labium


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labium

1. a lip or liplike structure
2. any one of the four lip-shaped folds of the female vulva
3. the fused pair of appendages forming the lower lip of insects
4. the lower lip of the corolla of labiate flowers
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

labium

[′lā·bē·əm]
(biology)
A liplike structure.
The lower lip, as of a labiate corolla or of an insect.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Abbreviations: an, antenna; ce, compound eye; cl, clypeus; lb, labium; ls, labial sensilla; se, setae; sf, salivary flange; so, stylet-holding organ; st, stylets, wf waxy filaments (secreted by the melaleuca psyllid).
citri nymph, showing the extended tip of the stylets (st) and the partially retracted/looped part of the stylets (rs): cg, clypeal groove, cl, clypeus; lb, labium; lb1 & lb2, labial segments 1 & 2; rs, retracted/looped stylets; so, stylet-holding organ.
The main external morphological characters indicating the types of sensilla are pores system (visible or not), the manner in which the sensilla are sunken with respect to the surface of the labium (flexible or inflexible sockets), and the shape of the sensilla.
The chaetic sensilla are present in all examined species in various parts of the labium.
This genus is most closely related to Riazocoris in having labium reaching at least to metacoxae, sometimes passing much beyond to third abdominal segment and second antennal segment equal, subequal, or slightly shorter than third but it can easily be separated from the same in having labium passing much beyond metacoxae, reaching to third abdominal sternum, apical margin of scutellum distinctly round, not subacute and clypeus distinctly longer than paraclypei, dorsally raised.
Distinctly broader than its length, anteocular distance slightly shorter than remainder of head, paraclypei shorter than clypeus, latter dorsally raised, lateral margins slightly sinuate and anteriorly rounded with convex margin, paraclypeal lobe just above the eyes rounded; antennae with basal segment shorter than haed apex, length of antennal segments I 0.5, II 0.9, III 0.9, IV 1.4, V 1.7, antennal formula 1 less than 2=3 less than 4 less than 5; labium passing much beyond hind coxae reaching to 3rd abdominal venter, length of labial segments I 0.8, II 1.4, III 1.3, IV 0.9; labial formula, 1 less than 4 less than 3 less than 2; length of anteocular region 0.8; posterior of head including eyes 0.9; width of head 2.6.
One labium was removed entirely, and nerve damage resulted in loss of sensation and painful intercourse.
The latter differ considerably from the remaining nepomorpha families: the labium of the corixids is shorter and broader, without a distinct fourt-part segmentation [20-23], (Brozek, submitted, 2013).
In most Nepomorpha as well as in most other heteropterans (e.g., Leptopodomorpha, Gerromorpha, and Pentatomomorpha), the labium is typically four-segmented [4, 9, 18, 20].
Labium light brown, lighter at anterior margin, darker laterally at base; 0.40 long, 0.34 wide.