28.12.18 Brocks Hill: Lepidocyrtus - feeling the pain

A quick trip to a local wildlife area the relieve the monotony, a big bag of leaf litter - surely this is the true meaning of Christmas. And, like most Christmas presents, the contents of Santas sack turned out to be faintly underwhelming. Dicyrtomina saundersi - lots of them, they're everywhere at present. A single big, bouncy Orchesella villosa. And, inevitably, lots of Lepidocyrtus:




Every time I feel I'm making progress with Lepidocyrtus I immediately start to go backwards again. After an unproductive morning, I'm tempted to put this one down as Lepidocyrtus lanuginosus because I can see no evidence of scales on the legs or antennae, but frankly, I'm not at all confident. At least I know I'm not alone in struggling with this genus:

Mateos, E., Escuer, P., Buşmachiu, G., Riutort, M., & Álvarez-Presas, M. (2018) Untangling Lepidocyrtus (Collembola, Entomobryidae): new molecular data shed light on the relationships of the European groups. Invertebrate Systematics, 32(3), 639-651. https://doi.org/10.1071/IS17056
A redefinition of European species-groups is proposed based on chaetotaxy:
Lepidocyrtus curvicollis group
Lepidocyrtus lignorum group
Lepidocyrtus pallidus group
Lepidocyrtus lanuginosus group
Lepidocyrtus lusitanicus group

Zhang, B., Chen, T.W., Mateos, E., Scheu, S., & Schaefer, I. (2018) Cryptic species in Lepidocyrtus lanuginosus (Collembola: Entomobryidae) are sorted by habitat type. Pedobiologia, 68, 12-19. https://doi.org/10.1016/j.pedobi.2018.03.001
Lepidocyrtus lanuginosus separates into three major genetic lineages with one of these lineages being close to Lepidocyrtus cyaneus.

Anyway, a positive outcome in the end. Although I'm still unclear about the the identity of these specimens, I've seen the future and it's chaetotaxy:

17.12.18 - Cloud Wood

After the crazy summer of 2018, things are back on track.

Cloud Wood represents one of very few opportunities to get onto Carboniferous limestone in Leicestershire and is therefore of interest. Sadly, much of the former woodland has been removed by quarrying. I sampled leaf litter from two sites, starting near the edge of the quarried area. This was dominated by deep Oak litter, but also had many decaying Birch logs on the ground and on the logs, many large, dark springtails. These turned out to be Dicyrtomina saundersi - seemingly completely dominating the area. I've never seen as many springtails out in the open before, although I've heard several other reports of fences and gates with many D. saundersi on them from this period. A few years ago Peter Shaw commented on the seemingly unstoppable rise of Dicyrtomina saundersi - and there's no reason to believe that it's over:


(Shaw, P., et al (2013) Updating taxonomic biogeography in the light of new methods–examples from Collembola. Soil Organisms, 85(3), 161-170).

The only other springtails I found in this litter sample were also of interest - good numbers of Tomocerus minor as part of a young population with many juveniles. This was interesting because these were the first Tomiocerids I have recorded anywhere since 21.10.18!




I also sampled leaf litter from the other end of the site (a mixture of Sycamore, Oak and other species). This also turned up Dicyrtomina saundersi and Tomocerus minor, but in addition a good number of isotomids, some of which I tentatively identified as Desoria tigrina and Isotomurus unifasciatus, and definitely plenty of Vertagopus arboreus:

Wishing you a Collembola Christmas

With Monobella grassei baubles.

The Science Bit:
Luminescent springtails have been recognized in the families Neanuridae and Onychiuridae (Harvey, E.N. (1952) Bioluminescence. Academic Press; Haneda, Y. (1955) Luminous organisms of Japan and the Far East. The luminescence of biological systems), but the observations are quite limited. It is not clear whether collembolan luminescence is true bioluminescence (endogenous) or accidental due to ingestion of luminous bacteria or fungi. A Japanese springtail Lobelia spp. (Neanuridae) may be self-luminous. This species is ∼3 mm long, found in leaf litter and emits a continuous weak green light from abdominal tubercles. The biological function this luminescence is unknown, but it may be either for defence or sexual communication, since the luminescence is emitted on stimulation and also occurrs in the sexual phase (Lloyd, J.E. (1978) Insect bioluminescence. Bioluminescence in Action, 241-272).

12.12.18 - Attenborough Arboretum

I've never sampled springtails from the Attenborough Arboretum before, so a bag full of leaf litter was my first detailed look at this site. I was able to find five species, all in approximately equal numbers: Dicyrtomina ornata, Entomobrya nicoleti, Orchesella cincta and Orchesella villosa.

The major interest in this sample was Sminthurinus reticulatus, the first record of this species for VC55. I'm afraid this photo is not very good as I initially discounted this specimen as the very similar Sminthurinus aureus, but S. reticulatus is distinctively patterned with 3-4 transverse bands on the dorsal abdomen plus dark lateral bands which are discontinuous around the posterior end of the abdomen:



Interestingly, it is now weeks since I have seen any Tomocerids in any sample - is this a delayed reaction to the drought/heatwave of 2018?

Vertagopus Identification Guide

This is a very common genus of arboreal springtails with only two British species. They have no macrosetae but a fuzzy cover of short setae; clavate (forked) setae by the feet (for climbing trees).


Vertagopus arboreus:
- blus iridescence (in natural light, can be hard to see in artificial light)
- pale legs
- relatively short furca
- juveniles are violet in colour:





Specimen with damaged antennae:




Vertagopus cinereus:
- legs darker than Vertagopus arboreus and lacks blue iridescence
- shorter furcula than V. arboreus.
- On the ventral side of the thorax, 3-10 + 3-10 setae on each of th2 and th3, and a group of 5-12 ventral setae on the second abdominal segment (abd2). V. arboreus does NOT possess ventral setae on th2, th3 or abd2:

09.12.18 - Knighton

Having come up trumps with leaf litter samples recently, I popped out to the local churchyard for another Bag For Life full of leaf litter. In addition to bugs, centipedes, millipedes, spiders and woodlice, this also yielded abundant springtails. There were a number of Entomobrya multifasciata, mostly juveniles surprisingly, as well as other juvenile Entomobrya spp. whose identity I could not be sure of. I was a bit surprised to see such a juvenile population at this time of year. I also found a single Sminthurinus aureus (form maculatus - bilateral comma-shaped spots), a species I have recorded at this location previously, although then in the more typical golden form:




The standouts were good numbers of Dicyrtomina species. It is unusual for me to find them all in the same sample, this points to their abundance in leaf litter at present.

06.12.18 - Knighton Park

A bagful of leaf litter from the local park proved to be very productive. There were a good number of big, fat, dark Dicyrtomina saundersi and several Entomobrya nicoleti. There were also quite a few of the biggest and bounciest Orchesella villosa I have ever seen. A couple of Isotomids caused me some head scratching, but eventually I identified them as Desoria tigrina:



and Isotomurus palustris:




Most spectacular was a single Monobella grassei, the first time I have recorded this species in VC55:

Order Poduromorpha

Identified by a prominent Th1 segment, this group is common and widespread but most species are difficult to identify, hence they are mostly under recorded. Their small size means they are frequently overlooked:

Superfamily Hypogastruroidea
Family Hypogastruridae
Species in this family are difficult to identify, relying on features such as the internal structure of the mouthparts and anal spines. For this reason most people do not bother with them and I have so far made no positive identifications:

11.03.18 ~1mm in Beech leaf litter, roundish mouthcone, 2 anal spines:



Genus Hypogastrura - very short anal spines (c.f. Ceratophysella spp.) plus four-lobed post-antennal organ. 

More that 20 British "species" have been described in this genus, most of which are not valid as they are synonyms, misidentifications or based on a single historic specimen.  In the 2007 AIDGAP key, Steve Hopkin recognized nine UK species, three relatively common and the others rare. Unless microscopic evidence confirming the species is available they should be recorded as Hypogastrura spp. Separating these species is a two step process, first examining the numbers of clavate tenant seta on each tibiotarsus, followed by examination of the mucro, claw and empodium to confirm the species (the AIDGAP key has excellent comparative drawings of these features). The three common species are:

H.manubrialis: 111,  empodium tapers gradually and does not possess a lamella.

H. purpurescens: 232, mucro with bulge and empodium with lamella. 

H. viatica: 233, mucro with large bulge and empodium with lamella. 

Hypogastrura manubrialis

Hypogastrura manubrialis leg 3 - one clavate tenant seta

Hypogastrura manubrialis mucro

Superfamily Neanuroidea
Family Brachystomellidae
Genus Neanura - no furca - springless springtails:
Neanura muscorum. A very common blueish-purple springtail, usually found under bark on decaying wood. The eyes are highly distinctive with 3+3 ocelli. Pointed mouthcone, it lacks a furca. Easy to identify - the only UK species in this genus.






Genus Monobella
Monobella is a contraction of mono+lobella and refers to the single (transverse) lobe of the last body segment - c.f. Bilobella (2 posterior lobes).

Monobella grassei. A distinctive orange springtail with long body setae:







Family Poduridae
Genus Podura - Podura aquatica.
To follow.

Linea ventralis

Linea ventralis, a cuticular groove that transports secretions from the labial kidneys (Collembola do not have malpighian tubules as found in Insecta) to the tip of the collophore, where they can be discharged.

14.11.18 - Great Merrible

My first return to Great Merrible since 12.05.18. On that occasion I well remember having to beat a retreat - unstoppable sneezing and eyes streaming so that I couldn't focus on anything, the hayfever forced me to give up. This trip was much more fun - autumn colours and a pleasant temperature. I concentrated on looking for springtails in decaying wood. This turned up a few Pogonognathellus longicornis and a large number of Lepidocyrtus lignorum:




One piece of wet wood literally broke up in my hand and deep inside I found Neanura muscorum. This is regarded as a common species but is my first record for VC55:



This species has no furca - a springless springtail:




Great Merrible:

Katiannidae

Family Katiannidae

Genus Katianna: www.collembola.org - Katianna

To the best of my knowledge there have been four "species" of Katiannidae recorded in the UK. All seem to be associated with the horticultural industry and to have been imported from Australasia:

Katianna (nr) australis (Photo: Mark Horton):




Katianna (nr) schoetti (Photo: Edward Nurcombe):




Katiannidae genus nov.1 sp. nov. (with striped back):




Katiannidae genus nov.1 sp. nov.2 (with orange/red back):




Genus Sminthurinus: www.collembola.org - Sminthurinus
This is a very difficult group with nearly 100 described "species". Badly needs a thorough taxonomic revision.

Sminthurinus aureus is a very common terrestrial springtail, less than 1mm long. It is particularly abundant on the underside of fallen leaves in autumn (as are other globular species). As the names suggests, it has an overall golden colour with no clear banding. Sminthurinus aureus has the 'small abdomen' (the animal's "tail end") wholly fused, while other UK Sminthurinus have a visible division between segments 5 and 6. The fourth antennal segment (ant4) is not subdivided.



Female:




S. aureus comes in a variety of colour forms with varying degrees of dark pigment, e.g. form ochropus:



The entire Sminthurinus aureus group badly needs a taxonomic revision. A good example of this is Sminthurinus reticulatus. Although very similar to S. aureus,S. reticulatus is distinctively patterned with 3-4 transverse bands on the dorsal abdomen plus dark lateral bands which are discontinuous around the posterior end of the abdomen:



However, there is some confusion about the "true" Sminthurinus reticulatus (which DNA evidence supports as a separate species), and Sminthurinus aureus form reticulatus. The differences are said to be:

Sminthurinus reticulatus: transverse abdominal bands are the same dark colour as the lateral bands.
Sminthurinus aureus form reticulatus: transverse abdominal bands are paler than the lateral bands.

There are also reports about differences in the arrangement of the ocelli on the eyespot:

Sminthurinus aureus group (including form reticulatus): Ocelli C and D are distinctly smaller than the others (ABcdEFGH):


Sminthurinus reticulatus: Ocellus C is absent (ABdEFGH):


I have not yet been able to confirm this by observations.

Sminthurinus elegans form ornatus

Small (to 1mm) golden springtail with characteristic patter of four dark longitudinal bands on the abdomen - in this form the typical midstripe of S. elegans is lacking. Found in leaf litter and low vegetation in almost all terrestrial habitats, preferring drier areas than S. aureus.

Sminthurus viridis is a relatively large greenish or yellowish brown springtail reaching 3mm in length. The fourth antennal segment (ant4) is divided into 18 subsegments:


There are two variants of this species. Sminthurus viridis ssp. cinereoviridis has two spots on small abdomen:


In the ecovariant nigromaculatus of S. viridis, three spots are present: https://www.collembola.org/images/stach/1956/Sminthurus-viridis-1956-J-Stach-Poland-PlateXXXII-Fig3.jpg There are supposedly difference in chaetotaxy of the setae on the subcoxa of the third leg, but I have found it impossible to image these. Steve Hopkins was reluctant to accept nigromaculatus as a separate species. As a dyed-in-the-wool taxonomic lumper, I wouldn't disagree. Frans Janssens calls it "Sminthurus viridis ecovariant nigromaculatus", which is said to be associated with sandy areas, heathland, moors, heather, etc.
 

16.11.18 - Leicester Botanical Garden

I went back to Leicester Botanical Garden looking for male Entomobrya nigrocincta (no luck), but while I was there I found some interesting specimens. I started by sampling from a south facing Rosemary hedge (this meant I spent the rest of the day reeking of Rosemary, which was nice except that it makes me think of roast lamb). This turned up huge numbers of Entomobrya multifasciata, but also some other interesting species, Katiannidae genus nov.1 sp. nov.:



and Katiannidae genus nov.1 sp. nov.2:




I then moved on to the clump of Ivy that had yielded the lone female Entomobrya nigrocincta. Once again I found large numbers of Entomobrya intermedia, but this time also a few Entomobrya multifasciata (which was a bit worrying). There were some more Katiannidae genus nov. but the most striking finds here were a number of Jordanathrix nr superba and quite a lot of the biggest Dicyrtomina saundersi I have ever seen - huge beasts!




I will be making future visits to the Garden to keep looking for Entomobrya nigrocincta and to study the Katiannidae genus nov. further.