A Second Species of the Malagasy Genus Secamonopsis (Asclepiadaceae) Laure CiveyrelLaboratoire de Palynologie & Paleoenvironnements, ISEM-EPHE, Universit6 Montpellier II 34095, Montpellier cedex 05, France Jens Klackenberg Naturhistoriska riksmuseet, Sektionen for fanerogambotanik, S-104 05 Stockholm, SwedenABSTRACT. Secamonopsis microphylla sp. nov.,from dry southern Madagascar, is described, illus-trated, and compared to S. madagascariensis Ju-melle, the only other known species of this genus. While preparing a treatment of the tribe Seca-moneae (Asclepiadaceae) for the Flore de Mada-gascar et des Comores, and during the course of asurvey of the pollen structure within this tribe, anew species, Secamonopsis microphylla, was en-countered. This adds a second species to the hith-erto monotypic Malagasy genus Secamonopsis Ju-melle.Secamonopsis microphylla Civeyrel & Klack-enberg, sp. nov. TYPE: Madagascar. Toliara Prov.: 17 km E of Toliara on Road No. 7, E of "Montagne de la Table," alt. 110 m, 20 Nov. 1994, Civeyrel 1242 (holotype, P; isotypes, K, S, TAN). Figure 1. Species haec a Secamonopsi madagascariensi habitufruticoso, brachyblastis foliiferis, inflorescentiis 1-3 flori-bus et foliis minoribus differt. Shrub, prostrate or erect, up to 1.5 m tall, withyoung branches � densely covered by short ap-pressed hairs, glabrescent. Leaves mostly on op-posite brachyblasts, grayish green with reddishmargin; blade 5-10 x 2-3 mm, oblong to narrowlyobovate, tapering at base into a distinct petiole,usually rounded but sometimes acute or truncate atthe apex, with sparse to rather dense short ap-pressed hairs on both sides, sparser above, witheven margin; venation with only midrib visible; epi-dermal cells of lower leaf surface tuberculate-pa-pillate; petiole 1-2 mm long, with appressed hairs.Flowers pentamerous, actinomorphic, usually soli-tary but sometimes 2-3 on the brachyblasts; pedi-cels 1-2 mm long; bracts 2 or 3, 1-3 mm long.Calyx lobes free, 1.8-2.4 X 1.5-2.0 mm, concave,longer than the corolla tube, obovate to � circular,rounded at the apex, hairy outside and along themargin, glabrous inside, without colleters. Corollaimbricate, with lobes fused for ca. V/ of their lengthinto a tube, yellow; tube 0.9-1.2 mm long, withlong white retrorse hairs in upside down Vs with 5bunches of erecto-patent hairs at the top below thelobe sinuses; lobes 1.5-1.7 X 1.2-1.4 mm, oblong,rounded at the apex, thick, glabrous. Stamens in-serted at base of corolla tube; staminal column 0.6-0.8 mm long; filaments with horny margins distinct-ly projecting at base; thecae papillately hairy at thetop. Coronal lobes inserted along lower half of an-thers, 0.3-0.5 mm long, dorsiventrally compressed,� as broad as long, rounded at the apex, straight,much shorter than the staminal column, glabrous.Pollinia seemingly 2 per corpusculum but in fact 4glued together in pairs, ca. 0.1 mm long, � as-cending, lens-shaped to ellipsoid, attached to 2narrow distinct caudicles on an ellipsoid soft cor-pusculum. Stigma head slightly projecting abovethe staminal column; narrower upper part ca. 0.4mm long, slightly bifid at the apex. Follicles usuallypaired, ca. 4 x 0.5 cm, narrowly ovoid, glabrous,horizontal. Seeds ca. 5 mm long; hairs 7-15 mmlong. Secamonopsis microphylla is sympatric with thehitherto only known species of Secamonopsis, S.madagascariensis Jumelle (1908: 6), but seems tobe restricted to calcareous soil with rather sparseshrub vegetation while S. madagascariensis is usu-ally found in gneissic areas. It is distributed in thedry southwestern part of Madagascar and has notbeen found outside the Southern Domain phytoge-ographical area (after Humbert, 1955). FloweringNovember to March. Secamonopsis microphylla clearly belongs to thegenus Secamonopsis, although it differs consider-ably in habit from S. madagascariensis. It has thesame structure of the gynostegium and the char-acteristic pollinaria as in S. madagascariensis. TheNovoN 6: 144-146. 1996.
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