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n. pl. py·gid·i·a (-ē-ə)
The posterior body region or segment of certain invertebrates.

[New Latin, from Greek pugidion, diminutive of pugē, buttocks.]

py·gid′i·al (-ē-əl) adj.


(paɪˈdʒɪdɪəm; -ˈɡɪd-)
n, pl -ia (-ɪə)
(Zoology) the terminal segment, division, or other structure in certain annelids, arthropods, and other invertebrates
[C19: from New Latin, from Greek pugē rump]
pyˈgidial adj


(paɪˈdʒɪd i əm)

n., pl. -gid•i•a (-ˈdʒɪd i ə)
any of various structures or regions at the caudal end of the body in certain invertebrates.
[1840–50; < Greek pȳg(ḗ) rump + -idium]
py•gid′i•al, adj.
References in periodicals archive ?
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.
Harper, "An Early Cambrian Stem Polychaete with Pygidial Cirri," Biology Letters 7 (2011): 929-32.
Pygidial 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 plate.
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.
Pygidial 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.
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.