University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln

Armand R. Maggenti Online Dictionary of Invertebrate Zoology Parasitology, Harold W. Manter Laboratory of

September 2005

Online Dictionary of Invertebrate Zoology: M

Mary Ann Basinger Maggenti University of California-Davis

Armand R. Maggenti University of California, Davis

Scott Gardner [email protected]

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Maggenti, Mary Ann Basinger; Maggenti, Armand R.; and Gardner, Scott, "Online Dictionary of Invertebrate Zoology: M" (2005). Armand R. Maggenti Online Dictionary of Invertebrate Zoology. 14. https://digitalcommons.unl.edu/onlinedictinvertzoology/14

This Article is brought to you for free and open access by the Parasitology, Harold W. Manter Laboratory of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Armand R. Maggenti Online Dictionary of Invertebrate Zoology by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. 528 On line Di ctio nar patterns and reaction syystoefms. see microevolution. Inve M macrofauna n. [Gr. makros, larger;tebL. Faunus, diety of herds rate and fields] 1. Widely distributed; fromZoao macrohabitat. 2. log Animals measured in centimeters rather thay n microscopic units. macerate v. [L. macerare, to soften] To waste away; to soften macrogamete n. [Gr. makros, large; gamete, wife] A large, or wear away. quiescent, female anisogamete. see microgamete. machopolyp, machozooid see dactylozooid macrogametocyte n. [Gr. makros, large; gamein, to marry; macraner n. [Gr. makros, large; aner, male] (ARTHRO: In- kytos, container] The infected human red blood cell that secta) A male ant of unusually large form. contains the female form of the malarial parasite which upon transfer to the Culicidae becomes a macrogamete. macrergate n. [Gr. makros, large; ergate, worker] (ARTHRO: Insecta) In Formicidae, an unusually large worker. macrogamy see hologamy macrobiota n. [Gr. makros, large; bios, life] Larger organisms macrogenesis n. [Gr. makros, large; genesis, origin] The sud- in the soil, such as insects and earthworms. see mesobi- den origin of new species by saltation. ota. macrogyne n. [Gr. makros, large; gyne, woman] (ARTHRO: In- macrocephalic female (ARTHRO: Insecta) In Hymenoptera, a secta) In Formicidae, a female or queen of unusually large large female of Halictidae, that possesses a disproportion- stature. ately large head, usually the egg layers of the colony. macroic see meganephridia macrocercous cercaria (PLATY: Trematoda) Cystophorous macrolecithal a. [Gr. makros, large; lekethos, egg yolk] With type cercaria with a long, simple, cylindrical tail. a large amount of yolk. see microlecithal. macrochaetae n.pl. [Gr. makros, large; chaite, hair] Large macromere n. [Gr. makros, large; meros, part] A distinctly bristles. see chaetotaxy. large cell resulting from unequal cleavages during early macrocilia n.pl.; sing. -ium [Gr. makros, large; L. cilium, embryology. eyelash] (CTENO) In Beroida, 2,500-3,500 giant ciliary macromesentery n. [Gr. makros, large; mesos, middle; en- shafts interconnected and bound together on the mobile teron, gut] (CNID: Anthozoa) One of the larger complete lips that function in food gathering. mesenteries. macrocnemes n.pl. [Gr. makros, large; kneme, lower leg] macromitosome n. [Gr. makros, large; mitos, thread; soma, (CNID: Anthozoa) In Actinaria, complete and filamented body] (ARTHRO: Insecta) The paranucleus as seen in Lepi- mesenteries in the first one or two cycles of simple tenta- doptera. cles; maybe fertile or sterile and possess acontia and macromolecule n. [Gr. makros, large; L. moles, mass] Very strong retractors. see microcnemes. large molecules such as protein, cellulose, starch, etc. macrocyte see plasmatocyte macromutation n. [Gr. makros, large; mutare, to change] macroesthetes see megalaesthetes Theory of instantaneous evolution of new taxa by a muta- macroevolution n. [Gr. makros, large; L. evolvere, to unroll] tion that establishes reproductive isolation at once. Evolutionary processes that extend through geologic eras; macronotal a. [Gr. makros, large; notos, back] (ARTHRO: In- large scale evolution of new species and genera due to secta) Having a large thorax, as a queen ant. mutations that result in marked changes in chromosomal 529 530 Maggenti and Gardner On line Di ctio nar macronucleocyte see prohemocyte macula n.; pl. maculae [L.y mofacula, spot] 1. A colored spot of Inv rather large size. 2. A spot leveretle with surrounding surface. macrophage n. [Gr. makros, large; phagein, to eat] A large bra 3. (BRYO: Stenolaemata) Prominencetes,Z and less commonly phagocytic cell of the body. ool flat or depressed areas on colony surfacesorgeygularly spaced macrophagous a. [Gr. makros, large; phagein, to eat] Feed- among feeding zooids caused by clusters of a few poly- ing on large objects. see microphagous. morphs, and/or extrazooidal skeleton. see monticule. 4. macrophthalmic a. [Gr. makros, large; ophthalmos, eye] (MOLL: Cephalopoda) An oval spot on the wall of a statocyst Having large eyes; having eyes larger than normal. to which a calcareous statolith is attached; gives informa- macroplankton n. [Gr. makros, large; planktos, wandering] tion on position relative to gravity. Large organisms such as jellyfish that drift with the cur- maculate a. [L. macula, spot] Splashed or spotted; blotched. rents. madrepore n. [L. mater, mother; Gr. poros, friable stone] macropore see megalopore (CNID) A stony, branched, reef building coral of the order macropseudogyne see pseudogyne Madreporia. macropterous a. [Gr. makros, large; pteron, wing] (ARTHRO: madreporic plate (ECHINOD: Asteroidea) An enlarged interra- Insecta) Having a long or large wing. see brachypterous. dial plate on the disc, that connects the water vascular system to the sea. macrosclere see megasclere madreporite n. [L. mater, mother; porus, pore] (ECHINOD) An macroscopic, macroscopical a. [Gr. makros, large; skopein, oral or aboral perforated plate of the water-vascular sys- to view] Capable of being studied with the unaided eye; tem connecting with the stone canal; sieve plate. megascopic. see microscopic. main bud (BRYO: phylactolaemata) The largest of three bud macroseptum n. [Gr. makros, large; L. septum, partition] 1. primordia which occurs on every mature zooid, and is the (CNID: Anthozoa) The variously functioning primary sep- first to form a new polypide. tum. 2. (NEMER) In asexual reproduction, a partition across the body marking the plane of subsequent fragmentation. major gene Controls production of qualitative phenotypic ef- fects in contrast to its modifiers. macrosiphon n. [Gr. makros, large; siphon, tube] (MOLL: Cephalopoda) Internal siphon of certain cuttlefishes, and all major worker (ARTHRO: Insecta) The largest worker subcaste octopuses. in social insects; in Formicidae, usually specialized for de- fense and referred to as a soldier. see media worker, mi- macrosymbiont n. [Gr. makros, large; symbios, living to- nor worker. gether] The larger of two symbiotic organisms. mala n.; pl. malae [L. mala, cheek, jaw] 1. A lobe; ridge or macrotaxonomy n. [Gr. makros, large; taxis, arrangement] grinding surface. 2. (ARTHRO) a. Part of the maxilla of cer- The classification of higher taxa. tain insects. b. Mandible of some myriapods. macrotrichia n.pl.; sing. -ium [Gr. makros, large; thrix, hair] malacoid a. [Gr. malakos, soft] Soft textured. 1. The larger surface hairs. 2. (ARTHRO: Insecta) The large hairs on the wing membrane. malacology n. [Gr. malakos, soft; logos, discourse] The branch of zoology dealing with mollusks, the animal inside macrotype n. [Gr. makros, large; typos, type] (CNID: Antho- the shell. zoa) Modified arrangement of mesenteries consisting mainly of macromesenteries. see microtype. malacophilous a. [Gr. malakos, soft; philios, loving] (MOLL: Gastropoda) Being pollinated by the action of gastropods. macrurous a. [Gr. makros, large; oura, tail] Long-tailed. 531 532 Maggenti and Gardner On line Di ctio nar malapophysis n.; pl. -ses [L. mala, cheek, jaw; Gr. apophy- extending into the bodyycoafvity from the posterior region of Inv sis, projection] (ARTHRO: Chelicerata) In Acari, the paired the gut in insects, arachnids anerdtemyriapods. bra anterior region of the infracapitulum. te Z maltha see mesogloea ool ogy malar a. [L. mala, cheek] Of or about the cheek region. mamelon n. [F. mamelon, protuberance] 1. (ECHINOD: Echin- malar cavity (ARTHRO: Chelicerata) In Acari, interior of the oidea) Terminal knob on the boss that articulates with the malapophysis that connects to the pharynx. spine on the test. 2. (NEMATA: Secernentea) Two or three male n. [L. mas, a man] An individual that produces sperm ventral, serrated projections on the ventral surface of the cells but not egg cells; designated by . male of the genus Syphacia; function unknown. male-cell receptacle (ARTHRO: Crustacea) In Rhizocephala, a mammillate a. [L. mamilla, small breast] Having rounded pocket or pair of pockets within the mantle cavity of the protuberances or wart-like projections; mammiform; female where cells of male cyprid undergo spermatogene- mammose. sis. manca n. [L. mancus, imperfect] (ARTHRO: Crustacea) In Pera- male ducts, male gonoducts see sperm ducts carida, a juvenile or postlarva that lack the last thoracopod when released from the marsupium. male funnel (ANN: Oligochaeta) A funnel or rosette-shaped enlargement of the ental end of the sperm duct for passage manchette n. [F. manchette, cuff] (NEMATA) Line of demarca- of sperm through the central aperture into lumen of the tion between the cheilostome and esophastome; nema's duct on their way to the exterior. collar; sleeve. malella n. [L. dim. mala, jaw] (ARTHRO: Symphyla) The distal mancoid stage (ARTHRO: Crustacea) Postlarval stage in Lepto- toothed process on the outer stipes of the deutomala of straca, with rudimentary 4th pleopod. some myriapods. mandible n. [L. mandibula, jaw] 1. A jaw. 2. (ANN: Polychaeta) male tube (ECHI) A sexually maturing area in which developing The ventral chitinous plates or rods, maybe dentate, males are housed for one to two week inside the female. against which the maxilla work. 3. (ARTHRO: Crustacea) One of the third pair of cephalic appendages. 4. (ARTHRO: malleate mastax (ROTIF) Chewing apparatus; rami untoothed Diplopoda) The first pair of jaws, consisting of cardo, stipes and unci are curved plates with prong type teeth. and gnathal lobe. 5. (ARTHRO: Insecta) One of the variously malleations n.pl. [L. dim. malleus, hammer] A hammered ap- modified anterior pair of paired mouthpart structures. 6. pearance. (BRYO) A modified orificial wall of the avicularium. see op- malleolus n.; pl. -li [L. dim. malleus, hammer] 1. (ARTHRO: erculum. Chelicerata) In Solpugida, 3 to 5 innervated appendages on mandibular fossa (ARTHRO: Insecta) The dorsal articulation of the coxae and trochanter of the fourth leg; function uncer- the mandible. tain; racket-organs. 2. (ARTHRO: Insecta) see haltere. mandibular gland (ARTHRO: Insecta) A sac-like reservoir usu- malleoramate mastax (ROTIF: Monogononta) Chewing appa- ally paired, and partially or completely lined by secretory ratus, variant of the ramate type of mastax occurring in the cells, opening in the mesal junction of the mandible with order Flosculariaceae. the head; functioning as alarm pheromone, fungistatic malleus n.; pl. malli [L. malleus, hammer] (ROTIF) Unci and agent, aggregation pheromone, sex pheromone, territory manubria of the mastax, collectively. defending secretion, location of food and/or the 'burning' secretion of the 'fire bees'; in larval Lepidoptera, large and Malpighian tubules (ARTHRO) Long, thin excretory tubules secrete saliva (with the normal salivary glands specialized 533 534 Maggenti and Gardner On line Di ctio nar for silk production). envelopes or covers. 2y. o(fARTHRO: Crustacea) In thoracic Inve mandibular palp 1. (ARTHRO: Crustacea) In Cirripedia, distally Cirripedia, membranous coverrteinbg of the body, often rate articulated part of the mandible functioning in feeding or strengthened by calcareous plates. 3. Z(oBoRACHIO) Prolonga- log cleaning; in Acrothoracica associated with the mandibular tion of the body wall as fold of ectodermalyepithelium. 4. gnathobase; setose lobe on labrum. 2. (ARTHRO: Insecta) (BRYO: Phylactolaemata) Ciliated fold of colony wall cover- see prostheca. ing one to four small, sexually produced colony progenitor polypides. 5. (MOLL) A membranous covering that secretes mandibular plates (ARTHRO: Insecta) In Hemiptera, plates the shell; the marginal glands produce the periostracum; between and attached to the mandibular stylets and the pallium. ventral surface of the sucking pump. mantle canal (BRACHIO) One of several flattened, tube-like mandibular pouch (ARTHRO: Insecta) In Thysanoptera, a extensions of the body cavity into each mantle lobe. ventrally oriented cone formed by the labrum and labium containing maxillary stylets and a single (left) functional mantle cavity Specialized cavity found in certain mollusks, mandible, emerging at the apex. brachiopods and crustaceans lined with epidermis and usu- ally exposed to sea or fresh water, or air, due to habitat; mandibular ring (NEMATA: Adenophorea) In Enoplida, trans- may or may not contain part of the viscera; pallial chamber verse extension of the mandibles in the buccal cavity. or cavity; mantle chamber. mandibular scar (ARTHRO: Insecta) In certain Coleoptera pu- mantle cells (ARTHRO: Insecta) Corneagenous cells of the eye pae, round or oval areas with raised margins that serve as enclosing the retina. supports for the deciduous provisional mandibles. mantle fold (MOLL: Bivalvia) In oysters, one of 3 small folds at mandibular sclerite (ARTHRO: Insecta) In some larval Diptera, the edge of a mantle lobe. mouth-hooks articulating basally with the intermediate (hypostomal) sclerites. mantle groove (BRACHIO) Site of proliferation of the perio- stracum and bears the setae. Mandibulata n. [L. mandibula, jaw] Formerly a subphylum of arthropods including Myriapoda, Crustacea and Insecta. mantle lobe 1. (BRACHIO) Lobe of the body wall that secretes and lines the valves; in some, cecae project into perfora- mandibulate a. [L. mandibula, jaw] Having jaws fitted for tions (punctae) in the shell serving as food repositories of chewing; mandibuliform. glycoproteins and mucroproteins, inhibitors of boring or- manducate v. [L. manducare, to chew] To bite; eat. ganisms, and accessory respiratory structures. 2. (MOLL: manica n. [L. manica, sleeve] (ARTHRO: Insecta) In Lepidop- Bivalvia) In oysters, one of 2 thin epithelial extensions of tera, the inner layer of the anellus, that fastens around the the mantle adjoining the valve. aedeagus. mantle papilla see caecum maniform a. [L. manus, hand; forma, shape] Hand-shaped. mantle skirt (MOLL) Roof of the mantle cavity formed by the manitruncus see prothorax projection of the mantle from the edge of the visceral mass. manna n. [Gr. manna, morsel or honey dew] (ARTHRO: In- secta) Honeydew (90-95% sugar) produced by certain coc- manubrium n. [L. manubrium, handle] 1. (ARTHRO: Crustacea) cids, used as human food. In fish parasitic Copepoda, the handle or distal part of the attachment organ. 2. (ARTHRO: Insecta) The basal part of manometabola see hemimetabolous metamorphosis the furcula of collembolan springtails; part of the sternum mantle n. [L. mantellum, cloak] 1. Something that enfolds, associated with the cavity of the prothorax of Coleoptera. 535 536 Maggenti and Gardner On line Di ctio nar 3. (CNID: Hydrozoa) The extension between the stomach to posteroventral angle yoof fthe shell delimiting the posterior Inve cavity and the mouth of a medusae or polyp; also called area in Trigoniacea. rteb rate gullet or esophagus. 4. (NEMATA) The proximal portion of a marginal veins (ARTHRO: Insecta) A veiZnoorunning along the log spicule; a capitulum. 5. (ROTIF) One of two paired trophi in front margin of a wing that gives off a stigmayl vein. the mastax. marginate a. [L. margo, border] Having a distinct margin in manus n. [L. manus, hand] 1. The hand. 2. (ARTHRO: Crusta- appearance or structure. cea) Broad proximal part of a propodal cheliped of a Deca- poda. 3. (ARTHRO: Insecta) Formerly applied to the anterior marine a. [L. mare, sea] Pertaining to or inhabiting the sea, tarsus. 4. (MOLL: Cephalopoda) see tentacle. ocean, or other salt waters. manuscript name An unpublished scientific name. see nomen marita n. [L. maritus, conjugal] (PLATY: Trematoda) A sexually nudum. mature fluke. marble gall (ARTHRO: Insecta) The hard spherical gall of marker gene Genetic marker; gene of known position and Cynipidae Adleria kollari , usually on oak that produce the conspicuous in its action. agamic generation of that species. marmorate a. [L. marmor, marble] Having color or veined like margaritaceous a. [Gr. margarites, a pearl] Pearly in texture; marble. nacreous. marsh n. [A.S. mersc, marsh] An area of wet soil. margin n. [L. margo, border] 1. A border or an edge. 2. (AR- marsupium n. [L. marsupium, bag] 1. Brood pouch. 2. (AR- THRO: Insecta) The edge of a wing. 3. (CNID: Anthozoa) THRO: Crustacea) The oostegite in Peracarida, or brood The junction of the oral disk and collum of a sea anemone. chamber or pouch in others. 3. (ARTHRO: Insecta) In mar- 4. (MOLL) The edge of a shell. marginal a. supial coccids, a waxen ovisac, longer than the body, filled marginal bodies (PLATY: Trematoda) In Aspidogastrea, sen- with eggs that hatch while the insect is still mobile. 4. sory pits or short tentacles between marginal loculi of the (BRYO) The ovicell. 5. (CNID: Hydrozoa) In some, the inter- opisthaptor. nal pouch borne by the blastostyle. 6. (ECHINOD) a. In some, the cardiac stomach. b. In Viviparous Crinoidea, pre- marginal bristles (ARTHRO: Insecta) In Diptera, abdominal sent on the base of the pinnules adjacent to the gonad and bristles inserted dorsally on the margins of the segment. having an external opening; a brood chamber. marginal cell (ARTHRO: Insecta) A cell in the distal part of the mask n. [Ar. maskhara, buffoon] (ARTHRO: Insecta) In dragon- wing bordering the costal margin. fly nymphs, the prehensile labium that conceals the other marginalia n. [L. margo, border] (PORIF) Spicules protruding mouthparts. masked a. upward around an oscule. masked pupa see pupa larvata marginal nuclei (NEMATA) Nuclei of marginal cells in the mass communication (ARTHRO: Insecta) In Hymenoptera, nematode esophagus; believed to lay down the fibers from transfer of information among large groups of individuals the apex of the lateral arm to the basement membrane of which cannot be accounted for by one to one communica- the esophagus, or to secrete the cuticular lining of the tion. esophagus, or both. mass provisioning (ARTHRO: Insecta) Social behavior of soli- marginal tubes (NEMATA) The distal cylindric endings of some tary bees and wasps by storing cells with sufficient food to esophageal radii, other forms have convergent terminals. satisfy their developing offspring and closing them down marginal carina (MOLL: Bivalvia) A ridge running from umbo before the eggs hatch. see progressive provisioning. 537 538 Maggenti and Gardner On line Di ctio nar mastax n. [Gr. mastax, jaws] (ROTIF) A muscular rounded, leading to the destructioynoof f the female by the larvae or ju- Inve trilobed, or elongate organ containing trophi; in suspension veniles; eclosion intrauterine. rteb rate feeders adapted for grinding, in carnivores modified as for- matrifilial a. [L. mater, mother; filia, dauZgohoter] (ARTHRO: In- log ceps that can be projected from the mouth to seize prey; secta) In Apis, having colonies made up oyf mothers and the pharynx. daughters. mastication n. [L. mastecare, to chew] The act of chewing; to matrix n.; pl. matrices [L. mater, mother] 1. That which gives grind or crush. form, origin or foundation to something enclosed or em- masticatory process see gnathal lobe bedded in it. 2. (NEMATA: Secernentea) The gelatinous sub- masticatory stomach see gastric mill stance secreted by some female nematodes into which eggs are deposited to form an egg mass. 3. (PLATY) In masticomorphic a. [L. mastecare, to chew; Gr. morphos, Cestoda and Trematoda, a living interface of interacting form] Designed for chewing. photoplasmic layer; part of the syncytium of the tegument. mastidia n.pl.; sing. mastidion [Gr. mastos, breast] (ARTHRO: 4. (PORIF) The non-cellular ground material of a sponge in Chelicerata) Small, conical, nipple-like tubercles on the which the cellular elements are dispersed. front of the chelicerae of small spiders. matrix glands (NEMATA: Secernentea) An excretory cell or mastigobranch, mastigobranchia n. [Gr. mastix, whip; modified rectal glands that secrete the gelatinous matrix branchos, gill] (ARTHRO: Crustacea) A slender respiratory through the anus or excretory pore and into which eggs process at the base of the epipod. maybe imbedded. mastigophore n. [Gr. mastix, whip; pherein, to bear] (CNID: matrix layer (NEMATA) Historically, a cuticular stratum of Anthozoa) A nematocyst with a cylindrical hempe and tube spongy material between the fibrillar layer and the bound- extending beyond the hempe; microbasic with hempe not ary layer. more than 3 times the capsule length; macrobasic with matrone n. [L. mater, mother] (ARTHRO: Insecta) Macromo- hempe 4 or more times the capsule length. lecular components (proteins) contained in the seminal mastigopus larva (ARTHRO: Crustacea) Larva in the megalopa fluid of some male Culicidae that inhibits further insemina- stage found among some Decapoda. tion of the female. maternal inheritance Inheritance controlled by maternal ex- maturation n. [L. maturus, ripe] The act or process pertaining tra chromosomal determinants. to the developmental steps leading to reproducing adults. maternal zooid (BRYO: Gymnolaemata) An autozooid that ex- maturation divisions A series of nuclear divisions in the for- trudes eggs. mation of the gametes in which the chromosome number, mating plug (ARTHRO: Insecta) A plug formed from the acces- through meiosis is reduced from diploid to haploid. sory gland secretions of the male, deposited in the genital maturation feeding (ARTHRO: Insecta) Feeding required by chamber of the female, thought to prevent loss of sperm in some insects before their gonads can mature to produce some Culicidae and Lepidoptera; also called spermato- eggs. phragma. see sphragis. maturation zone In males of many invertebrates, that part of mating spines (ARTHRO: Insecta) In female mayflies, com- the genital follicle below the germarium in which each pound conical spines covering the lower surface of the egg spermatocyte undergoes the two meiotic divisions to pro- valve. duce spermatids. see transformation zones. matricidal hatching (NEMATA) Intrauterine larval development mature region see exozone 539 540 Maggenti and Gardner On line Di ctio nar maxaponta n. [L. maxilla, jaw; pons, bridge] (ARTHRO: In- forms, the non-functionyaol fappendages between mandibles Inv secta) A bridge formed by a midline fusion of the lower and first maxillae. see superlienrgteuae. bra maxillariae and the postgenae. maxapontal a. te Z maxim n. [L. maximus, greatest] (ARTHRO:ooIlnsecta) In Formi- ogy maxilla n.; pl. -llae [L. maxilla, jaw] 1. (ANN: Polychaeta) The cidae, a major worker or one of the soldier caste. large, hook-shaped, dorsal chitinous jaw plate. 2. (ARTHRO) mayrian furrow see notaulix In most arthropods, one of the paired mouth-part struc- tures posterior to the mandibles or jaws; third pair of head meatal cleft (ARTHRO: Insecta) A slit or line on the trumpet of appendages. 3. (ARTHRO: Diplopoda) One of the paired some mosquito pupae extending into the meatus from the second jaws to form the gnathochilarium. spiracular opening, facilitating enlargement of the opening at the surface of the water. maxillary a. [L. maxilla, jaw] (ARTHRO) Of or pertaining to the maxilla. meatus n. [L. metus, passage] A channel or duct. maxillary carrier (ANN: Polychaeta) A posterior support mechanical isolation Reproductive isolation due to mechani- structure for the maxilla. cal incompatibility of male and female genitalia. maxillary glands (ARTHRO) Glands belonging to the maxillary mechanoreceptor n. [Gr. mechane, contrivance; L. recipere, segment, possibly functioning in the lubrication of the to receive] Specialized structures that perceive any me- mouthparts. chanical distortion of the body, i.e., touch, vibrations, alti- tude and gravity. maxillary guides (ARTHRO: Insecta) In Anoplura, paired structures of wrinkled sucking lice arising from the maxil- meconida n.pl.; sing. -ium [Gr. mekon, poppy] 1. (ARTHRO: lary appendages that function as guides for the dorsal Insecta) Waste products of pupal metabolism that are dis- stylet. charged shortly after adult emergence. 2. (CNID: Hydrozoa) Medusoid gonophores, sessile or pedicellate, which upon maxillary palp/palpus; pl. -pi (ARTHRO: Insecta) Small sen- emergence from the gonangium act as external brood sacs. sory organ arising from the maxilla, used to test quality of meconium n. food. see labial palp. media n. [L. medius, middle] 1. The middle structure. 2. (AR- maxillary segment see maxillulae THRO: Insecta) The longitudinal vein between the cubitus maxillary stylets (ARTHRO: Insecta) In Hemiptera, the inner and the radius of the wing. medial a. pair of stylets of the trophic sac. mediad adv. [L. medius, middle; ad, toward] Toward the me- maxillary tentacle (ARTHRO: Insecta) In female Tegeticula dian plane or line; mesad; admedial. Lepidoptera, an inner elongate lobe of the maxilla, adapted medial cross vein (ARTHRO: Insecta) A cross vein connecting for holding a large mass of pollen; perhaps palpifers. two branches of the media of the wing. maxilliped, maxillipede, maxillipe a. [L. maxilla, jaw; pes, medial-cubital cross vein (ARTHRO: Insecta) A cross vein of foot] (ARTHRO: Crustacea) The paired appendages on tho- an insect wing between the posterior medial vein and the racic somites 1-3 posterior to the maxillae, that usually anterior cubital vein. function in feeding; sometimes adapted for other functions such as prehension in parasitic forms. median a. [L. medius, middle] In the middle; along the midline of the body; middle variate when variates are arranged in maxillulae n.pl.; sing. -ula [L. dim. maxilla, jaw] 1. (ARTHRO: order of magnitude. Crustacea) The first maxillae having more than one pair of maxillae; paragnath. 2. (ARTHRO: Insecta) In primitive median bulb see metacorpus 541 542 Maggenti and Gardner On line Di ctio nar median caudal nerve (NEMATA) A nerve extending from the mediolateral nerve cord (yNoEfMATA) Several nerves extending Inv dorsorectal ganglion to the tail. from the median and posterioerrteexternolateral ganglia and bra the posterior internolateral ganglia totetZhe lumbar ganglia. median cercus see urogomphus ool ogy median cord (ARTHRO: Insecta) An embryonic chain of cells mediotergite n. [L. medius, middle; tergum, back] (ARTHRO: derived from the ectoderm lining the neural groove. Insecta) In Diptera, the median region of the mesopostno- tum. median dorsal plate (ARTHRO: Crustacea) In some Peracardia, an elongate plate separating carapace valves posterodor- medioventral a. [L. medius, middle; venter, belly] In the mid- sally. dle ventral line. median esophageal bulb see metacorpus mediproboscis see haustellum median eye see nauplius eye medulla n. [L. medulla, marrow, pith] 1. Central portion of an organ. 2. (ARTHRO) Apical lobes of the brain; the central median lamina see median wall synaptic region; epiopticon; medulla externa; external me- median latus (ARTHRO: Crustacea) In Lepadomorpha, a plate dullary mass. between the rostral and carinal latera in forms with paired medulla externa see medulla latera in one whorl. see lateral. medulla interna (ARTHRO: Insecta) The lobular complex. median ligament (ARTHRO: Insecta) A common thread formed by the ovarioles of opposite sides that help maintain the medulla X-organ, medulla terminalis ganglionic X-organ, ovaries in position and is attached to the body-wall, the MTGX (ARTHRO: Crustacea) A group of neurosecretory cells fat-body or the pericardial diaphragm. in the medulla terminalis; the main source of eyestalk hormones. median oviduct see common oviduct medusa n.; pl. -sae [L. Medusa, a gorgon of mythology] median segment (ARTHRO: Insecta) The basal segment of the (CNID) The free swimming umbrella-like forms. abdomen when it is fused with the metathorax during the change from larva to pupa. see propodeum, epinotum. megabenthos see abyssobenthos median tubuli (BRYO: Stenolaemata) Aligned pustules or mu- megacephalic a. [Gr. megas, large; kephale, head] Having an ral lacunae in a laminated skeleton. abnormally large head. see microcephalic, meso- cephalic. median valve see intermediate valve megaclad n. [Gr. megas, large; klados, branch] (PORIF) In median wall (BRYO: Stenolaemata) Erect colony wall parallel megascleres, a relatively large smooth desma; megaclone. to the growth direction from which zooids bud to form a bifoliate colony. megaclone see megaclad mediator n. [L. medius, middle] Association, internuncial, megadrile n. [Gr. megas, large; drilos, worm] (ANN: Oli- neuron; chemical such as a hormone that controls or modi- gochaeta) Terrestrial forms; not used systematically, al- fies a metabolic process. though recognized as a general term. see microdrile. media worker (ARTHRO: Insecta) In Formicidae, an individual megalaesthetes n.pl. [Gr. megas, large; aisthesis, sensation] belonging to the medium-size subcaste in a polymorphic (MOLL: Polyplacophora) Large sensory organs terminating series of three or more worker subcastes. see minor in the tegmentum in the forms of eyes with cornea, lens, worker, major worker. pigment layers, iris and retina. see micraesthetes. medio-cubital cross vein see medial-cubital cross vein megalolecithal see macrolecithal 543 544 Maggenti and Gardner On line Di ctio nar megalopa stage (ARTHRO: Crustacea) 1. Larvae of Mala- sea bottom. y of Inv costraca with functional pleopods; also referred to as glau- erte meiolecithal a. [Gr. meion, smaller; blerkaithos, egg yolk] Having cothoe. 2. First postlarval stage in development of Eu- te Z little yolk. ool carida, not present in other crustaceans. 3. Originally ap- ogy plied to Brachyura larvae with large stalked eyes and func- meiomery n. [Gr. meion, smaller; meros, part] The condition tional pleopods. of possessing fewer than the normal number of parts. megalopore, megapore n. [Gr. megas, large; poros, pore] meiosis n.; pl. meioses [Gr. meiosis, to make smaller] Two (MOLL: Polyplacophora) Large pore in the dorsal plate; as- successive cell divisions in the developing germ cells char- sociated with aesthete. acterized by the pairing and segregation of homologous chromosomes, resulting in reduction from a diploid number megalops see megalopa stage to a haploid one. meiotic a. megamere see macromere meiotic drive A meiotic mechanism of cell division resulting in megameric a. [Gr. megas, large; meros, part] With relatively two kinds of gametes produced by a heterozygote with un- large parts; autosomes with large heterochromatic seg- equal recovery. ments. meiotrichy n. [Gr. meion, smaller; thrix, hair] Loss of setae in meganephridia n.pl.; sing. -ium [Gr. megas, large; dim. ontogenetic development or of homologous setae in natural nephros, kidney] (ANN: Oligochaeta) A pair of large groups. nephridia in each segment of the body except, for first and melania n. [Gr. melas, black] Blackness. last segments; holonephridia; holoic; macroic. see nephridium, micronephridia. melanin n. [Gr. melas, black] A term for a group of chemically ill-defined pigments, often found associated with protein, megaplankton see macroplankton produced by insects and marine animals responsible for megasclere n. [Gr. megas, large; skleros, hard] (PORIF) A colors from brown to black. melanoid a. large structural spicule. see microsclere. melanism n. [Gr. melas, black; ismos, denoting condition] 1. megascolecin n. [Gr. megas, large; skolex, worm] (ANN: Oli- An excessive darkening of color owing to increased gochaeta) The single pair of prostates, tubular or ra- amounts of black pigment. 2. A certain percentage of indi- cemose, opened to the exterior, along side of or together viduals in a population that give rise to polymorphism. see with the sperm ducts. industrial melanism, albinism. megascopic see macroscopic melanoid a. [Gr. melas, black; eidos, like] Looking black or megetic a. [Gr. megas, large] Pertaining to size variations in dark. polymorphic forms. see epimegetic, eumegetic, hy- meliphagous a. [Gr. meli, honey; phagein, to eat] Honey- pomegetic. eating; melivourous. Mehlis' glands (PLATY: Trematoda) Unicellular mucous and melittology n. [Gr. melitta, honeybee; logus, discourse] The serous glands surrounding the ootype in the reproductive study of bees. system. melittophily n. [Gr. melitta, honeybee; philos, love] (ARTHRO: meiocyte n. [Gr. meion, smaller; kytos, container] Primary oo- Insecta) 1. A symbiont of social bees. 2. Any organism that cytes and spermatocytes. must spend a portion of its life cycle in a bee colony. meiofauna n. [Gr. meion, smaller; L. Faunus, diety of herds melivorous see meliphagous and fields] Microscopic and small macroscopic fauna on the 545 546 Maggenti and Gardner On line Di ctio nar mellifera n. [L. mel, honey; ferre, to bear] (ARTHRO: Insecta) THRO: Insecta) Having byiotifng mandibles in both larval and Inve Honey-makers; bees as a whole. adult stages. menognathous ar.tebsee Menorhyncha, me- rate melliferous a. [L. mel, honey; ferre, to bear] Honey produc- tagnath. Zoo log ing. Menorhyncha n.pl. [Gr. menein, to remain; rhy nchos, snout] mellisugent a. [L. mel, honey; sugere, to suck] Honey-suck- (ARTHRO: Insecta) A former division of insects composed of ing. those who ingest by suction in both larval and adult stages. see menognath and metagnath. member n. [L. membrum, part] A limb or organ. menotaxis n. [Gr. menein, to remain; taxis, arrangement] membrane n. [L. membrana, skin] A thin film of tissue. Orientation in a fixed direction with respect to the stimulus. membranization n. [L. membrana, skin] Changed into a mental a. [L. mentum, chin] Of or pertaining to the mentum. membrane. mental plate (ARTHRO: Insecta) In Lepidoptera, representing membranous a. [L. membrana, skin] Consisting of mem- the basal sclerites of the labium. see labial plate. branes; soft and pliable; membranaceous. mental setae (ARTHRO: Insecta) Setae located on the men- membranous sac (BRYO: Stenolaemata) Membrane surround- tum. ing digestive and reproductive systems of zooid; the ento- saccal and exosaccal cavity. mental suture (ARTHRO: Insecta) A distinct sclerite defined by a suture intervening between the mentum and the gula. membranule, membranula n. [L. dim. membrana, skin] (AR- THRO: Insecta) A small semi-opaque membrane on the mentasuture see mental suture base of the hind wing of certain Odonata. mentigerous a. [L. mentum, chin; gerere, to bear] (ARTHRO: Mendelian character Character formed under the control of Insecta) Having a mentum. chromosomal genes. mentum n. [L. mentum, chin] 1. (ARTHRO: Diplopoda) A me- Mendelian inheritance Mode of inheritance from chromoso- dian, slightly triangular sclerite in the gnathochilarium. 2. mal genes. (ARTHRO: Insecta) a. The distal sclerite of a typical insect labium, bearing the palps and the ligula. b. In bees, the Mendelian mutation True gene mutation and recombination. second joint bearing the palps, paraglossa and ligula. Mendelian population A population with unrestricted inter- meraspis larva (ARTHRO: Trilobita) The second larval stage breeding of organisms sharing a common gene pool. with the pygidium located behind the cephalon; the tho- Mendelism n. [Gregor Mendel] Particulate inheritance of racic region will appear during succeeding molts. see ho- chromosomal genes. laspis larva. Mendel's laws of inheritance Genetic principles proposed by merdivorous see scatophagous Mendel; law of segregation and law of independent assort- mereopodite see merus ment. meridional canal (CTENO) One of the eight canals extending in meniscoidal a. [Gr. meniskos, a crescent] 1. Crescent-shaped an oral-aboral direction under the external surface; part of lens; concavo-convex lens; one side convex and the other the gastrovascular system; in Pleurobranchia it emits a concave. 2. With one side concave, crescent shape of water greenish-blue luminescence. in a tube, or convex, crescent-shaped as with mercury in a tube. meristal annuli (ARTHRO: Insecta) In Orthoptera and Odonata, annuli derived from, and adjacent to, the meriston that di- menognath n. [Gr. menein, to remain; gnathos, jaw] (AR- 547 548 Maggenti and Gardner On line Di ctio nar vides. merognathite see merus y of Inv erte meriston n. [L. merizein, to divide] (ARTHRO: Insecta) The meroic a. [Gr. meros, part] (ANN: Oblriagochaeta) Pertaining to te Z most basal annulus of the antennal flagellum. the excretory system with nephridial otoulbules formed by ogy meritrichy a. [Gr. meros, part; trichos, hair] (ARTHRO: Cheli- longitudinal or transverse fragmentation of the original sin- cerata) In Acari, chaetotaxy characterized by a reduction in gle pair of embryonic rudiments of each segment. number and size of setae from the holotrichous form. meroistic ovariole (ARTHRO: Insecta) An ovariole in which mermithaner n. [Gr. mermis, cord; aner, male] (ARTHRO: In- nurse cells, or trophocytes are present; telotrophic (acro- secta) Male Formicidae parasitized by the nematode Mer- trophic) and polytrophic types; panoistic; meroistic egg mis; a mermithophore. tube. mermithergate n. [Gr. mermis, cord; ergates, worker] (AR- meromyarian a. [Gr. meros, part; mys, muscle] (NEMATA) THRO: Insecta) In Formicidae, a worker parasitized by the Muscle arrangement with only a few, frequently only two, nematode Mermis; a mermithophore. flat muscle cells seen in each quadrant of a cross section of the animal. mermithized a. [Gr. mermis, cord] (NEMATA) Pertaining to parasitism by nematodes of the genus Mermis. meron n. [Gr. meros, upper thigh] (ARTHRO: Insecta) The posterior part of the basicoxite; in higher Diptera, sepa- mermithodinergate see mermithostratiote rated from the coxa and forms part of the thoracic wall mermithogyne n. [Gr. mermis, cord; gyne, woman] (ARTHRO: (mesomeron, metameron). Insecta) A female Formicidae parasitized by the nematode meronephridium see micronephridia Mermis; a mermithophore. meropleuron n.; pl. -ura [Gr. meros, part; pleuron, side] (AR- mermithophore n. [Gr. mermis, cord; pherein, to carry] THRO: Insecta) A sclerite composed of the meron of the (NEMATA) An anomalous form resulting from parasitism by coxa and the lower region of the epimeron. the nematode Mermis; a mermithaner, mermithergate, mermithogyne, mermithostratiote. meropodite n. [Gr. meros, part; pous foot] (ARTHRO) 1. The fourth segment of a generalized limb. 2. The femur in Che- mermithostratiote n. [Gr. mermis, cord; stratiotes, soldier] licerata and Insecta. 3. For Crustacea see merus. (ARTHRO: Insecta) Soldier Formicidae parasitized by the nematode Mermis; a mermithophore. merosome n. [Gr. meros, part; soma, body] A body segment; a somite or metamere. mermitoid esophagus see stichosome merospermy n. [Gr. meros, part; sperma, seed] Fusion of an meroandry n. [Gr. meros, part; aner, male] The condition of egg cell with a sperm that has lost its nucleus; therefore, it possessing less than the normal number of testes. cannot take part in karyogamy with the egg nucleus. meroandric a. see holandry. merus n. [Gr. meros, part] (ARTHRO: Crustacea) The fourth meroblastic cleavage Cleavage of a heavily yolked egg in segment of the mouth part, articulating with the ischium which only the egg cell divides, leaving the yolk undivided. anteriorly and carpus posteriorly; a meropodite. merocerite n. [Gr. meros, part; keras, horn] (ARTHRO: Crusta- mesad, mesiad adv. [Gr. mesos, middle; ad, toward] Toward cea) The 4th segment of an antenna. the midline of the body. merocrine a. [Gr. meros, part; krinein, to separate] The mesadenia n.pl.; sing. mesadene [Gr. mesos, middle; aden, passing of a secretion by a gland in which the nucleus re- gland] (ARTHRO: Insecta) 1. Mesodermal accessory glands mains intact and thereby can recover. see holocrine. of male genitalia. 2. In some male Heteroptera, paired, 549 550 Maggenti and Gardner On line Di ctio nar highly coiled tubules that run side by side to enter anteri- mesepimeron n.; pl. -meyroaf [Gr. mesos, middle; epi, on; Inve orly the bulbus ejaculatorius or closely associated with the meros, part] (ARTHRO: Insectar)te1b. The area of the meso- rate short vasa deferentia. pleuron posterior to the mesopleural sZuotoure; the epimeron log mesal, mesial a. [Gr. mesos, middle] At or near the midline of of the mesothorax. 2. In Odonata, the areya between the the body. humeral and first lateral suture. mesal penellipse (ARTHRO: Insecta) In larvae, a series of cro- mesepisternum n.; pl. -sterna [Gr. meros, middle; epi, on; chets covering at least the mesal half of the proleg, incom- sternum, chest] (ARTHRO: Insecta) 1. The area of the plete laterally. see penellipse. mesopleuron anterior to the mesopleural suture; some- times divided into an upper mesanepisternum and a lower mesanapleural suture (ARTHRO: Insecta) In Diptera, a suture meskatepisternum; the episternum of the mesothorax. 2. between the mesanepisternum and the meskatepisternum. In Diptera, horizontally divided into a large mesanepimeron mesanepisternum n. [Gr. mesos, middle; ana, up; epi, on; but with a minute meskatepimeron below. 3. In Hymenop- sternon, chest] (ARTHRO: Insecta) 1. In Diptera, the upper tera Ichneumonidae, usually termed mesopleurum. area of the mesepisternum separated from the mesiad see mesad meskatepisternum by the mesanapleural suture; some- times divided into anterior and posterior by anepisternal mesial see mesal cleft; the anepisternum. 2. In Odonata, the anepisternum. mesial sclerite see labellar mesial sclerite mesaxon n. [Gr. mesos, middle; axon, axel] (ARTHRO: Insecta) mesic a. [Gr. mesos, middle] Climate characterized by a mod- The spiral arrangement of a Schwann cell around an axon; erate amount of water. suspensory fold. mesinfraepisternum n. [Gr. mesos, middle; L. infra, below; mesenchymatous cell see hemocyte Gr. epi, on; sternon, chest] (ARTHRO: Insecta) A ventral mesenchyme, mesenchyma n. [Gr. mesos, middle; en- subdivision of the mesepisternum. chyma, infusion] Embryonic connective tissue derived pri- meskatepimeron n. [Gr. mesos, middle; kata, inferior; epi, marily from mesoderm and consisting of a diffuse network on; meros, part] (ARTHRO: Insecta) The lower division of of loosely connected or scattered cells not segregated into the mesepimeron. layers or blocks. meskatepisternum n. [Gr. mesos, middle; kata, inferior; epi, mesenteron n. [Gr. mesos, middle; enteron, gut] The midgut on; sternon, chest] (ARTHRO: Insecta) In Diptera, the lower or midportion of the alimentary tract, endodermal in origin; area of the mesepisternum. ventriculus; midintestine. mesobasisternum n. [Gr. mesos, middle; basis, bottom; ster- mesenteron rudiments (ARTHRO: Insecta) Groups of em- non, chest] (ARTHRO: Insecta) 1. The basisternum of the bryologic endodermal cells that regenerate the midgut mesothorax. 2. In Diptera, maybe separated from the (stomach) including the anterior and posterior; becomes mesofurcasternum by a secondary line of inflection. see the epithelium of the adult mesenteron. furcasternum. mesentery n. [Gr. mesos, middle; enteron, gut] A supporting mesobiota n. [Gr. mesos, middle; bios, life] Organisms in the membrane or one that forms a partition. soil ranging in size from nematodes to microannelids, mi- mesepimeral scale or seta (ARTHRO: Insecta) Any scale or croarthropods and mites; mesofauna. seta borne on the mesepimeron. mesoblast n. [Gr. mesos, middle; blastos, bud] Embryonic mesepimeral suture see mesopleural suture mesoderm; the middle germ layer. mesoblastic a. 551 552 Maggenti and Gardner On line Di ctio nar mesoblastic somites Segmental divisions of embryonic all animals above the Cnyidoaf ria. Inv mesoderm. erte mesodermal tube The dorsal blood vbersasel; heart. te Z mesobranchial lobe or area (ARTHRO: Crustacea) In Deca- ool mesodont a. [Gr. mesos, middle; odous, toootghy] (ARTHRO: In- poda, an intermediate part of the branchial region of the secta) Pertaining to male Lucanidae bearing mandibles in- carapace. termediate in size; amphiodont. see teleodont, priodont. mesocardiac ossicle (ARTHRO: Crustacea) In Decapoda, a tri- meso-epinotal suture (ARTHRO: Insecta) In Formicidae, the angular or oblong plate, the apex pointing forward maybe transverse seam separating the mesonotum from the epi- more or less truncated; forming the keystone of the ante- notum. rior arch of the gastric mill. mesoepisternum see mesepisternum mesocephalic a. [Gr. mesos, middle; kephale, head] Having a medium size head. mesofacial plate see face mesocephalic pillars (ARTHRO: Insecta) In bees, two oblique mesofauna see mesobiota chitinous bars forming a brace between the anterior and mesofurca see furca posterior walls of the head. mesogastric lobe/area (ARTHRO: Crustacea) In Decapoda, mesocercaria n. [Gr. mesos, middle; kerkos, tail] (PLATY: the medial division of the gastric region of the carapace; Trematoda) A juvenile stage occurring in digenetic trema- usually five-sided in outline with a long narrow forward todes, an unencysted stage between the cercaria and the projection. metacercaria. mesogloea n. [Gr. mesos, middle; gloios, glutinous] A thin to mesocerebrum n. [Gr. mesos, middle; L. cerebrum, brain] very thick, acellular to rather cellular, gelatinous connective (ARTHRO: Crustacea) Ganglion of antennular somite; deu- tissue between the inner and the outer layers of a two-lay- terocerebrum. ered animal. mesocoel n. [Gr. mesos, middle; koilos, hollow] 1. The body mesohyl n. [Gr. mesos, middle; hyle, matter] (PORIF) The cavity of the second division of the deuterostome body. 2. space lying between the pinacoderm and the choanoderm. (BRYO) Assumed to be the cavity within and at the base of mesolamella n. [Gr. mesos, middle; L. dim. lamina, layer] A the tentacles. 3. (MOLL) Second or middle division of the thin mesogloeal layer between epidermis and gastrodermis coelom. in Cnidaria and Porifera. mesocole a. [Gr. mesos, middle; L. colere, to inhabit] Living mesolecithal egg Eggs with moderate yolk content. see cen- conditions with neither too much nor too little water. trolecithal egg. mesoconch n. [Gr. mesos, middle; konche, shell] (MOLL: Bi- mesology see ecology valvia) An intermediate stage in formation of the disso- conch; separated from other stages by pronounced discon- mesomere n. [Gr. mesos, middle; meros, part] 1. A blas- tinuities. tomere of medium size. 2. A mesoblastic somite. 3. Central zone of coelomic pouches in an embryo. 4. (ARTHRO: In- mesocuticle n. [Gr. mesos, middle; L. cutis, skin] A layer with secta) The inner divisions of the phallic lobes that unite to distinctive staining properties between the exocuticle and form the aedeagus (the intromittent organ). endocuticle. mesomerites n.pl. [Gr. mesos, middle; meros, part; -ites, mesoderm n. [Gr. mesos, middle; derma, skin] The cell layer having nature of] (ARTHRO: Diplopoda) Modified 9 pair of between ectoderm and endoderm in the embryonic cells of limbs; together with 8 pair (promerites) of limbs function- 553 554 Maggenti and Gardner On line Di ctio nar ing as pincers to pull out female vulvae. mesopleural suture (ARTHRy Oof: Insecta) The external groove of Inve mesomeron n. [Gr. mesos, middle; meros, thigh] (ARTHRO: the mesopleural ridge, betweenrttehbe base of the wing to the rate Insecta) In Diptera, the meron of the mesothorax behind midcoxal articulation. Zoo log the midcoxa below the mesepimeron. see metameron, mesopleuron n.; pl. -ra [Gr. mesos, middle; ypleuron, side] meron. (ARTHRO: Insecta) 1. The pleuron of the mesothorax; in meson n. [Gr. mesos, middle] The central plane; the midline of winged insects, composed of basalare, subalare, mesepis- the body; an imaginary plane dividing the body into right ternum, mesepimeron and mesotrochantin. 2. In Diptera, and left halves; the saggital plane. the dorsal part of the mesepisternum; area in front of the root of the wing between the noto- and sternopleural su- mesonephridium n. [Gr. mesos, middle; nephros, kidney] tures. Nephridium of mesodermal origin. mesopleurosternal ridge (ARTHRO: Insecta) In Diptera, a mesonotum n. [Gr. mesos, middle; notos, back] (ARTHRO: In- large, posteriorly curved invagination of the mesopleuros- secta) The back or upper side of the mesothorax. ternal suture. mesopelagic a. [Gr. mesos, middle; pelagos, sea] Pertaining mesopleurosternal suture (ARTHRO: Insecta) In Diptera, the to the pelagic zone of intermediate depth of 200-1000 m; external groove between the meskatepisternum and the between the epipelagic and bathypelagic zones. mesobasisternum, or mesosternum when the mesobasis- mesopeltidium see schizopeltid ternum is not distinguishable; the pleurosternal suture. mesophragma n. [Gr. mesos, middle; phragma, fence] (AR- mesopleurum n. [Gr. mesos, middle; pleuron, side] (ARTHRO: THRO: Insecta) A chitinous piece that descends into the in- Insecta) In Hymenoptera Ichneumonidae, the mesepister- terior of an insect body with the postscutellum as the base. num. mesoplankton n. [Gr. mesos, middle; plankton, wandering] mesopostnotum n. [Gr. mesos, middle; L. post, after; Gr. Floating life below euphotic zone; plankton organisms re- notos, back] (ARTHRO: Insecta) The postnotum of the tained by a plankton net. mesothorax. see metapostnotum. mesoplax n. [Gr. mesos, middle; plax, plate] (MOLL: Bivalvia) mesopostscutellum n. [Gr. mesos, middle; L. post, after; A calcareous transverse plate straddling the two valves on scutellum, small shield] (ARTHRO: Insecta) The postscutel- their dorsal margins. see protoplax, metaplax. lum of an insect's mesothorax. mesopleural bristles (ARTHRO: Insecta) In Diptera, a row of mesopraescutum n. [Gr. mesos, middle; L. prae, before; bristles on the posterior margin of the mesopleura. scutum, shield] (ARTHRO: Insecta) The praescutum of the mesopleural fovea (ARTHRO: Insecta) In Hymenoptera Ich- mesothorax. see prescutum. neumonidae, a pit or short horizontal groove on the meso- mesopsammic a. [Gr. mesos, middle; psammos, sand] Per- pleurum, anterior to the mesopleural suture and below the taining to organisms living interstitially in sand or a mate- speculum. rial in the form of rounded grains; psammous. mesop- mesopleural ridge (ARTHRO: Insecta) In Diptera, the pleural sammon n. see sabulous. ridge marked externally by the mesopleural suture, be- mesopseudogyne see pseudogyne tween pleural apophyseal pit above the midcoxal articula- mesorhabdions n.pl. [Gr. mesos, middle; dim. rhabdos, rod] tion to the base of the wing. (NEMATA) The walls of the mesostome. see rhabdion. mesopleural sulcus (ARTHRO: Insecta) In Diptera, passing mesoscutellum n. [Gr. mesos, middle; L. scutellum, little downwards from the wing base to the middle coxa. 555 556 Maggenti and Gardner On line Di ctio nar shield] (ARTHRO: Insecta) The scutellum of the mesothorax, mentum and the articulaymofentum in certain more highly de- Inv usually referred to as scutellum. veloped living species. erte bra te Z mesoscutum n. [Gr. mesos, middle; L. scutum, shield] (AR- mesotarsal ring see basitarsal ring ool ogy THRO: Insecta) The scutum of the mesothorax. mesotarsus n. [Gr. mesos, middle; tarsos, sole of foot] (AR- mesoseries n. [Gr. mesos, middle; L. series, row] (ARTHRO: THRO: Insecta) The tarsus of the middle leg. Insecta) In larva, a band of crochets or hooks extending mesotergum see mesonotum longitudinally on the mesal side of a proleg; when curved, varying from a quadrant to slightly more than a semicircle mesothoracotheca n. [Gr. mesos, middle; thorax, chest; in extent, seldom exceeding two-thirds of a circle. theke, case) (ARTHRO: Insecta) In pupal forms, the cover- ing of the mesothorax. mesosoma n. [Gr. mesos, middle; soma, body] 1. The middle part of an invertebrate's body. 2. (ARTHRO: Chelicerata) In mesothorax n. [Gr. mesos, middle; thorax, chest] (ARTHRO: Arachnida, the anterior portion of the abdomen, often Insecta) The middle of the thoracic divisions. clearly set off from the metasoma. 3. (ARTHRO: Insecta) mesothyridid n. [Gr. mesos, middle; thyridos, a window] For Hymenoptera, see alitrunk. 4. (POGON) The short (BRACHIO) Pedicle opening partly in the ventral umbo and frenular region of the body. partly in the delthyrium, with beak ridges appearing to bi- mesosome n. [Gr. mesos, middle; soma, body] (ARTHRO: sect the opening. Crustacea) A collective term for all free thoracic somites mesotriaene n. [Gr. mesos, middle; triaina, trident] (PORIF) A behind the head. megasclere triaene with a rhabd projecting on both sides of mesospermalege n. [Gr. mesos, middle; sperma, seed; L. a cladome. legere, to gather] (ARTHRO: Insecta) A special pouch in mesotroch n. [Gr. mesos, middle; trochos, wheel] (ANN: Poly- certain females for reception of sperm; Ribaga's or Ber- chaeta) A ciliated band around the midbody of a marine lese's organ. annelid. mesosternal cavity (ARTHRO: Insecta) In Elateridae, the Mesozoa, mesozoans n.; n.pl. [Gr. mesos, middle; zoon, opening into which the prosternal process catches. animal] Ciliated, multicellular organisms, endoparasitic in a mesosternellum n. [Gr. mesos, middle; L. dim. sternum, variety of marine invertebrates; two layered, having no breast bone] (ARTHRO: Insecta) A small rod-like plate that skeletal, muscular, nervous, digestive, respiratory, or ex- articulates posteriorly with the mesosternum. cretory elements. mesosternum n. [Gr. mesos, middle; sternon, breast] 1. (AR- mesozona n. [Gr. mesos, middle; zone, belt] (ARTHRO: In- THRO: Crustacea) In some Decapoda Brachyura, the me- secta) The middle portion of the pronotum. see prozona. dian plate of the sternum. 2. (ARTHRO: Insecta) In Hymen- metabiosis n. [Gr. meta, between; bios, life] A condition of life optera, the ventral part of the mesothorax; between the where an organism precedes and prepares the environment fore and mid-coxae. for another organism, inducing an exchange of growth mesostome, mesostom n. [Gr. mesos, middle; stoma, factors beneficial among species. mouth] (NEMATA) A division of the protostome preceded metablastic see ectoderm anteriorly by the prostome and posteriorly by the metas- metabola n. [Gr. metabole, change] (ARTHRO: Insecta) Species tome. see prostome. having distinct external changes during the stages of their mesostracum n. [Gr. mesos, middle; ostrakon, shell] (MOLL: life history. see paurometabola, hemimetabola, Polyplacorphora) A calcareous shell layer between the teg- holometabola. 557 558 Maggenti and Gardner On line Di ctio nar metabolic activities Any forms of activity that have to do with zoa) Secondary mesentayroiefs between the primary cycle. Inv metabolism. erte metacoel n. [Gr. meta, after; koilos,bhraollow] 1. The body cav- te Z metabolic water Water produced in the cells as a by-product ity of the third division of the deutoeorol stome body. 2. ogy of metabolism. (BRYO) Believed to be the main body cavity. metabolism n. [Gr. metabole, change; ismos, denoting condi- metacorporal valve (NEMATA) An expanded, strongly cuticu- tion] The sum total of chemical reactions occurring in living larized portion of the triradiate lumen at the center of the matter. metabolic a. see catabolism, anabolism. metacorpus that functions as a pump during feeding. metabolite n. [Gr. metabole, change; ites, like] Any by-prod- metacorpus n. [Gr. meta, after; L. corpus, body] (NEMATA) uct of a living organism; a metabolized substance. The median esophageal bulb; the middle bulb; the median metabranchial lobe or area (ARTHRO: Crustacean) In Deca- bulb. poda, the posterior branchial region of the carapace. metacoxal plate (ARTHRO: Insecta) In Coccinellidae, a portion metacentric a. [Gr. meta, after; kentron, center of circle] of the first ventral segment included above the ventral Having the centromere situated along the chromosome, lines, visible on the metathorax. except at or near the tip, e.g., J- or V-shaped in meta- metacyclic a. [Gr. meta, after; kyklos, circle] Pertaining to a phase. see telocentric, acrocentric. stage in the life cycle of a parasite that is infective to its metacephalon n. [Gr. meta, after; kephale, head] (ARTHRO: definitive host. Insecta) In Diptera, the area behind the mouth extending metacyst n. [Gr. meta, after; kystis, bladder] A cystic stage of up toward the neck. a parasite in a host. metacercaria n. [Gr. meta, after; keros, tail] (PLATY: Trema- metaepisternum see metepisternum toda) The stage succeeding the cercarial, following loss of metaerucism n. [Gr. meta, after; L. eruca, caterpillar] (AR- tail; it may invade the definitive host (blood flukes) or may THRO: Insecta) Poisoning by larval setae on cocoons, etc. become encysted and await passive transfer to that host. see lepidopterism. metacerebrum n. [Gr. meta, after; L. cerebrum, brain] (AR- metafemale n. [Gr. meta, after; L. femella, little woman] (AR- THRO: Crustacea) Ganglion of antennal somite; tritocere- THRO: Insecta) In Diptera, an individual with 3 X-chromo- brum. somes and 2 sets of autosomes; found in Drosophila. metacestode n. [Gr. meta, after; kestos, girdle; eidos, form] metagastric lobe or area (ARTHRO: Crustacea) In Decapoda, (PLATY: Cestoda) The developmental stage of the plero- the posterior division of the gastric region of the carapace; cestoid where proglottids are evident but generative organs sometimes ill-defined. are not fully mature. metagenesis n. [Gr. meta, after; genesis, beginning] Alterna- metachemogenesis n. [Gr. meta, change of; chemeia, infu- tion of sexual and asexual reproduction in the life cycle of sion; genesis, beginning] (ARTHRO: Insecta) In holome- certain animals; alternation of generations. see hetero- tabolous forms, post-emergence biochemical maturation; genesis. does not include sexual maturation. metagnath n. [Gr. meta, change of; gnathos, jaw] (ARTHRO: metachromasia, metachromasis, metachromasy n. [Gr. Insecta) Those insects with biting mandibles when young meta, change of; chroma, color] Staining of tissue compo- and sucking mouth parts as adults. see menognath, Me- nents in different colors by a single dye. norhyncha. metacnemes n.pl. [Gr. meta, after; kneme, leg] (CNID: Antho- metagonia n. [Gr. meta, after; gonia, angle] (ARTHRO: In- 559 560 Maggenti and Gardner On line Di ctio nar secta) The anal angle of a wing. metaneme n. [Gr. meta, ayftoefr; nema, thread] (NEMATA) Fila- Inve metagynous a. [Gr. meta, after; gyne, female] (ANN: Oli- mentous organs in or near the rltaetberal epidermal cords that rate gochaeta) Having the ovaries only in segment xiii or a ho- usually have anterior and sometimesZopoosterior filaments log moeotic segment. and a central scapulus; thought to be streytch receptors. see orthometaneme, propriocepter. metagyny see protandry metanephridium n.; pl. -ia [Gr. meta, after; nephros, kidney] metakinesis n. [Gr. meta, after; kinesis, movement] Separa- Paired osmoregulatory or excretory tubules in some phyla; tion of chromatids during anaphase. tubules that open into the body cavity and are found in metamale n. [Gr. meta, change of; L. mas, male] (ARTHRO: coelomate animals. Insecta) A male Drosophila with three (3) sets of auto- metanephromixium n. [Gr. meta, after; nephros, kidney; somes and one X-chromosome. mixis, mingling] (ANN: Polychaeta) Nephromixium in which metamere n. [Gr. meta, after; meros, part] One or more of a the coelomostome and nephrostome are combined into a series of homologous parts of many animals; a merosome; genital and/or excretory duct. see mixonephridium. a somite. metameric a. metanotal gland (ARTHRO: Insecta) In male Oecanthus (Or- metameric sac see osmeterium thoptera) and some blattids, special glands on the dorsum metamerism n. [Gr. meta, after; meros, part] Segmental of the thorax that produces a secretion attractive to fe- repetition of homologous body parts; metameres; me- males. tasomes. metanotal slopes (ARTHRO: Insecta) In Diptera, the pleuro- metameron n. [Gr. meta, after; meros, upper thigh] (ARTHRO: tergites. Insecta) In Diptera, the meron of the metathorax; a verti- metanotum n.; pl. -nota [Gr. meta, after; notos, back] (AR- cal sclerite above the hindcoxa. see mesomeron, meron. THRO: Insecta) The dorsal sclerite of the metathorax. metameros n. [Gr. meta, after; meros, part] (ARTHRO: In- metanotal a. secta) In Lepidoptera, the combined sixth to eighth ab- metaparapteron n. [Gr. meta, after; para, beside; pteron, dominal segments. wing] (ARTHRO: Insecta) In Formicidae, the postscutellum. metamorphosis n.; pl. -ses [Gr. meta, change of; morphe, metapeltidium see schizopeltid form] A marked change in form or structure an animal un- metaphase n. [Gr. meta, after; phasis, to appear] The stage dergoes from one growth stage to another; also applies to of mitosis when the chromosomes line up in the equatorial the actual process of changing from larval to adult form. plane of the spindle. see anamorphosis, epimorphosis, hypermetamorpho- sis. metaplasis n. [Gr. meta, after; plasis, molding] The mature period in an individuals life. metanauplius n. [Gr. meta, after; nauplios, shellfish] (AR- THRO: Crustacea) One to several larval stages subsequent metaplasm n. [Gr. meta, after; plasma, formed or molded] to the first (nauplius) larva; characterized by increasing Non-living protoplasmic inclusions. metaplastic a. size and the appearance of additional appendages. metaplax n. [Gr. meta, after; plax, plate] (MOLL: Bivalvia) A metandry n. [Gr. meta, after; aner, male] (ANN) Possessing long narrow posteriorly pointed, rounded or forked acces- only the posterior pair of testes; in earthworms, testes re- sory plate covering the gape between the two valves on the stricted to segment xi. metandric a. see proandry, dorsal margins posterior to the umbo. see protoplax, holandry. mesoplax. 561 562 Maggenti and Gardner On line Di ctio nar metapleural bristles (ARTHRO: Insecta) In Diptera, a bristle or see mesopostnotum. y of Inv bristles on the metapleura. erte metapostscutellum see postscutellburma te Z metapleural gland (ARTHRO: Insecta) In most Formicidae, a ool metapraescutum, metaprescutum n. [Gr.ogmy eta, after; L. gland with an external bulla and a small orifice, opening on prae, before; scutum, shield] The prescutum of the each side of the metathorax at its lower posterior corners; metathorax. thought to function as a protection against microorganisms in the nest chamber due to fungistatic and bacteriostatic metapygidium n. [Gr. meta, after; pyge, rump] (ARTHRO: In- activity. secta) 1. In Dermaptera, the posterior ventral segment of the supra-anal plate. 2. In Coleoptera, the penultimate ter- metapleuron n.; pl. -ura [Gr. meta, after; pleuron, side] (AR- gite when the elytra are shorter than the abdomen. THRO: Insecta) 1. The lateral sclerites of the metathorax. 2. In Diptera, the pleuron of the metathorax. metapleural a. metarhabdions n.pl. [Gr. meta, after; rhabdos, rod] (NEMATA) The cuticularized walls of the metastome. see rhabdion. metapleurum n. [Gr. meta, after; pleuron, side] (ARTHRO: In- secta) In Hymenoptera Ichneumonidae, ordinarily divided metascolex n. [Gr. meta, after; scolex, worm] (PLATY: into two parts, the lower is largest and generally referred Cestoda) The posterior portion of a transversely divided to; the lower part an oval or subtriangular area on the side scolex. of the thorax, between middle and hind coxae to the pro- metascutellum n. [Gr. meta, after; L. scutellum, dim. scutum, podeum; the upper area lies behind the upper half of the shield] (ARTHRO: Insecta) The scutellum of the metathorax. mesepimeron and below and behind the base of the hind metasoma n. [Gr. meta, after; soma, body] 1. The posterior wing, separated from the propodeum by a suture. region of many invertebrates. 2. (ACANTHO) The posterior metapneustic a. [Gr. meta, after; pneustikos, of breathing] part of the body or trunk. 3. (ARTHRO) The abdomen or (ARTHRO: Insecta) Said of aquatic insect larvae having only urosome. 4. (ARTHRO: Chelicerata) In Arachnida, the ab- the posterior pair of spiracles open and functioning. see dominal body segments and telson; posterior part of opist- oligopneustic. hosoma. 5. (ARTHRO: Crustacea) see metasome. 6. metapodeon n. [Gr. meta, after; podeon, neck] (ARTHRO: In- (PHORON) The long gonadal region following the secta) That part of an abdomen behind the podeon or peti- mesosoma, and bearing external papillae and chitinous at- ole. tachment structures. see opisthosoma. metapodium n. [Gr. meta, after; pous, foot] (MOLL) The pos- metasome n. [Gr. meta, after; soma, body] (ARTHRO: Crusta- terior portion of the foot. cea) In Copepoda, a portion of the prosome, consisting of free thoracic somites anterior to the major point of body metapodosoma n. [Gr. meta, after; pous, foot; soma, body] flexion; or first three abdominal somites; metasoma. (ARTHRO: Chelicerata) In ticks or mites, that portion of the podosoma that bears the third and fourth pair of legs. metastasis n.; pl. -ses [Gr. meta, after; stasis, standing] The transfer of pathogenic microorganisms to parts of the body metapolar cells (MESO) The posterior tier of cells in the ca- remote from the origin of infection. lotte. metasternal glands (ARTHRO: Insecta) In Formicidae, paired metapon n. [Gr. metopon, forehead] (ARTHRO: Crustacea) In organs in the posterior area of the thorax, opening to the Decapoda, the entire preoral area, including part of the outside near the pleural-sternal margins of the metathorax. mandibular somite. metasternal orifice (ARTHRO: Insecta) In Formicidae, the metapostnotum n. [Gr. meta, after; L. post, after; Gr. notos, opening of the metasternal gland. back] (ARTHRO: Insecta) The postnotum of the metathorax. 563 564 Maggenti and Gardner On line Di ctio nar metasternum n. [Gr. meta, after; sternon, chest] (ARTHRO: secta) In Hemiptera, spyinofose or triangular process of the Inv Insecta) 1. The sternum or ventral sclerite of the metasternum. erte bra metathorax. 2. For Diptera, see mesepimeron. te Z Metazoa, metazoans n.; n.pl. [Gr. meta, aofotler; zoon, animal] ogy metastigmata n.pl. [Gr. meta, after; stigma, point] (ARTHRO: 1. A small phylum of endoparasitic, ciliated, multicellular Insecta) The posterior spiracles of the synthorax. organisms composed of two layers, lacking skeletal, mus- metastome, metastom n. [Gr. meta, after; stoma, mouth] cular, nervous, digestive, respiratory or excretory ele- (NEMATA) The posterior subdivision of a prostome. ments. 2. Often regarded as degenerate flatworms ap- pended to phylum Platyhelminthes. metazoic a. metastoma n.; pl. -mata [Gr. meta, after; stoma, mouth] 1. (ARTHRO: Crustacea) The lower lip posterior to the mandi- metazoea n. [Gr. meta, after; zoe, life] (ARTHRO: Crustacea) A bles, usually cleft into paragnaths; hypostoma; hypostome; late zoeal stage in Anomura and Brachyura with simple hypopharynx; labium. 2. (ARTHRO: Insecta) In Orthropera, uniramous limbs on posterior thoracomeres, budding pleo- the hypopharynx. pods 1-5 at the same time, and having stalked eyes. metasyndesis see acrosyndesis metazona n. [Gr. meta, after; zone, belt] (ARTHRO: Insecta) The posterior part of the pronotum. see prozona. metatarsus n.; pl. -si [Gr. meta, after; tarsos, flat of the foot] (ARTHRO) The basal segment of a tarsus; next to the tibia; metazonite n. [Gr. meta, after; zone, belt] (ARTHRO: Diplo- the basitarsis. poda)The posterior portion of a diplosomite, divided by a transverse groove. see prozonite. metatentorium n.; pl. -ia [Gr. meta, after; L. tentorium, tent] (ARTHRO: Insecta) A posterior arm of the tentorium. metecdysis n. [Gr. meta, after; ekdysis, molt] (ARTHRO) The period following a molt before the new cuticle hardens, es- metatergum see metanotum pecially in Decapoda (Crustacea). metathetely n. [Gr. meta, after; theein, to run; telos, end] metelattosis n. [Gr. meta, after; elatton, smaller] (ARTHRO: (ARTHRO) 1. A neotenous adult arthropod after undergoing Chelicerata) Regression of postembryonic development, normal or more than normal numbers of molts. 2. In In- initiated after the beginning stasis. secta, often resulting in failure to develop wings, or form- ing brachypterous adults. metenchium n. [L. meta, conical column; Gr. enchos, spear] (NEMATA: Secernentea) Conus of the stylet in plant para- metathoracotheca n. [Gr. meta, after; thorax, chest; theke, sites in the order Tylenchida. see telenchium. case] (ARTHRO: Insecta) The pupal covering of the metathorax. metenteron n. [Gr. meta, after; enteron, intestine] (CNID) The radial digestive chamber. see mesenteron. metathorax n. [Gr. meta, after; thorax, chest] (ARTHRO: In- secta) The third or posterior segment of the thorax, bear- metepimeron n.; pl. -mera [Gr. meta, after; epi, on; meros, ing the hind legs and the hind wings. part] (ARTHRO: Insecta) The epimeron of the metathorax. metatroch n. [Gr. meta, after; trochos, wheel] (ANN) In Poly- metepisternum n.; pl. -sterna [Gr. meta, after; epi, on; ster- chaeta, trochophore larvae, as well as some other groups, non, breast] (ARTHRO: Insecta) 1. The episternum of the the postoral girdle of cilia. see prototroch, telotroch. metathorax. 2. In Culicidae, behind and below the metathoracic spiracle. metatrochophore n. [Gr. meta, after; trochos, wheel; phorein, to bear] (ANN: Polychaeta) A ciliated trochophore meter n. [Gr. metron, a measure] A measure of length in the larva developing trunk segments. metric system; 39.37 inches. see centimeter, millimeter. metaxyphus n. [Gr. meta, after; xiphos, sword] (ARTHRO: In- metinfraepisternum n. [Gr. meta, after; L. infra, underneath; 565 566 Maggenti and Gardner On line Di ctio nar Gr. epi, on; sternon, breast] (ARTHRO: Insecta) In Odonata, microbody n. [Gr. mikrosy, ofsmall; Eng. body] Spherical or Inv a ventral subdivision of the metepisternum. ovoid bodies that are rich in eenrtzeymes of peroxide metabo- bra lism. te Z metochy see symphily, synechthry ool ogy metoecious parasite A parasite that is not host-specific. see microbotroph n. [Gr. mikros, small; bios, life; trophein, to heteroecious. feed] Microscopic faunal forms that obtain nourishment from digesting living microorganisms; microbivorous. metope n. [Gr. metopon, forehead] The middle frontal portion of a head. see metapon. microcalthrop, microcaltrop n. [Gr. mikros, small; ML. calci- trapa, a four-pointed weapon] (PORIF) A microsclere metopic suture see coronal suture or branch tetraxon spicule with four rays, one elongated and three metopidium n. [Gr. metopidios, of the forehead] (ARTHRO: In- short; a euaster with 4 persistent rays. secta) In Membracidae, the anterior downward sloping microcentrum see centrosome surface of the prothorax. microcephalic a. [Gr. mikros, small; kephale, head] Having an metraterm n. [Gr. metra, womb; terma, end] (PLATY: Trema- abnormally small head. see megacephalic, meso- toda) In Digenea, the muscular, terminal portion of the cephalic. uterus. microcercous cercaria (PLATY: Trematoda) Small cercaria metric system A decimal system of measures and weights. with a very short tail and a stylet in the oral sucker. see metrocyte n. [Gr. metros, mother; kytos, container] A cell xiphidiocercaria. having given rise to other cells by division; mother cell; microchaetae n.pl. [Gr. mikros, small; chaeta, mane] Small precursory cell. bristles. see chaeta, macrochaetae. micelle n.; pl. -ae [L. micarius, crumbs] A supermolecular microclimate n. [Gr. mikros, small; klima, slope] The climate colloid particle, often an orderly packet of chain molecules of the habitat in which the individual lives. in parallel arrangement. microcnemes n.pl. [Gr. mikros, small; knemis, leg] (CNID: micraesthetes n.pl. [Gr. mikros, small; aisthetes, one who Anthozoa) In Actinaria, younger, narrow mesentaries lack- perceives] (MOLL: Polyplacophora) One or more small sen- ing filaments. see macrocnemes. sory organs, in the form of eyes, sometimes accompanying the megaesthetes. see aesthete. microcotylate cercaria (PLATY: Trematoda) A group of small xiphidiocercariae with a postequatorial ventral sucker, and micraner n. [Gr. mikros, small; aner, male] (ARTHRO: Insecta) finless tail equal to the body length. In Formicidae, a dwarf male. see microgyne. microdrile n. [Gr. mikros, small; drilos, worm] (ANN: Oli- micrergate n. [Gr. mikros, small; ergate, worker] (ARTHRO: gochaeta) A general term for the aquatic forms. see Insecta) In Formicidae, a dwarf worker, a microergate. megadrile. microbe n. [Gr. mikros, small; bios, life] A microscopic organ- microelectrode n. [Gr. mikros, small; elektron, amber] Small ism. electrode for sensing electrical activity in a neuron. microbiota n. [Gr. mikros, small; bios, life] 1. The combined microergate see micrergate or singularly considered microflora and microfauna of an organism. 2. Microscopic soil organisms. microevolution n. [Gr. mikros, small; L. evolutus, unrolling] All processes of species formation and differentiation microbivorous a. [Gr. mikros, small; bios, life; L. vorare, to brought about by the combined action of various evolution- devour] Microbe eating; microbiotrophic. ary factors. see macroevolution. 567 568 Maggenti and Gardner On line Di ctio nar microfauna n. [Gr. mikros, small; L. Faunus, diety of herds the animal pole in eggs ywoitfh abundant yolk. Inve and fields] Very small animals; animals less than 200 m. micromesentary n. [Gr. mikros, rtsemb all; mesos, middle; en- rate microfibril n. [Gr. mikros, small; L. dim. fibra, fiber] Micro- teron, gut] (CNID: Anthozoa) In ZoantZhoaoria, an incomplete log scopic or submicroscopic fiber. secondary mesentary. y microfilaria n. [Gr. mikros, small; L. filum, thread] (NEMATA) micrometer n. [Gr. mikros, small; metron, a measure] A unit The uncoiled mobile embryo of a filaria, that either escapes of microscopic measure, designated by the Greek letters from the egg shell (unsheathed) or causes stretching of the m; one-thousandth of a millimeter. shell into an elongated sac accommodated to the uncoiled micromillimeter see nanometer embryo (sheathed). micromutation see point mutation microgamete n. [Gr. micros, small; gametes, husband] 1. A slender, active, male anisogamete. 2. Derived from the mi- micron see micrometer crogametocyte of the malarial protozoan. see macrogam- micronekton n. [Gr. mikron, small; nektos, swimming] Small, ete. swimming organisms in the ocean. microgametocyte n. [Gr. mikros, small; gamete, husband; micronephridia see microic, nephridium kytos, container] The male gametocyte that gives rise to microniscus, micronicus see epicaridum microgametes. micronucleocytes see plasmatocytes microgeographic race A local race, restricted to a small area. microorganism n. [Gr. mikros, small; organon, instrument] A microgram n. [Gr. mikros, small; gramma, small weight] One microscopic organism such as most nematodes, rotifers, thousandth of a gram. etc. microgranular cells (PORIF) Cells with cytoplasm charged with micropaleontology n. [Gr. mikros, small; palaios, ancient; small dense granules. logos, discourse] The study of microscopic fossils. microgyne n. [Gr. mikros, small; gyne, woman] (ARTHRO: In- microphagous a. [Gr. mikros, small; phagein, to eat] Feeding secta) In Formicidae, a dwarf female. see micraner. on small objects. see macrophagous. microhabitat n. [Gr. mikros; small; L. habitare, to dwell] A microphthalmy n. [Gr. mikros, small; ophthalmos, eye] An small or restricted habitat. see niche. abnormally small antenna. microphthalmic a. microhexactine n. [Gr. mikros, small; hex, six; aktis, ray] microplankton n. [Gr. mikros, small; plankton, wandering] (PORIF) A small hexactine spicule. Small organisms floating in water. microic a. [Gr. mikros, small; eidos, like] (ANN: Oligochaeta) microplasmatocyte n. [Gr. mikros, small; plasmatos, image; Smaller than macroic, a substitute for micronephridial, of- kytos, container] (ARTHRO: Insecta) A small plasmatocyte ten applied to nephridia as large as or larger than megan- having a small amount of vacuolar cytoplasm. see eo- ephridia. plasmatocyte. microlecithal a. [Gr. mikros, small; lekithos, egg yolk] Con- micropore n. [Gr. mikros, small; poros, pore] (MOLL: Polypla- taining little yolk. cophora) A small pore in the dorsal plates; associated with microleucocyte n. [Gr. mikros, small; leukos, white; kytos, an aesthete. container] A small amoebocyte. micropredator n. [Gr. mikros, small; L. praedator, plunderer] micromere n. [Gr. mikros, small; meros, part] Small cells of A temporary parasite. 569 570 Maggenti and Gardner On line Di ctio nar micropseudogyne see pseudogyne microsomites n.pl. [Gr. miykroofs, small; soma, body] (ARTHRO: Inv Insecta) In embryology, smalel rtseecondary rings or somites micropterism, microptery n. [Gr. mikros, small; pteron, bra of the macrosomites later to becometeboZdy segments. wing] Small wings. ool ogy micropterogyne n. [Gr. mikros, small; pteron, wing; gyne, microspecies n.pl. [Gr. mikros, small; L. species, a kind] A woman] (ARTHRO: Insecta) A female with small wings. small local species population that shows little variability; jordanon. micropterous a. [Gr. mikros, small; pteron, wing] Having small or vestigial wings. microspines n.pl. [Gr. mikros, small; L. spina, thorn] (AR- THRO: Insecta) In some larvae, minute spines on the exte- micropyle n. [Gr. mikros, small; pyle, entrance] A pore in the rior body wall. investing membrane of an egg through which a spermato- zoan enters for fertilization. micropylar a. microstome n. [Gr. mikros, small; stoma, mouth] A small opening or orifice. micropyle apparatus (ARTHRO: Insecta) Raised structures around the micropyle of an egg. microsymbiote n. [Gr. mikros, small; symbiosis, life together] A term designating the smaller organism, or microorgan- micropyrenic a. [Gr. mikros, small; pyren, kernel] Having nu- ism, of a symbiotic association. clei smaller than average for a particular cell type of an in- dividual or species. microthorax n. [Gr. mikros, small; thorax, chest] (ARTHRO: Insecta) The neck or cervix, when the cervix is a reduced microsclere n. [Gr. mikros, small; skleros, hard] (PORIF) A body segment. packing or reinforcing spicule, usually of a size, and ornate shape that occur strewn throughout the mesenchyme. see microthrix n.; pl. microtrices [Gr. mikros, small; thrix, hair] megasclere. (PLATY: Cestoda) One of the minute folds of the tegument that aid in absorption of nutrients. microscolecin, microscolecine n. [Gr. mikros, small; skolex, worm] (ANN: Oligochaeta) Provided with a pair of tubular microtome n. [Gr. mikros, small; temnein, to cut] Instrument prostates opening to the exterior in segment xvii along side for cutting thin sections of tissues for microscopic exami- of, or together with, the sperm ducts. nation. microscopic a. [Gr. mikros, small; skopein, to view] Being in- microtomy n. [Gr. mikros, small; temnein, to cut] The science visible with the naked eye, usually requiring the aid of a of cutting and staining of thin sections of tissues for micro- microscope for elucidation of structure or recognition of scopic examination. whatever characters are involved. see macroscopic. microtrichia n.pl.; sing. -ium [Gr. mikros, small; thrix, hair] microsensillum n. [Gr. mikros, small; L. sensillus, sensitive] 1. (ARTHRO: Insecta) Minute, abundant, non-articulate hairs Small sensillum or sensory puncture. found on the wings (aculeae). see macrotrichia. 2. (PLATY: Cestoda) see microthrix. microseptum n. [Gr. mikros, small; L. septum, partition] (CNID: Anthozoa) A Zoantharia with incomplete or imper- microtubules n.pl. [Gr. mikros, small; L. tubulus, small water fect mesentary. pipe] Minute tubules in cells that are often cross-linked; found in cilia, spindle fibers, and in the cytoplasm where microsomes n. [Gr. mikros, small; soma, body] Formerly any they form the cytoskeleton. small granules in the cytoplasm; fragments of endoplasmic reticulum. microtype n. [Gr. mikros, small; typos, type] (CNID: Antho- zoa) A normal mesentery arrangement. see macrotype. microsomia n. [Gr. mikros, small; soma, body] Dwarfishness; nanism. microvillus n.; pl. -villi [Gr. mikros, small; L. villus, shaggy 571 572 Maggenti and Gardner On line Di ctio nar hair] Minute processes on the inner surface of epithelial migrante n. [L. migrator,y owfanderer] (ARTHRO: Insecta) In Inve cells. see brush border. aphids, the winged, parthenogrteenbetic, viviparous females rate microxea n. [Gr. mikros, small; oxys, sharp] (PORIF) A micro- that develop on the primary host, thenZofloy to the secondary log sclere similar to an oxea, but very small. host. see alienicola, fundatrix. y microzoon n. [Gr. mikros, small; zoon, animal] A microscopic migration n. [L. migratus, change habitat] The act or instance animal. of any form of invertebrate that moves from the place of birth for food or other purposes. migrational a. mictic egg Eggs that have undergone meiosis and are there- fore haploid; when unfertilized they produce haploid males. milk gland (ARTHRO: Insecta) Specialized accessory gland of see amictic egg. Glossina and the Pupipara that produces a milk containing lipids, proteins and amino acids. micton n. [Gr. mictos, mixed] Widely distributed species pro- duced by interspecific hybridization which are fully fertile millepunctatus a. [L. mille, a thousand; punctum, prick] Cov- with parent species. ered or studded with many dots, points, or minute depres- sions. mid-axis n. (MOLL: Bivalvia) Straight line in commissural plane at a right angle to the hinge axis and beginning at the mid- millimeter n. [L. mille, a thousand; Gr. metron, a measure] point of the ventral margin of the resilifer. One-thousandth of a meter, or 0.03937 of an inch; mm. midbody n. [A.S. middel, middle; bodig, body] The equatorial millimicron see nanometer region of the body. mimesis see mimicry middle bulb see metacorpus mimetic a. [Gr. mimikos, initative] Characterized by mimicry. middle cuticular layer (NEMATA) Formerly used for the matrix mimetic polymorphism Polymorphism in which the various layer of the cuticle. morphs resemble other species distasteful or dangerous to middle field see discoidal area a predator; often restricted to females. middle plate (ARTHRO: Insecta) In embryology, that area be- mimic n. [Gr. mimos, actor] 1. An organism that resembles tween the mesodermal rudiment and the lateral ectodermal another in color, habit or structure for the purpose of pro- plates. tection. 2. Nonallelic genes with similar phenotypic effects. middorsal a. [A.S. middel, middle; L. dorsum, back] Pertaining mimicry n. [Gr. mimikos, imitative] The resemblance in color to the true dorsal line of an individual; dorsomedian. or structure to other species that are distasteful or poison- ous to a predator. see Batesian and Mullerian mimicry. midgut n. [A.S. middel, middle; gut] The mesenteron; the middle portion of the alimentary tract. mines n. [Celtic origin] (ARTHRO: Insecta) Larval galleries or burrows on the inside of leaf tissue. midgut gland (MOLL) A lobed or unlobed gland, of a compound tubular or acinous nature, opening into the gut in one or minim n. [L. minimus, least] 1. A very small object. 2. 1/60 of more places; sometimes called liver. a fluid dram or 0.06 ml. 3. (ARTHRO: Insecta) In Formici- dae, a minor worker. midintestine see midgut minor worker (ARTHRO: Insecta) An individual belonging to midventral a. [A.S. middel, middle; L. venter, belly] Pertaining the smallest worker subcaste, esp. in Formicidae; a minim. to the true ventral line; ventromedian. see media worker, major worker. midventral glands see supplementary organs minute a. [L. minutus, small] 1. Very small. 2. (ARTHRO: In- 573 574 Maggenti and Gardner On line Di ctio nar secta) A few millimeters in length or less. organ having both excreytoorfy and genital functions. Inv erte miolecithal a. [Gr. meion, less; lekithos, egg yolk] Referring to mixoploidy n. [Gr. mixis, minglingb;raaploos, onefold; eidos, te Z eggs containing little yolk. like] Having cells with different chromoooslome numbers in ogy miracidium n.; pl. -dia [Gr. dim. meirakion, young girl] cell populations. (PLATY: Trematoda) In Digenea, the first larval stage; a mnemotaxis n. [Gr. mneme, memory; taxis, arrangement] ciliated, free-swimming form. Movements in which memory plays a part. mirror n. [L. miror, to look at] (ARTHRO: Insecta) In Hemiptera mode n. [L. modus, measure] The most frequent value of any Cicadidae, clear cuticular membrane located near the measurable characteristic in a population. stridulatory apparatus; specular membrane. modifer genes Genes that affect the phenotypic expression of missense mutation Gene mutation in which one amino acid is genes at other loci. changed; the altered proteins may show some activity. modification n. [L. modus, measure; facare, to make] Any mitochondria n.pl.; sing. mitochondrion [Gr. mitos, thread; variation caused by non-genetic factors. chondros, grain] Sausage-shaped structures in the cyto- modioliform a. [L. modiolus, a small measure or drinking ves- plasm of animal and plant cells. sel; forma, form] 1. In the form of a nave or hub of a mitogen n. [Gr. mitos, thread; genos, birth] An agent that wheel; more or less globular with truncated ends. 2. (MOLL: stimulates a cell to undergo mitosis. Bivalvia) Beaks are not terminal and anteroventral region mitosis n.; pl. -ses [Gr. mitos, thread] The division and sepa- forms a slight bulge; shell shaped like the genus modiolus . ration of chromosomes during cell division, involving the modulation n. [L. modulare, to measure] 1. Alteration in cells longitudinal splitting of each chromosome resulting in two by environment without change in their basic character. 2. equal sets of daughter chromosomes. mitotic a. Interactive modification of cells during development. mitosome n. [Gr. mitos, thread; soma, body] A body arising moiety n.; pl. -ties [L. medius, the middle] 1. One of two from the spindle fibers of the preceding mitosis; spindle equal parts. 2. An indefinite portion. remnant. mola n. [L. mola, mill] (ARTHRO: Insecta) In Coleoptera, the mitraria larva (ANN: Polychaeta) Post-trochophore larva of thickened and enlarged basal part of the internal ridge of Owenia with three hypertrophied setae for defense or floa- the mandible used for grinding. see molar lobe. tation. molar a. [L. mola, mill] 1. Adapted for grinding. 2. (ARTHRO: mixed nerve A nerve with both motor and sensory fibers. Crustacea) Pertaining to the grinding surface on the inner mixed nest (ARTHRO: Insecta) A nest inhabited by two or more edge of the mandibles or jaws. species of social insects with intermingling between adults molar lobe (ARTHRO: Insecta) The proximal lobe of the mandi- and broods. see compound nest. bles used for chewing or grinding. see mola. mixocoel n. [Gr. mixis, mingling; koilos, hollow] (ARTHRO) The molar process (ARTHRO: Crustacea) The grinding portion of adult body cavity (not a true coelom) derived from a blas- the gnathal lobe of the mandible; pars molaris. tocoel and secondary body cavities that functions as a molecular biology The study of biological phenomena in hemocoel. terms of the physiochemical properties of molecules in a mixonephridium n. [Gr. mixis, mingling; nephros, kidney] cell. (ANN: Polychaeta) A type of nephromixium in which the molecular genetics The study of genetics at the level of mole- nephridium and coelomoduct are combined into a single 575 576 Maggenti and Gardner On line Di ctio nar cules. number instead of two nyuocflei. Inve molecules n.pl. [L. dim. moles, mass] The small particles into monaulic a. [Gr. monos, one; aulorste,bpipe] (MOLL: Gastropoda) rate which any substance can be divided without chemical Male and female portions with a comZmooon gonopore. see log change. diaulic, triaulic. y Mollusca n.; pl. mollusks, molluscs [L. molluscus, soft] A monaxon n. [Gr. monos, one; axon, axis] (PORIF) Spicules phylum of invertebrates with a soft unsegmented body and formed by growth in one or both directions along a single usually covered with a double or single shell, or having an axis. monaxonid a. internal shell; includes snails, chitons, tusk shells, bivalves, monecious see monoecious limpets, squids, octopi, etc. monila n. [L. monile, necklace] (BRYO) Concentric thickening of molluscicide n. [L. molluscus, soft; caedere, to kill] An agent the zooecial wall causing a beadlike appearance. that kills snails. monilicorn see moniliform molt, moult n. [L. mutare, to change] The periodic process of loosening and discarding the cuticle, accompanied by the moniliform a. [L. monile, necklace; forma, shape] Beadlike; formation of a new cuticla in the process of growth; may be resembling a string of beads; contracted or jointed at divided into two distinct processes: apolysis and ecdysis. regular intervals. see pharate. moniliform glands (NEMATA) Beadlike cells around the uvette molting fluid 1. Often undetermined fluid that causes the of the demanian system, usually forming a rosette. loosening of the old cuticle. 2. (ARTHRO: Insecta) A fluid monoallelic a. [Gr. monos, one; allelon, one another] Refer- containing chitinase and proteinase that digests the ring to a polyploid in which all alleles at a locus are identi- unsclerotised cuticle (except the ecdysial membrane). cal. molting hormone see ecdysone monobasic a. [Gr. monos, one; basis, step] Describing genera moltinism n. [L. mutare, to change] Polymorphs of differing originally based on one species only. strains or biotypes that undergo a different number of lar- monocentric a. [Gr. monos, one; kentron, point] Pertaining to val molts. a chromosome with one centromere. molula n. [L. dim. mola, mill] (ARTHRO) The dicondylic joint by monochromatic a. [Gr. monos, one; chromos, color] Of one which the tibia articulates with the femur. color only; unicolored. monacanthid a. [Gr. monos, one; acantha, thorn] (ECHINOD: monocondylar see monocondylic Asteroidea) Having one row of ambulacral spines. monocondylic a. [Gr. monos, one; kondylos, knuckle] Having monactinal a. [Gr. monos, one; aktis, ray] (PORIF) Spicule de- one condyle. velopment originating from a fixed point in one direction monocondylic joint A joint with a single point of articulation only. between segments. monaene a. [Gr. monos, one; triaina, trident] (PORIF) A modi- monocrepid a. [Gr. monos, one; krepis, base] (PORIF) Per- fied tetraxon with only one clad. taining to a desma formed on a monaxon. monarsenous a. [Gr. monos, one; arsen, masculine] Polyga- monocule n. [Gr. monos, single; L. oculus, eye] (ARTHRO) A mous; having one male to numerous females. one-eyed animal, as certain crustaceans and insects. monaster n. [Gr. monos, one; aster, star] A unipolar spindle monocyclic a. [Gr. monos, one; kyklos, circle] (ECHINOD: Cri- that results in a nucleus with an unreduced chromosome 577 578 Maggenti and Gardner On line Di ctio nar noidea) Refers to calyx plates of primitive stalked crinoids monogenic a. [Gr. monos,yoonfe; genesis, beginning] 1. Mono- Inve having an aboral cycle of 5 plates (basal) and 5 plates (ra- genetic. 2. Reproducing in onlyrtoenbe way. 3. Determined by rate dial) oral to the basal plates. the alleles of a single gene. see polygeZnooic. 4. Monomeric. log monodactyl, monodactyle, monodactylous a. [Gr. monos, monogeny n. [Gr. monos, one; genos, offspringy] The produc- one; dactylos, finger] (ARTHRO) Pertaining to an append- tion of offspring of one sex by arrhenogenesis or thely- age, ambulacrum or claw with only one unguis. see genesis. bidactyl. monogonoporus a. [Gr. monos, single; gonos, offspring; po- monodelphic a. [Gr. monos, one; delphys, womb] (NEMATA) ros, channel] Having both male and female gonads opening Having one uterus. through a common orifice. monodesmatic a. [Gr. monos, one; desmos, tendon] (AR- monogony n. [Gr. monos, one; gonos, offspring] Asexual re- THRO: Chelicerata) Pertaining to an articulation between production. two segments of an appendage with one tendon inserted at monograph n. [Gr. monos, one; graphos, a writing] An ac- the base of the distal segment. count or description of one subject or class of subjects; a monodisk, monodisc n. [Gr. monos, one; diskos, disc] (CNID: treatise discussing a single subject in detail. Scyphozoa) One ephyra developed and released at a time monogyny n. [Gr. monos, one; gyne, woman] (ARTHRO: In- before another forms by transverse fission. see polydisk, secta) The existence of only one functional queen in a nest. strobilization. see polygyny. monodomous a. [Gr. monos, one; doma, house] (ARTHRO: In- monohybrid n. [Gr. monos, one; L. hybrida, mongrel] The off- secta) Having one nest per colony. see polydomous. spring of parents differing in one character. monoecious a. [Gr. monos, one; oikos, house] Having two monolayer n. [Gr. monos, one; Eng. layer] A single layer of kinds of gametes produced by the same individual; her- cells growing on a substrate. maphrodite; ambisexual. monoecism n. see dioecious. monomers n.pl. [Gr. monos, one; meros, part] Simple com- monoembryony n. [Gr. monos, one; embryon, fetus] The pounds from which polymers are synthesized. production of only one embryo from a fertilized ovum or egg. monomeri n.pl., sing. -us [Gr. monos, one; meros, part] (AR- THRO: Insecta) Insects with one-jointed tarsi. monogamy n. [Gr. monos, one; gamos, marriage] The condi- tion of having only one mate. monogamous a. see polyg- monomeric a. [Gr. monos, one; meros, part] 1. Pertaining to amy. a single segment. 2. Derived from one part. 3. Monogenic. monogenesis n. [Gr. monos, one; genesis, beginning] 1. The monomerosomatous a. [Gr. monos, one; meros, part; soma, development of life from a single entity or cell. 2. Asexual body] Having all body segments fused. reproduction. 3. Direct development without metamorpho- monomerous a. [Gr. monos, one; meros, part] Having only sis. one joint or part. monogenetic a. [Gr. monos, one; genesis, beginning] 1. Per- monometrosis see haplometrosis taining to monogenesis. 2. Designates parasites with a monomial a. [Gr. monos, one; L. nomen, name] Having one simple direct life cycle that is completed in one host. 3. name or designation consisting of one term only; unino- Producing offspring of one sex by arrhenogenesis or thely- mial. see binomial. genesis. monomorphic colony (BRYO) A colony in which only one kind 579 580 Maggenti and Gardner On line Di ctio nar of zooid occurs in the zone of asexual reproduction. mostly extinct, with a limy pofet-like, cap-shaped, cone-shaped Inv or spoon-shaped shell with sereiartlely paired muscle scars. monomorphic polypides (BRYO: Phylactolaemata) One mor- bra te Z phologic type of organ system in an asexual budding zone. monoploid a. [Gr. monoploos, onefold] 1. oAonl y somatic cell or ogy monomorphic zooids (BRYO: Gymnolaemata) Zooids of one individual with one set of chromosomes. 2. Having the ba- morphologic type in the zone of astrogenetic repetition. sic number of chromosomes in a polyploid series. see euploid, aneuploid. monomorphism n. [Gr. monos, one; morphe, form] 1. A population that exhibits a single form. see polymorphism. monoplont see haplont 2. Species that contain only the female sex. see dimor- monorchic a. [Gr. monos, one; orchis, testicle] Having one phism. 3. (ARTHRO: Insecta) In social insects, having testis. see diorchic. within a species or colony only a single worker subcaste. monosiphonous a. [Gr. monos, one; siphon, tube] (CNID: Hy- monomorphic a. drozoa) Having a single central tube as in the hydrocaulus. monomyarian a. [Gr. monos, one; mys, muscle] 1. Having monosome n. [Gr. monos, one; soma, body] 1. A chromo- only one muscle. 2. (MOLL: Bivalvia) In oysters and scal- some lacking an allele. see polysome. 2. A single ribo- lops, pertaining to the anterior adductor muscle that has some bound to messenger RNA. completely disappeared, and the posterior adductor shifted to a more central location between the valves; mon- monosomic a. [Gr. monos, one; soma, body] Lacking one omyarian condition. see anisomyarian. chromosome of a normal complement (somatic number is 2N-l). mononchoid a. [ Mononchus; Gr. eidos, like] (NEMATA: Adeno- phorea) Having the characteristics of the predacious monospermy n. [Gr. monos, one; sperma, seed] One sperm nematode genus Mononchus. fertilizing an ovum; normal fertilization of an ovum. mononychous a. [Gr. monos, single; onyx, claw] Pertains to monostich n. [Gr. monos, one; stichos, row] 1. Cells arranged organisms having a single or uncleft claw. in a row along one side of an axis. 2. (NEMATA: Adenopho- rea) Esophagi in Stichosomida (=Trichocephalida; Mer- monoparental a. [Gr. monos, one; L. parens, progenitor] With mithida) in which the cells are external to the esophagus females only. and along one side. monostichous a. see distich. monophagous a. [Gr. monos, one; phagein, to eat] Adapted monostigmatous a. [Gr. monos, single; stigma, mark] Having to subsist on a single kind of food; specialized on a single one stigma only. host species; monotrophic. see polyphagous, oligo- phagous. monostome n. [Gr. monos, one; stoma, mouth] (PLATY: Tre- matoda) A fluke lacking a ventral sucker. monophyletic a. [Gr. monos, single; phyle, tribe] 1. With a single common ancestry. 2. Any group whose most recent monostome cercaria (PLATY: Trematoda) A cercaria with a common ancestor is cladistically a member of that group. muscular oral sucker anteriorly and no ventral sucker; en- see polyphyletic, oligophyletic. cysts on objects in water. monophyly see monophyletic monothalamous a. [Gr. monos, one; thalamos, chamber] Unilocular; single chambered. see monothecal. monoplacid a. [Gr. monos, one; plax, flat plate] Having only one plate. monothecal a. [Gr. monos, one; theke, case] 1. Having one chamber or loculus. see monothalamous. 2. (ANN: Poly- Monoplacophora, monoplacophorans n., n.pl. [Gr. monos, chaeta) Having only one spermatheca. see polythecal. one; plax, flat plate; pherein, to carry] A class of Mollusca 581 582 Maggenti and Gardner On line Di ctio nar monothely n. [Gr. monos, one; thelys, woman] Polyandry, monticolous a. [L. mons, my ofuntain; colare, to inhabit] Living Inve with one female being fertilized by many males. mono- in mountains. rteb rate thelious a. monticule n. [L. dim. mons, mountain] (BZoRoYO: Stenolaemata) log monothetic a. [Gr. monos, one; tithenai, to place] Pertaining A prominence on the colony surface made yby a cluster of to taxa based on only one or a few characters. see poly- polymorphs. see macula. thetic. morgan n. [named for T. H. Morgan] A chromosome map unit; monotrochous a. [Gr. monos, one; trochous, wheel] (ARTHRO) expresses the relative distance between genes on a chro- Having the trochanter composed of a single piece. mosome, as determined by crossing-over phenomena. monotrophic see monophagous moribund a. [L. mors, death] Dying; near death. monotropic a. [Gr. monos, one; tropikos, a turning] 1. Turn- morph n. [Gr. morphe, form] Any of the individual variants of ing in one direction. 2. (ARTHRO: Insecta) Visiting only one a polymorphic population. kind of flower for nectar. see polytropic. morpha n. [Gr. morphe, form] (ARTHRO: Insecta) A word end- monotype n. [Gr. monos, one; typos, type] A holotype of a ing recently incorporated in Hemiptera indicating major species based on a single specimen. groups; Nepomorpha (=Hydrocorisae). monotypic a. [Gr. monos, one; typos, type] Pertains to a morphallaxis n. [Gr. morphe, form; allaxis, exchange] A re- taxon containing only one immediate subordinate taxon, as generative process in which the new parts are reorganized a genus containing only one species, or a species contain- from the old, instead of being formed anterior or posterior ing only one subspecies. to the level of amputation. monovalent articulation Articulation permitting movement in morphism see polymorphism one mode only; forward and backward, but not up and morphogenesis n. [Gr. morphe, form; genesis, beginning] down, etc. The development of the characteristic form and structure of monovarial a. [Gr. monos, one; L. ovum, egg; arium, pro- a cell or an organism. ducing organ] Having one ovary. morphology n. [Gr. morphe, form; logos, discourse] The sci- monovoltine see univoltine ence of structural characteristics, particularly those on the monoxenic a. [Gr. monos, one; xenos, guest] Pertaining to surface of the body. morphological a. the rearing of an organism with only one know species as a morphometrics n. [Gr. morphe, form; metron, measurement] food source. see axenic. Body measurements. monoxenous a. [Gr. monos, one; xenos, guest] Living within morphometry n. [Gr. morphe, form; metron, measurement] a single host during a parasite's life cycle. see dixenous. Measurement of external form. monozoic a. [Gr. monos, one; zoon, animal] (PLATY: Cestoda) morphopathology n. [Gr. morphe, form; pathos, suffering; Non-strobilated cestodes. logos, discourse] The branch of pathology dealing with the monozonian a. [Gr. monos, one; zone, girdle] (ARTHRO: Dip- morbid changes occurring in the structure of tissues, cells lopoda) Having a cylindrical sclerite composed of fused ter- and organs. gites, pleurites and sternites. morphosis n. [Gr. morphosis, a shaping] Nonadaptive and un- montane a. [L. mons, mountain] Pertaining to mountains and stable variation in an individual's morphogenesis associated coniferous forests of mountains. with environmental changes. 583 584 Maggenti and Gardner On line Di ctio nar morphospecies n.pl. [Gr. morphe, form; L. species, kind] A entirely within the bodyyofthat transmits stimuli from the Inv typological species based on morphological differences. see central nervous system to the emrtoetor elements of the body. bra phenon. te Z motor neurocyte The neurocyte of a motoroonleuron. ogy morphotype n. [Gr. morphe, form; L. typos, type] The type motor neuron A neuron that transmits excitation directly to an specimen of one of the forms of a dimorphic species. effector; motor nerve. morula n. [L. dim. morus, mulberry] In embryology, consisting mottled a. [F. mattele, curdled] Spotted with different colors; of a cluster of cleaving blastomeres; stage preceding blas- maculated; blotched. tula. moult see molt morular cell (BRYO) A cell filled with refringent spheres in the peritoneal membrane and funicular strand. mound nest (ARTHRO) Nest or part of one built above ground of soil or carton material. morular organ see columella mouse unit (MOLL: Bivalvia) A unit of measurement employed morulation n. [L. dim. morus, mulberry] Formation of the as a gradient of shellfish poisoning. morula during holoblastic egg cleavage. mouth n. [A.S. muth, mouth] The oral aperture. morulit see nucleolus mouth-anus axis (MOLL: Bivalvia) In oysters, a line through mosaic n. [Gr. Mousaios, of the Muses] 1. An organism com- the mouth and anus. posed of two or more cell lines of different genetic or chromosomal constitution, both cell lines being derived mouth capsule see buccal cavity from the same zygote; genetic mosaic. see chimera. 2. An mouth cirri (ARTHRO: Crustacea) In Cirripedia, the first pair of individual displaying characteristics of more than one sex modified cirri. or polymorphic form; phenotypic mosaic. mouth cone (ARTHRO: Insecta) The rostrum; proboscis, mosaic evolution Evolution that involves differential rates for prostomium. different structures, organs, or other components of the mouth fork see lacinia phenotype. mouth hooks (ARTHRO: Insecta) In Cyclorrhapha 2nd instars, mosaic theory (ARTHRO) The theory explaining the function of cuticular claw-like structures, one on each side of the atrial the compound eye, with the numerous ommatidia receiving opening, thought to articulate with a small ventral sclerite a portion of the image and then combining them into a to- that may represent the maxillary cardo; mandibular tal image in the brain. sclerites. moschate a. [L. moschus, musk] Having an odor similar to mouth spear see stomatostyle, odontostyle musk. movable finger (ARTHRO: Crustacea) The dactyl of the chela. mother cell A precursory cell or metrocyte. movable hook (ARTHRO: Insecta) In Odonata, a small tooth on mother genus An original genus from which others have de- the inner border of the lateral lobe slightly external to the rived by nomenclatorial division. end-hook. motile a. [L. movere, to move] Capable of spontaneous mucid a. [L. mucidus, mucus-like] Mouldy; slimy. movement. mucific a. [L. mucus, mucus; facere, to make] Pertains to mu- motor nerve see motor neuron cus-secreting. motor nervous system A part of the nervous system lying mucigen n. [L. mucus, mucus; genos, to produce] A substance 585 586 Maggenti and Gardner On line Di ctio nar from which mucin is derived in mucin secreting cells. Mullerian mimicry Similariytyof(usually consisting of coloration) Inv of several species that are disetartseteful, poisonous, or other- mucilaginous a. [L. mucus, mucus] Pertaining to gum-like or bra wise harmful to a predator. see BatetseiZan mimicry. mucilage. ool ogy mucin n. [L. mucus, mucus] A glycoprotein secreted by various Muller's larva (PLATY: Turbellaria) In Polycladida, larva pos- cells or glands. sessing eight posteriorly directed postoral lobes. see cephalotrocha larva. mucivorous a. [L. mucus, mucus; vorare, to devour] Feeding on the juices of plants. mucivore n. Muller's organ (ARTHRO: Insecta) A group of numerous scolopophores forming a swelling; in Acridoidea, applied to mucoid a. [L. mucus, mucus; Gr. eidos, like] Glycoproteins the inner surface of each tympanum and connected by the that are found in cartilage, cuticle, etc. auditory nerve to the metathoracic ganglion. mucolytic a. [L. mucus, mucus; lysis, loosen] The breaking Muller's thread see ovarial ligament down or dissolving of mucus. multiangular, multiangulate a. [L. multus, many; angulus, mucopolysaccharides n.pl. [L. mucus, mucus; Gr. polys, angle] Having many angles. many; sakcharon, sugar] Polysaccharides with aminosugar and uronic acid; a constituent of glycoproteins. multiarticulate a. [L. multus, many; articulus, joint] Many- jointed; polyarthric. mucoprotein a. [L. mucus, mucus; Gr. protos, first; eidos, form] A glucoprotein containing more than 4% hexosa- multicamerate a. [L. multus, many; camera, chamber] Having mine. see glucoprotein, glycoprotein. multiple chambers. see multilocular. mucoreous a. [L. mucor, mould] Pertaining to or appearing multicarinate a. [L. multus, many; carina, keel] Having many mouldy; surface covered with small fringe-like processes. ridges or carinae. mucosa n. [L. mucus, mucus] Mucus membrane; lining of in- multicellular a. [L. multus, many; cella, cell] Comprised of ternal passageways. two or more cells; many-celled. mucous a. [L. mucus, mucus] Secreting mucus or a similar multicolonial n. [L. multus, many; colonia, colony] (ARTHRO: sticky substance by various cells, glands, or membranes. Insecta) Population of social insects divided into independ- ent colonies or nests. mucous membrane see mucosa multifactorial a. [L. multus, many; facere, to do] Controlled mucro n.; pl. mucrones [L. mucro, sharp point] A small by several gene loci. pointed projection, or spine-like ending on a terminus. mucronate a. multifarious a. [L. multifarius, manifold] Arranged in several rows. see polystichous. mucron see mucro multifid a. [L. multus, many; findere, to cleave] Having many mucronate valve see beak divisions or clefts. mucus n. [L. mucus, mucus] A slimy fluid secreted by gland multiforous a. [L. multus, many; foris, gate] (ARTHRO: In- cells present in many epithelia known as mucous mem- secta) A spiracle with three or more secondary openings in branes. or near the peritreme. mulberry corpuscle see spherule cell multilocular a. [L. multus, many; loculus, little place] Many Mullerian association A group of species showing Mullerian celled or chambered; having many divisions or compart- mimicry. ments; plurilocular. see multicamerate. 587 588 Maggenti and Gardner On line Di ctio nar multilocular hydatid cyst see alveolar hydatid cyst multiserial crochets (ARTHy RoOf : Insecta) In Lepidoptera, cro- Inv chets arranged in several rowse.rte multinucleate a. [L. multus, many; nucleus, kernel] Pertaining bra te Z to cells with many nuclei; a coenocyte; polykaric. multisetiferous a. [L. multus, many; setoao,l bristle; ferre, to ogy multiordinal crochets (ARTHRO: Insecta) Crochets of larvae bear] With many setae. when they arise from a single row, but with many alter- multispinose a. [L. multus, many; spina, spine] With many nating lengths. see ordinal. spines. multiovulate a. [L. multus, many; dim. ovum, egg] With multispiral a. [L. multus, many; spira, a coil] With numerous many ovules. whorls. multiparasitism n. [L. multus, many; Gr. para, near; sitos, multistriate a. [L. multus, many; stria, furrow] With many food] The coincident parasitism of an organism by two or striations; numerous thread-like lines, grooves or more parasites of different species. scratches. multiparous a. [L. multus, many; parere, to beget] Bearing multivalent a. [L. multus, many; valens, strong] Pertaining to many offspring. several chromosomes being attached together. multipartite a. [L. multus, many; partitis, divided] Divided multivalved a. [L. multus, many; valva, leaf of a folding door] into many parts. (MOLL: Polyplacophora) Having more than two sections. multiple allele A series of three or more alternative forms of a multivincular a. [L. multus, many; vinculum, to bind] (MOLL: gene at a single locus in a chromosome. Bivalvia) Having a ligament with many bonds of union. multiplicate a. [L. multus, many; plicare, to fold] Having multivoltine a. [L. multus, many; It. volta, time] Having two many folds or plicae. or more generations or broods in a year or season. see multipolar cell Cells with more than two nerves preceding bivoltine. from it. multizooidal bud see giant bud multiporous septulum (BRYO: Gymnolaemata) A membrane mumia n. [ML. mumia, mummy] (ARTHRO: Insecta) A pupa. or plate with many holes; a rosette-plate. mumia pseudonympha (ARTHRO: Insecta) A pupa with some multiramous a. [L. multus, many; ramus, branch] Many degree of locomotion. branched. munite a. [L. munitus, fortify] Provided with armature. multiramous plasmatocyte A plasmatocyte with three spin- mural lacuna see pustula dle ends. mural plate see compartmental plate multiramous vermiform cell A vermiform cell with three spindle ends. mural spine (BRYO: Stenolaemata) A small skeletal spine ex- tending into the zooidal chamber. multiserial a. [L. multus, many; series, a row] Having many series or rows. mural tooth (NEMATA) A tooth attached to, or derived from the stomatal wall. multiserial bands (ARTHRO: Insecta) In Lepidoptera, caterpil- lars with crochets absent from the mesial and lateral parts muricate a. [L. murex, a pointed stone] Formed with sharp of the circle. elevated points; covered with sharp points. multiserial circle (ARTHRO: Insecta) In Lepidoptera, caterpillar muscidiform larva (ARTHRO: Insecta) Like a Diptera larva; crochets arranged in three or more concentric circles. sub-cylindrical larva with the cephalic-end pointed and the 589 590 Maggenti and Gardner On line Di ctio nar caudal-end broad. the lateral cords, extenydoinfg posteriorly and becoming tri- Inv furcate at the base of the lateerratle rays; possibly functioning muscle n. [L. musculus, muscle] Tissue made up of specialized bra to extend the bursa. te Z cells for the production of motion by contraction; a sheet, ool ogy bundle, or mass of such tissue. musculus costerum lateralium internis (NEMATA: Se- muscle fibers see fibroplasm cernentea) Bursa muscle that arises as paired submedian muscles at the body wall anterior to the intestino-rectal muscle layer(s) 1. One or more layers of muscle below the valve; each laterally extended branch entering the root of epithelium. 2. (BRYO: Phylactolaemata) Both longitudinal the lateral ray; possibly functioning to bend the bursa in- and circular muscles between epithelial and peritoneal lay- wards. ers of the colony wall. mushroom bodies (ARTHRO: Insecta) The two stalked nerve muscle scar A mark on the interior of valve or carapace in structures of the protocerebrum, that are connected with Crustacea, Mollusca and Brachiopoda representing the po- the optic lobes. see corpora pedunculata. sition of muscle attachment, recognizable by surface tex- ture, elevation, depression or a delimiting narrow groove; a mushroom gland (ARTHRO: Insecta) Large mushroom-shaped muscle imprint. seminal vesicles. muscle segment A myomere. mutafacient n. [L. mutatus, change; facere, to make] Gene or genetic element that causes or increases the chance of muscularis n. [L. musculus, muscle] (ARTHRO: Insecta) A mutation at another site. muscular sheath surrounding the alimentary canal. mutagen n. [L. mutare, to change; Gr. gennaein, to produce] muscular pad (ECHI) A muscular tissue pad or pads associated Any physical or chemical agent that increases mutational with the ventral setae. events. muscular sheath (ARTHRO: Insecta) In Culicidae, a sheath en- mutant n. [L. mutare, to change] An organism that undergoes closing a coelomic section of each of the ventral setae. mutation. musculature n. [L. musculus, muscle] The system or ar- mutation n. [L. mutare, to change] A structural change in a rangement of muscular structure of an organism. gene, consisting of a replacement, duplication, or deletion musculus bursae basalis (NEMATA: Secernentea) Bursal mus- of one or several pairs in the DNA. cle that arises from the ventral side of the bursa and ex- mutation frequency The frequency of mutants in a popula- tends dorsally to the root of the dorsal ray. tion. musculus costae dorsalis (NEMATA: Secernentea) A many mutationism see De Vriesianism branched bursal muscle that arises mediodorsally in the dorsal ray, and extending anteriorly to become trifurcate, mutation rate Frequency with which a mutation occurs per then the median arm splits into four parts. site per generation. musculus costae lateralis externus anterior (NEMATA: Se- mutation theory A theory of the origin of new characteristics cernentea) Bursal muscles that arise anterior to the mus- in organisms as a result of changes in the genes. see sal- culus costae lateralis externus posterior, extending posteri- tation. orly to the base of the ventral rays; possibly functioning to mutator genes Any gene that causes an increase in mutation extend the bursa. rates in other genes. see mutafacient. musculus costae lateralis externus posterior (NEMATA: Se- mutein n. [L. mutatus, change; Eng. protein] A mutationally cernentea) A bursal muscle that arises anteriorly dorsad of altered protein analogous to the normal type. 591 592 Maggenti and Gardner On line Di ctio nar mutic, mutilous a. [L. muticus; shortened] Unarmed; lacking mycotoxin n. [Gr. mykes, fyuonfgus; toxikon, poison] A low mo- Inve defensive processes that usually occur. lecular weight metabolite of frutnebgi which is poisonous to rate mutilate v.t. [L. mutilus, cut-off] To deprive of one or more animals. Zoo log essential part(s); to amputate. myelin sheath A fatty material surrounding a neyrve fiber. muton n. [L. mutare, to change] The smallest element in the myiasis n. [Gr. myia, fly; -iasis, morbid condition] A condition array of mutation sites, that when altered, may give rise to deriving from invasion by dipterous larvae. a mutant. myoblast n. [Gr. mys, muscle; blastos, bud] A cell that pro- mutualism n. [L. mutuus, reciprocal] A type of symbiosis in duces muscular fiber. which both host and symbiont benefit from the association. myochordotonal organ (ARTHRO: Crustacea) In Decapoda, a muzzle n. [OF. musel, snout] Snout. proprioceptor at the proximal end of the meropodite, a flat myarian a. [Gr. mys, muscle] 1. Referring to muscle, as in membrane lying between the skeleton and sheath of the meromyarian. 2. (MOLL: Bivalvia) Used in classification as accessory flexor muscle of the carpus, with distal bipolar to number and position of the adductor muscles. sensory cells passing through the membrane and attached to the skeleton; having scolopidia similar to the insect mycelium n. [Gr. mykes, fungus] In fungi, the network of chordotonal organs. filaments that form the vegetative part. myocytes n.pl. [Gr. mys, muscle; kytos, container] (PORIF) mycetangium n. [Gr. mykes, fungus; angeion, vessel] (AR- Cells that cause contraction. THRO: Insecta) The fungus-storing organs of Platypodinae, a sac-like invagination of the epidermis at the posterior myoepithelial n. [Gr. mys, muscle; epi, upon; thele, nipple] 1. part of the prothorax. (BRYO) A contractile ectodermal cell with intracellular stri- ated muscles. 2. (CNID) Epithelium with a longitudinal con- mycetocyte n. [Gr. mykes, fungus; kytos, container] A large, tractile fiber at the base; epitheliomuscular. polyploid cell containing intracellular mutualistic and com- mensalistic microsymbiotes; one of many cells that make myofibrillae, myofibrils n.pl; sing. -a [Gr. mys, muscle; dim. up the mycetome. see symbiosis. fibra, fiber] Longitudinal fibrils of muscle cells. mycetome n. [Gr. mykes, fungus; -oma, mass] A specialized myogenic a. [Gr. mys, muscle; gennaein, to produce] Pertains structure or organ that houses symbiotes. to a muscle contraction initiated by nerve impulse. see neurogenic. mycetometochy n. [Gr. mykes, fungus; metochos, sharing] (ARTHRO: Insecta) Symbiosis between fungi and the dwell- myoglobin n. [Gr. mys, muscle; L. globus, ball] A type of he- ers of compound nests. moglobin occurring in muscle cells concerned with oxygen transport and storage; also called myohemoglobin. mycetophagous a. [Gr. mykes, fungus; phagein, to eat] Feeding on fungi; mycophagous; fungivorous. myohematin, myohaematin n. [Gr. mys, muscle; haima, blood] An iron pigment said to occur in muscles; thought to mycohelminths n.pl. [Gr. mykes, fungus; helmins, worm] be a cytochrome. Fungivorous nematodes. myoid a. [Gr. mys, muscle; eidos, like] Composed of muscle mycophagous a. [Gr. mykes, fungus; phagein, to eat] Feeding fibers. on fungi; mycetophagous; fungivorous. myology n. [Gr. mys, muscle; logos, discourse] That branch of mycosis n. [Gr. mykes, fungus; -sis, process of] Any disease anatomy dealing with the arrangement of muscles. caused by the invasion of fungi. myomere n. [Gr. mys, muscle; meros, part] A muscular segment. 593 594 Maggenti and Gardner On line Di ctio nar myoneural junction Point of junction between a motor nerve Feeding on ants. y of Inv and the muscle which it activates. erte myrmecophile n. [Gr. myrmex, ant;brpahilos, love] A symbiont te Z myoneure n. [Gr. mys, muscle; neuron, nerve] A motor neu- of ants. ool ogy ron. myrmecophilous a. [Gr. myrmex, ant; philos, love] Fondness myonicity n. [Gr. mys, muscle] The contracting power of mus- of, or benefited by an association with ants. see myrme- cle tissue. cole. myophore n. [Gr. mys, muscle; pherein, to bear] (MOLL: Bi- myrmecophily n. [Gr. myrmex, ant; philos, love] (ARTHRO: valvia) A spoon- or sickle-shaped structure beneath the Insecta) The utilization by other insects, mainly beetles, of beak on the interior of the shell; functioning as a place of ant colonies as domiciles and sources of food; ant symbio- attachment for certain muscles. sis. myrmecophilous a. myoplasm n. [Gr. mys, muscle; plasma, formed or molded] myrmecophobic a. [Gr. myrmex, ant; phobeisthai, to flee] The contractile portion of a muscle cell. Having the ability to repel ants. myosin n. [Gr. mys, muscle] Muscle protein that combines myrmecophyte n. [Gr. myrmex, ant; phyton, plant] A myrme- with actin to form actomyosin in muscle contraction. cophilous plant that has an obligatory, mutualistic relation- myostracum n. [Gr. mys, muscle; ostrakon, shell] (MOLL: Bi- ship with ants. valvia) That part of the shell wall secreted at the attach- myrmecoxenes n.pl. [Gr. myrmex, ant; xenos, guest] True ment of the adductor muscles. guests of ants. see symphile. myotasis n. [Gr. mys, muscle; tasis, tension] Muscular tonicity mysis stage (ARTHRO: Crustacea) In Decapoda, a larval stage or tension. in which only the thoracopods are used in swimming and myotome n. [Gr. mys, muscle; tome, to cut] A muscle seg- the compound eye is stalked; schizopod larva. see zoea. ment, somite or myomere. mystacine a. [Gr. mystax, moustache] Bearded; having tactile myrmecobiosis n. [Gr. myrmex, ant; biosis, life] A symbiotic hairs or vibrissae. relationship between ants; consociation. mystax n. [Gr. mystax, moustache] (ARTHRO: Insecta) A clus- myrmecochory n. [Gr. myrmex, ant; chorein, to spread] Ac- ter of hairs or bristles above the mouth; beard. tive dispersion of seeds by ants. mytiliform a. [L. mytilus, sea mussel; forma, shape] 1. (AR- myrmecoclepty n. [Gr. myrmex, ant; kleptes, thief] (ARTHRO: THRO: Insecta) In aquatic Hemiptera, the shell-shaped Insecta) A form of symbiosis in which the guest ant steals swimming feet. 2. (MOLL: Bivalvia) Having the form of a food from the host ant. mussel shell; mytiloid; shell shaped like the genus Mytilus. myrmecodomatium n.; pl. -ia [Gr. myrmex, ant; domos, myzesis n. [Gr. myzein, to suck] Suction or sucking. house] A plant tissue cavity inhabited by ants. myzorhynchus n. [Gr. myzein, to suck; rhynchos, snout] myrmecole n. [Gr. myrmex, ant; L. colere, to inhabit] An or- (PLATY: Cestoda) In some Tetraphyllidea, an apical stalked, ganism that lives in ants' nests, but does not otherwise in- sucker-like organ on the scolex. teract with them. see myrmecophilous. myrmecology n. [Gr. myrmex, ant; logos, discourse] The divi- sion of entomology that studies ants. Copyright ©2005 Armand R. Maggenti and Scott Gardner. myrmecophagous a. [Gr. myrmex, ant; phagein, to eat]