“Amphiporus spinosus, Burger, 1893 (Plate XVI, fig. 22; Figs. 44, 45).
A. spinosissimus, Burger, 1893 ; A. cruciatus, Burger, 1893 ; A. multihastatus, Joubin, 1914.
This species could nearly always be found in kelp roots. Three types were originally described under N 3, N 16, N 20, the different sizes, number of eyespots, colour and states of contraction leading to confusion. The length and breadth vary from 25 and 0.8 mm. to 180 and 2.8 mm., though the majority are shorter and broader than the
latter.
The body is round, tapering at the posterior end. The snout is broadly acute. There may be no distinction between head and body, or the head may be broader than the broadest part of the body (in the smaller specimens) and two partial lateral furrows may be present, almost vertical in direction, with a chevron groove behind the head. This groove is complete ventrally. Sometimes the aperture of the rhynchodaeum can be seen. The colour is pale pink, pinkish red, brick red, orange or light orange red, usually deeper on the back and anteriorly. Sometimes the underside of the body is much paler than the back. There are two groups of eyespots on each side, often appearing as vague blackish
patches.
Form and colour of preserved specimens. The lengths and breadths of a number of specimens are as follows : 51.0, 5.0 mm.; 31.0, 3.2 mm.; 60.0, 4.5 mm.; 85.0, 4.5 mm.; 14.0, 1.8 mm. ; 32.0, 1.8 mm.; 130.0, 3.5 mm.
The body is round in section, the head blunt and the tail acute. The head is usually marked off from the body by a distinct and almost complete annular groove; dorsally this groove forms a wide V with the apex pointing back (Fig. 44). Anterior to this there are often lateral grooves, as in Fig. 44, and sometimes a median vertical groove in which can be seen the openings of the head gland and rhynchodaeum. The eyes are not all visible unless the specimen is cleared. On clearing two groups of brown cup-shaped eyespots can be determined on each side. The eyes vary from fifty or so in each group to small numbers like seven in the anterior and four in the posterior group of one side. They appear to increase with the size of the worm. The anterior eyes open forwards, the posterior more to the side, and they vary in size. The colour is usually bleached, but sometimes a faint general pinkish tinge is observed.
Anatomy. The head glands open at the tip of the head. There is a main compact dorsal strand which is joined by a smaller ventral strand under the vascular loop just anterior to the opening of the rhynchodaeum (Fig. 45A). The dorsal strand becomes thin and scattered posteriorly and does not extend to the brain. The ventral strand forms an investment to the rhynchodaeum on each side and continues back past the junction with the oesophagus. It, too, disappears before the brain.
The epithelium is very thick. In places it is thicker than basement membrane, circular muscles and longitudinal muscles put together. The basement membrane itself is thick and stains strongly. In the head, at about the level of the cerebral organs, there are eosinophile glands in the longitudinal layer whose ducts pass through the circular layer and basement membrane. These are not seen farther down the body.
The oesophagus is at first thin and small. It expands in the region of the brain into the stomach. Far back there is an anterior caecum with two short forward branches. The vascular system is normal and the excretory tubules occur just posterior to the brain.
The proboscis as far as the armature is almost half the length of the body. The accessory armature and proboscidial nerves vary greatly, though there is always a main stylet mounted on a brownish pear-shaped base (Fig. 45B). The following range of variation has been found:
Serial No.
Length of worm, mm.
Accessory reservoirs
Number of stylets in each reservoir
Number of nerves
N 16
60.0
18
1
--
N 16
90.0
18
1 (2)
14
N 20
14.0
7
1 (2) (3)
--
N 20
32.0
2
3
--
N 20
11.0
6
1
11
N 20
30.0
8
2 (3)
--
N 3
130.0
12
2 (3)
17
--
65.0
14
2 (3)
--
--
60.0
13
2 (1)
--
--
38.0
9
2 (1)
--
--
30.0
8
2 (3)
--
N 3
--
7
--
17
N 3
62.0
18
2 (1)
15
N 3
--
12
2 (1)
15
N 3
--
11
2
15
N 3
--
16
2 (1)
17
N 16
92.0
22
1 (2)
18
N 20
--
5
--
--
N 3
--
--
--
16
N 110
75.0
13
2 (1)
19
N 121
45.0
22
1
--
--
27.0
10
2 (1)
17
N 131
50.0
--
--
17
N 135
95.0
--
--
26
N 136
27.0
13
--
16
It seems evident that no specific value can be given either to the armature or to the proboscidial nerves. There is a possibility of increase with size or age.
The brain is fairly large but does not show any peculiarity. In one series of sections the lateral nerves left the brain by a sharp twist outwards, but this is merely the effect of contraction. The cerebral organs open by two very small pores ventro-laterally behind the opening of the rhynchodaeum. The organs are small and do not reach the brain.
Some of the specimens were males, some females. The gonads are shed laterally both above and below the nerves (Fig. 45D). Eggs were ripe in November and December.
In view of the extreme variation in the accessory armature and proboscis nerves the distinctions that have been drawn on these characters cannot hold. I therefore feel justified in bringing together the species described by Burger and Joubin under A. spinosus, Burger.
In addition to the collection from King Edward Cove this species was taken at the following stations:
St. 39. 25. iii. 26. OTL, 179-235 m.
St. 45. 6. iv. 26. OTL, 238-270 m.
St. 123. 15. xii. 26. OTL, 230-250 m.
St. 140. 23. xii. 26. OTL, 122-136 m.
St. WS 56. 14. i. 27. NH, 2 m.
St. WS 62. 19. i. 27. BTS, 26-83 m.
St. WS 65. 22. i. 27. Sh. coll.
St. WS 73. 6. iii. 27. OTC, 121-130 m.
St. MS 68. 2. iii. 26. NRL, 220-247 m.
St. MS 71. 9. iii. 26. BTS, 110-60 m.”
(Wheeler, 1934; 266-269)
