Comparative anatomy of young stems and leaves of 16 Dalbergia species (Fabaceae) from Madagascar and their taxonomic significance Author Ramanantsialonina, Ravo Nantenaina 0000-0001-6700-7774 Département de Biologie et Écologie Végétales, Université d’Antananarivo, B. P. 906, Antananarivo 101, Madagascar r.ramanantsialonina@gmail.com Author Sandratriniaina, Ninah Andrianasolo 0000-0001-9525-4879 Département de Biologie et Écologie Végétales, Université d’Antananarivo, B. P. 906, Antananarivo 101, Madagascar asandratriniaina@gmail.com Author Rakouth, Bakolimalala 0000-0001-5710-2006 Département de Biologie et Écologie Végétales, Université d’Antananarivo, B. P. 906, Antananarivo 101, Madagascar ba.rakouth@gmail.com Author Wiemann, Michael C. 0009-0001-6754-2029 Forest Products Laboratory, University of Wisconsin Madison michael.wiemann@usda.gov Author Ravaomanalina, Bako Harisoa 0009-0007-9547-4725 Département de Biologie et Écologie Végétales, Université d’Antananarivo, B. P. 906, Antananarivo 101, Madagascar & Département de Biologie et Écologie Végétales, Université d’Antananarivo, B. P. 906, Antananarivo 101, Madagascar harisoa.ravaomanalina@univ-antananarivo.mg text Phytotaxa 2024 2024-05-31 652 1 33 46 http://dx.doi.org/10.11646/phytotaxa.652.1.3 journal article 301761 10.11646/phytotaxa.652.1.3 e11288a7-badb-4862-98ee-af084cee4c02 1179-3163 13216545 Identification key for the 16 studied Malagasy Dalbergia The following identification key for the 16 Malagasy Dalbergia species is based on qualitative features that are easy to observe: the shape of the lamina, the pattern of vascularization in the petiole, presence or absence of papillae, hypodermis and its type , arrangement and disposition of bundle sheath. 1a Shape of lamina: Flat-flat .................................................................................................................................................. D. lemurica 1b Shape of lamina: other........................................................................................................................................................................2 2a Presence of papillae in lower epidermis.............................................................................................................................. D. baronii 2b Lower epidermis lacking papillae ......................................................................................................................................................3 3a Hypodermis present at mesophyll .................................................................................................................................... D. greveana 3b Hypodermis absent at mesophyll........................................................................................................................................................4 4a Palisade parenchyma in all mesophyll .................................................................................................................... D. razakamalalae 4b Palisade parenchyma only on the adaxial side of mesophyll .............................................................................................................5 5a Bundle sheath Type I (parenchyma thin-walled irregularly shaped)..................................................................................................6 5b Bundle sheath Type II (parenchyma thick-walled and rounded)......................................................................................................14 6a Bundle sheath Type I on the left and right-sides of the vascular bundles ................................................................. D. purpurascens 6b Bundle sheath Type I surrounding the vascular bundle......................................................................................................................7 7a Bundle sheath Type I partially surrounding the vascular bundle .......................................................................................................8 7b Bundle sheath Type I completely surrounding the vascular bundle ................................................................................................ 12 8a Open arc vascular bundles with one adaxial vascular bundle at proximal part of petiole .................................................. D. urschiii 8b Open arc vascular bundles at proximal part of petiole .......................................................................................................................9 9a Simple open arc vascular bundles at proximal part of petiole........................................................................................... D. oronjiae 9b Open arc vascular bundles with slightly incurved ends at proximal part of petiole.........................................................................10 10a Open arc vascular bundle at distal part of petiole ................................................................................................................ D. davidii 10b Vascular bundle clearly separated at distal part of petiole ...............................................................................................................11 11a Vascular bundle clearly separated into 5 at distal part of petiole ................................................................................... D. abrahamii 11b Vascular bundle clearly separated into 6 to 9 at distal part of petiole ......................................................................... D. chlorocarpa 12a Closed arc vascular cylinder at distal part of petiole....................................................................................................... D. monticola 12b Open arc vascular bundles at distal part of petiole...........................................................................................................................13 13a Simple open arc vascular bundle at proximal part of petiole ................................................................................... D. pseudobaronii 13b Open arc clearly separated into five vascular bundles at proximal part of petiole ............................................................... D. bathiei 14a Bundle sheath Type II completely surrounding the vascular bundles............................................................................. D. orientalis 14b Bundle sheath Type II on abaxial side..............................................................................................................................................15 15a Open arc with one adaxial vascular bundles at distal part of petiole ............................................................................. D. normandii 15b Vascular bundle clearly separated into 6 to 9 at distal part of petiole .................................................................................. D. obtusa