520 PROCEEDINGS OP THE NATIONAL MUSEUM

Figs. 145-146.—Cokdulegasterdoksalis. 145,A.NymphwithPROTECTn^Ecoat ofalgae. 145, ExirvT-i. 140.Femaleovipositing instreambed.

NO. 2192.

DRAOONFLIES, CALIFORNIA AND NEVADA— KENNEDY.

521

I.iater Williamson observed Cordulegaster maculatus Selys ofthe eastern United States whilein the actof ovipositing, which hede- scribed as follows:^{^}

Cordulegaster maculatuswaa observedto flydownfromtrees, alightingon ^algae- covered rocks in thestreambed. Onportionsoftheserocksnot coveeredwithwater theycrawledaboutinanawkward,almost crippledmanner,thrustingtheirabdomen withmuchcommotionintothe algaebeneaththe water.

An

interesting

summary

ofourknowledgeof oviposition in Cordu- legasterisgiven

by

Dr.C.

Wesenb

erg-LundinOdonaten-Studien.^

It is interesting to note thatthisvery special formof ovipositor

may

notbeofanygreat systematicsignificance. Itoccursin allof thefewcordulegasterine Odonata known. It is found inthelibel- lulinegenusUracis (seefig.144, F, Uracis ovipositrix Calvert),thesev- eral species ofwhichoccurinSouth America andhavehabitsofovi- position similar tothoseofCordulegasterexcept that theyoviposit in the

mud

about the water.

More

strangeyetistliefactthatasmgle species of thelargegenus

Sympetrum

ofthe North Temperate

Zone

hasthis

same

highlyspecialized ovipositor. Thisspecies,

Sympetrum

cordulegaster (Selys) (seefig. 144, E), occursin northeast Asia and nothing is

known

of its habits. While the majority of theSympe- trumshave no ovipositorand oviposit

by

washingthe eggsfrom the tip oftheabdomen, oneor twoAsiatic specieshaveextraordinarily long vulvarlaminaeand formasort ofconnectingseriesbetweenthe numerous species ofSympetrum.withno laminaeorverysmall ones andtinsfreakspecies,

Sympetrum

cordulegaster (Selys),withthevul- varlaminae longest and united into a monster ovipositor (seefig.

144,E),

Sympetrum

frequens (Selys),with small vulvarlaminae (fig.

144,A) and

Sympetrum

eroticum(Selys),fromJapan, with verylarge vulvarlaminae but these not united into an ovipositor (fig. 144,

C

andD). Figure144,B,is

Sympetrum

matutinumRis,anintermediate form. Thesewidely scatteredcases of this specialformof ovipositor areanexcellentexampleofconvergent evolution.

As

neitherof the westernspecies of Cordulegaster has been well figured, Ihave

shown

inthefigures

some

ofthe pecuHaritiesof struc- ture and have represented the color patterns diagrammatically.

Diadema

issHghtlylargerthan dorsalis.

A

male andfemaleof dia-

dema

measure as follows: Male, abdomen, 64

mm.,

hind wing, 4S;

female,abdomen,65

mm.,

hind wing,55. Male andfemaleof dorsalis measureas follows: Male, abdomen,55

mm.,

hind wing, 44; female, abdomen, 57

mm.,

hind

mng,

45.

As

is

shown

in the figures 135, diadema,and141,dorsalis,theappendages on segment10ofthemale do notdiffernoticeably. Figure 136showsthepecuhar armatureofthe tibiaindiadema whichdoes notdifferfromthatin dorsalis. Figure140 showsthe organsofsegment2 ofthemaledorsalis,whichareverysimi-

1OhioNat.,vol.7,1907,p. 144.

2Mitthl.biol.Siisswasserlab.Hallerod(Denmark),No.16,p. 187.

522 PROCEEDINGS OF THE NATIONAL MUSEUM.

vol.52.

lar tothose ofdiadema. Theseare characterized

by

the verylarge swollenheadofthe penisand

by

thetbinsheU-hkeanteriorhamules.

Figure 143showsthe eggsof dorsalis

drawn

to the

same

scale asthe abdomiDal segments9and 10,figure 142. Figures137,diadema,and 142, dorsalis,

show

theovipositors ofthe females.

The

ovipositor con- sistsofa largeventralovipositorproperwliich arisesfromthe eighthseg-

mcnt

andin

thenymph

isdividedlongitudinally. Tins

may

bo homolo- gousto the ovipositorinthe Aeshninae. Intheconcavedorsal sur- face of thislieapair ofslenderorganswhichinthe

nymph

arisefrom the ventral surfaceof segment9. Theseindiadema do notextend caudad beyond theapices of the appendages ofsegment 10, butin dorsalis are

much

longer. These,because theyarisefrom segment9,

may

be homologoustothegenitalvalvesof theaeshninedragonflies, thoughtheir position intheimagoesisjustthe reverseofthese parts inthe Aeshninae.

Incolorthetwospeciesaresimilar.

The

generalcolor in teneralsis

chocolate

brown

which,in age,

may become

almostblack.

The

mark- ings arepureyellow.

The

frons indiademais black

mth

a

yeUow

ovalonitsdorsalsurface whilein dorsalisit isyellowwithadark

band

across itsanterior face.

The

markingsof the

abdomen

in diadema are characterized

by

the yellow obliqueringson segments3 to 8,and indorsalis

by

the subcircular dorsal spotson segments2 to 7.

The

eyesin dorsalisaregray. (Seefigs.133-134and 138-139.)

The

n3niiphs of Cordulegaster are short-legged, slow-movingcrea- turesandare usuallyabundantinthe streamsoftheCoast Mountains.

They

occurwithOctogomjyhus

nymphs

intheleafytrashoftheeddies, butare alsofoundcrawling slowlyaboutover thebedofthe stream.

Tlieir very slow and apparently cautious

movements

donot betray them,andthey carry with

them

further protectioninthe coatoflong hairs which collects dirt and on which flourishes a thickgrowth of filamentous algae (seefig. 145,A). Becauseof thiscoveringof dirt and algae the

nymph,

thoughon an otherwisebarren bottom, will usually escape the closest scrutiny of the collector, forit does not appear any different from a stick or stone covered with dirt and aquatic growths.^

At

emergence,which takes placeinJune (I foundasingleexuvia

May

31),the

nymphs

crawlfrom1to5 feet

up

thetrunkofthenearest alder tree (seefig.145, B).

A

^male

was

rearedinthe laboratory,but thehourofemergencewasnotascertained. Thisspeciesspends four yearsintheeggand

nymphal

stages.

The

following tableshows the four sizesof

nymphs

Icollectedon StevensCreek (Santa.ClaraCounty,Cahfornia)during the pastsum- mer.

The

measurementusedisthewidthof thehead (eye to eye)

;

1OnMission Creek, Santa Barbara,California, Ifoundnymphsof dorsalisburiedin flocculentsilt,as isdescribedbyDr.J.G.Needham(N.Y.StateMus.Bull. 47, 1901, p. 473) forthe various easternspecies of thisgenus.

NO. 2192.

DRAOONFLIES, CALIFORNIA AND NEVADA— KENNEDY ₅₂₃

lengthisunreliable,for

some

have swollen and

some

have shrunken in alcohol.

Collected.