11/14/99 translated by M. Toyokawa Two species of bathypelagic siphonophore genus Bathyphysa "Magatama-Nira" Tamiji Kawamura (Laboratory of Zoology, Faculty of Science, Kyoto University) There have been six species of Bathyphysa, namely : 1) Bathyphysa abyssorum Studer, 1878. Obtained by a submarine cable-laying boat "Faraday" in the N. Atlantic Ocean (depth : 1780 and 1000 fathoms). A single siphon and a single gonodendron clusted to a piece of the stem. 2) B. grandis Fewkes, 1886. From the Gulf Stream in the N. Atlanlic Ocean (depth : 3458 meter). Later the "Siboga" brought another specimen supposed to be indentical to this. This species was transferred to genus Pterophysa by Lens and Rlemsdljk (1908). 3) B. gtgantea Haeckel, 1888. Recorded after a piece of the bract from the S. Atlantic. No illustration was given and it is uncertain what it was. 4) B. grimaldii Bedot, 1893. Captured five times by the "l'Hirondelle" in 1888 at the west of Azores (depth : minimum 1372 fathoms) maximum 2000 fathoms. Also obtained by the "Princesse Alice" eight times in the voyage between years 1892 and 1902 (depth : minimum 924 m., maximum 5440 m.). However, even the best specimen was mere an upper portion of the colony with a pneumatophore and a few siphons. 5) B. sibogae Lens and Riemsdijk '08. Caught by the "Siboga" at south of Borneo (depth 521 m.) and east of Celebes (depth 2081 m.). A piece of the stem with a few tentacles and siphons. The illustration is unclear. 6) B. sp. Bigelow' 11. Obtained from the Tropical Pacific Ocean three times by the "Albatross" in her voyage during 1904-1905 (depth : 300 f., 300 f. and 800 f. respectively). All specimens were too poor to be identified. A few years ago, the author examined the specimen deposited in the Bilogical Station of the Imperial Palace, and I have found that a new species occur in Sagami Bay. After that, the author happened to detect a perfect specimen of a known species, B. grimaldii, at the collection room of the Mitsui Marine Biological Laboratory. I have presented a preliminary report (published in the Zoological Magazine of Japan, Vol.55, No. 2) at the 17th meeting of the Japanese Association of Zoology in October 1942. This genus was supposed, by the European and American researchers, to be closely related to the genus Rhizophysa because of the structure of the pneumatophore, but to belong to another family because of the morphology of the siphons. However, the structure of cormidium, especially the state of gonodendron, had been totally unknown. It became completely clear by these two specimens. I. Bathyphysa grimaldii Bedot, 1893 Magatama-Nira (figs, 1-5) Collection date is unkown. It was announced that the specimen was collected off Heta in the Suruga Bay. The author borrowed and carried this specimen to Kyoto in December 1941, and it is now kept at the Laboratory of Zoology, Kyoto Imperial University. The specimen is, because the stem highly contorted and twisted, entangled like a tangled pieces of thread, especially so at the posterior part. However, the number of gastrozooids amounted to dozens and the gonodendra well developed. It is really a perfect specimen. Although it is regrettable that the photographs cannot be shown here (it will be shown in the report in English), it measures in whole length more than 40 cm when streching the entangled stem to nearly straight in the water. Besides the stem, the zooids, which dettached from the stem and was found in the bottle, were 36 siphons (of which 23 were bladder form, 13 were hook-shaped) and 4 gonodendra. Each of them are described below. A) The pneumatophore is 20 mm. in height, 6 mm. in maximum breadth and spindle-shaped, with some faded reddish brown pigments near the apex. It is opaque pelucid, and the absence of hypocystic villi in the interior is a character distinguishing this from Rhyzophysa. B) The breadth of the stem differs here and there according to the degree of the contraction of the stem. At the thickest portion it measures more than 3 mm. in diameter. On the upper end of the stem immediately below the pneumatophore, there is a budding zone where many young zooids attach in line. Next to this part, there is a part where bladder-form siphons (described later) cluster densely, and at lower zones gonodendra gather (fig. 1 shows these parts) and then the hook-shaped siphons grow in crowds. The most remarkable fact is that the stem branches, and it obviously branches off once at the portion where many gonodendra attach to. Such branching may occur in the lower part, but is hard to confirm on account of the strong contortion of the colony. C) The siphons are modified or deformed secondarily into various types : 1) The most unmodified form is clearly composed of the three portions, i.e. a long slender pedicular portion, an inflated gastric portion, and a well musculated proboscis with a distal aparture extended like a trumpet. The gastric portion is curved at the middle and take the shape of a fishing hook. A thin membrane is stretched to enclose both sides of the siphon, and a gas bubble is kept inside (fig. 2). 2) On the contrary, in the most modified form, the pedicular portion shortened or disappeared, the terminal proboscis has no muscle layer and no aparture, while the gastric portion bends in kidney shape, and there are thin membranes on both side to form perfectly airbladder-like structure, embracing a gas bubble in their interior (fig. 3).@3) Some siphons situated rather lower part of the stem take a form that shows some transitory stages of the above two, the bladder-like form with a short pedicle or a distal aperture. 4) Among them there are some forms in which two siphons united together to form cocoon-shape or three siphons united (fig. 4). The dimension of these siphons varies, for instance the kidney-shaped pneumatosiphon has its longer diameter changing from 10 to 18 mm. D) The tentacle is a simple cylindrical string, the simplest of siphonophores., 0.5 to 1 mm. in diameter. It seems to be generally short, although it is contracted, and its arrangement on the stem seems to be irregular. E) The gonodendron is very similar in construction with that of Physalia and Rhizophysa. It is composed of 10-20 gonophores, with a single gonopalpon and a medusoid appendage (fig. 5). Numerous gonophores cluster in oval or spindle-shaped (or cylindrical when young) form, and are attached irregularly to the surface of the ventral side of the stem (not arranged regularly as in Rhizophysa.), and are more mature in lower portion. It is a conspicuous character of this species that, these gonodendra cluster next to the portion, where bladder-like siphons attach densely, from the apical end of the stem, and are not found at lower part. There is no doubt that this species is Bathyphysa grimaltdii from the character of siphons and other points. II. Bathyphysa japonica Kawamura '43 Ko-Magatama-Nira (figs. 6, 7) Type specimen - deposited in the Bilogical Station of the Imperial Palace. On this specimen, the state in the living condition is recorded in detail. This is the shallowest record for Bathyphysa ever reported. Presumably it had been carried by current from offshore, as many warm-current living plankton were observed on the sea surface at the same time. Living condition - It is announced that when caught, the length of the stem reached 3 m., but the lowest part of the colony was cut and remained in the water. The entire colony was colourless and pelucid exept that the apex of the pneumatophore was ornamented with reddish brown pigments, the interior of the siphon green, the distal aperture yellowish green in tint. At present in preserved condition, below the apical pneumatophore there is a stem which branches two (or three ?) times, and it measures in whole length about 23 cm. with the pneumatophore when measured in the longest branch. The morphology of zooids is described below. A) The pneumatophore is 18 mm. in length, 6 mm. in maximum breadth and spindle-shaped. It is coulourless and pelucid except that there are reddish brown pigments at the apex. There is no hypocystic villi. B) On the ventral side of the stem just below the apical pneumatophore, there is a budding zone. On the right side of the stem young tentacles cluster in line, and to the right of them young siphons cluster in line. Soon below the budding zone the first branching occurs (fig. 6), while the broader stem is cut there, in the narrower stem the second branching occurs about 20 mm. below. Besides these there is a stem presumably the third branching about 50 mm. over the end of the stem, but it is a little unclear as the branch is cut immediately below the point. C) Eleven siphons is all have been left, of which five are hook-shaped gastrozoid with a distal aperture and a long pedicle, the other six are kidney-shaped i.e. bladder-shaped and are at all in the form of pneumatosiphon. However, on the contrary to the former species, the hook-shaped siphons attach more apical portion than the bladder-shaped siphons. The third and fifth siphons from the lower end are two siphons united together to form cocoon-shape (fig. 7). D) The tentacle is a simple cylindrical string like the former species, and thinner and shorter than the former species. The arrangement is irregular and the number is small. E) The gonodendron is missing. It is presumably because of the season. This species is obviously distinguishable from the foregoing by its lesser dimension of every features , and form and the portion of attachment of the siphons. It does not agree with any hitherto known species. Conclusive discussion 1) By the study of the specimens of the two species in good condition, the characters of Bathyphysa has become clear, and the relationship with other genus was settled. 2) Lens and van Riemsdijk's classification of Pterophysa and Bathyphysa relying upon the absence of presence of the pedicle in the siphon is unreasonable. 3) The fact that the stem can branch gives a pronounced suggestion to the explanation of the structure which has been considered to be a difficult problem. It gives proof to the author's opinion that for example, a tentacle of "Baren-Kurage" Physophora or of "Yauraku-Kurage" Agalma should not be considered as a homologue of a tentacle on the margin of the manubrium of mudusa, but it is really a branch of the stem. Accordingly each clustering tentillum on it must be regarded as it corresponds to the ordinary zooid. 4) The possibility of union of more than two diffrent zooids is very important, too. It proves the author's long-discussed opinion that such a difficult problem, for instance, the tentacle in "Katsuwo-No-Eboshi" Physalia is not accompanied by a siphon as other Siphonophora, but attach at the base of a palpon must be regarded as a tentacle sometimes unite with a siphon and in other cases with a palpon. Accordingly, in "Ko-Bouzu-Nira" Rhizophysa fusiformis, it should be regarded as a siphon united with a gonodendron. 5) While in genus Rhizophysa the single apical pneumatophore serves as a float, in the present genus the branching of the stem rendered the colony complicated, so that it can be considered that the secondarily modified siphon serves as an accesary float. Explanation of the figures 1 Bathyphysa grimaldii. Upper 1/5 of the specimen. x1 2 Same. Hook-shaped siphon. x1 3 Bladder-like siphon. x1 4 Same as 3. United three siphons. 5 Gonodendron. x4 6 Bathyphysa japonica. Upper part of the specimen. x1 7 Same. Lower part. x1 Pn. Pneumatophore, St. Stem, Y. Branching point of the stem, T. Tentillum, Gd. Gonodendron, Si. Hook shaped siphon, Sp. Pneumatosiphon.