http://www.collembola.org/publicat/theblob.htm
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Last updated on
1999.12.29
by Frans Janssens
Frans Janssens,
Department of Biology, University of Antwerp (RUCA), Antwerp, B-2020, Belgium
Dan L. Johnson,
Agriculture and Agri-Food Canada Research Centre, P.O. Box 3000, Lethbrigde, Alberta, Canada
Preamble
Note: This preliminary version of the document is .
Results can change and conclusions can be rethought. It is recommended to not
copy down, print or quote this text. To keep up to date, it is preferable to
use a hyperlink in steadt.
This manuscript is a compilation of the cooperative communication between
Dr Dan L. Johnson of the Agriculture and Agri-Food Canada Research Centre
of Lethbridge, Canada and myself on the sudden appearance of small
aggregations of a Hypogastrurid springtail in Lethbridge, Canada.
History
- 1997,06.05. Dr Dan L. Johnson of the Agriculture and Agri-Food
Canada Research Centre of Lethbridge, Canada
asked me to confirm his tentative determination of
'Ceratophysella pseudarmata' from high density aggregations in Lethbridge, Canada.
- 1997.06.06. Dr Johnson shipped a vial with some hypogastrurid specimens to be determined.
- 1997.07.01. Dr Johnson shipped a second vial with some hypogastrurid specimens to be determined.
- 1997.07.09. The first vial with specimens arrived. Preliminary identification : not Ceratophysella.
- 1997.07.11. Tentative identification : Hypogastrura cf. vernalis (Carl, 1901).
- 1997.07.15. Final identification : Hypogastrura ripperi Gisin, 1952.
- 1997.08.01. The second vial with specimens arrived.
- 1997.08.11. Photographs made of lateral and dorsal habitus.
- 1997.10.20. Detailled description of habitat.
- 1998.03.16. Photographs made of anal spines and mucro.
Material
The specimens have been collected by Dr Dan L. Johnson in small numbers from
May 19 to May 27, 1997 when they appeared in small masses, and since those
dates they could be found easely in less aggregated densities by leaving a
pan of water out overnight.
Habitat
Masses were actually irregular films on the surface of wet straw at one site,
dead grasscuttings at another site. The most were found at an outdoor dog
kennel on the surface of wet straw mixed with small amounts of urine and food.
Material
Vial 1 : 68 Collembola specimens in ethanol
Vial 2 : .. Collembola specimens in ethanol
Note : they were not 'fixed' : the transparant cuticula
came loose from the body, as if each specimen was wrapped
into a transparant plastic bag. Gisin's fixative 1
could have prevented this artefact.
Label :
Vial 1 :
Mar 26, 1997
Lethbridge, AB, Canada
Dan Johnson
Hypogastruridae
Ceratophysella pseudarmata ?
Vial 2 :
Suspected Ceratophysella pseudarmata
D. Johnson, col
Mar 27-30, 1997
Lethbridge, Alberta, Canada
Preliminary observations
After one hour in Gisin's clearing medium 2 and using a stereo microscope
at low magnification, the following observations could be made :
- general habitus :
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Fig.1. Habitus lateral 40x Photograph Frans Janssens copyright © (1997) |
Fig.2. Habitus dorsal 32x Photograph Frans Janssens copyright © (1997) |
- body length maximum 1.2 mm.
- colour dorsally black-bluish to brown-reddish, white spotted; most
specimens with typical 2 dorso-lateral white spotted lines
from thorax II to abdomen V;
colour ventrally more pale.
- black eye patches.
- the 4th antennal segment seemingly fused with the 3rd.
- no anal spines visible.
Based on Christiansen & Bellinger (1980),
Ceratophysella cannot be confirmed : 'Nearctic Ceratophysella should
have relatively large (never minute) anal spines'.
Also Folsom's original description (1916) of
Achorutes pseudarmatus specifies 'anal spines long'.
These preliminary observations indicate that it is not a Ceratophysella species.
Tentative identification
With a compound microscope at 100x,
on the distal part of the anal segment (abdomen VI),
two minute anal spines on papillae are clearly visible.
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Fig.3. Anal spine 100x Photograph Frans Janssens copyright © (1998) |
The key of the Norwegian Collembola of Fjellberg (1980)
leads straightforward to Hypogastrura vernalis :
Poduridae
- Furca not reaching second pair of legs when folded forwards.
- Mandibles with strong molar plate, easily seen in cleared specimens.
- Furca well developed, dens at least with 3 setae.
- Head with 8+8 eyes, dark species ==> Hypogastrura
Hypogastrura
- Empodium of normal size.
- Mucro usually long and slender. Tibiotarsi with one ore more knobbed
tenent hairs. No protrusible sac on antennae. Body hairs
usually short, anal spines short ==> Hypogastrura sensu stricto
- Tibiotarsi with only 1 knobbed tenent hair.
- Posterior side dens with distinct papillae, largest apically.
- Empodium with a small lamella.
- Mucro shorter [then manubrialis],
with distinct tooth before apex ==> vernalis (Carl, 1901)
Empodium with small, narrow lamella.
Mucro with distinct tooth before apex.
1.2 mm. Dark bluish red. Anal spines short, stright. Often
in large numbers in dry meadows close to sea.
Stach (1949) states about Neogastrura manubrialis :
'the limit between those segments [3rd and 4th antennal
segments] sometimes indistinct'. What is certainly the case for this set of specimens.
In fact, it is more or less valid for all
Hypogastrura s.s. Also the fact that the antenna
is thickest at the joint of the 3rd and 4th segment
gives the impression (at lower magnification) that
the 4th segment is fused with the 3rd.
Stach (1949) notes on N. purpurescens dorso-lateral
spotted lines. Those are clearly seen also in these specimens.
Tentative identification : Hypogastrura cf. vernalis (Carl, 1901)
Note that all characters apply to the blob specimens except that the specimens
do not have knobbed tenent hairs... Therefore, the use of 'cf.'
Final identification
The acuminate tenent hair, together with the
statement of Christiansen & Bellinger (1980) that there are 'no valid Nearctic
records for Hypogastrura vernalis', and the fact that Hypogastrura vernalis is not
listed in the checklist of Skidmore (1995) motivates a reidentification,
this time based on the key of Gisin (1960).
After verifying Gisin's diagnosis of H.(H.) vernalis against some
completely cleared specimens (gently heated on electrical heating plate in
Gisin's clearing medium), the tentative identification has to be revised.
Following the key of the European Collembola of Gisin (1960) :
Hypogastrura (Hypogastrura)
- Alle Tibiotarsen met je höchstens 1 Keulenhaar.
- Dens mit 6-7 Borsten.
- Anal Dornen auf niedrigeren [then papillata] Papillen.
- Hautkörner auf der Hinterseite der Dentes gegen den Mucro hin stark an
Grösse zunehmend, manchmaal zu Dornen vergrössert.
- Empodium nur mit kleiner Lamelle.
- [Rücken]Borsten glatt oder höchstens schwach rauh.
- Mucrospitze gerade oder mehr oder weniger hakenförmig.
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Fig.4. Mucro with broad lamella 100x Photograph Frans Janssens copyright © (1998) |
- Mucro mehr oder weniger hakenförmig, kürzer, mit breitere Lamelle.
Ant. I mit zusätzlicher Borste vor dem Borstenquirl.
- Tibiotarsus mit spitzem Spürhaar. Im PAO sind die beiden vorderen
Höcker grösser als die hinteren und quer gestellt.
==> ripperi Gisin, 1952
- 1.5 mm. Grau-blau. Abd. V und VI dorsomedian mit stärkerer
Hautkörnung. Ant. IV mit 3-4 äusseren und 2-3 inneren Riechhaaren.
Klaue mit Innen-, ohne Seitenzahn. Tibiotarsus ohne Keulenhaar.
Ventraaltubus mit 4+4 Borsten (unveröff.). Tenaculum mit 4+4
Zähnen.
This identification is confirmed using the key of the Nearctic Collembola of
Christiansen & Bellinger (1980).
Both publications mention Neogastrura assimilis Stach 1949, nec Krausbauer 1898
as synomym of ripperi. Stach (1949) has a very detailed diagnosis of
Neogastrura assimilis.
Final identification : Hypogastrura (Hypogastrura) ripperi Gisin, 1952
Location : | Lethbridge, Albertha, Canada |
Date : | 1997.03.26-30 |
Leg. : | Dr Dan L. Johnson |
Det. : | Frans Janssens |
Col. : | Dr Dan L. Johnson |
Photographs of cleared specimens were made with a Fuji dia positive film
of 100 ASA, type day-light.
Dr De Bruyn of the RUCA, Antwerp, Belgium was so kind to provide for the scanned
JPEG images.
At least the following photographs are to be made to document the identification :
- mandible 600x (to show molar plate and four apical teeth)
- eye patch with post antennal organ (and if possible first antennal segment) 600x
(to show : eye and PAO infrastructure, and chaetotaxy of ant.I)
- 'fused' antennal segments III and IV 100x
- tarsus III 600x (to show the acuminate tenent hair and empodium)
References
Endnotes
1 Gisin's fixative :
95% ethanol | 750 ml |
ethyl ether | 250 ml |
glacial acetic acid | 30 ml |
40% formaldehyde | 3 ml |
2 Gisin's clearing medium :
lactic acid | 100 ml |
glycerol | 20 ml |
40% formaldehyde | 4 ml |