Procerastea Langerhans, 1884

Nygren, Arne, 2004, Revision of Autolytinae (Syllidae: Polychaeta)., Zootaxa 680, pp. 1-314 : 92-94

Procerastea Langerhans, 1884

Procerastea Langerhans, 1884: 249 –250, fig. 5A–E.

Linnean name definition. Type species Procerastea nematodes Langerhans, 1884 by monotypy.

PhyloCode definition. No name definition provided.

Apomorphies. Clade supported by a single morphological character ( Fig. 4 ): simple chaetae in median and posterior chaetigers absent (character 29), character state change is a reversal, and a parallelism, later changed within clade.

General description.

Atokous form. Length 1.8–7.4 mm for 31–55 chaetigers (up to 25 mm (Allen 1921)); width, measured at level of proventricle and excluding parapodial lobes, 0.15–0.3 mm. Body shape, excluding parapodial lobes, cylindrical in transection, venter flattened; body width fairly constant with tapering end. Body in outline nearly thread­like, due to small parapodial lobes and absence of dorsal cirri from chaetiger 2. Ciliation absent, except for nuchal epaulettes (unknown for some taxa). Prostomium rounded rectangular, wider than long. Four eyes, with lenses, in trapezoid arrangement, anterior pair larger. Eyes confluent or separated, eye spots absent. Palps fused, small, in dorsal view not projecting in front of prostomium, or projecting 1/5 of prostomial length. Nuchal epaulettes maximally extending to end of tentacular segment.

Prostomium with 3 antennae; median antenna inserted medially on prostomium, lateral antennae on anterior margin. Tentacular cirri 2 pairs. Dorsal cirri only present on first chaetiger. Appendages club shaped or cylindrical. Except for bayonet chaetae, simple chaetae present in chaetiger 1–4, or in all chaetigers. Compound chaetae present from chaetiger 1, chaetiger 2, or absent. Both simple chaetae and compounds uni­ or bidentate with small distal tooth; blade serration absent. Single thick, distally dilated, bayonet chaetae, with distal denticulation.

Pharynx with very small sinuation, or with one to several small sinuations anterior to proventricle. Trepan teeth arranged in 1 ring, with 6–30 equal teeth. Basal ring absent; infradental spines absent. Proventricle with varying number of rows of square shaped muscle cells. Pygidium with 2 cirri (reported length compared to body width, excluding parapodial lobes, at level of proventricle if not otherwise stated), median papilla absent.

Epitokes.

Male. See description under Procerastea halleziana Malaquin, 1893 .

Female. See description under Procerastea halleziana .

Procerastea australiensis Hartmann­Schröder, 1987 (Fig. 40A–C)

Procerastea australiensis Hartmann­Schröder, 1987: 45 –46, figs 23–31.

Material examined. Australia: holotype ZMH P­ 18863, Point Lonsdale at Geelong, intertidal, algae and sand 24 Dec 1975; 1 paratype ZMH P­ 18864, Wilson's promontory, Lenoard Bay, cliff on northern squeaky beach, intertidal, algae and crusts, 27 Dec 1975.

Diagnosis. Procerastea with bidentate simple chaetae together with compounds in anterior 4 chaetigers; trepan with 6 indistinct teeth.

Description. Holotype complete, length 1.8 mm for 31 chaetigers (1.8 for 32 chaetigers in paratype), width 0.15 mm. Preserved material whitish, no colour markings. Ciliation not possible to assess.

Eyes separated (Fig. 40A); eye spots absent. Palps small, do not project in front of prostomium (Fig. 40A), fused. Nuchal epaulettes reaching over tentacular segment.

Median antenna reaching chaetiger 3–4. Lateral antennae 1/2 as long as median antenna. Dorsal tentacular cirri and first dorsal cirri 2/ 3 in length of lateral antennae. Ventral tentacular cirri 1/2 as long as dorsal pair. Dorsal cirri from chaetiger 2 absent. Small indistinct cirrophores on tentacular cirri and first dorsal cirri present. Appendages clavate (Fig. 40A).

Parapodial lobes small, rounded conical. Single acicula in all chaetigers. Chaetiger 1– 4 with 1 or 2 compounds and 2 simple chaetae (Fig. 40B), following chaetigers with 2–3 compounds (Fig. 40C). Compounds as well as simple chaetae with small distal tooth (Fig. 40B, C); serration absent. Single thick bayonet chaetae, distally dilated (Fig. 40B, C), beginning at chaetiger 1.

Pharynx with small sinuations anterior to proventricle (Fig. 40A). Trepan in tentacular segment (Fig. 40A) or chaetiger 1, with c. 6 indistinct teeth. Basal ring absent; infradental spines absent. Proventricle equal in length to 2 segments in chaetiger 4–6 with c. 20 indistinct rows of muscle cells. Anal cirri, as long as ventral tentacular cirri.

Reproduction. Unknown.

Habitat. Intertidal, algae, crusts.

Distribution. South West Pacific. South East Australia

Remarks. Procerastea australiensis is almost identical to P. nematodes Langerhans, 1884 . Number of chaetae is less in P. australiensis , at the most five in anterior chaetigers, compared to 9–13 in P. nematodes ; in addition the pharynx is also more convoluted in P. australiensis than in P. n e m a t o d e s.

Figures

FIGURE 4. Character transformations. Symbols as follow: black box, only one most parsimonious reconstruction (MPR) exists; white box, more than one MPR exist; X reversal; = parallelism; character later reversed within clade; character further changed within clade;? unknown character state for one or several taxa within clade.