(393 SNele) Sminthurinus elegans (Fitch, 1863)

*quadrilineatus (Tullberg, 1871) [in part]
*signatus Krausbauer, 1902

Sminthurinus species are very variable in colour pattern and it is essential to examine the presence or absence of ventral subapical setae on the dens in order to make a correct identification.  A useful (and much easier) character is to examine whether the 'small abdomen' (the animal's "tail end") is visibly sub-segmented or not.  The Sminthurinus aureus group has this body portion wholly fused, while other UK Sminthurinus have a visible divison between segments 5 and 6.  (This suggests a useful change that could be made to the AIDGAP Collembola key at tupple 257: I suggest an improved wording below).

The Sminthurinus 'aureus -group' includes species of Sminthurinus without ventral subapical setae on the dens and an undivided small abdomen. According to Bretfeld (1999), specimens without clear patterning on the abdomen should be recorded under the name Sminthurinus aureus, with different names for different colour patterns on the abdomen. However, it is possible that all these 'species' are simply colour varieties of one taxon that should be called Sminthurinus aureus. The AIDGAP key by Steve Hopkin keys out Sminthurinus elegans (four longitudinal bands), Sminthurinus signatus (two longitudinal bands) and Sminthurinus bimaculatus (pronounced white spot on either side of the abdomen).  Since then Keith Brocklehurst and Edward Nurcombe have separately added Sminthurinus reticulatus, which has cross-banding on its abdomen.   Paul Ardron has photographed a sminthurid in the lost gardens of Heligan that appears to be the "dorsalis" colour pattern of this species (Fig. 5), while Keith Brocklehrst and Edward Nurcombe have  found "reticulatus" (Fig. 7).  This entire group needs a DNA-based taxonomic revision!  These are among a surprising number of unfamiliar sminthurids that have appeared in UK gardens and ornamental settings since 2000 (see also Katianna schoetti).

Sminthurinus elegans as keyed out in the AIDGAP key is very common and widespread, found in leaf litter and low vegetation in almost all terrestrial habitats, preferring drier areas than aureus. It reaches 1.0 mm in length and is and is yellowish in colour with four bluish black longitudinal bands. The fourth antennal segment (ant4) is NOT subdivided (Fig. 1). The outer margin of the mucro is smooth and the inner margin is serrated (Fig. 1). Ventral sub apical setae are NOT present on the dens (Fig. 2).  In females  the long setae surrounding the anus are expanded at the base (Fig. 3), and the sub-anal appendages (SAA) are feathery at the tip (Fig. 4) . . The empodium of legs 2 and 3 is slightly shorter than the claw, but is slightly longer than the claw on leg1.

 

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Suggested change to the 2007 AIDGAPCollembola key:

p. 179 tupple 252

Existing Text

“Dens with one or two subapical ventral setae …………….253

Dens without subapical ventral setae………………Sminthurinus aureus group .258”

 

Change to:

“Dens with one or two subapical ventral setae, abd V demarcated from Abd VI (eg fig 107)  ………..……….253

Dens without subapical ventral setae, abd V used to Abd VI (eg fig 108) ………………Sminthurinus aureus group .258”

 

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Distribution map for Sminthurinus elegans

 

 

 

Fig. 1 and 2: Mucro and distal dens at two levels of focus of Sminthurinus elegans collected from Kew Gardens in September 1961 by J.L. Gilbert. Note (In Fig. 2) that ventral subapical setae are ABSENT (*) from the dens.

 

 

 

 

 

 

 

Fig. 3: Sixth abdominal segment (abd6) of the same specimen of Sminthurinus elegans shown in Fig. 1. Note that the setae surrounding the anus are expanded at the base. The region including the sub-anal appendages (SAA) is shown at higher magnification in Fig. 4.

 

 

Fig. 4: Female Sub Anal Appendages (SAA) of the same specimen of Sminthurinus elegans shown in Fig. 3. Note that the tips of the SAAs are feathery.

Fig 5: Sminthurinus elegans var dorsalis, photographed by Paul Ardron in Heligan botanic gardens, 2009.

Fig. 6: Sminthurinus elegans, from Barking woods Essex 1997, col P. Shaw

Fig. 7: Sminthurinus forma reticulatus, photographed by Edward Nurcombe near melton Mowbury March 2012.

 
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