Category Archives: Systematics

The history of Systematics: Plants in Systema Naturae, 1758 (Part 7)

by Piter Kehoma Boll

We are approaching the end of the description of Linnaeus’ classification of Plants (see parts 1, 2, 3, 4, 5 and 6). Today I’ll show two more classes, the last two of plants with mainly hermaphrodite flowers.

19. Syngenesia (“same generation”)

“Husbands composed of a generative compact”, i.e., the stamens are united, forming a cylinder.

19.1 Syngenesia Polygamia Aequalis (“same generation, many equal marriages”), compound flowers formed by several small compact flowers, all having stamens and pistils: Scolymus (golden thistles), Cichorium (chicories), Catananche (cupid’s darts), Hypochaeris (cat’s ears), Andryala (andryalas), Tragopogon (goatsbeards), Picris (oxtongues), Leontodon (hawkbits and dandelions), Sonchus (sow thistles), Scorzonera (salsifies), Crepis (hawksbeards), Chondrilla (skeletonweeds), Prenanthes (rattlesnake roots), Lactuca (lettuces), Hieracium (hawkweeds), Lapsana (nippleworts), Hyoseris (hyoserises), Elephantopus (elephant’s foot), Atractylis (spindle thistles), Carlina (carline thistles), Cnicus (thistles), Arctium (burdocks), Carthamus (distaff thistles), Cynara (alcachofras), Carduus (more thistles), Onopordum (cotton thistles), Serratula (plumeless saw-worts), Echinops (globe thistles), Ageratum (whiteweeds), Cacalia (false plantains), Chrysocoma (goldenhairs), Eupatorium (thoroughworts), Santolina (cotton lavenders), Bidens (beggarticks), Staehelina (staehelinas), Stoebe (stoebes), Tarchonanthus (camphor bush).

1758Linnaeus_syngenesia_polygamia_aequalis

The diverse order Syngenesia Polygamia Aequalis included (from left to right, top to bottom) the common goatsbeard (Tragopogon porrifolius), black salsify (Scorzonera hispanica), bristly oxtongue (Picris echioides, now Helminthotheca echioides), common sowthistle (Sonchus oleraceus), garden lettuce (Lactuca sativa), rush skeletonweed (Chondrilla juncea), common rattlesnake root (Prenanthes purpurea), common dandelion (Leontodon taraxacum, now Taraxacum officinale), rattlesnake hawkweed (Hieracium venosum), beaked hawksbeard (Crepis vesicaria), common andryala (Andryala integrifolia), smooth hyoseris (Hyoseris scabra), common cat’s ear (Hypochaeris radicata), common nipplewort (Lapsana communis), blue cupid’s dart (Catananche caerulea), common chicory (Cichorium intybus), Spanish golden thistle (Scolimus hispanicus), smooth elephant’s foot (Elephantopus scaber), great globe thistle (Echinops sphaerocephalus), great burdock (Arctium lappa), dyer’s plumeless saw-wort (Serratula tinctoria), musk thistle (Carduus nutans), holy thistle (Cnicus benedictus, now Centaurea benedicta), common cotton thistle (Onopordum acanthium), globe artichoke (Cynara scolymus), common carline thistle (Carlina vulgaris), common spindle thistle (Atractylus huilis), safflower (Carthamus tinctorius), common beggartick (Bidens pilosa), Alpine plantain (Cacalia alpina, now Adenostyles alpina), tall thoroughwort (Eupatorium altissimum), common whiteweed (Ageratum conyzoides), dubious staehelina (Staehelina dubia), common goldenhair (Chrysocoma coma-aurea), camphor bush (Tarchonanthus camphoratus), and common cotton lavender (Santolina chamaecyparissus). Credits to Stephen Lea (goatsbeard), H. Zell (salsify, lettuce, cotton thistle), Tony Wills (sow thistle), Radio Toreng (skeletonweed), Jane Shelby Richardson (hawkweed), Manfred Moitzi (hawksbeard), Pablo Alberto Salguero Quilles (andryala), smooth hyoseris (Hyoseris scabra), Javier Martin (hyoseris, spindle thistle), Phil Sellens (nipplewort), Isidre Blanc (cupid’s dart, staehelina), Joaquim Alves Gaspar (chicory, golden thistle, globe artichoke), Dinesh Valke (elephant’s foot), Enrico Blasutto (burdock), Kristian Peters (plumeless saw-wort), Bernd Haynold (musk thistle), Philipp Weigell (carline thistle), Vishesh Bajpai (beggartick),Benjammin Zwittnig (Alpine plantain), Frank Mayfield (thoroughwort), Peter A. Mansfeld (goldenhair), Paul Venter (camphor bush), Marie-Lan Nguyen (cotton lavender), and Wikimedia users AnemoneProjectors (oxtongue, cat’s ear), Calimo (rattlesnake root), Kropsoq (dandelion), Epp (globe thistle), 00temari (holy thistle), Pseudoanas (safflower) and Leoadec (whiteweed).*

19.2 Syngenesia Polygamia Superflua (“same generation, many remaining marriages”), compound flowers formed by several small compact flowers forming a central disk of hermaphrodite flowers surrounded by a ring of feminine flowers. Both hermaphrodite and feminine flowers are fertile and produce seeds: Tanacetum (tansies), Artemisia (artemisias), Gnaphalium (cudweeds), Xeranthemum (dry everlastings), Carpesium (carpesiums), Baccharis (baccharises), Conyza (horseweeds), Erigeron (fleabanes), Tussilago (coltsfoots), Senecio (ragworts and groundsels), Aster (asters), Solidago (goldenrods), Inula (inulas), Arnica (arnicas), Doronicum (leopard’s banes), Helenium (sneezeweeds), Bellis (daisies), Tagetes (marigolds), Zinnia (zinnias), Pectis (cinchweeds), Chrysanthemum (chrysanthemums and daisies), Matricaria (chamomiles), Cotula (water buttons), Anacyclus (anacycles), Anthemis (false chamomiles), Achillea (yarrows), Tridax (coatbuttons), Amellus (amelluses), Sigesbeckia (St. Paul’s worts), Verbesina (crownbeards), Tetragonotheca (neverays), Buphthalmum (ox-eyes).

1758Linnaeus_syngenesia_polygamia_superflua

Linnaeus put this species in the order Syngenesia Polygamia Superflua (from left to right, top to bottom): common tansy (Tanacetum vulgare), wormwood (Artemisia absinthium), heath cudweed (Gnaphalium sylvaticum), annual dry everlasting (Xeranthemum anuum), saltbush (Baccharis halimifolia), one-flower fleabane (Erigeron uniflorus), common coltsfoot (Tussilago farfara), common groundsel (Senecio vulgaris), Italian aster (Aster amellus), seaside goldenrod (Solidago sempervirens), hairy inula (Inula hirta), mountain arnica (Arnica montana), common leopard’s bane (Doronicum pardalianches), common sneezeweed (Helenium autumnale), common daisy (Bellis perennis), French marigold (Tagetes patula), Peruvian zinnia (Zinnia peruviana), Indian chrysanthemum (Chrysanthemum indicum), common chamomile (Matricaria chamomilla), buttonweed (Cotula coronopifolia), common anacycle (Anacyclus valentinus), sea false-chamomile (Anthemis maritima), common yarrow (Achillea millefolium), coatbuttons (Tridax procumbens), eastern St. Paul’s wort (Siegesbeckia orientalis), ox-eye (Buphthalmum salicifolium>). Credits to Muriel Bendel (tansy), Hermann Schachner (cudweed), Musa Geçit (dry everlasting), Bob Peterson (saltbush, coatbuttons), André Karwath (coltsfoot, daisy), C T Johansson (aster), Sam Fraser-Smith (goldenrod), Kurt Stüber (inula), Isidre Blanc (arnica), Agnieszka Kwiecien (sneezeweed), Lynda Poulter (chamomile), Walter Siegmund (buttonweed), Denis Barthel (false-chamomile), Petar Milošević (yarrow), and Wikimedia users N-Baudet (wormwood), Ghislain118 (fleabane), AnRo0002 (groundsel), Jamain (leopard’s bane, ox-eye), Rasbak (marigold), Vengolis (zinnia), Joydeep (chrysanthemum), Philmarin (anacycle) and Elouanne (St. Paul’s wort).

19.3 Syngenesia Polygamia Frustranea (“same generation, many marriages in vain”), compound flowers formed by several small compact flowers forming a central disk of hermaphrodite flowers surrounded by a ring of neutral flowers, without sexual organs, therefore only the flowers of the disk are fertile and produce seeds: Helianthus (sunflowers), Rudbeckia (black-eyed-susans), Coreopsis (coreopsises), Gorteria (gorterias), Centaurea (knapweeds), Gundelia (gundelia).

1758Linnaeus_syngenesia_polygamia_frustranea

The order Syngenesia Polygamia Frustranea included (from left to right) the common sunflower (Helianthus annuus), common black-eyed susan (Rudbeckia hirta), lance-leaved coreopsis (Coreopsis lanceolata), bachelor’s button (Centaurea montana), gundelia (Gundelia tournefortii). Credits to Frank Mayfield (black-eyed susan), Jean-Pol Grandmont (bachelor’s button), Gundelia (gundelia) and Wikimedia users i_am_jim (sunflower) and KENPEI (coreopsis).*

19.4 Syngenesia Polygamia Necessaria (“same generation, many unavoidable marriages”), compound flowers formed by several small compact flowers forming a central disk of hermaphrodite flowers, but whose feminine part is sterile, surrounded by a ring of fertile feminine flowers, therefore only the flowers of the ring produce seeds: Milleria (millerias), Silphium (rosinweeds), Chrysogonum (golden knees), Melampodium (blackfoots), Calendula (pot marigolds), Arctotis (bear’s ears), Osteospermum (daisybushes), Othonna (othonnas), Polymnia (leafcups), Eriocephalus (snow bushes), Filago (cudweeds), Micropus (cotton seeds), Sphaeranthus (ballflowers).

1758Linnaeus_syngenesia_polygamia_necessaria

These 7 species were included by Linnaeus in the order Syngenesia Polygamia Necessaria (from left to right, top to bottom): starry rosinweed (Silphium asteriscus), common golden knee (Chrysogonum virginianum), common pot-marigold (Calendula officinalis), whiteflower leafcup (Polymnia canadensis), Cape snow bush (Eriocephalus africanus), common cudweed (Filago germanica, now Filago vulgaris), Indian ballflower (Sphaeranthus indicus). Credits to James H. Miller (rosinweed), Fritz Flohr Reynolds (golden knee, leafcup), Wouter Hagens (pot marigold), Juanita Vilas Marchant (snow bush), Wim Rubers (cudweed), Dinnesh Valke (balflower).*

19.5 Syngenesia Monogamia (“same generation, one marriage”), stamens united forming a cylinder, but with single flowers, not forming inflorescences: Seriphium (seriphiums), Corymbium (plampers), Jasione (scabiouses), Lobelia (lobelias), Viola (violets and pansies), Impatiens (balsams).

1758Linnaeus_syngenesia_monogamia

The sheep’s scabious (Jasione montana, left), garden lobelia (Lobelia erinus, center left), common violet (Viola odorata, center right), and garden balsam (Impatiens balsamina, right) were part of the order Syngenesia Monogamia. Credits to André Karwath (lobelia), Bernard Dupont (violet) and Wikimedia users Darkone (scabious) and Joydeep (balsam).*

20. Gynandria (“female husband”)

“Husbands monstruously united to women”, i.e., flowers with stamens united to the pistils.

20.1 Gynandria Diandria (“female husband, two husbands”), two stamens united to the pistils: Orchis (orchids), Satyrium (satyre orchids), Ophrys (fly and bee orchids), Serapias (Serapis orchids), Limodorum (grass pinks), Arethusa (dragon’s mouth and snake’s mouths), Cypripedium (lady’s slippers orchids), Epidendrum (epiphytic orchids).

 

1758Linnaeus_gynandria_diandria

The order Gynandria Diandria included (from left to right, top to bottom) the military orchid (Orchis militaris), fly orchid (Ophrys insectifera), tuberous grass pink (Limodorum tuberosum, now Calopogon tuberosus), dragon’s mouth (Arethusa bulbosa), yellow lady’s slipper (Cypripedium calceolus), spathulate vanda (Epidendrum spathulatum, now Taprobanea spathulata). Credits to Holger Krisp (military orchid, fly orchid), Chris Meloche (dragon’s mouth), and Wikimedia users Algirdas (lady’s slipper) and CyberWikipedian (vanda).*

20.2 Gynandria Triandria (“female husband, three husbands”), three stamens united to the pistils: Sisyrinchium (blue-eyed grasses).

20.3 Gynandria Tetrandria (“female husband, four husbands”), four stamens united to the pistils: Nepenthes (pitcher plants).

20.4 Gynandria Pentandria (“female husband, five husbands”), five stamens united to the pistils: Ayenia (ayenias), Passiflora (passion flowers).

1758Linnaeus_gynandria_triandria_tetrandria_pentandria

The common blue-eyed grass (Sisyrinchium bermudianum, left) was the only member of the order Gynandria Triandria. The distiller pitcher-plant (Nepenthes distillatoria, center) was the only member of the order Gynandria Tetrandria. The purple passion flower (Passiflora incarnata) was one of the members of the order Gynandria Pentandria. Credits to Wouter Hagens (blue-eyed grass), James & Jana Hans (pitcher-plant), Oliver P. Quillia (passion flower).*

20.5 Gynandria Hexandria (“female husband, six husbands”), six stamens united to the pistils: Aristolochia (pipevines), Pistia (water lettuce).

20.6 Gynandria Decandria (“female husband, ten husbands”), ten stamens united to the pistils: Helicteres (screw trees).

1758Linnaeus_gynandria_hexandria_decandria

The order Gynandria Hexandria included the smearwort (Aristolochia rotunda, left) and the water lettuce (Pistia stratiotes, center). The order Gynandria Decandria included the Indian screw tree (Helicteres isora, right). Credits to J. M. Garg (screw tree) and Wikimedia users Hectonichus (smearwort) and Keisotyo (water lettuce).*

20.7 Gynandria Polyandria (“female husband, many husbands”), many stamens united to the pistils: Xylopia (xylopias), Grewia (crossberries), Arum (arums), Dracontium (arum yams), Calla (callas), Pothos (pothos), Zostera (eelgrasses).

1758Linnaeus_gynandria_polyandria

The order Gynandria Polyandria included (from left to right) the crossberry (Grewia occidentalis), dragon arum (Arum dracunculus, now Dracunculus vulgaris), elephant-foot yam (Dracontium polyphyllum, now Amorphophallus paeoniifolius), wild calla (Calla palustris) and climbing pothos (Pothos scandens). Credits to P. Pickaert (arum), Kurt Stüber (calla), and Wikimedia users Consultaplantas (crossberry), Fotokannan (yam) and Vinayaraj (pothos).*

As you can see, the class Syngenesia is much more regular than the class Gynandria. Most species of Syngenesia are currently included in the family Asteraceae. Gynandria, on the other hand, includes a variety of unrelated plants, including orchids, arum plants and even passion flowers!

Here we finish all plants with hermaphroditic flowers. We only need to more posts and we will have seen the whole system of Linnaeus!

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References:

Linnaeus, C. (1758) Systema Naturae per regna tria Naturae…

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The hammerhead flatworms: once a mess, now even messier

by Piter Kehoma Boll

Few people know that land planarians exist, but when they do, they most likely know the hammerhead flatworms, which comprise the subfamily Bipaliinae.

The hammerhead flatworms, or simply hammerhead worms, have this name because their head has lateral expansions that make them resemble a hammer, a shovel or a pickaxe. Take a look:

Bipalium_vagum

The “wandering hammerhead worm”, Bipalium vagum. Notice the peculiar head. Photo by flickr user budak.*

The Chinese knew the hammerhead worms at least since the 10th century, which is understandable, since they are distributed from Japan to Madagascar, including all southern and southeast Asia, as well as Indonesia, the Philippines and other archipelagos. The western world, however, first heard of them in 1857, when William Stimpson described the first species and put them in a genus called Bipalium, from Latin bi- (two) + pala (shovel), due to the head shape. One of them was the species Bipalium fuscatum, a Japanese species that is currently considered the type species of the genus.

800px-bipalium_fuscatum_by_head

Anterior region of Bipalium fuscatum, the “brownish hammerhead worm”. Photo by Wikimedia user 根川大橋.**

Two years later, in 1859, Ludwig K. Schmarda described one more species, this one from Sri Lanka, and, unaware of Stimpson’s paper, called the species Sphyrocephalus dendrophilus, erecting the new genus for it from Greek sphȳra (hammer) + kephalē (head).

Sphyrocephalus_dendrophilus

Drawings by Schmarda of Sphyrocephalus dendrophilus.

In the next year, 1860, Edward P. Wright did something similar and described some hammerhead worms from India and China, creating a new genus, Dunlopea, for them. The name was a homage to his friend A. Dunlop (whoever he was).

Dunlopea_grayia

Wright’s Drawing of Dunlopea grayia (now Diversibipalium grayi) from China.

Eventually those errors were perceived and all species were put in the genus Bipalium, along with several others described in the following years. All hammerhead worms were part of the genus Bipalium until 1896, when Ludwig von Graff decided to improve the classification and divided them into three genera:

1. Bipalium: With a head having long “ears”, a well developed head.
2. Placocephalus (“plate head”): With a more semicircular head.
3. Perocephalus (“mutilated head”): With a shorter, rudimentary head, almost as if it had been cut off.

Bipaliids

Compare the heads of typical species of Bipalium (left), Placocephalus (center) and Perocephalus (right), according to Graff.

This system, however, was soon abandoned and everything went back to be simply Bipalium and continued that way for almost a century, changing again only in 1998, when Kawakatsu and his friends started to mess with the penises of the hammerhead worms.

First, in 1998, they erected the genus Novibipalium (“new Bipalium“) for species with a reduced or absent penis papilla, and retained in Bipalium those with a “well”-developed penis papilla. It is worth noticing though that this well-developed papilla is not much bigger than a reduced papilla in Novibipalium. In both genera the actual, functional penis is formed by a set of folds in the male atrium and not by the penis papilla itself as in other land planarians that have a penis papilla.

Later, in 2001, Ogren & Sluys separated some more species of Bipalium in a new genus called Humbertium (after Aloïs Humbert, who described most species of this new genus). They were separated from Bipalium because the ovovitelloducts (the ducts that conduct the eggs and vitellocites) enter the female atrium from ahead, and not from behind as in the typical Bipalium. This separation is, in my opinion, more reasonable than the previous one.

Now we had three genera of hammerhead worms based on their internal anatomy, but several species were described without any knowledge of their sexual organs. Thus, in 2002, Kawakatsu and his friends created one more genus, Diversibipalium (the “diverse Bipalium“) to include all species whose anatomy of the sexual organs was unknown. In other words, it is a “wastebasket” genus to place them until they are better studied.

Are these three genera, Bipalium, Novibipalium and Humbertium, as now defined, natural? We still don’t know, but I bet they are not. A good way to check it would be by using molecular phylogeny, but we don’t have people working with these animals in their natural habitats, so we do not have available material for that. Another thing that can give us a hint is to look at their geographical distribution. We can assume that genetically similar species, especially of organisms with such a low dispersal ability as land planarians, all occur in the same geographical region, right? So where do we find species of each genus? Let’s see:

Bipalium: Indonesia, Japan, China, Korea, India.

Novibipalium: Japan.

Humbertium: Madagascar, Sri Lanka, Southern India, Indonesia.

Weird, right? They are completely mixed and covering a huge area of the planet, especially when we consider Humbertium. We can see a tendency, but nothing very clear.

Fortunately, some molecular analyses were published (see Mazza et al. (2016) in the references). One, which included the species Bipalium kewense, B. nobile, B. adventitium, Novibipalium venosum and Diversibipalium multilineatum placed Diversibipalium multilineatum very close to Bipalium nobile, and they are in fact very similar, so I guess that we can transfer it from Diversibipalium to Bipalium, right? Similary, Novibipalium venosum appears mixed with the species of Bipalium. I guess this is kind of messing things up one more time.

681px-bipalia_invasive

Head of some species of Bipalium, including the ones used in the study cited above. Unfortunately, I couldn’t find a photo or drawing of Novibipalium venosum. Image by myself, Piter Kehoma Boll.**

Interestingly, among the analyzed species, the most divergent was Bipalium adventitium, whose head is “blunter” than that of the other ones. Could the head be the answer, afterall? Let’s hope that someone with the necessary resources is willing to solve this mess soon.

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See also:

Once found and then forgotten: the not-so-bright side of taxonomy.

The lack of taxonomists and its consequences on ecology.

They only care if you are cute. How charisma harms biodiversity.

The faboulous taxonomic adventure of the genus Geoplana.

Darwin’s Planaria elegans: hidden, extinct or misidentified?

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References:

Graff, L. v. (1896) Über das System und die geographische Verbreitung der Landplanarien. Verhandlungen der Deutschen Zoologischen Gesellschaft6: 61–75.

Graff, L. v. (1899) Monographie der Turbellarien. II. Tricladida Terricola (Landplanarien). Engelmann, Leipzig.

Kawakatsu, M.; Ogren, R. E.; Froehlich, E. M. (1998) The taxonomic revision of several homonyms in the genus Bipalium, family Bipaliidae (Turbellaria, Seriata, Tricladida, Terricola). The Bulletin of Fuji Women’s College Series 236: 83–93.

Kawakatsu, M.; Ogren, R. E.; Froehlich, E. M., Sasaki, G.-Y. (2002) Additions and corrections of the previous land planarians indices of the world (Turbellaria, Seriata, Tricladida, Terricola). The bulletin of Fuji Women’s University. Ser. II40: 162–177.

Mazza, G.; Menchetti, M.; Sluys, R.; Solà, E.; Riutort, M.; Tricarico, E.; Justine, J.-L.; Cavigioli, L.; Mori, E. (2016) First report of the land planarian Diversibipalium multilineatum (Makino & Shirasawa, 1983) (Platyhelminthes, Tricladida, Continenticola) in Europe. Zootaxa4067(5): 577–580.

Ogren, R. E.; Sluys, R. (2001) The genus Humbertium gen. nov., a new taxon of the land planarian family Bipaliidae (Tricladida, Terricola). Belgian Journal of Zoology131: 201–204.

Schmarda, L. K. (1859) Neue Wirbellose Thiere beobachtet und gesammelt auf einer Reise um die Erde 1853 bis 1857 1. Turbellarien, Rotatorien und Anneliden. Erste Hälfte. Wilhelm Engelmann, Leipzig.

Stimpson, W. (1857) Prodromus descriptionis animalium evertebratorum quæ in Expeditione ad Oceanum, Pacificum Septentrionalem a Republica Federata missa, Johanne Rodgers Duce, observavit er descripsit. Pars I. Turbellaria Dendrocœla. Proceedings of the Academy of Natural Sciences of Philadelphia9: 19–31.

Wright, E. P. (1860) Notes on Dunlopea. Annals and Magazine of Natural History, 3rd ser.6: 54–56.

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The history of Systematics: Plants in Systema Naturae, 1758 (Part 6)

by Piter Kehoma Boll

Finally a new post in the History of Systematic series. This is the sixth part of Linnaeus’ classification of plants. See parts 1, 2, 3, 4 and 5. Here, I’ll present two more classes which are characterized by having the stamens arising from a common base in the flower.

16. Monadelphia (“single brothers”)

“Husbands, or brothers, arising from one base”, i.e., the filaments of the stamens are fused in a single body.

16.1 Monadelphia Pentandria (“single brothers, five males”), five stamens fused into a single structure: Waltheria (gray mallows), Hermannia (hermannias), Bombax (cotton trees), Melochia (melochias).

1758Linnaeus_monadelphia_pentandria

These 5 species belonged Linnaeus’ Monadelphia Pentandria (from left to right): sleepy morning (Waltheria indica), three-leaved hermannia (Hermannia trifoliata), chocolateweed (Melochia corchorifolia), red cotton tree (Bombax aculeatum, now Bombax ceiba). Credits to J. M. Garg (sleepy morning), C. E. Timothy Paine (hermannia), Jeevan Jose (chocolatewed), Dinesh Valke (cotton tree).

16.2 Monadelphia Decandria (“single brothers, ten males”), ten stamens fused into a single structure: Connarus (Indian zebrawood), Geranium (geraniums), Hugonia (a species of doubtful identity).

1758Linnaeus_monadelphia_decandria

The above species were put by Linnaeus in the order Monadelphia Decandria: Indian zebrawood (Connarus monocarpus, left) and bigroot geranium (Geranium macrorhizum, right). Credits to Dinesh Valke (zebrawood) and Wikipedia user Hardyplants (geranium).

16.3 Monadelphia Polyandria (“single brothers, many males”), many stamens fused into a single structure: Stewartia (silky camellia), Napaea (glade mallow), Sida (fanpetals), Adansonia (baobabs), Pentapetes (gojikas), Gossypium (cottons), Lavatera (tree mallows), Malva (mallows), Malope (mallow worts), Urena (caesarweeds), Alcea (hollyhocks), Hibiscus (hibiscuses), Althaea (marshmallows), Camellia (camélia).

1758Linnaeus_monadelphia_polyandria

Linnaeus classified the above species as Monadelphia Polyandria (from left to right, top to bottom): common baobab (Adansonia digitata), arrowleaf fanpetal (Sida rhombifolia), glade mallow (Napaea dioica), common marshmallow (Althaea officinalis), common hollyhock (Alcea rosea), common mallow (Malva sylvestris), garden tree mallow (Lavatera thuringiaca), common caesarweed (Urena lobata), Levant cotton (Gossypium herbaceum), Chinese hibiscus (Hibiscus rosa-sinensis), gojika (Pentapetes phoenicea), silky camellia (Stewartia malacodendron), common camellia (Camellia japonica). Credits to Jeevan Jose (fanpetal), Pablo Alberto Salguero Quiles (marshmallow), Stan Shebs (hollyhock), Joanna Voulgaraki (mallow), Bob Peterson (caesarweed), H. Zell (cotton), Andrew Fogg (hibiscus), Frank Vicentz (camellia), Wikimedia users Atamari (baobab), Botaurus stellaris (tree mallow), Melburnian (silky camellia), flickr users peganum (glade mallow), Lalithamba (gojika).

17. Diadelphia (“two brothers”)

“Husbands originating from a double base, as well as a double mother”, i.e., the filaments of the stamens are gathered in two bodies.

17.1 Diadelphia Pentandria (“two brothers, five males”), two structures formed of five fused stamens: Monnieria (monnieria).

17.2 Diadelphia Hexandria (“two brothers, six males”), two structures formed of six fused stamens: Fumaria (fumitories).

17.3 Diadelphia Octandria (“two brothers, eight males”), two structures formed of eight fused stamens: Polygala (milkworts), Securidaca (safeworts).

1758Linnaeus_diadelphia_hexandria_octandria

The plant to the left, the common fumitory (Fumaria officinalis) was in the order Diadelphia Hexandria, while the plant to the right, the common milkwort (Polygala vulgaris), was in the order Diadelphia Octandria. Credits to Isidre Blanc (fumitory) e Radio Tonreg (milkwort).

17.4 Diadelphia Decandria (“two brothers, ten males”), two structures formed of ten fused stamens: Amorpha (false indigo), Ebenus (ebonies), Erythrina (coral trees), Spartium (brooms), Genista (more brooms), Lupinus (lupins), Anthyllis (kidney vetches), Aeschynomene (jointvetches), Piscidia (), Borbonia (cape gorses), Aspalathus (more cape gorses), Ononis (restharrows), Crotalaria (rattlepods), Colutea (bladder sennas), Phaseolus (beans), Dolichos (longbeans, lablab bean), Orobus (vetchlings), Pisum (peas), Lathyrus (more vetchlings), Vicia (vetches), Astragalus (milkvetches), Biserrula (more milkvetches), Phaca (even more milkvetches), Psoralea (some trefoils), Trifolium (clovers or trefoils), Glycyrrhiza (licorices), Hedysarum (sweetvetches), Coronilla (more vetches), Ornithopus (bird’s-foot), Scorpiurus (scorpion’s-tails), Hippocrepis (horseshoe vetches), Medicago (alfalfas), Trigonella (fenugreek and allies), Glycine (soybeans), Clitoria (pigeonwings), Robinia (locusts, caraganes, riverhemps), Indigofera (indigos), Ulex (gorses), Cicer (chickpea), Ervum (lentils, vetches), Cytisus (laburnums and even more brooms), Galega (galegas), Lotus (bird’s-foot-trefoils), Arachis (peanut).

1758Linnaeus_diadelphia_decandria

These 36 plants were included in the order Diadelphia Decandria (from left to right, top to bottom): coral bean (Erythrina herbacea), fishfuddle (Piscidia erythrina, now Piscidia piscipula), heart-shaped capegorse (Borbonia cordata, now Aspalathus cordata), weaver’s broom (Spartium junceum), dyer’s broom (Genista tinctoria), desert false-indigo (Amorpha fruticosa), Indian jointvetch (Aeschynomeme indica), blue rattlepod (Crotalaria verrucosa), field restharrow (Ononis arvensis), common kidney vetch (Anthyllis vulneraria), white lupin (Lupinus albus), bladder senna (Colutea arborescens), common bean (Phaseolus vulgaris), lablab bean (Dolichos lablab, now Lablab purpureus), common pea (Pisum sativum), hairy vetchling (Orobus hirsutus, now Lathyrus hirsutus), grass vetchling (Lathyrus nissolia), common vetch (Vicia sativa), Chickpea (Cicer arietinum), lentil (Ervum lens, now Lens culinaris), common laburnum (Cytisus laburnum, now Laburnum anagyroides), common gorse (Ulex europaeus), peanut (Arachis hypogaea), licorice (Glycyrrhiza glabra), scorpion vetch (Coronilla glauca), little white bird’s-foot (Ornithopus perpusillus), horseshoe vetch (Hippocrepis comosa), prickly scorpion’s-tail (Scorpiurus muricatus), alpine sweetvetch (Hedysarum alpinum), indigo (Indigofera tinctoria), common galega (Galega officinalis), Asian pigeonwing (Clitoria ternatea), common soybean (Glycine max), alpine milkvetch (Astragalus alpinus), white clover (Trifolium repens), Cretan ebony (Ebenus cretica). Credits to Everglades NPS (coral bean), Jon Richfield (capegorse), Bernd Haynold (dyer’s broom), Dinesh Valke (jointvetch), J. M. Garg (rattlepod), Kristian Peters (restharrow, vetch, bird’s-foot), Massimiliano Marcelli (lupin), Mauricio Laurente (bean), Bogdan Giuşcă (hairy vetchling), Carl Davies-CSIRO (chickpea), Christian Kooyman (lentil), Jean François Gaffard (laburnum), H. Zell (peanut), Carsten Niehaus (scorpion vetch), Isidre Blanc (horseshoe vetch), Hans Hillewaert (scorpion’s-tail, clover), Nicola Cocchia (galega), Tusli Bhagat (pigeonwing), Jörg Hempel (milkvetch), Rüdiger Kratz (ebony), flickr users jayeshpatil912 (fishfuddle) and Eskimo Potato (sweetvetch), Wikimedia users Hectonichus (weaver’s broom), AnRo0002 (false indigo, kidney vetch, bladder senna), Dalgial (lablab), Rasbak (pea), Sannse (grass vetchling), Rosser1954 (gorse), Pharaoh han (liquorice), Pancrat (indigo), vegetalist (soybean).

18. Polyadelphia (“many brothers”)

Husbands originating from more than two mothers, i.e., stamens are gathered in three or many bodies.

18.1 Polyadelphia Pentandria (“many brothers, five males”), more than two structures of five fused stamens: Theobroma (cacao and bay cedar).

18.2 Polyadelphia Icosandria (“many brothers, twenty males”), more than two structures of twenty fused stamens: Citrus (citrus fruits trees).

18.3 Polyadelphia Polyandria (“many brothers, many males”), more than two structures of many fused stamens: Hypericum (St. Johnswort), Ascyrum (St. Andrew’s cross).

1758Linnaeus_polyadelphia

The cacao tree (Theobroma cacao, left) was one of the members of the order Polyadelphia Pentandria; the citron (Citrus medica, middle left) was a member of the order Polyadelphia Icosandria; and the Balearic St. Johnswort (Hypericum balearicum, middle right) and the St. Andrew’s cross (Ascyrum hypericoides, now Hypericum hypericoides) were members of the order Polyadelphia Polyandria. Credits to H. Zell (cacao tree), Christer T Johansson (citron), Wikimedia user Eric in SF (St. Johnswort), Bob Peterson (St. Andrew’s cross).

With a few exceptions, most of the plants in these classes currently belong to the families Malvaceae and Fabaceae (Leguminosae) of flowering plants. I guess we still need three more posts on the plants and then we are done! I hope the next part won’t take so long.

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References:

Linnaeus, C. (1758) Systema Naturae per Regna Tria Naturae…

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They only care if you are cute: how charisma harms biodiversity

by Piter Kehoma Boll

Which of the two species shown below is more charismatic?

Tangara_chilensis

Tangara chilensis (Paradise Tanager). Photo by flickr user ucumari.*

854px-apocrypta_guineensis2c_volw-wyfie_op_f_sur2c_manie_vd_schijff_bt2c_f

Apocrypta guineensis (a fig wasp). Photo by Wikimedia user JMK.**

You probably would pick the first one. And if I’d ask you which one deserves more attention and efforts to be preserved, you would likely choose the bird as well, or at least most people would. But what is the problem with that? That’s what I am going to show you now.

As we all know, the protection of biological diversity is an important subject in the current world. Fortunately, there is an increase in campaigns promoting the preservation of biodiversity, but unfortunately they are almost always directed to a small subset of species. You may find organizations seeking to protect sea turtles, tigers, eagles or giant pandas, but can you think of anyone wanting to protect beetles? Most preservation programs target large and charismatic creatures, such as mammals, birds and flowering plants, while smaller and not-so-cute organisms remain neglected. And this is not only true in environments that included non-biologist people, but in all fields of research. And more than only leading to a bias in the protection of ecosystems, this preference leads to thousands of understudied species that could bring biotechnological revolutions to humandkind.

In an interesting study published this week in Nature’s Scientific Reports (see reference below), Troudet et al. analyzed the taxonomic bias in biodiversity data by comparing the occurrence of data on several taxonomic groups to those groups’ diversity. The conclusions are astonishing, although not that much surprising. The most charismatic groups, such as birds, are, one could say, overstudied, with an excess of records, while other, such as insects, are highly understudied. While birds have about 200 million occurences above the ideal record, insects have about 200 million below the ideal number. And the situation does not seem to have improved very much along the years.

41598_2017_9084_fig1_html

The bias in interest is clear. The vertical line indicates the “ideal” number of occurrences of each group. A green bar indicates an excess of occurrences, while a red bar indicates a lack of occurrences. Birds and Insects are on the opposite extremes, but certainly the insect bias is much worse. Figure extracted from Troudet et al. (2017).***

Aditionally, the study concluded that the main reason for such disparity is simply societal preference, i.e., the most studied groups are the most loved ones by people in general. The issue is really a simple matter of charisma and has little to do with scientific or viability reasons.

The only way to change this scenario is if we find a way to raise awareness and interest of the general public on the less charismatic groups. We must make them interesting to the lay audience in order to receive their support and increase the number of future biologists that will choose to work with these neglected but very important creatures.

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See also:

Once found and then forgotten: the not so bright side of taxonomy

The lack of taxonomists and its consequences on ecology

Unknown whereabouts: the lack of biogeographic references of species

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Reference:

Troudet, J.; Grandcolas, P.; Blin, A,; Vignes-Lebbe, R.; Legendre, F. (2017) Taxonomic bias in biodiversity data and societal preferences. Scientific Report 7: 9132. https://dx.doi.org/10.1038/s41598-017-09084-6

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How do new species form?

by Piter Kehoma Boll

A long, long time ago, I wrote two posts here about the definition of species, explaining briefly the most important horizontal and vertical species concepts. So we all agree that species exists, but how they emerge? How one species become two, or how one species become another?

The phenomenon by which it occurs is called speciation. Well, sort of… It all depends on how you define a species, actually (so be certain to have read the posts I mentioned above).

355px-simplified_sketch_of_a_speciation_event_-_journal-pone-0042970-g007

Model of a lineage splitting into two lineages that evolve independently and eventually become separated species. Extracted from Hawlitschek et al. (2012)*

Speciation is usually defined as the evolution of reproductive isolation, therefore it deals more with the concept of biological species, but also with the ecological concept and certainly needs some insights on the vertical concepts. If two populations are reproductively isolated, it means that the individuals of one of them are unable or unwilling to breed with those of the other. This usually arrives through genetic and ecological differences that lead to differences in behavior, morphology, physiology. And considering that, we can classify reproductive isolation into two groups: pre-zygotic and post-zygotic isolation.

In pre-zygotic isolation, the two species are reproductively isolated because they do not want or cannot mate and produce an zygote. This may happen simply because of different behaviors in which the two species occupy different places in the environment, mate at different times of the year or even because they are not sexually attracted to each other. There are several experiments using fruitflies that demonstrate how this may evolve pretty fast.

In the late 1980s, William R. Rice and George W. Salt separated individuals of Drosophila melanogaster depending on their preference for dark × light and wet × dry environments, allowing them to mate only with other specimens showing the same preferences. After several generations, the individuals of one group were unable to mate with those of other groups because of their strong habitat preferences, making them unlikely to interact. A similar experiment was performed by Diane Dodd using the species Drosophila pseudoobscura, in which one population was raised with starch as food and other with maltose as food. In this case, after several generations the flies showed a strong preference to mate with individuals of the same group and to reject those of the other group.

640px-drosophila_speciation_experiment-svg

Evolution of reproductive isolation in fruit flies of the species Drosophila pseudoobscura after several generations fed with different sugars.

Such speciation events are called ecological speciation and are also well-documented in the widl, especially regarding fish preferring different habitats, such as shallow × deep water or still × running water. Eventually the individuals will diverge into two groups that are ecologically isolated in the same environment and consequently become reproductively isolated as well.

Post-zygotic isolation is generally a more advanced form of isolation that indicates deep genetic divergences. This is more commonly associated with the notion of biological species and is based on the inability of the individuals of the two species to produce viable offspring. They may mate with each other and even produce a zygote, but this will be unable to developed into an embryo or the offspring will be sterile or otherwise unable to survive enough to breed. A classical example is the mule, the hybrid of a mare and a donkey that is usully sterile.

Equus

A mare, Equus ferus caballus (left), a donkey, Equus africanus asinus (right) and a mule (center). Photos by ‘Little Miss Muffit’ (flickr.com/people/42562654@N00)(mare), Adrian Pingstone (donkey) and Dario Urruty (mule).

In both forms of speciation mentioned above, reproductive isolation usually arises from the accumulation of small differences due to natural selection. This may be enhanced by two phenomena, pleiotropy and genetic hitchhiking.

Pleiotropy is the phenomen by which a single gene have influence over more than one phenotypic trait. For example, a gene that influences the shape of a bird’s bill may also make it change its diet and its song. Several human genetic diseases, such as phenylketonuria (PKU), are examples of pleiotropy.

579px-leghorn_frizzle_chicken

The frizzled trait in chickens, which makes the feather curl outward, also leads to delayed sexual maturity and decreased metabolism rate. Photo by flickr user Just chaos.*

Genetic hitchhiking, on the other hand, is the phenomenon by which a gene that is naturally selected carries neighbours genes that are in the same DNA chain with it. In fruitflies, for example, a gene that is linked to courtship behavior may be drawn with the gene linked to a digestive enzyme, so that flies that specialize in one kind of sugar have a different courtship behavior than others specialized in another sugar.

That’s all for now. In a future post, I’ll talk about the geographic and genetic variables in species formation.

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References and further reading:

Bolnick, D. I., Snowberg, L. K., Patenia, C., Stutz, W. E., Ingram, T. & Lau, O. L. 2009. Phenotype-dependent native habitat preference
facilitates divergence between parapatric lake and stream stickleback. Evolution, 63(8): 2004-2016.

Hendry, A. P.2009. Ecological speciation! Or the lack thereof? Canadian Journal of Fisheries and Aquatic Sciences, 66: 1383-1398.

Hoskin, C. J. & Higgie, M. 2010. Speciation via species interactions: the divergence of mating traits within species. Ecology Letters, 13: 409-420.

Maan, M. E., Hofker, K. D., van Alphen, J. J. M. & Seehausen, O. 2006. Sensory drive in cichlid speciation. The American Naturalist, 167(6):
947-954.

Nosil, P. 2008. A century of evolution: Ernst Mayr (1904-2005). Ernst Mayr and the integration of geographic and ecological factors in
speciation. Biological Journal of the Linnean Society, 95: 26-46.

Turelli, M., Barton, N. H. & Coyne, J. A. 2001. Theory and speciation. TRENDS in Ecology and Evolution, 16(7): 330-343.

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Shaking dinosaur hips and messing with their heads

by Piter Kehoma Boll

This week brought astonishing news regarding the phylogeny of dinosaurus, as you perhaps have heard or read. New anatomical evidences have completely rebuilt the basis of the dinosaur family tree and I’m here to explain a little bit of what happened.

As we all know, Dinosaurs include a great variety of beasts, from the meat-eating theropods to the long-necked sauropods and from the horned ceratopsians to the armored ankylosaurs, among many others.

largestdinosaursbysuborder_scale

Silhouette of a human compared to the largest known dinosaurs of each major group. Picture by Matt Martyniuk.*

For more than a century now, dinosaurus have been divided into two groups, called Ornithischia and Saurischia. Ornithischia (“bird-hipped”) includes dinosaurus whose pelvic bones are more similar to what is found in birds, with a pubis directed backward. Saurischia (“lizard-hipped”), on the other hand, have a pubis directed forward, as in reptiles in general. This grouped the theropods and the sauropods in the same group as Saurischia while other dinosaurus were grouped as Ornithischia. But birds are actually theropods, thus being lizard-hipped dinosaurus and not bird-hipped dinosaurus! Confusing, isn’t it? So let’s take a look at their hips:

Pelvic_bones

Comparison of the hips of a crocodile (Crocodylus), a sauropod (Diplodocus), a non-avian theropod (Tyrannosaurus), a bird (Apteryx), a thyreophoran (Stegosaurus), and an ornithopod (Iguanodon). Red = pubis; Blue = ischium; Yellow = ilium. Picture by myself, Piter K. Boll.**

As you can see, the primitive state, found in crocodiles, sauropods and early theropods, is a pubis pointing forward. A backward-pointing pubis evolved at least twice independently, both in more advanced theropods (such as birds) and the ornithischian dinosaurus. But could we be so certain that Tyrannosaurus and Diplodocus are more closely related to each other (forming a clade Saurischia) just because of their hips? Afterall, this is a primitive hip, so it is very unlikely to be a synapomorphy (a shared derived character). Nevertheless, it continued to be used as a character uniting sauropods and theropods.

A new paper published by Nature this week, however, showed new evidences that point to a different relationship of the groups. After a detailed analysis of the bone anatomy, Matthew G. Baron, David B. Norman and Paul M. Barrett have found 20 characters that unite theropods with ornithischians and not with sauropods. Among those we can mention the presence of a foramen (a hole) at the anterior region of the premaxillary bone that is inside the narial fossa (the depression of the bone that surrounds the nostril’s opening) and a sharp longitudinal ridge along the maxilla.

skulls

The skulls of both ornithischians and theropods (above) show an anterior premaxillary foramen in the narial fossa (shown in yellow) and and a sharp ridge on the maxilla (shown in green), as well as other characters that are not present in sauropodomorphs and herrerasaurids (below). Composition using original pictures by Carol Abraczinskas and Paul C. Sereno (Heterodontosaurus), Wikimedia user Ghedoghedo (Eoraptor and Herrerasaurus), and flickr user philosophygeek (Plateosaurus).**

In his blog Tetrapod Zoology, Dr. Darren Naish comments the new classification and points out some problems that arise with this new view. One of them is the fact that both theropods and sauropodomorphs have pneumatic (hollow) bones, while ornithischians do not. If the new phylogeny is closer to the truth, that means that pneumacity evolved twice independently or evolved once and was lost in ornithischians.

He also mentions that both ornithischians and theropods had hair-like or quill-like structures on their skin. In theropods this eventually led to feathers. Could this be another synapomorphy uniting these groups? Maybe… but when we think that pterosaurs also had “hairs”, one could also conclude that a “hairy” integumentary structure was already presented in the common ancestor of dinosaurus. In this case, perhaps, we only had not found it yet on sauropods. Now imagine a giant Argentinosaurus covered with feathers!

One concern that appeared with this new organization is whether sauropodomorphs would still be considered dinosaurs. The term “dinosaur” was coined by Richard Owen in 1842 to refer to the remains of the three genera known at the time, Iguanodon, Hylaeosaurus and Megalosaurus, the first two being ornithischians and the latter a theropod. As a consequence, the original definition of dinosaur did not include sauropods. Similarly, the modern phylogenetic definition of dinosaur was “the least inclusive clade containing Passer domesticus (the house sparrow) and Triceratops horridus“. In order to allow Brachiosaurus and his friends to continue sitting  with the dinosaurs, Baron et al. suggested to expand the definition to include Diplodocus carnegii. So, dinosaurus would be the least inclusive clade containing P. domesticusT. horridus and D. carnegii.

In this new family tree, the name Saurischia would still be used, but to refer only to the sauropodomorphs and some primitive carnivores, the herrerasaurids. The new clade formed by uniting theropods and ornithischians was proposed to be called Ornithoscelida (“bird-legged”), a name coined in 1870 to refer to the bird-like hindlimbs of both theropods and ornithopods (the subgroup of ornithischians that includes dinosaurs such as Iguanodon and the duck-billed dinosaurs).

What can we conclude with all that? Nothing will change if you are just a dinosaur enthusiast and do not care about what’s an ornithischian and a saurischian. Now if you are a phylogeny fan, as I am, you are used to sudden changes in the branches. Most fossils of basal dinosaurs are incomplete, thus increasing the problem to know how they are related to each other. Perhaps this new view will last, perhaps new evidence will change all over again the next week.

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ResearchBlogging.orgReferences and further reading:

Baron, M., Norman, D., & Barrett, P. (2017). A new hypothesis of dinosaur relationships and early dinosaur evolution Nature, 543 (7646), 501-506 DOI: 10.1038/nature21700

Naish, D. (2017). Ornithoscelida Rises: A New Family Tree for DinosaursTetrapod Zoology.

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New Species: March 11 to 20, 2017

by Piter Kehoma Boll

Here is a list of species described from March 11 to March 20. It certainly does not include all described species. Most information comes from the journals Mycokeys, Phytokeys, Zookeys, Phytotaxa, Zootaxa, International Journal of Systematic and Evolutionary Microbiology, and Systematic and Applied Microbiology, as well as journals restricted to certain taxa.

Cherax_warsamsonicus

Cherax warsamsonicus is a new crayfish from Indonesia.

SARs

Plants

Fungi

Flatworms

Annelids

Rotifers

Tardigrades

Arachnids

Myriapods

Crustaceans

Insects

Cartilaginous fishes

Ray-finned fishes

Lissamphibians

Reptiles

Mammals

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