Myrianida phyllocera Augener, 1918

Nygren, Arne, 2004, Revision of Autolytinae (Syllidae: Polychaeta)., Zootaxa 680, pp. 1-314 : 148-149

Myrianida phyllocera Augener, 1918 (Fig. 73A–D)

Myrianida phyllocera Augener, 1918: 301 –304, pl. 4, fig. 87–89, textfig. 30A–D; Day 1953: 421 – 422; 1960: 319; 1967: 287, fig. 12.13L– O.

Not Myrianida phyllocera Rullier 1964 , pp. 166–167, fig. 12.

Material examined. South Africa: holotype ZMH V­ 8749, Lüderitz­Bucht., 0–10 m, 1911.

Diagnosis. Myrianida with extension of nuchal epaulettes to end of chaetiger 2; cirrostyles much flattened.

Description. Holotype a budding specimen 52 chaetigers in stock, with about 5 stolons. Length of stock 12 mm, including stolons c. 20 mm, width 1.4 mm. Preserved material yellowish without colour markings, live specimens with orange colour markings ( Day 1967). Ciliation as 2 trochs per segment.

Eyes separated; eye spots absent. Palps in dorsal view projecting 1/5 of prostomial length, fused (Fig. 73B). Nuchal epaulettes extending over chaetiger 2, diverging after the tentacular segment (Fig. 73A).

Antennae and tentacular cirri lost, first dorsal cirri reaching chaetiger 6–8, second dorsal cirri 1/3 as long as first dorsal cirri. From chaetiger 1–27 cirri with usual alternation in direction, followed by one DDDU­group, more posterior difficult to assess. Dorsal cirri from chaetiger 3, alternate in length; short cirri equals 1/2 of body width, long cirri equals 2/3 of body width. Cirrophores present on tentacular cirri, and all dorsal cirri. Cirrophores and cirrostyles unequal; cirrophores and cirrostyles on short cirri 1/2–2/ 3 in length of its counterpart in long cirri; cirrophores on short cirri shorter than parapodial lobes, cirrophores on long cirri longer than parapodial lobes; cirrophores shorter than cirrostyles. Antennae and tentacular cirri cylindrical ( Day 1967), cirri on chaetiger 1–4 with thick, slightly flattened cirrostyles, cirri on chaetiger 5–8 with gradually more flattened cirrostyles, more posterior with flattened cirrostyles.

Parapodial lobes of medium–large size, with anterodorsal part prolonged (Fig. 73C). Anterior chaetigers with 3 aciculae, 1–2 in median and posterior. Chaetal fascicle with 20 compounds in anterior chaetiger, 10–15 in posterior part of stock. Compound chaetae with small distal tooth (Fig. 73D). Single thin bayonet chaetae, beginning in stolonial chaetigers.

Pharynx with 1 long sinuation anterior and lateral to proventricle. Trepan in chaetiger 4–5, with c. 40 teeth, not possible to evaluate size of trepan teeth; trepan teeth arranged in 1 ring. Absence/presence of basal ring and infradental spines not possible to determine. Proventricle equal in length to 8–9 segments (specimen may be compressed) in chaetiger 11–19 with 55 rows of muscle cells.

Reproduction. Schizogamous reproduction by gemmiparity behind chaetiger 52.

Habitat. Shallow waters, 0– 10 m.

Distribution. South Africa.

Remarks. Myrianida phyllocera is closely allied to M. pinnigera ; these are the only Myrianida known with distinctly flattened dorsal cirrostyles. The holotype of M. phyllocera has rather short nuchal epaulettes reaching only chaetiger 2, but Day describes specimens with nuchal epaulettes reaching chaetiger 3–5, which comes closer to M. pinnigera where they reach chaetiger 6–12. The proventricle is larger in M. phyllocera , equal in length to 8–9 segments with c. 55 rows of muscle cells compared with 4 segments and c. 34 rows in M. pinnigera . The colour pattern described and figured by Day (1967) is identical with that found in M. pinnigera .