epiostracum n. [Gr. epi, upon; ostrakon, shell] (ARTHRO: Che-licerata) 1. A thin elastic, colorless layer of the cuticle of arachnids which overlies the ectostracum layer; further divided into two layers: inner, dense and proteinaceous, and outer, cuticulin. 2. The upper layer of cuticle of arachnids.
epipelagic a. [Gr. epi, upon; pelagos, sea] Pertaining to suspended organisms inhabiting an aquatic environment between the surface and a depth of 200 m. see mesope-lagic, bathypelagic.
epiphallus n. [Gr. epi, upon; phallos, penis] 1. (ARTHRO: In-secta) a. In male Orthoptera, a plate on top of the genital complex. b. In male Dictyoptera, a pair of valves dorsad of the phallus. 2. (MOLL: Gastropoda) A very muscular part of the sperm duct proximal to the penis sheath which participates in the formation of spermatophores.
epipharyngeal wall (ARTHRO: Insecta) The inner surfaces of the labrum and clypeal regions of the head.
epipharynx n. [Gr. epi, upon; pharynx, throat] (ARTHRO: Insecta) A small medium lobe on the interior surface of the labrum or clypeus. epipharyngeal a.
epiphragm n. [Gr. epi, upon; phragma, partition] (MOLL: Gastropoda) In land snails, a sheet of dried mucus across the aperture preventing loss of moisture during aestivation or hibernation.
epiphysis n.; pl. -ses [Gr. epi, upon; phyein, cause to grow]
1. (ARTHRO: Insecta) In Lepidoptera, a lamellate spur or process on the inner surface of the fore tibia bearing a dense brushlike array of setae. 2. (ECHINOD: Echinoidea) One of 5 small peripheral bars in Aristotle's lantern.
epipleura n.; pl. -rae [Gr. epi, upon; pleura, side] (ARTHRO: Insecta) In Coleoptera, the infolded lateral edge of the elytra.
epipleural sclerites (ARTHRO: Insecta) One or two small sclerites in the membranous area between the thoracic pleura and the wing bases that are important to wing movement due to muscle attachment.
epipleurum n. [Gr. epi, upon; pleuron, side] (ARTHRO: Insecta) 1. Among coleopterous larvae the lateral area above the ventrolateral suture and below the dorsolateral suture.
2. In ichneumonid Hymenoptera, the thin margin of the second and following abdominal segments.
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