Postembryonic development of antygomonas incomitata (Kinorhyncha: Cyclorhagida)

TY - JOUR

T1 - Postembryonic development of antygomonas incomitata (Kinorhyncha

T2 - Cyclorhagida)

AU - Sørensen, Martin V.

AU - Accogli, Gianluca

AU - Hansen, Jesper G.

PY - 2010/7/1

Y1 - 2010/7/1

N2 - Postembryonic development in the kinorhynch species Antygomonas incomitata was examined using scanning electron microscopy. The morphology of the six juvenile stages, J-1 to J-6, varies at numerous details, but they can also be distinguished by a few key characters. Juvenile stage 1 by its composition of only nine trunk segments; J-2 by the combination of possessing 10 trunk segments, but no cuspidate spines on segment 9; J-3 by the presence of cuspidate spines on segment 9, but only one pair of cuspidate spines on segment 8; J-4 by the combination of 10 trunk segments only, but having two pairs of cuspidate spines on segment 8; J-5 by possessing 11 trunk segments and same spine compositions as adults but is still maintaining postmarginal spiculae; J-6 specimens closely resemble adults and are most easily identified by their reduced trunk lengths. New segments are formed in a growth zone in the anterior part of the terminal segment. The complete number of segments is reached in J-5. Development of cuticular head and trunk structures are described through all postembryonic stages and following developmental patterns could be outlined: the mouth cone possesses outer oral styles from J-1, but in J-1 to J-3, the styles alternate in size. Scalids of the introvert are added after each molt, and scalids appear earliest in the anterior rings, whereas scalids in more posterior rings are added in older postembryonic stages. The early J-1 stage is poor in spines and sensory spots and both structures increase in number after each molt. The complete spine composition is reached in J-4, whereas new sensory spots appear after all molts, inclusive the final one from J- 6 to adult. Sensory spots in the paraventral positions often appear as Type 3 sensory spots but are through development transformed to Type 2. This transformation happens earliest on the anterior segments. J. Morphol. 271:863-882, 2010.

AB - Postembryonic development in the kinorhynch species Antygomonas incomitata was examined using scanning electron microscopy. The morphology of the six juvenile stages, J-1 to J-6, varies at numerous details, but they can also be distinguished by a few key characters. Juvenile stage 1 by its composition of only nine trunk segments; J-2 by the combination of possessing 10 trunk segments, but no cuspidate spines on segment 9; J-3 by the presence of cuspidate spines on segment 9, but only one pair of cuspidate spines on segment 8; J-4 by the combination of 10 trunk segments only, but having two pairs of cuspidate spines on segment 8; J-5 by possessing 11 trunk segments and same spine compositions as adults but is still maintaining postmarginal spiculae; J-6 specimens closely resemble adults and are most easily identified by their reduced trunk lengths. New segments are formed in a growth zone in the anterior part of the terminal segment. The complete number of segments is reached in J-5. Development of cuticular head and trunk structures are described through all postembryonic stages and following developmental patterns could be outlined: the mouth cone possesses outer oral styles from J-1, but in J-1 to J-3, the styles alternate in size. Scalids of the introvert are added after each molt, and scalids appear earliest in the anterior rings, whereas scalids in more posterior rings are added in older postembryonic stages. The early J-1 stage is poor in spines and sensory spots and both structures increase in number after each molt. The complete spine composition is reached in J-4, whereas new sensory spots appear after all molts, inclusive the final one from J- 6 to adult. Sensory spots in the paraventral positions often appear as Type 3 sensory spots but are through development transformed to Type 2. This transformation happens earliest on the anterior segments. J. Morphol. 271:863-882, 2010.

KW - Direct Development

KW - Evolution

KW - Juvenile Morphology

KW - Morphogenesis

UR - http://www.scopus.com/inward/record.url?scp=77954021687&partnerID=8YFLogxK

M3 - Journal article

C2 - 20544875

AN - SCOPUS:77954021687

SN - 0362-2525

VL - 271

SP - 863

EP - 882

JO - Journal of Morphology

JF - Journal of Morphology

IS - 7

ER -