NO. 13 STAPH YLINIDAE BLACKWELDER 61 The maxillae present a rather large amount of variation in form

NO. 13

STAPH

YLINIDAE

BLACKWELDER

61

62 94 extendsdistadalmost or quite as faras thegalea. These formsgen- erally have both these structures less hairy and frequently

armed

with spines.

Of

the species examined Gcodromiciis, Pelecomalium, Leptochirus,Emnalus, Trigonurus,allthe Oxytelini, Steninae,Paede- rinae (fig. 17

D),

Staphylininae (fig.

2G),

Oxyporinae,Tachyporini, and Bolitobiinihavethelacinia

much

shorterthan the galea, whereas

itiselongateinMicropeplus,Tanyrhinus, Lathrimaemn,Phloeocharis, Pseudopsis,Osorhis (fig.17E), Habroccrns,

Hypocyptus

(fig. 17C), and all theAleocharinae.

The

maxillary palpi are four-segmented in all the species except Aleochara and Baryodina (fig. 17G), in which there is a small ad- ditional fifthsegment.

With

the exception ofStenus (fig. 17F),the first segment is always small and geniculate. It is apparently im- movably united to the second segment, at least in Thinopinus (fig.

17

A). Any

of the succeeding segments

may

be

much

expanded, as the second inMicropeplus (fig. 17^I),the third in

Hypocyptus

(fig.

17

C)

and Paederus (fig. 17

K),

or the fourth in Pinophilus (fig.

17 D). Occasionally the fourth is longer thanany of theothers, as in Acylophorus (fig. 17

H)

and Osorhis (fig. 17E), but

more

fre- quentlyit is greatly reduced, asin Gastrolobium (fig. 17B),

Hypo-

cyptus (fig. 17C), and Stenus (fig. 17F). InPaederus (fig. 17

K)

the terminaloneisshort,truncated,andstronglycompressed.

In nearly every labium studied the

mentum

and

submentum

are theonly heavilysclerotized parts.

The submentum

iscontinuous with thegula between the tentorial pits and is generally separated atthe sides

from

the postgenae by the submental sutures. These sutures

may

becomplete

from

the base of the

mentum

to the tentorial pits, they

may

be incomplete either anteriorly orposteriorly, they

may

be unitedonthemidline for a distancein front of thepits,orthey

may

beentirely lacking.

They

arecomplete in

Lathrimaeum

(fig. 12

H),

Stenus (fig.12G), Astenus^(fig. 12B),

Hypocyptus

(fig. 12F),and

all others not listed in the three following categories.

The

anterior endsof the sutureshavedisappearedto avaryingextentinPseudop-

sis, Trachysectus, Orus, Philonthus (fig. 12 J), ^Cafius, CreopJiilus, Ocypus, Thinopinus, Hadrotes,GIciuis, Acylophorus, Quedius,Tachi- nus,Tachyporus, and Erchonms.

They

arevisibleonlyatthe anterior endinTanyrhinus (fig. 12A). InTrigonurus,Bledius, Platystcthus, Oxytclus,Aploderus(fig.12E), and Osoriustheyhave

become

united in frontof the tentorial pitsso thatthe

submentum

is awholly dis- tinctsclerite.

The

sutures are apparently entirely lacking in Micro- peplus,

Eunmlus

(fig. 12C),

Metoponcus

(fig. 12I),and

Oxyporus

(fig. 12D).

NO. 13 STAJ'llVLINIDAE

BLACKWELDER

63

The

mentuni is frequently united to the

submentum

between the projecting anterior corners of the latter. It is usually trapezoidal in form but

may

be variously lobed in front, as in Leptochirus (fig.

18G),

Oxyponis

(fig. 18

A),

and Liparocephahis (fig. 18E). It fre- quently bearsafew large setaeand isnearlyalwayssparselysetwith large pores.

Fig. 18.

—

Intrafamily variationintheform andstructureofthe labium. (Onlythebasalsegmentofthepalpishown.)

A,OxyponislateralisGrav. B, OsoriusimiiuiiisShp. C,Lathriiiiaciiiii pictiiiii Fvl. D, Baryodina himaciilata Grav. E. Liparoccplialiisbrcz'ipciniis Makl. F, Trigoiuinis crotchi Lee. G, Leptochirus mcxicauus Er. H, Gastrolohiiiin bi- color (Grav.).

The prementum

isfrequentlyonly partlysclerotized. InTrlgonurus

(fig.18

F)

there are three small triangularscleriteslyinginthe

mem-

brane between the paraglossal lobes; in Osorius (fig. 18

B)

there is

a single large quadrate plate anterior to the base of the palpi; in

Oxyponis

(fig. 18

A)

theentirebasalpartof the

prementum

issclero- tized as alongplate;and inotherformsthere is

more

or lesssclero- tizationof the areabetweenthementiim andthebase of thepalpi.

The

5

64 COLLECTIONS VOL. 94 palpigers

may

not bedififerentiated fromthe rest of the prementum, and are frequently entirely

membranous.

Frequently there are no glossal or paraglossal lobes visible, as in Osorius (fig.

i8B)

and Leptochirus(fig.i8G),butin

some

formstheyappeartohaveunited intoa pairof lobes orevenasingle lobe,asinLathrbnacuut(fig.i8

C)

and Gastrolohimn(fig. i8

H)

^,whereasinothers there arebothglossae and paraglossae distinct, as in Baryodina (fig.

i8D).

In Liparo- cephalus (fig.

i8E)

there is a united glossa or ligula which ispro- longed into a cyHndrical sclerotized piece projecting cephalad for nearly half the lengthof thefirstsegmentof the palpi.

Any

of these parts

may

occasionally bear large setae or minute setulae. It

must

always be borne in

mind

in examining the labium that the

hypopharynx

almost invariably is furnished with a pair of lobes bearing

combs

ofsetaewhichproject

up

behindtheparaglossae andarelikely tobemistakenfor them.

They

arealways

membranous

like the paraglossae, and the distinction between them is sometimes

difficulttomake.

The number

of segments in the labial palpi is said to vary from oneto four.

None

have been recorded with less than three except

from

the subfamilyAleocharinae, and the only examples with four are therealso. Inalmostnocases arethere definite articulationsbe- tween ^the segments of thepalpi, each one being united to the next byarelativelywidearea of

membrane.

Frequentlyalsothesegments are ratherindefinitely sclerotizedbut usuallysufficiently sotoprevent anydifficultyincountingthem.

No

specimens have been studied which have only one segment in thelabial palpi.

One

specieshas been observed with two-segmented palpi. ThisisLiparoccphalus (fig. 19B),inwhichthe basalsegment

ispartiallydividedintotwo. Itisevidentlyanintermediate stepinthe formation of either the three-segmented

from

the two-segmented condition or the reverse.

The

closely related genus Dianlota fre- quently showsboth the extremes and all the intermediate steps in a singlelotof theonespecies.

The

three-segmented condition of the labial palpi is almost uni- versal throughout the family, but a great deal of variation in form

isapparent.

As

arulethelabial palpuscannot besaid tobefiliform, though certainsegments

may

be slenderincertainspecies.

The

basal segment

may

be longer than eitherof the others, as in Habroceriis (fig. 19

E)

and Stenus (fig. 19C),orshorter,asin

Hypocypfus

(fig.

19

F)

and Osorius (fig. 19 J). ^It

may

be rather strongly geniculate as inStenus(fig. 19

C)

and Osorius (fig. 19 J), or

may

be largeand

NO. 13

STAPH

YLINIDAE

BLACKWELDER

65 cylindrical as in Aleochara (fig. 19

A)

and Hahrocerus (fig. 19E).

The

middle segment

may

be greatlyexpandedas inStenus (fig. 19

C)

or very short asinTrigonurus (fig. 19

H). The

terminal segmentis generally smalland

narrow

asinStenus (fig.19C),

Hypocyptus

(fig.

19F),and Paederus (fig. 19^I),butisgreatlyexpandedin

Oxyporus

(fig. 19

D)

into averylarge,compressed,obconicalbody.

nthe labial palpi.

A, Aleochara lata Grav. B, Liparoccphahis brevipennis Makl. C, Stenus sculptilis Csy. D, OxyporuslateralisGrav. E,HabrocerusschzvarsiHorn. F, Hypocyptus longicornis (Payk.). G, Pinophilus parvipcnnis Csy. H, Trigo- nurus crotchi Lee. I,PaederuslaetusEr. J,OsoriusmundusShp.

A

four-segmented labialpalpus

was

foundonlyin Aleochara (fig.

19

A). The

palpiof otherAleocharinaeare said tobesimilar.

THE THORAX

A

great deal of variationisexhibitedintheshapeof the

pronotum

(figs.20,21). Itishardto classifythetypes, asnearlyallgradations aretobe found andnearly everygenus oreven species is

somewhat

different

from

its near, as well as

from

its

more

distant, relatives.

Figures 20 and 21

show some

of the forms that occur.

Almost

anv

66

VOL. 94

Fig. -Intrafamily variation of thepronotum (continued on fig. 21).

A,Lathrofropisjacobiiia(Lee). B, Lithocharisocliracea (Grav.). C,Ocypus ater (Grav.). D, Fclecomaliiini tcstaceum (Mann.). E, Trigoiuirus crotchi Lee. F,Pscudopslsoblitcrata Lee. G, Leptochirus inexicanus Er. H, Proteinus limbatitsMakl. LPlatystcthusaiiicricamisEr. J,Stilicusangularis Er. K,Aleo- chara lata Grav. L, Acylophonis flavicoUis Sachse. M, Tachyporiisjocosiis Say. N, Micropepluspunctatus Lee.

f!

NO. 13

STAPH

YLINIDAE

BLACK WELDER

(>7 of these

may

be foundinany of the larger subfamiHes. It isobvious thattheshapeof the

pronotum

cannotbeusedinthe higherclassifica- tion. In certaingroupsitisusefulingenericandspecificsegregation.

The

^inflexed portion of the

pronotum

is generally closely united with certain elements of the ventral surfaceandwill be discussedin the sectiondealingwiththe prosternalarea.

The

ventral aspect of theprothoraxaffords a considerable

amount

of variation in structure.

The

fundamental condition is frequently

Fig.21.

—

Intrafamily variation of thepronotum (continuedfromfig.20).

A, Metoponcusx'arians Slip. B, Cafius Hthocharinus Lee. C, Lorinota cingu- lata (Lee.); D, Osorins nmndiis Shp. E, Liparocephalus brevipennis Makl.

F, Gcodroiniciis hrumwus (Say). G, Hypocyptus longicornis (Payk.). H, ApJodcrus linearis Lee.

obscuredbythereduction of scleritesandthe obliterationof sutures, but severalimportantcharacters areavailable.

The amount

of inflection of the

pronotum

varies somewhat, but the size of the postcoxal lobe is

more

important and usable. These lobes tendtoclosethecoxal cavitiesbehind, being almost successful inLeptochints(fig.22 F). In Lithocharis(fig.22

B)

and Xantholinus

(fig.23

D)

they are lackingentirely.

The

sternum varies greatly in length.

The

longest exposed area occurs in Leptochints (fig. 22F), but the large posterior lobe of

68

VOL.

94

Astenus (fig. 23

A)

surpasses it

somewhat

though covered by the coxae. Aleochara (fig. 22

A)

has the shortest and most reduced stenium. This structure is often produced posteriorly between or underthecoxae. Trigonnrus (fig.22Id) has averysmall projection,

Fig. 22.

—

Intrafamily variationintheform andstructureofthe prosternalarea (continuedonfig.23).

A,AleocharalataGrav. B, Lithocharis ochracca (Grav.). C, Osornismundus Shp. D, Triganurus crotchi Lee. E, Bledius monstratus Csy. F, Leptochirus mexicanusEr.

while theextreme developmentisreachedinAstenus(fig.23

A)

and Pinophilus(fig. 23 B). In theselast

two

the prosternal lobe reaches the lobesof the inflexedpronotum,thereby closing the coxal cavities behind. In Pinophilus thisclosure iscompleted bythe actual fusion of thesternallobeto theunderside of thelateral lobes.

NO. 13

STAPH

YLINIDAE

BLACK WELDER

69 InXantholinus(fig.23

D)

and

Metopoucus

thereisa pair of large triangularscleritesanteriorto thesternum andlying freeintheedge of the anteriorforamen.

They

occurinnoothergroupandare said tobe present in only a few generaof the Xantholinini.

The

spiraclesof themesothorax normallyliein theintersegmental

membrane

inthevicinityof thepronotallobes.

They

usuallylieinthe

2^.

—

Intrafamily variationintheform andstructureofthe prosternal area (continuedfromfig.22).

A,Astcmisdiscopunctatus (Say). B,Pinofhilus parvipcnnis Csy. C, Lorinota cingulata (Lee.). D, XantholinuspicipennisLee.

unsclerotized

membrane

asinLithocharis (fig.22

B)

and Trigonurus

(fig. 22

D),

but are incorporated intothe posterior lobe of the pro- sternuminPinophilus (fig.23 B). InAleochara (fig.22

A)

they are surrounded bythesmall peritremes,whileinLorinota(fig.23

C)

these scleritesare so large as completelyto closethecoxal cavitiesbehind.

The

shape of the elytron is almost as individual as that of the

pronotum

(fig.24). ^{It is} impossibleto classifytheseorgansby form,

94

Fig. 24.

—

Intrafamily variationofthe elytra.

A, MetoponciisvariiDis Shp. B,TanyrhinussingnlarisMann. C, Trigonurus crotchi Lee. D, Geodroinicus bnmneus (Say). E, Acylophonts flatncolUs Sachse. F, Protcinus UmbatiisMiikl. G, OxypornslateralisGrav. H, Osorius mimdtts Shp. I,Blediiis ino)istratusCsy. J,TachyponisjocosiisSay. K,Platy- stethus aniericanus Er. L, Pacderilhis pugetensis Csy. M, Xenodusa sharpi Wasni. N, Micropcplns punctatus Lee. O, Alcochara lata Grav. P, Liparo- cephahisbrevipenms Makl.

NO. 13

STAPHYLINIDAE BLACKWELDER

7I