Phylogenetic relationships within Amphiglena Claparède, 1864 (Polychaeta: Sabellidae), description of five new species from Australia, a new species from Japan, and comments on previously described species Author Capa, Maria Author Rouse, Greg W. text Journal of Natural History 2007 2007-03-26 41 5 - 8 327 356 http://dx.doi.org/10.1080/00222930701194938 journal article 10.1080/00222930701194938 1464-5262 5233796 Amphiglena gracilis sp. nov. ( Figures 2 , 3 , 4A, B ) Material studied Australia , New South Wales . Holotype : AM W30002 , North-west of Julian Rocks , Byron Bay , 28 ° 369480 S, 153 ° 379480 E, shell and gravel, 15 m depth , 3 March 1992 . Paratypes : AM W26004 , same sample ( 76 specimens ); AM W30402 , AM W30403 , AM W30404 , AM W30483 , AM W30484 , same sample ( SEM ). Additional material : AM W26005 , north-west of Julian Rocks , Byron Bay , 28 ° 369480 S, 153 ° 379480 E, gravel, 15 m depth , 3 March 1992 ( four specimens ) . AM W26006 , north-west of Julian Rocks , Byron Bay , 28 ° 369480 S, 153 ° 379480 E, shelly sand, 15 m depth , 4 March 1992 ( six specimens ) . Figure 2. Amphiglena gracilis sp. nov. SEM preparation, paratypes, AM W30402–AM W30404, AM W30483, AM W30484. (A) Whole specimen, lateral view; (B) anterior end, ventral view; (C) anterior end, dorsal view; (D) detail of base of crown and peristomium, ventral view; (E) base of crown and dorsal radiolar appendages; (F) notochaetae of fourth thoracic chaetiger; (G) mid-abdominal neurochaetae; (H) uncini, second thoracic chaetiger; (I) uncini and companion chaetae seventh thoracic chaetiger; (J) mid-abdominal uncini. Figure 3. Amphiglena gracilis sp. nov. Micrographs. (A) Whole specimen ventral view; (B) detail of anterior segments, ventral view; (C) pygidium and posterior segment, ventral view; (D) last thoracic and abdominal segments, ventral view. Description Holotype 2 mm long, crown one-quarter of its length, with eight thoracic and 15 abdominal chaetigers. Crown with four pairs of radioles with a few long pinnules arranged in two rows ( Figures 2A–C , 3A ); tip of radioles without pinnules, longer than the pinnules ( Figure 2C ). Dorsal lips about one-third of crown length, reaching about pinnule 3 of each radiole ( Figure 2E ). Anterior peristomial ring short all around ( Figure 2A–E ). Posterior peristomial ring collar absent. Ventral basal flanges present as two extensions from the first pinnule of the ventralmost radiole to junction of peristomium and crown ( Figure 2B, D ), not fused to the peristomial ring; appearing glandular ( Figure 3B ). Peristomial eyes brownish and ellipsoid ( Figure 3B ). Thorax longer than wide with quadrangular ventral shields similar in size. Superior notochaetae of first thoracic chaetiger narrowly hooded, inferior chaetae broadly hooded, two per fascicle ( Figure 2F ). Remaining thoracic chaetigers with one broadly hooded superior thoracic notochaeta and two paleate inferior thoracic notochaetae per fascicle. Second to eighth thoracic chaetiger with four to six thoracic uncini per fascicle, progressively increasing in size ventrodorsally on each torus, with about six rows of small and long teeth similar size above main fang, occupying half of its length ( Figure 2E–H ); breast well developed, handles medium to long ( Figure 4A ). Companion chaetae geniculated, with straight shaft and very elongate mucro with several basal teeth of similar size ( Figure 2H ). Three thin broadly hooded abdominal neurochaetae in each fascicle ( Figure 2G ). About four abdominal uncini per torus, with several rows of small teeth of similar size above the main fang; breast well developed, short handle, about half of the uncini width ( Figure 4B ). Pygidial eyes a pair of orange-brown spots on lateral margins of pygidium ( Figure 3C ). Statocysts not seen. Tube unknown. Eggs in the second and third abdominal chaetigers of holotype ( Figure 3D ). Figure 4. Line drawings of uncini. (A, B) A. gracilis sp. nov. : (A) thoracic uncini, seventh chaetiger; (B) midabdominal chaetiger. (C, D) A. bondi sp. nov. : (C) thoracic uncini, seventh chaetiger; (D) mid-abdominal chaetiger. (E, F) A. lenae sp. nov. : (E) thoracic uncini, seventh chaetiger; (F) mid-abdominal chaetiger. (G, H) A. magna sp. nov. : (G) thoracic uncini, seventh chaetiger; (H) mid-abdominal chaetiger. (I, J) A. maiteae sp. nov. : (I) seventh chaetiger; (J) mid-abdominal chaetiger. (K–N) A. nishii sp. nov. : (K, L) seventh chaetiger; (M, N) midabdominal chaetiger. Scale bar: 10 Mm. Variation The paratypes and rest of the additional material vary in the body length from 1.2 to 2.2 mm with the branchial crown from 0.5 to 0.8 mm . All have eight thoracic and between 12 and 16 abdominal chaetigers. The crown is one-third to half the length of the body, and in all the specimens observed there are four radioles with long pinnules; the tip of radioles is always longer than any of the pinnules. Some specimens have eggs from the first to the fourth abdominal chaetiger. Remarks Amphiglena gracilis sp. nov. is distinguished from other species in the genus by having a few very long pinnules from the proximal part of the radioles and long dorsal radiolar appendages (about one-third of the length of the crown). It is also characterized by the combination of anterior peristomial ring narrow all around, glandular flanges not fused to peristomium, and medium to long thoracic uncini handles. The abdominal neurochaetae are narrower than in other species of the genus. Amphiglena gracilis sp. nov. is similar to A. terebro in having ventral basal flanges not extending to the posterior peristomial ring, but the uncini of A. terebro show a narrow breast while in A. gracilis sp. nov. they are well developed. Etymology This species name refers to the Latin term for slender.