(037/WLden) Willemia denisi (Mills, 1932)
*aspinata Stach, 1949
Records to date for Willemia denisi have all been under the name Willemia aspinata which was shown by Fjellberg (1985) to be a junior synonym. Willemia denisi is the only species of Willemia found in Britain and Ireland which does not possess two anal spines. The post-antennal organ (PAO) is relatively large with (usually) four lobes (Fig. 1). The foot possesses a small empodium (Fig. 2) and the fourth antennal segment (ant4) bears a number of teardrop-shaped sensillae (Fig. 3).
Figure 1: Four-lobed (1-4) post-antennal organ (PAO) of Willemia denisi collected from Arne Big Wood, Dorset in November 1963 by Peter Lawrence.
Figure 2: Foot of third leg (leg3) of Willemia denisi collected from Lightwater, Surrey in May 1951 (collector unknown). The empodium (e) is about 0.4 times as long as the claw.
Figure 3: Tip of antenna of the same specimen of Willemia denisi shown in Fig. 1. The fourth antennal segment (ant4) bears several teardrop-shaped sensillae, only one of which (s) is in the plane of focus of the photograph.