Full resolution (JPEG) - On this page / på denna sida - I. Description of the developed (imaginal) stages of Chordeuma obesum n. g., n. sp.
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some cases I have found only one simple claw on each side, probably the inner one
not having been developed.
Thie same appendages as in the female are present, and likewise the mandibles.
maxillulæ and eyes absent. The antennules (a1) are proportionally larger, somewhat less
clumsy than in the female, their terminal processes a little longer, generally curved
upwards and basally provided with a small spine; the lower and outer is a little
larger than the upper and inner one; a similar spine to that found in the female is
present on the middle of the ventral aspect of the antennule. The antennæ (a2) are
like those of the female; the maxillæ (mx) are both proportionally and absolutely
larger than in the female. The basal joint (Fig. 12, 1) carries on the inner side two
patches of small spines and a group of similar spines arranged more sparsely around
a central larger one; the second joint (2) has short, oblique, arched groups of spinelets
on the inner side, on the outer side scattered bristles, pointing towards the terminal
claw; the latter (3) is on the concave side provided with a large bristle and on the
convex side with a few smaller ones.
The thoracic feet (Fig. 1, p1—p4) are unsegmented, slender, almost threadlike,
and pointed: they may all be simple, but often a rudiment of the inner branch
is present on the members of second, third or fourth pair in the shape of a slender
papilla; it is always found in young specimens, largest shortly after their emerging
from the larval cuticle (Pl. II, Fig. 26, i); at that age it is present also on the first
pair of limbs. Hairs seem never to develop on the terminal part of the feet in
the male.
The smallest males found (Pl. II, Fig. 26) measure 0,36—0,48 mm, that is about
half the length of that of the smallest females observed. In the case of these small
males I am able to state with certainty that they unite recently have undergone
metamorphosis: all of them have been found together with the cast larval skin, in
many cases with the tip of the tail still enclosed inside the latter. As they, however,
are much larger than the ruptured cuticle — generally more than twice its size — they
must have grown considerably after emerging from it. In no case has any other
cuticle than that of the larva been found together with these males, and no more
than in the female have later stages shown any signs of further moultings. The
newly hatched males differ in several respects from their final shape: the body is
hardly curved, the head proportionally larger, the tail with two simple claws; the
appendages are proportionally larger, and all the thoracic limbs with distinctly developed
inner branch; furthermore in the antennules the lower and outer terminal process is
almost as long as the remaining part; as far as I have seen, it represents the greater
part of the long antennule in the larva, while only the first or the two first basal
joints of the latter are transformed into the clumsy antennule of the adult.
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