Stewart B. Peck

Peck, Stewart B.

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A New Cave Catopid Beetle From Mexico, With a Discussion of its Evolution

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PSYCHE
Vol. 75 June, 1968 No. :z
A NEW CAVE CATOPID BEETLE FROM MEXICO,
WITH A DISCUSSION OF ITS EVOLUTION.*
BY STEWART B. PECK
Museum of Comparative Zoology, Harvard University
Most obligately cave-inhabiting (troglobitic) beetles belong to
the families Ca.rabidae, Catopidae, and Pselaphidae. From Mexico,
troglobitic species have been described in the Carabid tribes Trechini
and Agonini (Barr I966a, I966b, and Bolivar y Peltain and Hen-
drichs I964). The family Catopidae contains numerous troglobitic
species in several genera in Europe, and several species in the genus
PtomaphaTus in the United States (Jeannel I936, and Barr I963).
From Mexico, three species of Ptomaphagus have been recorded;
P. (Tupania) ]orticornis NIatthews, P. (tdelops) inermis Jeannel,
and P. spelaeus Bilimek (Jeannel 1936, Szymczakowski 1961 ). The
last of these was described rom Cacahuamilpa Cave, near Taxco, in
the state of Guerrero. It does not possess any ;structures .suggesting
that it is limited to a cavernico.lous life.
During the past few years, collections of six undescribed Ptomapha-
gus species from 12 Mexican caves have been sent to me by members
oi: the Association for Mexican Cave Studies for inclusion in a
revision of the genus. With the exception of a single emale, these
species show no structural specializations suggesting that they are
limited to caves. However, a collection was recently made in a
high altitude cave of a male of a highly modified species. This col-
lection reinforces current ideas on the origin of tropical troglobitic
beetles. The new species is described and discussed in this paper.
This paper is the first in a series on the evolution and biology of
the Ptomaphagus and other catopid beetles of North America. It
includes a departure from the usual method of describing cavernic-
olous species of Ptomaphagus. One morphological clue to the de-
*Manuscript received by the editor June 6, 1968
91
92 Psyche [June
gree of adaptation attained by a cave inhabiting beetle is the degree
of lengthening of the body and appendages. Measurements are used
extensively here to document these lengths. All measurements are
in millimeters and were made with a calibrated ocular micrometer.
The antennal segment measurements give maximum widths, and the
lengths do not include the basal bulb of articulation.
I thank James Reddell or making this and other collections o
Mexican Catopidae available to me for study. I also thank the many
members of the Association for Mexican Cave Studies who have
helped to collect these beetles. Proessor Philip J. Darlington, Jr.,
kindly reviewed the manuscript.
Ptomaphagus (Adelops) troglomexieanus n. sp.
Figs.
-5.
Holotype. Known only rom a unique, male, (deposited in. the
Museum o Comparative Zoology, Harvard University, MCZ type
number 3653), collected in Cueva de la Perra, at an elevation of
26o m (7oo feet), La Perra, 5 miles northwest of Gomez
Farias, Tamaulipas, Mexico; 28 January, 968; James ReddelI,
Robert W. Mitchell, Francis Rose, and John Geo.rge co.llectors.
Found in cave at base of flowstone slope.
Description. Length 4.0 mm. Width .7o mm. ’Co.lo.r dark
brown. Shape oblong, very convex, narrowing posteriorly (Fig. ).
Metathoracic wings absent. Eyes small, diameter o.3; facets present
but indistinct (Fig. 2); pigment absent. Antennae long and thin,
covering first third of elytra when laid back; club composed o last
rive segments; well supplied with abundant setae and with hairs
at ends o segments. Segment measurements, lengths followed by
widths; I, 0.34, o.Ii; II, o.2, 0.08; III, 0.29, 0.065; IV, o.9,
o.065; V, 0.26, o.o65; VI, 0.22, 0.08; VII, 0.22, o.ii; VIII, o.3,
o.o9; IX, o.8, o.; X, o.8, o.2; XI, o.25, o.. Pronotum
maximum width .66, one third before base; midline length I.X5;
hind angles a little less than right, acuminate; front angles broadly
rounded; base shallowly emarginate medial to hind angles; disc
uniformly covered with short golden pubescense and transverse strigae.
Elytra width .7o, widest a little behind base; length 2.70; gradually
narrowing in apical two thirds; apex rounded in male (female un-
known); clothed with dense golden hairs; strigae oblique to suture.
Hind tibia length r.46 width at middle o.3. Fore tarsi with first
three segments swollen in male. Mid tarsi and hind tarsi normal.
Hind tarsal segment lengths- I (basal) o.56; II o.3; III o.5; IV
o.z2; V o.9; chord o.f arc of claw o.3. Mesosternal carina low and
1968] Peck--- Catopid Beetle 93
uniformly rounded. Aedeagus (Figs. 4, 5) long and thin:in dorsal
view sides straight and parallel; in lateral view chord length .46,
curved at base, straight in middle, tapering gently to tip; tip slightly
acuminate in lateral and ventral views; five hairs on each side of
ventral surface; parameres equal, bearing two hairs at ends.
Diagnosis. The species is easily separated rom all other Ptoma-
phayus by the combination of the ollowing characters; the pig-
mentless but faintly faceted eyes whose maximum width is slightly
less than a third the distance rom the edge of the antennal socket
to the lateral carina of the head, the thin elongate antennae covering
the first third of the elytra when laid back, and the shape of the
aedeagus.
The abundant long pubescence of troglomexicanus may suggest
a relationship to P. spelaeus (a Mexican cavernicole) P. giaquintoi
Jeannel (a Guatemalan cavernicole) and an undescribed Guatemalan
cavernicole. However, these last three ,species are, one third smaller
in body length. The aedeagus of the third ’species is as straight but
not as thin as in troglomexicanus. The aedeagus has not been fig-
ured or described or the other two species.
The species groups of Ptomaphagus. The species describe.d in
this paper cannot at this time be placed in the phyletic groups of
Ptomaphagus recognized by Jeannel (949). Parts o his definitions
are based upon female characters which are unknown or this spe-
cies. Secondly, I have found some of Jea,nnel’s species groupings to
be polyphyletic assemblages which have convergently reached similar
levels o specialization. For instance, Jeannel places in the hirtus
group P. hirtus Tellkampf (a troglobite rom central Kentucky)
and P. mitchellensis Hatch (a litter inhabitant rom the Bla.ck
Mountains of North ’Carolina). Both beetles posses similar shapes,
but the very unusual aedea,gus o,f mitchellensis demonstrates that it
is distant from any other described No.rth American Ptomaphag,us.
The a.edeagus o hirtus indicates a close relation to P. nicholctsi Barr
and P. hubrichti Barr. Thesetroglobitic species rom Illinois and
Tennessee respectively were unknown to, Jeannel. I interpret .the
similarity of these, three troglobites to, be indi,cative of descent from
a single ancestral species independently .colonizing caves in the three
states.
In the future, it may prove necessary to recognize a .separate species
group to contain trolomexicanus and a, similar-sized, undescribed
species possessing small, pigrnentless eyes, and short, metathoracic
wings. The latter is presently known only from a single female rom
a gypsum cave in the Mexican state o.f Nuevo Leon.
PSYCHE, 1968 VOL. 75, PLATE
4
PECK CATOPID BEETLE
1968] Peck Catopid Beetle 95
Discussion. A comparative indication of the degree of cave adap-
tation possessed by P. troglomexicanus is given in Table I. The
species is compared to an epigean, a troglophilic, and a troglobitic
species rom the eastern United States: P. consobrinus Leconte is
ound in eastern North America t?rom Massachusetts to Iowa south-
ward to Florida and eastern Texas. It is a winged, eyed, t?orest
litter-inhabiting species. P. cavernicola Schwarz is a winged, large-
eyed species known only t?rom caves in a large arc t?rom Florida to
the Ozarks and eastern Iowa down to, central Texas and into north-
ern Nuevo Leon, Mexico. Though it can fly, it is apparently limited
to caves by ecological actors. P. loedingi Hatch is a wingless species
whose eyes are reduced to small, unpigmented, vaguely faceted
areolae. It occurs limited to caves in the vicinity o, Huntsville,
Alabama.
As the table shows, in this series of species, in a comparison ot? the
ratios of length to width o.t? three selected appendage segments the
numerical value increases as the species becomes more cave limited.
P. loedintTi possesses a more slender hind tibia, but troglomexicanus
possesses a more slender third antennal segment and first segment
of the hind tarsus. These differences may or may not prove to be
significant when the range of variation is learned for each species.
L/W L/W L/W EW/HW
FSHTar HTib TAS
P. consobrinus 4.5 8.0 1.25 .670
Jefferson Co., Mo.
P. caernicola 7.8 9.7 2.60 .650
Marvel Cave, Mo.
P. loedngi 9.0 12.0 3.60 .290
Shelta Cave, Ala.
P. troglomexicanus 10.0 10.7 4.50 .370
Table 1. Ratios of measurements of a specimen of four species of North
American Ptomaphagus, showing comparative lengths of appendage sections
and the size of the eye. Abbreviations" EW/HW, horizontal eye width
divided by width of head between edge of antennal socket and lateral
edge of head; FSHTar, first segment of hind tarsus; HTib, hind tibia;
L/W, length divided by maximum width; and TAS, third antennal segment.
EXPLANATION OF PLATE 4
Figures 1-5. Holotype male of Ptomaphagus troglomexicanus, from Cueva
de la Perra, Tamaulipas, Mexico. Fig. 1, dorsal view of adult, hairs and
strlgae omitted. Fig. :2, side view of head showing small pigmentless eye.
Fig. 3, ventral surface of genital segment. Fig. 4, ventral view of tip of
aedeagus. Fig. 5, lateral view of aedeagus.
96 Psyche [June
However, the similarities suggest a comparable level of cave adapta-
tion for the two species.
The last column of the table presents the data on the lateral width
of the eye compared to the lateral width of the head between the
antenna and the vertical carina forming the side of the head. The
eye o troglomexican,us is significantly larger than ot? loedintTi.
Appendage elongation may be a positive adaptive response to com-
pensate or the loss o. visual environmental information. With
longer appendages covered with more sensory hairs, a beetle could
receive information Crom a greater volume o its environment. Van-
del (965) has reviewed this argument, citing organisms which both
favor and refute it. He notes that since many groups ot? cave, animals
do no,t possess appreciably lengthened appendages, the. argument is
ina.dequately supported. However, we should not assume that all
taxa, after adaptation, will exhibit the same degree ot? morphologic
specialization. A situation may be adaptively solved by more than
one answer. Various physiological, behavioral, or other character-
istics may be ot? greater significance in some taxa not showing ap-
pendage elongation. Laboratory experimentation on the beetles’
sensory physiology may possibly tell us it? the tendency towards
appendage elongation is really the result ot? a positive selection /or
greater sensory capability.
In a totally dark environment, .eyes would seem to be of no selec-
tive value. With relaxed selection, loss ot? the organ system will
follow the accumulation of degenerative mutations. Sadffglu (I967)
has investigated this phenomenon in the Mexican cave fish Ano-
Dtichthys. The eyes of P. troglomexicanus, when compared to P.
loedingi, are not reduced in proportion to the degree ot? lengthening
of the appendages. This undoubtedly reflects the expected discordant
selective orces acting in the two sets o organ systems. The gradual
loss of eyes may be considered as a selectively neutral byproduct of
the genetic reorganization experienced during adaptation to a cave
environment (Barr 967).
Compared to temperate areas, very t?ew troglobitic beetles are
known rom tropical areas. The present view on the origin of
troglobitic beetles is that they evolved from epigean ancestors living
in the areas of the caves during the cold-wet glacial periods. The
entry into caves was brought about by changing climatic conditions;
the unsuitable warm-dry periods of the interglacials (Barr 968,
Jeannel 949). The interglacial epigean environment became un-
avorable for cold and moisture demanding species. They were
1968] Peck-- Catopld Beetle 97
forced into caves to find these conditions, and the populations were
isolated by extinctions ot? the local epigean species members. This
phenomenon also seems to be responsible tor the evolution o]? most of
the few tropical troglobitic beetles.
Perhaps the best faunally explored tropical caves are in the Congo
Republic o. Arica. A number o beetles live in these caves, but very
tew display any degree o .cave adaptation (Leleup 1956). Most
troglobites of temperate caves are derived from groups which are
extensively humus and moss inhabitants in montane forests. The high
orests of the central African mountains support a rich humus-in-
habiting beetle auna. The lack o African cave beetles may then
be explained by the possibility that Pleistocene climatic alterations
were not severe enough in the central ACrican mountains to sufficiently
depress the montane forest zones. The forests and their humus
faunas were not able to reach into the lowland Congo cave region.
The preadapted humus fauna never had access to the caves (Leleup
I956).
The possible climatic changes during the Pleistocene in Mexico
are poorly documented. However, since glacial moraines, exist some
2000 m below the present glaciers of some ot? the highest Mexican
mountains, we may assume that the montane orests ot the past en-
joyed conditions that were cooler and more moist than today. It is
significant that in the known Mexican cave carabid beetle auna,
reviewed by Barr (I966b), the majority ot the troglobites are rom
caves at high altitudes. It is similarly significant that P. troglomexi-
canus, the first described Mexican troglobitic catopid, occurs in a
cave at an elevation o 216o meters. All other Mexican cave Ptoma-
phagus that I have seen (six undescribed species rom I2 caves) are
from lower elevation caves and with one exception do not display
modifications for cave life. These latter species may not display cave
adaptations because they may be only recently isolated in caves by
extinctions or emigrations of the sunCace populations, or they may
be species that find caves to be as suitable a habitat as nearby
epigean environments. The suggested moss or humus-inhabiting
epigean species, or its descendant, ancestral to P. troglomexicanus,
may still exist at higher elevations. These possibilities can be an-
swered only by further collecting in the rich and varied environ-
ments found in Mexico.
LITERATURE CITED
BARR, THOMAS C., JR.
1963. Studies on the cavernlcole Ptomaphagus of the United States
(Coleoptera: Catopidae). Psyche, 70:
98 Psyche [June
1966a. New species of Mexis/hodrus from Mexican caves (Coleoptera:
Carabidae). Psyche, 73 112-115.
1966b. Mexican cave beetles of the family Carabidae. Association for
Mexican Cave Studies, Austin, Texas, Newsletter, 2" 182-185.
1967. Observations on the ecology of caves. American Naturalist, 101"
475-492.
1968. Ecological studies in the Mammoth Cave system of Kentucky.
I: The biota. Intern. J. Speleology, 3: 147-204.
BOLIVAR Y PELTAIN, C., AND j. HENDRICHS
1964. Agoninos cavernicolas nuevos del genero Rhadine de Nuevo Leon,
Coahuila, y San Luis Potosi (M6xieo) (Col., Carab.). Cieneia
(M6xieo), 23" 5-16.
JEANNEL, RENI
1936. Monographie des Catopidae. Mere. Mus. Nat. Hist. Nat., Paris,
hOUr. s6r., 1, 433 pp.
1949. Les col6optres eavernicoles de la r6gion des Appalaches. ]tudie
systematique. Notes Biospeologique, 4. Publ. Mus. Nat. Hist.
Nat., Paris, 12" 37-115.
LELEUP, N.
1956. La laurie cavernicole de Congo Belge et considerations sur les
Col6optres reliques d’Afrique intertropieale. Ann. Mus. Royal
du Congo Beige, Tervuren (Belgique), Ser. in-8 , Sci. Zool,
46:170 pp.
SADOLU, PERIHAN
1967. The selective value of eye and pigment loss in Mexican cave fish.
Evolution, 21: 541-549.
SZYMCZAKOWSKI, WACLAW
1961. Espces n6otropicales nouvelles ou peu connues de la famille
Catopidae (Coleoptera). Bull. Entomol. de Pologne, 31: 139-163.
VADEL, A.
1965. Biospeleology, the biology of cavernicolous animals. Pergamon
Press: New York. 524 pp.
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PSYCHEVol. 75 June, 1968 No. :zA NEW CAVE CATOPID BEETLE FROM MEXICO,WITH A DISCUSSION OF ITS EVOLUTION.*BY STEWART B. PECKMuseum of Comparative Zoology, Harvard UniversityMost obligately cave-inhabiting (troglobitic) beetles belong tothe families Ca.rabidae, Catopidae, and Pselaphidae. From Mexico,troglobitic species have been described in the Carabid tribes Trechiniand Agonini (Barr I966a, I966b, and Bolivar y Peltain and Hen-drichs I964). The family Catopidae contains numerous troglobiticspecies in several genera in Europe, and several species in the genusPtomaphaTus in the United States (Jeannel I936, and Barr I963).From Mexico, three species of Ptomaphagus have been recorded;P. (Tupania) ]orticornis NIatthews, P. (tdelops) inermis Jeannel,and P. spelaeus Bilimek (Jeannel 1936, Szymczakowski 1961 ). Thelast of these was described rom Cacahuamilpa Cave, near Taxco, inthe state of Guerrero. It does not possess any ;structures .suggestingthat it is limited to a cavernico.lous life.During the past few years, collections of six undescribed Ptomapha-gus species from 12 Mexican caves have been sent to me by membersoi: the Association for Mexican Cave Studies for inclusion in arevision of the genus. With the exception of a single emale, thesespecies show no structural specializations suggesting that they arelimited to caves. However, a collection was recently made in ahigh altitude cave of a male of a highly modified species. This col-lection reinforces current ideas on the origin of tropical troglobiticbeetles. The new species is described and discussed in this paper.This paper is the first in a series on the evolution and biology ofthe Ptomaphagus and other catopid beetles of North America. Itincludes a departure from the usual method of describing cavernic-olous species of Ptomaphagus. One morphological clue to the de-*Manuscript received by the editor June 6, 19689192 Psyche [Junegree of adaptation attained by a cave inhabiting beetle is the degreeof lengthening of the body and appendages. Measurements are usedextensively here to document these lengths. All measurements arein millimeters and were made with a calibrated ocular micrometer.The antennal segment measurements give maximum widths, and thelengths do not include the basal bulb of articulation.I thank James Reddell or making this and other collections oMexican Catopidae available to me for study. I also thank the manymembers of the Association for Mexican Cave Studies who havehelped to collect these beetles. Proessor Philip J. Darlington, Jr.,kindly reviewed the manuscript.Ptomaphagus (Adelops) troglomexieanus n. sp.Figs. -5.Holotype. Known only rom a unique, male, (deposited in. theMuseum o Comparative Zoology, Harvard University, MCZ typenumber 3653), collected in Cueva de la Perra, at an elevation of26o m (7oo feet), La Perra, 5 miles northwest of GomezFarias, Tamaulipas, Mexico; 28 January, 968; James ReddelI,Robert W. Mitchell, Francis Rose, and John Geo.rge co.llectors.Found in cave at base of flowstone slope.Description. Length 4.0 mm. Width .7o mm. ’Co.lo.r darkbrown. Shape oblong, very convex, narrowing posteriorly (Fig. ).Metathoracic wings absent. Eyes small, diameter o.3; facets presentbut indistinct (Fig. 2); pigment absent. Antennae long and thin,covering first third of elytra when laid back; club composed o lastrive segments; well supplied with abundant setae and with hairsat ends o segments. Segment measurements, lengths followed bywidths; I, 0.34, o.Ii; II, o.2, 0.08; III, 0.29, 0.065; IV, o.9,o.065; V, 0.26, o.o65; VI, 0.22, 0.08; VII, 0.22, o.ii; VIII, o.3,o.o9; IX, o.8, o.; X, o.8, o.2; XI, o.25, o.. Pronotummaximum width .66, one third before base; midline length I.X5;hind angles a little less than right, acuminate; front angles broadlyrounded; base shallowly emarginate medial to hind angles; discuniformly covered with short golden pubescense and transverse strigae.Elytra width .7o, widest a little behind base; length 2.70; graduallynarrowing in apical two thirds; apex rounded in male (female un-known); clothed with dense golden hairs; strigae oblique to suture.Hind tibia length r.46 width at middle o.3. Fore tarsi with firstthree segments swollen in male. Mid tarsi and hind tarsi normal.Hind tarsal segment lengths- I (basal) o.56; II o.3; III o.5; IVo.z2; V o.9; chord o.f arc of claw o.3. Mesosternal carina low and1968] Peck--- Catopid Beetle 93uniformly rounded. Aedeagus (Figs. 4, 5) long and thin:in dorsalview sides straight and parallel; in lateral view chord length .46,curved at base, straight in middle, tapering gently to tip; tip slightlyacuminate in lateral and ventral views; five hairs on each side ofventral surface; parameres equal, bearing two hairs at ends.Diagnosis. The species is easily separated rom all other Ptoma-phayus by the combination of the ollowing characters; the pig-mentless but faintly faceted eyes whose maximum width is slightlyless than a third the distance rom the edge of the antennal socketto the lateral carina of the head, the thin elongate antennae coveringthe first third of the elytra when laid back, and the shape of theaedeagus.The abundant long pubescence of troglomexicanus may suggesta relationship to P. spelaeus (a Mexican cavernicole) P. giaquintoiJeannel (a Guatemalan cavernicole) and an undescribed Guatemalancavernicole. However, these last three ,species are, one third smallerin body length. The aedeagus of the third ’species is as straight butnot as thin as in troglomexicanus. The aedeagus has not been fig-ured or described or the other two species.The species groups of Ptomaphagus. The species describe.d inthis paper cannot at this time be placed in the phyletic groups ofPtomaphagus recognized by Jeannel (949). Parts o his definitionsare based upon female characters which are unknown or this spe-cies. Secondly, I have found some of Jea,nnel’s species groupings tobe polyphyletic assemblages which have convergently reached similarlevels o specialization. For instance, Jeannel places in the hirtusgroup P. hirtus Tellkampf (a troglobite rom central Kentucky)and P. mitchellensis Hatch (a litter inhabitant rom the Bla.ckMountains of North ’Carolina). Both beetles posses similar shapes,but the very unusual aedea,gus o,f mitchellensis demonstrates that itis distant from any other described No.rth American Ptomaphag,us.The a.edeagus o hirtus indicates a close relation to P. nicholctsi Barrand P. hubrichti Barr. Thesetroglobitic species rom Illinois andTennessee respectively were unknown to, Jeannel. I interpret .thesimilarity of these, three troglobites to, be indi,cative of descent froma single ancestral species independently .colonizing caves in the threestates.In the future, it may prove necessary to recognize a .separate speciesgroup to contain trolomexicanus and a, similar-sized, undescribedspecies possessing small, pigrnentless eyes, and short, metathoracicwings. The latter is presently known only from a single female roma gypsum cave in the Mexican state o.f Nuevo Leon.PSYCHE, 1968 VOL. 75, PLATE4PECK CATOPID BEETLE1968] Peck Catopid Beetle 95Discussion. A comparative indication of the degree of cave adap-tation possessed by P. troglomexicanus is given in Table I. Thespecies is compared to an epigean, a troglophilic, and a troglobiticspecies rom the eastern United States: P. consobrinus Leconte isound in eastern North America t?rom Massachusetts to Iowa south-ward to Florida and eastern Texas. It is a winged, eyed, t?orestlitter-inhabiting species. P. cavernicola Schwarz is a winged, large-eyed species known only t?rom caves in a large arc t?rom Florida tothe Ozarks and eastern Iowa down to, central Texas and into north-ern Nuevo Leon, Mexico. Though it can fly, it is apparently limitedto caves by ecological actors. P. loedingi Hatch is a wingless specieswhose eyes are reduced to small, unpigmented, vaguely facetedareolae. It occurs limited to caves in the vicinity o, Huntsville,Alabama.As the table shows, in this series of species, in a comparison ot? theratios of length to width o.t? three selected appendage segments thenumerical value increases as the species becomes more cave limited.P. loedintTi possesses a more slender hind tibia, but troglomexicanuspossesses a more slender third antennal segment and first segmentof the hind tarsus. These differences may or may not prove to besignificant when the range of variation is learned for each species.L/W L/W L/W EW/HWFSHTar HTib TASP. consobrinus 4.5 8.0 1.25 .670Jefferson Co., Mo.P. caernicola 7.8 9.7 2.60 .650Marvel Cave, Mo.P. loedngi 9.0 12.0 3.60 .290Shelta Cave, Ala.P. troglomexicanus 10.0 10.7 4.50 .370Table 1. Ratios of measurements of a specimen of four species of NorthAmerican Ptomaphagus, showing comparative lengths of appendage sectionsand the size of the eye. Abbreviations" EW/HW, horizontal eye widthdivided by width of head between edge of antennal socket and lateraledge of head; FSHTar, first segment of hind tarsus; HTib, hind tibia;L/W, length divided by maximum width; and TAS, third antennal segment.EXPLANATION OF PLATE 4Figures 1-5. Holotype male of Ptomaphagus troglomexicanus, from Cuevade la Perra, Tamaulipas, Mexico. Fig. 1, dorsal view of adult, hairs andstrlgae omitted. Fig. :2, side view of head showing small pigmentless eye.Fig. 3, ventral surface of genital segment. Fig. 4, ventral view of tip ofaedeagus. Fig. 5, lateral view of aedeagus.96 Psyche [JuneHowever, the similarities suggest a comparable level of cave adapta-tion for the two species.The last column of the table presents the data on the lateral widthof the eye compared to the lateral width of the head between theantenna and the vertical carina forming the side of the head. Theeye o troglomexican,us is significantly larger than ot? loedintTi.Appendage elongation may be a positive adaptive response to com-pensate or the loss o. visual environmental information. Withlonger appendages covered with more sensory hairs, a beetle couldreceive information Crom a greater volume o its environment. Van-del (965) has reviewed this argument, citing organisms which bothfavor and refute it. He notes that since many groups ot? cave, animalsdo no,t possess appreciably lengthened appendages, the. argument isina.dequately supported. However, we should not assume that alltaxa, after adaptation, will exhibit the same degree ot? morphologicspecialization. A situation may be adaptively solved by more thanone answer. Various physiological, behavioral, or other character-istics may be ot? greater significance in some taxa not showing ap-pendage elongation. Laboratory experimentation on the beetles’sensory physiology may possibly tell us it? the tendency towardsappendage elongation is really the result ot? a positive selection /orgreater sensory capability.In a totally dark environment, .eyes would seem to be of no selec-tive value. With relaxed selection, loss ot? the organ system willfollow the accumulation of degenerative mutations. Sadffglu (I967)has investigated this phenomenon in the Mexican cave fish Ano-Dtichthys. The eyes of P. troglomexicanus, when compared to P.loedingi, are not reduced in proportion to the degree ot? lengtheningof the appendages. This undoubtedly reflects the expected discordantselective orces acting in the two sets o organ systems. The gradualloss of eyes may be considered as a selectively neutral byproduct ofthe genetic reorganization experienced during adaptation to a caveenvironment (Barr 967).Compared to temperate areas, very t?ew troglobitic beetles areknown rom tropical areas. The present view on the origin oftroglobitic beetles is that they evolved from epigean ancestors livingin the areas of the caves during the cold-wet glacial periods. Theentry into caves was brought about by changing climatic conditions;the unsuitable warm-dry periods of the interglacials (Barr 968,Jeannel 949). The interglacial epigean environment became un-avorable for cold and moisture demanding species. They were1968] Peck-- Catopld Beetle 97forced into caves to find these conditions, and the populations wereisolated by extinctions ot? the local epigean species members. Thisphenomenon also seems to be responsible tor the evolution o]? most ofthe few tropical troglobitic beetles.Perhaps the best faunally explored tropical caves are in the CongoRepublic o. Arica. A number o beetles live in these caves, but verytew display any degree o .cave adaptation (Leleup 1956). Mosttroglobites of temperate caves are derived from groups which areextensively humus and moss inhabitants in montane forests. The highorests of the central African mountains support a rich humus-in-habiting beetle auna. The lack o African cave beetles may thenbe explained by the possibility that Pleistocene climatic alterationswere not severe enough in the central ACrican mountains to sufficientlydepress the montane forest zones. The forests and their humusfaunas were not able to reach into the lowland Congo cave region.The preadapted humus fauna never had access to the caves (LeleupI956).The possible climatic changes during the Pleistocene in Mexicoare poorly documented. However, since glacial moraines, exist some2000 m below the present glaciers of some ot? the highest Mexicanmountains, we may assume that the montane orests ot the past en-joyed conditions that were cooler and more moist than today. It issignificant that in the known Mexican cave carabid beetle auna,reviewed by Barr (I966b), the majority ot the troglobites are romcaves at high altitudes. It is similarly significant that P. troglomexi-canus, the first described Mexican troglobitic catopid, occurs in acave at an elevation o 216o meters. All other Mexican cave Ptoma-phagus that I have seen (six undescribed species rom I2 caves) arefrom lower elevation caves and with one exception do not displaymodifications for cave life. These latter species may not display caveadaptations because they may be only recently isolated in caves byextinctions or emigrations of the sunCace populations, or they maybe species that find caves to be as suitable a habitat as nearbyepigean environments. The suggested moss or humus-inhabitingepigean species, or its descendant, ancestral to P. troglomexicanus,may still exist at higher elevations. These possibilities can be an-swered only by further collecting in the rich and varied environ-ments found in Mexico.LITERATURE CITEDBARR, THOMAS C., JR.1963. Studies on the cavernlcole Ptomaphagus of the United States(Coleoptera: Catopidae). Psyche, 70:98 Psyche [June1966a. New species of Mexis/hodrus from Mexican caves (Coleoptera:Carabidae). Psyche, 73 112-115.1966b. Mexican cave beetles of the family Carabidae. Association forMexican Cave Studies, Austin, Texas, Newsletter, 2" 182-185.1967. Observations on the ecology of caves. American Naturalist, 101"475-492.1968. Ecological studies in the Mammoth Cave system of Kentucky.I: The biota. Intern. J. Speleology, 3: 147-204.BOLIVAR Y PELTAIN, C., AND j. HENDRICHS1964. Agoninos cavernicolas nuevos del genero Rhadine de Nuevo Leon,Coahuila, y San Luis Potosi (M6xieo) (Col., Carab.). Cieneia(M6xieo), 23" 5-16.JEANNEL, RENI1936. Monographie des Catopidae. Mere. Mus. Nat. Hist. Nat., Paris,hOUr. s6r., 1, 433 pp.1949. Les col6optres eavernicoles de la r6gion des Appalaches. ]tudiesystematique. Notes Biospeologique, 4. Publ. Mus. Nat. Hist.Nat., Paris, 12" 37-115.LELEUP, N.1956. La laurie cavernicole de Congo Belge et considerations sur lesCol6optres reliques d’Afrique intertropieale. Ann. Mus. Royaldu Congo Beige, Tervuren (Belgique), Ser. in-8, Sci. Zool,46:170 pp.SADOLU, PERIHAN1967. The selective value of eye and pigment loss in Mexican cave fish.Evolution, 21: 541-549.SZYMCZAKOWSKI, WACLAW1961. Espces n6otropicales nouvelles ou peu connues de la familleCatopidae (Coleoptera). Bull. Entomol. de Pologne, 31: 139-163.VADEL, A.1965. Biospeleology, the biology of cavernicolous animals. 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A New Cave Catopid Beetle From Mexico, With a Discussion of its Evolution

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