primary intergradation An intermediate zone between two phenotypically different populations, developed in situ as a result of selection. see secondary intergradation.
primary iris cells see corneal pigment cells primary ligament (MOLL: Bivalvia) Original ligamental structure consisting of periostracum, lamellar layer and fibrous layers; not secondary additions such as the fusion layer.
primary ocelli see dorsal ocelli primary/periodical pleometrosis (ARTHRO: Insecta) In social Hymenoptera, a colony founded by a group of queens, however, after emergence of the first workers, all but one female disperse. see secondary pleometrosis, temporary pleometrosis.
primary pigment cells see corneal pigment cells primary reproductive (ARTHRO: Insecta) In Isoptera, the queen or male termite derived from winged adults, that establish a colony. see adultoid reproductive, nymphoid reproductive, ergatoid reproductive.
primary riblet (MOLL: Bivalvia) In shells with various strength of riblets, the riblet appearing early in development and remaining stronger than later ones.
primary royal pair see primary reproductive primary segmentation The segmental division of the body originating in embryonic metamerism.
primary setae (ARTHRO: Insecta) In Lepidoptera, setae with a definite arrangement found on caterpillars in all instars.
primary sexual characters Gonads and associated ducts.
primary shell layer (BRACHIO) Outer layer under the periostracum; deposited by columnar epithelium of the outer mantle lobe.
primary somatic hermaphrodite see intersex primary spicule (PORIF) A major structural megasclere.
primary teeth (BRACHIO) The cardinalia or central teeth below the umbones.
primary zooid (BRYO: Gymnolaemata) In some Cheilostomata, the ancestrula or one to several zooids simultaneously budded after larval metamorphosis; differing from subsequent zooids.
primary zoological literature The literature dealing with animals or zoological phenomena, not merely a listing of names.
primaxil n. [L. primus, first; axis, axle] (ECHINOD: Crinoidea) The first axillary arm; the axillary primibrach.
primibrachs n.pl. [L. primus, first; Gr. brachion, upper arm] (ECHINOD: Crinoidea) All brachials of an unbranched arm; there are usually 2, the second of which is an axillary. primibrachial a.
primitive a. [L. primus, first] Ancestral; original form; primordial.
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