Phthiracarus nitens (Nicolet)

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 : 346-348

Phthiracarus nitens (Nicolet)

(Fig. 12A-C)

Hoplophora nitens Nicolet , 1855: 472.

Phthiracarus nitens : van der Hammen, 1964: 400 (neotype designated).

Adult: Large and moderately sclerotized. The aspis (Fig. 12B) ranges in length from 253 - 460 µm with a greatest width of 213 - 360 µm. All the dorsal setae are fine and short. Setae (il) are about 1-5 times the length of setae (la) and extend two-thirds of the distance il-ro. The sensillus (Fig. 12A) is 50-60 µm in length, narrow and resembles that of P. laevigatus . The notogaster (Fig. 12C) ranges in length from 502 - 900 µm with a greatest depth of 299 - 600 µm. All the setae are short (less than the distance c1 - d1), fine and procurved. Seta c3 is inserted on the posterior margin of the collar and setae c1-2 submarginally. Vestigial f1 is located midway between setae h1 and ps1. The fissures ip and ips are present. On each anal plate there are only three setae; an1_2 being much longer than ady. The chelicerae are approximately 270 µm long. The principal segment carries 17-21 sharply pointed spines on the paraxial surface and 10-19 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 II seta ft" is hooked distally.

Distribution: P. nitens was collected in small numbers from the following localities: Wytham Woods Estate, Berkshire, 28.x.70 (T. G. Wood); St Agnes, Isles of Scilly, Cornwall, 5.iv.57 (K. H. Hyatt); Higher Kiln Quarry, Devon, 25.iv.64 (C. Moreby); Tring Deer Park, Hertford- shire, l.ii.64 (P. N. Lawrence).

Remarks: The neotype from Regensburg has been examined and in comparison with the British material the notogastral setae appear to be somewhat longer. The leg chaetotaxy is of the 'complete type'. On tarsus I the solenidion omega2 is coupled with a short distal seta and on tarus II the posterior fastigial seta is hooked distally. Neither of these features was noted by van der Hammen in his redescription.

P. nitens is similar to if not conspecific with P. montanus recorded by Perez-Inigo in grassland soil and moist moss, Sierra de Guadarrama, Spain. The holotype was examined and seen to be cleared but undissected. In comparison with P. nitens , it differs only in the form of the distal region of the sensillus which is lobular in montanus and pointed in nitens .