Amphiglena joyceae Tilic & Feerst & Rouse 2019, n. sp.
Creators: name: Tilic, Ekin
name: Feerst, Kathryn
name: Rouse, Greg W.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Sabellida
Sabellidae
Amphiglena
Amphiglena joyceae

description: Amphiglena joyceae n. sp.
(Figures 2–6)
urn:lsid:zoobank.org:act: 9A76ED88-2F2D-4C1A-9291-3BB9C768401B
Type locality Edithburgh, South Australia (35°05’03.8”S 137°44’55.3”E) Material examined. Holotype: SIO-BIC A9479 (GenBank COI sequence MK 813353), collected in the shallow intertidal, from the algal turf next to a jetty at Edithburgh, South Australia (35°05’03.8”S 137°44’55.3”E), May 21, 2006, G. Rouse. Fixed in formalin, preserved in ethanol. Paratypes: All collected in the same locality and date as the holotype; six fixed in formalin and preserved in ethanol. SIO-BIC A9480–A9484; two fixed in OsO4 and preserved in ethanol; two on SEM stub SIO-BIC A9486. Serial plastic sections of 1 paratype SIO-BIC A10038. One specimen destroyed for DNA sequencing.
Description. Holotype complete, with eight thoracic and 31 abdominal chaetigers (Fig. 2A). Total body length 2.8 mm (branchial crown 0.75 mm); maximum body width 0.6 mm (Fig. 2A). Crown holds five pairs of radioles with nine pairs of pinnules in two alternating rows. Pinnules similar in length along radiole. Radiolar skeleton with two rows of cells. Dorsal lips with short dorsal radiolar appendages. Posterior peristomial ring even in height all around (Fig. 3A, C). Anterior peristomial ring short and not visible laterally (Fig. 3C). No posterior peristomial ring collar. Ventral basal flanges present, short and not connected to crown (Fig. 3C). Red peristomial eyes present (Figs 2D, 5E). Thorax longer than wide. Second to eighth thoracic chaetigers with 4–7 uncini on each torus (Fig. 3A, B). Thoracic uncini with broad, well-developed breast double the space to the main fang (Fig. 4A). Approximately five rows of long teeth above main fang spanning half its length. Handles of thoracic uncini long (Fig. 4A). Companion chaetae present, with straight shaft and long mucro (Fig. 3C, D). Abdominal neurochaetae thin and broadly hooded (Fig. 4C). Uncini, with similar-sized small teeth above the main fang, well-developed broad breast, and medium length handles (Fig. 4B). Pygidial eyes present, red spots on lateral margins of pygidium (Fig. 2A). Faecal groove visible mid-dorsally along thorax (Fig. 3A). Pair of spermathecae present in base of dorsal lips, white pigmentation visible in live material (Fig. 2D). Eggs present in abdominal chaetigers, orange in live specimens (Fig. 2B, E). Intratubular brooding of juveniles (Fig. 2C). Tube transparent with sediment incorporated (Fig. 2B, D, E).
Etymology: Named for Kathryn Feerst’s grandmother Joyce Beck.
Remarks: Distinct morphologically and molecularly from all known species of Amphiglena including those described from Australia. The lack of connectivity of the ventral basal flanges and radioles is described in A. gracilis, A. magna and A. terebro. Amphiglena Joyceae n. sp. can be differentiated from A. gracilis by its larger body size and the lack of elongated distal pinnules. Furthermore, the companion chaetae in A. Joyceae n. sp. are much more broadly hooded and finely toothed than in A. gracilis. Amphiglena magna is much larger than A. Joyceae n. sp. and has 10 to 15 pairs of pinnules.
Histology: A paratype of Amphiglena Joyceae n. sp. was serially sectioned for histology (Fig. 5), allowing the investigation of the internal anatomy and the reconstruction of the 3D-structure of a spermatheca (Fig. 6). The spermathecae in A. Joyceae n. sp. are paired and lie at the base of the radiolar crown (Fig. 5E, F). They consist of a coiled narrow duct that opens inside a blind sac-like lumen. The total length of the duct was ± 40 µm and the empty lumen was ± 10 µm wide. The epithelial lining of the lumen was ± 15 µm thick and was densely ciliated (Fig. 6). No musculature was observed associated with the spermathecae and there were no sperm in the spermathecal lumen. The spermathecal structure is similar to that described in other Amphiglena spp. (Rouse & Gambi 1998b). Amphiglena terebro is the only species with a simple cavity like spermathecae, lacking the convoluted duct.
The prominent glandular ring of the posterior-most thoracic segments can be seen in the sections through the epidermis (Fig. 5D). The peristomial eyes are directly associated with the central nervous system and are located lateral to the cerebral ganglion (Fig. 5E). The single pair of nephridia, with a U-shaped duct, can be seen in the first thoracic segment (Fig. 5E).
The sectioned specimen only possessed early developing oocytes in abdominal segments 11–13 (Fig. 5D) no spermatids or spermatozoa were observed. Interestingly, no sperm was observed in the three cleared mature specimens either. While all known Amphiglena species are simultaneous hermaphrodites, this raises the question as to whether all collected specimens of A. Joyceae n. sp. were female.
description: Published as part of Tilic, Ekin, Feerst, Kathryn & Rouse, Greg W., 2019, Two new species of Amphiglena (Sabellidae, Annelida), with an assessment of hidden diversity in the Mediterranean, pp. 337-353 in Zootaxa 4648 (2) on pages 342-348, DOI: 10.11646/zootaxa.4648.2.8, http://zenodo.org/record/3354919