Paraprocerastea

Nygren, Arne, 2004, Revision of Autolytinae (Syllidae: Polychaeta)., Zootaxa 680, pp. 1-314 : 98-100

Paraprocerastea San Martín & Alós, 1989

Paraprocerastea San Martín & Alós, 1989: 872 –877, fig. 1A–L.

Linnean name definition. Type species Paraprocerastea crocantinae San Martín & Alós, 1989 by original designation.

PhyloCode definition. No name definition provided.

Apomorphies. Clade supported by four morphological apomorphies ( Fig. 4 ): 1) cirrostyles egg shaped (character 15), other most parsimonious reconstructions (MPRs) possible, character state change is a parallelism; 2) simple dorsal chaetae of medium thickness (character 36); 3) simple dorsal chaetae even (character 37), character state change is a reversal; 4) pharynx sinuation minute (character 39), character state change is a parallelism.

Paraprocerastea crocantinae San Martín & Alós, 1989 (Fig. 44A–D)

Paraprocerastea crocantinae San Martín & Alós, 1989: 872 –877, fig. 1A–L. San Martín 2003: 458 –460, fig. 250A–L.

Material examined. Spain: holotype MNCN 16.01/620, Cabo de Creus, cala Taballera, Gerona, calcareous concretions of Mesophyllym lichenoides and Lithophyllum expansum , 12 m; 1 paratype on slide MNCN 16.01/622, off Los Genoveses inlet, Alméria, rhizomes of Posidonia oceanica , 3 m, June 1986.

Diagnosis. Procerini with only simple chaetae, and with dorsal cirri on all segments.

Description. Holotype complete, length 2.5 mm for 18 chaetigers (Fig. 44A) (length in paratype 3.4 mm for 33 chaetigers), width excluding parapodial lobes 0.3 mm at level of proventricle. Preserved material brownish, no colour markings. Ciliation not assessed. Body shape, excluding parapodial lobes, cylindrical in transection, venter flattened. Body width fairly constant with tapering end (Fig. 44A).

Prostomium rounded rectangular, wider than long. Four eyes, with lenses, in trapezoid arrangement. Eyes separated; eye spots present. Palps do not project in front of prostomium. Palps fused. Nuchal epaulettes not possible to assess, occipital flap not observed.

Median antenna reaching chaetiger 3–4. Lateral antennae 2/ 3 in length of median antenna. Dorsal tentacular cirri and first dorsal cirri, length 1/2 of lateral antennae. Ventral tentacular cirri 1/2 as long as dorsal pair. Alternation in direction of cirri not assessed. Cirri from chaetiger 2, of equal length, c. 1/8 of body width excluding parapodial lobes. Small cirrophores present on tentacular cirri, and first dorsal cirri; cirrophores otherwise absent. Lateral antennae, tentacular cirri and first dorsal cirri club shaped, median antenna cylindrical, dorsal cirri from chaetiger 2, ovoid to egg shaped.

Parapodial lobes rounded, small. All chaetigers with 1–2 aciculae. Chaetigers 1–4 with 4 simple chaetae, following chaetigers with 3 simple chaetae (Fig. 44B). Denticulation present along "fusion line" (Fig. 44B). Simple chaetae with small distal tooth; serration absent. Single medium­thick bayonet chaetae (Fig. 44B), distally denticulated, beginning at chaetiger 1.

Pharynx with minute sinuation anterior to proventricle. Trepan in tentacular segment, with 19–20 equal teeth (23 in paratype) (Fig. 44C, D). Basal ring absent; infradental spines absent. Proventricle equal in length to 1.5 segments in chaetiger 3–4 (4–5 in paratype) with 19–22 rows of square shaped muscle cells. Two anal cirri (Fig. 44A), as long as 1/3 of body width at level of proventricle.

Reproduction. Unknown.

Habitat. Calcareous concretions of Mesophyllym lichenoides and Lithophyllum expansum , 12 m.

Distribution. Mediterranean coast of Spain.

Remarks. Paraprocerastea crocantinae is most similar to taxa in Procerastea , in both general body outline and in the shape of the simple chaetae. Dorsal cirri is, however, absent in atokes of Procerastea from chaetiger 2, while present on all chaetigers in P. c ro ­ cantinae. The bayonet chaetae in Procerastea is of the thick, distally dilated, type, while a thinner, and even bayonet chaetae is present in P. crocantinae . The bayonet chaetae is, however, not as thin as in e.g. Autolytus , and is therefore called medium­thick. Paraprocerastea crocantinae was described as having an occipital flap covering most of prostomium; this could not be confirmed.

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.