Phthiracarus ferrugineus (C. L. Koch)

Kamill, B. W., 1981, The Phthiracarus species of C. L. Koch, Bulletin of the British Museum of Natural History (Zoology series) 41, pp. 263-274 : 266-268

Phthiracarus ferrugineus (C. L. Koch)

(Figs 9-13)

Hoplophora ferruginea Koch , 1841: Heft. 32, t. 10. Regensburg [type series presumed lost]. NEOTYPE (here designated), Taimering, Regensburg (RNH, Leiden, P2005-7). [ Phthiracarus ferrugineus : Jacot, 1936: 179. Misidentification, see under P. longulus .]

Adult: Rather small and weakly sclerotized. The aspis (Figs 10-12) is about 225 µm in length with a greatest width of about 160 µm. The rostrals (ro) are short and do not reach het anterior aspal margin. Setae (il) are twice the length of setae (la) and extend to the rostral bases. The sensilli are long (70-80 µm), slender and distally serrated. The exobothridial setae (ex) are short. The notogaster (Fig. 9), about 350 µm in length, has a maximum depth of about 270 µm and bears moderately long (more or less equal to the distance c1-d1), simple setae which are erect to recurved. Setae c1 and c3 are inserted close to the posterior co? margin and seta c2 submarginally. Vestigial f1 is located one-third of the distance between setae h1 and ps1. Only the fissures ia and im appear to be present. On each anal plate there are three setae (setae ad1-2 vestigial) of which an1-2 are the longest. The chelicerae are 135-140 µm long with 9 to 10 sharply pointed spines on the paraxial surface of the principal segment and 6 to 10 conical spines antiaxially. The leg chaetotaxy is of the 'complete type' with rather short and straight solenidia. On femur I (Fig. 13) seta d is short (about half as long as l'), thickened and, as in crinitus , this seta is curved and bluntly serrated. In the three available specimens, the setal arrangement on this segment shows considerable variation of the neotype (Fig. 13) seta d is located on a level with seta l' and anterior to the ventral seta, while in a second specimen d is located anterior to the lateral seta, and in a third specimen posterior to the lateral seta.

Material: Three specimens from rotten material in a moist hayfield, Taimering, Regensburg, 19.vi. 1961 (L. van der Hammen) (sample no. 61 R34), deposited in the collection of the Rijksmuseum van Natuurlijke Historie, Leiden. One of these specimens (P2005-7) hereby designated as the neotype.

Remarks: Koch recorded ferruginea in mosses on trees. He described the species as being very small with long, fine notogastral setae and from his figure it is evident that the species possessed rather long and prominent sensilli.

The smallest of the Regensburg species examined in the present study, P. ferrugineus (notogastral length 350 µm) is somewhat unusual in its possession of four setae on femur I and a single seta on genu IV, two features which are associated with larger species (notogastral length 500-1000 µm) of the genus. Smaller species with a notogastral length of less than 500 µm are generally characterized by a 'reduced' form of leg chaetotaxy.

Although rather smaller, P. ferrugineus bears considerable resemblance to P. membranifer Parry (notogastral length 310-500 µm) recorded from the fermentation layer under Sitka spruce, Tintern Forest, Monmouthshire. In comparison with the latter, P. ferrugineus differs only in having a 'complete' form of leg chaetotaxy.