280
ELVEZIO GHIRARDELLI
S. inJlata present in the gulf, differing in the values of the length of the
tail and of the ovaries, are specimens of the same species a t different
stages of their sexual maturity (see p. 346).
I n order t o complete this information on the systematics of chaetognaths, one must necessarily mention the completely new classification
proposed by Tokioka (1965a). According to this author, the Phylum
Chaetognatha (Leuckart, 1894) is subdivided into two classes, of which
the first Archisagittoidea nov. has only a single extinct species:
Amiskwia sagittiformis Walcott. Although inclined t o the opinion of
Owre and Bayer (1962) who consider Arniskwia as being a nemertine
(see also p. 358) Tokioka cannot definitely reject the possibility that
Amiskwia might represent an ancient form of recent chaetognaths.
The second class Sagittoidea (Claus and Grobben, 1905) includes the
living forms and is in its turn divided in two orders :
(1) Phragmophora nov. Phragmatic structure made of the ventral
transverse musculature in the coelom. Usually various kinds of
glandular structures are seen on the body surface, in the neck or cephalic
region. This order is divided into two families: Spadellidae (Gen.
Spadella Langerhans) and Eukrohnidae (Gen. Eukrohnia RitterZahony, Heterokrohnia Ritter-Zahony and Bathyspadella Tokioka).
( 2 ) Aphragmgphora nov. The phragmatic structure is absent and
thus the whole coelom is entirely hollow. Glandular structures on the
body surface are scarcely developed. This order is divided into two
suborders :
(i) Ctenodontina nov. (Hooks are curved gently and teeth-rows are
comb-shaped, teeth are slender.) There are two families :
( a ) Sagittidae Claus and Grobben (Gen. Sagitta s.str. Quoy
and Gaimard, Zonosagitta nov., Xerratosagitta Tokioka and
Pathansali, Parasagitta nov., Aidanosagitta Tokioka and
Pathansali, Mesosagitta nov., Solidosagitta nov., Flaccisagitta
nov.).
( b ) Pterosagittidae nov. (Gen. Pterosagitta Costa).
(ii) Flabellodontina. (Hooks are curved rather abruptly and teeth
are stouter than in Ctenodontina and arranged fan-shape.) Pam.
Krohnittidae (Gen. Krohnitta).
I n all, 5 families, 15 genera and 65 taxa are included in Class
Of 65 taxa, three are defined as subspecies, one as a
Sagittoidea.
variety and three as forma, thus 58 are recognized as species.
ELVEZIO GHIRARDELLI
S. inJlata present in the gulf, differing in the values of the length of the
tail and of the ovaries, are specimens of the same species a t different
stages of their sexual maturity (see p. 346).
I n order t o complete this information on the systematics of chaetognaths, one must necessarily mention the completely new classification
proposed by Tokioka (1965a). According to this author, the Phylum
Chaetognatha (Leuckart, 1894) is subdivided into two classes, of which
the first Archisagittoidea nov. has only a single extinct species:
Amiskwia sagittiformis Walcott. Although inclined t o the opinion of
Owre and Bayer (1962) who consider Arniskwia as being a nemertine
(see also p. 358) Tokioka cannot definitely reject the possibility that
Amiskwia might represent an ancient form of recent chaetognaths.
The second class Sagittoidea (Claus and Grobben, 1905) includes the
living forms and is in its turn divided in two orders :
(1) Phragmophora nov. Phragmatic structure made of the ventral
transverse musculature in the coelom. Usually various kinds of
glandular structures are seen on the body surface, in the neck or cephalic
region. This order is divided into two families: Spadellidae (Gen.
Spadella Langerhans) and Eukrohnidae (Gen. Eukrohnia RitterZahony, Heterokrohnia Ritter-Zahony and Bathyspadella Tokioka).
( 2 ) Aphragmgphora nov. The phragmatic structure is absent and
thus the whole coelom is entirely hollow. Glandular structures on the
body surface are scarcely developed. This order is divided into two
suborders :
(i) Ctenodontina nov. (Hooks are curved gently and teeth-rows are
comb-shaped, teeth are slender.) There are two families :
( a ) Sagittidae Claus and Grobben (Gen. Sagitta s.str. Quoy
and Gaimard, Zonosagitta nov., Xerratosagitta Tokioka and
Pathansali, Parasagitta nov., Aidanosagitta Tokioka and
Pathansali, Mesosagitta nov., Solidosagitta nov., Flaccisagitta
nov.).
( b ) Pterosagittidae nov. (Gen. Pterosagitta Costa).
(ii) Flabellodontina. (Hooks are curved rather abruptly and teeth
are stouter than in Ctenodontina and arranged fan-shape.) Pam.
Krohnittidae (Gen. Krohnitta).
I n all, 5 families, 15 genera and 65 taxa are included in Class
Of 65 taxa, three are defined as subspecies, one as a
Sagittoidea.
variety and three as forma, thus 58 are recognized as species.