Unlike sabellid fan worms, which often have well-developed segmental and pygidial
ocelli (Ermak and Eakin, 1976; Dragesco-Kerneis, 1980), serpulid fan worms appear to be largely devoid of superficially obvious ocelli or eyes posterior to the collar.
melanocephalum workers effectively utilize their pygidial
gland secretions as an alarm-defense system during aggressive encounters with other invaders (Tomalski et al.
A comparatively narrow, three-dimensionally preserved tube-like relic is visible inside the thoracic and pygidial
Harper, "An Early Cambrian Stem Polychaete with Pygidial
Cirri," Biology Letters 7 (2011): 929-32.
shield present, its margin undulate and bearing one pair of smooth and needle-like setae (ca 50-60 [micro]m), surface of this plate covered by oval pits.
Hosts for these species are unknown, but each species had a well-defined pygidial
We found that the major constituent in the pygidial
gland defensive fluid of the ground beetle Ardistomis schaumii is (r)-(+)-limonene, whereas that of closely related species Semiardistomis puncticollis is (S)-(-)-limonene," he said.
plate broad and subtruncate, its lateral carina not rounded (Tsuneki, 1983a: 73-77).
1a); base of metepisternum, apex of metacoxa and lateral areas of ventral segments 2 to 5 with dense white hairs; legs with sparse white hairs; undersurfaces with moderately dense white to golden pubescence; pygidial
pubescence varying from uniform, moderately dense white hairs to white or brown hairs with a dense median stripe of white hairs.
Dorsal and pygidial
dressing velvety or setiferous.
These arachnids are well known for their ability to spray defensive, vinegar-like secretions from their pygidial
glands (Schmidt et al.
The Bohemian Actinopeltis Hawle & Corda, 1847 has rather short pygidial
spines similar to those of Reraspis, but the number of thoracic segments is smaller whereas the number of pygidial
segments is higher.