DEFINITIONS OF EXTERNAL GENITAL STRUCTURES OF THE MALE The principal parts of the external genitalia and their commonly

developed accessories in male insects and other arthropods

may

be

named

and defined as given in the following list of terms, but no general nomenclature can be devised to include

names

for all the minor modifications and special developments found in the various orders ofinsects.

Aedeagus

(Aed).

— ^The

^distal part of the phallus

when

the latter has adififerentiatedbasalpart;usually the principal part of thephallus, or theentireorganifthephallobaseissuppressed;typicallyasclerotic tubewiththephallotremeatitsextremity.

Bursagenitalis

(GC). — ^The

^genital

^chamber

^{of eitherthemale or}

thefemale;inmaleinsectsa ventral invagination of the

membranous

integument behindtheninthabdominalsternumcontaining the phallus or phallicorgans.

Copidatory organs.

— ^Any

^structures used by ^eithersex for grasp- ingorholding the partnerduringmating, or particularly paired organs, usuallysegmentalappendages,speciallyadaptedor modified forcopu- latorypurposes.

Ductus ejaculatorius [Dej).

— ^The

^{median exit duct of the male}

genitalsystem; if

formed

bythe union of a pair of primary ductus ejaculatorii itis aductusconjunctus,ifdeveloped asasinglemedian invagination of the integument serving as an outlet for both vasa deferentiaitisaductuscommunis.

Ectophallus.

— The

outer wall orexposedpart of the phallusin dis- tinction tothe endophallus.

Endophallus(Eiiph).

— An

innerphallic

chamber

invaginatedatthe end of the ectophallus,

and

containing the truegonopore,or opening oftheejaculatory duct;typicallyaneversiblesacor tube, often mis- taken for theendof the ejaculatoryduct,butsometimesapermanently internal phallic structure that

may

attain a complex development.

(Preputialsac.)

Endotheca (Enth).

— The

inner wall of the phallotheca.

Epimerc.

— A

dorsalprocess of the phallobase.

NO. 14 INSECT

ABDOMEN —

SNODGRASS 63 Epiphallus (Epph).

— A

large,transversesclerite developed inthe dorsal wall of the base of the phallus, characteristic of Acrididae.

(Pseud^osterniteofWalker.)

Genital

chamber (GC). —

^{See bursagenitalis.}

Genital segment, or gonosomite.

—

Specifically the body segment bearing theopeningsof theprimary^genitalducts, or thesegment with which ^themedian gonopore is mostclosely associated, but alsoin a widersenseany oneof thesegmentsinaspecially differentiated genital regionof the body. In insects the genital segment isprimarily the seventhabdominalsomiteinthefemale andthe tenthinthe male, but secondarily the female genital segmentis usually the eighth or the ninthabdominalsomite,andthatof themaletheninth.

Gonapophysis (Gon.).

— Any

part ofa segmental appendageclosely associated with the genital segment and having

some

function inti- mately relatedtointromission of thesperm bythemaleor the deposi- tionof eggs bythe female. Inmale Malacostraca thegonapophyses are the endopodites of the^firstand second abdominal appendages

and

serve as intromittentorgans; in insectsthegonapophyses areappar- ently endites of the appendages of the eighth and ninth abdominal segments, presentinboth sexes of

some

Thysanura, formingthe usual ovipositor of femaleinsects.

Gcnopod

(Gp).

— An

appendage of the genital segmentor of an associated segment modified for

some

purpose in connection with copulation, intromission, oroviposition.

Gonopore

(Gpr).

— The

externalopeningofagenital duct,whether exposed, or concealedinasecondaryinvagination of the integument, such as thegenital

chamber

or anendophalliccavity.

Gonostyli.

— ^The

^styliof the ninthabdominal segmentof

some

male insects,presumablyappendicular parts of the coxopodites of thegono- pods,probably homologous with the movable claspers (harpagones) of

many

insects.

Gonotreme

(Gtr).

— The

external opening of the bursa genitalis, orgenitalchamber,in either sex;thevuivaof the female.

Harpagones

(Hrp.).

— Movable

periphallic appendicularorgans of theninthabdominal segmentof the male, individuallyprovided with muscles, probably derivatives of the gonostyli, sometimes supported on distinctcoxopodite plates. (Valvae, harpes.)

Hypandriiim

(IXS). — ^The

^{subgenitalplate}of the male, usually the sternumof the ninthabdominalsegment.

Hypomere. — A

ventral process of the phallobase.

Intromittent organs.

— ^Any

structure of the male serving for the introductionof thespermorspermatophores intothefemale, in

some

64

SMITHSONIAN MISCELLANEOUS

COLLECTIONS VOL. 95 cases thepaired penes,ininsectsusually themedianpenis,orphallus, hut in

many

otherarthropods modified appendages that assume the intromittent function, as in Araneida, Malacostraca,and Diplopoda.

Parameres

{Pnir).

—

Lateral processes or lobes of the phallobase, probably secondary outgrowths having norelation tothegonopods.

Penis {Pen).

— A

general term applied to any integumental out- growthcontaining theorificeof amalegenital duct,whetherintromit- tentinfunction ornot,including the pairedpenesof

many

arthropods, or a median penis (phallus); but the term is often used also in a restricted functional sense for the part of the phallus or any other intromittent organ insertedintothe female genital receptacle during mating.

The

primitive paired penes of most arthropods are on the bases of a particular pair ofsegmental appendages,oronthesternum

mesad

of theappendages.

A median

penis

may

beeithera penis con- jnnctus or a penis couiniuuisaccordingasitisformed bytheunionof a pair of penes, orbyasecondary

median

outgrowthof theintegument.

Periphallicorgans.

—

Peripheral genital processes of the ninth seg-

ment

or of other segments in the male genital complex of insects, including themovable claspers,or harpagones.

Phallicorgans.

— The

mediangenital structuresof maleinsectsim- mediatelyconcerned with the function of coition, or the introduction of thespermatozoaorspermatophoresintothe receptacular organ of the female; the phallic organs are highly variable, and are formed ontogenetically in various ways, but always independently of the periphallicorgans.

Phallobase (Phb).

— A

dilTerentiated basal part of the phallus, variable and often not distinct

from

the aedeagus.

(Teg men

in Coleoptera.

)

Phallocrypt (Crpt).

— A

pocket of the phallobase or of thegenital

chamber

wallcontaining the base of theaedeagusor of the ectophallus.

Phallomeres (Phin).

—

^{Phallicorganshavingthe}

^form

of lobespro- duced

from

thegenital

chamber

wallintheneighborhoodof thegono- pore; particularly developed in Blattidae and Mantidae, probably unitedin the

median

phallicorganof other Orthoptera,and perhaps represented bylobes that

form

the phallusin the ontogeny of

some

higherinsects.

Phallotheca {The).

— A

fold sometimes extended

from

the phallo- basearoundthebase of the aedeagus, orproducedas a tubular sheath enclosing thelatter,inexceptional cases replacing the aedeagus.

PhaUotreme

{Phtr).

— The

distal opening of the endophallus at the extremity of the ectophallus, the functional exitaperture of the genital tract

when

the true gonopore is contained in an endophallic chamber.

NO. 14 INSECT

ABDOMEN —

^SNODGRASS 65 Phallus (Pill).

— ^The

^{usual median penis or single} intromittent organofmaleinsects,variously formed and probably developedinde- pendentlyinseveral insectgroups.

Preputialsac.

—

^Seeendophallus.

Siibgenitalplate

(IXS). —

See hypandrium.

Titillators (Ttl).

—

^Distalexternalprocesses of theaedeagus.

Virga (Vir).

— A

terminal phallicspine or slenderrod usuallyaris- ing

from

the wall of the endophallus and therefore protractile with the aversion of thelatter.