"Pseudechinus magellanicus (Philippi).
? Echinus margaritaceus. Lamarck. 1816. Hist. nat. anim. s. vert. III. p. 47. II. Ed. 1840.
III. p. 363.
? Echinus margaritaceus. Blainville. 1825. Dict. sc. nat. XXXVII. (Oursin), p. 78.
? Echinus margaritaceus. Valenciennes. 1846. In Du Petit-Thouars. Voyage de la Frégate
Vénus. Atlas. Zoophytes. Pl. VI. ı.
? Heliocidaris margaritacea. L. Agassiz & Desor. 1846. Cat. rais. des Echinides, p. 371.
Echinus magellanicus. Philippi. 1857. Vier neue Echinod. d. Chilenischen Meeres. Arch.
f. Naturgesch. 1857. p. 130.
Psammechinus magellanicus. Dujardin & Hupé. 1862. Hist. nat. Zooph. Echinod. p. 528.
Echinus magellanicus. A. Agassiz. 1872-74. Revision of the Echini, p. 123, 492.
Echinus magellanicus. A. Agassiz. 1874. Echinoidea of the Hassler Exped. p. 11, Pl. III.
5.
Echinus margaritaceus. A. Agassiz. Ibidem, Pl. III. 4.
Echinus magellanicus. Studer. 1880. Űbersicht d. “Gazelle” Echinoiden. Monatsber.
Akad. Berlin. 1880, p. 875.
Echinus margaritaceus. Studer. Ibidem. (var. Hassleri. Döderlein. Op. cit. 1906, p. 229).
Echinus magellanicus. Bell. 1881. Echinod. of the "Alert". P. Z. S. 1881, p. 90.
Echinus magellanicus. A. Agassiz. 1881. "Challenger" Ech. p. 116.
Echinus magellanicus. Rathbun. 1886. Cat. Echini U. S. Nat. Mus. Proc. U. S. Nat. Mus.
1886, p. 278.
Echinus magellanicus. Philippi. 1892. Űber die chilenischen Seeigel. Verhandl. d.
deutsch. wiss. Vereins. Santiago. Chile. II. p. 247.
Echinus magellanicus. Meissner. 1896. Die von Dr. Plate aus Chile heimgebr. Seeigel.
Arch. f. Naturgesch. 62. 1. p. 87.
Echinus fueginus. Philippi. 1898. Especies nuevas Para la fauna de Chile. Rev. Chilena
de storia natural. II. p. 88.
Echinus magellanicus. Meissner. 1900. Echinoiden d. Hamburg. Magalh. Sammelreise,
p. ıо.
Echinus magellanicus. Koehler. 1901. Echinides et Ophiures du S. Y. Belgica, p. 4.
Sterechinus magellanicus. Mortensen. 1903. "Ingolf" Ech. I. p. 103, 107, 177. Pl. XIX.
11, 17, 23.
Echinus magellanicus. de Loriol. 1904. Notes pour servir à l'ét. des Ech. 2. Sér. II. p. 13.
Pl. I. 7-9.
Echinus magellanicus. Koehler. 1906. Stéllérides, Ophiures et Echinides. Exped. Antarct.
Française (Charcot). p. 30.
Notechinus magellanicus. Döderlein. 1906. Echinoiden d. deutschen Tiefsee-Exped. p.
227. Taf. XXVII. 9; XXVIII. 3, 4; XXXV. 15; XLVII. 5.
Notechinus magellanicus, var. hassleri. Döderlein. Ibidem, p. 229.
Notechinus magellanicus, var. novae-amsterdamiae. Döderlein. Ibidem, p. 229.
Notechinus magellanicus. Mortensen. 1910. Echinoidea of the Swedish S. Polar Exped.
p. 36, Pl. XVI. 3, 6, 9-12, 19.
Echinus magellanicus. Jackson. 1912. Phylogeny of the Echini, p. 35, 40, 43, 119, Pl. 3.
14; p. 148, textfig. 165; p. 160.
Parechinus magellanicus. H. L. Clark. 1912. Hawaiian Ech. Pedinidæ … p. 275.
Pseudechinus magellanicus. H. L. Clark. 1925. Cat. Rec. Sea-Urchins Brit. Mus. p. 118.
Pseudechinus magellanicus. Lambert & Thiéry. 1925. Ess. nom. rais. p. 572.
Notechinus magellanicus. Bernasconi. 1925. Res. Prim. Exped. a Tierra del Fuego.
Equinodermos. I. Equinoideos. (An. Soc. Cient. Argentina. 99). p. 10 (254). Pl. II. 1-3.
Pseudechinus magellanicus. Tortonese. 1933. Gli Echinod. del Mus. Torino. I. Echinoidi.
Boll. Mus. Torino. XLIII. p. 122.
Pseudechinus magellanicus. Bernasconi. 1934. Los Equinodermos de los mares
argentinos. Bol. del Centro Naval. Buenos Aires. No. 506, p. 14, fig. 14.
Notechinus magellanicus. Mortensen. 1936. Echinoidea and Ophiuroidea. Discovery
Reports XII. p. 220.
Notechinus magellanicus. Mortensen. 1941. Echinoderms of Tristan da Cunha. Res.
Norweg. Sci. Exped. to Tristan da Cunha 1937-38. No. 7. p. 8.
Notechinus magellanicus. Bernasconi. 1941. Los Equinodermos. Exped. del bucque
oceanogr. “Comodore Rivadavia”. Physis. XIX. p. 44. Lam. ı. 3-4.
Non. Echinus magellanicus. Tenison-Woods. 1878. Echini of Australia. Proc. Linn. Soc.
N. S. W. II. p. 165. (? Nudechinus darnleyensis (Ten. Woods).
Echinus magellanicus. Farquhar. 1898. Echinod. Fauna of New Zealand. Proc. Linn.
Soc. N. S. W. XXIII. p. 320. (Pseudechinus albocinctus).
Echinus magellanicus. Hutton 1904. Index faunæ Novæ Zealandiæ, p. 289.
(Ps. albocinctus).
Notechinus magellanicus. var. neu-amsterdami. Koehler. 1908. Stellérides, Oph. et
Echinides. Exped. antarct. nat. Ecossaise (“Scotia”). Trans. R. Soc. Edinb. XLVI.
p. 616. (Ps. marionis).
A few papers simply enumerating the species magellanicus, giving no information about it, mined from the above list.
This species is so well known, particularly through the descriptions and illustrations given Loriol, Op. cit. 1904; Döderlein, Op. cit. 1906; and the present author, Op. cit. 1910, would be rather superfluous to describe it here again. Only a couple of figures illustrating _ structure are given (Fig. 125), mainly for comparison with the closely related New Zealand species, Ps. albocinctus; also a section of a spine (Fig. 126, a; p. 236). A few of the measurements from my work of 1910 are repeated here (p. 234), in order to introduce the percentage values apical system and peristome, which were not given in the said work.
The largest size recorded is 40 mm diameter. Very important is the fact that tubercles are usually fairly distinctly, though very finely crenulate.
It is an interesting fact that in the largest specimens the apical system may be distinctly larger than the peristome. Also the largest specimens have mostly two oculars insert, viz. Oc. I and II, or I and V, or even II and V; but the rule is that Oc. I alone is insert. Jackson finds
h. d.
v. d.
Apical system
Peristome
Number of plates
A. I. A.
38 mm
24 mm
12 mm (31.6 % h. d.)
11 mm (28.9 % h. d.)
25-26
19-20
37
27.5
12 (32.4 )
10 (27.0 )
24-25
18-19
36
22
12 (33.3 )
10 (27.8 )
24-25
17-18
36
20.5
10.5 (29.2 )
11.5 (32.0 )
23-24
18-19
30.5
16.5
10 (32.7 )
9.5 (31.2 )
21
15-16
26
14.5
8 (30.8 )
8.5 (32.7 )
19-20
14-15
25
15
7 (28.0 )
8 (32.0 )
20-21
16
24
14
7.5 (31.3 )
8 (33.3 )
20-2 1
16
23
13
7.5 (32.6 )
7.5 (32.6 )
21
16-17
22
14.5
7.2 (32.7 )
7 (31.8 )
20-21
16-17
21.5
13
6.5 (30.3 )
7.5 (34.9 )
20
15
21.5-
11.5
5.8 (27.0 )
8.5 (39.5 )
19
14-15
this to be the case in 88 %, “the highest percentage of ocular I only insert of any sea-urchin known” (Op. cit. 1912, p. 119). - The “radioles d’une finesse extrème et invisible à l’œil nu” found by de Loriol on the buccal plates, Op. cit. p. 15, are the stalks of pedicellariæ; spines do not occur on the buccal plates in any species of Pseudechinus.
The development is unknown.
A most extraordinary case of regeneration is seen in a young specimen, 5 mm diameter. from the Falkland Islands; in some way or other almost half of the test has been cut away, and the wound has healed up and spines are developing on the healed surface.
The var. Hassleri of Döderlein, Op. cit. 1906, is of little value and scarcely to be maintained as distinct (Mortensen, Op. cit. 1910, p. 41); H. L. Clark (Op. cit. 1912, p. 274), also expresses the same opinion.
The var. novæ-amsterdamice of Döderlein is more distinct and should perhaps rather be regarded as a separate species (cf. Mortensen, Op. cit. 1921, p. 159). It is distinguished from the typical magellanicus by the smaller apical system, the usually somewhat larger number plates, and by the shorter, greenish spines. - In these respects it more resembles Ps. novæ-zealandiæ, from which it differs, on the other hand, in the reddish colour of the test. (The “Notechinus magellanicus, var. neu-amsterdami” recorded by Koehler, Op. cit. 1908, from Gough Island, is Pseudechinus marionis, cf. p. 236).
Occurrence. Common all round the southern coasts of S. America, with the Falkland Islands, from the mouth of La Plata on the Atlantic to S. Chile (Puerto Montt) on the Pacific side. The record of its occurrence at Ancon, Peru (Rathbun, Op. cit. 1886) is hardly reliable, either the identification or the locality being not trustworthy. The same may apply to the loc. Valparaiso given in the Revision of the Echini, p. 123. The species is not mentioned in Clark’s Echinoderms of Peru, 1910. It is further known from Tristan da Cunha (Mortensen, Op. cit. 1941). But all the records of the occurrence of magellanicus at Gough Isl., Kerguelen, and off the Marion and neighbouring islands most probably rest on misidentifications (Pseudechinus malionis). The var. novæ-amsterdamiæ is known only from off New Amsterdam.
The bathymetrical distribution is from the littoral region to 820 metres; the latter depth is from the “Albatross” (H. L. Clark, Op. cit. 1912, p. 275). The greater depths, down to 2925 metres (1600 fathoms, “Challenger” St. 147) most probably refer to Pseudechinus marionis.
That the Echinus fueginus of Philippi (Op. cit. 1898) is identical with Ps. magellanicus seems beyond doubt; the poor description does not reveal any character of real value by which it could be distinguished from magellanicus. His Echinus Cumminghami, rodula, and lepidus (Op. cit. 1892) may likewise be magellanicus, but since they are only nomina nuda it does not matter much what they are.
As a synonym of Ps. magellanicus Agassiz (Rev. of Ech. p. 123) gives Psammechinus cupreus Troschel, a manuscript name which he had seen in the Museum of Frankfurt a. M. Döderlein (Op. cit. 1906, p. 227), who has examined the type specimen, states it to be Psammechinus microtuberculatus.
The great general resemblance between Ps. magellanicus and albocinctus has caused a good deal of confusion, the latter being taken by Agassiz (Rev. of Ech. p. 492) and after him by other authors, Hutton, Farquhar, Ramsay, to be identical with magellanicus, which was thus erroneously regarded as having a circumpolar distribution. Still H. L. Clark, Op. cit. 1912, p. 274, will at most concede to albocinctus the rank of a variety of magellanicus. Later on, Op. cit. 1925, he has, however, been convinced that they are two distinct species. The denuded tests of the two species are so much alike that the confusion of the two was quite excusable in the times when the characters of the test alone were taken into consideration for distinguishing species; there are some differences in the tuberculation, the tubercles being more numerous and somewhat smaller in magellanicus than in albocinctus (Figs. 125, a, b, to comp with figs. 120, a; 121, a), but I do not think it would be possible thereby alone to distinguish with certainty between the two. Also the number of the plates is essentially the same. But the apical system is conspicuously different in the two, much larger, c. 28-33 % h. d. in magellanicus than in albocinctus, c. 22-25% h. d.; then Oc. I is usually insert in magellanicus, exsert in albocinctus, and the suranal plate is naked in magellanicus, has a prominent tubercle in albocinctus. The peristome is, in contrast to the apical system, smaller, c. 27-33 % h. d. in magellanicus, larger, c. 35-37 % h. d. in albocinctus. Further magellanicus has two sorts of globiferous pedicellariæ, a large and a small one, the former with one or more lateral teeth to each side of the valves, albocinctus has only one kind of globiferous pedicellariæ, generally with only a single, unpaired lateral tooth. Finally the colour of the spines is conspicuously different, magellanicus never having the very beautiful dark reddish or purplish, white-tipped spines so characteristic of albocinctus. These differences make the distinctness of the two species indubitable; on the other hand, I agree that it is going too far to refer them to two different genera, albocinctus to Pseudechinus, magellanicus to Notechinus, the latter genus being not maintainable as distinct beside Pseudechinus (cf. above, p. 225).
I may recall that in my opinion Lamarck's Echinus margaritaceus was in reality the same as our magellanicus; but this cannot now be decided, and the name margaritaceus is to be dropped definitely." (author, date)
