Paraproceraea, Nygren, Arne, 2004

Nygren, Arne, 2004, Revision of Autolytinae (Syllidae: Polychaeta)., Zootaxa 680, pp. 1-314 : 104-105

Paraproceraea gen. n.

Linnean name definition. Type species Autolytus(Autolytus) tamanus Imajima, 1966 .

PhyloCode definition. No name definition provided.

Apomorphies. Supported by 2 morphological characters ( Fig. 4 ): 1) nuchal epaulettes extend to chaetiger 3 (character 8), character state change is a reversal, and a parallelism; 2) number of teeth> 65 (character 40), character state change is a parallelism.

Etymology. Para is greek and means close to. Named for its similarity to Proceraea .

Paraproceraea tamana ( Imajima, 1966) comb. n. (Fig. 47A–F) Autolytus (Autolytus) tamanus Imajima, 1966: 46 –47, fig. 11E–K. NOT Autolytus tamanus San Martín 1994 272–273, fig. 2A–D.

Material examined. Japan: holotype NSMT­Pol H­ 1, Tamano, Torishima, 1964, 2 m.

Diagnosis. Procerini with nuchal epaulettes reaching middle of chaetiger 3, a thick type of bayonet chaetae, distally denticulated, and 90 small subequal teeth in trepan.

Description. Length 7.5 mm for 42 chaetigers, incomplete, width excluding parapodial lobes 0.5 mm at level of proventricle. Preserved material yellowish without colour markings, eyes brownish red. Live specimen orange with brown spot at the base of each dorsal cirri ( Imajima 1966).

Body, excluding parapodial lobes, cylindrical, venter flattened; body width fairly constant. Ciliation not possible to assess, anterior segments appear tri­annulated (Fig. 47A).

Prostomium rounded rectangular, wider than long. Four eyes, with lenses, in trapezoid arrangement, anterior pair larger. Eyes large, in dorsal view almost confluent (Fig. 47A); eye spots absent. Palps in dorsal view projecting 1/4 of prostomial length (Fig. 47A), fused. Extension of nuchal epaulettes to half of chaetiger 3 (Fig. 47A).

Antennae and first dorsal cirri lost. Dorsal tentacular cirri reaching chaetiger 7. Ventral tentacular cirri 1/3 as long as dorsal pair, second dorsal cirri as long as ventral tentacular cirri. From chaetiger 1–27 cirri with usual alternation in direction, followed by 3 DDUUgroups. Dorsal cirri from chaetiger 3 of equal length (Fig. 47B), 1/3 of body width excluding parapodial lobes. Cirrophores on tentacular segment and first dorsal cirri present; cirrophores otherwise absent (Fig. 47B). All appendages cylindrical, including lost anterior appendages ( Imajima 1966).

Parapodial lobes rounded, small (Fig. 47B). Aciculae numbering 2–3 in all present chaetigers. Chaetal fascicle with 10–15 compounds. Compound chaetae with small distal tooth in anterior 5–10 chaetigers (Fig. 47C), more posterior with larger distal tooth, still smaller than subdistal tooth (Fig. 47D); serration present. Single thick bayonet chaetae, distally denticulated (Fig. 47E), beginning from chaetiger 20.

Pharynx with sinuation anterior and lateral to anterior half of proventricle (Fig. 47F).

Trepan dissected, lost. Proventricle equal in length to 2 segments in chaetiger 5–6 with c. 25 rows of square shaped muscle cells. Posterior part lost.

Reproduction. Unknown.

Additional information. Imajima (1966) describes the trepan as having 90 subequal teeth arranged in one ring.

Habitat. Intertidal.

Distribution. North West Pacific. Southern Japan. Only known from type locality.

Remarks. Paraproceraea tamana is only known from one anterior end. The record of P. tamana from Cuba is not considered reliable, since the specimen has a thin bayonet chaetae, subdistally denticulated while the bayonet chaetae of P. tamana is thick, distally denticulated. The details of compound chaetae and proventricle do not match either. P. tamana is unique in having a combination of thick bayonet chaetae with 90 small subequal teeth. Unfortunately the trepan has been lost, and it is not possible to confirm Imajima's observations. Other Procerini with many teeth (>40) in their trepan includes Imajimaea zonata , I. japonensis ( Imajima & Hartman, 1964), and I. tsugara ( Imajima, 1966) ; all these taxa have thin bayonet chaetae, subdistally denticulated.

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.