“Ph. (Scleroconcha) Appellöfi* n. sp.
*This species is named after my esteemed teacher, Professor A. Appellöf.
Description: — Female:
Shell: — Length, 3.3-3.6 mm.; length : height about 1.5 : 1; length : breadth about 2:1. Seen from the side it varies, though only slightly, in shape. It is somewhat sub-rhomboidal with its greatest height at about the middle. The dorsal and ventral margins are boldly arched. The former is somewhat irregular, its posterior part is sometimes more flattened than is shown in the accompanying figure and with a distinct corner marked off from the posterior margin of the shell. The ventral margin is uniformly curved, passing without any corner into the posterior margin of the shell. The posterior part of the shell is drawn out into a strongly projecting, rounded beak-like process somewhat ventrally of half the height of the shell. The rostrum has a strongly projecting, rounded anterior corner; when the shell is seen from the side, the ventral margin of the rostrum is covered by a strongly projecting, powerful process, somewhat rounded distally. The incisur is broad, almost rectangular and is marked off from the ventral margin of the shell by a rather large and somewhat bifurcated protuberance. Seen from beneath the shell has almost parallel sides anteriorly and posteriorly converging irregularly and suddenly towards the anterior and posterior points. The surface of the shell has a powerful, decorative sculpture: partly four strongly projecting longitudinal ridges, and also numerous irregular foveolae of moderate depth size, situated close together. Of the four ridges two, one dorsal one and one ventral one, run close to the margin of the shell, which they cover to a great extent when the shell is seen from the side; the dorsal one splits about half-way along the shell into two ridges running close to each other and almost parallel, both continuing down to the rostrum. The two other ridges run more parallel to the longitudinal axis of the shell, one somewhat above, the other somewhat below half the height of the shell. The former continues anteriorly to the rostrum, where in most cases it joins the dorsal ridge; posteriorly it joins the ridge that runs along the ventral margin on the posterior beak-like process of the shell; the anterior part of this ridge is weakly and fairly uniformly curved dorsally; behind the middle of the shell, on the other hand, it is very irregular with at least two very striking, nodose, projecting corners. The latter, the ventral one of the ridges that run more parallel to the longitudinal axis of the shell, is almost straight and suddenly comes to an end posteriorly a short distance in front of the posterior beak of the shell with a rather strongly projecting protuberance; anteriorly just behind the rostral incisur it is joined by means of a low but distinct transverse ridge both to the ridge running most dorsally to it and to the ridge that runs along the ventral margin. The foveolae are sometimes considerably less developed than is shown in the accompanying figure. The rides, like the bottoms of the foveolae, have a sculpture with small cavities, sometimes very difficult to observe (in some cases not even existing?). The surface of the shell is sparsely furnished with small hairs, more numerous and somewhat longer near the margin of the shell. Pores of the surface are found to a moderate number; they are small and difficult to observe. Seen from inside the posterior beak-like process appears to be slightly hollowed out in the shape of a siphon. Medial bristles: The row of bristles on the rostrum is rather sparse; a number of bristles in this row do not seem to have any long distal secondary bristles. The bristles on the posterior portion of the list are difficult to observe with certainty; they seem to exist in moderate number and not to be arranged in clear groups. Between the list and the posterior margin of the shell no bristles seem to occur, nor is any pocket-like formation observable here.
First antenna: — Of the three bristles on the second joint the posterior one is the longest, being in most cases about as long as the total length of the third to the fifth or the third to the sixth joints; the lateral one is the shortest, in most cases about as long as the total length of the third and fourth joints. The third joint has two anterior bristles and on oh the first joint are all of about the same type, with one or more wreaths of long, stiff secondary bristles at the middle and short, fine hairs distally. Three of these bristles are subequal, somewhat longer than the anterior side of the second endopodite joint; the fourth is somewhat shorter. Second joint: The proximo-anterior group of bristles contains four bristles, the inner one of which is rather short and rather posterior bristle. Of the two anterior ones, which are situated somewhat distally of the middle of the joint, the anterior one is often somewhat longer than the other and about as long as the total length of the third and fourth joints. The posterior bristle on this joint is in most cases about as long as the shorter of the two anterior ones. The fourth joint has two anterior and four posterior bristles. The latter are of about the same relative length as in Ph. (Ph.) globosa; the two anterior ones are in most cases about as long as or somewhat longer than the two anterior bristles on the preceding joint. The bristle on the fifth joint and the a-bristle on the end joint are subequal, their length being about the same as the total length of the fourth and fifth or the fourth to the sixth joints. The length of the bristles discussed so far varies somewhat, though only slightly; their equipment is usually two to four irregular wreaths of long, stiff secondary bristles. The sensory bristles on the end joint have the following equipment: the b-bristle has two proximal and three distal sensorial filaments; the c-bristles have seven proximal and four distal sensorial filaments; the f- and -bristles have six proximal and four distal sensorial filaments. Pilosity: The second to the fifth joints have rather abundant transverse groups of short, stiff hairs.
Second antenna: — Exopodite: This is very like that of Ph. (Ph.) globosa. The proportion between the length of the first joint and the length of all the succeeding joints is about the same as in Ph. (Ph.) Lilljeborgi. The bristles on the second to the fourth joints are about as long as the two to three proximal joints, bare, and finish distally as two short, fine points. In females with large eggs in the brood chamber the long natatory bristles are broken off in the same way as in Ph. (Ph.) globosa. There are no basal spines, but a number of hairs in the distal rows of hairs on the second to eighth joints are considerably strengthened and are like spines at the place where in other species the basal spine is to be found. Endopodite: The first joint is very similar to that of Ph. (Ph.) globosa. The second joint is rather short; ventrally it has only one bristle, situated somewhat proximally of the middle of the joint. This bristle has numerous wreaths of long, stiff secondary bristles at the middle and short hairs distally and is exceedingly long, almost as long as the protopodite of this antenna. In one specimen (the type-specimen) there was observed on the antenna of one side, somewhat distally of this bristle, an additional bristle of about the same length and type as the bristles on the first joint. The distal bristle of the second joint is about as long as or somewhat shorter than this joint; it is rather pointed distally.
Mandible: — Protopodite: The basale has ventrally ten to twelve, usually ten, bristles of different lengths, some moderately long, some, especially among the distal ones, rather long. Dorsally this joint has, apart from the two distal bristles, only one bristle, situated somewhat in front of the middle of the joint; the latter bristle is about as long as this joint, the two distal bristles differ somewhat in length, the longest being about as long as the dorsal side of this joint or even somewhat longer; these bristles have one or a few wreaths, of long, stiff bristles at the middle and fine, short hairs distally; sometimes the proximo-dorsal bristle has no wreath. The two bristles of the exopodite are of about the same type and length as the two distal bristles on the second protopodite joint, sometimes they are rather longer, sometimes a little shorter. Endopodite: The four ventral bristles coarsely pectinated; the one situated nearest this is somewhat longer and finely pectinated; the two others are considerably longer than the former ones, the lateral one, which is the longest, being almost as long as the posterior side of the joint; of the two latter ones the inner one has short hairs, the outer one has short hairs distally and usually a wreath of long, stiff secondary bristles at the middle. End joint: The longest middle claw is almost as long as the second endopodite joint. The anterior claw is in most cases somewhat longer than half the long middle claw. Pilosity: The second protopodite joint and the second endopodite joint have groups of short, stiff hairs on the inside; the first endopodite joint has a row of similar hairs distally-anteriorly.
Maxilla: — This is very like the corresponding appendage in Ph. (Ph.) globosa. Protopodite: First endite: This has eleven distal bristles; in one specimen as many as twelve were observed on the maxilla of one side, on another only nine, but in the latter case it seemed probable that one or more bristles had been broken off. The extra bristle was placed close to the short one and was somewhat shorter and weaker than the powerful bristles; it had a wreath of long, stiff secondary bristles at the middle and was fairly strongly pectinated distally. In the case of twelve bristles the two extra bristles were of the type just described. Second endite see fig. 13. The third endite has nine bristles. As in Ph. (Ph.) globosa, the equipment of the bristles, especially the distal ones, and the number and strength of the secondary teeth are subject to variation. The bristle on the anterior side of the palp at the boundary between the protopodite and the endopodite is very short and almost bare. Exopodite: The equipment of the three bristles varies; one of the long ones often has no long secondary bristles. Endopodite: End joint: This has usually three a-bristles and three or four, usually three, c-bristles; the powerful b- and d-bristles are almost bare.
Fifth limb: — This is very like the type described for Ph. ( Ph.) globosa. Protopodite: First endite: The anterior and the posterior bristle are in most cases somewhat shorter than in the species just mentioned and have no long secondary bristles. The second endite has only seven, the third only eleven bristles. Exopodite: The anterior constituent tooth of the main tooth, like the tooth-like protuberance situated at its base, is less clumsy than in the species mentioned. The bristles on the anterior and posterior edges of the main tooth are subequal and of moderate length .and strength; there is sometimes a wreath of long, stiff secondary bristles at the middle of all three; sometimes the bristle situated behind the main tooth has no such wreath. Second joint: One of the outer bristles in the group of three bristles is relatively long, being about two-thirds or three-quarters of the length of the long middle bristle. Third joint: Of the two bristles on the outer lobe one is relatively short and weak, being only about half as long as the other. The shorter of these two bristles has a few long, stiff secondary bristles at the middle, the other has a few wreaths of similar bristles. In one specimen four bristles were observed on the inner lobe of this joint on the limb of one side.
Sixth limb: — This is very like that of Ph. (Ph.) globosa. We may add: Of the two medial bristles on the first endite of the protopodite one is short, the other usually moderately long. The endite on the first joint of the exopodite has one or two medial bristles and from eight to ten distal bristles. The second exopodite joint has 32-36 bristles distally.
Seventh limb: — This is about half the length of the shell. The cleaning bristles are comparatively few in number, only ten to twelve being observed; of these three dorsal ones and three ventral ones are placed closely together distally, and from four to six, two or three on each side, are scattered somewhat proximally of the former ones. Some of the distal bristles are rather long, the others are of moderate and somewhat varying length. On the long bristles there are about six to ten, on the shorter ones two to six, bells cut off transversally distally; the tongue of the distal bell is also cut off transversally distally. Proximally of the bells the cleaning bristles are furnished along the greater part of their length with dense, short, fine, stiff hairs, arranged into from about two to five wreaths. The end comb is rather weak and consists of about seven or eight subequal teeth of moderate length. These teeth are rounded distally and are furnished on both sides with from one to three weak secondary teeth. The cavity dorsally of the end comb is shallow, furnished at about the middle with a chitinous peg of about the same type and size as the teeth of the end comb.
Furca: — This has from thirteen to fifteen claws; sometimes the same number is found on both lamellae, somtimes it is different; the combinations 15-15, 15-14 and 15-13 were observed. Claws nos. 1, 2 and 4 are powerful, claw no. 3 is somewhat shorter and rather considerably weaker than no. 4. From claw no. 5, which is pretty considerably shorter and weaker than no. 4, the following claws decrease fairly uniformly in length and strength the more posteriorly they are situated. On claw no. 3 the secondary teeth extend in most cases right to the point. On the two distal claws there is basally-medially a group of rather long, stiff bristles; these bristles are in most cases rather weakly developed and sometimes seem even to be missing on claw no. 2. On the following claws there are no such bristles at all. On the inside of the furcal lamellae there is at the base of the claws a rather abundant supply of fairly long, stiff bristles varying in length, in most cases without any evident arrangement in groups. In addition there are at this part copious short, fine hairs more or less clearly arranged in groups of something like rows; behind the claws the lamellae have fine hairs. The pilosity is subject to variation.
The length of the rod-shaped organ is about 0.7 mm.; its proximal two-thirds is segmented; distally it is either finely pointed or rounded. It has sparse, short, scattered hairs.
The male is unknown.
Habitat: —South Georgia: S.A.E., Station 20, Antarctic Bay, lat. 54° 12' S.. long. 36° 50' W.; 6. V. 1902; depth, 250 m.; small stones; R.M.S. 139. S.A.E., Station V, off May Bay, lat. 54°17' S., long. 36°28' W. (type locality); 14. V. 1902; depth, 75 m.; clay with scattered algae; temperature at the bottom, + 1.5° C; R.M.S. 140. S.A.E., Station 24, off Grytviken, lat. 54°22' S., long. 36°27' W.; 20. V. 1902; depth, 95 m.; clay; R.M.S. 14 S.A.E., Station 30, Moran Fiord, lat. 54°24' S., long. 36°26' W.; 26. V. 1902; depth, 125 M.; clay with scattered stones; temperature at the bottom, — 0.25° C; R.M.S. 142. At these stations twenty or thirty specimens were captured in all, mature females and juvenes in different stages.
S.A.E., Station 6, S.W. of Snow Hill Island, lat. 64° 36' S., long. 57° 42' W.; 20. I.1902; depth 125 m.; stones and gravel: one specimen, a larva, presumably belonging to this species was captured; unfortunately it was too young for certainty of identification; R.M.S. 143'
Type-specimen on slides in the collections of the R.M.S.” (Skogsberg 1920, p.419-429)
Scleroconcha appelloefi is een mosselkreeftjessoort uit de familie van de Philomedidae.[1] De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1920 door Skogsberg.
Bronnen, noten en/of referenties
