Variation as Specially Influenced by Locality
The phenomena of variation as influenced by locality have not hitherto received much attention. Botanists, it is true, are acquainted with the influences of climate, altitude, and other physical conditions, in modifying the forms and external characteristics of plants; but I am not aware that any peculiar influence has been traced to locality, independent of climate. Almost the only case I can find recorded is mentioned in that repertory of natural-history facts, “The Origin of Species,” viz. that herbaceous groups have a tendency to become arboreal in islands. In the animal world, I cannot find that any facts have been pointed out as showing the special influence of locality in giving a peculiar facies to the several disconnected species that inhabit it. What I have to adduce on this matter will therefore, I hope, possess some interest and novelty.
On examining the closely allied species, local forms, and varieties distributed over the Indian and Malayan regions, I find that larger or smaller districts, or even single islands, give a special character to the majority of their Papilionidæ. For instance: 1. The species of the Indian region (Sumatra, Java, and Borneo) are almost invariably smaller than the allied species inhabiting Celebes and the Moluccas; 2. The species of New Guinea and Australia are also, though in a less degree, smaller than the nearest species or varieties of the Moluccas; 3. In the Moluccas themselves the species of Amboyna are the largest; 4. The species of Celebes equal or even surpass in size those of Amboyna; 5. The species and varieties of Celebes possess a striking character in the form of the anterior wings, different from that of the allied species and varieties of all the surrounding islands; 6. Tailed species in India or the Indian region become tailless as they spread eastward through the archipelago; 7. In Amboyna and Ceram the females of several species are dull-coloured, while in the adjacent islands they are more brilliant.
Local variation of Size.—Having preserved the finest and largest specimens of Butterflies in my own collection, and having always taken for comparison the largest specimens of the same sex, I believe that the tables I now give are sufficiently exact. The differences of expanse of wings are in most cases very great, and are much more conspicuous in the specimens themselves than on paper. It will be seen that no less than fourteen Papilionidæ inhabiting Celebes and the Moluccas are from one-third to one-half greater in extent of wing than the allied species representing them in Java, Sumatra, and Borneo. Six species inhabiting Amboyna are larger than the closely allied forms of the northern Moluccas and New Guinea by about one-sixth. These include almost every case in which closely allied species can be compared.
| Species of Papilionidæ of the Moluccas and Celebes (large). | Closely allied species of Java and the Indian region (small). | ||
| Expanse. Inches. | Expanse. Inches. | ||
| Ornithoptera (Helena Amboyna) | 7.6 | O. Pompeus | 5.8 |
| O. Amphrisius | 6.0 | ||
| Papilio Adamantius (Celebes) | 5.8 | P. Peranthus | 5.8 |
| P. Lorquinianus (Moluccas) | 3.8 | ||
| P. Blumei (Celebes) | 5.4 | P. Brama | 4.0 |
| P. Alphenor (Celebes) | 4.8 | P. Theseus | 3.6 |
| P. Gigon (Celebes) | 5.4 | P. Demolion | 4.0 |
| P. Deucalion (Celebes) | 4.6 | P. Macareus | 3.7 |
| P. Agamemnon, var. (Celebes) | 4.4 | P. Agamemnon, var. | 3.8 |
| P. Eurypilus (Moluccas) | 4.0 | P. Jason | 3.4 |
| P. Telephus (Celebes) | 4.3 | ||
| P. Ægisthus (Moluccas) | 4.4 | P. Rama | 3.2 |
| P. Milon (Celebes) | 4.4 | P. Sarpedon | 3.8 |
| P. Androcles (Celebes) | 4.8 | P. Antiphates | 3.7 |
| P. Polyphontes (Celebes) | 4.6 | P. Diphilus | 3.9 |
| Leptocircus Ennius (Celebes) | 2.0 | L. Meges | 1.8 |
| Species inhabiting Amboyna (large). | Allied species of New Guinea and the North Moluccas (smaller). | ||
| Papilio Ulysses | 6.1 | P. Autolycus | 5.2 |
| P. Telegonus | 4.0 | ||
| P. Polydorus | 4.9 | P. Leodamas | 4.0 |
| P. Deiphobus | 6.8 | P. Deiphontes | 5.8 |
| P. Gambrisius | 6.4 | P. Ormenus | 5.6 |
| P. Tydeus | 6.0 | ||
| P. Codrus | 5.1 | P. Codrus, var. papuensis | 4.3 |
| Ornithoptera Priamus, (male) | 8.3 | Ornithoptera Poseidon, (male) | 7.0 |
Local variation of Form.—The differences of form are equally clear. Papilio Pammon everywhere on the continent is tailed in both sexes. In Java, Sumatra, and Borneo, the closely allied P. Theseus has a very short tail, or tooth only, in the male, while in the females the tail is retained. Further east, in Celebes and the South Moluccas, the hardly separable P. Alphenor has quite lost the tail in the male, while the female retains it, but in a narrower and less spatulate form. A little further, in Gilolo, P. Nicanor has completely lost the tail in both sexes.
Papilio Agamemnon exhibits a somewhat similar series of changes. In India it is always tailed; in the greater part of the archipelago it has a very short tail; while far east, in New Guinea and the adjacent islands, the tail has almost entirely disappeared.
In the Polydorus-group two species, P. Antiphus and P. Diphilus, inhabiting India and the Indian region, are tailed, while the two which take their place in the Moluccas, New Guinea, and Australia, P. Polydorus and P. Leodamas, are destitute of tail, the species furthest east having lost this ornament the most completely.
| Western species, Tailed. | Allied Eastern species not Tailed. |
| Papilio Pammon (India) | P. Thesus (Islands) minute tail. |
| P. Agamemnon, var. (India) | P. Agamemnon, var. (Islands). |
| P. Antiphus (India, Java) | P. Polydorus (Moluccas). |
| P. Diphilus (India, Java) | P. Leodamas (New Guinea). |
The most conspicuous instance of local modification of form, however, is exhibited in the island of Celebes, which in this respect, as in some others, stands alone and isolated in the whole archipelago. Almost every species of Papilio inhabiting Celebes has the wings of a peculiar shape, which distinguishes them at a glance from the allied species of every other island. This peculiarity consists, first, in the upper wings being generally more elongate and falcate; and secondly, in the costa or anterior margin being much more curved, and in most instances exhibiting near the base an abrupt bend or elbow, which in some species is very conspicuous. This peculiarity is visible, not only when the Celebesian species are compared with their small-sized allies of Java and Borneo, but also, and in an almost equal degree, when the large forms of Amboyna and the Moluccas are the objects of comparison, showing that this is quite a distinct phenomenon from the difference of size which has just been pointed out.
In the following Table I have arranged the chief Papilios of Celebes in the order in which they exhibit this characteristic form most prominently.
| Papilios of Celebes, having the wings falcate or with abruptly curved costa. | Closely allied Papilios of the surrounding islands, with less falcate wings and slightly curved costa. |
| 1. P. Gigon | P. Demolion (Java). |
| 2. P. Pamphylus | P. Jason (Sumatra). |
| 3. P. Milon | P. Sarpedon (Moluccas, Java). |
| 4. P. Agamemnon, var. | P. Agamemnon, var. (Borneo). |
| 5. P. Adamantius | P. Peranthus (Java). |
| 6. P. Ascalaphus | P. Deiphontes (Gilolo). |
| 7. P. Sataspes | P. Helenus (Java). |
| 8. P. Blumei | P. Brama (Sumatra). |
| 9. P. Androcles | P. Antiphates (Borneo). |
| 10. P. Rhesus | P. Aristæus (Moluccas). |
| 11. P. Theseus, var. (male) | P. Thesus (male) (Java). |
| 12. P. Codrus, var. | P. Codrus (Moluccas). |
| 13. P. Encelades | P. Leucothoë (Malacca). |
It thus appears that every species of Papilio exhibits this peculiar form in a greater or less degree, except one, P. Polyphontes, allied to P. Diphilus of India and P. Polydorus of the Moluccas. This fact I shall recur to again, as I think it helps us to understand something of the causes that may have brought about the phenomenon we are considering. Neither do the genera Ornithoptera and Leptocircus exhibit any traces of this peculiar form. In several other families of Butterflies this characteristic form reappears in a few species. In the Pieridæ the following species, all peculiar to Celebes, exhibit it distinctly:—
| 1. Pieris Eperia | compared | with | P. Coronis (Java). |
| 2. Thyca Zebuda | ″ | ″ | Thyca Descombesi (India). |
| 3. T. Rosenbergii | ″ | ″ | T. Hyparete (Java). |
| 4. Tachyris Hombronii | ″ | ″ | T. Lyncida. |
| 5. T. Lycaste | ″ | ″ | T. Lyncida. |
| 6. T. Zarinda | ″ | ″ | T. Nero (Malacca). |
| 7. T. Ithome | ″ | ″ | T. Nephele. |
| 8. Eronia tritæa | ″ | ″ | Eronia Valeria (Java). |
| 9. Iphias Glaucippe, var. | ″ | ″ | Iphias Glaucippe (Java). |
The species of Terias, one or two Pieris, and the genus Callidryas do not exhibit any perceptible change of form.
In the other families there are but few similar examples. The following are all that I can find in my collection:—
| Cethosia Æole | compared | with | Cethosia Biblis (Java). |
| Eurhinia megalonice | ″ | ″ | Eurhinia Polynice (Borneo). |
| Limenitis Limire | ″ | ″ | Limenitis Procris (Java). |
| Cynthia Arsinoë, var. | ″ | ″ | Cynthia Arsinoë (Java, Sumatra, Borneo) |
All these belong to the family of the Nymphalidæ. Many other genera of this family, as Diadema, Adolias, Charaxes, and Cyrestis, as well as the entire families of the Danaidæ, Satyridæ, Lycænidæ, and Hesperidæ, present no examples of this peculiar form of the upper wing in the Celebesian species.
Local variations of Colour.—In Amboyna and Ceram the female of the large and handsome Ornithoptera Helena has the large patch on the hind wings constantly of a pale dull ochre or buff colour, while in the scarcely distinguishable varieties from the adjacent islands of Bouru and New Guinea, it is of a golden yellow, hardly inferior in brilliancy to its colour in the male sex. The female of Ornithoptera Priamus (inhabiting Amboyna and Ceram exclusively) is of a pale dusky brown tint, while in all the allied species the same sex is nearly black with contrasted white markings. As a third example, the female of Papilio Ulysses has the blue colour obscured by dull and dusky tints, while in the closely allied species from the surrounding islands, the females are of almost as brilliant an azure blue as the males. A parallel case to this is the occurrence, in the small islands of Goram, Matabello, Ké, and Aru, of several distinct species of Euplœa and Diadema, having broad bands or patches of white, which do not exist in any of the allied species from the larger islands. These facts seem to indicate some local influence in modifying colour, as unintelligible and almost as remarkable as that which has resulted in the modifications of form previously described.