Article beginning on page 339.
Psyche 9:339-343, 1900.

Full text (searchable PDF)
Durable link: http://psyche.entclub.org/9/9-339.html

The following unprocessed text is extracted from the PDF file, and is likely to be both incomplete and full of errors. Please consult the PDF file for the complete article.

PSYCHE.
ARE THE MALLOPHAGA DEGENERATE PSOCIDS?
BY VERNON L. KELLOGG, STANFORD UNIVERSITY, CALIF. In a paper published in 1896* I effect-
ively concealed some remarks which I
hoped might revive interest in a question that of late years has been allowed to
drop into an undeserved innocuous de-
suetude. This question or problem con-
cerns the phylefic relations of those in- sects which have been shuffled about by
systematic entomologists more perhaps
than any other insects, those namely that began as a great host forming the order
Pseudo-Neuroptera, were later divided
into smaller hosts ordinally classified
as Pseudo-Neuroptera, Platyptera and
Corrodentia, and which now are wholly
freed from genealogical entanglements
with each other by appearing in the text- books as a series of small orders, each
present order corresponding to the fam-
ilies of the earlier catch-all orders.
That
my remarks had no attention was their
deserved fate; deserved for allowing
themselves to get into a too corpulent
'new species " paper. Such papers are
properly filed for reference, not read, and so my intention of giving the Psocidae
'New MitIlophtigil TI, from land birris, together with an account of the Mallrtphagoui'-; tnnuthparts. Contrib. to Biol, from Hopkins Seaside Laboratory of Leland Stanford, Jr. University, No. VII, 117 pp. 14 plates, November, 1896, the ill name of being the ancestors or the very immediate relatives of the ancestors of the biting bird lice (Mallophaga) got itself simply filed for reference.
But I did mean to ask seriously the
question whether or not the Psocids
and the Mallophaga are not more nearly
related than their present classification would .lead one to suspect; whether in-
deed they should not properly compose
a single order readily separable into two sub-orders, but obviously linked by a
common descent. And in the last five
years I have, with the handling of many
more Mallophaga, and the occasional
reexamination of the Psocid body, had
my notions only made more distinct, and
my inclination to answer 'the question in favor of the common origin of the two
groups only strengthened. And the
reasons for this believing are outlined in the following paragraphs.
While recognizing clearly the occur-
rence among unrelated forms of "paral-
lelism of development " and " parallelism of structure" there is yet a certain de- gree of similarity approaching identity, which, when reached, we
can explain
only on the basis of community of origin, and descent. This degree of approxi-




================================================================================

340 PSYCHE [May. iqoz
mate identity is, of course, not deter-
minable by arbitrary convention, nor, in the present state of zoological science, by quantitative measure, but its recognition is in most cases obvious to all naturalists, and the power to recognize parallelism
when existing, and to recognize identity due to common origin and descent when
existing is simply one of the required
qualifications of the competent systematic zoologists. In my belief the Mallophaga
and Psocidae possess in common certain
peculiar and characteristic structural fea- tures (coupled with corresponding physi- ological features) whose practical iden- tity must be ascribed to community of
origin and which thus reveal a commu-
nity of descent on the part of the insects themselves.
In my paper New Mallophaga I1
previously referred to, are described and illustrated in detail the mouthparts of
four Mallophagous genera (pp. 431-457
plates LX-LXII). Three of these
genera thus described, and ten other
genera examined, although not described
in 'detail, are found to possess a well- developed peculiar pharyngeal or oeso-
phageal sclerite characteristically con- stant in position and shape, and of
important use in the manipulation of
the dry food (bitten off parts of feathers) of the insects. (In four of these genera there appear to bc species lacking the
sclerite - or, at least, having it in such weakly chitinized condition as to make
it invisible when the undissected head of the specimen is examined.) In five
Mallophagous genera this sclerite is ab- sent. In the four remaining known
genera of the order no specimens are at
hand. This peculiar sclerite is a thick- ening of the chitinous intima of the pha- rynx, and appears as a bonnet-shaped
sclerite lying on the ventral wall of the pharynx, with hollow part upward, with
median groove closed behind, projecting
processes at the interior angles, and a
pair of long slender "bonnet string"
pieces, which project dorsally and pass
on either side of the pharynx, or oeso-
phagus, upward and around it, and attach by their ends to the dorsal wall of the
head. Opening into the median groove
from its ventral side is a small duct,
which, followed to its source, is seen to come from the union of a pair of ducts,
each one of which comes from an oval
gland lying ventral to the sclerite, and fitting into a concavity on the anterior end of a weakly chitinized, pedicel-like structure, which projects backward and
is attached by a foot-shaped expansion
to a large, strong muscle. (Figures of
this oesophageal sclerite and glands are given on plate LXII in New Mallophaga,
11.)
Apart from this peculiar addition to
the usual biting insect mouth, two of the four genera of Mallophaga whose mouth-
parts were carefully studied were found
to possess certain peculiar "forks" in the mouth, which by dissection are seen to
be very small chitinous rods lying inside of thc mouth above the labium whose
posterior ends attach to the ventral wall of the head by muscles, and whose
anterior ends are strongly forked or




================================================================================

~ay, q021 PSYCHE. 841
bifurcated and project through the ven-
tral wall of the mouth thus lying free
and uncovered in the mouth cavity.
Although not observed in the other two
genera of Mallophaga dissected, it is not at all certain that they are not present, their extreme minuteness and delicacy
making their discovery a matter of diffi- culty. (Figures of these "forks" are
given on plate LX, New Mallophaga,
11.)
For the rest, the Mallophagous mouth
is of simple biting type with a consider- able reduction of the maxillae, the max- illary palpi being wholly wanting.
Thanks to Edward Burgess the anat-
omy of the mouth of the Psocidae has
been known since 1878.~ The unusual
features, long familiar to entomologists as curious and unique structures, of the Psocid mouthparts are the so-called
"forks" of the mouth and the so-called
"oesophageal bone " and paired " lingual glands " of the pharynx. Burgess's
description of one of the Psocid folks is as follows. "This is a slender, more or
less curved chitinous rod with a forked
bifid tip, and two or three times as long as the outer lobe. The distal portion
of the fork, about one-third or less of its length, projects through the lining mem- brane of the mouth. At this point the
fork is stoutest, and from it, it tapers to either end, the outer portion being stout- er than the inner. The membrane
where it is united with the fork is deli- *The anatomy of the headand thestructure of the maxillae in the Paocidae.
Proc. Bat. Sod Nat. Hist., 1878, Vol.
XIX, p. 29i.pl. V111.
cate and elastic, thus permitting the fork to be projected forward or drawn back
at will. Within the head the fork is
held in position by muscles inserted on
its base, which unite it with the lobe and stripes of the maxilla, and by a ligament which runs backward to the top of the
head." (Figures of the "forks" are
given in Burgess's paper, and copied in
plate LXIV of New Mallophaga, 11.)
'
I have simply to add that the Psocid
"forks" are in structure, position and
attachments practically identical with the Mallophagous "forks," and whether Bur-
gess's view that the forks are new and
independent mouthparts, or Scudder's
view that they are the modified maxillar' laciniae, be true, the Mallophagous forks can readily be homologized with them,
for the Mallophagous maxillae have but
one terminal lobe and would be not at
all sorry to find in the forks their lost laciniae !
Burgess's description of the '( oesopha- geal bone " of the Psocidae is as follows : "Below the opening of the oesophagus
lies a bone which may be fancifully lik- ened to a lady's bonnet upside down ;
the high front lie's along the oral cavity at about half way up ; two narrow exten- sions, representing the bonnet strings,
run forward and upward, embracing the
oesophagous. The great bundles of
short muscles filling the large vaulted
clypeus are attached to the ends of
these strings, and by their contraction
close the oesophagus. Just below the
front a fine duct opens which is the
common duct of a pair of lingual glands.



================================================================================

342 PSYch?E. [May, 190%
These can be seen through the semi-
transparent mentum and labium, offering
an irregular, obovate. outline. A short
duct from the lower end of each gland
leads into a common duct which opens
in the oesophageal bone as already de-
scribed. The ducts curve over the lower
end of the glands and run up their pos-
terior surface, to which they are soldered nearly to the top. The line of the ducts together with .the lateral outlines, give the glands a three-cornered shape, some- what like that of a butternut. A little
triangular cup fits on the summit of each gland, and on it is inserted a suspensory muscle, the upper end of which is
attached to the cranium." (Figures of
"bone" and ducts arc given in Bur-
gess's paper and copied in plate LXIV
of New Mallophaga. 11.)
I have again simply to add that the
"oesophageal bone " and its accessory
"lingual glands " of the Psocidae, are
surely the "oesophageal sclerite " and
its accessory glands of the Mallophaga-
The important thing about this corre-
spondence between "forks" and oesopha-
geal structures in the two groups is that the same structures do not occur else-
where among insects.
Perhaps the most familiar Psocid form
is the degenerate genus Atropos, It is
very different from the winged forms ; in fact it is the "link" that connects the
winged Psocidae with the Mallophaga.
In Atropos as in the Mallophaga there
are no traces of wings ; the whole body, head, thorax, and abdomen is flattened
exactly as in the Mallophaga ; the meso- thoracic and meta-thoracic segments are
fused to form a single segment, one of
the characteristic structural conditions of the Mallophaga while the great devel- opment of the clypeus and the restriction of the mouthparts to the ventral aspect
of the head. so characteristic of the bird- lice, is quite as characteristic of this degraded Psocid. So too the peculiar
condition of the labrnrn in the Mallo-
phaga lying as it does on the ventral
aspect of the produced clypeus finds an
identical repetition in Atropos. The man- dibles of Atropos present a really striking similarity with those of the Amblycerous group of the Mallophaga, the details of
teeth, condyles, facets and musculation
being extraordinary alike.
The internal anatomy of the Psocids
has yet to be worked out in detail,
although Nitzsch, in 182 I, described
the alimentary canal and the reproduc-
tive organs of Clothiffa pulsatoria (a
degraded wingless form much like
Atropos). He found the alimentary
canal to be very simple, without special crop or proventriculus, and with a simple elongate stomach consisting of a sac-like anterior part and a longer tubular pos-
terior part. There are four Malpighian
tubules. The intestine is very short, its rectal portion being as long as all the
rest of it. The ovaries consist of five
egg-tubes on each side ; connected with
the oviduct there is a peculiar accessory gland consisting of a sac containing
other small sacs each with an elongate
efferent duct, the number of these sec-
ondary sacs varying from one to four




================================================================================

May, rpal PSYCHE. 343
according to the individual. The testis
is a simple capsule ; connected with the base of the jaculatory duct there is a
pair of elongate accessory glands or
vesiculae seminales.
The internal anatomy of the Mallo-
phaga has been described by Grosse
(for the species " Tetro/hfhalmns chil-
ensis " = Menofon titan), by Nusbaum,
and latest and in most detail by Snod-
grass,* who studied comparatively the
various organs in several species. With
reference to the alimentary canal, Mal-
pighian tubules and reproductive organs
(the only organs which have been de-
scribed for the Psocidae and can there-
fore be compared, with the similar Mall- ophagous organs), Snodgrass finds that
the alimentary canal in the Mallophaga
presents two types, one being "simple,
having no special development at any
part" and possessed by the Amblycera,
(one of the two sub-orders into which I
have divided the Mallophaga) the other
"complicated by a lateral and backward
prolongation of the crop so that the
latter forms a large expanded divertic-
ulum of the oesophagus." This second
type is possessed by all the members of
the sub-order Ischnocera. In the simple
type the canal corresponds thoroughly
well with that of Clothilla, even to the shortness of the intestine as compared
with the rectum. With regard to the
Malpighian tubules Snodgrass finds their number constant throughout the Mallo-
phaga. That number is four, as in
*Siiod rats R. E.. The Anatomy of the Mallophaga, in New ~afiopl~i!,! III. Contrib. to Bid from the Hopkins Seaside Laboratory of Leland Stanford Tr. University. no. XIX, pp. 224, plates 17 plates.
Clothilla. Finally comparing the rcpro-
ductive organs Snodgrass finds the num-
ber of egg tubes to bc five in the sub-
order Ischnocera and to vary from three
to five in the Amblycera. In Clothilla
there are five. In the Mallophaga the
testes are either two or three in number on a side and there is a pair of seinina- vesicles, with its two members either
distinct or more or less fused. In Cloth- ilia there is one testis on a side, and a pair of seminal vesicles.
So far as the con~parison can bc made
then it is obvious that a great similarity in character of internal organs exists in the degraded wingless Psocid Clothilla,
and the Mallophaga.
Finally
it is interesting to note the
similar habits of Atropos, Clothilla and the other dust-lice or book-lice (including all the degenerate wingless Psocids) and the biting bird lice or Mallophaga.
These book-lice feed on dry dead organic matter, such as wood and paper, dried
insects and dried bird and mammal
skins ; the Mallophaga feed exclusively
on the dry dead dermal scales, hairs and feathers of mammals and birds. I have
found Atropos often in the nests of birds; was it feeding on the feathers there ?
What a simple step from the feathers off the bird to the feathers 011 the bird!
Then Atropos would be a bird-louse and
a new and rather aberrant genus of Mal-
lophaga !
As a matter of fact in collcc-
tions of Mallophaga sent in to me, all the specimens presumably collected from the
bodies of birds, I have in a few, (very
few, truly,) instances received specimens of Atropos.




================================================================================