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Species composition and distribution of pycnogonids in the Port of KaohsiungSun, Sung-Yao 21 August 2009 (has links)
The goal of the present research is to collect basic data for a study on the species composition and spatiotemporal distribution of pycnogonida (sea spider) in the Port of Kaohsiung. We used collecting net to collect samples from 8 stations within the Port of Kaohsiung during a 15-month period from March 2007 to May 2008. all pycnogonids collected were identified, if possible to species level, counted, and measured.
There were eight taxa of pycnogonids in our collection belonging to four family and seven genera, including: Achelia japonica with rounded trunk and pyramid proboscis, Ammothella sp. with palp and degrade chelifore, Tanystylum duospinum with rounded trunk which bears color stripes in live specimens, Callipallene amaxana with large and functional chelifore, Pigrogromitus timsanus with robust and short walking lags, Anoplodactylus spp.1and 2 without auxiliary claws, and Endeis sp. with elongate trunk and without cephalic appendages.
The average monthly catch of pycnogonid specimens from the Port of Kaoshiung in our collection was 111.4. Ammothella sp. was the most dominant taxon, contributing to 37.8% of the total collection while Anoplodactylus sp.2 was the laest abundant taxon, amounting to only 0.2¢H of the total number. Monthly catch of pycnogonids was not significantly different between months but significantly different between stations. Significant length difference between sex was noted in Ammothella sp.¡BC. amaxana¡BAnoplodactylus sp.1 and Endeis sp(P<0.05) and significant difference in monthly body length was found in T.duospinum and A. japonica (P<0.05).
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Nymphon (Pycnogonida) in the Eastern ArcticCranmer, Gary John January 1982 (has links)
Nymphon is the largest genus of Pycnogonida reaching its greatest diversity in the Polar regions. A revision of the genus within the Eastern Arctic has proved necessary due to the numerous nomenclatural complexities which have accumulated in the literature since its last major revision by Sars in 1891. This has been achieved using multivariate analyses involving the measurement of over 1500 specimens. Fifteen species are now recognized from the area and each has been redrawn and redescribed. It has not proved necessary to propose any new species. Two distinct sub-groups are found within the genus in this area, differing in leg morphology and reproductive strategy. The first group, exemplified by Nymphon stromi, has a leg morphology suited to walking or striding. A large number of lightly yolked eggs are typically produced and the larvae spend only a short period of their development on the male ovigers before they disperse. The other group, exemplified by Nymphon hirtipes, has a leg morphology more suited to clinging. Fewer eggs are produced but these are richer in yolk and the male overwinters with the larvae which are lost only when metamorphosis is nearly complete. These interspecific differences have been discussed and it is thought that they may enable direct competition to be avoided by the exploitation of different facets of the same environment. In addition, differences in the musculature have been discussed for species within Nymphon and for the Pycnogonida generally. The male ovigers of all species examined show various adaptations which increase the surface area compared with that of the female. These modifications have been discussed and are shown to afford a greater area for attachrnent of the maturing egg masses. A histological examination of the internal structure of the femoral cement glands of Nymphon hirtipes has revealed that the adult males have a broad band of glandular tissue lying under the epidermis whereas specimens in the final larval stage have little or none. The life-cycle of Nymphon hirtipes is postulated, showing the species to take between two and a half and three years to attain maturity. It breeds only once, during its final summer. This is compared with existing knowledge of the life cycles of shallow and tropical water species.
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