Paucibranchia totospinata ( Lu & Fauchald, 1998 ) Molina-Acevedo, 2018

Molina-Acevedo, Isabel C., 2018, Morphological revision of the Subgroup 1 Fauchald, 1970 of Marphysa de Quatrefages, 1865 (Eunicidae: Polychaeta), Zootaxa 4480 (1), pp. 1-125 : 106-111

publication ID	https://doi.org/ 10.11646/zootaxa.4480.1.1
publication LSID	lsid:zoobank.org:pub:0D3D99EC-107A-4D6B-B19E-52147C6C141E
DOI	https://doi.org/10.5281/zenodo.5953900
persistent identifier	https://treatment.plazi.org/id/CE78C444-FFA1-2114-FF5B-A5C2FEDCFB5F
treatment provided by	Plazi
scientific name	Paucibranchia totospinata ( Lu & Fauchald, 1998 )
status	comb. nov.

Treatment

Paucibranchia totospinata ( Lu & Fauchald, 1998) View in CoL n. Comb.

Figures 76–79 View FIGURE 76 View FIGURE 77 View FIGURE 78 View FIGURE 79 , Tables 1, 3

Marphysa totospinata Lu & Fauchald, 1998:839 View in CoL –841, Figs. 2–4 View FIGURE 2 View FIGURE 3 View FIGURE 4 , 6 View FIGURE 6 , 9a–h View FIGURE 9 .

Material examined. Type material: Holotype NMWZ 1988.069 View Materials .84, SE of Bleanmore Island , between Clew Bay & Blacksod Bay, Ireland, 16 Mar 1988 . Paratype NMWZ 1988.069.86 (3), NMWZ 1988.069 View Materials .85 (2), Same data as holotype. Additional material: ECOSUR-P 2172 (1), Gann Flat, Dale, Wales, 1 Aug 1988, coll. P. Garwood.

Description. Holotype complete, gravid female, with 327 chaetigers, broken into two parts (anterior fragment with 276 chaetigers), L10= 8.2 mm, W10= 2.5 mm, the fragment with TL= 160 mm. Anterior region of body with convex dorsum and flat ventrum, without groove; body depressed from chaetiger 7, widest at chaetiger 8, tapering after chaetiger 79.

Prostomium entire, 1.2 mm long, 0.9 mm wide, frontally rounded, without median sulcus ( Fig. 76A–C View FIGURE 76 ), ventral sulcus deep ( Fig. 76B View FIGURE 76 ). Prostomial appendages in a semicircle, median antenna isolated by a gap. Palps reaching second peristomial ring; lateral antennae reaching the middle of the second peristomial ring; median antenna reaching first chaetiger. Palpophores and ceratophores ring-shaped, short, slender; palpostyles and ceratostyles tapering, slender, without articulation, with some irregular wrinkles. Eyes light brown, reniform, between palp and lateral antenna.

Peristomium wider than prostomium (1.3 mm long, 1.9 mm wide), first ring two times longer than second ring, separation between rings distinct on all sides ( Fig. 76A–C View FIGURE 76 ). Inferior lip with a slight central depression ( Fig. 76B View FIGURE 76 ).

Maxillary apparatus examined in biggest paratype, with MF= 1+1, 6+7, 7+0, 5+8, 1+1 ( Fig. 77A–C View FIGURE 77 ). Maxillary carriers 2 times shorter than length of MI. MI forceps-like; closing system 6 times shorter than length of MI; ligament between MI and MII slightly sclerotized ( Fig. 77A–C View FIGURE 77 ). MII wide; teeth recurved, sharped; cavity opening oval, 3 times shorter than length of MII; ligament between MII and MIII, and right MIV, slightly sclerotized ( Fig. 77A–C View FIGURE 77 ). MIII short; with triangular teeth; with attachment lamella slightly sclerotized ( Fig. 77A– C View FIGURE 77 ). Left MIV with a small basal tooth; attachment lamella semicircular, wide, situated 1/3 along length of posterior edge of maxilla. Right MIV with similar size teeth; attachment lamella wide, better developed in the middle, situated 1/2 along length of posterior edge of maxilla ( Fig. 77A–C View FIGURE 77 ). MV rectangular, longer than wide, with a short rounded tooth ( Fig. 77A–C View FIGURE 77 ). Mandibles dark; cutting plates whitish, with 11 growth rings ( Fig.77D View FIGURE 77 ).

Branchiae pectinate with up to 19 filaments, in chaetigers 15 to 40L–41R ( Figs. 76C View FIGURE 76 ; 78C View FIGURE 78 ). Number of branchial filaments per chaetiger in order anterior-posterior: 12, 13, 12, 13, 14, 14, 15, 16, 16, 19, 19, 19, 18, 18, 17, 17, 17, 14, 16, 14, 14, 14, 11?, 13, 13, 10, 5. Branchial filament, slender and longer than dorsal cirri.

First two parapodia smallest; most developed in chaetigers 3–28, following ones becoming gradually smaller. Notopodial cirri conical, increasing in size from chaetiger 3 (Ldc3: 0.50 mm; Ldc28: 0.75 mm), from chaetiger 60, gradually decreasing in size, in posterior region the similar size than pre-branchial region (Ldc316: 0.55 mm); Hayashi & Yamane’s organ present ( Fig. 78A–F View FIGURE 78 ). Prechaetal lobes as a transverse fold in all chaetigers ( Fig. 78A– F View FIGURE 78 ). Chaetal lobes in chaetigers 1–46, rounded, shorter than postchaetal lobes, with aciculae emerging dorsal to midline; from chaetiger 47, triangular, longer than other lobes, with acicula emerging in midline ( Fig. 78A–F View FIGURE 78 ). Postchaetal lobes well developed in chaetigers 1–102; digitiform in pre-branchial chaetigers; conical, thinner, elongated in branchial chaetigers; decreasing in size in chaetigers 31–102, following ones inconspicuous ( Fig. 78A–F View FIGURE 78 ). Ventral cirri digitiform in chaetigers 1–6; in chaetigers 7–74 with oval swollen base and digitiform tip; from chaetiger 58, digitiform, gradually reducing in size posteriorly ( Fig. 78A–F View FIGURE 78 ).

Aciculae blunt, with reddish basal end, distally amber ( Fig. 78A–F View FIGURE 78 ). First 15 chaetigers with 3 or 4 aciculae; in chaetigers 16–37 with 2 aciculae; from chaetiger 39, with only one acicula.

Limbate chaetae of two sizes in same chaetiger, larger in anterior region, reduced in number around chaetiger 29. Two types of pectinate chaetae; in anterior chaetigers isodonts narrow with long and slender teeth, with 3–4 pectinate, with up to 7–8 teeth, with oblique distal edge ( Fig. 79A View FIGURE 79 ); in median-posterior chaetigers isodonts narrow with short and slender teeth, with 4–5 pectinate, with up to 7–8 teeth, with oblique distal edge ( Fig. 79B View FIGURE 79 ). Compound spinigers present in all chaetigers, with blades of two sizes, longer blade more abundant than median blade ( Fig. 79C–D View FIGURE 79 ). Compound falcigers present in all chaetigers, more abundant than spinigers; in anterior region with blades of two sizes (longer 87,5 µm, Fig. 79E View FIGURE 79 ; smaller 76 µm, Fig. 79F View FIGURE 79 ); all with triangular teeth, of similar size, distal tooth directed upward, proximal tooth directed laterally; in media-posterior chaetigers with blades of similar size, slightly shorter than blades of anterior chaetigers (63 µm, Fig. 79G View FIGURE 79 ), all with triangular teeth, distal shorter than proximal, directed upward, proximal tooth directed laterally. Subacicular hooks bidentate, with reddish basal end, distally amber, starting in chaetiger 41R–42L, with one hook per chaetiger, rounded teeth, distal tooth smaller than proximal tooth, directed upward; proximal tooth directed laterally ( Fig. 79H View FIGURE 79 ).

Pygidium with two pairs of anal cirri, without articulation; dorsal pair as long as last five chaetigers; ventral pair short, as long as three chaetiger ( Fig. 76D View FIGURE 76 ).

Variation. Material examined varied in the following features: L10= 1.7–8.2 mm, W10= 1.2–2.7 mm. Three of the six specimens were gravid females. Palps reaching second peristomial ring or first chaetiger. Lateral antennae reaching first chaetiger or middle of the first chaetiger. Median antenna reaching first or second chaetiger. The maxillary formula varies as follows: MII 6–7+7–8, MIII 7, MIV 5–7+7–8. The proportion of maxillary apparatus varies as follows: maxillary carriers shorter with respect to the MI varies 2–2.2 times; closing system shorter with respect to the MI varies 6–7 times; cavity opening shorter with respect to MII varies 2.8–3.6 times. Branchiae start in chaetigers 12–16 to 26–45. Maximum number of branchial filaments varied from 12 to 22. Well developed postchaetal lobe in first 59–102 chaetigers. Ventral cirri with swollen base from chaetigers 6–8 to chaetigers 51–65. Start of subacicular hooks in chaetigers 30–43.

Distribution. Ireland and Wales.

Remarks. This species is unique within Paucibranchia n. gen. by having compound falcigers and spinigers present on all chaetigers. Likewise, P. totospinata n. comb. is close to P. andresi n. sp. by having the subacicular hooks bidentate, reddish basally and distally amber, and compound falcigers and spinigers present; however, as was pointed out in the Remarks section of P. andresi n. sp., the species differ in the distribution of compound chaetae, the number of branchial filaments, and the sizes of blades of compound spinigers and falcigers. The comparison with the other Paucibranchia n. gen. species having compound falcigers and spinigers present is provided in Table 3.