Amphiglena gracilis, Capa & Rouse, 2007

Capa, Maria & Rouse, Greg W., 2007, 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, Journal of Natural History 41 (5 - 8), pp. 327-356 : 335-339

publication ID	https://doi.org/ 10.1080/00222930701194938
persistent identifier	https://treatment.plazi.org/id/9C3F6324-FFD3-FFFB-FE71-EBC329083259
treatment provided by	Felipe
scientific name	Amphiglena gracilis
status	sp. nov.

Treatment

Amphiglena gracilis View in CoL sp. nov.

( Figures 2 View Figure 2 , 3 View Figure 3 , 4A, B View Figure 4 )

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) .

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 View Figure 2 , 3A View Figure 3 ); tip of radioles without pinnules, longer than the pinnules ( Figure 2C View Figure 2 ). Dorsal lips about one-third of crown length, reaching about pinnule 3 of each radiole ( Figure 2E View Figure 2 ). Anterior peristomial ring short all around ( Figure 2A–E View Figure 2 ). 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 View Figure 2 ), not fused to the peristomial ring; appearing glandular ( Figure 3B View Figure 3 ). Peristomial eyes brownish and ellipsoid ( Figure 3B View Figure 3 ). 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 View Figure 2 ). 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 View Figure 2 ); breast well developed, handles medium to long ( Figure 4A View Figure 4 ). Companion chaetae geniculated, with straight shaft and very elongate mucro with several basal teeth of similar size ( Figure 2H View Figure 2 ). Three thin broadly hooded abdominal neurochaetae in each fascicle ( Figure 2G View Figure 2 ). 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 View Figure 4 ). Pygidial eyes a pair of orange-brown spots on lateral margins of pygidium ( Figure 3C View Figure 3 ). Statocysts not seen. Tube unknown. Eggs in the second and third abdominal chaetigers of holotype ( Figure 3D View Figure 3 ).

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.