Phthiracarus flexisetosus, 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 : 339-341

Phthiracarus flexisetosus sp. nov.

(Fig. 7D-F)

Adult: Medium-sized and moderately strongly sclerotized. The aspis (Fig.7D) ranges in length from 230-255 µm with a greatest width of 170-220 µm. All the dorsal setae are fine and rather long. Setae (il) are about 1-5 times the length of setae (la) and equal to the distance il-ro. The rostrals, which are inserted relatively far apart, do not reach the anterior limit of the aspis. The sensillus (Fig. 7E) is 30 - 40 µm long, broadly clavate, serrated and closely resembles that found in P. clavatus . The notogaster (Fig. 7F), about 560 µm long and with a greatest depth of about 330 µm, is elongate in lateral aspect. All the setae are long (more than the distance c1 - d1), fine and slightly flexuose. Setae c1 and c3 are inserted on the posterior margin of the collar and seta a submarginally. Vestigial f1 is located adjacent to seta h1 and towards the mid-dorsal line. The fissures ip and ips are absent. On each anal plate there are only three setae, of which ad3, is rather short. The chelicerae are about 172 µm long. The principal segment carries 16-19 sharply pointed spines on the paraxial surface and 12- 17 conical spines antiaxially. The leg chaetotaxy is of the 'reduced type' with the setal formulae: I (1-3-2-5-15-1); II (1 —3—2—3—11— 1); III (2-2-1-2-10-1) and IV (2-1-0-2-9-1). On tarsus I seta u' is short, thick and resembles a eupathidium.

Types: Holotype, BMNH reg. no. 1976.2.18.17, and two paratypes, 1976.2.18.18-19, from the F layer under a mixed stand of beech and oak, New Forest, Hampshire, 27.iii.73 (B. W. Parry). P. flexisetosus is known only from the type locality.

Remarks: In comparison with the other 'reduced chaetotaxy' species examined, P.flexisetosus is rather large and the interlamellar and notogastral setae are much longer.