Hilsenbergia croatii J.S. Mill., 2003

Miller, James S., 2003, Classification of Boraginaceae subfam. Ehretioideae: Resurrection of the genus Hilsenbergia Tausch ex Meisn., Adansonia (3) 25 (2), pp. 151-189 : 168-171

6. Hilsenbergia croatii J.S. Mill. , sp. nov.

Frutex vel arbor parva , ramunculis glabris. Folia decidua, alterna vel dense ad apices ramunculorum brachyblastorumve in fasciculos densos disposita; lamina late-obovata, late-elliptica, vel late-ovata usque latedepresse-ovata, 9-21 mm longa, 8-20 mm lata, apice rotundata usque emarginata, basi rotundata usque obtusa , margine integra, utrinque glabra ; petiolo 4-12 (-15) mm longo. Inflorescentiae terminale, cymosae vel ex fasciculis 1- ad 3-floris constans. Flores bisexuales; calyce campanulato, 3-4 mm longo, 5 lobo, extus glabro vel margine ciliato; corolla alba , urceolata usque campanulata , 5-6 mm longa. Fructus drupaceus, aurantiacus , ovoideus usque late-ovoideus, 4-5 mm longus, 3.5-5 mm in diam.; pyrenis 4, alatis.

TYPUS. — Miller & Keating 4514, Prov. Toliara, Tsivonoakely, 20-30 km N of Tuléar on the road to Morombe , 5-10 m, 23°12’S, 43°37’E, fl., 11 Nov. 1989 (holo-, MO!; iso-, P!, TAN!).

Shrub or small tree, rarely to 7 m tall, the twigs glabrous, increasingly fissured and encrusted with waxy coating with age. Leaves deciduous, alternate, but borne densely at the end of shoots or on short lateral spur shoots; blades widely obovate, widely elliptic, or widely ovate to widely depressed obovate, widely depressed elliptic, or widely depressed ovate, 9-21 mm long; 8-20 mm wide, (length:width ratio 3:2 - 2:3), the apex rounded to emarginate, the base rounded to obtuse and sometimes somewhat decurrent along the petiole, the margin entire, both surfaces glabrous, the venation brochidodromous, the midrib slightly raised or even with the leaf surface above, raised below, the secondary veins 3(-5), the tertiary venation reticulate; petioles 4-12(-15) mm long, usually nearly as long as the leaf blade, glabrous or puberulent on the adaxial surface near the base, flattened or canaliculate on the adaxial surface.

Inflorescences terminal, 1-3-flowered fascicles or up to 8-flowered cymes, the branches glabrous. Flowers bisexual, on pedicel-like inflorescence branches 1-5(-10) mm long; calyx campanulate, 3-4 mm long, 3-5 mm wide, 5-lobed, the lobes valvate, ovate to triangular, sometimes uneven, 0.7-1.5 mm long, glabrous or minutely ciliate on the margins; corolla white, urceolate to campanulate, 5-6 mm long, 4.5-5.5 mm wide, 5-lobed, the lobes ovate, erect to reflexed, 1.5-2.5 mm long; stamens 5, the filaments 2.5-3 mm long, the upper 1-2 mm free, glabrous, the anthers lanceoloid, 1-2 mm long; ovary conical, 1- 1.5 mm long, 0.8-1 mm wide, the style 1.5- 2 mm long, the 2 stigmas capitate, angled to nearly lateral on the style apex.

Fruits drupaceous, orange at maturity, borne in the persistent, cup-shaped to spreading calyx, ovoid to broadly ovoid, 4-5 mm long, 3.5-5 mm in diameter, the endocarp bony, separating into 4 single-seeded pyrenes at maturity, 3.5 mm long, 2.5 mm wide, these ribbed on the exterior surface. — Fig. 8 .

Hilsenbergia croatii is similar in appearance and probably closely related to H. leslieae and the two are easily confused. The two species are quite distinct in the field, but they regularly occur sympatrically and herbarium specimens are often difficult to separate. In the field, H. croatii , is a more laxely branched shrub whereas H. leslieae is so densely three-dimensionally branched, that it is difficult to press into herbarium specimens. The two are best distinguished from herbarium material on the basis of their leaves. H. croatii has leaf blades that are about as long as wide, with a rounded to obtuse base, and a petiole about the same length as the blade. In contrast, H. leslieae has leaf blades that are distinctly longer than wide (length:width ratio 3:1 - 3:2), with a cuneate base, and a petiole less than half of the length of the blade. Although both species produce few flowers per inflorescence, H. croatii occasionally produces multiply-branched cymose inflorescences with as many as 8 flowers, while inforescences with more than 4 flowers are not known from H. leslieae .

Hilsenbergia croatii is named in honor of Thomas B. CROAT, one of the most prolific plant collectors in history, who made many interesting plant collections in Madagascar in 1975, including several gatherings of this species.

DISTRIBUTION. — Hilsenbergia croatii is known only from dry regions of southern

Madagascar ( Fig. 6 ) on both sandy and calcareous substrates.

CONSERVATION STATUS. — Provisional IUCN Red List Category: Endangered (EN B2ab(i-iv)). Hilsenbergia croatii is known from only two areas in southern Madagascar where its Extent of Occurrence is limited to 90 km 2. The forests in the vicinity of Tuléar are being both cleared and selectively logged to produce charcoal and are under great threat.

PARATYPES. — MADAGASCAR: Bernardi 11385, Prov. Toliara, 23-25 km N of Tuléar on the road to Manombo across the Fiherenana, 23°S, 43 o 40’E, fr., 11 Nov. 1967 ( K!, P!) ; Chauvet 82, Prov. Toliara, environs de Tuléar , route de Sarodrano, 23°31’S, 43°44’E, 11 Mar. 1961 ( P!) ; Croat 30822, Prov. Toliara, along highway near beach 12 km N of Tuléar, more than 10 m above sea level, 23°10’S, 43°40’E, fl., 5 Feb. 1975 ( MO!, P!) ; Croat 30903, Prov. Toliara, along road to Morombe 16-18 km N of Tuléar, near sea level, 23°13’S, 43°40’E, fr., 6 Feb. 1975 ( MO!, P!) ; Decary 18715, Prov. Toliara, Manombo , tables, 22°58’S, 43°58’E, fl., 22 Feb. 1943 ( MO!, P!) ; Humbert & Perrier 2555, Prov. Toliara, environs de Tuléar , delta du Fiherenana, 2-10 m, 23°18’S, 43°36’E, fl., 14-26 Sep. 1924 ( MO!, P!) ; Leandri 3860, Prov. Toliara, environs de Tuléar , route de Manombo, 0-200 m, 23°13’S, 43°40’E, 15 Nov. 1960 ( P!) ; Peltier 3388, Prov. Toliara, Tsivonoa , 23°08’S, 43°37’E, fr., 11 Sep. 1961 ( P!) ; Perrier de la Bâthie 19018, Prov. Toliara, dunes de Tuléar , 23°20’S, 43°40’E, fr., s.d. ( P!) ; Phillipson 3450, Prov. Toliara, 38 km SW of Ampanihy, on road to Androka, 200 m, 24°50’S, 44°25’E, fr., 5 Feb. 1990 ( MO!, P!) ; Rabesandratana 4036, Prov. Toliara, Ifaty , 23°09’S, 43 o 36’E, 13 Dec. 1993 ( P!) ; Service Forestier : SF9911 , Prov. Toliara, Ft. Dauphin, dunes de Mandrare, village le plus proche Tanandava, Canton Amoasary, poste Behara, 24°39’S, 46°26’E, fr., 9 May 1954 ( P!, TEF!) ; Service Forestier: SF27934 (Capuron), Prov. Toliara, sur la route de Manombo, au nord du Fiherenana, 23°13’S, 43°40’E, fr., 8-12 Nov. 1967 ( P!, TEF!) ; Service Forestier: SF 28970 (Capuron), Prov. Toliara, sables littoraux, au nord de Tuléar , sur la route de Manombo, P. K. 12-13, 23°13’S, 43°40’E, 6 Dec. 1969 ( P!) .

Figures

Fig. 8. — Hilsenbergia croatii J.S. Mill.: A, flowering branch; B, flower; C, open corolla showing androecium and gynoecium; D, open flower with corolla and androecium removed to show gynoecium; E, top view of fruit with persistent calyx; F, basal view of fruit with persistent calyx; G, dorsal view of pyrene. Leandri 3860. Drawn by A. JOUY.

Fig. 6. — Distributions of Hilsenbergia species, mapped on the simplified bioclimate zones of Madagascar (after CORNET 1974; see SCHATZ 2000).