Clarification of Pterostylis valida

Short Paper 3 Identity of Pterostylis valida (Orchidaceae) by Rudie Kuiter was published in June 2017. In this paper, Rudie has tackled the difficult group of Rustyhoods or Oliogochaetochilus (specifically Pterostylis valida) within the genus Pterostylis. Many of the different species occur in isolated pockets over a wide geographical range. Differences can be subtle but Rudie has sought to clarify the distinction between P. valida  and similar species. Click here read the complete paper.

A typical flower at the type-locality, green with the usual stripes on the transparent parts of the hood, cup-shaped synsepalum and dark labellum swellings. Opposite page Image of the original 1941 description page by Nicholls of Pterostylis valida as a variety of P. squamata. It was cropped with the deletion of the description of Caladenia hastata, the other species. 
A typical flower at the type-locality, green with the usual stripes on the transparent parts of the hood, cup-shaped synsepalum and dark labellum swellings. (Image from Rudie Kuiter’s Short Paper)

 

Tracking Down the elusive Prasophyllum suttonii

Rudie Kuiter’s Short Paper 2 Taxonomic Status of the Mauve Leek-orchid Prasophyllum suttonii Rogers & Rees, 1912 (Orchidaceae) published in May 2017 documents how he used original source material to determine the identification of a species that was considered extinct.  Prasophyllum suttonii belongs to the Prasophyllum odoratum/diversiflorum complex and is very similar to the later named Prasophyllum alpestre. It was considered to be extinct but Rudie’s view was not that it was extinct but that it had been “lost in taxonomy, and its status need to be restored”. His article documents how he used original material to help determine identification of the species he had photographed.

In his summary Rudie has some good advice about how to effectively use the material available –

  • Use original descriptions and illustrations
    • Original descriptions are preferred over type specimens
    • later descriptions may be based upon second hand information which may or may not be accurate.
  • Drawings have some value but depend
    • upon the skill of the artist to show the crucial details
    • upon whether they were drawings from fresh or preserved specimens
  • A good photograph will be better than a drawing
  • Type material is useful but may deteriorate over time

Images from Rudie Kuiter's article on Prasophyllum suttonii

 

Click here to read the complete article

 

Pterostylis Pollinators

Rudie Kuiter et al have been observing orchid pollinators over many seasons spending hours watching and becoming familiar with pollinator interaction with the orchid, learning when to anticipate pollination activity.

Their observations of various Pterostylis species has been documented in Overview of Pterostylis Pollination (Orchidaceae) in Victoria. In all, they observed 53 Pterostylis species and 40 species of pollinators from several different genera. They noted that some pollinators species were active most of the day but others were only active in the late afternoon whilst others were “only seen on dusk and possibly are nocturnal as well”.

 

 

Introducing Orchid Pollinators of Victoria: Part One of Two Parts

This week’s blog, Part One of Two Parts, is quoted directly from the introductory chapter (Pages 2&3) Orchid Pollinators of Victoria 4th Edition, 2016, Rudie Kuiter.  Over the years of photographing orchids and their pollinators, Rudie and his team have been discovering much of the hidden world of orchid pollinators.  In this first section he highlights the fallacy of the “one orchid-one pollinator” as well as touching briefly on the vast difference between the insects and their role in the ecosystem.

Click here for Part Two

INTRODUCTION

Amongst flowering plants, orchids have evolved in their own special reproductive ways.  Their pollen is massed as waxy packages, pollinia, unlike like (sic) other flowers that produce masses of fine pollen grains that mostly go astray.  The pollinia are relatively heavy and the usually small creatures need to be strong fliers for cross pollination (see image below).  Orchids evolved with amazing strategies to attract specific carriers in order to transfer pollen between flowers of their species only, and in this way eliminating the need to produce great quantities.  Various insects, many moths, bees and even birds have been documented as pollinators of orchids around the world (v.d. Cingel, 2001).  A number of uniquely different examples of orchids attracting insects for their pollination evolved in Australia, especially in the more temperate southern zones originating from Gondwana times.  With very few exceptions the Victorian orchids are terrestrial, ground-dwellers, that rely on small insects such as fungus-gnats, native bees, wasps, ants and many attract only the males by sexual deception.  In the case no pollinators visits, many species may self-pollinate as a back up.

When taking an interest in orchids it seems difficult enough to identify some species.  Usually one looks and admires the amazing flowers that may resemble an insect and can be difficult to recognise as a flower at first.  An insect on a flower may be thought of something that spoils a picture – until taking an interest in the visitor!

160219 Anita Marquart Melangyna collatus on Caladenia rigida
Hoverfly on Caladenia rigida (syn Arachnorchis rigida)

I first learned about the orchid pollinators in Orchids of South Australia by Bates & Weber, 1990, an excellent book by today’s standard, but few were seen over the years by just being there at the right time when photographing orchids.  During preparation of the book on Caladenia spider-orchids, certain issues developed from questionable statements made in scientific papers about wasp-pollinators.  Of particular concern was about the one-to-one relationship – how only one wasp-species would be involved with only one spider-orchid species – and suggesting populations that were thought to represent the same species comprised different taxa if not pollinated by the same wasp-species.  A very different story emerged when monitoring the local spider-orchid populations to find the answers and it became clear that there was much more to it.  A site in Wonthaggi with a very large colony of Caladenia dilatata proved to be perfect for this study and also to photograph pollinators as it produces flowers for about four months.  It was found that a local wasp-pollinator species typically flies for a little over one month, thus this need to be investigated further.  Scientific publications on wasp-pollinators were generally based on short-term experiments, and usually employing baiting methods – moving flowers and often taking them to different sites.  Responses included unnatural behaviour or attracting sibling wasps at a non-local site.  It is certainly true that a particular flower may attract only one species of wasp a t a locality and a certain time in the season, but this reflects a very small part of the picture.  It can be different in the long-term, at certain localities or with a season.

The main study site was in coastal dunes, where in a very large population of Caladenia dilatata produced flowers for over four months from September, and under favourable Summer-conditions into January.  At least three congeneric (belonging to the same genus) thynniid wasps species were involved in this population.  The flying times were up to about 6 weeks for each wasp species, that were separated or slightly overlapping.  The flowering times in other populations of C. dilatata in Wonthaggi and Wilsons Promontory were usually about one month in each, and at the corresponding times to the study site the wasps visiting were the same species.  A close sibling C. parva in the Wonthaggi heathland habitats and early flowering C. dilatata were pollinated by the same species, but the later flowering C. tentaculata by a thynniid wasp of the different genus.

160219 Anita Marquart Melangyna collatus with pollinia
Hoverfly with pollinia

Whilst a flower may attract only one wasp species, the kairomones (chemical omitted by the orchid to attract a pollinator)  of a species may vary between flowers within in a population or when allopatric (growing in different geographical regions), just like colour or morphology.  Variations maybe in relation to locality, weather conditions, or ground chemistry and available pollinator.  Pollinators may evolve over time, but adaptions usually require many seasons and this would vary with location.  The observations made over several seasons suggest that more than one congeneric insect is involved in pollination depending on local or seasonal conditions, especially after a long drought.  Chiloglottis gunnii populations in Langwarrin were checked for pollinators since a decade-long drought and no action was seen for many seasons.  When wasps finally made an appearance they comprised different taxa of Neozeleboria the first season, but only one became the common and principal pollinator the following seasons.  Thynniid wasps are very localised as females lack wings and rely on the males to carry them around during copulation and to provide food.  It limits their travelling and their homing range may comprise just a few hundred metres.  Thynniid wasp are very vulnerable in small reserves isolated by land-clearing, and certain species have gone locally extinct due to conducting burns.  Insects form a crucial and fundamental part of an ecosystem, but their importance is never considered in the planned burning, showing a complete lack of understanding by people in charge.  So little is known of ecosystem’s foundations, but controlled burning continues – ruining precious habitats.  Orchid species failing to produce seed pods is an indication that pollinators were absent, probably gone locally extinct.  Orchid species that have a sexual association with thynniid wasp pollinators are localised and usually have geographically variable flowers.  The situation is different with Cryptostylis spp. And their pollinating male wasp Lissopimpla excelsa, as females are a strong flyers.  The flowers of Cryptostylis are geographically uniform in each species and the wasp is widespread.  Both sexes are very distinctive in colour that show no variation.  They are active over Spring and Summer and are great travellers.

To be continued …

Snapshot of Australian Orchid Conservation

Internationally, there is concern about the decline of orchids as seen in the resolutions passed in May 2016 at the International Orchid Conservation Congress Conference.  In Australia, there are many orchid conservation projects in progress both in situ and ex situ.

The following are some examples of the varied work being done around the country by volunteers, orchid enthusiasts, ecologists, conservationists, academics and government departments.

And here in South Australia there are also various projects. Dr Noushka Reiter is also working with the South Australian Seedbank to help propagate four of our very threatened orchids.  Members of the Native Orchid Society are assisting as also are Paul Beltrame (teacher) and students from Kildare College through the Orchid in Schools Project.

06 sm PM Arachnorchis argocalla

 

An Examination of Two Rufoushoods

This week’s post is taking a brief look at a paper by Noushka Reiter, Mark Clements and Kate Vlcek which appeared in Muelleria, Volume 31: 69 – 76, 2013.

Titled “An examination of Pterostylis xerophila (Orchidaceae) and the confirmation of P. lingua as a new species in Victoria” this paper seeks to ascertain whether the records collected are correctly identified, that there are differences between them both in morphology and associated vegetation.

Both P. xerophila and P. lingua are found in South Australia where they are known, respectively, by the synonyms Oligochaetochilus xerophilus and O. linguus. In fact the type specimen for O. xerophilus is from South Australia.

In the introduction, the authors give a detailed description of Oligochaetochilus otherwise known as the ‘rufa group’ which differs from Pterostylis, in the strict sense, in several features. Some of the main features of this group are:

  • Basal rosette of overlapping stemless leaves
  • Leaves senesced, withered and died, by flowering
  • Erect multi-flowered
  • Flowers
    • Lateral sepals
      • hang down
      • basal half joined
      • tips become long and threadlike
    • Labellum
      • is very mobile
      • has obvious long white hairs and often short hairs as well
Typical of the rufus hood this Oligochaetochilus arenicola shows the sencesing leaves, pendent petals and hairs on the labellum. Photographer: H Lawrence
Typical of the rufus hood, this Oligochaetochilus arenicola shows the sencesing leaves, pendent petals and hairs on the labellum.
Photographer: H Lawrence

Later in the articles, the differences between the two species are discussed. There is much of interest concerning the two species but one outcome of the research was to establish that P. lingua (O. linguus) had been incorrectly identified in the records and by correcting the names of the specimens the authors were able to confirm that it did occur in Victoria.

To find the answer to the authors other questions, read the paper

And for those that need a glossary of the terminology used, click here

For images of P. xerophila (O. xerophilus) click here

For images of P. lingua (O. linguus) click here