Alwisia lloydiae

The myxomycete now known as Alwisia lloydiae was one of the very first slime moulds I photographed. On August 17 2010 immature sporangia appeared on a large, strongly decayed eucalypt stump not far from our house.


Being conveniently located, I was able to capture its change in colour from creamy white to light and mid brown as the fruiting bodies matured. My interest in myxos was in its infancy; I was rarely collecting but was taking numerous field photographs especially of invertebrates (mostly collembola) feeding on the plasmodia and maturing fruits. This changed when I realised that, unlike fungi, species rarely reappear in exactly the same location, at least not in consecutive years.

slime-moulds-049
Acanthanura sp. (a collembola or springtail) feeding on A. lloydiae.

The species appeared again in August 2011 on a bryophyte-covered log on big tree track. I collected the specimen and attempted to identify it using Poulain et al., Stephenson and Stempen (1994) and Martin and Alexopoulos (1969) (i.e. M&A). Somewhat unusually it seemed quite easy to identify because as well as its relatively long, sometimes coalescing stalks, it has bristles arising from the edge of the calyculus. However, the only species to display this very distinctive characteristic was Tubifera bombarda, a species known only from the tropics. Because it seemed an unlikely extension of its distribution (Tasmania being temperate rather than tropical) I wrote an article about it for the Fungimap Newsletter #48 January 2013.
Soon after the article was published I was contacted by Dr Steven Stephenson whose PhD student Dmitry Leontyev was working on the Reticulariaceae family. At the time the family included four genera: Dictydiaethalium, Lycogala, Reticularia and Tubifera. (Dictydiaethalium has recently been shown to belong elsewhere). They were almost certain my specimen was not Tubifera bombarda but a species new to science. Here’s the story …
Way back in 1873 Berkeley and Broome proposed Alwisia as a new (monotypic) genus in the Reticulariaceae family. They named a specimen from Ceylon Alwisia bombarda and described it as having sporothecae ‘seated together on a common stem’, not a feature of any genus in that family. Interestingly, M&A write that the the justification for establishing the genus Alwisia was that, when present, its pseudocapillitium is ‘very striking’. It is very surprising, therefore, that this most distinctive feature was not mentioned in the original description but was added by another author, G. Massee, in 1889. (Massee renamed the species Prototrichia bombarda in 1892.)
In 1961 G.W Martin (the ‘M’ of M&A), proposed uniting two genera from the Reticulariaceae family – Alwisia and Tubifera – based on the similar structures of their sporothecae, ‘which are united into compound frutifications (psedudoaethalia) in both cases’. ‘Alwisia‘ was scrapped and the species name was changed to Tubifera bombarda.
In 1963 an undescribed species collected in Costa Rica was identified as T. bombarda by Alexopoulos (the ‘A’ of M&A). This was despite its lack of the distinctive capillitium and other features characteristic of the species. They simply broadened the diagnosis of T. bombarda to include those collections that had either no threads, a few threads or rudimentary threads.
In 1998, 2001 and 2008 more specimens were collected in Costa Rica and in 2008 a similar-looking slime mould was collected in New South Wales (Australia). They did not fit the diagnosis of T. bombarda – or any other genus in the Reticulariaceae family. Furthermore, researchers, after sequencing the first part of the SSU rRNA gene of thirteen species in the Reticulariaceae family, found that the specimens did not belong to any known genera and a new genus was required. Because Alwisia had already been proposed for one species, the name was revalidated. The new genus included three species: A. bombarda, A. morula (from Costa Rica) and A. repens (collected by fellow fungimapper Terese Van Der Huel from NSW). (Leontyev et al. 2014)
Meanwhile, while the paper describing the revalidation of Alwisia with two new species was being prepared for publication, my specimen was on its way to the USA for genetic sequencing. (Specimens of A. lloydiae were also collected in NSW by Dr Steven Stephenson.) The researchers determined that it was different enough both genetically and morphologically to be considered a new species: Alwisia lloydiae.  (Leontyev et al. 2014)
The story doesn’t stop there. In a paper ‘Evolution of sporophore in Reticulariaceae’, researchers concluded that there was a tendency for species in the family to evolve from stalked separate sporangia (e.g. A. lloydiae) to sessile closely-packed sporangia that form either an aethalium or pseudoaethalium (e.g. Reticularia and Tubifera species). Furthermore, they found that the closest species to the common ancestor of the family was similar to A. lloydiae and noted that ‘this species occurs in the Australian continent and in Tasmania, the well known refuges of relict biota’. (Leontyev et al, 2016)

a-lloydiae-reduced
Alwisia lloydiae

After an absence of several years, Alwisia lloydiae appeared on four large eucalypt logs 50 to 100 meters apart. Three of the logs are in very shaded areas of forest and are covered in bryophytes (moss and leafy liverworts), but the fourth is in a relatively open area about 20 meters from our house.  Like other members of the genus, Alwisia lloydiae appears in extensive groups on severely decayed wood that is often covered in bryophytes.

Post script: People sometimes ask me how I feel about having a slime mould named after me.

As a naturalist my preference (especially for flowering plants) is for the specific epithet to be descriptive in some way as it assists identification. However, myxos are among the least studied of all microorganisms, so a descriptive name would not assist many people. I find it gratifying to be honoured in such a way and to join a small dedicated group of people who have also been thus honoured.

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