The Island of Formosa, lies in the western Pacific Ocean, between the Southern and Eastern China Seas and is separated from the Chinese mainland by the Formosan Strait, which has a width of about ninety miles in its narrowest part. It is two hundred and five miles long and from sixty to eighty miles broad, having seven hundred and thirty-one miles of coast-line and an area of 13,429 square miles, being thus nearly of the same size as Kiushiu, the southernmost island of Japan proper.
The island is traversed throughout its length by a fine mountain range, which reaches an altitude of from 8,000 to 12,000 feet, Mt. Niitaka (14,270 ft.) stands in the middle and Mt. Silvia (12,480 ft.) in the north. In addition, along the eastern shore there are coast ranges of considerable height, the bases of which form magnificent cliffs from fifteen to twenty-five hundred feet high. Thus the middle part and the eastern side of the island are mountainous, while the west is covered by fertile plains.
Because of the above mentioned topography, there are very few rivers on the eastern coast, while on the western coast there are many of considerable length, namely, Tamusui, Hozan, Koro, Daian, Daito, Dakusui, Seira, Shinkobi, Sobun, and Shimo-Tamusui, of which the last-named is the largest. In addition to these, there is a lake called jitsugetsutan (Lake Candidius), which has a small outlet into the River Dakusui.
Until a comparatively recent date the Island of Formosa was a «terra incognita» to the naturalist, and the fresh-water fishes, which are especially valuable as confirming the geographical relationship between isolated islands and continents, were quite unknown.
When Albert Günther published his «Catalogue of Fishes» in 1859-1870, he had only sixteen species of Formosan fresh-water fishes to enumerate. After a lapse of more than twenty years Jordan and Evermarm reported one hundred and eighty-six species of Formosan fishes, including twenty-seven which were found in the fresh waters. Since that publication the efforts of Regan, Jordan and Richardson, and Boulenger have raised the total number of Formosan fresh-water fishes from thirty-two to forty-three.
In the present paper is given a record of an extensive collection of the fresh-water fishes of the Island of Formosa, chiefly made by Mr. T akeo Aoki, my assistant, during the years 1915-1917, making an addition of seven new genera, fifteen new, and eighteen unrecorded species.
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The typical portions of the collections, including the type specimens, and the others which are described in the present paper, are preserved in the Carnegie Museum in Pittsburgh. A second set, including cotypes of the new species, is deposited in the Museum of Leland Stanford junior University. The remainder is reserved for the Institute of Science, Government of Formosa.
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Distribution: British India; Ceylon; Borneo; Sumatra; Mindanao; Luzon; Bengal; Siam; Hindostan; Indo-China; Formosa; China; Amur Province.
Synopsis of the Formosan species
Body torpedo-shaped, posterior part compressed, anterior part depressed; head rather elongate, depressed, its dorsal profile gradually inclined anteriorly; snout more or less produced, anterior margin obtusely rounded, interorbital space flat; eyes relatively small, superior and exceedingly anterior; nostrils separated, superior, the anterior in a short tube, in contact with the upper lip, the posterior in front of eye above; mouth oblique, large, its angle extending beyond the posterior margin of orbit; a band of small teeth on outer edge of jaws, a band of large, wide-set, caniniform teeth on palatine and Inner side of lower jaw; upper jaw protractile, slightly shorter than the lower.
Dorsal fin very long, with numerous spine-like rays, low anteriorly gradUally lengthening posteriorly, when depressed the tip of fin reaching beyond root of caudal; the pectoral obtusely rounded, nearly twice as long as broad, reaching beyond the middle of ventral: ventral fins small, not reaching vent; anal similar to the dorsal, inserted beneath anterior third of the base of dorsal, when depressed reaching beyond the root of caudal; caudal fin squarish, with rounded tip; caudal peduncle very short, deep, strongly compressed laterally.
Body covered with rather large cycloid scales with irregular concentric rings and radiated stria-; top of head and cheeks covered with large scales; lateral line discontinuous, undulating, running along the center of body from base of caudal to just over third anal ray, thence upward for two rows of scales, forward sixteen rows, downward one row, and then forward to edge of gill-opening.
Color in formalin olivaceous brown above, paler below; a row of twelve dark gray blotches along the base of dorsal, partly on the fin, partly on body; below these, but above the lateral line, another row of nine similar, but larger, blotches, extending anteriorly to the upper posterior border of eye, running below the upward curve of lateral line and forming a continuous longitudinal band; below this another row of about seventeen similarly colored, irregular blotches, extending from the base of pectoral posteriorly along lower edge of lateral line to base of caudal; below this another row of irregular and lightercolored blotches; head olivaceous brown, s~reaked with irregular lines -of black above; a band of dark brown as wide as pupil, but becoming wider posteriorly, running from postero-inferior edge of eye to the middle of base of pectoral; lower part of head paler; dorsal fin marbled with dark; membrane of caudal fin dark, its rays dusky brown, two vertical stripes of gray color near the base; anal fin with seven dark blotches at the base of posterior half, its membrane dusky; the ventral pale; pectorals grayish, with no marking.
Length of body 220 mm.
Described from a specimen from Taihoku, collected by Oshima in October, 1916.
Habitat: Widely distributed throughout the Island. My specimens came from Taihoku, Raupi, Giran; Tozen River; -Nanshisho, Giran.
| Locality | Taihoku | Taihoku | Raupi |
| Head | 3 | 2.83 | 3 |
| Depth | 5.33 | 5.50 | 5.11 |
| D. | 44 | 41 | 44 |
| A. | 28 | 25 | 27 |
| P. | 16 | 15 | 16 |
| V. | 4 | 4 | 4 |
| Width of head | 2 | 2.2 | 2 |
| Interorbital | 5 | 4.66 | 5.3 |
| Snout | 6 | 6.33 | 5.60 |
| Eye | 8 | 8.25 | 7.33 |
| Scales | 4-57-14 | 4-54-14 | 5-56-14 |
| Length Min. | 220 | 215 | 196 |
Body spindle-shaped, posterior part compressed; head broad, depressed; Snout rather short, obtusely rounded anteriorly, interorbital space flat; eyes small, superior, and exceedingly anterior, nostrils separated, the anterior in a short tube, on upper edge of maxillary, the posterior in front of eye above; mouth oblique, large, its, angle extending beyond the posterior margin of orbit; maxillary 3 in head; mandible 2.66; lower jaw slightly longer than the upper; a row, of large caniniform teeth on palatine and inner side of lower jaw, a band of small teeth on outer edge of both jaws.
Color in formalin dark bluish gray above, paler below; belly dusky; eight large dark gray blotches above the lateral fine, extending anteriorly to the middle of and beneath the upward curve of the lateral line, forming a more or less continued longitudinal band; below this. another row of about fourteen similarly colored, large, irregular blotches, extending from the base of pectoral posteriorly to the base of caudal, running below the lateral line; interspace between the upper row of markings and the base of dorsal irregularly mottled with dark; upper surface of the head uniformly bluish gray, lower parts paler; a dark brown band from the upper -posterior corner of the orbit running backward, entering the upper row of markings of the. sides; below this is an irregular, more or less undulating streak of the same color from eye to middle of base of the pectoral; upper part of the dorsal, grayish, paler below, its membrane with a series of dark spots alongthe base; caudal fin uniformly gray, with a faint stripe near the base; anal fin gray, with indications of dark blotches I at the posterior half of the base; ventral fins whitish, rays dusky; the pectoral gray.
Length of body 285 mm.
Described from a specimen from Wodensho, Taichu, collected by T. Aoki in December, 1916.
Habitat: Wodensho, Taichu (a single specimen).
Remarks: The present species is easily distinguished from Ophicephalus tadianus by its lower body; the greater number of scales between orbit and posterior angle of pre-operculum; and, the greater number of scales in an oblique series between the lateral line and the root of ventral
Distribution: Ceylon; China; Formosa.
Body elongate, anterior part subcylindrical, compressed posteriorly; head rather broad, its top depressed; snout short, obtusely rounded anteriorly; mouth large, oblique, its angle extending beyond the posterior margin of orbit; lower jaw slightly longer than upper; teeth in both jaws and on vomer, cardiform; eyes moderate, superior, and much anterior; nostrils widely separated, the anterior in a long tube, just behind the upper lip, the posterior in front of eye.
Dorsal fin elongate, beginning overthe base of pectoral, the rays quite uniform in length, when depressed reaching beyond the root of caudal; anal fin similar to dorsal but shorter, beginning beneath the fifteenth dorsal ray and ending under the forty-second; rays of the dorsal and anal all unbranched; pectoral fin broad, not reaching the vent; no ventral fins; caudal fin broad and rounded; caudal peduncle short and deep, greatly compressed.
Lateral line broken anteriorly, running along the middle of the sides from the base of caudal to just above second anal ray, thence upward one row for one scale, again upward for one row, extending forward on seven scales, thence dropping one row, reaching to the upper extremity of gill-opening; body covered with large cycloid scales with irregular concentric lines and radiating striae; head and cheeks covered with plate-like scales.
Color in formalin yellowish brown above, paler below; the sides with about nine V-shaped dark cross-bars, the apex pointing forward, these markings clearer posteriorly and more or less broken and irregular in front; a large round black spot, bordered by white, on caudal peduncle near the base of caudal fin; sides of head with two broad, dark streaks from eye to the posterior edge of operculum, more or less undulating; dorsal and anal fins uniformly dusky gray, their edge somewhat darker; other fins grayish white.
| Locality | Taihoku | Taihoku |
| Head | 3.40 | 3.64 |
| Depth | 5 | 5.50 |
| D. | 44 | 45 |
| A. | 27 | 28 |
| P. | 14 | 15 |
| Width of head | 1.60 | 1.57 |
| Interorbital | 3.5 | 3.5 |
| Snout | 5 | 4.5 |
| Eye | 7 | 6.86 |
| Scales | 5-54-13 | 5-53-13 |
| Length Min. | 210 | 200 |
Length of body 210 mm.
The present description is from a specimen from Taihoku, collected by Oshima in September, 1916.
Habitat: Taihoku; Shori, Toyen; Tamusui River; Jitsugetsutan (Lake Candidius). One of the commonest fishes in ponds and stagnant pools.
Remarks: This species is very closely allied to Channa ocellata from China. It differs in having no teeth on palatines and a greater number of scales in a transverse series. 1
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Ot the seventy-six species above enumerated the following twenty-nine are artificially introduced species or semi-marine fished or species which have been collected in an outlying island, and therefore have no bearing on the problems of the geographical distribution of the Formosan fresh-water fishes. [ ... ]
On the remaining forty-seven species twenty-six (55%) are peculiar to the island.
At present the percentage of pectiliar species is extraordinarily high. But it is quite possible that some of them may be found in adjacent regions, probably in Southern China, and sooner or later a slight reduction may have to made.
[ ... ]. But the majority of the fishes which belong to these genera are distributed in British India, Indo-China, and China. Therefore, there is no doubt with reference to their relationship with the continental forms.
| Formosan species | Nearest relatives |
| Channa formosana | Channa ocellata from China. |
Not only such a relationship is manifested by the peculiar species, but by the rest of the fresh-water fishes as well. Of the twenty-one species, which occur outside of Formosa, Clarias fuscus , Capoeta semifasciolata , Distaechodon tumirostris , Culter brevicauda , Cultriculus kneri , Ophicephalis tadianus , and Ophicephalus maculatus are species of southern affinities, because they are distributed in Indo-China and South China, butnot to the north of the Yang-tze-kiang. Polvacanthus is a genus of the Indo-Malayan type, extending into the Malay Archipelago, but not occuring in eastern Asia. Such being the case, Polyacanthus operculatus may be included in this category, though it has been recorded from Tien-tsin, North China.
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It will thus be seen that all the Formosan fresh-water fishes which have Chinese affiRities differentiate into more or less distinct species, while those of southern affinities have remained unchanged. Moreover, eight per cent of the non-peculiar species have been recorded from the Chinese mainland. These two facts explain very clearly that the island had been preoccupied by the fresh-water fishes of the Chinese fauna when those of the southern affinities appeared through South China.
Next to the prevalence of Chinese affinities, the total absence of any indication of affinity to the fresh-water fish fauna of the Philippine Islands and Malay Archipelago is a very striking fact. As shown in the table, only oue species is recorded from the Philippines, namely Ophicephalus maculatus . However, as it also occurs in South China, its way of dispersal is clearly indicated, though there is no record of it in India and the Malay Archipelago. Cyprinus carpio is another species which has been recorded from Java. But it is evident that the carp is not a native of Java, but an introduced species.
| Ophicephalus tadianus | Ophicephalus maculatus | Channa formosana | |
| British India | - | - | - |
| Burma | - | - | - |
| Siam | - | - | - |
| Malay Peninsula | - | - | - |
| Indo-China | X | - | - |
| Hainan | - | - | - |
| Formosa | X | X | X |
| South China | - | X | - |
| North China | - | - | - |
| Corea | - | - | - |
| Amur Province | - | - | - |
| Japan | - | - | - |
| Sumatra | - | - | - |
| Java | - | - | - |
| Celebes | - | - | - |
| Borneo | - | - | - |
| Phillipine Islands | - | X | - |
According to Leonhard Stejneger, there exists the same relationship between Formosa and the Philippine Islands with regard to the herpetological fauna. He states that «A number of wide-ranging Species. of southern origin occur in both faunas, but as these also occur in southern China, on the mainland opposite Formosa, their way of dispersal is clearly indicated. There are only two species of this category which have not yet been collected in Chinese territories, namely, Dasia smaragdina, of wide distribution, and which may owe its occurence in Formosa to introduction by human agency, the other being a snake, Psammodynastes pulverulentus, the discovery of which within the limits of China would not cause surprise, as its known istribution includes Sikkim, Assam, and the Shan states.» (Proc. U.S. Nat. MUS., XXXVIII, 1911, pp. 93-94). Finally he has expressed his belief that there has been no direct land connection between Formosa and the Philippine Islands since Formosa received its batrachians and reptiles, because of the total absence of the Formosan herpetological fauna in the latter. The case of the fresh-water fishes is. quite the same. Therefore it is reasonable to support his view -with reference to the relationship between Formosa and the Philippine Islands.
On the contrary, the occurence of all Japanese species in the mainland opposite to Japan is another interesting fact. There seems to be good reason for asserting the prehistoric land connection between Japan proper and the Asiatic continent, though the relationship between Japan and Formosa is somewhat dubious on account of the total absence of fresh-water fishes in the Riu Kiu Islands which cover the interspace between the two.
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1 Channa ocellata is a synonym for Channa asiatica (Linné, 1758) . So is Channa formosana . [snakeheads.org]. Back
This passage was originally published under the above title in: Annals of the Carnegie Museum . No. 97, Vol. 12., pp. 169-328, in the year 1919.
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