α. 1800s epistom, 1800s– epistome.
β. 1800s– epistoma.
epistomen.
/ˈɛpᵻstəʊm/, U.S. /ˈɛpəˌstoʊm/ Zoology.
In various invertebrates, esp. arthropods: a plate, process, or other structure lying above or in front of the mouth; (also) the region of the head above or in front of the mouth. Cf. clypeus n.
ΘΚΠ
the world > animals > invertebrates > phylum Arthropoda > [noun] > member of > parts of > mouth-like appendage > organs surrounding mouth
epistome1826
mouthpart1867
1826 Zool. Jrnl. 2 431 Labrum and mandibles entirely hidden during repose by the anterior extremity of the sternum, prothorax, epistome or clypeus then applied over it, enlarged and transverse in front.
1833 E. Griffith et al. Cuvier's Animal Kingdom XIII. 163 The epistoma, or interval comprised between the antennæ and the buccal cavity, is almost always square, as long, or almost as long, as broad.
1852 J. D. Dana U.S. Exploring Exped.: Crustacea Pt. I 25 The base of the antennæ is thus cut off from the rest of the epistome.
1878 F. J. Bell & E. R. Lankester tr. C. Gegenbaur Elements Compar. Anat. 160 The mouth..is in one division overhung by a movable process—the epistom [Ger. Epistom].
1880 T. H. Huxley Crayfish 155 In front of the mouth, the sternal region which appertains, in part, to the antennæ, and, in part, to the mandibles, is obvious as a broad plate..termed the epistoma.
1897 T. J. Parker & W. A. Haswell Text-bk. Zool. I. 499 The head exhibits no segmentation: its sternal region is formed largely by a shield-shaped plate, the epistoma, nearly vertical in position.
1909 Cambr. Nat. Hist. IV. 291 In Pterygotus there is a well-developed epistome..between the mouth and the front margin of the carapace.
1957 O. W. Richards & R. G. Davies Imms's Gen. Textbk. Entomol. (ed. 9) iii. 752 Among Curculionoidea the reduced fronto-clypeal region is often termed the epistoma.
2012 C. Nielsen Animal Evol. (ed. 3) xxxviii. 210/1 The epistome is apparently controlling the ingestion of captured particles.
Derivatives
epiˈstomal adj.
ΚΠ
1857 Nat. Hist. Rev. 4 265 The second ring is nearly as deep as the third, and well marked; the epistomal plate narrow, and formed of two triangles placed apex to apex.
1977 O. W. Richards & R. G. Davies Imms's Gen. Textbk. Entomol. (ed. 10) II. 585 The head is prognathous..with epistomal, trans-clypeal, clypeolabral and postoccipital sulci.
2007 J. W. Shultz & R. Pinto-da-Rocha in R. Pinto-da-Rocha et al. Harvestmen ii. 23 The ventral epistomal surface is constructed from soft, flexible cuticle and often has a distal lobe.
This entry has been updated (OED Third Edition, March 2014; most recently modified version published online March 2022).
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