ISLE OF WIGHT DISEASE IN' HIVE BEES — ACARlNE DISEASE. 
F69 
pure nelle femmine, normali, conformate come quelle del secondo e terzo pajo, 
colla differenza che hanno un’ ungliia sola. Zampe del quarto pajo nel maschio 
robuste, constituent! insieme unachela, terminate da un’ unghia robusta. Epimeri 
del terzo e quarto pajo nel maschio assai lunghi e forti e convergent insieme 
verso l’avanti. Scudo dorsale diviso in segment. Animali viventi su piante.” 
The adult female of the species to be described conforms well to the generic 
characters given above, and cannot, in my opinion, be separated from the genus 
Tarsonemus. The only morphological character upon which such a separation 
could be . based is the conformation of the fourth pair of legs, and possibly the 
absence of pseudostigmata (not included in the original generic description). The 
male is undoubtedly more specialised in the fourth leg characters, but to con- 
stitute a new genus upon this fact, or upon the parasitic habit with which this 
specialised feature appears associated, seems to me inadmissible, at any rate in 
the present state of our knowledge. 
A distinctive feature of the genus Tarsonemus is the fourth pair of legs, 
which in the female are slender, terminate in two hairs, and are devoid of 
claws. In the male, in the gall-inhabiting and free-living species, the last pair 
of legs is robust and terminates in a claw-like segment, usually incurved and 
frequently strongly developed. In some of the species recorded as endoparasitic, 
these characters in the male appear less well marked, and in the main show a 
reduction* in size of this pair of appendages. In the species to be described the 
hind legs in both sexes present, especially in the male, features which I regard 
as related to the parasitic mode of life and restricted habitat of the insect’s 
tracheal system. 
Tarsonemus woodi, n. sp. 
I propose to designate this species, which is parasitic in the anterior thoracic 
tracheal system of the hive bee, Apis mellijica , and which does not appear to 
have been described before, by the name of Tarsonemus woodi, n. sp. The adult 
ovigerous female measures from ’14 to T9 mm. in length, the male about ’ll to 
T5 mm. (fig. 1). Viewed with reflected light, these mites are more or less bean- 
shaped in form, greyish in colour, and scantily bedecked with hairs. When removed 
from the tracheae of the bee they progress slowly upon glass, but when seen within 
the tube, although continued observation has not revealed much progression, a good 
deal of active and vigorous leg movement may be observed. 
Ovigerotjs Female. — Seen from above, the body presents a somewhat oval 
form, broadest in the neighbourhood of the second pair of legs. The following are 
typical dimensions for a fully grown adult : — 
Total length from tip of gnathosoma to hinder end of body, T9 mm. 
Total length from tip of gnathosoma to tip of longest hair of fourth pair 
of legs, ’25 mm. 
TRANS. ROY. SOC. EDIN., VOL. LII, PART IV (NO. 29). 
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