摘要:

Functional morphology and cirral activity are described for two species ofArmatobalanusand 15 species of pyrgomatine pyrgomatids in relation to their inhabitation of living scleractinian and hydrozoan corals. New details are given of the opercular anatomy ofMegatrema anglicum. Armatobalanus alliumandA. arcuatusabrade overgrowing coral coenosarc mechanically, using tergal beaks and cirri during cirral activity. Pyrgomatids erect an aperture frill (modified tergoscutal flaps). The frill is secretory and appears to be a source of chemical inhibition of coral overgrowth.Armatobalanus alliumperforms a strong pumping beat. Cirral activity inA. arcuatusis more varied and includes a faster dipping beat. Dipping beat is also characteristic of pyrgomatines. Opercular structure and function indicate thatArmatobalanus allium, A. arcuatus, Megatrema anglicumandCantellius euspinulosumform a functional evolutionary series, supporting the derivation of pyrgomatids fromArmatobalanus.Within the genusCantellius, a basic (type 1) and two modified (types 2 and 3) aperture frill mechanisms occur. Type 1 retains large tergal depressor muscles inserted on tergal wings on either side of the infolded aperture frill (C. euspinulosum, C. Septimus, C. gregarius). Type 2 is similar except that the muscle insertions are shifted mainly into the folds of the (larger) frill (C. pallidus, C. acutum). The type 3 frill is located more apically in a low operculum with reduced tergal depressor muscles and enlarged lateral scutal depressor muscles (C. secundus). More modified pyrgomatines can be variously derived from the three groups ofCantelliuson the basis of aperture frill mechanisms, cirral activities and differences in cirral morphology. The type 1 frill occurs inNobia projectum, N. conjugatumandPyrgoma cancellata.The type 2 frill is strongly developed inNobia grandis. Creusia spinulosaand four species ofSavigniumhave a type 3 frill. The cirral activities of species with frill types 1 and 2 are based on vertical dipping beat. Species with a type 3 frill have rostrocarinal dipping beat. InSavignium milleborumthis is fast beat, inS. elongatum, ‘normal’ beat, accompanied by carinal exhalent jets. Functional morphology thus reveals three main lines of evolution in the pyrgomatine pyrgomatids based on divergences withinCantellius.Each line has yielded specialized species with a fused wall and highly modified operculum, exemplified byPyrgoma cancellata(very reduced orifice).Nobia grandis(very large aperture frill) andSavignium milleporumandS. elongatum(double adductor scutorum).NobiaandSavigniumas previously defined are polyphyletic. Four new genera are proposed. The evolution of an aperture frill and chemical inhibition of coral overgrowth is associated with a reduced orifice and often a reduced cirral fan. In some species there may be nutrient uptake from the coral host, but experimental tests are nee

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1992.tb01249.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

In this paper I synthesize original and published studies of sperm transfer behaviour of 23 genera of water mites from 15 families. The morphology of spermatophores from 16 genera (12 families) is described. Behaviour and/or spermatophores are described for the first time for the following species:Hydrachna magniscutataMarshall,Hydrachna hesperiaLundblad,Hydrachnasp. nr.leegeiKoenike,Limnochares americanaLundblad,Limnesia undulata(Müller),Neumania distinctaMarshall,Unionicola(three species in theU. crassipes‐complex),Thyas slolliKoenike,Lebertia annaeHabeeb,Lebertiasp.,Pionasp. nr.debilis(Wolcott),Tiphys vernalis(Habeeb),Arrenurus dentipetiolatusMarshall,Arrenurus marshalliPiersig andArrenurus birgeiMarshall. On the basis of proximity of male and female during sperm transfer, I divide water mites into four groups: complete dissociation, involving no physical or chemical contact between the sexes (nine genera); incomplete dissociation, requiring distance‐or contact‐chemoreception but not involving pairing behaviour (five genera); pairing with indirect transfer, involving pairing behaviour with females controlling sperm uptake (three genera); pairing with direct transfer (=copulation), involving pairing behaviour and male placement of sperm in the receiving structure of the female (12 genera). Four genera have representative species in more than one category of sperm transfer. Factors possibly leading to the diversity of water mite mating behaviour include an evolutionarily flexible mode of sperm transfer in the ancestral water mite, and the development of planktonic and endoparasitic habits in many mites. Morphological features of spermatophores that improve physical stability, probability of females taking up sperm and resistance against osmotic stress are discussed. Finally, I present implications of mating behaviour and spermatophore morphology for phylogenetic relationships within water mites and between this group and terrestrial

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1992.tb01250.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY