.l., VII.1886, Humblot 1584 (P [P00184832]!; iso-: LD [LD1212195] image seen, P [P00184831, P00184833]!).

  • Perennial to 3.5 [or more ?] dm tall. Older stems not seen; younger stems pubescent with flexuose to retrorse eglandular trichomes 0.2–0.5 mm long, trichomes ± evenly disposed or becoming concentrated in 2 lines. Leaves petiolate, petioles to 45 m long, blades membranaceous, ovate to elliptic, 60–102 mm long, 22–37 mm wide, 2.1–2.8 × longer than wide, cuneate to subattenuate at base, acuminate at apex, major veins ± prominent, secondary veins 5–7 per side, surfaces pubescent with antrorse to flexuose eglandular trichomes. Spikes axillary, mostly opposite at leaf nodes, (1-)2–4 per axil, densely bracteate, pedunculate, peduncles 3–16 mm long, pubescent like young stems, fertile portion of spike (excluding corollas) 10–22 mm long, rachis not visible, puberulent with mostly erect eglandular trichomes to 0.1 mm long. Bracts light colored, imbricate, 4-ranked (2 adjacent rows fertile; thus ± secund), membranaceous, elliptic, 6–8.5 mm long, 2.5–4 mm wide, acute- to acuminate-apiculate at apex, apiculum 0.3–1 mm long, abaxial surface sparsely pubescent with antrorse to flexuose eglandular trichomes and with an inconspicuous understory (sometimes absent) of sessile to subsessile glands to 0.05 mm long, major veins evident but not conspicuous, 5, subparallel to midvein, margin sparsely ciliate with erect to flexuose eglandular trichomes 0.1–0.3 mm long, proximal pair of bracts sterile and often smaller (4–5.5 × 2.2–3.2 mm) than fertile ones. Bracteoles lanceolate, 4–5 mm long, 0.3–0.5 mm wide, abaxial surface pubescent like bracts to nearly glabrous, only midvein evident, margin ciliate like bracts. Calyx 5-lobed, 5.5–7 mm long, tube 0.5–1 mm long, lobes lanceolate, 4.5–6 mm long, subequal in length (posterior lobe smallest), 0.5–0.7 mm wide, long-aristate at apex (aristae to 2 mm long), abaxially pubescent like bracts to nearly glabrous, margin not noticeably hyaline, ciliate. Corolla color unknown, 20–24 mm long, externally pubescent with erect to flexuose to retrorse eglandular trichomes 0.1–0.3 mm long, tube slightly and gradually expanded from near base to mouth, 8.5–11 mm long (0.43–0.55 × as long as corolla), 1.5–2.5 mm in diameter near midpoint, upper lip 10–13 mm long, entire at apex, lower lip 10–11.5 mm long, recurved to recoiled, lobes 1.5–2.2 mm long, 0.5–2 mm wide. Stamens inserted near apex of corolla tube, 10–13 mm long, not extending beyond upper lip of corolla, filaments pubescent proximally and glabrous distally, thecae parallel to subperpendicular, unequally inserted (overlapping by 0.8–1 mm), 1.5–1.8 mm long (proximal theca slightly longer than distal theca), glabrous, distal theca usually with an inconspicuous basal appendage to 0.1 mm long, proximal theca with a basal appendage 0.3–0.4 mm long. Pollen 2-colporate, 4-pseudocolpate, globose-elliptic, polar diameter (P) 36–37 μm, equatorial diameter (E) in apertural view 23 μm, equatorial diameter in interapertural view 17 μm, P:E in apertural view = 1.57, P:E in interapertural view = 2.18, longer E:shorter E = 1.35, exine bireticulate. Style ca. 18–21 mm long, not or but barely extending beyond upper lip of corolla, pubescent proximally, stigma inconspicuous, lobes (if present) not evident. Capsule and seeds not known.

  • Phenology. — Flowering in July.

  • Distribution and habitat. — Comoros Archipelago; endemic to Grande Comore island (Fig. 1); the species is known only from the type collection made in 1886 from an undisclosed locale.

  • Discussion. — There are three specimens at P, one annotated (recently) as the holotype and two as isotypes. No herbarium of deposit was cited in the protologue, and Humblot's collections were widely distributed (Lanjouw & Stafleu, 1957) including to B, where Lindau worked on Acanthaceae after 1892. If a single specimen at B was used by Lindau in creating his protologue, it would have been the holotype. Such a specimen is no longer extant at B. The specimen at P annotated as the holotype bears Lindau's name in a handwriting that resembles that of Benoist rather than that of Lindau, and would thus appear to represent either a syntype or an isosyntype. This specimen (Humblot 1584 [P00184832]), which also bears the unpublished combination attributed to Benoist, is here designated as lectotype of Himantochilus comorensis.

    Lindau (1894) indicated that H. comorensis could be distinguished from its congeners by the shape of the leaves and the much smaller flowers. Baden (1981b) treated Lindau's H. comorensis as a “doubtful taxon”, did not see the type, and noted that based on Lindau's description it was unlikely to pertain to Anisotes. Although Anisotes is not well distinguished morphologically from Justicia (Daniel & al., 2007; Daniel & al., 2013), Lindau's species contains the characteristic floral attributes of the former genus: relatively large (22–65 mm long) and strongly bilabiate corollas with ascending cochlear aestivation, a relatively short corolla tube (tube: corolla length up to 0.56, but usually 0.33 or less), a hoodlike and internally rugulate upper lip, and a lower lip that is usually recoiled.

    Pollen of this species (Fig. 2) is two-colporate with two pseudocolpi in each mesocolpium. Similar pollen was noted in Anisotes subcoriaceus T. F. Daniel, Letsara & Martín-Bravo from Madagascar (Daniel & al., 2013).

  • Anisotes mayottensis T. F. Daniel, spec. nova (Fig. 3, 4).

  • Typus: MAYOTTE: Bénara, 600 m, 26.V.1997, fl., Pascal 936 (holo-: CAS!; iso-: K, P!).

  • Species calycis lobis majoribus ovatis et 3–5 mm longis × 1.5–2 mm latis, corolla purpureo-rubra et 24–32 mm longa, et polline 4-aperturato a congeneribus diversa.

    Shrubs to 1 m tall. Older stems dark greenish, brown, or slightly pinkish; younger stems evenly and ± densely pubescent with retrorsely to antrorsely appressed eglandular trichomes to 0.5 mm long. Leaves petiolate, petioles to 52 mm long, blades membranaceous, ovate, 56–116 mm long, 23–44 mm wide, 2.1–3.4 × longer than wide, rounded to subcuneate at base, acuminate at apex, venation ± prominent, secondary veins 4–7 per side, surfaces pubescent (trichomes mostly restricted to midvein) with appressed eglandular trichomes. Spikes axillary, alternate or opposite at leaf nodes, 1–2 per axil, densely bracteate, pedunculate, peduncles 4–15 mm long, pubescent with antrorsely appressed eglandular trichomes, fertile portion of spike (excluding corollas) 10–24 mm long, rachis not visible, nearly glabrous or sparsely pubescent with erect to flexuose eglandular trichomes to 0.2 mm long. Bracts green and lighter (hyaline) toward margin and apex, imbricate, 4–ranked (2 adjacent ranks fertile; thus ± secund), coriaceous, (ovate-elliptic to) elliptic (to obovate-elliptic), 5.5–7.5 mm long, 2.7–3.5 mm wide, acute-apiculate at apex, apiculum to 0.5 mm long, abaxial surface puberulent with erect to antrorse eglandular trichomes to 0.05 (-0.1) mm long, major veins conspicuous, 5, parallel to midvein, margin ciliate with erect to flexuose eglandular trichomes to 0.8 mm long, proximal pair of bracts sterile. Bracteoles linear-oblanceolate, 4–5.7 mm long, 0.8–1.2 mm wide, abaxial surface pubescent like bracts (to nearly glabrous), 1–3-veined, margin ciliate like bracts. Calyx either 5-lobed with 1 lobe conspicuously reduced or equally 4-lobed, 6–9 mm long, tube 3–4 mm long, 4 lobes ovate, 3–5 mm long, equal in length, 1.5–2 mm wide, subacuminate at apex, abaxially puberulent with eglandular and subglandular trichomes < 0.05 mm long, margin hyaline and ciliate, 5th lobe (if present) linear to lanceolate, 2–3 mm long, 0.5–1 mm wide, otherwise like larger lobes. Corolla purplish red, 24–32 mm long, externally pubescent with subglandular and eglandular trichomes < 0.05–0.2 mm long, tube subcylindric proximally, expanded distally, 6–13 mm long (0.25–0.46 × as long as corolla), 2.5–3 mm in diameter near midpoint, upper lip 14–24 mm long, entire at apex, lower lip recoiled, 15–24 mm long, lobes 3 mm long, 0.9–1 mm wide. Stamens inserted near apex of corolla tube, 17–18 mm long, not extending beyond upper lip of corolla, filaments glabrous distally, thecae subparallel, unequally inserted (overlapping by 1–1.5 mm), 2–2.5 mm long (± equal in length), glabrous, distal theca with a basal appendage 0.1–0.2 mm long, proximal theca with a basal appendage 0.3–0.6 mm long. Pollen 4-colporate, 8-pseudocolpate (the 2 pseudocolpi in each mesocolpium often fused near poles to form pseudocolpal ellipses), euprolate to perprolate, polar diameter (P) 41–60 μm, equatorial diameter (E) 21–27 μm, P:E = 1.56–2.86, exine bireticulate. Style 24–32 mm long, not extending or extending beyond upper lip of corolla, glabrous distally, stigma inconspicuous, lobes (if present) not evident. Capsule and seeds not known.

  • Phenology. — Flowering: May–June.

  • Distribution and habitat. — Comoros Archipelago; known from two relatively recent collections from the crests of the southern highlands on the island of Mayotte (Fig. 1), where it is endemic; plants occur in humid evergreen forest (with Olea capensis L., Labramia mayottensis Labat , M. Pignal & O. Pascal, Dicoryphe platyphylla Tul., Strychnos mitis S. Moore, Syzygium sp., Gastonia duplicata Baill., Grisollea myriantha Baill., Nuxia pseudodentata Gilg, Ravensara areolata Kosterm., Scolopia coriacea Tul., Trophis montana (Leandri) C. C. Berg) at elevations between 350 and 600 m.

  • Local name. — “Nanatsy be” (Shibushi ; Barthelat & al. 386).

  • Discussion. — This species shows variation in the number of calyx lobes from five (4+1) to four. The presence of both forms on Barthelat & al. 386 suggests that the reduced fifth lobe is sometimes lost. Similar variation in the number and configuration of calyx lobes is known for Justicia, but apparently has not been reported in other species of Anisotes. It is noteworthy that A. comorensis and at least one Malagasy species (A. venosus T. F. Daniel, Letsara & Martín-Bravo; Daniel & al., 2013) have a calyx with one lobe somewhat reduced in size relative to the others.

    The four-aperturate pollen of this species (Fig. 2) is unusual in the genus. It has been previously documented only for the tropical west African species, A. guineensis Lindau (Baden, 1981b).

  • Paratypi. — MAYOTTE: Grande Terre, Tsararano, Bénara, Crètes du Bénara, 10.V.2001, Barthelat & al. 386 (MO, P); Grande Terre, Tsararano, Réserve Forestière du Bénara, ch. de crête-sommet, 27.V.2001, Barthelat & al. 1188 (P); Mlima Choungi, 10.VI.1996, Pascal 563 (P).

  • Fig. 3.

    Anisotes mayottensis T. F. Daniel. A. Habit; B. Leaf; C. Bract; D. Bracteole; E. Calyx; F. Distal portion of stamen with anther.

    [A, C–E: Barthelat & al. 386, MO; B, F: Pascal 936, CAS] [Drawing: Noel Pugh]


    Fig. 4.

    Anisotes mayottensis T. F. Daniel. Distal portion of stem with inflorescences.

    [Photo: F. Barthelat (used with permission)]



    For their assistance with various aspects of this study, I thank F. Barthelat, E. Bidault, P. Phillipson, N. Pugh, S. Serata, and the late J.-N. Labat. I am grateful to the following herbaria for loans and other courtesies: CAS, G, MO, and P.



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    Thomas F. Daniel "Taxonomy of Anisotes Nees (Acanthaceae: Justicieae) in the Comoros Archipelago and a preliminary List of Acanthaceae in the Islands," Candollea 69(1), 45-54, (1 July 2014).
    Received: 12 November 2013; Accepted: 23 January 2014; Published: 1 July 2014
    Comoros Archipelago
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