Comprehensive Description

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Description

Graneledone antarctica, new species
Figures la–i, 2

 

 

Material studied: Holotype—male, mantle length 41 mm, from Ross Sea, Eltanin Sta. 2110, 74°05.6'S, 175°05.2'W in 2341 m with 10-foot Blake trawl, February 8, 1968, USNM 729679. Paratypes—male, mantle length 39 mm, female, mantle length 45 mm, UMML 1667. Male, mantle length 38 mm, 3 females, mantle length 25-41 mm, USNM 729680. ( All paratypes with same data as holotype.)

 

Description: The mantle is short, broadly rounded posteriorly, and very wide. It is distinctly flattened dorso-ventrally. The head is set off from the mantle by a slight constriction. The head is nearly as wide as the mantle, flattened, and bears large conspicuous eyes.

 

The funnel is of moderate size; it is free for its anterior half which is tubular and tapered. The funnel organ is VV-shaped but shows con­siderable variation ( Figs. la, b ). It is composed of 2 elongate oval pads slightly to moderately split anteriorly with pointed to blunt tips.

 

The arms are long and rather stout; the arm order is 1.2.3.4, either I or II always being the longest and IV always the shortest. The web is moderately deep with the formula C = B.D.A = E but showing some individual variation. The web extends only a short distance up the dorsal side of each arm after which there is no trace. On the ventral side of I, II, and III the web extends to the tip of the arm. It is low in the basal half but at about the midpoint of the arm it broadens, becoming widest at about the distal 1/5 of the arm. Only the extreme tip of the arm is free. On preservation, the contraction of the web curls the arm tip in a pronounced fashion. The arm web attains its greatest develop­ment on I and II. The suckers are small and in a single row on each arm. They are largest near the base of the arm and regularly decrease in size toward the arm tip.

 

The third right arm is hectocotylized in the male. It is bordered ventrally by a membrane or web, its outer margin thickened, cream-colored, and rolled outward. The contraction of this thickened border curls the arm tip downward resembling a hook or a slight S-curve. This shape is probably not found in the living animal but is due to the action of the preservative. The tip of the arm bears a small ligula (Fig. 1c). It is spoon-shaped, pointed distally, and has thickened margins. The oral face is crossed by about 12-13 low fleshy folds. The calamus is projecting, low, and blunt.

 

The gills are short, stout, and contain 6 lamellae on the outer demi‑branch.

 

None of the specimens appear to be sexually mature. The holotype had a well developed hectocotylus and penial apparatus but there were no spermatophores in Needham's sac nor were any found in the other males.

 

None of the females contained developed eggs.

 

The digestive tract was dissected from one of the large females (Fig. 1d). The buccal mass is large and contains large anterior salivary glands. The paired posterior salivary glands are very small and poorly developed. The esophagus leads from the buccal mass posteriorly to the crop which it enters dorsally. The latter has no diverticulum. Posteriorly the esopha­gus and crop lead into a stout portion which connects with a moderately large two-parted stomach, one part thick-walled and muscular, the other thin-walled. The spiral caecum is small, stout, smooth externally, and united with the small heart-shaped liver by paired hepatopancreatic ducts. The intestine is stout, thin-walled, and leads anteriorly to the anus which does not appear to have anal flaps. The crop was opened in one specimen. It contained an amorphous mass of animal tissue in which numerous polychaete bristles were embedded.

 

The beaks show no unusual features (Figs. le, f).

 

Radulas were removed from two specimens. While there is no ques­tion that all of the specimens are conspecific and show a remarkably close conformity in other characters, the radular teeth vary greatly. The radula from specimen No. 2 (Fig. 1g) has only 5 teeth in each trans­verse row, none of them showing any great dissimilarity. The rachidians are undifferentiated but somewhat larger than the second laterals and without cusps. The admedians or first laterals are missing. The second laterals are only slightly curved with small bases; the third laterals are largest, tallest, and broadest, with conspicuous bases. There is no trace of marginal plates.

 

The radula of specimen No. 3 (Fig. lh) has rather large, broad rachid­ians with broad bases, perhaps somewhat distorted in the figure by a sidewise orientation in the mount. The admedians are a little shorter than the second laterals, narrow and sharp. The second laterals are larger and more curved. The third laterals are very broad, almost flat­tened at their tips and show a slightly irregular outline. All of these teeth stand erect, are thin and transparent, and in No. 3 have very ir­regular almost root-like bases.

 

All of the specimens were fixed in 10 percent buffered formalin after brief emersion in fresh water to kill them. They were thus fixed without undue distortion of the arms and were later transferred to 70 percent alcohol. They are in remarkably fine condition for examination.

 

The general consistency is muscular with a thick overlying layer of almost gelatinous material, particularly posteriorly on the mantle and slightly less so dorsally, around the head and eyes, and surrounding the brachial crown. The surface is covered by a thin, very tough skin which is covered dorsally on the mantle, head and arms by numerous, evenly spaced, close-set warts (Fig. 2). These consist of a raised mound bearing from one to over a dozen small, cone-shaped papillae. They are very regularly distributed. There are none on arms IV; arms II and III are liberally covered dorsally but there are none ventrally. There is a dis­tinct line of fine warts on the periphery of the mantle arranged like a keel running from the corners of the mantle aperture around the mantle posteriorly. Below the keel there are no warts and the surface is smooth. There are no warts beneath the head except for a few bordering the lower eyelid and immediately adjacent to it. There is a distinct circlet of warts on the eyelid (Fig. 1i). These are somewhat larger than the other warts and two or three of them over each eye are greatly enlarged and, although not erected, probably represent ocular cirri.

 

The color of specimens in alcohol is a pale yellowish brown dorsally, suffused with purplish hues at the base of the brachial crown and on and between the arm bases. On this ground color the mantle, head, funnel, and the base of the arms are reddish brown suffused with purple. The spermatophoral groove on the third right arm is yellowish.

 

 

TABLE 1. Measurements (in mm) of 3 male specimens of Graneledone antarctica, new species, from ELTANIN Sta. 2110.

 

Holotype

 

 

                                                                                                                                               
 

No.

 
 

1

 
 

2

 
 

3

 
 

Mantle length

 
 

41

 
 

39

 
 

38

 
 

Mantle width

 
 

44

 
 

37

 
 

40

 
 

Head width

 
 

40

 
 

34

 
 

38

 
 

Arm length

 
 

I

 
 

164

 
 

165

 
 

138

 
 

138

 
 

138

 
 

136

 
 

 
 

II

 
 

164

 
 

164

 
 

123

 
 

130

 
 

127

 
 

136

 
 

 
 

III

 
 

150

 
 

145

 
 

112

 
 

105

 
 

119

 
 

117

 
 

 
 

IV

 
 

135

 
 

135

 
 

103

 
 

98

 
 

113

 
 

105

 
 

Total length

 
 

208

 
 

179

 
 

178

 
 

Arm width

 
 

8.0

 
 

7.0

 
 

7.0

 
 

Hect. arm length

 
 

145

 
 

105

 
 

117

 
 

Ligula length

 
 

4.5

 
 

4.0

 
 

3.8

 
 

Calamus length

 
 

2.0

 
 

2.0

 
 

1.5

 
 

Sucker diameter

 
 

3.3

 
 

2.3

 
 

2.2

 
 

Web depth

 
 

A

 
 

28

 
 

30

 
 

25

 
 

 
 

B

 
 

46

 
 

47

 
 

35

 
 

38

 
 

33

 
 

42

 
 

 
 

C

 
 

45

 
 

52

 
 

35

 
 

35

 
 

38

 
 

38

 
 

 
 

D

 
 

33

 
 

27

 
 

30

 
 

Gills

 
 

6

 
 

6

 
 

6

 
 

 

TABLE 2. Indices of bodily proportions of three males of Graneledone antarctica, new species, from ELTANIN Sta. 2110.

                                                                                                                                                    
 

No.

 
 

1

 
 

2

 
 

3

 
 

N

 
 

Range

 
 

S.D.

 
 

ML

 
 

41

 
 

39

 
 

38

 
 

3

 
 

38.0 – 39.3 – 41

 
 

1.52

 
 

MWI

 
 

107.3

 
 

94.9

 
 

105.3

 
 

 
 

94.9 – 102.5 – 107.3

 
 

6.65

 
 

HWI

 
 

97.6

 
 

87.2

 
 

100.0

 
 

 
 

87.2 – 94.9 – 100.0

 
 

6.80

 
 

MAI

 
 

24.9

 
 

28.3

 
 

27.5

 
 

 
 

24.9 – 26.9 – 28.3

 
 

1.77

 
 

ALI

 
 

79.3

 
 

77.0

 
 

77.5

 
 

 
 

77.0 – 77.9 – 79.3

 
 

1.20

 
 

AWI

 
 

19.5

 
 

18.0

 
 

18.4

 
 

 
 

18.0 – 18.6 – 19.5

 
 

0.77

 
 

WDI

 
 

31.5

 
 

27.5

 
 

30.4

 
 

 
 

27.5 – 29.8 – 31.5

 
 

2.06

 
 

SIn

 
 

8.0

 
 

5.9

 
 

5.8

 
 

 
 

5.8 – 6.6 – 8.0

 
 

1.24

 
 

HcAI

 
 

87.8

 
 

76.1

 
 

84.8

 
 

 
 

76.1 – 82.9 – 87.8

 
 

6.07

 
 

LLI

 
 

3.1

 
 

2.8

 
 

3.2

 
 

 
 

2.8 – 3.0 – 3.2

 
 

0.20

 
 

CLI

 
 

44.4

 
 

50.0

 
 

39.5

 
 

 
 

39.5 – 44.6 – 50.0

 
 

5.25

 
 

PLI

 
 

 
 

 
 

 
 

 
 

 
 

 
 

Arm formula

 
 

1.2.3.4

 
 

1.2.3.4

 
 

1.2.3.4

 
 

 
 

 
 

 
 

Web formula

 
 

CBDEA

 
 

BCDAE

 
 

CBDEA

 
 

 
 

 
 

 
 

Gills

 
 

6

 
 

6

 
 

6

 
 

 
 

 
 

 
 

 

TABLE 3. Measurements (in mm) of four females of Graneledone antarctica, new species, from ELTANIN Sta. 2110.

 

 

                                                                                                                                                        
 

No.

 
 

4

 
 

5

 
 

6

 
 

7

 
 

Mantle length

 
 

45.0

 
 

41

 
 

39

 
 

25

 
 

Mantle width

 
 

43

 
 

37

 
 

36

 
 

23

 
 

Head width

 
 

40

 
 

32

 
 

34

 
 

23

 
 

Arm length

 
 

I

 
 

131

 
 

134

 
 

99

 
 

102

 
 

116

 
 

115

 
 

60

 
 

62

 
 

 
 

II

 
 

134

 
 

134

 
 

98

 
 

99

 
 

108

 
 

114

 
 

62

 
 

61

 
 

 
 

III

 
 

122

 
 

118

 
 

97

 
 

93

 
 

96

 
 

102

 
 

58

 
 

60

 
 

 
 

IV

 
 

198+

 
 

114

 
 

86

 
 

57+

 
 

96

 
 

101

 
 

59

 
 

56

 
 

Total length

 
 

177

 
 

143

 
 

157

 
 

88

 
 

Arm width

 
 

8.0

 
 

5.5

 
 

6.0

 
 

6.0

 
 

Web depth

 
 

A

 
 

32

 
 

25

 
 

28

 
 

17

 
 

 
 

B

 
 

41

 
 

42

 
 

30

 
 

32

 
 

32

 
 

37

 
 

18

 
 

-

 
 

 
 

C

 
 

42

 
 

43

 
 

35

 
 

33

 
 

32

 
 

37

 
 

21

 
 

20

 
 

 
 

D

 
 

37

 
 

38

 
 

32

 
 

32

 
 

32

 
 

31

 
 

19

 
 

17

 
 

 
 

E

 
 

31

 
 

20

 
 

22

 
 

17

 
 

Gills

 
 

6

 
 

6

 
 

6

 
 

6

 
 

 

+ = tip broken

 

 

Holotype: U.S. National Museum of Natural History 729679.

 

Type-locality: Ross Sea, Antarctica, ELTANIN Sta. 2110, 74°05.6'S, 175°05.2'W in 2341 m.

 

Discussion: Two other species assigned to Graneledone must be con­sidered: G. challengeri (Berry, 1916) and ? G. setebos Robson, 1932.

 

G. antarctica superficially resembles G. challengeri in its bodily pro­portions. It differs from it in the structure of the funnel organ, hecto­cotylus, radula, and sculpture. The funnel organ in antarctica is formed of double oval pads slightly to moderately spilt anteriorly; in challengeri these organs are typically VV-shaped with narrow, pointed, anterior

 

 

TABLE 4. Indices of bodily proportions and counts of four females of Graneledone antarctica, new species from ELTANIN Sta. 2110.

                                                                            
 

No.

 
 

4

 
 

5

 
 

6

 
 

8

 
 

Range

 
 

S.D.

 
 

ML

 
 

45

 
 

41

 
 

39

 
 

25

 
 

25 – 37.5 – 45

 
 

8.69

 
 

MWI

 
 

95.6

 
 

90.2

 
 

92.3

 
 

92.0

 
 

90.2 – 92.5 – 95.6

 
 

2.25

 
 

HWI

 
 

88.9

 
 

78.1

 
 

87.1

 
 

92.0

 
 

78.1 – 80.5 – 92.0

 
 

5.97

 
 

MAI

 
 

33.6

 
 

40.2

 
 

33.6

 
 

40.3

 
 

33.6 – 36.9 – 40.3

 
 

3.83

 
 

ALI

 
 

75.7

 
 

71.3

 
 

73.9

 
 

70.5

 
 

70.5 – 72.8 – 75.7

 
 

2.39

 
 

AWI

 
 

17.8

 
 

13.4

 
 

15.3

 
 

24.0

 
 

13.4 – 17.6 – 24.0

 
 

4.61

 
 

WDI

 
 

32.1

 
 

34.3

 
 

31.9

 
 

33.9

 
 

31.9 – 33.1 – 34.3

 
 

1.22

 
 

 

limbs. In antarctica the ligula is a small and moderately well differentiated; in challengeri the ligula is well formed, deeply excavated, with sharply differentiated calamus. The radula of antarctica is highly variable but shows a general uniformity of teeth; in challengeri the radula is more typically octopodan. The sculpture of antarctica varies from challengeri in the more scattered, more widely separated tubercles, and the presence of 2 to 3 much larger tubercles over the eyes. The wide membrane on the ventral side of the arms in antarctica also seems distinctive.

 

There is no point of comparison with ? G. setebos for the reasons given in the general discussion.

 

The etymology of the name is self-evident.”

 

 

(Voss, 1976: 448-454)

Trusted

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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