Paucibranchia conferta ( Moore, 1911 ) 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 : 36-40

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.5953867

persistent identifier

https://treatment.plazi.org/id/CE78C444-FFEB-215D-FF5B-A1D2FEDCFDAF

treatment provided by

Plazi

scientific name

Paucibranchia conferta ( Moore, 1911 )
status

comb. nov.

Paucibranchia conferta ( Moore, 1911) View in CoL n. comb.

Figures 23–25 View FIGURE 23 View FIGURE 24 View FIGURE 25 , Tables 1–2

Marphysa conferta Moore, 1911:252 View in CoL –254, Pl. XVI, Figs. 29–34 View FIGURE 29 View FIGURE 30 View FIGURE 31 View FIGURE 32 View FIGURE 33 View FIGURE 34 ; Hartman 1944:129; Hartman 1961:83.

Material examined. Type material: Holotype USNM 17328 View Materials , sta. 4431, off Brockway Point Santa Rosa Island, 15 Apr 1904, 75 m. Additional material : LACM-AHF POLY 10193 (1), Santa Monica Canyon, Southern California Bight , California, USA, North Pacific , Nov 1958, 54 56 m. LACM-AHF POLY POLY 10194 (2), R/V VELERO IV sta. 5712-58, 6 miles from Hyperion Sewage Treatment Plant Smokestack , bearing 270.5°T, El Segundo, Los Angeles County, Southern California Bight , California, USA, North Pacific , 33°55'50'' N 118°33'05'' W, 18 Apr 1958, in sand and gravel, grab, 88 m. GoogleMaps

Description. Holotype incomplete, gravid female, with 55 chaetigers, L10= 4.5 mm, W10= 0.8 mm, with TL= 21 mm. Anterior region with convex dorsum, and flat ventrum, without groove; body depressed from chaetiger 6, widest at chaetiger 11, tapering after chaetiger 46.

Prostomium entire, 0.6 mm long, 0.8 mm wide, lobe frontally rounded, without median sulcus ( Fig. 23A–B View FIGURE 23 ), ventral sulcus deep. Prostomial appendages in a semicircle, equidistant. Palps reaching the middle of the first peristomial ring; lateral antennae reaching second peristomial ring; median antenna reaching the middle of the first chaetiger. Palpophores and ceratophores ring-shaped, short, slender; palpostyles and ceratostyles tapering, thick, without articulation but with colored rings. Eyes rounded, brown, between palps and lateral antennae.

Peristomium wider than prostomium (0.8 mm long, 1.2 mm wide), first ring two times longer than second ring; separation between rings distinct on all sides ( Fig. 23A–B View FIGURE 23 ). Inferior lip with a central depression.

Maxillary apparatus with FM= 1+1, 7+6, 7+0, 5+7, 1+1 ( Fig. 23D View FIGURE 23 ). Maxillary carriers 2 times shorter than length of MI. MI forceps-like; closing system 8 times shorter than length of MI; ligament between MI and MII slightly sclerotized ( Fig. 23D View FIGURE 23 ). MII wide; teeth recurved; cavity opening oval, 3 times shorter than length of MII; ligament between MII and MIII, and right MIV, slightly sclerotized ( Fig. 23D View FIGURE 23 ). MIII short; with triangular teeth; with attachment lamella not sclerotized ( Fig. 23D View FIGURE 23 ). Left MIV with a small basal tooth; attachment lamella semicircular, sclerotized, wide, situated 2/3 along length of posterior edge of maxilla. Right MIV with small teeth; attachment lamella wide, better developed in the middle, situated 2/3 along length of posterior edge of maxilla ( Fig. 23D View FIGURE 23 ). MV rectangular, slightly longer than wide, with a short rounded tooth ( Fig. 23D View FIGURE 23 ). Mandibles not examined.

Branchiae pectinate with up to 7 filaments, in chaetigers 8–16 ( Figs. 23C View FIGURE 23 ; 24B View FIGURE 24 ). Number of branchial filaments per chaetiger in order anterior-posterior: 6, 6, 7, 7, 5?, 7, 7, 5, 4. Basal branchial filaments shorter than dorsal cirri.

First two parapodia smallest; most developed in chaetigers 3–24, following ones becoming gradually smaller. Notopodial cirri conical, increasing in size from chaetiger 4 (L5: 0.48 mm; Ldc25: 0.52 mm), from chaetiger 28, gradually decreasing in size ( Fig. 24A–E View FIGURE 24 ), in specimen LACM-AHF POLY 10193 (Ldc3 0.31 mm; Ldc120: 0.39 mm) posterior region 1.2 times longer than the pre-branchial region ones. Prechaetal lobes as a transverse fold in all chaetigers ( Fig. 24A–E View FIGURE 24 ). Chaetal lobes in chaetigers 1–18, rounded, shorter than postchaetal lobes, with aciculae emerging dorsal to midline; from chaetiger 19, triangular, longer than other lobes, with acicula emerging in midline ( Fig. 24A–E View FIGURE 24 ). Postchaetal lobes well developed in chaetigers 1–26, bluntly conical, thinner, elongated in branchial region; decreasing in size in chaetigers 14–26, following ones inconspicuous ( Fig. 24A–E View FIGURE 24 ). Ventral cirri digitiform in chaetigers 1–4; in chaetigers 5–25 with oval swollen base and digitiform tip, gradually reducing in size posteriorly; from chaetiger 26, conical ( Fig. 24A–E View FIGURE 24 ).

Aciculae blunt, with reddish basal end, distally translucent ( Fig. 24A–E View FIGURE 24 ). First 15 chaetigers with 2 aciculae; from chaetiger 16, with only one acicula.

Limbate chaetae of two sizes in same chaetiger, larger in anterior region, reduced in number around chaetiger 12. Two types of pectinate chaetae, in anterior chaetigers isodonts narrow with long and slender teeth, with 1–2 pectinate, with up to 8–9 teeth, with transverse distal edge ( Fig. 25C View FIGURE 25 ); in median-posterior chaetigers isodonts narrow with short and slender teeth, 2–3 pectinate, with 10–11 teeth, with transverse distal edge ( Fig. 25D View FIGURE 25 ). Compound falcigers present in all chaetigers; in anterior region with one-sized blade (49 µm, Fig. 25A View FIGURE 25 ); all with triangular teeth, of similar size, distal tooth directed upward, proximal tooth directed laterally; in media-posterior chaetigers with all blades of similar size, slightly shorter than blades of anterior chaetigers (43.3 µm, Fig. 25B View FIGURE 25 ), with triangular teeth, distal shorter than proximal, distal tooth directed upward, proximal tooth directed laterally. Subacicular hooks bidentate, translucent, starting in chaetiger 28, with one hook per chaetiger; with triangular teeth, distal tooth smaller than proximal, directed upward; proximal tooth directed laterally ( Fig. 25E View FIGURE 25 ).

Pygidium with two pairs of anal cirri; dorsal pair as long as last chaetigers; ventral pair short, as long as pygidium edge.

Variation. Material examined varied in the following features: L10= 2.3–4.5 mm, W10= 0.7–1 mm. Palps reaching first peristomial ring or middle of the first peristomial ring. Lateral antennae reaching second peristomial ring or first chaetiger. Median antenna reaching first chaetiger or middle of the first chaetiger. The maxillary formula varies as follows: MII 7+7–6, MIV 4–5+7. The proportion of maxillary apparatus varies as follows: maxillary carriers with respect to the MI varies 1.4–2 times; closing system with respect to the MI varies 7–8 times; cavity opening with respect to MII varies 2.5–3 times. Branchiae from chaetigers 7–8 to 13–16. Maximum number of branchial filaments varied from 6 to 8. Well developed postchaetal lobe in first 23–26 chaetigers. Start of subacicular hooks in chaetigers 15–28.

Distribution. Southern California, USA.

Remarks. This species has been recorded from Southern California to Natividad Island, Mexico ( Hartman 1944, 1961; Fauchald 1970), and Golfo Dulce, Costa Rica ( Dean 1996). However, the only specimen reviewed by Fauchald (1970) from Natividad Island (NI) differs from P. conferta n. comb. in several features. The specimen from NI (L10: 3.5 mm, W10: 0.9 mm) has translucent aciculae, compound falcigers with blades of two sizes in anterior chaetigers (longer 63 µm, smaller 46.2 µm), branchiae in chaetigers 9–22, and subacicular hook from chaetiger 26. Whereas, P. conferta n. comb. (L10: 3.4 mm, W10: 1 mm) has aciculae with a dark basal-middle region and distally translucent, compound falcigers with all blades of similar size (49 µm), branchiae in chaetigers 7–16, and subacicular hooks from chaetiger 18. It is possible that the specimen reviewed by Fauchald (1970) correspond to Paucibranchia sp. 2 or to another undescribed species. It is necessary to examine material available from NI to confirm this last hypothesis.

On the other hand, the specimens from Golfo Dulce, Costa Rica belong to a new species morphologically similar to P. conferta n. comb. (see Remarks section for Paucibranchia sp. 2).

Paucibranchia conferta n. comb. resembles P. adenensis n. comb., P. gemmata n. comb., and P. patriciae n. sp. by having a bidentate and translucent subacicular hooks, and falcigers present in all chaetigers. However, P. conferta n. comb. differs from P. adenensis n. comb. by the color of aciculae, which is reddish basally and translucent distally in the former and translucent in the latter; also, P. conferta n. comb. has compound falcigers with blades of similar size in anterior chaetigers, whereas in P. adenensis n. comb. falcigers have blades of two sizes. Concerning P. gemmata n. comb., this species lacks eyes, the dorsal cirri are two times longer in postbranchial chaetigers, and falcigers have blades of three sizes in anterior region; whereas P. conferta n. comb. has eyes, dorsal cirri are of similar size in pre- and postbranchial regions, and falcigers from anterior chaetigers have blades of the same size. The comparison with P. patriciae n. sp. is provided in the Remarks section on the latter species. The comparison with other Paucibranchia n. gen. species with only compound falcigers present is provided in Table 2.

Kingdom

Animalia

Phylum

Annelida

Class

Polychaeta

Order

Eunicida

Family

Eunicidae

Genus

Paucibranchia

Loc

Paucibranchia conferta ( Moore, 1911 )

Molina-Acevedo, Isabel C. 2018
2018
Loc

Marphysa conferta

Moore, 1911 :252
Hartman 1944 :129
Hartman 1961 :83
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