Schrenkielleae Al-Shehbaz, Hendriks, M.Koch, F.Lens, Lysak, C.D.Bailey, Mumm. & D.A.German, trib. nov. (1: 1)

German, Dmitry A., Hendriks, Kasper P., Koch, Marcus A., Lens, Frederic, Lysak, Martin A., Bailey, C. Donovan, Mummenhoff, Klaus & Al-Shehbaz, Ihsan A., 2023, An updated classification of the Brassicaceae (Cruciferae), PhytoKeys 220, pp. 127-144 : 127

Schrenkielleae Al-Shehbaz, Hendriks, M.Koch, F.Lens, Lysak, C.D.Bailey, Mumm. & D.A.German, trib. nov. (1: 1)

Type.

Schrenkiella D.A.German & Al-Shehbaz

Description.

Herbs annual, glaucous. Trichomes absent. Multicellular glands absent. Cauline leaves petiolate to subsessile, fleshy, cuneate at base, not auriculate. Racemes ebracteate, elongated in fruit, rachis strongly flexuous. Flowers actinomorphic; sepals suberect, base of lateral pair not saccate; petals absent, rarely present, white, subequaling sepals; claw obsolete; filaments slender, unappendaged; pollen 3-colpate; ovules 24-50 per ovary. Fruits dehiscent siliques, linear, latiseptate, unsegmented; septum complete; styles distinct; stigma entire. Seeds biseriate; cotyledons incumbent. x = 7.

Distribution.

Schrenkiella parvula (Schrenk) D.A.German & Al-Shehbaz is sporadically distributed in Armenia, Azerbaijan, Iran, Kazakhstan, Russia, Turkey, Turkmenistan, and Uzbekistan.

4. Further tribal comments

The following alphabetical tribal discussions are based on the phylogenies of Hendriks et al. (2022), along with comparison of the recent family-wide phylogenies of Nikolov et al. (2019), Walden et al. (2020), and few earlier ones. Generic limits and species number closely follow BrassiBase ( Kiefer et al. 2014) with some updating. As above, tribal names are followed in parenthesis by numbers of genera and species, and those that showed no conflict with previous phylogenies are not discussed here. They include Anastaticeae (13: 67), Aphragmeae (1: 13), Biscutelleae (5: 74), Boechereae (9: 125), Buniadeae (1: 2), Calepineae (3: 9), Cardamineae (14: 344), Chorisporeae (4: 56), Cochlearieae (2: 29), Coluteocarpeae (1-12: 130), Crucihimalayeae (3: 15), Erysimeae (1: 274), Euclidieae (30: 155), Eutremeae (1: 44), Halimolobeae (5: 39), Heliophileae (1: 105), Hesperideae (1: 52), Isatideae (5: 99), Kernereae (3: 3), Lepidieae (1: 268), Malcolmieae (1: 6), Megacarpaeeae (2: 11), Microlepidieae (15: 57), Notothlaspideae (1: 3), Oreophytoneae (2: 7), Physarieae (7: 133), Schizopetaleae (4: 21), Shehbazieae (1: 1), Sisymbrieae (1: 49), Smelowskieae (1: 25), Stevenieae (2: 10), Thelypodieae (34: 235), Thlaspideae (13: 39), Turritideae (1: 2), and Yinshanieae (1: 4).

Aethionemeae (1: 58). The tribe is distributed primarily in SW Asia and the Mediterranean region, with the center of greatest diversity located in Turkey, in which 23 of the 40 species are endemic. All previous molecular studies have supported the tribal position as a sister clade to the rest of the Brassicaceae recognized above at subfamilial level.

Alysseae (24: 282). The tribe is almost exclusively distributed in Eurasia, with several native species in North Africa and one in North America. The largest and most complex genera are Alyssum L. and Odontarrhena C.A. Mey. ex Ledeb. with about 114 and 91 species, respectively. The tribe has recently been revised by Španiel et al. (2015), and its database AlyBase (www.alysseae.sav.sk; Španiel et al. 2015) should be consulted for further data and updates. All except Brachypus Ledeb. (1 sp.), Galitzkya V.V. Botschantz. (3 spp.), and Takhtajaniella V.E. Avet. (1 sp.) are included in the phylogeny by Hendriks et al. (2022).

Alyssopsideae (4: 9). A small Asian tribe distributed predominantly in Afghanistan, Azerbaijan, Iran, Tajikistan, and Turkmenistan. It is monophyletic in Hendriks et al. (2022) and a sister clade to Chrysochamela and together are sister to Pseudoarabidopsis . These two genera belong to paraphyletic Camelineae III and together are sister to the Turritideae (2 spp.). The sister relationship of Pesudoarabidopsis to the Turritideae was demonstrated earlier by Walden et al. (2020) who showed that their clade is distinct from the Camelineae including the generic type Camelina . It is clear that these taxa do not belong to the Camelineae s. str. ( Hendriks et al. 2022), but further studies are needed to explore whether they are well supported within Alyssopsideae .

Anchonieae (9: 75). Except for several species of Matthiola W.T. Aiton in Europe, the tribe is distributed primarily in SW and C Asia, and Africa. Only monospecific Eremoblastus Botsch. is not covered in Hendriks et al. (2022). The generic type, Anchonium DC., has recently been reduced to synonymy of the earlier-published Sterigmostemum M. Bieb. ( German and Al-Shehbaz 2017). The tribe is characterized by the presence of multicellular-multiseriate glands, though apparently these structures were independently lost in Veselskya Opiz (1 sp.), one species of Sterigmostemum , and some species of Matthiola (ca. 56 spp.). Such glands are also found in the related tribes Chorisporeae and Dontostemoneae .

Arabideae (18: 559). The tribe is the largest and most complex in the family. It includes ten monospecific genera, and Draba L. (ca. 410 spp.), Arabis L. (ca. 100 spp.), and Aubrieta Adans. (23 spp.) are the most species rich ones. The tribe has been the focal topic for the Koch lab (Heidelberg University) for about three decades and despite carving nearly a dozen segregates into several tribes, Arabis still needs further focus and taxonomic adjustments are under consideration (see Koch et al. 2022 for references).

Asteae (2: 2). The findings of Hendriks et al. (2022) strongly justify merging the Mexican monospecific tribe Scoliaxoneae with the earlier published Asteae . That clade is most closely related to the South American CES clade sensu Salariato et al. (2016). These findings are in full agreement with those of Walden et al. (2020), but not closely related to the European Kernereae , a tribe more closely related to the Cochlearieae , Conringieae , and Coluteocarpeae in Hendriks et al. (2022).

Brassiceae (53: 243). The tribe has been recognized by all authors since it was established by de Candolle (1821). With the exception of a few genera (e.g., Ammosperma Hook.f., Bivonaea DC., Horwoodia Turrill, and Pseuderucaria O.E. Schulz), the plants have conduplicate cotyledons and/or segmented (heteroarthrocarpous) fruits. All except four genera ( Cordylocarpus Desf., Fezia Pit. ex Batt., Muricaria Desv., and Rytidocarpus Coss.) were included in Hendriks et al. (2022). Unlike the findings of Walden et al. (2020) based on chloroplast data, Bivonaea was placed as sister to the tribe Fourraeeae .

Monophyly of Brassica is established based on most recent molecular phylogenies (e.g., Hendriks et al. 2022). About a dozen species of Brassica have been transferred to Guenthera Andrz., but monophyly of the latter with additional species needs to be established. Two other genera of the tribe, Diplotaxis DC. and Erucastrum C. Presl, remain artificially delimited, and similar studies are needed to accurately define their boundaries.

Camelineae (4: 16). As shown by Hendriks et al. (2022), the Camelineae as hitherto accepted are paraphyletic, of which Camelineae I includes Camelina (8 spp.), Capsella Medik. (5 spp.), Catolobus (1 sp.), and Neslia Desv. (2 spp.). Camelineae III is discussed above in connection with the Alyssopsideae . Finally, Camelineae II includes only Arabidopsis , which is shown in Hendriks et al. (2022) and some earlier studies to form a distinct clade from the rest of the Camelineae and recognized above in its own tribe. With the exclusion of Camelineae II and III, the tribal description of Camelineae s.str. is updated below:

Herbs, annual or perennial. Trichomes stalked or sessile, stellate, dendritic, or forked, sometimes mixed with simple ones. Multicellular glands absent. Cauline leaves sessile, mostly entire, auriculate or sagittate at base. Racemes ebracteate, often elongated in fruit. Flowers actinomorphic; sepals erect to spreading, lateral pair often not saccate at base; petals white, yellow, orange, pink, or purple, often with a distinct claw; filaments unappendaged, wingless; pollen 3-colpate; ovules 2-40 per ovary. Fruits silicles or siliques, dehiscent or indehiscent, latiseptate, terete, or angustiseptate, unsegmented; styles often distinct; stigma entire or rarely 2-lobed. Seeds biseriate, uniseriate, or aseriate; cotyledons incumbent or rarely accumbent.

Conringieae (1: 3) vs. Plagiolobeae (1: 5). The Conringieae sensu Al-Shehbaz (2012) was broadly delimited to encompass a heterogenous assembly of the genera Conringia (6 spp.) and Zuvanda (3 spp.). The findings of Hendriks et al. (2022) agree with those of Walden et al. (2020) and Nikolov et al. (2019) in that the Conringieae s.l. is not monophyletic. Based on the molecular findings and re-evaluation of morphology in light of those studies, one species, C. planisiliqua , was assigned to the genus Iljinskaea ( Al-Shehbaz et al. 2021) of the Isatideae , Zuvanda and three species of Conringia are currently recognized as five species of Plagioloba of the tribe Plagiolobeae ( German 2021; German 2022; Khosravi et al. 2022), and the remaining three species of Corningia are retained in the genus. The Conringieae differs from the Plagiolobeae by having 4- to 8-angled (vs. terete) fruits and entire (vs. slightly to prominently 2-lobed) stigmas with connivent (or sometimes decurrent) lobes.

Cremolobeae (4: 32). As currently recognized ( Salariato et al. 2016; Salariato et al. 2020), the tribe includes the genera Aimara Salariato & Al-Shehbaz (1 sp.), Cremolobus (5 spp.), Menonvillea (24 spp.), and Yunkia Salariato & Al-Shehbaz (2 spp.). Hendriks et al. (2022) included five species of the tribe that belong to the first three genera, and their findings support the monophyly of the tribe, as did the above studies of Salariato et al. (2016, 2020). However, Walden et al. (2020) showed that Menonvillea did not fall with the rest of the tribe, and further studies are definitely needed (see tribe Eudemeae below).

Descurainieae (6: 48). Except for the monospecific Patagonian Trichotolinum O.E. Schulz, which has not yet been included in any phylogenetic studies, the position of other five genera in Hendriks et al. (2022) agrees with earlier studies.

Dontostemoneae (2: 14). Position of Dontostemoneae , Chorisporeae , and their intertribal hybrid Shehbazieae are in full agreement with the initial findings by German and Friesen (2014) and Walden et al. (2020). In contrast to these consistent findings, Liu et al. (2021) probably erroneously considered Shehbazia D.A. German as member of the paraphyletic Chorisporeae .

Eudemeae (9: 40). Hendriks et al’s. (2022) sampling of five species of five genera supports the monophyly of this tribe. Together with the other exclusively South American tribes, Cremolobeae (see above) and Schizopetaleae of the CES clade sensu Salariato et al. (2016) and North American Asteae , the group forms a monophyletic New World clade. Such generic relationship was first observed by Walden et al. (2020) who demonstrated that Menonvillea falls outside the Cremolobeae . Salariato et al. (2022) showed that Alshehbazia Salariato & Zuloaga (3 spp.), Aschersoniodoxa Gilg & Muschl. (3 spp.), Gongylis Theophr. ex Molinari & Sánchez Och. (1 sp.), Onuris Phil. (5 spp.), and Xerodraba Skottsb. (5 spp.) are monophyletic, whereas Brayopsis (9 spp.), Dactylocardamum Al-Shehbaz (2 spp.), Eudema Humb. & Bonpl. (4 spp.), and Stenodraba O.E. Schulz (8 spp.) are polyphyletic. Clearly, the entire complex is much in need of further studies based on extensive sampling of most species of the entire complex.

Fourraeeae (2: 3) This tribe has recently been established by Koch et al. (2022) to accommodate three species previously assigned to Arabis . Those authors discussed previously published extensive molecular studies that did not support the placement of those species within Arabis . The group includes the European Fourraea alpina (L.) Greuter & Burdet and two Moroccan species assigned to the new genus Hurkaea Al-Shehbaz, M.A. Koch, R. Karl & D.A. German. The data of Hendriks et al. (2022) strongly support the recognition of this tribe.

Hillielleae (1: 11). The recently established Hillielleae was previously part of the Yinshanieae , but Chen et al. (2016) clearly showed that the two tribes are distantly related. Walden et al. (2020) confirmed the findings of Chen et al. and demonstrated that the Hillielleae is sister to a clade containing the Iberideae and Megacarpaeeae but remotely related to the Biscutelleae . However, Hendriks et al. (2022) showed that the Hillielleae is sister to the clade including the last three tribes and together are sister to the Anastaticeae .

Iberideae (2: 30). The tribe includes the primarily European Iberis L. (27 spp.) and Teesdalia (3 spp.). Only Warwick et al. (2010) included Teesdalia in their studies and showed it to form a sister clade to Iberis and thus placed both genera in the tribe Iberideae . In Hendriks et al. (2022), two species of Teesdalia and one of Iberis were sampled and the results showed them to be remotely related. Clearly a better sampling of Iberis ought to be done to check whether or not the two genera can be maintained in one tribe.