Phthiracarus rectisetosus, Parry, B. W., 1979

Parry, B. W., 1979, A revision of the British species of the genus Phthiracarus Perty 1841 (Cryptostigmata: Euptyctima), Bull. British Mus. nat. Hist., Zool. ser. 35, pp. 323-363 : 348

Phthiracarus rectisetosus sp. nov.

(Fig. 12D-F; Pl. 5c)

Adult (Pl. 5c): Large and strongly sclerotized. The aspis (Fig. 12D) ranges in length from 350 - 477 µm with a greatest width of 268 - 360 µm. All the dorsal setae are fine and short. Setae (il) which are inserted rather far forward and on a level with setae (la) are about 1-5 times the length of the latter and extend two-thirds of the distance il-ro. Setae (ro) do not reach the anterior limit of the aspis. The sensillus (Fig. 12E) is 40 µm long, ovate, serrated distally and resembles that found in P. murphyi . The notogaster (Fig. 12F) ranges in length from 710 - 994 µm with a greatest depth of 482 - 720 µm. All the setae are relatively long (equal to the distance c1 - d1) and almost erect. Setae c1 and c3 are situated on the posterior margin of the collar and seta c2 submarginally. Vestigial fis located a short distance posterior to seta h1. The fissures ip and ips are present. On each anal plate there are five long setae; an1-2 and ad1 being more or less equal in length and somewhat shorter than ad1_2 The chelicerae are 168-294 µm long. The principal segment carries 22 - 24 sharply pointed spines on the paraxial surface and 17 - 22 conical spines antiaxially. The leg chaetotaxy is of the 'complete type' with the setal formulae: I (1-4-2-5-16-1); II (1-3-2-3-12-1); III (2-2-1-2-10-1) and IV (2-1-1-2-10-1). On tarsus I the distal seta coupled with solenidion omega2 is almost as long as the famulus. Seta ft" on tarsus II is hooked distally.

Types: HOLOTYPE, BMNH reg. no. 1976.2.18.8, and one paratype, 1976.2.18.9, from beech litter, Burnham Beeches, Buckinghamshire, 1964 (G. O. Evans). Two paratypes, 1976.2.18.10-11, from beech F, Wytham Woods Estate, Berkshire, 28.ix.70 (T. G. Wood).

Distribution: Common in mor soils particularly under beech. P. rectisetosus is evidently widely distributed in the British Isles and was abundant in all the samples examined from Monks Wood, Cambridgeshire, 16.V.75 (J. A. Moffat); Woodbastwick Marshes, Norfolk, 10.vii.74 (S. J. Moore); West Allendale, Northumberland, 18.ix.75 (R. M. Emberson); Long Compton Woods, Warwickshire, 15.viii.51 (P. N. Lawrence); Hag Wood, Yorkshire, 12.iv.71 (D. R. Kime); Newtonmore, Inverness-shire, 3.vii.73 (M. J. Bishop); Lochdonhead and Tobermory, Mull, 28.V.70 (P. N. Lawrence); Torboll, Sutherland, 29.vi.76 (P. D. Hillyard); Llanthony, Monmouth- shire, i.iv.73 (M. J. Bishop).

Remarks: P. rectisetosus bears some resemblance to two other 'complete chaetotaxy' species, namely P. clavatus and P. globus . However, P. rectisetosus bears four pairs of lateral fissures while P. clavatus and P. globus bear only two pairs.