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TABLE OF PROBABLE TERMINAL PHYLOGENETIC LINES IN THE HOLARCTIC PIERINÆ,
(The differences in specialization are relative and unequal.)
Non-typical Yellows Typical Yellows Non-typical Whites
THE CHARAXINÆ. The Nymphalidæ proper appear dichotomous. The main ascending branch is represented by the Argynninæ, running up into the Nymphalinæ. This branch is characterized by a short furcation of iii, with iiis, and the genera may be called the “short forks." The second branch represents an earlier condition of the Nymphalids in which this furcation is more or less extended and the genera may be known as “long forks.” Just as the passage from the Argynninæ to the Nymphalinæ by the continued greater absorption of ii and iii of hind wings may be considered to have gradually occurred, so the transformation of the “long forks" into “short forks" is inevitable by the progress of iii, toward the outer margin of the wing. But, other characters considered, the existing “ long forks" seem to hold together on a distinct phylogenetic line. In Anæa we have an existing “long fork” which has lost its taxonomic character in this direction. In Euschatzia (type morvus) we have an allied Charaxid which still retains the character. Mr. Scudder having in 1875 (1. C., 111) fixed the type of Anæa as troglodyta, this action could not be properly subverted by Schatz, who subsequently made the same species the type of his genus “Pyrrhandra, which name must fall. For morvus, more generalized than the species of Anæa, I choose the generic name Euschatzia. Genera like Aganisthos, Kallima and Anæa appear to represent in succession Consul, Charaxes, Hypna, Prepona, typical “ long forks."
In Charaxes veins iii, and iii; fuse at base for a short space, only about one-sixth of the length of iiis. If this short fusion were absent we should have wing agreeing so far with that of Hesperia, that all the veins are separate, and no furcation, consequent upon the absorption of iii, by iiis, has taken place. Thus in the primitive Nymphalidæ, represented more nearly by the Charaxinæ, the veins were probably all separate. And probably also in the whole group Hesperiades. In fact the hypothesis suggests itself that the lepidopterous wing may have originally shown a series of longitudinal and independent veins, connected by a system of cross veins and without furcations. The disappearance of the cross veins would allow of the contact of the longitudinal veins. This state of affairs would in turn lead to their partial absorption and consequent furcation. We may have in the Hesperiadæ and Tortricidæ existing stages of this evolutionary change in the lepidopterous wing.
To resume: Butterflies like Athyma and even Adelpha seem to find their natural place in the Nymphalinæ. But, when we come to the west coast of South America, we find in Megalura a form which shares the taxonomic character of the secondaries with the Nymphalinæ, while iri, of primaries reaches apex. Perhaps here we come upon a fresh phylogenetic line, and the meeting of i, ii and iii of the hind wings at one point is no longer a reliable index of a nearer blood relationship.
A STRANGE AFRICAN PIERID. A genus which has reached the grade of specialization of Nathalis, Mancipium and Pontia, and even gone beyond it, is represented by the strange little African butterfly Gonophlebia paradoxa. In his recent work Mr. Reuter has classified this butterfly as follows: “Papiliones: Pierididæ : Pseudopontiinæ : Pseudopontiidi: Pseudopontia." The major clamp in this declensional series—Papiliones —we can at once discard, since no proof has, nor apparently can ever be offered, that the Whites are phylogenetically connected with the Swallowtails. Further, if we may trust Mr. Scudder, the whole series of etymological changes must go by the board, since Pseudopontia is a synonym of Gonophlebia.
Two common butterflies will help us in understanding the venation of Gonophlebia : rhamni and sinapis. How the veins may be twisted to sustain the new shape of the wing, here assumed very probably under the influence of mimicry, is certainly taught us by rhamni, in which the branches of the radius are bent upward to sustain the expanded costa of primaries. Our strange African butterfly has the veins still more strongly bent out of their normal course to meet the required shape of its funny round wings. In Gonophlebia veins iv, and iv, have left the cross vein and spring, one following the other, from the main branch of the radius, vein iiig tot 5, outside of the closed cell. This is an amplification of the usual Pierine movement of the upper branches of the median system of veins. This, not the whitish color, stamps Gonophlebia as an offshoot of the Pierid stem. Gonophlebia is even more easily recognized as a Pierid than Leptidia sinapsis, in which iv, has not left the cross vein. But, despite the contrasted shape of their wings, it is not impossible that Leptidia and Gonophlebia are isolated survivors of the same phylum.
The extraordinary movement of the middle branch of the median
series, vein iv,, in following the lead of iv,, proves Gonophlebia to be a highly specialized form. The neuration shows us that there is no contradiction offered to the view that Gonophlebia is a specialized Pierid and, in order to make this still plainer, we will study it a little closer.
What gives the pattern of the veining its singularity, and affords a faint reminiscence of the Pericopids, is the tendency to run apart which the veins display in Gonophlebia. The veins are bent more or less out of their usual course, and this is especially the case with v, on both wings. But all this effort is clearly exerted in order to sustain the circular shape of the wings and keep the thin membrane taut. On the secondaries the expansion of the rounded costal margin has to be performed solely by the radius, in its single specialized condition, without branches. And how is this infrequent task accomplished? The simple vein is bent upwards, near the middle, at a nearly right angle, supporting and anastomosing with vein ii; thence again, less abruptly descending, the radius runs outwardly to external margin below the apices, while vein ii itself is continued to the apex of the wing. Nature wished to make a spherical wing with no greater number of sustaining rods than go to support the longer wings of other butterflies, or even the narrow and extended wings of Leptidia. And thus, with the same economy of material, is the end attained. There arise no new veins, no complexity of machinery astonishes. We have the old veins in new position, but still showing the Pierine movement in specialization.
If Gonophlebia is the pattern of the veining so transformed, it is small wonder that Mr, Butler should deny and Mr. Scudder question its being a butterfly. Added to this the antennæ lack the regulation knob, which would allow Mr. Butler to place it among the “ Rhopalocera." A puzzle to the classificators and a seduction to Mr. Reuter to a waste of category, this frail butterfly has evidently suffered many “vicissitudes of the voyage" along the road it has traveled and which may not be so very far now from its ending.
This strange butterfly is the only diurnal I have yet met with in which vein ix is retained on hind wings.
EXPLANATION OF Plate I.
The figures are obtained by combined photographic process. The veins are numbered according to the system Redtenbacher-Comstock.
in =radius, iv = media, v= cubitus. Fig. 1. Pontia daplidice. Type of genus. Attention is called to the three
branched radius. A specialized type. Vein iii, in original position. 2. Tetracharis cethura. Type of genus. Compare the four-branched
radius with the five-branched radius of Euchloe. Vein iii, in original
position. Fig. 3. Anthocharis ausonides. Vein iii, has moved forward to a point con
siderably beyond the cross-vein. Attention is called to the diminished extent of vein iiic. A more specialized form than A. belemia. For this type Mr. Scudder uses Synchloe, but contrary to custom. The reason for rejecting Midea for genutia does not seem to me
tenable. Fig. 4. Euchloe cardamines. Type of genus. The five-branched radius
shows vein iii, in original position above the cell. E. stella agrees.
A generalized type of the group. Fig. 5. Nathalis iole. Type of genus. A specialized type with three
branched radius. Fig. 6. Terias hecabe. Type of genus. A subspecialized type with four
branched radius. Vein viii of primaries fairly distinct. A mere
rudiment of vein i of hind wings. Fig. 7. Gonophlebia paradoxa. Type of genus. Vein viii of primaries pres
ent, short, close to vii. On secondaries three internal veins. Type of subfamily Gonophlebianue. Compare text.