Paucibranchia purcellana Molina-Acevedo 2018, n. comb.
Creators: name: Molina-Acevedo, Isabel C.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Eunicida
Eunicidae
Paucibranchia
Paucibranchia purcellana

description: Paucibranchia purcellana (Willey, 1904) n. comb.
Figures 60–62, Tables 1–2
Marphysa purcellana Willey, 1904:263 –264, Pl. 13, Fig. 17; Day 1960:335; Day 1963:408; Day 1967:397 –399, Fig. 17.6k–o; Katsiaras et al. 2014:208 –211, Figs. 6a–h, 7a–d, Table 2.
Material examined. Type material: Holotype BNHM 1911.2.1.13, off Woodstock beach, Table Bay, South Africa, between roots of sea bamboo, coll. W.T. Purcell.
Description. Holotype complete, dissected laterally, with 142 chaetigers, last 11 in regeneration, L10= 7.2 mm, W10= 4 mm, with TL= 92 mm. Anterior region of body with convex dorsum and flat ventrum, without groove; body depressed from chaetiger 9, widest at chaetiger 15, tapering after chaetiger 35.
Prostomium bilobed, 3.2 mm long, 1.6 mm wide, frontally rounded, without median sulcus (Fig. 60C), ventral sulcus deep (Fig. 60B). Prostomial appendages in a semicircle, equidistant. Palps reaching the middle of first peristomial ring; lateral antennae reaching second peristomial ring; median antennae reaching first chaetiger. Palpophores and ceratophores ring-shaped, short, slender; palpostyles and ceratostyles tapering, thick in the base, without articulation. Eyes rounded, dark, between palps and lateral antennae.
Peristomium wider than prostomium (2 mm long, 3.5 mm wide), first ring three times longer than second ring, separation between rings distinct on all sides (Fig. 60A–C). Inferior lip with a slight central depression, with a pair of shallow wrinkles (Fig. 60B).
Maxillary apparatus not examined, with MF= 1+1, 5+5, 5+0, 3+8, 1+1 according to Katsiaras et al. (2014).
Branchiae pectinate with up to 25 filaments, in chaetigers 8–27 (Figs. 60A, C; 61B). Number of branchial filaments per chaetiger in order anterior-posterior: 8, 10, 10, 12, 16, 20, 20, 20, 20, 20, 19, 10, 18, 11?, 15, 14, 13, 12, 10, 10. Branchial filaments slender, as long as dorsal cirri.
First parapodia smallest; most developed in chaetigers 3–30, following ones becoming gradually smaller. Notopodial cirri conical, increasing in size from chaetiger 3 (Ldc3: 0.36 mm; Ldc13: 0.43 mm), from chaetiger 39, gradually decreasing in width and increasing in length, in posterior region slender, 1.4 times longer than the prebranchial region ones (Ldc75: 0.50 mm) (Fig. 61A–E). Prechaetal lobes as a transverse fold in all chaetigers (Fig. 61A–E). Chaetal lobes in chaetigers 1–34, rounded, shorter than postchaetal lobes, with aciculae emerging dorsal to midline; from chaetiger 35, triangular, longer than other lobes, with aciculae emerging in midline (Fig. 61A–E). Postchaetal lobes well developed in chaetigers 1–68, bluntly conical; thicker and elongated in branchial chaetigers; decreasing in size in chaetigers 28–68, following ones inconspicuous (Fig. 61A–E). Ventral cirri digitiform in chaetigers 1–5; in chaetigers 6–36 with oval swollen base and digitiform tip; from chaetiger 37, conical, gradually reducing in size posteriorly (Fig. 61A–E).
Aciculae blunt, with reddish basal end, distally amber; in median-posterior chaetigers one of the two aciculae translucent, the second is reddish (Fig. 61A–E). First three chaetigers with 2 aciculae; in chaetigers 4–17 with 3 aciculae; in chaetigers 18–113 with 2 aciculae; from chaetiger 114, with only one acicula.
Limbate chaetae of two sizes in same chaetiger, larger in anterior region, reduced in number around chaetiger 33. Two types of pectinate chaetae; in anterior chaetigers isodonts narrow with long and slender teeth, with 3–4 pectinate, with up to 10–12 teeth, with transverse distal edge (Fig. 62A); in median-posterior chaetigers isodonts narrow with short and slender teeth, with 9–10 pectinate, with up to 14–16 teeth, with transverse distal edge (Fig. 62B). Compound falcigers present in all chaetigers; in anterior chaetigers with blade of three sizes (longer 112 µm, Fig. 62C; median 91 µm, Fig. 62D; smaller 72.8 µm, Fig. 62E), smaller more abundant; all with teeth triangular, of similar size, distal tooth directed upward, proximal tooth directed laterally; in media-posterior chaetigers with blades of similar size, shoter than blades of anterior chaetigers (56–50 µm, Fig. 62F), all with triangular teeth, distal shorter than proximal, directed upward, proximal tooth directed laterally. Subacicular hooks bidentate, reddish basal, distally amber; in posterior chaetigers translucent, starting in chaetiger 29; with rounded teeth, of similar size, distal tooth directed upward; proximal tooth directed laterally; with one or three hooks per chaetiger (Fig. 62G).
Pygidium with two pairs of anal cirri, without articulation; dorsal pair as long as last nine chaetigers; ventral pair short, as long as last chaetiger.
Distribution. Known only from type locality. Table Bay, Cape of Good Hope, South Africa
Remarks. Katsiaras et al. (2014) redescribed this species based on type and non-type material. They indicated that the falcigers have blades of two sizes in anterior chaetigers; however, I found, up to three blade sizes in such region.
Paucibranchia purcellana n. comb. resembles P. gathofi n. sp. and P. miroi n. sp. by having the subacicular hook bidentate, reddish basally and distally amber, and by the presence of only compound falcigers. However, they are different because in P. purcellana n. comb. there are falcigers with blades of three sizes in the anterior region and dorsal cirri are 1.4 times large in the postbranchial region; whereas in P. gathofi n. sp. and P. miroi n. sp. the falcigers have blades of two and one size in the same region, respectively, and the dorsal cirri are slightly shorter in postbranchial region in P. miroi n. sp. or of similar size comparing the pre- and postbranchial regions in P. gathofi n. sp.. Moreover, P. purcellana n. comb. has prostomium bilobed with a pair of eyes; whereas P. gathofi n. sp. has prostomium entire and P. miroi n. sp. lacks eyes. The comparison with others Paucibranchia n. gen. species having only compound falcigers present is provided in Table 2.
description: Published as part of Molina-Acevedo, Isabel C., 2018, Morphological revision of the Subgroup 1 Fauchald, 1970 of Marphysa de Quatrefages, 1865 (Eunicidae: Polychaeta), pp. 1-125 in Zootaxa 4480 (1) on pages 85-88, DOI: 10.11646/zootaxa.4480.1.1, http://zenodo.org/record/1453031