Two New Chaetognaths — Alvarino 
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TABLE 2 
Principal Differential Characteristics of the "Serratodentata Group” 
S. serratodentata 
Krohn 1853 
S. serratodentata 
atlantica Toki- 
oka 1940, 
Thomson 1947, 
Furnestin 1953, 
1957 
S. pseudoserrato- 
dentata Tokioka 
1939 
S. pacijica Tokioka 
S. serratodentata 
pacijica, Toki- 
oka 1940, 
Thomson 1947, 
Furnestin 1953, 
1957 
S. t as manic a 
Thomson 
S. serratodentata 
tasmanica 
Thomson 1947, 
Furnestin 1953, 
1957 
S. selkirki Fagetti 
1958 
S. bierii n. sp. 
Total 
length, 
mature, 
mm. 
10-13 
7-10 
12-14 
15-20 
14-17 
% tail 
23-26 
26-29 
23-26 
22-26 
20.5-23.3 
Body 
shape 
Same width from 
head to tail septum. 
Same. 
Same. 
Same. 
Neck region 
long, thin. Body 
widest at ovary 
region. 
Collarette 
Well apparent. 
Smaller than in 
S. serratodentata. 
As in S. pseudo- 
serratodentata. 
As in S. serrato- 
dentata. 
Very small, if 
present. 
Posterior 
fins 
Long, rounded. 
About same length 
on tail as on trunk. 
At level of tail, 
septum begins ray- 
less zone which ex- 
tends over anterior 
part of fin. 
Long, rounded, 
more on tail than 
trunk. Very close 
to posterior fins. 
Internal portion of 
fins on trunk is 
ray less. 
As in S. pseudoser- 
ratodentata. Very 
close to anterior 
fins. No rayless 
zone. 
Continuous with 
anterior fins by ex- 
tremely narrow 
connexion, not 
visible with low 
power 10X and in 
badly preserved 
specimens. More 
on tail than trunk. 
Rayless zone be- 
gins at level of first 
third of tail ex- 
tending over an- 
terior part of fin as 
in S. serratodentata. 
T riangular, 
rounded, more 
on trunk than 
tail. No rayless 
zone. 
Seminal 
vesicles 
Separated from 
tail fin, close to 
posterior fins. Two 
prominences at an- 
terior lateral cor- 
ner. Thickening of 
collarette tissue in 
front of anterior 
end. Markedly pro- 
tandric. 
Close to posterior 
end of posterior 
fins and at longer 
distance from tail 
fin. One promi- 
nence at lateral an- 
terior corner and 
small teeth at an- 
terior end. Pro- 
tandric. 
Oval with thicken- 
ing frothy tissue. 
5 — 10 chitinous 
teeth at anterior 
end. Protandric. 
Close to posterior 
fins, separated from 
tail fin. Numerous 
short protuber- 
ances at anterior 
end. Notable thick- 
ening in front and 
behind vesicle. 
Markedly protan- 
dric. 
Pear shape. One 
prominence and 
no soft protuber- 
ances as in S. 
tasmanica. 
Ovaries 
Long tubes extend- 
ing to anterior end 
of anterior fins. 
Ovulae small and 
in one row. 
Fine tubes extend- 
ing to anterior end 
of ventral ganglion. 
Ovulae large for 
size of specimens, 
arranged in one 
row. 
Very fine tubes, ex- 
tending up to neck. 
Ovulae in one row. 
Long tubes extend- 
ing to ventral gan- 
glion. Ovulae in 
two rows. 
Fine tubes ex- 
tending to pos- 
terior end of 
anterior fins. 
Ovulae in two 
rows. 
