Reference: Bio/. Bull. 208: 69-76. (February 2005) 2005 Marine Biological Laboratory Reproductive Biology of a New Hesionid Polychaete From the Great Barrier Reef FREDRIK PLEIJEL' * AND GREG W. ROUSE 2 Department of Marine Ecology, Tjdrno Marine Biological Laboratory; Goteborg University SE-452 96 Stromstad, Sweden, and Museum national d'Histoire naturelle, Departement Systematique et Evolution, CNRS UMR 7138. "Systematique, Adaptation, Evolution", 43, rue Cuvier, 75231 Paris Cedex 05, France: and 2 South Australian Museum. Nth Terrace, Adelaide, SA 5000, Australia, and School of Environmental & Earth Sciences. University of Adelaide. SA 5005, Australia Abstract. We describe Lizardia hirschi, a new hesionid genus and species, from shallow water on the Great Barrier Reef. It is characterized by small size (maximally around 2 mm long) and by males with paired penes on the last segment or the pygidium. The sperm are elongated, with a conical acrosome; extended, cylindrical nucleus; and three mitochondria. The females have three to four pairs of eggs in segments 10-13, up to 150 /urn in diameter. The female reproductive system consists of spermathecae. situated in the notopodia of segments 10-12, and oviducts opening ventrally on segment 11. Fertilization may be internal. The female (but not the male) reproductive system appears to be homologous to that in another small hesionid, capricornia. The phylogenetic position of L. hirschi within Hesionidae is currently uncertain due to the retention of many apparently larval features in the adults. Introduction Hesionids are generally not provided with external gen-ital organs (Pleijel, 1998, 2001). Recently, however, two new hesionids were described ( Westheide et ai, 1994, Plei-jel and Rouse, 2000). both of which have external genital organs. In Sinohesione genitaliphora Westheide, Purschke and Mangerich. 1994, the males have a pair of penes situ-ated on the ventral side of the neuropodia of segment 1 4, and the females have paired openings of the spermathecae Received 30 April 2004; accepted 14 October 2(104. * To whom correspondence should be addressed, at Tjarno Marine Biological Laboratory, SE-452 96 Stromstad, Sweden. E-mail: fredrik.
[email protected] in the same position but on segment 16. In capricornia Pleijel and Rouse, 2000 (see this description for spelling of taxon name with the initial letter in lower case), the males have a pair of large penes situated at the bases of the neuropodia of segment 9, and the females have spermathe-cae in the notopodia of segments 1 1 and 12. Based on the phylogenetic relationships (Pleijel and Rouse, 2000), the external reproductive organs in these two taxa were consid-ered nonhomologous. Here we introduce a third taxon with external genital organs, occurring as paired penes on the posterior end on the males, collected from several localities in shallow water on the Great Barrier Reef. Similar to capricornia. this new hesionid is very small, reaching only 2 mm in length, and has a number of characters in common with juvenile stages of other hesionids. Materials and Methods Specimens were extracted from scuba-collected sand and gravel samples by decantation through a 250-/u,m sieve and relaxed in a mixture of 7% (by weight) of MgCl 2 6H 2 O (in distilled water) and filtered seawater (see Rouse and Pleijel. 2001, for details). Relaxed specimens were studied alive, then processed for long-term storage and LM (light micros-copy), SEM (scanning electron microscopy), or histology and TEM (transmission electron microscopy). For long-term storage, specimens were fixed in 10% formaldehyde (i.e.. 25% formalin) in filtered seawater for one or a few days, rinsed in distilled water, and transferred to 70%-80% ethanol. Specimens for DNA extraction were fixed in 70% ethanol. Specimens for SEM were preserved for one hour in l%-2% osmium tetroxide in filtered seawater. rinsed and 69
Specimen codes extracted from OCR text.
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