(030/SCemu) Schaefferia emucronata 'group' (Absolon, 1900)

The reason for placing all UK/Eire specimens of Schaefferia into a single group, the Schaefferia emucronata 'group' is the lack of stability of the characters used to separate the 'species'. The Schaefferia Steven has seen (some 60 specimens), mostly from caves but some from soil and humus outside caves, have 3+3, 3+4 or 4+4 ocelli (Fig. 1-3) (a specimen labelled Schaefferia sexoculata in the NHML collection has 4+4 ocelli!). All specimens have large anal spines (Fig. 4) and the empodium of the foot has a distinct lamella (Fig. 5). The mucro is absent from some specimens and present in others (Fig. 6, 7), but is occasionally present on one dens but not the other in the same specimen (Fig. 8). The most sensible course would seem to be to use the earliest name Schaefferia emucronata Absolon, 1900 even though calling a specimen with a mucro 'emucronata' is an odd thing to do.  The same cave (Red rake mine) turned up 3 eyed Schaefferias in 1965 (det. peter Lawrence) and 2002 (det. Peter Shaw), suggesting that this might be a stable feature in that isolated population.

Specimens from UK/Eire included in this group are Schaefferia emucronata, Schaefferia lindbergi, Schaefferia pouadensis, Schaefferia sexoculata and Schaefferia willemi (and its synonyms cavernicola, longispina and octoculata). The publication of Thibaud et al. (2004) gives species status to Schaefferia emucronata, Schaefferia lindbergi, Schaefferia pouadensis, Schaefferia sexoculata and Schaefferia willemi. However in UK/Eire specimens, there is so much variation between individuals within populations of Schaefferia from the same localities that it is impossible to reliably use their key to separate the taxa. Further work is required on inter-and intra-specific variation in UK/Eire material to determine the species boundaries.

 

 

 

Map Schaefferia emucronata 'group'

Map of Schaefferia emucronata s.lat., uploaded 16July2014

Post-antennal organ and three adjacent ocelli of Schaefferia emucronata

Figure 1: Four-lobed (1,2,3,4) Post-antennal organ (PAO) and three adjacent ocelli (*) of Schaefferia emucronata 'group' collected from Dan-Yr-Oguf cave in May 1966 by the Cave Research Group.

Post-antennal organ and three adjacent ocelli of Schaefferia emucronata

Figure 2: Post-antennal organ (PAO) and three adjacent ocelli (*) of Schaefferia emucronata 'group' collected from a cave in Devon by W. Maxwell (exact locality and date not known).

Post-antennal organ and three adjacent ocelli of Schaefferia emucronata

Figure 3: The opposite side of the same specimen shown in Fig. 2. Note that there are four ocelli (*) adjacent to the PAO.

Prominent anal spines of Schaefferia emucronata 'group'

Figure 4: Prominent anal spines of Schaefferia emucronata 'group' collected from Sandford Levvy, Somerset in August 1966 by the Cave Research Group.

Foot of leg3 of Schaefferia emucronata 'group'

Figure 4: Foot of leg3 of the same specimen shown in Fig. 4 at the same magnification. The empodium (emp) has a basal lamella.

Lateral view of the furca of Schaefferia emucronata

Figure 6: Lateral view of the furca of Schaefferia emucronata 'group' collected from Box Mines, Wiltshire in January 1969 by R. Pearce.

Ventral view of the furca of Schaefferia emucronata 'group'

Figure 7: Ventral view of the furca of Schaefferia emucronata 'group' collected from Swildon's Hole, Somerset in April 1968 by the Cave Research Group.

Ventral view of the furca of a specimen of the Schaefferia emucronata 'group'

Figure 8: Ventral view of the furca of a specimen of the Schaefferia emucronata 'group' collected from Blakes Farm Swallet, Somerset by the Cave Research Group (date not known). The dens on the right bears a mucro but the mucro is absent from the dens on the left.

 
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